ITTO Project PD 105/01 Rev.3 (F): Towards sustainable timber production in Ghana: Stage 1. Improving shoot borer resistance and developing silvicultural systems to maximize mahogany plantation success

PROJECT FINAL TECHNICAL REPORT

Authors Dr. Emmanuel Opuni-Frimpong Dr. Beatrice Darko Obiri Ms Sandra Owusu Mr. Lord Ameyaw Kwakye Mr. Emmanuel Ebanyenle Dr. Joseph R. Cobbinah Dr. Andrew Storer

Project Technical and Scientific Staff

Dr. Emmanuel Opuni-Frimpong Dr. Beatrice Darko Obiri Ms Sandra Owusu Mr. Lord Ameyaw Kwakye Mr. Emmanuel Ebanyenle Dr. Joseph R. Cobbinah Forestry Research Institute of Ghana, University P.O Box 63, Kumsi Ghnan

Prof. Andrew J. Storer Prof. David F. Karnosky School of Forest Resources and Environmental Science, Michigan Technological University, 14000 Townsend Drive, Houghton MI 49931, USA

PLACE: FORIG Kumasi, Ghana DATE: December 28, 2010

DURATION OF THE PROJECT: 48 Months

Table of Contents Pages

Summary 4 Major Research 1. Genetic x Environment Interaction of African Mahoganies for Growth and Response to Shoot Borer Hypsipyla robusta (Lepidoptera: Pyralidae) 5

Major Research 2. Relative susceptibility of four species of African mahogany to the shoot borer Hypsipyla robusta (Lepidoptera: Pyralidae) in the moist semideciduous forest of Ghana. 26

Major Research 3. Silvicultural systems for plantation mahogany in Africa: Influences of canopy-shade on tree growth and pest damage 40

Major Research 4. Silvicultural systems for plantation mahogany in Africa: Effect of mixed species stands on growth and Hypsipyla attack of African mahogany (Khaya anthotheca and K. ivorensis) 57

Major Research 5. In vitro propagation technology for African mahoganies, Khaya anthotheca Welw. and K. ivorensis A. Chev. 72

Major Research 6. Key roles of leaves, stockplant age, and auxin concentration in vegetative propagation of two African mahoganies: Khaya anthotheca and Khaya ivorensis 84

Major Research 7. Variation in wood properties (anatomy) in relation to Hypsipyla attack. 95

Major Research 8. Socio-economic studies for integrated Mahogany plantations with community farmers in Ghana 101

Summary

African mahoganies (Meliaceae: Swietenoidae) are regarded as the most valuable timbers in Ghana and are important exports in the international timber market. The bark is used medicinally to manage malaria, repel and kill mosquitoes. Mahognay is also used in dyeing and tanning leather. Continued supply and conservation of mahogany are threatened by overexploitation of natural mahogany forests which has exceeded natural regeneration for decades. Exacerbating the situation is the inability to establish mahogany plantations in their native range as a result of the Hypsipyla shoot borer that kills the main stem of the young trees, causing excessive forking and branching and contributing to mortality. Thus, it is critically important for the sustainability of native mahoganies that a program be established to reforest mahoganies via plantation culture by developing silvicultural methods to reduce the impact of Hypsipyla. In this research project, we identified borer-tolerant African mahogany from range-wide tests of various seed sources in different forest types, and we developed technologies to multiply tolerant mahogany planting stock. We examined mixed plantations and overhead-canopy shade effects on growth and Hypsipyla attacks in mahogany plantations. We also examined the wood anatomical properties of naturally grown (that escaped shoot-borer attack) and plantation grown K. ivorensis, which survived severe shoot-borer attack, aimed at predicting their wood quality. The project also seeked to develop and promote integrated mahogany plantations in collaboration with communities, assessing the economics and sociological implications of Mahogany and smallholder plantation development in Ghana. The results provide information that can be used in an integrated pest management of Hypsipyla in plantations and contribute to restoration and conservation of African mahogany in Western Africa.

Major Research 1.

Genetic x Environment Interaction of African Mahoganies for Growth and Response to Shoot Borer Hypsipyla robusta (Lepidoptera: Pyralidae)

E. Opuni-Frimpong1, D.F. Karnosky2, A.J. Storer2, and J.R. Cobbinah1 1 Forestry Research Institute of Ghana, University Box 63, Kumasi, Ghana 2School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Drive, Houghton MI 49931, USA

E-mail address: [email protected] and [email protected] (E. Opuni-Frimpong)

Abstract

African mahoganies, Khaya ivorensis and K. anthotheca (Meliaceae: Swietenoidae), are among the most valuable tropical timbers. They have been over exploited in their natural stand and attempts to establish plantations have mostly failed because of the mahogany shoot borer, Hypsipyla robusta that causes severe damage to young stands. The mahogany shoot borer kills the main stems of young trees resulting in excessive branching and reduced wood quality. We carried out this study to identify mahogany provenances/families tolerant to Hypsipyla attack in 3 different ecological regions in Ghana. Seedlings from 17 K. anthotheca parent trees representing 4 provenances in two ecological regions, and 11 K. ivorensis parent trees representing 3 provenances in two ecological regions were planted at three common sites representative of 3 main ecological zones where mahogany grows in Ghana. To monitor response to Hypsipyla attack, we measured tree height, diameter, height to first fork, number of branches, trees attacked and number of dead shoots. The data was subjected to analysis of variance using the GLM procedure in SAS and means were compared among families and provenances verses ecological regions by Tukey’s multiple range test α = 0.05. The differences in all the parameters measured were significant (P<0.05) among the different families and provenances as was the interaction with the different ecological types. Some families demonstrated a high level of tolerance despite persistence attack. Key Words: Provenance, Genotypes, Ecological-region, Hypsipyla, Shoot borers, Tolerance.

1.0 Introduction

African mahogany (Meliaceae) including Khaya, Entandrophragma, Guarea and Lovoa species, are considered among the most valuable tropical timbers worldwide. These species are found naturally throughout the moist and dry forest zones of West Africa (Hawthorne, 1995; Hall and Swain, 1981). Timbers from native mahogany contribute significantly to timber exports in the sub-region. On average the mahoganies contributed about 15-30% of timber exports in Ghana, Cote d’Ivoire and Nigeria up to the 1970’s (Atuahene, 2001). This has led to the severe reduction of the standing crop of these species in natural forests. The mahoganies in Ghana have been estimated to go commercially extinct by the end of this decade (Alder, 1989). The situation is no better in the neighboring West African countries. Continuous over-exploitation may lead to listing all African mahoganies on CITES appendix II, endangered list (Lemes et al., 2003). The inclusion of the mahoganies on this list would oblige timber companies to get a special permit before they can further harvest these species and forces the governments of exporting countries to warrant that the species are adequately stocked in the forests.

Since the last quarter of the last century, the population of mahoganies has been dwindling in its natural range of distribution due to a number of factors, particularly deforestation and selective exploitation of the best individual trees. These factors reduce mahogany populations and have negative effects on the genetic constitution of the remaining population (Snook, 2003; Patino, 1997; Atuahene 2001; Mayhew and Newton, 1998). Mahogany regeneration has been observed to be unsuccessful in the natural forest after selective harvesting under deep canopy shade and when there is regeneration survival is far too low compared to the rate of exploitation (Snook and Negreros-Castillo, 2004; Negreros-Castillo et al., 2003; Snook 2003; Grogan et al., 2003). Conservation and sustainable utilization of mahogany can only be realized when successful plantations are established. It is necessary to implement measures to guarantee African mahogany sustainable production including establishing Meliaceae in plantations. Unfortunately, most of the plantations that were established in the 1960s have been compromised by destructive attacks by the shoot borer Hypsipyla robusta (Atuahene 1972 2001; Roberts, 1966; Entwistle, 1967; Grijpma 1976; Ofosu-Asiedu et al., 1991). In West Africa, Hypsipyla has been recorded on Khaya spp, Entandrophragma spp, Carapa procera, C. grandiflora, Lovoa trichiniodes and Swietenia macrophylla (Roberts 1968; Wagner et al., 1991; Newton et al., 1993). The principal borer damage consists of destruction of the apical shoots. Repeated attacks on the leading shoots results in epicormic branching, stunted growth, multiple leaders and, in some severe cases, death. The excessive branching as a result of the death of the terminal shoots adversely affects wood quality (Wagner et al., 1991; Newton et al., 1995; Dupuy, 1995). The mahogany shoot borer is perhaps the most economically important insect pest in West African forests. The problem has attracted a great deal of attention from foresters, ecologists, entomologists, and plant chemists, but previous attempts at controlling Hypsipyla have largely been unsuccessful because of the cryptic nature of the pest (Wagner et al., 1991; Newton et al., 1993). Recently, however, the prospects for managing the mahogany shoot borer in West Africa and elsewhere have increased markedly with the identification of partial resistance within Swietenia macrophuylla and Cedrela odorata to Hypsipla grandella (Newton et al., 1993, 1994 1995; Watt et al., 2001). Recent studies on damage by Hypsipyla to native mahoganies in Ghana identified different levels of tolerance in native mahoganies (Opuni-Frimpong, 2000) suggesting selection of resistant mahogany genotypes may be possible. Attempts to control Hypsipyla by spraying insecticides have repeatedly failed as a result of high rainfall and the fact that the larvae are usually feeding within the pith of their host which is inaccessible to the sprays (Gripma, 1974; Allan et al., 1976; Wagner et al., 1991; Brunck and Mallet, 1993). Although attack by shoot borers may be significantly reduced by repeated (every six weeks) applications of DDT (Ramirez-Sanchez, 1976), this level of application of this toxic insecticide is clearly impractical on economic and environmental grounds (Wilkins et al., 1976). In addition, natural predators which control Hypsipyla are likely to be adversely affected by frequent use of non-specific insecticides. It has been suggested that controlled release (systemic) insecticides may provide economical and ecological advantages when compared with conventional spraying because of the lower volume of insecticide required and their greater degree of specificity (Allan et al., 1976; Wilkins et al., 1976). However, field trials have found them to be ineffective in controlling Hypsipyla (Ramnarine, 1992). Although there are several management alternatives to minimize shoot borers impacts, the best strategies will likely include reducing damage to a tolerable level by using a number of different methods in an integrated way (Grijpma, 1974; Morgan and Suratmo, 1976; Newton et al., 1993). Thus, Newton et al., (1993) and Floyd (2001) recommended an integrated pest management strategy based on the incorporation of pest resistant planting stock in silvicultural systems, which encourages natural biological control. In this paper, we examine the possibility of identifying shoot borer resistance/tolerance in African mahoganies through a provenance study of K. anthotheca and K. ivorensis, from the three main mahogany ecological zones in Ghana.

2.0 Applied methodology 2.1 Study Sites.

The high rain forest of Ghana is characterized into 4 major vegetation types or ecological zones (Hall and Swaine, 1981): Wet Evergreen, Moist Evergreen, Moist Semideciduous and Dry Semideciduos forest types. We established plantations for our study in 3 of the 4 major ecological regions (figure 1). These plantations were located at: 1) Afram Headwaters located at Latitude 7o07`N and Longitude 1o45`W in the dry semideciduous forest type with mean annual rainfall of 1250 to 1500mm, 2) Bobiri forest reserve located at latitude 6o40`N and longitude 1o19`W in the moist semideciduous forest type with mean annual rainfall is between 1200 and 1800mm and 3) Manso Amanfi located at 5o37`N and 2o15`W in the moist evergreen forest type with mean annual precipitation ranges between 1500 and 1800mm.

2.2 Seed sources and seedling production

Seeds of K. anthotheca and K. ivorensis were collected from plus trees (phenotypically superior trees, straight bole and dominant crown height) located in different forest ecological zones across the range of mahogany in Ghana. For the purposes of our discussion, seeds and seedlings from a single parent are referred to as families, and sites where these families were located are referred to as provenances. Khaya anthotheca seeds were collected from a total of 17 trees (families) at four different sites (provenances) representing two of the three ecological forest zones. Three provenances were represented in the dry semi-deciduous zone, with 7 families from Asempaneye and Abofour, 1 family from Akumasi-Dumasi in the dry forest and three families from Boabeng- Fiema. One provenance was represented in the moist semideciduous forest with 6 families from Akwasiho. Khaya ivorensis seeds were collected from a total of 11 trees at three different sites representing two of the three ecological forest zones. Two provenances were represented in the moist semi-deciduous zone, with 6 families from Bobiri forest reserve and 5 families from Amantia. A single family represented the moist evergreen zone from Agona-Wasa (Table 1). We did not get proportional numbers of families from each provenance because superior trees bearing seeds were not available. In some situations, all mature mahogany trees were already logged supporting the urgent need for this study.

Table1: Sources of seeds of two African mahogany species, provenances and families used to identify tolerant trees to Hypsipyla attack ______Species Provenances Families Forest Type ___ Khaya anthotheca Akwasiho G1-G6 Moist semideciduous Asempaneye/Abofour G7-G13 Dry semideciduous Akumasi Dumasi G14 Dry semideciduous Boabenfiema G15-G17 Dry semideciduous Khaya ivoriensis Bobiri G18-G23 Moist semideciduous Amantia G24-G27 Moist semideciduous Agona Wassa G28 Moist evergreen ______

GSW

DS

٭MSDNW

٭MSDSE

ME DS ٭ WE

Figure 1. Vegetation map of Ghana; WE – Wet Evergreen, ME – Moist Evergreen, MSDE – Moist semideciduous northwest, MSDSE – moistsemideciduous southeast, DS, .Study sites٭ .Dry semideciduous, GSW, Guinue Savanah Woodland

Seeds were geminated and grown in 10x20 cm plastic pots in the Forestry Research Institute of Ghana nursery at Mesewam near Kumsi. Healthy seedling were selected and transported to our planting sites after 3 to 5 months. The seedlings were planted at the three plantation sites at (1) the Bobiri forest reserve, (2) Afram-Headwaters and (3) Manso-Amanfi.

2.3 Experimental design and data collection

The seedlings were planted in three blocks using a randomized complete block design at each planting site. Each seed source was represented by 15 trees (5x3) in a block and was replicated in 3 blocks (Table 1). The seedlings were evaluated quarterly and complete assessment of all growth indexes and Hypsipyla damage indexes were taken annually. The growth parameters measured were tree height, diameter at breast height and height to first fork (crown height). Hypsipyla damage to the trees were assessed by counting total shoots sprouted in response to attacks, number of trees attacked, number of fresh attacks (attacks with fresh frass indicating presence of larva), and length of stem dieback.

2.4 Data analysis

The seed sources (families) represented the independent variables. Data were subjected to analysis of variance (ANOVA) using the GLM procedure in SAS (SAS Institute, 2004) and means were compared among seed sources (families and provenances) verses ecological zones by using Tukey’s multiple range test  = 0.05. The same analysis was used to compare the interaction of the different families and provenances with the different ecological zones; Bobiri, moist semideciduous forest type, Afram-headwaters, dry semideciduous forest type and Manso-Amanfi, moist evergreen forest type.

3.0 Presentation of the data

3.1 Variation in growth

The growth parameters we measured revealed differing tree height, diameter and height to first fork between the 2 Khaya species, provenances, families and ecological regions where the trees were planted (Table 2). At 36 months after planting in the field mean height of families range between 122.32 and 385 cm, in the moist semideciduous forest type at Bobiri (Figure 2a). K. anthotheca and K. ivorensis mean heights were 300.11 and 214.83 cm and ranged from 215.02 to 385.09 cm and 122.32 to 270.79 cm, respectively. The variation in height between families were not significant (P = 0.121) but high significant variation in height was recorded between K. anthotheca and K. ivorensis and provenances in Bobiri, (P <0.001). At the moist evergreen forest type in Manso Amanfi, the height varied from 89.66 to 206.86 at 36 months between families (Figure 2b). K. anthotheca and K. ivorensis had mean height of 172.39 and 113.28 cm and ranged from 134.68 to 206.86 cm and 89.66 to 128.23 cm respectively. On the other hand, the family variation in height at the dry forest area in Afram-Headwaters ranged from 61.29 to 179.92 cm at 36 months (Figure 2c). Mean heights of 141.69 and 78.59 cm were recorded for K. anthotheca and K. ivorensis, respectively and ranged from 113.02 to 179.92 cm and 61.29 to 94.94 cm, respectively. Differences between provenance mean height of trees ranged from 75.86 (Bobiri) to 179.92 cm (Akumasi Dumasi) and 113.27 (Bobiri) to 206.86 cm (Akumasi Dumasi) at the dry forest and the moist evergreen forest type, respectively, at 36 months. The variation in height growth between provenances and families and their interaction with the different ecological regions were highly significant (Table 2). The over all mean of the mahogany trees at the 3 sites were 266.61, 155.50 and 121.61 cm for Bobiri (moist semideciduous forest), Manso Amanfi (moist evergreen forest) and Afram-Headwaters (dry forest), respectively.

Table 2. Analysis of variance results for height, diameter and height to first fork (crown height) for ecological region, provenance and family of K. ivorensis and K. anthotheca 36 months after planting in the field. Growth Source of Variation Indices ______d.f. F-value P-value

Height Ecological region 2 230.88 <0.001 Species 1 31.13 <0.001 Provenance 6 26.82 <0.001 Family 21 2.61 0.032 Family x E.R1. 43 2.47 <0.001 Error 142 Mean square error 1844.950 Diameter (at 10cm) Ecological region 2 108.52 <0.001 Species 1 35.41 <0.001 Provenance 6 47.70 <0.001 Family 21 1.95 0.012 Family x E.R. 43 7.05 <0.001 Error 142 Mean square error 59.68 Crown height Ecological region 2 70.84 <0.001 Species 1 12.71 <0.001 Provenance 6 6.73 <0.001 Family 21 1.47 0.097 Family x E.R. 43 4.57 0.001 Error 142 Mean square error 585.260

1E.R. = Ecological Region Provenance = Akwasiho Abofour Akumasi-Dumasi

Boabeng-Fiema Bobiri Amantia Agona-Wasa

450

400 (a) 350

300 )

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0 G1 G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 G24 G25 G26 G27 G28 Family Planting (Bobiri) 250

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)

150 t ( c m c t ( h

i g 100 e H

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0 G1 G2 G3 G4 G6 G7 G8 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 Family Planting (Manso) 250

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0 G1 G2 G3 G4 G6 G7 G8 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 G27 Family planting (Afram Headwaters) Figure 2. Height of mahogany provenances and families 36 months after planting in the field (G1 to G17 is K. anthotheca and G18 to G28 K. ivorensis) at (a) Moist semideciduous Forest Site (b) Moist Evergreen Forest Site and (c). Dry Semideciduous Forest Site. Mean ± standard error.

The trend of variation in diameter growth was not different from that of height growth. Diameter (at 10 cm) growth of the African mahogany trees planted at Bobiri ranged between 18.9 and 62.68 mm at 36 months (Figure 3a). Variation in diameter between families were significant (P = 0.005). Differences in diameter between provenances were significantly high (P < 0.001) at the 36 month assessment. Within the Bobiri trial, family mean diameter ranging from 35.74 to 62.68 mm and 18.90 to 46.02mm were recorded at the 36 months for K. anthotheca and K. ivorensis, respectively. At Afram-Headwaters, the dry forest area the mean diameter ranged from 11.08 to 43.50 mm (Figure 3b) and 13.67 to 43.50 mm between families and provenances at the 36 months, respectively. The mean family diameter of K. anthotheca was between 25.37 and 43.50 mm whilst that of K. ivorensis was between 11.07 and 17.87 mm at the Afram-Headwaters trial. The different ecological regions where the experiments were established also affected on the diameter growth significantly Table (2). At the third planting site (in the moist evergreen forest [Manso]), the diameters ranged from 20.25 (Bobiri) to 47.35 mm (Akumasi-Dumasi) and 14.46 (G19) to 47.35 (G14) mm (Figure 3c). Within the Manso trials families of K. anthotheca mean diameter ranged from 28.16 to 47.35 mm and K. ivorensis from 14.45 to 27.01 mm. Mean diameter for the 3 trials were 27.2, 33.5 and 44.1 mm for Afram-Headwaters (dry forest), Manso Amanfi (Moist evergreen forest) and Bobiri (moist semideciduous forest), respectively.

Provenances = Akwasiho Abofour Akumasi-Dumasi

Boabeng-Fiema Bobiri Amantia Agona-Wasa 80

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50 ) o f t r e e s e f e t r o )

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s 45

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0 G1 G2 G3 G4 G6 G7 G8 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 G27 Family Planting (Afram Headwaters) Figure 3. Diameter of mahogany provenances and families 36 months after planting in the field (G1 to G17 is K. anthotheca and G18 to G28 K. ivorensis) at (a) Moist Semideciduous Forest Site (b) Moist Evergreen Forest Site and (c). Dry Semideciduous Forest Site. Mean ± standard error.

Families height to first fork (crown height) ranged from 114.47 to 241.79 cm at 36 months after planting at Bobiri (Figure 4a). The analysis of variance revealed no significant differences for both families and provenances at the 36 months at Bobiri. K. anthotheca and K. ivorensis recorded mean height of 172.37 to 154.55 cm, respectively. With the dry forest stand at Afram-Headwaters, provenances recorded significant differences in crown height at the 36 month assessment (P < 0.001) but family differences were not significant (P = 0.331). The crown height at Afram-Headwaters varied from 61.29 to 147.04 cm and 69.56 cm (Bobiri) to 141.05 (Akumasi-Dumasi) between families (Figure 4c) and provenances, respectively, at the 36 month. The mahogany trial that we established at Manso in the moist evergreen forest type had crown heights ranging from 81.67 to 152.52 cm (Figure 4b) and 102.06 (Bobiri) to 152.52 cm (Akumasi-Dumasi) for families and provenances, respectively. Pooled data from the three different ecological regions where our experiments were established revealed high significant differences (Table 2) between provenances planted at different sites with plants at Bobiri having superior crown height followed by Manso. Afram- Headwaters seedlings had the shortest crown heights. The mean crown height of the entire mahogany stand at the 3 ecological regions were 102.58, 119.64 and 165.36 at Afram- Headwaters (dry Forest), Manso Amanfi (Moist evergreen forest) and Bobiri (moist semideciduous forest) respectively.

Provenance Akwasiho Abofour Akumasi-Dumasi

300 Boabeng-Fiema Bobiri Amantia Agona-Wasa (a) 250

200

150

100 Height to first fork ( cm ) cm ( fork first to Height

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0 G1 G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 G24 G25 G26 G27 G28 Family Planting (Bobiri)

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rk ( c m ( c rk 100

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0 G1 G2 G3 G4 G6 G7 G8 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 G28 Family Planting ( Afram HeadWaters) Figure 4. Height to first fork of mahogany provenances and families 24 and 36 months after planting in the field (G1 to G17 is K. anthotheca and G18 to G28 K. ivorensis). (a) Moist Semideciduous Forest Site (b) Moist Evergreen Forest Site and (c). Dry Semideciduous Forest Site. Mean ± standard error.

3.2 Hypsipyla attack

Hypsipyla attack, as defined by Floyd and Hauxwell (2001), Wagner et al., (1991), Newton et al., (1993), Grijpma (1976) and Roberts (1966) was recorded in all provenances and families of K. anthotheca and K. ivorensis at all the planting sites in the 3 ecological regions. The mahogany stand we established at Bobiri (moist semideciduous forest) recorded attack percentage ranging from 41.3 to 94.4 % between families (Figure 5a) and 41.3 (Bobiri) to 86.7 % (Akumasi-Dumasi) between provenances at 36 months measurement. Highly significant differences were recorded between provenances but the differences between families were not significant (P = 0.001) and (P = 0.477) for provenance and families, respectively. Attacks on K. anthotheca ranged from 62.2 to 91.1% and that of K. ivorensis ranged from 41.3 to 94.4%. The experiment at Manso-Amanfi (moist evegreen forest) recorded mean percentage attack varying from 9.7 to 87.2% between families (Figure 5b) and 15.2 (Bobiri) to 83.1% (Akumasi-Dumasi) between provenances at the 36 months assessment. Differences between both families and provenances were highly significant (P < 0.001). The attacks in the K. anthotheca ranged from 40.6 to 87.2% and that of K.ivorensis varied from 9.7 to 28.5%. Differing levels of attacks were recorded at the Abofour (dry forest) experiment during the 36 month assessment. Hypsipyla attack varied from 9.7 to 90.0% between families at 36 month data collection (Figure 5c). Within the same period the attacks recorded on provenances ranged from 22.2 (Bobiri) to 90.0% (Akumasi-Dumasi). High significant differences between families (P < 0.001) and provenances (P < 0.001) were recorded. The interaction of the families with the different ecological regions significantly affected the levels of shoot borer attack on trees (Table 3).

Table 3. Analysis of variance results for percentage of tress attacked, number of branches per tree, number of fresh attack and length of dieback for ecological region, provenance and family of K. ivorensis and K. anthotheca 36 months after planting in the field. Shoot borer attacked Source of Variation Indices ______d.f. F-value P-value Percentage of trees attacked Ecological region 2 82.55 <0.001 Species 1 6.21 0.015 Provenance 6 39.12 <0.001 Family 21 2.09 0.006 Family x E.R1. 43 6.11 <0.001 Error 142 Mean square error 227.352 Number of branches Ecological region 2 23.52 <0.001 Species 1 12.71 0.001 Provenance 6 12.06 <0.001 Family 21 1.37 0.141 Family x E.R. 43 2.10 0.001 Error 142 Mean square error 1.021 Fresh attack Ecological region 2 29.65 <0.001 Species 1 7.83 0.001 Provenance 6 18.41 <0.001 Family 21 1.87 0.019 Family x E.R. 43 3.54 <0.001 Error 142 Mean square error 0.571 Length of dieback Ecological region 2 9.19 <0.001 Species 1 21.83 <0.001 Provenance 6 17.10 <0.001 Family 21 0.88 0.618 Family x E.R. 43 1.70 0.011 Error 138 Mean square error 143.400

1E.R. = Ecological Region

Provenance = Akwasiho Abofour Akumasi-Dumasi

120 Boabeng-Fiema Bobiri Amantia Agona-Wasa

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0 G1 G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 G24 G25 G26 G27 G28 Family Planting (bobiri )

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e 40 r e r T

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0 G1 G2 G3 G4 G6 G7 G8 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 G27 Family Planting (Afram Headwaters) Figure 5. Differing percentage of trees attacked by Hypsipyla per provenances and families 36 months after planting in the field (G1 to G17 are K. anthotheca and G18 to G28 K. ivorensis) at (a) Moist Semideciduous Forest Site (b) Moist Evergreen Forest Site and (c). Dry Semideciduous Forest Site. Mean ± standard error.

3.3 Sprouting in response to attack

The number of shoots sprouted in response to Hypsipyla attack differed between families and provenances. The Bobiri experiment had shoots sprouted in response to Hypsipyla attack ranging from mean 2.07 to 5.43 between families. Between provenances number of shoots sprouted varied from 2.07 (Agona-Wasa) to 4.88 (Akumasi-Dumasi). The differing levels of branching were not significant at 36 months (P = 0.27) between families. On the other hand, provenance effect on branching were highly significant (P = 0.023) within the Bobiri stand. Families and provenances impacted on branching characteristics of the mahogany trees in our experiment at Manso-Amanfi. The mean number of branches ranged from 1.00 to 4.99 between families. Between provenances means ranged from 2.12 (Bobiri) to 3.49 (Akumasi- Dumasi). Family and provenance differences were highly significant (P < 0.001) at 36 months. At the dry forest area in Abofour, variation between families and provenances were observed in the number of branches per tree resulting from Hypsipyla attack. Observations of families revealed numbers of sprouts ranging from 1.00 to 4.39. Provenances number of sprouts ranged from 1.55 (Bobiri) to 4.39 (Akumasi-Dumasi). Differences between both families and provenances were highly significant (P < 0.001). The ecological regions where the experiments were established interaction with families had profound effect of sprouting characteristics on the trees, differing significantly (Table 3).

Fresh attack frequency and length of dieback assessed were also significantly affected by both family and provenances as was their interaction with ecological regions (Table 3). At the moist semideciduous stand, Hypsipyla larval fresh attack frequency ranged from 0.33 to 1.22 and from 0.00 to 1.69 for provenances and families, respectively. There were a highly significant differences (P <0.001) between Hypsipyla fresh attacks on K. anthotheca and K. ivorensis with mean attack of 1.07 and 0.65, respectively. Mean Hypsipyla larval fresh attack frequency at the moist evergreen stand were 2.36 and 0.66 for K. anthotheca and K. ivorensis, respectively. Provenances and families varied in fresh attack frequency levels ranging from 0.66 to 3.00 and 0.00 to 3.67, respectively, at the moist evergreen experiment at 36 month. At the dry forest stand, K. anthotheca and K. ivorensis had mean fresh attack of 0.10 and 1.81, respectively. Hypsipyla larval fresh attack frequency for provenances and families ranged from 0.00 to 1.89 and 0.00 to 3.17, respectively. The length of dieback resulting from Hypsipyla attacks varied from 5.00 to 39.74 cm, 2.86 to 25.75 cm and 0.00 to 31 cm for provenances at the moist semideciduous, moist evergreen and dry semideciduous forest stands, respectively. The differences between families with respect to length of dieback were significant (P = 0.001 and (P = 0.04) at the dry forest experiment and moist evergreen stands, respectively. The length of dieback ranged between 2.33 and 47.34 at the moist semideciduous experiment. K. anthotheca and K. ivorensis had mean die back length of 26.03 and 8.44 cm, respectively, at the moist semideciduous experiment, 16.47 and 2.86 cm, respectively, at the moist evergreen stand, and 16.60 to 0.00 cm, respectively, at the dry forest stand.

4.0 Analysis and interpretation of the data and results

The pronounced variation in growth of the different provenances and families of the 2 African mahoganies within and between the 3 ecological regions were attributable to both inherent genetic traits and their interaction with the environment. The results of tree height growth from the moist semideciduous forest stand recorded relatively better height compared to the moist evergreen and dry semideciduous forest stands (Figure 2) in spite of the high Hypsipyla attack in the former stand. The contrasting height growth characteristics exhibited by the provenances was distinctly clear in the field with the family mean of (G14) originating from Akumasi-Dumasi provenance of K. anthotheca being superior within all the 3 ecological regions (mean height of G14 were 385, 206 and 180cm at moist semideciduous, moist evergreen and dry semideciduous forest types, respectively). The difference in growth between the different ecological regions was similar to the observations made when Milicia species (Iroko), another important native timber species was planted in these forest types (Adu-Bredu et al., 2000). The predominantly allogamouse mating system of mahogany (Lemes et al., 200; Hawthorne, 1990) tend to perpetuate genetic variation within and between populations. Studies on the Central American mahogany have identified significant levels of genetic variation in growth between families and provenances (Newton et al., 1999, 1998; Cornelius and Watt, 2003). The genetic diversity within the Central American mahoganies have been confirmed by molecular analysis of the genetic structure of the populations (Lemes et al., 2003; Novick et at., 2003; Cespedes et al., 2003) but this current paper is the first study considering the provenance selection of the African mahogany within the native range of its distribution.

All 3 growth indices (height, diameter and crown height) we assessed in this study exhibited strong genetic influences of provenances and families. The 4 K. anthotheca provenances which had representative in all 3 experimental sites in the different ecological regions recorded height growth in the order of Akumasi-Dumasi > Aboufour > Boabenfiema > Akwasiho in the moist semideciduos and dry semideciduos forest types. However, in the moist evergreen forest type, the Akwasiho provenance was second to the Akumasi-Dumasi in a similar order. The consistent dominance in both height and diameter of K. anthotheca families G14 and G12 attest to the possible genetic superiority of these families. However the inability of families G7 (Abofour origin) and G16 (Boabeng-Fiema origin) to maintain their superior growth in all 3 sites might indicate that they had a stronger genetic x environment influence.

The extent of genetic variation within the K. ivorensis families and the inconsistencies in growth with their interaction at the different forest types indicated that they are more prone to succumb to environmental factors compared to the K. anthotheca. The Bobiri provenance which was represented at all 3 sites had the family G23 recording the lowest growth in both diameter and height at the moist semideciduous forest but had the best height growth in both the dry semideciduous and moist evergreen forest types. The K. ivorensis provenance from Amantia which was planted only in the moist and dry semideciduous forest experiments performed relatively better with family G27 having elite trees.

The results of the height to first fork (crown height) growth from the moist semideciduous forest site when analyzed separately showed no significant differences between the provenances as well as families, though there were significant differences observed in both the total tree height and diameter growth. The variation in the height to first fork growth at the dry semideciduous forest and the moist evergreen forest types were significant. Specific reason cannot be assigned for the differences but Hypsipyla attack causing branching of mahoganies at the sapling stage was higher at the moist semideciduous forest than at the other 2 sites. The likelihood of Hypsipyla attack is affected by the tree size with the height range most susceptible between 1.5 and 3 m (Mo et al., 1997a; Morgan and Suratmo, 1976). Trees less than 1.5 m tall tend to escape Hypsipyla attack in a mahogany stand which might have caused the variation to the height to first fork (Mo et al., 1997a; Gara et al., 1973). Not withstanding the relative insignificant differences between the families planted at the moist semideciduous forest, the families G2, K. anthotheca of Akwasi origin and G21, K. ivorensis of Bobiri origin recorded the superior crown height though they could not maintain this trait in the dry semideciduous forest and the moist evergreen forest types. However, families G7, G12, and G14 sustained their relatively high crown height in all 3 ecological regions. Moreover, it is abundantly clear from the results that the family interaction at the different ecological regions impacted the crown height growth of all families but K. ivorensis families tended to be influenced more by their interaction with the environment. K. ivorensis distribution is naturally restricted to the moist forest whereas K. anthotheca are naturally established in all forest types in Ghana (Hall and Swain, 1981).

The fact that Hypsipyla attack was recorded on all provenances and all families at all 3 experimental sites for the 2 African mahoganies at the 36 month trees establishment in the field illustrates the importance of this pest in mahogany plantations in Ghana. The average percentage attack of 82.84 and 73.32% recorded on K. anthotheca and K. ivorensis, respectively at the moist semideciduous experimental plot compares to H. grandela attacks recorded on Swietenia macrophylla and Cederal odorata within a 3-year study period (Newton et al., 1998). The plot of our experiment in the moist evergreen forest zone recorded 64.27 and 15.20% for K. anthotheca and K. ivorensis, respectively, while in the dry forest 67.50 and 24.60% were recorded for the same species, respectively. A number of other research studies have reported similar trends of Hypsipyla destruction in mahogany stands. Yamazaki et al. (1992) reported attacks of up to 98% and 49% in C. odorata and S. macrophylla stands respectively within 16 months after planting in the field in Peru. In Trinidad, 47% and 53% were recorded on C. odorata and S. macrophylla, respectively, within the first 24 months in the field (Ramnarine, 1992). The other studies recorded cumulative attacks whilst we are presenting the attacks recorded only at the 36 months assessment. The findings of these studies emphasize the threat of Hypsipyla to successful mahogany plantations development in it natural range of distribution (Atuahene, 2001).

Our study reveals the high degree of provenance variation in incidence of Hypsipyla on African mahoganies at the different ecological regions in Ghana’s high forest. Khaya anthotheca provenance from Akumasi-Dumasi, recording the highest attack (86.67%) but at the family level K. ivorensis, G23 from Bobiri recorded the highest percentage attack (94.44%) at the moist semideciduous stand. At the moist evergreen experimental stand the Akumasi-Dumasi Khaya anthotheca provenance recorded the highest attacks (83%) while at the family level, G13 from Abofour provenance had the highest attack. The dry forest area recorded high attacks on K. anthotheca from Akumasi-Dumasi both at the provenance and family levels. We observed that trees which had dominant height growth recorded the highest attack similar to the observations made in comparable studies (Newton et al., 1999; Mo et al., 1997b; Whitemore et al., 1978). In spite of the high attacks on the fast-growing trees, they seem to possess the ability to recover better from attack than the slow-growing trees. This is demonstrated by K. anthotheca provenances from Akumasi-Dumasi and Afram headwaters which consistently recorded the best performance with regard to the growth indices (mean total height, mean diameter and mean height to first fork) across all 3 ecological regions. The Akumasi-Dumasi provenance had height of 257.29 cm, diameter of 49.51 mm and height to first fork of 159.64 cm which was followed by the Afram headwaters provenance with height of 213.59 cm, diameter of 41.40 mm and height to first fork of 141.38 cm. There is limited information on the African mahogany susceptibility to attacks in its native range (Atuahene, 2001) but data from the Central American mahogany suggest that tree vigor partly contribute to its ability to tolerate attack (Newton et al., 1999; Ramnarine 1992; Sanchez et al., 1976).

K. anthotheca, which is naturally established in all the forest ecological regions of Ghana, seems to grow faster and attract relatively more shoot borer attacks but in most cases have an inherent ability to recover better compared to K. ivorensis. The length of die back was consistently higher in K. anthotheca than K. ivorensis but the former still had dominant total tree height. Similar trends were observed with the fresh laval incidence when damaged loci per tree were recorded.

Genetic variation in production of multiple shoots in response to Hypsipyla attack which reduces the economic value of mahogany was clear in our results. Family G11 responded to attack with the highest number of shoots at both the moist semideciduous and the moist evergreen forest stands with 5.4 and 5.0, respectively, and was second at the dry forest type with 3.84 shoots. Cornelius and Watt (2003) made similar observation with Cedrela provenances and attributed consistent branching to higher number of attacks and inherent tendency to branch in response to attack by certain genotypes. Our results strongly support the data that further screening of larger number of provenances could lead to identifying pest tolerant candidates of these species for sustainable plantations production. Family G14 and G12 which were from the Akumsi-Dumasi and the Afram headwaters provenances respectively recorded relatively high number of branches (4.3 and 3.6, respectively) but their superior growth to first fork point to the possibility of inherent ability of natural pruning of some branches to improve form (Opuni-Frimpong, 2000).

5.0 Conclusions

The significance of our studies is that there is substantial variation in the mahogany populations in Ghana to Hypsipyla attack. Different provenances and individual trees within families of these provenances of Khaya anthotheca and K. ivorensis had varied ability to tolerate Hypsipyla shoot borer. Different genotypes of mahogany will grow at different rate in different ecological zones which could affect their ability to tolerate the mahogany shoot borer attack. Individuals in K. anthotheca families, especially G14, G12 and K. ivorensis family G25 which demonstrated superior height to first fork despite persistent attack could be propagated for demonstration plantations.

6.0 Recommendations

It is recommended that careful attention is taken in matching genotype to the environment in which they are suited since they appear to be a critical component factor, especially for K. ivorensis. Further incorporating mahogany in plantations may be feasible in the near future with continued research to develop better silvicultural systems and to match those systems to specific species and provenances of mahogany to enhance mahogany’s ability to tolerate Hypsipyla attacks.

7.0 Implications for practice

The variation in mahogany responses to Hypsipyla shoot borer attack for the different species and provenances of the different ecological types in Ghana suggest that tolerance to Hypsipyla shoot borer is controlled by inherent genetic traits. It was clear in the planations that individuals within families have their own substantial genetic differences suggesting that propagation of tolerant trees should be limited to genotypes witin families rather than families. To understand the genetic structure of the isolated populations of mahogany in Ghana, and to support data available in this study, further research will have to consider looking at the molecular level diversity between and within natural populations. This could initiate steps towards mapping tolerance genes in mahogany to the Hypsipyla shoot borer leading to in situ and ex situ conservation of elite trees and superior genes.

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Major Research 2.

Relative susceptibility of four species of African mahogany to the shoot borer Hypsipyla robusta (Lepidoptera: Pyralidae) in the moist semideciduous forest of Ghana.

E. Opuni-Frimponga,*, D.F. Karnoskyb, A.J. Storerb, E.A. Abeneyc and J.R. Cobbinaha

a Forestry Research Institute of Ghana, Kumasi, Univ. Box 63, Kumasi Ghana b School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan, 49931, USA c Kwame Nkrumah Universities of Science and Technology, Kumasi, Ghana E-mail address: [email protected] and [email protected] (E. Opuni-Frimpong)

Abstract Attempts to establish large-scale plantations of African mahoganies for sustainable timber production have been hampered by the shoot borer Hypsipyla robusta Moore (Lepidoptera: Pyralidae). We examined the relative susceptibility of four mahogany species, two of Khaya (K. ivorensis & K. anthotheca) and two of Entandrophragma (E. angolense & E. utile) to H. robusta attack. Seeds were obtained from 2 parent trees of K. ivorensis, 2 parent trees of K. anthotheca, 3 parent trees of E. angolense, and 1 parent tree of E. utile. The research was conducted in a moist, semi-deciduous forest zone in Ghana and used a randomized complete block design. Each seed source was represented in the field by 20 seedlings in each of four blocks. Tree height, diameter and clear trunk height (tree height from ground to the first branching in response to H. robusta attack) were measured 15, 18, 21, and 24 months after out-planting of the seedlings in the field. Hypsipyla robusta damage was assessed by counting the number of shoots attacked, the number of dead shoots, and the number of fresh shoots with larval activity. The relative susceptibility from most to least of the four species to H. robusta attack was: K. anthotheca> K. ivorensis> E. angolense> E. utile. At 15 months, the mean number of shoots attacked per tree by H. robusta ranged from 0 on trees from an E. angolense seed source to 5 on trees from a K. anthotheca seed source. At 24 months, the mean number of shoots attacked per tree ranged from 1 on trees from an E. utile seed source to 3.6 on trees from a K. anthotheca seed source. The measurement of clear trunk height revealed that K. ivorensis and K. anthotheca were most preferred by H. robusta and started branching at a low height, but they exhibited an increased clear trunk height over time attributable to self-pruning. It was also evident that as K. anthotheca grew taller, the number of H. robusta attacks per tree declined. This suggests that selection of genotypes and species that are tolerant of H. robusta attack based on infestation of young plants may not be appropriate. Genetic factors more completely reflecting the response of the different species and genotypes to H. robusta attack are likely to manifest themselves at later stages in the plant’s growth. Keywords: Meliaceae, Khaya, Entandrophragma, African mahogany, Hypsipyla, susceptibility, tolerance

1.0 Introduction

The mahogany shoot borers, Hypsipyla species (Lepidoptera: Pyralidae), are among the most economically significant insect pests in tropical forestry. The two most important species are H. robusta in Africa and the Asia/Pacific region and H. grandella (Zeller) in the Americas (Entwhistle, 1967). The principal damage caused by these species is from larval feeding in apical shoots. Repeated attack of the main leader results in epicormic branching and stunted growth, both of which affect the quality of timber produced (Wagner et al., 1991; Dupuy, 1985). Despite significant research and management efforts, previous attempts to manage Hypsipyla spp. have largely been unsuccessful (Wagner et al., 1998; Newton et al., 1993; Mayhew and Newton, 1998; Hauxwell et al., 2001). However, the prospects for reducing the impacts of Hypsipyla spp. have increased with the identification within Swietenia macrophylla and Cedrella odorata of partial resistance to attack by Hypsipyla grandella in Central America (Newton et al., 1993, 1998; Watt et al., 2001).

The Khaya, Entandrophragma, Guarea, and Lovoa spp. (Meliaceae), are considered to be among the most valuable tropical timber species world-wide. These species are found naturally throughout the moist semideciduous and dry forest zones of West Africa (Hawthorne, 1995; Hall and Swaine, 1981). Timber from native mahoganies, especially Khaya and Entandrophragma spp., contribute significantly to the timber exports of the West African nation of Ghana. On average, mahogany contributes approximately 15-30 % of timber exports from Ghana (Atuahene, 2001). Unfortunately, this has led to the over exploitation of these species in the native forests of Ghana. It has been projected that the mahoganies would face commercial extinction by 2007 at the rates of exploitation that occurred in the late 1980s (Alder, 1989).

Despite the decline of mahoganies in the West Africa subregion, demand for African mahogany is anticipated to increase as a result of the decline in supply of mahogany timber from Southeast Asia and South America (Atuahene, 2001; Elliot and Pleydell, 1992). An increase in demand will threaten the viability and sustainability of mahoganies in areas where significant volumes of these species are still found. Measures to ensure the sustainable production of mahoganies into the future include the establishment of the Meliaceae in plantations, and more stringent regulation of timber volume removal so that it reflects the rate of replacement by natural or managed regeneration.

Most mahogany plantations that have been established in West Africa have failed due to attack by H. robusta (Atuahene, 1972, 2001; Robert, 1966; Entwistle, 1967; Grijpma, 1976). H. robusta has been recorded in West Africa on Khaya spp., Entandrophragma spp., Carapa procera, C. grandiflora, Lovoa trichiniodes, and Swietenia macrophylla (Robert, 1968; Wagner et al., 1991; Newton, 1993).

The objective of this study was to compare the extent of shoot borer damage in four species of African mahogany with a view to determining plant characteristics that are associated with tolerance to shoot borer attack. 2.0 Applied methodology.

2.1 Experimental Design

The seeds from eight sources, representing four mahogany species (Table 1) were grown and maintained at the Forestry Research Institute of Ghana (FORIG) central nursery at Mesewam in the moist semi-deciduous forest zone of Ghana. Each mahogany species was represented by one to three seed sources (Fig. 1). Ten days after germination, seedlings were transplanted into polythene bags (17.5 cm by 2.5 cm) filled with topsoil. Weeds were removed by hand throughout the nursery stage. Eighty seedlings from each seed source were established in field plantings. Seedlings were transferred to the field when they were 35-40 cm tall. The field planting was laid out in a complete randomized block design with four blocks. Each block was divided into eight plots, and within each plot, 20 seedlings from one of the seed sources were planted in four rows and five columns at 0.5 meters spacing. Hence each block had 20 seedlings from each of the eight seed sources, assigned to plots within blocks at random.

Table1: Sources of seeds from four African mahogany species used in tests of tolerance of damage by the shoot borer Hypsipyla robusta.

Code Name Species Seed source Forest Type

Ka1 Khaya anthotheca Abofour Dry forest Ka2 K. anthotheca Afram Headwaters Dry forest Ki1 K. ivorensis Bobiri Moist forest Ki2 K. ivorensis Pra Anum Moist forest Ea1 Entandrophragma angolense Abofour Dry forest Ea2 E. angolense South Fomanso Moist forest Ea3 E. angolense Jimira Moist forest Eu1 E. utile Abofour Dry forest

1 2

3 5 ٭ 6 4

Fig. 1. Rain forest of Ghana with seed collection points; 1. Afram headwaters, 2. at (٭) Abofour, 3. Bobiri, 4. Pra Anum, 5. South Fumanso, and 6. Jimira, Study site Mesewam where our trials were established.

2.2 Measurements

Data were collected at 15, 18, 21, and 24 months after planting in the field. At each date, 10 trees randomly selected from each seed source in each block were assessed for damage by H. robusta. The measurements taken were total tree height, diameter at breast height (dbh) i.e., measured at the standard height of 1.3 meters, clear trunk height (height to first fork [Cornelius, 2000], commercial height [Cornelius and Watt, 2003], crown height [Helms, 1998]), and total number of shoots sprouted in response to H. robusta attack. Sprouted shoots were counted and attributed to Hypsipyla attack when there was evidence of attack and dieback with new shoots sprouting for recovery. The damage by H. robusta was assessed by recording the total number of shoots attacked and the total number of dead shoots on the sampled trees. Percentage of trees attacked by H. robusta was also determined.

2.2 Data analysis

Analysis of variance (ANOVA) of a randomized block design was used to test the significance (P<0.05) of differences between seed sources for each of the parameters measured. If overall effect of seed source was significant, a priori user defined contrasts were performed to make the following six orthogonal comparisons between seed sources: 1) all Khaya seed sources combined compared with all Entandophragma seed sources combined, 2) the two K. anthotheca seed sources combined compared with the two K. ivorensis seed sources combined, 3) the three E. angolese seed sources combined compared with the one E. utile seed source, 4) the K. anthotheca seed source one compared with K. anthotheca seed source two, 5) the K. ivorensis seed source one compared with K. ivorensis seed source two, and 6) an overall comparison among the three E. angolese seed sources. In addition, we report the Least Significant Difference value associated with post hoc pairwise comparisons among all possible combinations of seed lots. All analyses were carried out using SPSS 11.0 for Windows (SPSS, 2005).

3.0 Presentation of data

3.1 Tree Growth

Generally, there was a positive growth increment in the size indices measured (height, diameter and clear trunk height) throughout the study period (Figure 2). However there was a reduction in growth in height and diameter of E. utile (Eu1) at 24 months as a result of Hypsipyla-related dieback. E. angolense seedlots from Abofour and South Fomanso also recorded slight reductions in diameter at 21 months due to dieback from Hypsipyla attack experience during 18 month and beyond (Table 3 and Fig. 5). Defined contrasts following ANOVA testing the differences in height and diameter at 15 and 24 months showed significant differences between Khaya spp. and Entandrophragma spp. (Table 3). Khaya spp. were taller and had greater diameters than Entandrophragma spp. at both times tested. Differences in height and diameter between the two Khaya species, between the two Entandrophragma species, and among seedlots within each species were not significant (Table 2). Differences in crown heights were only significantly different for the comparisons between the two K. ivorensis seedlots after 15 months. This difference was not significant after 24 months (Table 2).

Table 2: Percentage of trees attacked by Hypsipyla at 15, 18 21, and 24 months from eight different seed sources (± SE).

Tree species 15 months 18 months 21 months 24 months

Khaya anthotheca 1 78.3 ± 8.5 81.8 ± 7.9 86.27 ± 11.9 87.78± 5.8 Khaya anthotheca 2 84.8 ± 6.0 78.4 ± 7.1 75.0 ± 5.7 87.50± 6.0 Khaya ivorensis 1 65.4 ± 3.7 80.8 ± 2.1 72.7 ± 2.7 75.86± 2.4 Khaya ivorensis 2 61.8 ± 2.2 82.6 ± 4.2 56.5 ± 5.1 68.4 ± 1.2 Entandrophragma angolense 1 10.0 ± 0.8 9.0 ± 0.5 16.00 ± 0.9 33.3 ± 1.4 Entandrophragma angolense 2 0.0 ± 0.0 18.2 ± 2.0 27.3 ± 2.3 16.7 ± 2.0 Entandrophragma angolense 3 0.00 ± 0.0 8.3 ± 0.8 9.1 ± 0.8 25.0 ± 1.5 Entandrophragma utile 1 0.00 ± 0.0 9.1 ± 0.8 10.00 ± 1 9.0± 0.8

4.0

3.5

3.0

2.5 15M onths 18M onths 2.0 21M onths 1.5 24M onths Mean height (m) height Mean 1.0

0.5

0.0 Ka1 Ka2 Ki1 Ki2 Ea1 Ea2 Ea3 Eu1 Species

4.5

4.0 15Months 3.5 18Months 3.0 21Months 2.5 24Months 2.0 1.5

Mean diameter(cm) Mean 1.0 0.5 0.0 Ka1 Ka2 Ki1 Ki2 Ea1 Ea2 Ea3 Eu1 Species

3.0

2.5

2.0 15Months 18Months 1.5 21Months 24Months 1.0 Crown height (m) 0.5

0.0 Ka1 Ka2 Ki1 Ki2 species

Fig. 2. Growth of 4 species of mahogany from one or more seed sources each, 15 to 24 months after out-planting. (a) Mean height, (b) mean diameter at breast height (dbh) and (c) mean clear trunk height. Species codes: Ka – Khaya anthotheca, Ki - K. ivorensis, Ea – Entandrophragma angolense and Eu – E. utile are the different species of mahogany used in our studies. Least significant differences for post hoc pairwise comparisons are 0.93 cm for height, 0.90 cm for diameter and 0.79 cm for crown height. Error bars are for standard error.

3.2 Hypsipyla attack

The mean number of shoots attacked by Hypsipyla on the eight seed sources varied significantly among the four mahogany species (Fig. 3 and Table 3). The percentage of trees attacked for each seed source also varied (Table 2). At 15 months, 85% of the K. anthotheca from Afram headwaters (Ka2) were attacked by Hypsipyla, but only 10% of E. angolense from Abofour (Ea1), and none of the E. angolnse from Jimira (Ea2), South Fumanso (Ea3), and E. utile (Eu1) were attacked (Table 2). The relative susceptibility (from most to least) of the different species was: K. anthotheca > K. ivorensis > E. angolense > E. utile.

Table 3. P-values associated with user-defined contrasts for various growth indices of mahogany. Measurements were height, diameter at breast height and clear trunk height (height to first fork). Species codes: K – Khaya, E – Entamdrophragma, Ka – K. anthothca, Ki – K. ivorensis, Ea – E. angolense. See Table 1 for the seed sources codes.

Species Mean Height Mean DBH Mean Crown Ht

15 months 24 months 15 months 24 months 15 months 24 months

K vs E 0.000 0.000 0.000 0.000 * * Ka vs Ki 0.304 0.387 0.197 0.071 0.851 0.729 Ea vs Eu 0.065 0.076 0.176 0.143 * * Ka1 vs Ka2 0.401 0.438 0.573 0.966 0.729 0.577 Ki1 vs Ki2 0.896 0.622 0.208 0.091 0.043 0.156 Ea1vs Ea2 vs Ea3 0.242 0.600 0.600 0.314 * *

* Branching was not prominent in the Entandrophragmas so we did not make this comparison.

The seed sources that received the higher Hypsipyla attacks (Table 2) also recorded the greatest sprouting of multiple lateral shoots (Fig. 4). In general, Khaya spp. developed more multiple lateral shoots in response to Hypsipyla attack than did the Entandrophragma species and differed significantly (Figure 4 and Table 4). However, the number of sprouts of K. anthotheca decreased as the trees grew. K. ivorensis grown from seeds collected from Bobiri (Ki1) showed an increasing trend in number of sprouts in response to Hypsipyla attack except at 21 months where it had a decreased number of sprouts. The trend was similar to K. ivorensis collected from Pra Anum (Ki2) except that the number of sprouts decreased at 24 months. E. angolense seedlots from Abofour, South Fomansu, Jimra, and E. utile from Abofour seldom had more than one sprouted shoot per tree since they were seldom attacked by Hypsipyla. K. anthotheca had the largest number of dead shoots per tree, while K. ivorensis and E. angolense had fewer dead shoots throughout the experiment (Fig. 5).

6

5

4

15Months 18Months 3 21Months 24Months

2 Mean number of shoots attacked

1

0 Ka1 ka2 ki1 ki2 Ea1 Ea2 Ea3 Eu1 Species Fig. 3. Mean number of shoots attacked per tree from each species from 15 to 24 months after planting in the field. Species codes: Ka – Khaya anthotheca, Ki - K. ivorensis, Ea – Entandrophragma angolense and Eu – E. utile are the different species of mahogany used in our studies. Least significant difference for post hoc pairwise comparison is 1.19 cm. Error bars are for standard error.

Table 4. P-values associated with user-defined contrasts for various Hypsipyla damage indices in mahogany. Measurements were shoots attacked per tree, sprouted shoots per tree and dead shoots per tree. Species codes: K – Khaya, E – Entamdrophragma, Ka – K. anthothca, Ki – K. ivorensis, Ea – E. angolense. See Table 1 for the seed sources codes.

Species Mean shoots Mean sprouted Mean number of attacked shoots dead shoots

15 months 24 months 15 months 24 months 15 months 24 months

K vs E 0.000 0.000 0.000 0.000 0.000 0.000 Ka vs Ki 0.000 0.000 0.000 0.001 0.000 0.000 Ea vs Eu 0.957 0.600 1.000 0.788 1.00 0.648 Ka1 vs Ka2 0.569 0.063 0.844 0.072 0.325 0.026 Ki1 vs Ki2 0.458 0.050 0.308 0.041 0.939 0.226 Ea1vs Ea2 vs Ea3 0.008 0.035 1.000 0.037 1.00 0.023

8

7

6

5 15Months 18Months 4 21Months 24Months 3

Mean number ofshootsMean number sprouted 2

1

0 Ka1 Ka2 Ki1 Ki2 Ea1 Ea2 Ea3 Eu1 Species

Fig. 4. Mean number of shoots recorded on ten mahogany trees of each species sampled from 15 to 24 months after planting. Species codes: Ka – Khaya anthotheca, Ki - K. ivorensis, Ea – Entandrophragma angolense and Eu – E. utile are the different species of mahogany used in our studies. Least significant difference for post hoc pairwise comparisons is 1.68 shoots. Error bars are for standard error.

Defined contrasts for the number of attacks per tree, number of sprouted shoots per tree, and number of dead shoots per tree showed significant differences between seedlots of Khaya species and seedlots of Entandrophragma species (Table 4). Khaya species had significantly more attacked shoots, sprouted shoots, and dead shoots than Entandrophragma species. K. anthotheca had significantly more attacked shoots, sprouted shoots, and dead shoots than did K. ivorensis. At 24 months the difference in the number of dead shoots between the two K. anthotheca seedlots was significant, and at 24 months the difference in the number of sprouted shoots between the two K. ivorensis seedlots was significant. At both measurement times tested, the difference in the number of attacked shoots between the three E. angolense seedlots were significant, as were differences between these seedlots in the number of sprouted branches and the number of dead branches at 24 months.

4.5

4

3.5

3

2.5 15Months 18Months 21Months 2 24Months

1.5 Mean number of Dead shoots recorded

1

0.5

0 Ka1 Ka2 Ki1 Ki2 Ea1 Ea2 Ea3 Eu1 Species

Fig. 5. Mean number dead-shoots resulting from Hypsipyla attack recorded per tree from 15 to 24 months after planting in the field. Species codes: Ka – Khaya anthotheca, Ki - K. ivorensis, Ea – Entandrophragma angolense and Eu – E. utile are the different species of mahogany used in our studies. Least significant differences for post hoc pairwise comparisons is 1.54 number of shoots. Error bars are for standard error.

4.0 Analysis and interpretation of the data results

Hypsipyla attack was recorded on all the four species of mahogany used in the experiment. Thus, no evidence of complete resistance was observed in the K. anthotheca, K. ivorensis, E. angolense and E. utile sources evaluated in this study. Hypsipyla attack, however, was consistently lower on the Entandrophragma spp. as compared to the Khaya spp. At 15 months after planting in the field, E. utile and 2 sources of E. angolense had not been attacked by Hypsipyla, whereas over 60% and 75% of K. ivorensis and K. anthotheca, respectively. This demonstrated the apparent preference of Hypsipyla robusta in central Ghana for the Khaya species used in this study. In a similar study looking at the incidence of Hypsipyla grandella on Cedrella odorata and Swietenia macrophylla at week 10 after planting, C. odorata had 25% of trees attacked whilst S. macrophylla had no attack (Newton et al., 1998). By week 84, 77% and 74% of the S. macrophylla and C. odorata respectively had been attacked. On the other hand, in our study, the levels of attack on the Entandrophragma spp were consistently lower than for the Khaya spp. K. anthotheca was most susceptible to H. robusta attack followed by K. ivorensis. Production of forked stems, as indicated by a lower clear trunk height, was evident in K. anthotheca and K. ivorensis but not for E. angolense and E. utile. The Khaya spp. started branching as a result of Hypsipyla attack at a height between 1.0 and 1.5 m. However, this early branching/forking may be eliminated since the clear trunk height generally increased over time for the seedlots of K. anthotheca and of K. ivorensis. This characteristic of the Khaya spp. was attributed to self- pruning, supporting earlier observations on the effectiveness of pruning in mitigating Hypsipyla grandella attack on Swietenia macropylla King (Cornelius, 2000; Cornelius and Watt, 2003).

It is not known why Hypsipyla in central Ghana prefers the Khaya spp. Selection of host plants by oligophagous insects like Hypsipyla is often chemically mediated (Grijpma, 1976; Grijpma and Gara, 1970). For example, it was observed for Hypsipyla grandella, that the insects orient themselves to plants using chemoreception. If chemical differences are responsible for the variation in Hypsipyla attack on different species of Meliaceae, then possibilities exist for propagating non-preferred species (Grijpma, 1976). The results of our study suggest that at a young age, Hypsipyla shows a marked preference for Khaya spp. over Entandrophragma spp. This may be useful in future breeding programs but our study used only young trees, the results must be verified for older trees. In spite of the high susceptibility of the Khaya spp. to Hypsipyla, both Khaya spp. showed substantial height growth throughout the study period. Although it was the most heavily attacked species, K. anthotheca attained a size similar to the less susceptible K. ivorensis. In general, there was an increasing ability of the K. anthotheca to tolerate (reducing number of branches, increment in clear trunk height and total height) Hypsipyla attack as the trees aged and increased in height. This is consistent with observations on Swietenia macrophylla (Suratmo, 1977, Cornelius and Watt, 2003).

Although not examined directly in our study, environmental interactions may have influenced attack by Hypsipyla on the seed sources of Meliaceae used in this experiment. Species or genotype interactions with the environment may enhance or retard tree growth and pest attack. Grijpma (1976) suggested that big-leaf mahogany trees, S. macrophylla, growing in favorable sites grow relatively rapidly and consequently are better able to recover after attack by production of vigorous new apical shoots. Both K. anthotheca seed sources were from the dry forest and showed vigorous growth at the experimental site in moist forest type where frequent rainfall might have provided better conditions for plant growth. This might have contributed to the quick recovery after high incidence of Hypsipyla attack on K. anthotheca relative to the other species in this study. This suggests that selection for tolerant species solely on the basis of early infestation may not be appropriate.

The most important characteristics associated with Hypsipyla attack is the sprouting of multiple shoots of host plants in response to the attack (Grijpma 1976; Newton, 2003; Taveras et al., 2004). This leads to early forking and ultimately reduces the quality and quantity of timber produced. K. anthotheca recorded the highest number of shoots sprouting during the study period. However, there was a decrease in the shoot sprouting over the study period. This phenomenon appears to be one of the characteristics associated with tolerance of Meliaceae to Hypsipyla attack. K. ivorensis maintained high number of sprouted shoots with time, suggesting that its ranking as among the most susceptible species is accurate (Robert, 1966). The Entandrophragma spp., especially E. utile which generally had a single shoot, may be less attractive to Hypsipyla relative to the other species. E. utile ranks as among the most tolerant to Hypsipyla attack in this study. Higher apical dominance was demonstrated in the Entandrophragma species examined compared to the Khaya species because the former responded to attack with fewer apical shoots. However, lower growth rates of the Entandrophragma spp. could make K. anthotheca the preferred plantation species from a production standpoint. If pruning is a reasonable option for management (Cornelius, 2000; Newton et al., 1999), then the Khaya spp. could be brought through young stages via judicious pruning to keep the number of main stems to minimum.

Hypsipyla infestation on mahogany shoots almost always leads to dieback of the attacked shoots, causing considerable growth retardation and formation of numerous secondary shoots, and resulting in poorly formed trees unsuitable for timber production. Attacks on new shoots do not normally cause the death of trees, but in combination with attack on the older shoots and the main stem, they may sometimes kill the tree. In our study, this was an observation made on very few K. ivorensis, which commonly suffered serious stem mortality. This further supports previous listing of K. ivorensis as among the most susceptible Meliaceae species (Robert, 1966). K. anthotheca suffered the most attack of the growing shoots which led to dieback of most of its shoots. However, there was a decreasing trend in the dead shoots recorded, especially for K. anthotheca which suffered highest attack during the study period. The reason for this trend could be that as a tree ages its ability to survive Hypsipyla attack and recover improves.

The results of this study could be attributed to lack of preference by Hypsipyla to the Entandrophragma spp. or tolerance to Hypsipyla attack as exhibited in K. anthotheca seed sources used. It is evident that there is considerable variation in the tolerance of the Meliaceae species collected from different locations in Ghana’s forest zones. Thus, there is a need for more studies to screen for genotypes that are resistant to or tolerant of Hypsipyla attack. The natural pruning characteristics exhibited in the Khaya species may be a useful trait to exploit in selection of tolerant planting stock in the effort to reduce the impact of Hypsipyla on mahogany plantations.

5.0 Conclusions

It is evident that there is considerable variation in the susceptibility of Meliaceae from Ghana’s forest zones to attack by H. robusta. Relatively, the Khaya species were more susceptible to Hypsipyla shoot borer attack compared to the Entandrophragma species. When evaluated for potential as plantation stock, the susceptibility to attack of Khaya spp. than Entandrophragma spp. could be offset by the greater growth of Khaya spp. under open conditions. Faster growing mahogany trees attracted the highest number of Hypsipyla shoot borer attacks but in some cases these trees recovered and maintained superior tree form. The natural pruning exhibited in Khaya spp., especially K. anthotheca, may be useful to exploit in selection of tolerant planting stock to reduce the impact of H. robusta. The increase in tolerance (or resistance) over time in K. anthotheca suggested that selection for genotypes and species tolerant of H. robusta attack based on infestation of young plants may not be appropriate. Genetic factors more completely reflecting the response of the different species and genotypes to H. robusta attack may manifest themselves at later growth stages.

Bibliography

Alder, D. 1989. Natural forest increment, growth and yield. In: Ghana Forest Inventory Project Seminar Proceedings. (J.LG. Wong; ed) Ghana Forestry Commission/Overseas Development Administration. 29-30 March 1989. Accra, Ghana. 101 pp Atuahene S. K. N. 2001. The forest resource in Ghana and future direction of research on Hysipyla robusta Moore (Lepidoptera: Pyralidae) control in mahogany plantations. Proceedings of an international workshop on Hypsipyla shoot borers of Meliaceae, Kandy, Sri Lanka, 1996. ACIAR Proceedings No. 97 Canberra, Australia, pp 58-62. Atuahene, S. K. N. 1972. The major Entomological problems facing Ghana’s reforestation program. Seventh world forestry Congress.14-18 October, 1972, Buenos Aires, Argentina, 1587-1590. Cornelius, J. P. 2000. The effectiveness of pruning in mitigating Hypsipyla grandella attack on young mahogany (Swietenia macrophylla King) trees. For. Ecol. Manage. 148: 287-289. Cornelius, J.P. and Watt, A.D. 2003. Genetic variation in Hypsipyla-attacked clonal trial of Cedrella odorata under two pruning regimes. For. Ecol. Manage. 183: 341- 349 Dupuy, B. 1995. Mixed plantations in Cote d’Ivoire rain forest. Bois et forêts des Tropiques 245: 33-43. Elliot, G. and Pleydell, G. 1992. Report on marketing and utilisation of plantation species. Report for the Government of Ghana under assignment from the DFID. Unpublished. Entwistle, P. F. 1967. The current situation on shoot, fruit and collar borers of the Meliaceae. Proc. Ninth British Commonwealth Forestry Conference, Commonw. For. Inst., Oxford, pp 15 Grijpma, P. 1976. Resistance of Meliaceae against the shoot borer Hypsipyla with particular reference to Toona ciliata M. J. Roem.var Australia (f.V.Muell.) C.D.C. In: Burley, J., and Styles, B.T., (Eds.), Tropical Trees: Variation, Breeding, and Conservation. Academic Press, London, UK. pp. 69 - 78. Grijpma, P. and Gara, R. I. 1970. Studies on the shootborer Hypsipyla grandella (zeller): host selection behaviour, Turrialba 20: 233-240. Hauxwell, C., Varas, C. and Opuni-Frimpong, E. (2001). Strategies for control of Hypsipyla with entomopathogens. In: Floyd, F. and Hauxwell, C. (Eds.) Proceedings of an international workshop on Hypsipyla shoot borers of the Meliaceae, Kandy, Srilanka, 1996. ACIAR Proceedings No.97, Canberra, Australia, pp.131-139. Hawthorne, W. D. 1995. Ecological profiles of Ghana forest trees. ODA Tropical Forestry Paper No. 29. Oxford Forestry Institute, UK. 345 pp. Helms, J. A. 1998. The dictionary of forestry. CAB International/Society of American Foresters, USA Mayhew J. E. and Newton A. C. 1998. The Silviculture of Mahogany. CABI Publishing, Wallingford, U.K. Newton, A. C., Baker, P., Ramnarline, S. Messen, J. F. and Leaky R. R. B. 1993. The mahogany shoot borer: prospects for control. Forest Ecology and Management. 57: 301-328 Newton, A.C., Cornelius, J.P., Corea, E.A. and Watt A.D. 1998. Variation in attack by the mahogany shoot borer, Hypsipyla grandella (Lepidoptera: Pyralidae) in relation to host growth and phenology. Bull. of Ent. Res. 88: 319-326. Newton, A.C., Watt, A.D., Lopez, F., Cornelius, J.P., Messen, J.F. and Corea, E.A. 1999. Genetic variation in host susceptibility to attack by the mahogany shoot borer, Hypsipyla grandella (Zeller). Agric. For. Entomol. 1: 11-18 Roberts, H. 1968. An outline of the biology of Hypsipyla robusta Moore, the shoot borer of the Meliaceae (Mahoganies) of Nigeria; together with brief comments on two stem borers and one other Lepidopteran fruit borer also found in Nigerian Meliaceae. Commonwealth For. Rev. 47: 225-232. Roberts, H. 1966. A survey of the important shoot, stem wood; flower and fruit boring insects of the Meliaceae in Nigeria. Nigerian Forestry Information Bulletin. (New Series) No.15, 38 pp. Suratmo, F. G. 1977. Infestation of the leading shoots of mahogany (Swietenia macropylla King) by Hypsipyla robusta (Moore) in West Java, Indonesia. Proceedings, symposium on forest pest and diseases in Southeast Asia, April 20-23, 1976, Biotrop Special Publication 2, Bangor, Indonesia. pp. 121-132. Taveras, R., Hilje, L., Hanson, P., Mexzon, R. Carballo, M., and Navarros, C. 2004. Population trends and damage patterns of Hypsipyla grandella (Lepidoptera: Pyralidae) in a mahogany stand, in Turrialba, Costa Rica. Agriculture and Forest Entomology 6: 89-98. Wagner, M. R., Atuahene, S. K. M and Cobbinah, J. R. 1991. Forest Entomology in West Tropical Africa: Forest Insects of Ghana. Kluwer Academic Publishers, Dordrecht, Netherlands. Watt, A. D. Newton, A. C. and Cornelius, J. P. 2001. Resistance in mahoganies to Hypsipyla species-basis for integrated pest management. In: Floyd, F. and Hauxwell, C. (Eds.) Proceedings of an international workshop on Hypsipyla shoot borers of the Meliaceae, Kandy, Srilanka, 1996. ACIAR Proceedings No.97, Canberra, Australia, pp. 89-95.

Major Research 3.

Silvicultural systems for plantation mahogany in Africa: Influences of canopy-shade on tree growth and pest damage

E. Opuni-Frimponga,, D.F. Karnoskyb, A.J. Storerb, E.A. and J.R. Cobbinaha

a Forestry Research Institute of Ghana, Univ. Box 63 Kumasi, Ghana b School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Drive, Houghton, Michigan, 49931, USA

E-mail address: [email protected] and [email protected] (E. Opuni-Frimpong)

Abstract The African mahoganies, Khaya anthotheca and K. ivorensis have been exploited for over a century for their desirable physical and chemical timber properties. Demand has resulted in over exploitation, which could lead to these mahoganies becoming commercially extinct in the near future. Efforts to establish plantations to sustain supply are thwarted by the shoot borer Hypsipyla robusta Moore. In this paper we report on the growth of African mahoganies and Hypsipyla attack under 3 different forest canopy shade levels. Our hypothesis was that canopy-shade would morphologically reduce attractiveness of shaded trees and render them less vulnerable to attack by Hypsipyla, so that mahogany could grow to have the desirable straight single stems preferred for timber use. The results revealed that Hypsipyla attack was higher on K. anthotheca in the open canopy stand than closed canopy stand; 85%, 11% and 0% attack in the open, medium and deep shade stands, respectively. However, the growth rate under the forest canopy was very slow. We recorded mean tree height of 413.8 cm, 126.2 cm and 54.5 cm in the open, medium and deep shade experiments, respectively, for K. anthotheca. K. ivorensis showed similar trends. The severe growth limitations of partial or full shade, suggested that these are pioneer species requiring full sunlight. This research also points to the need for improved genetic tolerance in conjunction with alternative pest management procedures. Key words. Hypsipyla attack, African mahogany, canopy shade, leaf area index, seedlings growth

1.0 Introduction

African mahogany (Khaya species) has been harvested from the upper Guinean rain forest of Ghana for over a century (Atuahene, 2001). Mahogany wood represents a major contributor of timber-derived revenue of Ghana and neighboring West African countries (Brunck and Mallet, 1993; Dupuy, 1995; Atuahene, 2001). An increasing demand for mahogany has led to overexploitation resulting in severe reduction in the natural stands in West Africa (Dunish and Ruhmann, 2006; Alder, 1998; Atuahene, 2001; Hawthorne, 1993). Natural regeneration is generally unsuccessful after selective logging, as Khaya species are extremely light demanding, and survival is low relative to the rate of exploitation (Hawthorne, 1993; Alder, 1989), similar to results for Switenia macrophylla (Snook and Negreros-Castillo, 2004). Efforts to establish plantations to meet the increasing demand have persistently been hampered by the mahogany shoot borer, Hypsipyla robusta (Moore) (Lepidoptera: Pyralidae), in the native range of African mahogany (Beeson, 1919; Roberts, 1966; Grijpma, 1976; Newton et al., 1993; Ahuahene, 2001; Floyd and Hauxwell, 2001)

Mahogany shoot borer damage to young trees starts with the larvae boring into and feeding in the apical dominant shoots. This leads to dieback of succulent shoots causing sprouting of multiple lateral shoots and branches and reduces the commercial timber value of the tree (Wagner et al., 1991; Newtown et al., 1993; Mayhew and Newtown, 1998; Atuahene, 2001; Floyd and Hauxwell, 2001). Mahoganies require 4 – 5 years to produce a merchantable bole of 8-10 m (Grijpma, 1974) making attacks in the sapling stage very significant (Mahroof et al., 2002; Cornelius, 2000).

A number of studies of the principal mahogany pests, Hypsipyla shoot borer, have been conducted throughout the tropics. However, none of the pest control methods proposed has been able to reduce attacks to economically acceptable levels (Floyd and Hauxwell, 2001; Mahroof et al., 2002; Taveras et al., 2004). Some reviews have suggested planting mahogany under a nurse crop to reduce the Hypsipyla attack through shading (Entwistle, 1967; Newton et al., 1993; Mayhew and Newton, 1998; Hauxwell et al., 2001). Some benefit of planting mahogany in species mixtures is thought to accrue from shade arising in such silvicultural systems (Campbell, 1966; Lamb, 1966; Entwistle, 1967). The mechanisms by which shade per se may influence shoot borer attack are variable. Shade may reduce tree growth and alter shoot morphology, thereby reducing palatability to Hypsipyla. For example, Grijpma (1976) noted that stems grown under shade tend to be thinner and woodier, possibly reducing susceptibility to attack, as adults may prefer to oviposit on thick succulent shoots.

Shaded plants must compete for available light from above, which generally enhances apical dominance, if the shade is not too heavy. This may result in better form recovery after attack, specifically by encouraging more vertical growth rather than branching (Hauxwel et al., 2001) and reducing the number of sites available for attack (Entwistle, 1967; Grijpma, 1976).

Although shade may reduce damage by shoot borers, it can also have detrimental effects on mahogany growth. Khaya species are ‘light-demanding’ species and shade reduces their growth (Hawthorne, 1995). Thus, the use of shade in tree species mixtures must be carefully balanced to reduce shoot borer damage without excessively suppressing tree growth. Planting in shade may also be combined with planting mahogany in tree species mixtures to increase the likelihood of natural control by Hypsipyla predators and parasites. Therefore, carefully designed field trials are needed to assess the value of these different methods of utilizing shade to control shoot borers (Whitmore, 1976). Mahroof et al. (2002) planted mahogany in shade houses and looked at the effects of artificial shade on the mechanisms of host selection behavior of the shoot borer and the host suitability. Their results indicated that shading of mahogany seedlings reduces the incidence of shoot borer attack by influencing both oviposition and larval development. However, they observed that under high shade, larval tunnel length was longer than in low shade. Longer tunnel length will lead to longer stem dieback so that a longer time will be needed for the tree to become commercially useful (Opuni-Frimpong, 2000).

Despite the many suggestions in literature encouraging the use of shade in pest management, empirical data supporting shade effects on mahogany growth and susceptibility to Hypsipyla attack is very limited (Mahroof et al., 2005; Hauxwell et al., 2001; Newton et al., 1993). Our hypothesis was that canopy-shade would morphologically reduce attractiveness of shaded trees and render them less vulnerable to attack by Hypsipyla, so that mahogany could grow to have the desirable straight single stems preferred for timber use. To verify this hypothesis, we investigated the effects of tree canopy-shade on the growth of K. anthotheca and K. ivorensis and associated Hypsipyla attack in the moist forest of Ghana. Our view was to provide baseline data from the field to support integrated pest management programs being developed for this mahogany pest.

2.0 Applied methodology

2.1 Study location

The field experiments were established in the Bobiri forest reserve (6040’ 1019’W) in the moist semideciduous forest type of Ghana (Hall and Swaine, 1981). The forest canopy height ranges from 30-50 m with emergent trees up to 70 m tall. The Bobiri forest is about 35 km from Kumasi and has annual rain fall of between 1200 and 1750 mm. A dry season occurs from November through February, during which average rainfall is less than 100 mm. June and September are the wettest months of the year, with average precipitation of 210 mm and 190 mm, respectively. The average temperature of the hottest month (February) ranges 22.6 to 34.9oC and coolest month (August) ranges from 22 to 28oC. The forest is 54.6 km2 with 5.0 km2 set aside as research compartments and the remainder under a 40 year cycle selective logging. This forest type is found to be favorable for the growth of all the species of mahogany in West Africa (Hall and Swaine, 1981).

2.2 Experimental Design

Two species of African mahogany, K. ivorensis and K. anthotheca, were planted under 3 different forest canopy-shade levels. Three different canopy-shades (full sun, medium shade and deep shade) were created under the forest canopy by slightly modifying the methodology of Brokaw (1982) and Nichols et al. (1998). For the full sun we had 3 large plots of approximately 500 m2 for the trees to receive full irradiance. For the medium shade and the deep shade (closed canopy) we had 3 plots each of approximately 250 m2 a plot. Only brush was removed in the case of the deep shade but brush and saplings were removed to create the medium shade plots. In each plot, 60 seedlings each of K. ivorensis and K. anthotheca were planted out in 2001. The data reported here were collected in August 2003 and 2005.

2.3 Overstory Leaf Area Index

To assess the effect of the overstory canopy-shade on the growth of mahogany seedlings and shoot borer attack, we used hemispherical photography to calculate the leaf area index above the seedlings (Figure 1). Estimating canopy leaf area index and/or light availability on the basis of canopy architecture (overstory) has been widely used in ecophysiological research in tropical and temperate forests (Makana and Thomas, 2005; Feldhake et al., 2005; Beaudet and Messier, 2002; Chen et al., 1997; Rich et al., 1993). Because the technique estimates light availability based on canopy openness as the percentage of open sky, it can estimate light availability over a long period of time (Rich et al., 1993). A digital camera with a fisheye lens was positioned in the understorey to take hemispherical photographs of the canopy at all the 3 treatment shade levels. Three photos were taken in each replicate of each treatment and analyzed using WinSCANOPY version 2005A (Regent Instruments Inc., Quebec, Canada). The photos were analyzed to estimate the leaf area index of the overstorey canopy, the amount of irradiance reaching the forest floor and percentage of open sky.

(a)

(b)

(c)

Figure 1. Fisheye photographs representing mahogany plantations in our shading trials including: (a) deep shade (closed canopy; LAI ~‗ 5.4), (b) medium shade; LAI ~‗ 2.4, (c) full sun; LAI ~‗ 1.0.

2.4 Data Collection and Analysis

The seedlings were monitored for growth and Hypsipyla attack. Evaluation of phenological state and Hypsipyla attack on Khayas were carried out along with yearly assessments of growth and form traits. Annually we assessed phenology, tree height, and diameter at 10 cm above the ground, number of branches, height to first fork, and number of insect attacks. We determined relationships between variances and means and when necessary the data were transformed. The means per replicate of growth indices like tree height, diameter and height to first fork were log transformed. The percentage of attacked trees and survival were also arcsine square-root transformed before analyzing with GLM procedures in SAS. Data were analyzed using analysis of variance (ANOVA) of the GLM procedure in SAS (SAS Institute, 2004). For variables with significant treatments effects (P>0.05), means were separated using the Tukey studentized range test.

3.0 Presentation of the data

3.1 Microenvironment in the different shade levels.

The overstory canopy leaf area index (LAI) differed significantly (P<0.05) between the deep shade, medium shade and full sun experiments as LAI values assessed 5.39, 2.41 and 0.84 m2/m2for the deep shade (closed canopy), medium shade and full sun respectively (Table 1). The experimental seedlings growth decreased with increasing overhead forest canopy leaf area index (Figures 2 and 3). Hypsipyla attack was highest on both K. anthotheca and K. ivorensis in the open stands (Figure 4a). The survival of the 2 Khaya species increased with increasing availability of light (Figure 4b). The openness of each shade level and estimated available light is shown in Table 1. The open stand had mean openness of 54.12% and associated photosynthetic photon flux (PPFD) of 33.92 mol/m2/day whereas the closed canopy had openness of 10.70% and PPFD of 5.3 mol/m2/day.

Table 1. Light environments in the different shade levels used in our mahogny experiments: Percentage openness, forest canopy leaf area index (LAI, m2/m2), photosynthetic photon flux (PPFD, mol/m2/day) and their standard errors. All figures were estimated from hemispherical photos with WinSCANOPY 2001A (Regent Intruments, Inc., Quebec, Canada).

Shade level Openness LAI PPFD

Open Canopy (n = 12) 54.12 ± 2.85 0.84 ± 0.12 33.92 ± 1.39

Medium Shade (n = 9) 25.55 ± 1.05 2.41 ± 0.43 20.36 ± 0.88

Deep Shade (n = 9) 10.70 ± 0.47 5.39 ± 0.38 5.30 ± 0.26 400 7

350 (a) 6 24months 300 48moths LAI 5

(cm) 250 4

200 K. ivorensis ivorensis K. 3 150 Height of Height

2 Index Area Leaf Canopy-Shade 100

1 50

0 0 Deep Shade Medium Shade Open Shade Levels of Shade

500 6

450 (b) 5 400 24months 48months 350 LAI 4 (cm) 300

250 3 K. anthotheca 200

2

Height of 150 Canopy-ShadeLeaf Area Index

100 1

50

0 0 Deep Shade Midium Shade Open Shade Levels of Shade

Figure 2. Effect of three levels of overstory canopy-shade on height growth of (a) K. ivorensis and (b) K. anthotheca at 24 and 48 months in the moist semideciduous forest type in Ghana. 50 7

45 (b) 6

40 24months 48moths LAI 5 35 (mm) 30 4

25 K. ivorensis K. ivorensis 3 20 Diameter of Diameter 15 Canopy-shade Leaf IndexArea 2

10

1 5

0 0 Deep Shade Medium Shade Open Shade Level of Shade

70 6

(a) 60 24months 5 48months LAI 50 4 (mm)

40

3 K. anthotheca 30

2 Canopy-shade leave Area Index Area leave Canopy-shade Diameterof 20

1 10

0 0 Deep Shade Midium Shade Open Shade Level of Shade

Figure 3. Effect of three levels of overstory canopy-shade on diameter growth of (a) K. ivorensis and (b) K. anthotheca at 24 and 48 months in the moist semideciduous forest type in Ghana.

100 6

90 K. anthotheca 5 K. ivorensis 80 (((a) LAI (a) attacked 70 4

60 K. ivorensis

and and 50 3

40

K. anthotheca K. 2 Canopy-Shade Leaf Area Index Area Leaf Canopy-Shade 30

Percent of 20 1

10

0 0 Deep Shade Midium Shade Open Shade Levels of Shade

120 6

K. anthotheca (b) K. ivorensis LAI 100 5

80 4

60 3

40 2 Canopy-shade leaf area index Percent of K. anthotheca and K. ivorensis survival

20 1

0 0 Deep Shade Midium Shade Open Shade

Figure 4. Effect of three levels of over-story canopy-shade on (a) percent of trees attacked (b) survival of seedlings of Khaya anthotheca and K. ivorensis at 48 months in the moist semideciduous forest of Ghana.

3.2 Seedling Growth

The growth of the two African mahogany species, K. anthotheca and K. ivorensis, under the different shade levels were analyzed separately (Tables 2 and 3). There was significant (P<0.05) effect of the shade level on height, diameter and height to first fork growth of the seedlings of both species at 48 months in the field. The trends of diameter growth were not different from that of height growth. When we pooled the data together there were significant differences (P<0.05) between the growth of K. anthotheca and K. ivorensis for all parameters assessed (Table 4).

Table 2. Analysis of variance results for age 4 height, diameter, height to first fork, sprouted shoots, survival and percent of trees attacked by Hypsipyla for K. anthotheca at 3 levels of canopy-shade in a moist forest of Ghana. ______Parameters DF F-value P-value ______Height 2 73 <0.0001 Diameter 2 405.2 <0.0001 Height to first fork 2 44.45 0.0003 Number of Sprouted shoots 2 64.99 <0.0001 Percent survival 2 23.59 0.0014 Percent of trees attacked 2 957.5 <0.0001

Table 3. Analysis of variance results for age 4 height, diameter, height to first fork, sprouted shoots, survival and percent of trees attacked by Hypsipyla for K. ivorensis at 3 levels of canopy-shade in a moist forest of Ghana. ______Parameters DF F-value P-value ______Height 2 22.5 0.0016 Diameter 2 43.1 0.0003 Height to first fork 2 130.8 <0.0001 Number of Sprouted shoots 2 66.4 <0.0001 Percent survival 2 30.08 0.0007 Percent of trees attacked 2 145.2 <0.0001

Table 4. Analysis of variance results for age 4 height, diameter, height to first fork, sprouted shoots, survival and percent of trees attacked by Hypsipyla for differences between K. anthotheca and K. ivorensis at 3 levels of canopy-shade in a moist forest of Ghana. ______Parameters DF F-value P-value ______Height 1 35.1 <0.0001 Diameter 1 120.1 <0.0001 Height to first fork 1 31.5 <0.0001 Number of Sprouted shoots 1 53.0 <0.0001 Percent survival 1 28.8 <0.0001 Percent of trees attacked 1 201.4 <0.0001

Diameters at 48 months after field planting differed significantly (d.f. = 2, F = 74.16, P<0.0001) for K. ivorensis (Tables 3 and 6). Within the same time period K. anthotheca recorded significant differences (P<0.0001) in the open, medium and deep shade levels, respectively, for diameter growth (Figure 1b). The third growth parameter evaluated was the height to first branch resulting from Hypsipyla attack. At 48 months, 211.21 and 52.47 cm of mean height to first fork in the open and medium shade levels, respectively, for K. ivorensis (Table 6). There were no branches on the trees growing under the closed canopy experiment. The height to first fork recorded for K. anthotheca and K. ivorensis in the open and medium shade levels varied significantly (Tables 2 and 3), respectively.

Table 5. Means and standard errors for age 4 height, diameter, height to first fork, sprouted shoots, survival and percent of trees attacked by Hypsipyla for K. anthotheca at 3 levels of canopy-shade in a moist forest of Ghana. Mean values of a parameter with the same letter are not statistically different.

Parameters Mean values and mean standard error

Khaya anthotheca Open Medium Deep Shade Shade

Height 413.81a(36.5) 126.23b(11.2) 54.48c(4.9) Diameter 56.06a(3.5) 13.77b(0.9) 8.12c(0.6) Height to first fork 221.45a(22.5) 108.23b(11.1) 0*c Number of Sprouted shoots 2.50 a(0.1) 2.17a(0.2) 1.00b(0) Percent survival 99.35a(0.2) 83.54b(2.1) 59.94c(1.5) Percent of trees attacked 85.02a(0.2) 10.83b(0.2) 0.00c(0.0)

0* - under the deep shade there was no forking.

Table 6. Means and standard errors for age 4 heights, diameter, height to first fork, sprouted shoots, survival and percent Hypsipyla attack of K. ivorensis at 3 levels of canopy-shade in a moist forest of Ghana. Mean values of a parameter with the same letter are not statistically different.

Parameters Means values and standard errors

Khaya ivorensis Open Medium Deep Shade Shade

Height (cm) 318.47a(50.5) 74.65b(12.0) 25.95b(4.3) Diameter 44.19a(0.3) 10.40b(0.9) 5.10b(0.1) Height to first fork 211.21a(52.1) 52.47b(13.1) 0* Number of Sprouted shoots 2.18a(0.1) 2.13a(0.1) 1.00b(0.0) Percent survival 92.74a(1.9) 76.11a(0.4) 33.33b(0.4) Percent of trees attacked 73.27a(1.8) 16.25b(1.9) 0.00c(0.0)

0* - under the deep shade there was no forking.

3.3 Hypsipyla attacks and Sprouting of Shoots

Variation in the Hypsipyla attacks in the shade levels in K. ivorensis and K. anthotheca experiments were highly significant (P<0.001) when data of the two species were analyzed separately by GLM procedures in SAS (Tables 2 and 3). Percentage of K. anthotheca attacked recorded at the 48 months assessment was 85%, 11% and 0.0% in the open, medium and deep shade experiments, respectively, and differed significantly (Table 2). Similar trend of attacked levels were observed on the K. ivorensis trees in the experiments. Within the three levels of shade Hypsipyla attack observed there were highly significant differences between the open, medium and deep shade levels (Tables 2 and 3).

Sprouting of multiple shoots in response to Hypsipyla attack was also assessed at the 48 months experimental evaluations. The analysis of variance results revealed highly significant differences between the different shade levels for both K. anthotheca and K. ivorensis (Tables 1 and 2). When the mean data of each treatment were compared with Tukey’s studentized range test, there were no differences between the mean value of shoots sprouted in the open and medium shade experiments. The sprouted shoots recorded within the medium shade level averaged 2.13 per tree in K. ivorensis while 2.18 sprouts per tree were reported in the attacked trees in the open shade experiment. The K. ivorensis under the deep shade recorded no Hypsipyla attacks and, therefore, no forked shoots. When the mean values of sprouted shoots of K. anthotheca were compared with Tukey’s studentized range test again there were no differences between the sprouted shoots per attacked tree in the open (2.50 shoots per tree) and medium (2.17 shoots per tree) shade experiments. Like the K. ivorensis in the deep shade, K. anthotheca was not attacked and we did not record any branching in this stand.

3.3 Seedling Survival

The African mahoganies, K. anthotheca and K. ivorensis, survived best in the open, followed by medium shade, and they had relatively low survival in the deep shade (Figure 4). The overall survival of K. ivorensis was 67.40% while that of K. anthotheca was 80.76%. Tukey’s studentized range test revealed significant differences (P<0.05) between survival of K. anthotheca and K. ivorensis (Tables 2 and 3).

4.0 Analysis and interpretation of data and results

Our results demonstrate that mahogany growth varied in response to the overstory canopy shade level and the associated photosynthetic photon flux (PPDF). K. anthotheca seedlings grew approximately 3 to 8 times taller in the medium or open (full sun) than in deep shade (Table 1). The diameter growth registered similar trends. These growth trends were in agreement with previous studies of light-demanding tropical tree species seedling performance under different irradiances. The growth of most light-demanding tropical tree species increases with increasing availability of light (Makana and Thomas, 2005; Snook and Negreros-Castillo, 2004; Agyeman et al., 1999; Nichols et al., 1998; Veenendaal et al., 1996). Under the medium shade not only were the tree height growths lower relative to the open experiment but the stems were also slender as the trees used the limited resources to grow tall to capture light (Brown, 1996) at the expense of radial growth. Grijpma (1976) reported that stems grown under shade were often thinner and woodier, which he suggested could be a mechanism for the tree to reduce susceptibility to attack since adult Hypsipyla may prefer to lay eggs on thick succulent shoots.

The magnitude of the differences in K. ivorensis performance with respect to the growth indices assessed in the different shade levels was even greater. Tree heights for open grown trees and medium shade trees were more than 10 and 4 times taller than the deep shaded trees, respectively (Table 6). Diameter growth also followed similar trends demonstrated in the height growth. The observations made in our study agree with the classification of the Khaya species as light demanding species (Hawthorne, 1993). The growth performance exhibited in the different shade experiments compared favorably to previous published data (Makana and Thomas, 2005; Snook and Negreros-Castillo, 2004; Grogan et al., 2003; Negreros-Castillo et al., 2003). The differences in growth between K. anthotheca and K. ivorensis under the different shade levels may be attributed to their inherent genetic make up (Hawthorne, 1993). K. anthotheca is widespread throughout all the dry and moist forest types in Ghana with faster growth rate, but K. ivorensis is restricted only to the moist forest types with relative slow growth rate at the early stages (Hall and Swaine, 1981).

The 99% survival of K. anthotheca in the open canopy compare to the 60% in the deep shade experiment confirms the significant influence that the overstory canopy-shade has on seedling performance under the forest canopy (Table 1, Figure 4b). The impact of shade on the seedling survival was more apparent in the K. ivorensis experiment. Over 65 % mortality recorded in the deep shade compared to less than 8% mortality in the open canopy experiment of the K. ivorensis seedlings after 48 months in the field attest to the fact that the species is light demanding (Hawthorne, 1995). In the medium shade experiment when the overstory canopy leaf area index was reduced and the associated light available to the seedlings increased from 5.30 mol/m2/day (deep shade) to 20.36 mol/m2/day, the survival rate increased sharply from 33% to 76%. The survival rates we recorded were consistent with the higher survival rate of seedlings in forest gaps than in the forest understory reported in comparable studies (Nichols et al., 1998; Snook and Negreros-Castillo, 2004; Mankana and Thomas, 2005; Balderrama and Chazdon, 2005). The relative position of each seedlings and its associated micro site affected survival of seedlings under canopy. Lateral penetration of light from gaps could support survival of some seedlings (Brown, 1996).

4.2 Hypsipyla attack Shoot borer attack is considered the single most important factor hindering the successful mahogany plantation development in the native range of African mahogany (Floyd and Hauxwell, 2001; Mayhew and Newton, 1998). The pattern of shoot borer attack followed the expected trend. The attack was more severe in the open canopy and only spread to the medium canopy with no attack recorded in the deep shade experiments (Figure 4a). Mahroof et al. (2002) suggested that the amount of light available to mahogany seedlings could influence their susceptibility to shoot borer attack since Hypsipyla oviposited a large number of eggs on mahogany seedlings in relatively high light environment in their study. Although our results corroborate this observation, the low growth rate and survival under the deep shade which was free from Hypsipyla attack could be more detrimental to commercializing plantations than the pest attack.

Trees grown in the open responded to attack with sprouting of more shoots compared to those in medium shade. This might have been due to competition for light in the medium shade enhancing apical dominance, resulting in a better form recovery after attack by encouraging more vertical growth than epicomic branching (Hauxwell et al., 2001). Another possible mechanism under shade could be that natural pruning of thinner and weaker branches encouraged apical dominance. K. anthotheca tree height to first fork relative to total tree height was 53% in the open canopy experiment compared to 86% recorded in the medium shade. Despite the large number of attacks in the open canopy stand and the associated branching of the trees on the open stand, the height to first fork (commercial height) was 2 times higher in the open than the medium shade. This might be due to better tree growth in the full sun and natural pruning of lower branches as the tree ages.

5.0 Conclusions

Our results suggest that overhead canopy shade reduces the attack levels in mahogany saplings. However, determining the precise level of light required to reduce attack to tolerable level without compromising commercial growth rate need to be carefully determined for each species. The efficient searching ability of Hypsipyla will make it prudent to plant seedlings that are relatively tolerant to Hypsipyla in shade levels that are not detrimental to growth. The data presented here supports the suggestion that enrichment planting of mahogany seedlings under the tropical closed forest canopy may take too long a time to restore and support sustainable production of critically valuable timber like mahogany (Snook and Negreros-Castillo, 2004).

6.0 Recommendations

Further studies is needed to determine the precise levels of light required to reduce Hypsipyla robusta attacks to tolerable levels without compromising commercial growth rates for each of the species. Silvicultural systems with shade manipulation should be reexamined with lower densities of the mahoganies in various shade levels in different ecological regions to optimize these tools for integrated pest management of Hypsipyla shoot borer. Biological control agents for Hypsipyla should be evaluated with all silvicultural treatments to document their roles in the different systems. Especially the association between ants, mahogany trees and Hypsipyla shoot borer needs to be explored as field observations and literature point to a possible predation relationship between ants and Hypsipyla shoot borer. The use of female sex pheromones in managing pest must be evaluated with other silvicultural systems for integrated management of the Hypsipyla shoot borer.

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Journal of Ecology 87, 772-783. Lamb, F.B., 1966. Mahogany of tropical America: Its ecology and management. The University of Michigan Press, Ann Arbor, Michigan, USA. 220 pp. Makana, J-R., Thomas, S.C., 2005. Effects of light gaps and litter removal on the seedling performance of six African timber species. BIOTROPICA 37, 227– 237. Mahroof, R.M., Hauxwell, C., Edirisinghe, J.P., Watt, A.D., Newtom, A.C., 2002. Effects of artificial shade on attack by the mahogany shot borer, Hypsipyla robusta (Moore). Agriculture and Forest Entomology 4, 283-292. Mayhew J.E., Newton A.C., 1998. The silviculture of mahogany. CABI Publishing Great Britain.. Negreros-Castillo, P., Snook, L.K. Mize, C.W., 2003. Regenerating mahogany (Swietenia macrophylla) from seed in Quintana Roo: the effect of sowing method and clearing treatment. For. Ecol. Manage. 183, 351-362. Newton, A.C., Baker, P., Ramnarine, S., Mesen, J. F., Leaky, R.R.B., 1993. The mahogany shoot-borer, prospects for control. For. Ecol. Manage. 57, 301-328. Nichols, J.D., Wagner, M.R., Agyeman, V.K. Bosu, P., Cobbinah, J.R., 1998. Influence of artificial gaps in tropical forest on survival, growth, and phytolyma lata atta on Milicia excelsa. For. Ecol. Manage. 110, 353-362. Opuni-Frimpong, E., 2000. Damage to growth and survival of native Meliaceae (African mahogany) by Hypsipyla robusta Moore (Lepidoptera:Pyralidae). M.Phil. thesis submitted to Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. 100 pp. Ramos, G., Grace, J., 1990. The effects of shade on gas exchange of seedlings of four tropical trees. Functional Ecology 4, 667-677. Rich, P.M., Clark, D.B., Clark, D.A., Oberbaur, S.F., 1993. Long-term study of solar radiation regimes in a tropical wet forest using quantum sensors and hemispherical photography. Agriculture and Forest Meteorology 65, 107-127. Roberts, H., 1966. A survey of the important shoot, stem, wood, flower and fruit boring insects of the Meliaceae in Nigeria. Nigerian Forest Information Bulletin (New Series), pp. 15-38. Snook, L.K., 1996. Catastrophic disturbance, logging and the ecology of mahogany (Swietenia macrophylla King) Grounds for listing a major timber species in CITES Bot. J. Linn. Soc. 122, 35-46. Snook, L. K. and Negreros-Castillo, P., 2004. Regenerating mahogany (Sweitenia macrophylla King) on clearings in Mexico’s Maya forest: the effects of clearing method and clearing on the seedling survival and growth. For. Ecol. Manage.189, 143-160. Taveras, R., Hilje, L., Hanson, P., Mexzon, R., Carballo, M., and Navarros, C., 2004. Population trends and damage patterns of Hypsypyla grandella (Lepidoptera: Pyralidae) in a mahogany stand, in Turrialba, Costa Rica. Agriculture and Forest Entomology 6, 89-98. Veenendaal, E.M., Swaine, M.D., Lecha, R.T., Walsh, M.F., Abebrese, I.K., Owusu-Afriyie, K., 1996. Responses of West African Forest Tree Seedlings to Irradiance and Soil Fertility. Functional Ecology 10, 501-511. Wagner, M. R., Atuahene, S.K.N., Cobbinah, J. R., 1991. Forest Entomology in West Africa Forest Insects of Ghana, Kluwer Academic Publishers, Dordrecht, Netherlands. Whitemore, J. L., 1976. Studies on the shoot borer Hypsipyla grandella (Zeller) Lep. Pyralidae. Vol. II. IICA Miscellaneous publications No. 101, CATIE, Turialba, Costa Rica.

Major Research 4.

Silvicultural systems for plantation mahogany in Africa: Effect of mixed species stands on growth and Hypsipyla attack of African mahogany (Khaya anthotheca and K. ivorensis)

E. Opuni-Frimpong1, D.F. Karnosky2, A.J. Storer2, W.K. Asare2 and J.R. Cobbinah1

1 Forestry Research Institute of Ghana, University Box 63, Kumasi, Ghana. 2 School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Drive, Houghton MI 49931, USA

E-mail address: [email protected] and [email protected] (E. Opuni-Frimpong)

Abstract Attack caused by Hypsipyla robusta (Moore) shoot borer of mahogany trees leads to death or disfigurement of the young terminal shoots which results in considerable growth retardation, formation of numerous secondary shoots or, in worst cases, death. Young trees are particularly affected by shoot borer because of destruction of the rather fragile juvenile apical meristems and stems. Interplanting mahogany trees with other trees or shrubs is considered as a possible management tool for minimizing the effect of Hypsipyla infestation in mahogany plantations. Hypsipyla, like most oligophagous insects, primarily locate their host trees by olfaction. It is therefore believed that in mixed stands, chemical signals given off by non- meliaceae species in or around a stand may act as repellents; thus, preventing the pest from locating the mahogany trees. This study was established to examine the effects of mixed plantations, companion planting and fertilizer treatments on the impact of Hypsipyla attacks on two African mahogany species, Khaya anthotheca (Welw.) and K. ivorensis (Chev.). Trees in treatments were monitored for tree growth (height & diameter), Hypsipyla attack, tree branching in response to attack, and length of dieback of attacked stems. After 36 months in the field, there were no significant differences in height and diameter growth between treatments for either K. anthotheca or K. ivorensis. Shoot borer attacks were significantly greater in fertilizer treatments than mixed planting in both K. anthotheca and K. ivorensis experiments. Trees in the fertilizer treatments responded to attacks with more branching compared to trees in other treatments. Mixed stands do not prevent Hypsipyla attack but they appear to improve the ability of mahogany trees to tolerate Hypsipyla attack. Key words: African mahogany, Hypsipyla attack, mixed species, fertilizer, branching level

1.0 Introduction

Attack caused by Hypsipyla shoot borer (Hypsipyla robusta Moore) to mahogany trees leads to death of the young terminal shoots which results in considerable growth retardation and formation of numerous secondary shoots. This condition encourages the production of poorly formed trees unsuitable for timber. Although attacks do not normally cause death, repeated attacks can kill trees (Grijpma, 1976). Trees may be attacked in the nursery stage and attacks may continue throughout the plant’s life in the field (Grijpma, 1976; Griffiths et al., 2001). Young trees are particularly affected by shoot borers because of destruction of the fragile juvenile apical meristem and stems. Attacks up to the pole stage are most critical from a silvicultural point of view (Hauxwell et al., 2001; Griffiths et al., 2001). The complete life cycle of Hypsipyla takes between 29 and 55 days depending on climate and host suscetibility (Atuahene and Souto, 1983; Couilard and Guiol, 1980; Opuni-Frimpong, 2000). There are often six to nine overlapping generations in the tropical forest in a year (Wagner et al., 1991).

Gains from the use of genetically improved mahogany trees can only be fully realized if appropriate silvicultural management systems are employed to minimize the impact of Hypsipyla. Among other management systems, this might involve the use of mixed species plantations and/or application of fertilizer. Several studies have shown an increase in tip moth or shoot borer damage associated with reduction in competing vegetation of other species (Snook and Negreros-Castillo, 2004; Nowak et al., 2003; Hauxwell et al., 2001; Ross et al., 1990). Species mixtures may alter plant suitability for growth of the insect, screen host plants from adult insects, or increase levels of natural enemies (Gibson and Jones, 1977; Watt, 1992).

The use of mixed plantings of Meliaceae with other timber species or agricultural crops has also been recommended for West Africa and elsewhere (Beeson, 1919; Entwistle, 1967; Brunck and Mallett, 1993; Hauxwell et al., 2001; Opuni-Frimpong et al., 2005). As early as 1910, successful reduction in shoot borer damage in Entandrophragma plantations in Togo was obtained using teak as a nurse crop (McLeod, 1915). The Forestry Department of Nigeria has employed tree species mixtures in an attempt to control shoot borers (Roberts, 1966). When the nurse crop (usually Nauclea diderichii or Gmelina arborea) and the mahogany were planted in separate rows, there was little evidence of control, but when the nurse and mahogany trees were planted in a mixture in the same rows, some degree of control was obtained (Roberts, 1966). Similar results have been shown for mixed line plantings in Côte d’lvoire (Brunck and Mallet., 1993). In addition, variable-age species mixtures and mixtures with some types of trees (e.g Leucena) have been shown to give some degree of Hypsipyla control (Brunck and Mallet, 1993; Dupuy, 1995).

Interplanting mahogany trees with insect repellent trees or shrubs is considered one of mixtures that could help reduce the effect of Hypsipyla on mahogany plantations. Hypsipyla, like most oligophagous insects, primarily locate their host trees by olfaction (Grijpma, 1976). It is, therefore, believed that in mixed stands, chemical signals given off by non-Meliaceae species in or around a stand may act as repellents; thus, preventing the pest from locating the mahogany tree (Hauxwell et al., 2001). There are over 70 native Ghanaian plant species which have been observed to have insecticidal properties and Neem (Azadirachta indica) is one of the most promising (Cobbinah et al., 1999; Tuani et al., 1994).

The effect of fertilization on mahogany growth and response to Hypsipyla has been variable thus far. In some cases herbivorous insects, including mahogany shoot borer, have performed better on fast growing seedlings (Akanbi, 1986; Mahroof et al., 2002; Nowak et al., 2003). Brunk and Mallet (1993) showed that fertilizer application increases the growth of Khaya species but it was also associated with higher Hypsipyla attack. Hauxwell et al., (2001) predicted that although incidence of Hypsipyla may increase, fertile soil could promote vigorous cambial growth and better recovery after attack. Kyto et al., (1999) also showed that fertilization can be used to accelerate tree recovery from defoliation without affecting the pest resistance of a tree. The objectives of this study were to examine the effects of mixed species plantings, fertilizer treatments, and companion plantings on the growth of mahogany trees and on the level of shoot borer Hypsipyla damage for two important African mahoganies, Khaya anthotheca Welw. and K. ivorensis Chev.

2.0 Applied methodology

2.1 Study Site

This study was located in the moist semideciduous forest type (Hall and Swiane, 1981) of Ghana’s Upper Guinean tropical forest. This forest type is favorable for the growth of all the native West African mahogany species. The annual precipitation ranges between 1200 and 1750 mm per annum in this region and there is a dry season between December and March with rainfall of less than 100 mm per month. All experiments were established at the Forestry Research Institute of Ghana (FORIG), Mesewam nursery and research center near Kumasi.

We established seedlings of Khaya anthotheca, K. ivorensis, Albizia adianthifolia (Albizia), Cedrela odorata (Cedrela), Terminalia ivorensis (Emire) and Azadirachta indica (Neem) in the FORIG Mesewam nursery in polyethylene bags using topsoil as the growing media. Seeds of the African mahoganies were collected from superior trees growing in the moist semideciduous forest. Healthy mahogany seedlings, free of insect damage and without branches were selected for field planting when they were about 35 cm tall. The seedlings of the mixed species were between 40 and 50 cm tall at the time of planting.

2.2 Experimental Design

We established a set of experiments with: (1) pure mahogany species and (2) mixed species trees for both mahogany species, (3) added fertilizer at various amounts and (4) line or companion plantings (Table1). For the mixed species experiments, treatments were 75% Khaya x 25% mixed spp; 50% Khaya x 50% mixed spp; 25% Khaya x 75% mixed spp and 100% Khaya. The species used in the mixed experiments with the Khaya species were Albizia adianthifolia, Cedrela odorata, Terminalia ivorensis. Each replicate plot had 60 seedlings of Khaya and the mixed species. The seedlings were planted randomly in each plot and the mixed species were represented equally in each plot. Examples for 50% Khaya x 50% mixed spp. were represented by 30 seedlings of Khaya and 30 seedlings of mixed spp which consist of 10 Albizia, 10 Cedrela and 10 Terminalia seedlings planted randomly in a mixture.

Table 1. Treatments in the field Experiments Treament levels ______Khaya Spp Cedrela Albizia Terminalia Neem 1 Pure Khaya 30 trees 10 trees 10 trees 10 trees 0 2 Pure Khaya 60 trees fertilizer at 60 g, 80 g and 120 g/tree 3 Pure Khaya 30 trees 0 30 trees or 30 trees

Our second experiments consisted of fertilizer treatments at different rates for both K. ivorensis and K. anthotheca. We applied NPK fertilizer of 15-15-15% at rates of 60 g, 80 g and 120 g to each seedling (Hunter and Schultz, 1995) of 20 seedlings per plot, 2 years after planting in the field. We applied the fertilizer by digging a 1-2 cm deep at 40 cm radius around each seedling, spreading the fertilizer in the trench and covering the trench. There was a control experiment of pure K. anthotheca and K. ivorensis without fertilizer.

For the line versus companion planting, we interplanted Khaya species with Azadirachta indica or Albizia adianthifolia. Azadirachta indica was selected as an insect repellent (Hauxwell et al., 2001; Cobbinah et al., 1999; Tuani et al., 1994) species to shield mahoganies from Hypsipyla attack. Albizia adianthifolia, on the other hand, was selected as a fast-growing, nitrogen fixing plant which may improve soil fertility and also provide shade (Mahroof et al., 2002) to reduce impact of Hypsipyla attack. Sixty seedlings were represented in each experiment made up of 30 seedlings of Khaya and 30 seedlings of Neem or Albizia. Thus, the planting rate was 50% Khaya x 50% Neem or Albizia. All experiments were replicated tree times.

2.3 Data Collection and Analysis

Monitoring and evaluation of the phenological state of all experimental trees and Hypsipyla attack on Khaya species were carried out with assessment of growth and form traits. Parameters assessed were: tree height, diameter, clear bole as height to first fork, (Newton et al., 1999); commercial height (Cornelius and Watt, 2003); crown height (Helms, 1998), number of branches and number of insect attacks. We analyzed tree growth data using analysis of variance (ANOVA) of the GLM procedure in SAS (SAS Institute, 2004) and means were separated using the Tukey’s studentized range test  = 0.05. Replicate means of Hypsipyla attacks per tree, branches in response to attack, length of dieback and dead shoots were arcsine square-root transformed and subjected to analysis of variance (ANOVA) using GLM procedures in SAS. Where there were significant differences between treatment means, they were compared by the Tukey’s studentized ranged test, α = 0.05.

3.0 Presentation of the data

3.1 Growth of Mahogany

After 3 years from planting, Khaya anthotheca heights ranged from 161 to 248 cm in the 25% K. anthotheca mixed with 75% of other species to K. anthotheca treated with 120 g fertilizer, respectively (Figure 1a). The diameters ranged from 37 to 54 mm in the 25% K. anthotheca mixed with 75% of other species to 50% K. anthotheca interplant with 50% Albizia, respectively (Figure 1b). Analysis of variance showed no significant differences between the treatments for both height and diameter growth of K. anthotheca. The height growth of K. ivorensis within the same time period was similar to that of K. anthotheca and ranged from 160 to 244 cm in the 50% K. ivorensis mixed with 50% of other species to the pure K. ivorensis (control), respectively (Figure 2a). K. ivorensis diameters varied from 33 to 52 mm in the 25% K. ivorensis mixed with 75% of other species to K. ivorensis treated with 120 g fertilizer, respectively (Figure 2b).

The clear bole also varied between the treatments, though differences were not statistically significant when analyzed with GLM procedures in SAS. The clear bole of K. anthotheca ranged from 114 cm in the 25% K. anthotheca mixed with 75% of other species to 154 cm in the 50% K. anthotheca interplant with Neem as a companion planting (Figure 3b). The K. ivorensis clear bole varied from 122 cm in the K. ivorensis plots treated with 120 g fertilizer to 171 cm in the 50% K. ivorensis mixed with 50% of other species (Figure 3a).

350

300 a

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150 Khaya anthothecaKhaya

100 Height of

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0 Ka-Pure Ka75-Mixed Ka50-Mixed Ka25-Mixed Ka120gF Ka80gF Ka60gF Ka-Neem Ka-Albizia 70

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0 Ka-Pure Ka75-Mixed Ka50-Mixed Ka25-Mixed Ka120gF Ka80gF Ka60gF Ka-Neem Ka-Albizia 120

100 c

80 trees with Shoot borer present) 60

40 K. anthotheca

20 attack (% (% attack

0 Hypsipyla Ka-Pure Ka75- Ka50- Ka25- Ka120gF Ka80gF Ka60gF Ka-Neem Ka-Albizia Mixed Mixed Mixed Figure 1. The effects of silvicultural treatments (monoculture, mixed culture, fertilizer) on height (a) and diameter (b) growth of Khaya anthotheca; and percentage of trees attacked by mahogany shoot borer Hypsipyla(c) for trees grown near Kumasi, Ghana. Mean ± SE. Ka-pure = Khaya anthotheca pure stand, Ka75-Mixed = 75% K. anthotheca mixed with 25% of other species. Ka50-Mixed = 50% K. anthotheca mixed with 25% of other species. Ka25-Mixed = 25% K. anthotheca mixed with 75% of other species. Ka120gF = K. anthotheca plot with 120g fertilizer per tree. K80gF = K. anthotheca plot with 80g fertilizer per tree. Ka60 = K. anthotheca plot with 60g fertilizer per tree. Ka- Neem = K. anthotheca and neem companion plot. Ka-Albizia = K. anthotheca and Albizia companion plot.

300

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0 Ki-Pure Ki75-Mixed Ki50-Mixed Ki25-Mixed Ki120gF Ki80gF Ki60gF Ki-Neem Ki-Albizia 120 c 100

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K. ivorensis 40

20 attack (% of of (% attack

Hypsipyla 0 Ki-Pure Ki75-Mixed Ki50-Mixed Ki25-Mixed Ki120gF Ki80gF Ki60gF Ki-Neem Ki-Albizia Figure 2. The effects of silvicultural treatments (monoculture, mixed culture, fertilizer) on height (a) and diameter (b) growth of Khaya ivorensis and percentage of trees attacked by mahogany shoot borer Hypsipyla (c) for trees grown near Kumasi, Ghana. Mean ± SE. Ki-pure = Khaya ivorensis pure stand, Ki75-Mixed = 75% K. ivorensis mixed with 25% of other species. Ki50-Mixed = 50% K. ivorensis mixed with 25% of other species. Ki25-Mixed = 25% K. ivorensis mixed with 75% of other species. Ki120gF = K. ivorensis plot with 120g fertilizer per tree. K80gF = K. ivorensis plot with 80g fertilizer per tree. Ka60 = K. ivorensis plot with 60g fertilizer per tree. Ka-Neem = K. ivorensis and neem companion plot. Ka-Albizia = K. ivorensis and Albizia companion plot.

250 a

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100 Clear bole height of of height bole Clear 50

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100 Khaya anthotheca 80

60

40

Clear Boleheight of 20

0 Ka-Pure Ka75- Ka50- Ka25- Ka120gF Ka80gF Ka60gF Ka-Neem Ka-Albizia Mixed Mixed Mixed

Figure 3. The effects of silvicultural treatments (monoculture, mixed culture, fertilizer) on clear bole height of (a) Khaya ivorensis (b) K. anthotheca after 36 months in the field near Kumasi, Ghana. Mean ± SE.

3.2Hypsipyla Damage

The percentages of trees attacked were higher in the fertilizer treated plots in both the K. anthotheca and K. ivorensis experiments (Figure 1C and 2C). The pattern of Hypsipyla attack differed significantly between the treatments for both K anthotheca (P = 0.0004, d.F. = 8, F = 8.22) and K. ivorensis (P = 0.0002, d.f. = 8, F = 8.95). The number of attacks varied from 1.5 per tree in the 25% K. anthotheca mixed with 75% of other species to 7.65 per tree for the K. anthotheca stand treated with 80 g fertilizer (Table 2). K. anthotheca were attacked in all treatments with the least attacks in the mixed planting and the most attacks in the fertilizer- treated plots. Attacks in the K. ivorensis plots were lower than in K. anthotheca trials. Attacks ranged from 0 per tree in the 25% K. ivorensis mixed plots to 3.8 attacks per tree in the K. ivorensis plots treated with 120 g fertilizer (Table 3). It was only the 25% K. ivorensis mixed with other species for which there were no attacks after 36 months in the field.

Table 2. The effect of silvicultural treatment (monoculture, mixed planting and fertilizer) on mahogany shoot borer attack, total sprouted shoots, dead shoots and length of dieback of Khaya anthotheca. Means of a response to treatment with the same letters are not statistically significant. Numbers in parenthesis are standard errors. Response ______Treatment Attacks/tree Total shoots Dead shoots/tree Length of

dieback (cm)

Ka 80g fertilizer 7.65a (0.4) 8.30a (0.4) 7.60a (0.3) 31.61 (3.0) Ka 120g fertilizer 6.63a (1.1) 7.87ab (2.4) 6.63ab (1.8) 21.96 (4.3) Ka 60g fertilizer 7.01ab (2.0) 7.67abc (2.5) 6.41ab (2.0) 13.75 (0.2) Ka50% +50%Albizia 6.47abc (0.8) 6.81abc (0.9) 6.72ab (0.7) 15.50 (3.1) Ka 50% + 50%Neem 3.52abcd (0.6) 4.46abc (0.4) 4.23ab (1.2) 18.96 (4.2) Ka Pure 2.19bcd (0.3) 3.53abc (0.2) 1.75ab (0.8) 15.42 (0.6) Ka75% + 25%mixed 1.89cd (0.4) 2.91abc (0.4) 1.58ab (0.6) 43.67 (28.3) Ka50% + 50%mixed 1.81d (0.3) 2.58 bc (0.3) 1.30ab (0.3) 19.25 (4.25) Ka25% + 75%mixed 1.50d (0.5) 2.36c (0.4) 2.00b (0.5) 16.00 (0.5) Main effects* 0.0004 0.0012 0.009 0.435

*P-values of main effects of ANOVA using GLM procedures in SAS

Table 3. The effect of silvicultural treatment (monoculture, mixed planting and fertilizer) on mahogany shoot borer attack, total sprouted shoots, dead shoots and length of dieback of Khaya ivorensis. Means of a response to treatment with the same letters are not statistically significant. Numbers in parenthesis are standard errors

Response ______Treatment Attacks/tree Total shoots Dead shoots/tree Length of dieback (cm)

Ki 120g Fertilizer 3.81a (0.1) 4.94a (0.2) 3.81 (0.5) 11.15a (2.5) Ki pure 3.45a (0.2) 4.22ab (0.3) 3.44 (0.1) 15.06a (4.7) Ki + Neem 2.55ab (0.5) 2.85abc (0.4) 2.50 (0.5) 9.61a (1.0 Ki 80g fertilizer 2.39ab (0.4) 2.78abc (0.7) 2.00 (0.3) 11.10a (3.3) Ki + Albizia 2.22ab (0.5) 2.84abc (0.8) 1.89 (0.2) 10.73a (4.4) Ki75% +25%mixed 1.68ab (0.7) 2.64abc (0.4) 2.35 (0.7) 11.14a (0.6) Ki 60g fertilizer 1.63ab (0.1) 2.60abc (0.1) 1.50 (0.5) 5.50ab (0.5) Ki50% +50%mixed 1.26ab (0.3) 1.58bc (0.6) 1.35 (0.2) 5.44ab (2.4) Ki25% +75%mixed 0.00b (0.0) 1.00c (0.0) 0.0 0.00b (0.0) Main effects* 0.0002 0.0075 0.138 0.0036

*P-values of main effects of ANOVA using GLM procedures in SAS

Mahoganies generally respond to Hypsipyla attack with sprouting of multiple shoots. The response of the K. anthotheca to sprouting followed similar trends to the Hypsipyla attacks in this species. The higher the attacks per tree for a treatment resulted in larger numbers of shoots sprouted (Table 2). Mahoganies in the 25% K. anthotheca mixed species plots had the lowest number of branches, 2.4 per tree, while the K. anthotheca treated with 80 g of NPK fertilizer recorded the highest number of branches, 8.3 per tree (Table1). For K. ivorensis, trees in 25% K. ivorensis mixed with other species had no branches at the end of the 36 months compared to 4.9 branches per tree recorded in the K. ivorensis plots treated with 120 g fertilizer. Branching in response to Hypsipyla attack differed significantly (P< 0.05) between treatments for both K. anthotheca and K. ivorensis (Tables 2 and 3).

Dead shoots resulting from attacks increased with increasing attacks per tree as expected (Tables 2 and 3). The number of dead shoots per tree differed significantly for both K. anthotheca (P = 0.009, d.f. = 8, F = 4.87) and K. ivorensis (P = 0.007, d.f. =8, F = 4.47) treatments. Apart from branching, dieback of the apical meristem when Hypsipyla attacks mahogany is a major setback to the continuous growth of the trees in the plantations. The length of dieback recorded for the K. anthotheca ranged from 13.75 cm in the 60 g fertilizer treatment experiment to 43.67 cm in the 75% of K. anthotheca mixed with other species (Table 2). Analysis of variance revealed no significant differences between the K. anthotheca treatments but there were significant differences between K. ivorensis treatments. In the case of K. ivorensis, the length of dieback varied from 0.0 to 15.06 cm for the 25% of K. ivorensis mixed with other species to the pure stand (control), respectively.

3.3 Growth of Companion and Mixed Species

All species mixed with the K. ivorensis and K. anthotheca outgrew the mahoganies as shown in Figure 4. Cedrela, which is an exotic mahogany from Central America and free from Hypsipyla robusta attack in Ghana, had the largest diameter, over twice that of K. ivorensis.

120

100

80

60 Diameter of trees 40

20

0 K. ivorensis K.anthotheca Azadirachta Terminalia Albizia Cedrela

Figure 4. Mean diameter growth of all species used in the mixed species and companion experiments at 36 months in the field near Kumasi, Ghana.

4.0 Analysis and interpretation of the data and results

There is a general belief that mahoganies suffer more attacks when planted in monoculture plantations compared to mixed plantations (Hauxwell et al., 2001, Floyd and Hauxwell C., 2001; Newton et al., 1993) but very limited data is available to support this hypothesis (Brunck and Mallet 1993; Speight and Wylie 2001; Mayhew and Newton, 1998). Our results demonstrated that Hypsipyla attack on Khaya anthotheca in monoculture was not significantly different from that of the three different densities of mixed-species planting. However, the lowest level of mixture of 25% K. anthotheca and 75% of 3 other mixed species recorded the lowest Hypsipyla attack. This suggests that a lower portion of K. anthotheca in mixed planting with other species may lower the attack rate as observed in Milicia species (Nichols et al., 1999). Wazihullah et al. (1996) observed less stem borer attack on Sonneratia apetala (Keora) in mixed-species plantations compared to monoculture plantations of Keora in Bangladesh. In our study, K. anthotheca in the 75% in mixed planting with 25% of other species had the longest dieback which could be the effects of partial shading from the mixed species. Mahroof et al. (2002) suggested that trees under partial shade may have lower nutrient levels in leaves and stems, requiring herbivores to consume more in order to satisfy their nutritional needs. Our experience in Ghana has generally found that shading decrease Khaya growth without significantly protecting the trees from Hypsipyla attacks (Opuni-Frimpong et al., in review 2006).

K. ivorensis in the 25% mixture with 75% of 3 other species were not attacked by Hypsipyla at the end of 3 years, but densities of K. ivorensis at 50% and higher mixed with 3 other species resulted in no significant differences from the attack levels in the monoculture. However, the pattern of attack (3.5/tree in monoculture, 1.6/tree in K. ivorensis 75% + 25% mixed and 1.2/tree K. ivorensis 50% + 50 % mixed) suggest that mixed plantations may reduce the attack levels on mahogany trees as predicted (Dupuy, 1995; Grijpma, 1976). Brunck and Mallet (1993), observed that using light shade protection during the early stages of growth in mixed plantations provides good tree form and reasonable growth. Although there were no significant differences in tree height, clear bole height and diameter growth between the monoculture and the mixed cultures, the lower density mahogany in mixed plantings had the least growth likely because these trees were shaded by the trees of other species which were more rapid growing. This supports Speight and Wylie’s (2001) suggestion that large scale commercial plantations, the benefits of monocultures are likely to outweigh disadvantages. Folgarait et al., (1995) found no significant differences in the infestation levels of defoliating moth larvae, diptera galls nor fungal spots on Stryphnodendron microstachyum (tropical tree) planted in mixed culture with 5 other species compared to a monoculture stand.

Dupuy (1995) predicted that in mixed plantings, the mixed species could provide both productivity benefits (i.e. improving soil nutrients to support growth) and protective functions. However, when we mixed K. ivorensis and K. anthotheca with Albizia which could improve soil fertility, there were no significant differences in the growth between the control (monoculture) and those planted in companion mixtures with Albizia. In a related study, Brunck and Mallet (1993) planted the Khaya species 2 years after Leucaena leucocephala (nitrogen fixing plant) had been planted in line planting, which showed better growth and form with lower Hypsipyla attack. Later pruning of L. leucocephala resulted in exposure of the mahogany trees which were then severely attacked.

Azadirachta indica (Neem) has been suggested to have the ability to repel shoot borer pest from Khaya species (Hauxwell et al., 2001) in mixed stands with their insecticidal properties (Cobbinah et al., 1999; Tuani et al., 1994; Howard, 1995). In our study, however, Neem trees in companion with the Khaya species at 50% X 50% did not decrease Hypsipyla attack compared to monoculture plantings. Hypsipyla attacks were 6.5/tree and 3.5/tree, respectively in the Albizia and Neem companion plantings on the K. anthotheca compared to 2.2/tree in the pure stand. There were higher attacks in the monoculture K. ivorensis but there were not significantly different from the companion plantings (3.5/tree in pure stand, 2.2/tree in Albizia companion plantings and 2.6/tree in Neem companion plantings). In a study by Wazihullah et al. (1996) not only did mixed-species planting record less stem borer attack but the presence of certain tree species in the mixed planting significantly influenced the level of attack positively or negatively. Snook and Negreros-Castillo (2004) reported that Hypsipyla attack in Swietenia (big leaf mahogany) stands increased with reduced competing vegetation. Non-cleaned, competing vegetation may be more diverse and able to support higher biological control agents than mixed planting with trees. Some studies have suggested that clean pure stands tend to have higher pest infestation because of a reduction in resources to support natural enemies (Russel, 1989; Pimental, 1961).

Our results support the suggestion that shoot borer tends to infest fast growing trees more than slower growing ones (Akanbi, 1986; Mahroof et al., 2002; Nowak et al., 2003). Although there were no significant differences in the height and diameter growth of K. anthotheca for the different fertilizer treatments and the control, the trees were relatively larger in size in the fertilizer treatment plots. The K. anthotheca plot which received 80 g/tree of NPK fertilizer attracted the highest attack (7.6 attacks/tree) resulting in longer dieback (31 cm dieback), compared to control with 2.2 attacks/tree and lower dieback (15 cm dieback). Despite the long dieback associated with high attack on fast growing trees treated with fertilizer, they maintained relatively superior diameter and height growth. The pattern of Hypsipyla attacks in the K. ivorensis fertilizer treatments were not different from the K. anthotheca treated with fertilizer. The percentages of trees attacked were higher in the fertilizer treated plots. However, attack per tree in the K. ivorensis plots treated with 120 g/tree was not significantly different from the control without fertilizer treatments. Trees in the K. ivorensis monoculture had the longest dieback from Hypsipyla attack. This suggests that the different species of mahogany may react differently to fertilizer treatments with regard to Hypsipyla attack.

5.0 Conclusions

In both K. anthotheca and K. ivorensis, the treatments that attracted the highest Hypsipyla attacks per tree also had the largest number of sprouted shoots as well as the highest number of dead shoots. Our results have demonstrated that Hypsipyla attack on Khaya species in mixed plantations may only be reduced significantly when Khaya is planted in very low density. It was evident from this study that fast growing mahoganies attracted the highest Hypsipyla attacks and responded to attacks with a greater number of sprouted shoots which was detrimental to tree form, though they maintained their vigor in growth. The results suggest that mixed plantations may not prevent Hypsipyla attack but they could improve the ability of mahogany trees to tolerate Hypsipyla attack by improving tree form. Fertilizer improved the growth of Khaya trees but these trees suffered the highest Hypsipyla attack leading to excessive branching.

6.0 Recommendations

Silvicultural management of the mahogany shoot borer needs research to identify optimal species-mix percentages, species choices and planting densities in mixed cultures. Silvicultural systems with mixed plantingsand fertilizer treatment should also be reexamined with lower densities of mahogany in mixed stands in different ecological regions to optimize these tools for integrated pest management of Hypsipyla shoot borer. Biological control agents for Hypsipyla should be evaluated with all silvicultural treatments to document their roles in the different systems. Especially the association between ants, mahogany trees and Hypsipyla shoot borer needs to be explored as field observations and literature point to a possible predation relationship between ants and Hypsipyla shoot borer. The use of female sex pheromones in managing pest must be evaluated with other silvicultural systems for integrated management of the Hypsipyla shoot borer.

Bibliography

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Major Research 5.

In vitro propagation technology for African mahoganies, Khaya anthotheca Welw. and K. ivorensis A. Chev.

E. Opuni-Frimpong1 D.F. Karnosky2, A.J. Storer2, and J.R. Cobbinah1

1 Forestry Research Institute of Ghana, University Box 63, Kumasi, Ghana. 2 School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Drive, Houghton MI 49931, USA E-mail address: [email protected] and [email protected] (E. Opuni-Frimpong)

Abstract

Continuous timber supply and conservation of African mahogany is threatened by overexploitation of natural forests and prevention of plantation establishments by the mahogany pest, Hypsipyla shoot borer. The objective of this study was to develop techniques for micropropagation of two African mahogany species, Khaya anthotheca and K. ivorensis to facilitate conservation and cloning of shoot-borer tolerant mahogany genotypes for reforestation in western Africa. Explants (shoot tips, nodal segments) were collected from juveniles trees (1-2years old) of greenhouse-grown Khaya anthotheca and K. ivorensis. Sterilized tissues were tested on woody plant medium and Murashige and Skoog medium supplemented with various growth regulators. Cytokinins benzyl-adenine (BA), Thidiazuron and Zeatin were used for shoot multiplication and elongation while auxins NAA and IBA were used to encourage rooting. Rooting of 73% for K. anthotheca and 62% for K. ivorensis occurred using 0.5mg/l NAA and 1mg/l NAA in woody plant media. Micropropagules survived and grew similarly to seedlings when transferred to the greenhouse. Successful micropropagation of Khaya could provide a platform for ex situ conservation of the few remaining elite trees in Ghana.

Key Words: Khaya species, in vitro culture, shoot multiplication, rooting, hormones

1.0 Introduction

The African mahoganies (Khaya species) are prime timber woods that have been overexploited over centuries in their native region (Taylor 1961; Hall and Swaine 1981; Parren and de Graaf 1995; Atuahene 2001) because of their valuable physical and chemical wood properties that make them ideally suitable for furniture, and industrial construction (Dunisch and Ruhmann 2006). Demand for the dark red mahogany wood for both local and international markets exceeds supply, and there is no comparable species available which are suitable substitutes for this mahogany wood. There is a strong desire to cultivate mahogany in plantations to sustain supply but damage by shoot borer is preventing successful large scale mahogany plantations (Floyd and Hauxwell 2001; Newton et al., 1993).

Hypsipyla attack has been observed to be less dependant on the season but pest activities depend on the flushing of new shoots which is available throughout the year in the African mahoganies in the moist tropical forest (Opuni-Frimpong, 2000). This suggests that successful plantations will depend largely on the ability of the planting stock of various mahogany species to tolerate or resist Hypsipyla infestation (Newton et al., 1993; Tchoundjeu and Leakey 2000). Thus, there is an urgent need to take advantage of the various modern technologies of vegetative propagation to optimize perpetuation of tolerant/resistance genotypes that may be identified in mahogany improvement programs.

Some in vitro techniques have the advantage of high multiplication rates but they generally also carry high initial investments in terms of training, expertise and equipment (Mayhew and Newton 1997). Continuous supply of mahogany timber is vital to sustainable forestry and related economic development in many tropical countries in Africa, Asia and Central America. Breeding for resistance is considered an attractive alternative method (Cornelius and Watt 2003) but it will only have impact on sustainable forestry if it is accompanied by development of successful mass propagation system to propagate Hypsipyla-tolerant trees. In vitro propagation (tissue culture) could be used for the large scale clonal propagation and conservation of selected clones of resistance genotypes that may be identified in mahogany improvement programs. Relatively few in vitro studies conducted on the mahoganies have had successful results (Lee and Rao 1988; Maruyama et al., 1989; Albarran et al., 1998; Venketeswaran et al., 1988; Maruyama & Ishii 1977, 1999; Numes et al. 2002). However, little information exists towards in vitro propagation of Khaya species.

Our objective was to develop an efficient in vitro method that is reproducible for mass propagation of the Khaya species.

2.0 Applied methodlogy

2.1 Source of Plant Material

African mahoganies, Khaya anthotheca and K. ivorensis stock plants originating from seeds collected in Ghana were the source of explants for the experiments. The seeds were used to establish stock plants which were grown in the greenhouse at the School of Forest Resources and Environmental Science of Michigan Technological University, Houghton, Michigan. The explants were collected from seedlings less than two years old in the greenhouse.

2.2 Explants Sterilization

Current growing, succulent and non-lignified shoots were collected from 1-2 year old K. anthotheca and K. ivorensis stock plants. The explants were surface sterilized with double distilled water with 20% commercial bleach, sodium hypochlorite solution (NaHCO3, 6% active chlorine) with 3-5 drops of Tween 20 (Sigma Co, USA) for 15-20 minutes. The sterilized explants (plant tissues) were then rinsed 3 times in double distilled water in a laminar flow hood. The plant tissues were dissected into nodal segments (1- 1.5 cm long) for in vitro culture.

2.3 Shoot Induction Media

Sterilized mahogany, non-lignified shoot tissues 1-1.5 cm long (Figure1A) were inoculated on woody plant media (WPM) (Lloyd and McCrown, 1980) and Murashige and Skoog media (MS) (Murashige and Skoog 1962) to compare explant health and shoot production. Cytokinin (6-benzyladenine, BA) was the growth regulating hormone used at concentrations (0.5, 1.0, 1.5, 4.0 mg/l) to initiate shoot development. The media were supplemented with 20 mg/l sucrose and 6.5 mg/l agargel (Agargel, Sigma Co, USA) as a gelling agent. The pH values were adjusted to 5.6-5.8 with either NaOH or HCl before autoclaving at 121oC for 15 min. The cultures were incubated in a walk-in growth chamber maintained at 22 ± 2oC under 16-h photoperiod and photo flux of 50 μmol m-2s-1 from Fluorescent tubes. The culture conditions for all experiment below were similar to this unless otherwise stated. We used the WPM media to test growth regulating hormones to maximize African mahogany plantlet regeneration as our initial results suggested our explants were healthier on this medium.

2.4 Shoot Multiplication and Elongation

Woody plant media supplemented with growth regulating hormones (cytokinins) 6- bensyladinine (BA), Trans-Zeatin [trans-6-(4-Hydroxy-3-methylbut-2-enylamino)purine] (ZEA) and Thidiazuron (TDZ) at different concentration were tested for axillary shoot generation from explants. The WPM was supplemented with 20 mg/l sucrose and 6.5 mg/l Agargel. The media were poured into 18 x 150 mm culture tubes, 65 x 65 x 77 mm culture vessels or 42 x 95 mm culture vessels after conditioning the medium to pH about 5.8 and autoclave as above. There were 15 to 25 replicates per treatment and each experiment was repeated 3 times. Data were collected on number of shoots initiated per explant, shoot frequency and shoot length after 6 weeks in culture.

(A) (B)

(C)

(D) (E)

Figure 1. In vitro culture of Khaya species from shoot tips and nodal segments. (A) Explants to be cultured, (B) shoot generation and multiplication, (C) Rooting shoots, (D) plantlets to be acclimatized, (E) Regenerated plants growing in the greenhouse 2.5 Rooting of Shoots

Regenerated shoots were inoculated on WPM supplemented with the auxins, 1- naphthaleneacetic acid (NAA) and 1H-indole-3-butyric acid (IBA), to evaluate the strength of the growth-regulating hormones in stimulating root development. The WPM was supplemented with 20 mg/l sucrose and 6.5 mg/l of Agargel with either NAA or IBA (0.5, 1.0, 1.5 mg/l) or the combination of the 2 were used. Each treatment had 15-25 replicates. Data were collected on frequency of rooting, number of roots per explant and length of longest root after 10 weeks.

2.6 Acclimatization of plantlets

Rooted plantlets were transferred to potting media made up of peat moss: perlite of (1:1) in 7 x 9 cm plastic pots. The potted plantlets were kept in a “high humidity” chamber with a transparent plastic sheet covering it and maintained at temperature of 25-30oC under 16-h photo period of 40 μmol-2s-1. The relative humidity was maintained at 85-95%. After 2-4 weeks all micropropagules were transferred to the greenhouse for monitoring for growth and survival.

2.7 Data analysis

Analysis of data were done by subjecting the data to analysis of variance (ANOVA) using the GLM procedure in SAS (SAS Institute 2004). Means were compared by using Tukey’s studentized range test  = 0.05, where the GLM-ANOVA showed significance. All experiments were conducted 3 times and data used in the analysis were means of independent experiments.

3.0 Presentation of the data

3.1Selection of Basal Salt (Media)

The tissue segments cultured on the WPM and supplemented with BA at all concentrations swelled at the terminal and lateral buds between 10 and 20 days which eventually produced adventitious shoots after 30 days (Figure 1b). In few occasions shoots tips elongated (data not provided) before generating additional shoots from the buds in the nodes. Shoots were generated in 6.6 – 88% of the K anthotheca explants inoculated on WPM (Table 1) while 5.7 – 80.1% explants of K. ivorensis generated shoots on the same type of media. Treatments with relatively high concentrations of BA (1.5-4.0 mg/l) produced callus at the explants base. Swelling buds also sometimes produced callus which developed fewer shoots after 10 weeks culture than those Explants without callus. Callus development was observed more in K. anthotheca culture than in the K. ivorensis experiments. In both K. anthotheca and K. ivorensis experiments, treatments supplemented with BA at 0.5 mg/l had the most tissue segments that generated shoots (Table 1).

Table 1. Effect of culture media WPM (Lloyd and McCrown, 1980) and MS (Murashige and Skoog 1962) supplemented with different concentrations of 6-bensyladinine (BA) on percentage of explants surviving and generating shoots after 10 weeks in culture Nodal segment generating shoots (%) Survival (%) ______Basal BA (mg/l) Ka Ki Ka Ki Medium WPM 0.0 6.6d (0.8) 5.7c (2.7) 43.3c (6.4) 45.0b (4.0) 0.5 88.0a (4.3) 80.1a (2.9) 91.7a (2.1) 81.3a (2.8) 1.0 66.7b (4.4) 64.3ab (2.3) 86.0ab (3.0) 78.7a (2.0) 1.5 39.7c (3.1) 55.4b (3.3) 71.3b (2.4) 76.0a (3.6) 4.0 6.6d (1.2) 17.3c (6.3) 51.0c (2.5) 53.2b (2.7) Main Effects* <0.0001 <0.0001 <0.0001 <0.0001 MS 0.0 4.0b (1.2) 4.0d (0.5) 54.3ab (2.1) 52.0a (3.5) 0.5 27.6a (1.4) 31.2a (1.9) 64.0a (4.1) 64.2a (2.1) 1.0 32.7a (8.9) 19.1b (2.0) 52.4abc (4.9) 64.0a (3.2) 1.5 28.3a (4.4) 12.3 b (0.8) 46.3bc (1.9) 61.3a (3.3) 4.0 12.4ab (1.4) 6.6cd (1.2) 39.0c (1.5) 37.0b (3.6) Main effects* 0.0053 0.0001 0.003 0.0005 Data from the WPM and MS media were analyzed separately. Values in a column with the same letter are not significantly different. Numbers in parenthesis are standard errors. Ka = Khaya anthotheca and Ki = K. ivorensis *P-values of main effects of ANOVA using GLM procedures in SAS

Explants inoculated on MS media and supplemented with BA had the most buds swelling after 15-22 days on culture media and shoots were generated after 35 days. The K. anthotheca explants had 4-33% generating shoots after 10 weeks while 4-31% of the K. ivorensis explants produced shoots on similar media within the same time period. Again, K. anthotheca and K. ivorensis in the MS media supplemented with 4.0 mg/l of BA produced more callus which generated fewer shoots after 10 weeks in culture. In the control treatments without growth regulators, K. anthotheca and K. ivorensis tissue segments cultured on WPM media and MS media had the least shoot generation, though most of the tissues remained fresh on the media at the end of data collection of 10 weeks.

The survival of the plant tissues in the culture media followed the pattern of the ability to generate shoots (Table1). Treatments that stimulated more tissues to generate shoots also supported the best survival of Explants after 10 weeks in the culture media.

3.2 Tissue Segment Types

Table 2 demonstrates that the part of the plant cultured affects the number of shoots that can be generated from the tissue segments with 0.5 mg/l of PGRs, BA and ZEA supplemented in WPM. For both K. anthotheca and K. ivorensis, the numbers of regenerated shoots were consistently higher from the nodal segments compared to the shoot tips. Shoot tips only produced more shoots in situations where the tissue segment cultured elongated to have 2-3 internodes and then each lateral bud generated at least one shoot.

Table 2. The effect of BA (0.5 mg/l) and Zeatin (1.0 μm) on in vitro generation of shoots from shoot tips and nodal segments of K. anthotheca and K. iverensis seedlings less 1-2 years old on WPM media. Species Propagules Cytokinin % culture number of Shoot with shoots shoots/Explant length (cm) K anthotheca Shoot tip BA 91.0 (4.1) 1.5(0.2) 2.2 (0.2) Node BA 93.2 (3.5) 3.4(0.9) 1.8 (0.1) Shoot tip ZEA 82.3 (2.3) 1.3 (0.2) 2.0 (0.3) Node ZEA 89.6 (4.7) 3.1 (0.6) 1.7 (0.1) K. ivorensis Shoot tip BA 77.3 (3.9) 1.2 (0.2) 1.9 (0.2) Node BA 87.0 (3.5) 3.0 (0.1) 1.6 (0.2) Shoot tip ZEA 76.5 (2.4) 1.1 (0.1) 1.8 (0.3) Node ZEA 88.7(3.2) 3.0 (1.1) 1.6 (0.2) Data from the WPM and MS media were analyzed separately. Numbers in parenthesis are standard errors.

3.3 Shoot Induction and Multiplication

The cycle of Khaya tree generation by in vitro culture of explants from 1-2 year old African mahoganies growing in the green house is shown Figure 1. Initiation and multiplication of shoots is demonstrated in Figure 1B. BA, ZEA, and TDZ were all able to induce explants to generate shoots except TDZ at 4.0 μM which had no shoots after 10 weeks in culture (Table 3). In the K. anthotheca experiments, treatments with 0.5 mg/l BA and 1.0 mg/l ZEA had the highest number of explants produce shoots (91 and 92% respectively) (Table 3). The same patterns of shoot generation were observed for the tissue segments cultured from K. ivorensis plant material. TDZ induced callus production in most tissues resulting in the lowest shoot production with this hormone (Table 3). Analysis of variance revealed significant differences (P<0.05) between the hormonal treatments.

Table 3. Effect of different plant growth regulators (cytokinins) on generating of shoots from nodal segments after 10 weeks on WPM culture media. Nodal segments producing shoots (%)

______

Species Conc. (mg/l) BA ZEA TDZ K. anthotheca 0.5 91.0a (2.1) 82.3ab ( 4.3) 22.7a (3.7) 1.0 67.3b (2.8) 91.7a (3.8) 11.6b (1.8) 1.5 39.1c (1.9) 71.2b (2.3) 6.0bc (0.8) 4.0 12.3d (3.1) 38.3c (4.4) 0.0 (0) Main effects* <0.0001 <0.0001 0.0003 K. ivorensis 0.5 92.6a (2.9) 72.7a (2.2) 23.6a (4.1) 1.0 74.0b (3.7) 79.3a (2.6) 7.6b (1.4) 1.5 52.7c (5.3) 54.5b (3.5) 6.3b (1.8) 4.0 11.3d (2.3) 11.6c (2.7) 0.0 (0) Main effects* <0.0001 <0.0001 0.0003 K. ivorensis and K. anthotheca data were analyzed separately. Values in a column with the same letter are not significantly different. Numbers in parenthesis are standard errors. *P-values of main effects of ANOVA using GLM procedures in SAS

3.4 Rooting of shoots

Rooting of plantlets produced in vitro were higher on WPM supplemented with 0.5 mg/l NAA for both K. anthotheca and K. ivorensis (Table 4 and Figure 1C). Roots were initiated on treatments with 0.5 mg/l of NAA, after 14 and 17 days for K. anthotheca and K. ivorensis, respectively. K. ivorensis had the highest number of roots on WPM supplemented with 1.0 mg/l NAA (3.0 roots/plantlet) while K. anthotheca had the largest root number with 0.5 mg/l NAA (2.7 roots/plantlet). There were significant differences between the treatments (P < 0.05) for both plant species. The combination of NAA and IBA at 0.5 x 0.5 mg/l resulted in very good rooting. The numbers of roots were not significantly different from rooting numbers of K. anthotheca plantlets cultured on WPM supplemented with NAA 0.5 mg/l. The rooting of plantlets varied from 23 – 73% for the treatments used for K. anthotheca experiments while K ivorensis experiments differed from 19-63% for the same treatments. Root lengths were also significantly different between treatments for both K. anthotheca and K. ivorensis (Table 4).

Rooted explants were transferred to potting media made up of peat moss: perlite of 1:1 (Figure 1D). Plantlets were acclimatized at high relative humidity (85-95%) for two weeks in a mist chamber. 100% percent survival was recorded for rooted plantlets 3 months after transfer into the greenhouse. Vigorously growing propagules generated from in vitro culture are shown in Figure 1E.

Table 4. The effect of NAA and IBA on rooting of K. anthotheca and K. ivorensis shoots generated in vitro after 10 weeks on culture media. Numbers in parenthesis are standard errors. Species NAA-IBA Number of Root length (cm) Conc. (mg/l) % rooted Roots/Explant K. anthotheca 0.5 – 0.0 72.6a (5.0) 2.7 a (0.5) 12.1a (1.2) 1.0 – 0.0 64.7ab (2.9) 2.5ab (0.3) 7.8bcd (0.3) 1.5 – 0.0 34.3de (3.5) 1.4ab (0.1) 6.7cd (0.4) 0.0 – 0.5 49.8cd (2.0) 1.9ab (0.4) 10.0abc (0.6) 0.0 – 1.0 51.0bcd (2.5) 1.7ab (0.2) 10.6ab (0.4) 0.0 – 1.5 22.7e (4.6) 1.3b (0.1) 6.3d (0.5) 0.5 – 0.5 68.0ab (3.1) 1.8ab (0.2) 11.8a (0.8) Main effect* <0.0001 0.03 <0.0001 K. ivorensis 0.5 – 0.0 63.3a (4.4) 2.1b (0.1) 11.2 a (0.6) 1.0 – 0.0 48.7ab (2.3) 3.0a (0.2) 8.7abc (1.2) 1.5 – 0.0 28.4cd (4.9) 1.3b (0.1) 7.3c (0.4) 0.0 – 0.5 41.7bc (2.7) 1.8b (0.3) 8.3bc (0.8) 0.0 – 1.0 49.0ab (4.1) 1.7b (0.2) 9.0abc (0.5) 0.0 – 1.5 19.1d (2.1) 1.4b (0.5) 6.6c (0.3) 0.5 – 0.5 57.6ab (5.0) 1.7b (0.1) 10.3ab (0.4) Main effects* <0.0001 0.0002 0.0003 Data from the WPM and MS media were analyzed separately. Values in a column with the same letter are not significantly different. Numbers in parenthesis are standard errors. *P-values of main effects of ANOVA using GLM procedures in SAS

4.0 Analysis and interpretation of the data results

Micropropagation of trees from juvenile plants sources has been successful in several plant species including some mahoganies (Mroginski et al., 2003; Vila et al., 2004; Numes et al., 2002, 2003; Maruyama et al., 1989; Eeswara et al., 1998). In all these cases, there were manipulation of the basal salt and the plant growth regulators, cytokinins and auxins. Mroginski et al. (2003) found the best shoot generation of the Australian red cedar (Toona ciliata) on MS medium at ¼ strength supplemented with 0.1 mg/l IBA and 0.5mg/l BAP. Shoots of Azadirachta indica also in the Meliaceae were successfully generated from full strength MS medium supplemented with 1mg/l of BA (Eeswara et al., 1998). A 5-7 folds shoot multiplication was found in Swietenia macrophylla on WPM with 10 μM of ZEA (Maruyama and Ishii., 1997). Our results reported here indicate that the WPM basal salt was the best for in vitro propagation of K. anthotheca and K. ivorensis based on the hormone concentrations tested. Multiplication of shoots resulted in 5-8 and 5-6 fold increases of shoots during the second subculture cycle of K. anthotheca and K. ivorensis, respectively. It has been suggested that the interaction of culture media, with respect to nutrients, ionic strength, hormone type and concentration and physiological status of the explants may explain the differences in the results obtained from various studies (Nunes et al., 2002).

Our results of higher shoot generation per explant from buds on nodal segments are in agreement with observations made by Mroginski et al. (2003) and Ajithkurmar and Seeni (1998). On a few occasions, terminal buds elongated before differentiating into plantlets leading to 2-3 shoots per terminal bud. In the case of lateral buds, they typically initially swelled and differentiate into 2 or more shoots. The generation of shoots was influenced significantly by the composition of the culture medium, especially the cytokinins and their concentrations. The effectiveness of the cytokinins BA and ZEA in stimulating shoot proliferation and multiplication has been reported (Maruyama and Ishii., 1999). The development of a few shoots from cultured explants in our system without hormone supplements suggests that endogenous level of cytokinins were sufficient to stimulate shoot generation in some explants.

K anthotheca had the best rooting results on WPM containing 0.5 mg/l NAA while K. ivorensis had the best rooting on WPM containing 1.0 mg/l NAA. Higher auxin (NAA and IBA) concentrations might have suppressed morphorgenetic activity resulting in lower rooting rates as suggested by Ajithkurmar and Seeni (1998). Nunes et al. (2002) achieved 73% rooting of Cedrela odorata (Meliaceae) on half strength WPM using 2.5 μM IBA after 30 days in culture. Rooting of Toona ciliata was obtained in enriched MS media using 0.1 mg/l IBA to achieve 62 ± 5% rooting of explants obtained from 2-year-old trees. Thus different species appear to respond differently to concentrations of auxins suggesting that the individual species may have inherent traits making them amenable to specific culture conditions. Differential endogenous levels of auxins in explants would require them to respond to hormones differently (Ajithkurmar and Seeni 1998). Ofori et al., (1996) suggested that some tropical trees may inherently have the ability to produce sufficient auxins to support rooting of vegetative parts without hormone supplements.

5.0 Conclusions

The best shoot multiplication and elongation medium for in vitro propagation of the Khaya species was woody plant media supplemented with 0.5mg/l 6-bensyladinine (BA). 1- naphthaleneacetic acid (NAA) of 0.5 mg/l was also the best for rooting.The successful in vitro culture of the African mahoganies provides the basis for manipulation of the protocol for mass production of African mahogany clones that will be identified to be resistant to shoot borer Hypsipyla robusta.

6.0 Recommendations

The technology can also be a valuable tool in developing techniques for ex situ conservation of the mahoganies. The protocol developed could be useful for tree improvement programs including genetic engineering of insect resistant genes into the African mahogany to control the devastating mahogany pest, Hypsipyla. We are now examining the capability of 3-5 year- old trees to be micropropagated as we routinely make our evaluation of Hypsipyla shoot borer by age 5.The protocol needs to be optimized to propagate 4 to 6-year-old mahogany trees which are old enough to demonstrate sustained tolerance to Hypsipyla attack. Transformation of insect resistant genes (e.g. Bt-gene) into mahogany genome should be explored.

Bibliography

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Major Research 6.

Key roles of leaves, stockplant age, and auxin concentration in vegetative propagation of two African mahoganies: Khaya anthotheca and Khaya ivorensis:

E. Opuni-Frimpong1, D.F. Karnosky2, A.J. Storer2, and J.R. Cobbinah1 1Forestry Research Institute of Ghana, University Box 63, Kumasi, Ghana. 2 School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Drive, Houghton MI 49931, USA E-mail address: [email protected] and [email protected] (E. Opuni-Frimpong)

Abstract Leaf area, IBA concentration and age of stock plants were all found to be important factors for successful rooting for vegetative propagation using single-node cuttings of the two main African mahogany species: Khaya anthotheca and K. ivorensis. Cuttings with leaf area of 30-50 cm2 had the best rooting percentage and cuttings with about 30 cm2 had the most number of roots per cutting in K. anthotheca. K. ivorensis, cuttings with 10-30 cm2 leaf area had the highest rooting percentage. Cuttings collected from one-year-old stockplants recorded the highest rooting percentage and largest number of roots per cutting. Cuttings from 3-year- old stockplant of the same seeds sources had the lowest rooting suggesting aging negatively impacted rooting ability. The effect of auxin concentration, on rootability was examined with cuttings of K. anthothec. An IBA concentration of 0.8% was the best exogenous auxin concentration for percentage rooting, number of roots per cutting and the length of the longest root per cutting.

Key Words: Khaya species, vegetative propagation, rooting, cloning stockplants, cuttings

1.0 Introduction

African mahoganies, Khaya ivorensis and K. anthotheca, are recognized among the most valuable tropical hardwood species, together with other species of the family Meliaceae. Mahoganies contribute significantly to both domestic and international markets, providing major a source of revenue to countries where they occur (Atuahene 2001; Dunish and Ruhmann 2006; Dupuy 1995). The appealing characteristics of mahogany wood, including its pinkish to dark brown color and physical properties which makes it fairly easy to work with, and the fact that the wood finishes well and takes fine polish (Irvine 1961; Dunisch and Ruhmann 2006) all make mahogany a highly desired wood for furniture and carpentry. Apart from the use of mahogany wood in the furniture making, construction industry, carpentry, flooring, paneling, and decorative veneer in boats and ships, the bark is used in dyeing and tanning leather. The bark of the bole is used medicinally to manage malaria, repel and kill mosquitoes and to make bitter bark, which is similar to quinine, and is used for cold and flu treatment (Taylor 1960). These desirable qualities put excessive demand on the African mahoganies resulting in dwindling of the natural resource base of the mahogany (Alder 1989; Hall and Swaine 1981; Atuahene 2001). Natural regeneration is generally poor as the seeds lose viability between 2-3 weeks under natural conditions (Taylor 1960; Swaine et al. 1996) and survival of seedlings is poor under the forest canopy as Khaya species are light demanding (Hawthorne 1990). Efforts to restore the depleted mahogany resource base by plantation culture have been thwarted by persistent attack of the mahaogny shoot borer Hypsipyla (Newton et al. 1993; Floyd and Hauxwell 2001; Opuni-Frimpong et al. 2005).

There is an increasing demand to do range-wide genetic selection from the sparse mahogany population left in the wild for genetic resistance to Hypsipyla which can be incorporated into an integrated pest management program for the control of Hypsipyla species (Grijpma 1976; Newton et al. 1993; Floyd and Hauxwell 2001; Opuni-Frimpong et al. 2005). Successful planting of the offspring of elite trees resistant to Hypsipyla will require an efficient propagation system in place to mass propagate superior genotypes. With vegetative propagation methods, the produced offspring is genetically identical to the stock plant. Different species of Meliaceae (mahogany) have been successfully propagated by rooting leafy cuttings; Khaya senegalenses and K. ivorensis (Tchoundjeu and Leakey, 1996; 2000; Limpiyaprapant et al., 1996) and Swietenia mahogani (West Indies mahogany) (Howard et al., 1990).Various propagation systems have been used, including low-technology non-mist propagators (Leakey et al., 1990). Mayhew and Newton (1998) noted that if mahoganies were to be propagated on a commercial scale, detailed information is required on the appropriate treatments which should be applied to both the stock plant and the cuttings in order to obtain consistently high rooting success.

In the mass production of plants, the cost of propagation is very important in the decision making (MacDonald, 1993). Micropropagation of mahogany is possible (Maruyama and Ishii, 1999; Nunes et al., 2002) but it requires high-tech facilities and well-trained personnel which is lacking in most places where mahogany can be grown. The previous studies of vegetative propagation on the African mahoganies considered K. ivorensis seed sources from Nigeria (Tchoundjeu and Leakey., 1996). K. anthotheca, which grows faster than K. ivorensis, could be a very good candidate for large-scale plantation as resistant trees are identified and cloned. Our objective was to develop a vegetative propagation system testing the effect of stockplant age, auxin concentration, and leaf area on rooting of single-node cuttings of K. anthotheca and K. ivorensis with seed sources from Ghana.

2.0 Applied methodology

2.1 Stockplant Production and Management

African mahoganies, K. anthotheca and K. ivorensis stock plants originating from seeds collected in the moist semideciduous forest of Ghana (Hall and Swaine 1981) were the source of explants for the experiments. The seeds were germinated and grown on potting media to establish stock plants in the greenhouse at the School of Forest Resources and Environmental Science of Michigan Technological University, Houghton, Michigan. Seeds of each species, bulked as described by Tchoundjeu et al. (2002), were germinated on peat moss and watered daily. Two weeks after germination, the seedlings were transferred into potting media composed of 21 l of topsoil, 15 l. of perlite, 10 l of peat moss, 70 ml of lime, 70 ml of super phosphate and 10 ml of plant food/fertilizer; Miracle-Gro (Scotts Miracle-Gro products, Inc., USA). Pest (insects, mites and fungi) were controlled with Diazinon (Truserv, Chicago, USA), Avid 0.15EC (Novartis crop protection Inc. USA), fungicide 3336F (Cleary chemical, USA) biweekly. Liquid iron (Voluntary Purchasing Group Inc., USA) and fertilizer; Miracle- Gro (Scotts Miracle-Gro products, Inc., USA) were applied monthly. Stock plants were maintained at about 30 cm in height.

2.2 Cuttings Preparation and Propagation setup

Actively growing shoots were harvested and dissected into single-node cuttings. The leaf laminar was trimmed with scissors to 30 cm2 unless otherwise stated. Indole-3-butyric acid (IBA) in Hormodin 3 rooting powder (Merck Chemical Division, PA, USA) was used in treating all cuttings to stimulate rooting unless other wise stated. The bases of the cuttings were cut squarely (Tchoundjeu et al. 1996) and were dipped in Hormodin 3 (IBA) as described by Howard et al. (1990). The rooting media was composed of peat moss: perlite at 2:3 in plastic propagation trays. Cuttings treated with IBA were set in the rooting media and kept in a “high humidity” chamber which was a wooden frame covered with a transparent plastic sheet. Conditions in the chamber were maintained at a temperature of 25-30oC under 16-h photoperiod of 40 μmol-2s-1. The relative humidity was maintained at 85-95% using a water vaporizer system.

2.3 Effects of Leaf Area (Experiment 1)

We tested the effect of 4 different leaf areas (0, 10, 30, 50 cm2) on the rooting of cuttings from 2-year-old stockplants of Khaya anthotheca and K. ivorensis. Eight cuttings of each species were taken from 30 stockplants of each of 2 species and randomly distributed equally to each of the treatments. Each of the 4 leaf area treatments was allocated twenty cuttings in each replicate. Each experiment was repeated 3 times. We trimmed the leaf to the required area by using templates of known sizes (Tchoundjeu et al., 2002). The bases of the cuttings were wetted, dipped in Hormodin 3 (0.8% IBA concentration) and set into the rooting media. Data were collected on number of roots per cutting, proportion of cuttings rooted, root length and cutting survival after 10 weeks.

2.4 Effect of Age of the Stock Plant (Experiment 2)

Cuttings collected from 3 different aged stockplants of K. anthotheca and K. ivorensis were tested for rooting. The stockplants from identical seed sources were ages 1, 2 and 3 years. Three cuttings were taken from 20 stockplants of each age and the experiment was replicated 3 times. The leaf on each cutting was trimmed to 30 cm2. The cuttings were treated with IBA of 0.8% and set into a mixture of peat moss and perlite as rooting medium and placed in the “high humidity” chamber. Data were collected as described in experiment 1.

2.5 Effects of Auxin Concentration (Experiment 3)

We tested 4 concentrations of IBA in this experiment: 0, 0.1%, 0.3% and 0.8% with cuttings of K. anthotheca. Eight cuttings were taken from 30 stockplants and randomly distributed equally to each of the treatments. Each of the 4 IBA concentrations was allocated to twenty cuttings in each experiment. The experiment was repeated 3 times. The squarely cut base of the cutting were dipped in Hormodin 1 (0.1% IBA), Hormodin 2 (0.3% IBA) and Hormodin 3 (0.8% IBA) powder and the control treatment without IBA. The treated cuttings were then set into a rooting medium mixture of peat moss and perlite and placed in the “high humidity” chamber area. Assessment and data were collected as in experiment 1.

2.6 Analysis of Data

Data collected from rootings per cutting, percentage rooting, root length and survival of cuttings were analysed using analysis of variance of the GLM procedures in SAS (SAS Institute 2004). Where significant differences were observed between treatments, the means were separated by comparing them using the Tukey’s studentized range test, α = 0.05.

3.0 Presentation of the data

3.1 Effects of Leaf Area

Leaf area significantly (P < 0.001) affected number of roots per cutting, rooting percentage, root length and survival of cuttings in both K. anthotheca and K. ivorensis. None of the leafless cuttings rooted and more than 80% and 90% of leafless K. anthotheca and K. ivorensis cuttings died before week 10 (Tables 1 and 4; Figure1a). The larger leaf (30 and 50 cm2) areas had the highest rooting percentage with the 30 cm2 having the most roots per cutting in K. anthotheca. K. ivorensis cuttings with leaf areas from 10 to 30 cm2 had the largest rooting percentage and were significantly different (P<0.001) from the 50 cm2 leafy- cuttings. Root lengths in both species were influenced by the leaf area with root length increasing with leaf area. Most cuttings with some amount of leaf survived and analysis of variance did not detect any differences between cuttings with 10 to 50 cm2 at P <0.05.

Table 1. Effects of leaf area on number of roots per cutting, root length, survival of cuttings and proportion rooted, for Khaya anthotheca cuttings after 10 weeks in propagation medium. Leaf area No. of Roots/ Rooting Length of longest Survival of (cm2) cutting percentage root (cm) cuttings (%) 0 0.00b ± 0.00 0.0c ± 0.00 0.00c ± 0.00 18.3b ± 4.41 10 2.77a ± 0.12 51.7b ± 1.67 7.71c ±1.03 100a ± 0.00 30 2.90a ± 0.27 65.3a ± 2.91 14.63a ± 0.85 100a ± 0.00 50 2.87a ± 0.30 75.0a ± 2.89 15.57a ± 0.98 91.7a ± 6.01 Main effects* 0.0001 0.0001 0.0001 0.0001 *P-values of main effects of ANOVA using GLM procedures in SAS

Table 2. Effects of stock plant age on number of roots per cutting, root length, survival of cuttings and proportion rooted, for Khaya anthotheca cuttings after 10 weeks in propagation medium. Stock-plant age No. of Roots/ Rooting Length of longest Survival of (Years) cutting percentage root (cm) cuttings (%) 1 4.5a ± 0.62 80a ± 2.89 17.7a ± 1.58 100a ± 0.00 2 2.7b ± 0.22 76ab ± 2.08 13.9a ± 1.91 96a ± 2.11 3 2.9ab ± 0.09 66b ± 3.06 15.4a ± 0.72 98a ± 1.67 Main effects* 0.029 0.026 0.274 0.259 *P-values of main effects of ANOVA using GLM procedures in SAS

(a)

(i) (ii) (iii)

(iv)

(b)

Figure 1. Rooting of Khaya anthotheca; (a) effect of leaf area on rooting cuttings [(i) 50 cm2 leaf, (ii) 30 cm2 leaf, (iii) 10 cm2 leaf, (iv) 0 cm2]; (b) effect of IBA concentration on rooting of K. anthotheca (Ho – 0% IBA, H1 - 0.1% IBA, H2 - 0.3% IBA and H3 – 0.8%)

3.2 Stockplant age

With K. anthotheca, age of stockplants affected the number of roots per cutting and rooting percentage of cuttings but did not affect root length or survival of cuttings (Table 2). However, with K. ivorensis, age of stockplant influenced the number of roots per cutting, survival of cuttings and root length significantly but had no significant effect on rooting percentage of cuttings (Table 5). Cuttings from the younger aged stockplants had more roots per cutting.

Table 3. Effects of concentration of active ingredient Indole-3-butyric acid (auxin) on number of roots per cutting, root length, survival of cuttings and proportion rooted, for Khaya anthotheca cuttings after 10 weeks in propagation medium. Auxin Conc. No. of Roots/ Rooting Length of longest Survival of (%) cutting percentage root (cm) cuttings (%) 0.0 2.43c ± 0.03 55c ± 2.52 6.07b ± 0.23 92.33a ± 3.93 0.1 2.73bc ± 0.09 65b ± 4.41 6.37b ± 0.58 97.15a ± 2.67 0.3 3.00bc ± 0.06 81a ± 1.93 10.2a ± 0.57 98.23a ± 1.67 0.8 3.17a ± 0.15 82a ± 1.65 12.77a ± 0.99 95.24a ± 4.76 Main effects* 0.002 0.0002 0.0002 0.640 *P-values of main effects of ANOVA using GLM procedures in SAS

Table 4. Effects of leaf area of on number of roots per cutting, root length, survival of cuttings and proportion rooted, for Khaya ivorensis cuttings after 10 weeks in propagation medium. Leaf area No. of Roots/ Rooting Length of longest Survival of (cm2) cutting percentage root (cm) cuttings (%) 0 0d ± 0.00 0.0c ± 0.00 0.0c ± 0.00 9.96c ± 1.93 10 1.93b ± 0.09 90.63a ± 1.21 7.40b ± 0.69 100a ± 0.00 30 2.33a ± 0.1 95.55a ± 4.45 15.71a ± 0.32 100a ± 0.00 50 1.33c ± 0.08 68.33b ± 4.41 15.23b ± 0.45 95a ± 2.87 Main effects* 0.0001 0.0001 0.0001 0.0001 *P-values of main effects of ANOVA using GLM procedures in SAS

Table 5. Effects of age on number of roots per cutting, root length, survival of cuttings and proportion rooted, of Khaya ivorensis cuttings after 12 weeks in propagation medium. Stock-plant age No. of Roots/ Rooting Length of longest Survival of (Years) cutting percentage root (cm) cuttings (%) 1 3.40a ± 0.15 75.00a ± 2.87 16.73a ± 0.7 86.59ab ± 0.87 2 2.16b ± 0.12 73.33a ± 6.01 20.11ab ± 0.98 95.00a ± 5.0 3 1.83b ± 0.29 73.10a ± 4.37 13.17b ± 2.26 75.67b ± 5.36 Main effects* 0.0044 0.9510 0.044 0.0495 *P-values of main effects of ANOVA using GLM procedures in SAS 3.3 Effect of Hormone Concentration

Rooting hormone concentration significantly affected number of roots per cutting, rooting percentage and root length but the differences between treatments for cutting survival was not statistically significant (Table 3). The number of roots per cutting increased with increasing concentration of IBA. Rooting percentage and root length followed a similar trend (Figure 1b). The control cuttings without IBA treatment had the lowest rooting percentage and roots per cutting but over 90 % of the cuttings survived at the end of the study period.

4.0 Analysis and interpretation of the data and results

The influence of leaf area in rooting of cuttings has been reported in a number of tropical trees (Tchoundjeu et al., 2002; Tchoundjeu and Leakey, 1996; Ofori et al., 1996; Leaky et al., 1982). Our results indicated that increasing leaf area strongly improved rooting percentage and root length of K. anthotheca. However, number of roots per cutting, and survival of cuttings appeared to be affected either by presence or absence of leaf and not the size of the leaf. Leakey et al., (1982) attributed the rooting inability of Triplochiton scleroxylon (tropical tree) cuttings without leaves to rapid depletion of carbohydrates in the stem, suggesting that leaf was the main source of carbohydrate in the cuttings. Leafless cuttings that survived through the study period did not root suggesting that presence of a leaf may have an additional physiological function to stimulate rooting apart from supply of carbohydrate. K. anthotheca cuttings had the best rooting with leaf area of 30-50 cm2 compared to 10-30 cm2 for K. ivorensis cuttings. The results from our K. ivorensis experiments were similar to earlier findings (Tchoundjeu and Leakey, 1996). The differences in optimum leaf area for rooting of cuttings of K. ivorensis and K. anthotheca could be adaptation of the two species to maximize available light. Naturally, K. ivorensis has smaller leaves compared to K. anthotheca (Hawthorne , 1990). Tchoundjeu et al., (2002) suggested that the inherent small leaves of Prunus africana might have contributed to the smaller leaf area required for rooting.

Exogenous application of auxins to the base of cuttings positively impacted rooting percentage, rooting number per cutting as well as rooting length in our study. Our observations were in agreement with previous reports on tropical trees including Prunus africana (Tchoundjeu et al., 2002), Milicia excelsa (Ofori et al., 1996), and Tectona grandis (Husen and Pal, 2006). The optimum auxin concentration for the rooting of K. anthotheca in this study was 0.8%. Ofori et al. (1996) had the best rooting with 0.2 - 0.4% application of IBA to Milicia excelsa cuttings, while 0.4% IBA was reported to be the best for rooting Triplochiton scleroxylon (Leakey et al., 1982). Thus, different species appear to require a different concentration of exogenous auxins to stimulate rooting. The rooting of cuttings without auxin supplements in this study may be attributed to endogenous supply of auxins as suggested in other tropical trees (Ofori et al., 1996; Leakey, 1990; Leakey et al., 1990). Despite the positive influences of the auxin application on root ability of cuttings, exogenous auxins had no effect on survival of the cuttings.

It is critically important that we are able to vegetatively propagate 3-5 year old Khaya trees as it takes until age 3-5 to make an accurate determination of the Hypsipyla shoot borer tolerance. Reductions in rooting potential with aging of many species have been documented (Husen and Pal 2006; Bhardwaj and Mishra 2005; Stenvall et al. 2004; Ofori et al. 1996). Several reasons have been assigned to decreasing rooting ability of aging and matured stockplant cuttings. The reasons include decreased sensitivity of the tissue to auxins with biological aging of the stock plant, accumulation of rooting inhibitors and reduction in endogenous auxin content and/or root promoters (Hartmann et al. 1997; Ofori et al. 1997; Husen et al. 2006). The results of this study support the reported observations. K. anthotheca rooting percentage and number of roots per cutting for cuttings from stockplants from a common seed sources decreased with increasing age and both variables differed significantly between treatments. With K. ivorensis, aging significantly affected all the variables assessed except percentage of rooted cuttings. The cutting back of the stock plant might have contributed to aging not having any effect in the percentage of rooting of cuttings in K. ivorensis. Ofori et al. (1997) observed improvement in rooting of cuttings when 10-year-old Milicia excelsa trees were reinvigorated by coppicing.

5.0 Conclusions

Successful vegetative propagation in Ghana will be very useful to clone field tested Hypsipyla-tolerant mahogany trees. Leaf area, stockplant age and auxins IBA at concentration (0.8%) were very important in rooting both Khaya anthotheca and K. ivorensis cuttings. Cuttings only rooted when there was some amount of leaf area present on the explant. Cuttings from younger plants rooted better than did cuttings from older plants. Vegetative propagation of African mahoganies, demonstrated in this study, could provide the opportunity to mass propagate elite trees in tree improvement programs for production forestry and ex situ conservation.

6.0 Recommendations

Further studies should be carried out on being able to create better rooting for older cuttings to allow for this technology to be widely used in mass propagation of superior Hypsipyla shoot borer tolerant genotypes.

Bibliography

Alder, D., 1989. Natural forest increment, growth and yield. In: Ghana Forest Inventory Project Seminar Proceedings. (J.LG. Wong; ed) Ghana Forestry Commission/Overseas Development Administration. 29-30 March 1989. Accra, Ghana. 101 pp Atuahene, S.K.N., 2001. The forest resources of Ghana and research on Hypsipyla robusta (Moore) (Lepidoptera: Pyralidae) control in mahogany plantations in Ghana. In: Floyd, F. and Hauxwell, C. (Eds.) Proceedings of an International Workshop on Hypsipyla shoot borers of the Meliaceae, Kandy, Srilanka, 1996. ACIAR Proceedings No. 97 Canberra, 58-62. Bhardwaj, D.R. and Mishra, V.K., 2005. Vegetative propagation of Ulmus villosa: effects of plant growth regulators, collection time, type of donor and position of shoot on adventitious root formation in stem cuttings. New Forests 29:105- 116. Dunisch, O. and Ruhmanm, O., 2006. Kinetics of cell formation and growth stresses in the secondary xylem of Swietenia mahogany (L.) Jacq. and Khaya ivorensis A. Chev. (Meliaceae). Wood Science Technology 40:49-62. Dupuy, B., 1995. Mixed plantations in Cote d’Ivoire rain forests. Bois et Forests des Tropiques 24:33–43. Floyd, R. and Hauxwell, C., 2001 Proceedings of an International Workshop on Hypsipyla Shoot Borer of the Meliacae, Kandy, Sri Lanka, 1996, ACIAR Proceedings No. 97 Canberra, 189 pp. Grijpma, P., 1976. Resistance of Meliaceae against the shoot borer Hypsipyla with particular reference to Toona ciliata M.J. Roem. Var australis (F.V. Muell) C.D.C. In: J. Burley and B. T. Styles (Eds.) Tropical trees: variation, breeding and conservation. Academic Press, London. pp. 69-78. Hall, J. B. and Swain, M. D., 1981. Distribution and ecology of vascular plants in a tropical rain forest, forest vegetation in Ghana. Dr. W. Junk Publisher London. Hartmann H.T., Kester, D.E. and Davies, F.T., 1997. Plant propagation: Principle and Practices. 6th edn. Prentice-Hall, London. Howard, F.W. Verkade S.D and Defilippis, J.V., 1990. Propagation of West Indies mahogany by cuttings. Turrialba 40:30-32. Hawthorne, W.D., 1990. Field guide to the forest trees of Ghana. Chatham: Natural Resources Institute, for the Overseas Development Administration, London. Ghana Forest Series 1, VI 278 pp. Husen, A. and Pal, M., 2006. Variation in shoot anatomy and rooting behaviour of stem cutting in relation to age of donor plants in teak (Tectona grandis Linn. F.). New Forests, 31:57-73. Irvine, F. R., 1961. Woody Plants of Ghana Oxford University Press, London.868 pp. Leakey, R.R.B. Chapman V.R. and Longman K.A., 1982. Physiological studies for tropical tree improvement and conservation. Some factors affecting root initiation in cuttings of Triplochiton Scleroxylon K.Schum. Forest Ecology and Management. 4: 53- 66. Leakey, R.R.B., 1990. Nauclea diderrichii: rooting of stem cuttings, clonal variation in shoot dominance, and branch plagiotropism. Trees, 4: 164-169. Leakey, R.R.B., Mesen J.F. Tchoundjeu Z., Logman K.A., Dick J.Mc.P. Newton A., Matin A., Grace J., Muron R.C. and Muthoka P.N., 1990. Low-technology techniques for the vegetative propagation of tropical trees. Commonwealth Forestry Review 69: 247-257. Limpiyaprapant, S., Soonhuae, P., and Kijka, S., 1996. Rooting ability of Khaya senegalensis cuttings in relation to hedge height and hormone application. Technical- Publication. ASEAN Forest Tree SEED Center Project. No. 33 12 pp. MacDonald, C., 1993. Practical woody plant propagation for nursery growers. Timber Press Inc. Portland, Oregon, USA. Maruyama, E. and Ishii, K., 1999. Somatic Embryogenesis in Big-leaf Mahogany (Swietenia macrophylla King) (S. M. Jain, P. K. Gupta, R. J. Newton eds) Somatic Embryogenesis in woody plants, 5:45-62. Mayhew, J.E. and Newton, A.C., 1998. The silviculture of mahogany. CABI Publishing, Wallingford, UK. 226 pp. Newton, A.C., Baker, P., Ramnarine, S., Mesen, J.F. and Leaky, R.R.B., 1993. The mahogany shoot-borer, prospects for control. Forest Ecology and Management 57:301-328. Newton, A.C., Leakey, R.R.B., Powell, K., Chelmen, K., Waugh, R., Tchoundien, Z., Mathies, P.J., Alderson, P.G., Messen, J.F., Baker, P., and Ramnarine, S., 1994. Domestication of mahoganies. In: R.R.B. Leakey and A.C. Newton (Eds.), Tropical Trees: The potential for domestication and the rebuilding of forest resources. HM 80, London, pp. 256-266. Nunes, E.D.C. Castilho, C.V.D., Moreno, F.N., Viana, A.M., 2002. In vitro culture of Cedrela fissilis Vellozo (Meliaceae). Plant Cell, Tissue and Organ Culture 7:259-268. Ofori, D.A., Newton, A.C., Leakey, R.R.B. and Grace, J., 1996. Vegetative propagation of Milicia excelsa by leafy stem cuttings: effect of auxin concentration, leaf area and rooting medium. Forest Ecology and Management 84:39-48. Ofori, D.A., Newton, A.C., Leakey, R.R.B. and Grace, J., 1997. Vegetative propagation of Milicia excelsa by rooting cuttings: Effects of maturation, coppicing, cutting length, and position on rooting ability. Journal of Tropical Forest Science 10: 115- 129. Opuni-Frimpong, E., 2000. Damage to growth and survival of native Meliaceae (African mahogany) by Hypsipyla robusta Moore (Lepidoptera:Pyralidae). M.Phil. thesis submitted to Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. 100 pp. Opuni-Frimpong, E., Karnosky, D.F., Andrew, J.A., and Cobbinah, J.R., 2005. Development of an integrated management strategy to reduce the impact of Hypsipyla species (Lepidoptera: Pyralidae) on African mahogany. The International Forestry Review 7:86 SAS Institute Inc., 2004. Qualification Tools User’s Guide, version 9.1.2 ed. SAS Institute, Inc., Cary, North Carolina, USA. Stenvall, N. Haapala, T. and Pulkkinen, P., 2004. Effect of genotype, age and treatment of stock plants on propagation of hybrid aspen (Populus tremula x Populus tremuloides) by root cuttings. Scandinavian Journal of Forests Research, 19:303-311. Swaine, M.D., Agyeman, V.K., Kyere, B., Orgle, T.K., Thompson, J. and Veenendaal, E.M., 1996. Ecology of forest trees in Ghana. ODA Forest Series No. 7. Taylor, C.J., 1960. Synecology and Silviculture in Ghana. Thomas Nelson and Sons Ltd. Edinburgh 417 pp. Tchoundjeu, Z. and Leakey, R.R.B., 1996. Vegetative propagation of African mahogany: effect of auxin, node position, leaf area and cutting length. New Forests 11:125-136. Tchoundjeu, Z., Avana, M.L, Leakey, R.R.B., Simons, A.J. Asaah, E., Duguma, B. and Bell, J.M., 2002. Vegetative propagation of Prunus Africana: effects of rooting medium, auxin concentrations and leaf area. Agroforestry Systems, 54: 183-192. Tchoundjeu, Z. and Leakey, R.R.B., 2000. Vegetative propagation of Khaya ivorensis (African mahogany): effect of stockplant flushing cycle, auxin and leaf area on carbohydrate and nutrient dynamics of cuttings. Journal of Tropical Forest Science, 12:77-91.

Major Research 7

Variation in wood properties (anatomy) in relation to Hypsipyla attack.

E. Ebanyenle, E. Opuni-Frimpong and J. K. Govina Forestry Research Institute of Ghana, UPO 63, KNUST, Kumasi-Ghana

Abstract

Recent studies to restore a valuable timber species, Khaya ivorensis in degraded forest through plantations have identified tolerant genotypes to shoot-borer attacks, encouraging plantation development. This paper examined the wood anatomical properties of naturally grown (escaped shoot-borer attack) and plantation grown K. ivorensis, which survived severe shoot-borer attack, aimed at predicting the wood quality. Results showed that, the wood anatomy of K. ivorensis from both sources were comparable. However, there were some observed differences in quantitative anatomical characters for wood of K. ivorensis the two forest types. Differences in the mean values of vessel, parenchyma and fiber proportions, were not statistically significant (P>0.05) except vessel proportion which exhibited significantly higher mean value for plantation than natural forest (P=0.05). In addition, the wood of K. ivorensis from natural forest exhibited significantly longer mean fiber length, thicker double fibre wall, narrower fiber lumen, and fiber diameter than the plantation forest. Thus, wood of K. ivorensis from natural forest is likely to exhibit relatively higher density than the plantation wood. However, the expected differences in strength properties between wood of K. ivorensis from natural and plantation based on the observed results would be relatively small to be considered significant for utilization purposes.

1.0 Introduction Khaya ivorensis is one of the valuable timbers in Ghana. However, sustainable supply is threatened due to over-exploitation. To curb this problem an attempt has been made to increase the resource base through plantation establishment. Unfortunately the Khaya ivorensis plantation efforts have been unsuccessful due to attack of the saplings by Hypsipyla robusta (mahogany shoot borer) which causes severe branching reducing the quality of timber and in worst cases killing the tree. Besides the difficulty in establishing plantations of mahogany due to Hypsipyla pest, timber merchants also have their reservations as to whether the quality of wood from plantations could retain all the qualities associated with mahogany wood from the natural forest.

In 1963, Forestry Research Institute of Ghana established 4 hectares of Khaya ivorensis which was abandoned due to severe H. robusta attack. However some trees of Khaya ivorensis survived the attack. Mahogany trees that are tolerant to Hypsipyla in plantations grow faster and could reach merchantable size far earlier than trees growing competitively in the natural stand (Opuni-Frimpong et al. 2008). It is reported in some species that fast growing trees have relatively lower quality of wood. In this investigation, comparative anatomical study of the wood of Khaya ivorensis from natural and the abandoned plantation was carried out to establish differences in their wood strength properties.

2.0 Applied methodology

Herbarium and wood samples (Fig. 1) of Khaya ivorensis were collected randomly from seven trees each from plantation and natural forests at breast height within the same size range, in the moist semi-deciduous forest types of Ghana for anatomical investigations. The diameter characteristics of the sampled trees are presented in Table 1 below:

Table 1: Mean diameter (cm) at breast height (DBH) of the sampled trees from natural and plantation forests.

Forest type Mean Minimum Maximum n Natural 85 61 118 7 Plantation 80 64 100 7

Strips were prepared from the wood samples collected from standing trees. A sub-sample each of 1.5 X 1.5 cm was taken from the sapwood and heartwood and used for anatomical studies (Fig. 1). Permanent slides of transverse sections of thickness 15-25μm were then prepared from these samples and observed under light microscope. Fiber, vessel and parenchyma proportions were determined from each sample using a 10x objective and 10x eyepiece with a dot grid scale of 20 points. Cell dimensions were determined from complete maceration of splits of matchstick. Fiber length, diameter, lumen and double wall thickness were measured on 100 complete and straight fibers per macerated sample. Terminology for description followed the recommendations of IAWA Committee (1989).

Figure 1: (a). Herbarium and wood sample of Khaya ivorensis. (b). Wood strip of K. ivorensis depicting sub-samples from sapwood (S) and heartwood (H) for anatomical studies.

Data analysis Analysis of results were done using GenStat statistical package. A t-test analysis was employed to determine the differences between the quantitative anatomical properties of Khaya ivorensis from plantation and natural forests.

3.0, 4.0 Presentation, Analysis and Interpretation of data and results

Results of the study indicate that, qualitatively the wood anatomy of Khaya ivorensis from plantation and natural (fig. 2) forests were comparable and similar to wood of Khaya ivorensis descriptions made by Panshin (1933) and Inside Wood (2007). However, there were some observed differences in quantitative anatomical characters for wood of Khaya ivorensis in natural and plantation forests as presented in Figures 3, 4 and 5. Although there were differences in the mean values of vessel, parenchyma and fiber proportions (Fig. 3), they were not statistically significant (>0.05) except vessel proportion which exhibited significantly higher mean value for plantation than natural forest (P=0.025). In addition, the wood of Khaya ivorensis from natural forest exhibited significantly longer mean fiber length, thicker double fibre wall, narrower fiber lumen, and fiber diameter than the plantation forest (Fig. 4 and 5). Opuni-Frimpong et at (2008) reported that the rate of growth of mahogany in plantations could be 400% faster than mahogany trees growing competitively under the natural forest canopy. It is possible that mahogany trees sampled from the natural forest were far older than the samples collected from the plantation though they were in the same size range. Recent investigation on some selected South Africa tree species showed that higher fiber proportion, lower vessel proportion, narrower fiber diameter and thicker fiber diameter are associated with higher density (Jackson, 2006).

Figure 2: Cross section of the wood of Khaya ivorensis. (a) Natural forest (b) Plantation forest. Scale bar=25μm

Implying that wood of Khaya ivorensis from natural forest is likely to exhibit relatively higher density than the plantation wood. The results therefore confirm the observation that natural trees produced better wood strength properties than plantation trees (Bosman and Bass, 1996; Bosman, 1997). However, the expected differences in strength properties between wood of Khaya ivorensis from natural and plantation based on the observed results would be relatively small to be considered as significant to any effect on utilisation purposes.

It is however recommended that further investigations be carried to establish the correlation between anatomical characters and strength properties for natural and plantation trees of Khaya ivorensis with similar diameter class to confirm or reject the current observation.

a a

a a

a b

Figure 3: A graph of vessel, parenchyma and fiber proportions of the wood Khaya ivorensis in relation to plantation and natural forests. Similar bars with same alphabetical letters in different forest type are not significantly different (p>0.05; n=70).

a b

a b

a b

Figure 4: A graph of fiber length of the wood of Khaya ivorensis in relation to natural and plantation forests. Similar bars with different alphabetical letters in different forest type are significantly different (p= 0.001; n=700).

a b

Figure 5: A graph of fiber length of the wood of Khaya ivorensis in relation to natural and plantation forest. Bars with different letters are significantly different (p=0.001; n=700)

5.0 Conclusions

The study showed that wood from trees in natural forest stands produced better wood strength properties than plantation trees. However, the differences in strength properties of the wood of Khaya ivorensis from natural forest and that from the plantation, is relatively small to be considered as significant to have any effect on its utilisation purposes.

6.0 Recommendation

It is recommended that further investigations be carried out to establish the correlation between anatomical characters and strength properties for natural and plantation trees of Khaya ivorensis as well as the other mahogany species, with similar diameter class to confirm or reject the current observation.

Bibliography

1. Bosman, M. T. M., 1996: Longitudinal variation in selected wood properties of naturally and plantation grown light meranti (Shorea leprosula and S. parvifolia, Diptercocarpaceae). IAWA Journal 17:5-14 2. Bosman, M. T. M. and P. Baas, 1996: Wood properties of naturally and plantation grown light red meranti. In: A. Schulte & D. Schone (eds.), Dipterocarp Forest Ecosystems: towards sustainable management: 578-590. World Scientific Publishing Co. Pte. Ltd., Singapore. 3. IAWA Committee, 1989: List of microscopic features for hardwood identification, IAWA Bull. n.s.10: pp.332 (1989) 4. Inside Wood, 2007. Khaya ivorensis, Published on the internet. http://insidewood/lib.ncsu.edu.search [accessed, 1 February, 2008]. 5. Opuni-Frimpong E., Karnosky D.F., Storer A.J., and Cobbinah J.R. 2008. Silvicultural systems for plantation mahogany in Africa: Influences of canopy-shade on tree growth and pest damage. Forest Ecology and Management, 255: 328-333. 6. Panshin, A. J., 1933: Comparative anatomy of the woods of the Meliaceae, sub- family Swietenioideae. Amer. J. Bot. 20: 638-668.

Major Research 8

Socio-economic studies for integrated Mahogany plantations with community farmers in Ghana

B. D. Obiri, E. Opuni-Frimpong and L. K. Ameyaw

1.0 INTRODUCTION

Mahogany is one of the prime tree species in Ghana in terms of merchantable timber and non-timber value particularly in the traditional herbal medicinal industry in Africa. A recent ethno botanical study identified the species as the most endangered from the perspective of the herbal industry in Ghana (Obiri et al., 2006); hence its conservation needs urgent attention. Declining stocks of Mahoganies in natural forest stands has necessitated its cultivation in plantations and integration into cropping systems as part of the research process to develop resistant strains of the species to the insect shoot borer attack. Moreover the socio- cultural and economic implications of plantation development in general and particularly that for stallholders in Ghana are quite unclear. Consequently, social and economic perspectives of integrating mahogany into production systems are necessary to complement biological mahogany research.

This report summarizes collaborative activities undertaken with three rural communities in 3 contrasting ecological zones i.e. forest-savanna transition, dry semi-deciduous forest and moist evergreen forest zones in Ghana from 2007 to 2009. The goal of this collaboration was to develop or experiment and promote integrated mahogany plantations with the communities to encourage its integration into production systems. This is to enhance its availability and to test the potential reduction of the incidence of the shoot borer in mixed cropping systems under smallholder conditions.

2.0 OBJECTIVE

The main objective of the entire study is to develop and promote integrated mahogany plantations with communities and assess the economics and sociological implications of Mahogany and smallholder plantation development in Ghana. Specific objectives are: 1. Establish integrated mahogany farm plantations with volunteer farmers in the Western and Brong Ahafo Regions of Ghana to develop and promote sustainable tree-crop farming 2. Comparative socio-economic analysis of 3 models/systems of plantation establishment with farmer communities in project areas 3. Evaluate the economic viability of smallholder plantations 4. Economic assessment of the basis for Mahogany research from the perspectives of the timber industry in Ghana

3.0 METHODS 3.1 Study sites

Three communities were selected for the socio-economic studies primarily based on their ecological differences and also disparity in approaches or institutional arrangements to smallholder plantation development. Figure 1, shows the ecological distribution of the sites in Ghana.

Nkranka

Tain II

Samartex-com

The main distinguishing features of the sites are as follows:

1. Nkranka, is a farming village in the Nkoranza District of the Bong Ahafo Region of Ghana. It is located in the forest-savanna transition zone. The collaboration involves community individuals planting the integrated plantations own their own farmlands the in off-reserve

2. Tain II –Berekumn site is located in the dry semi deciduous forest zone of the Brong Ahafo Region of Ghana. ABTS Company LTD, a timber firm is embarking on reforestation of degraded compartments in the Tain II forest reserve within its concession area in collaboration with farming communities fringing the reserve in a taungya system. The farmers have free land for the first four years of plantation establishment to cultivate food crops including cassava and plantain. ABTS supplies tree seedlings to farmers for planting and nurturing while tending their food crops and pays for farmer labour. New plots are allocated to farmers after the 4 years under the same arrangements. Farmers have no share in future tree proceeds.

3. Samartex Extension communities are located in the Wassa Amenfi District of the Western Region of Ghana in the Wet Evergree Forest Zone. This model involves community individuals of farmers establishing farm plantations on their own lands in the off-reserve areas of Samartex Timber & Plywood Co. Ltd’s concession in the Wassa Amenfi District. The company’s aim is to ensure the availability of timber for processing by the company while improving local livelihoods and contributing to biodiversity and environmental sustainability. The company is assisting farmers with planting materials and technical assistance in an extension programme to establish their farm plantations. The tree farms are designed as multi-strata tree-crop systems comprising long, medium and short term components. Samartex has the first option to purchase the timber at the end of the rotation.

3.2 Collaboration/participatory action research Participatory techniques mainly informal discussions were employed in interacting with village elders and community members in selected villages to introduce the project, establish rapport, enroll farmers and plan for plantations to be planted. Field visits were undertaken to establish and monitor plantations with farmers. Both biological and socio-economic data were collected.

3.3 Production and supply of planting material

At Nkranka seedlings were produced and managed in a nursery at a suitable site designated by the farmers in the community to ensure early supply and availability of seedlings for planting. This was also to build local capacity in tree nursery production. The project supported the nursery activities financially by engaging paid labor, which is one of the community members as a caretaker. At Tain II and Samareboi, the communities were already organized under ABTS LTD taungya and Samatex extension services. The project supplied seeds to ABTS and Samatex for nursery production and distribution to farmers

3.4 Establishment and management of smallholder plantations Field preparation

To ensure that fields to be used for planting were suitable for the purpose, field visits were first made to proposed farm sites to access their suitability. The fields were prepared and farmers assisted to peg their plots for tree positions at 3 x3 triangular spacing. This was done for Nkranka and Samaetex communities

Field Establishment

The following considerations were discussed with farmers particularly at Nkranka to ensure that farmers are able to manage their fields properly to facilitate the attainment of project objectives as well as data collection for scientific analysis. It was agreed that during the first year of establishment each farmer plot will be approximately 1 acre (0.4 ha) in size. A standard design for inter-planting the trees on farms was adopted to minimize errors. A randomized complete block design was assumed with 4 blocks or sub plots per farmer plot as the replicates. Trees were planted at a spacing of 3x3m. The number of each species planted per sub plot was in accordance to the quantity produced in the nursery at the time of transplanting in 2007, i.e. K. Anthotheca (25), E.utile (8) C. odorata (15) and T. ivorensis (5) (Figure 1) but approximates to 530 trees per ha. Food crops (maize, cassava, yam, groundnut, okro, etc.). Farmers will secure pegs and researchers assist with techniques for pegging tree positions and planting of tree seedlings. Figure 2 illustrates the layout of farmer plots at Nkranka

25 - K. anthothec 25 - K. antho 15 – C. odorata 25 - K. anthothe 15 – C. odor 8 – E. utile 15 – C. odorata 25 - K. anthotheca 63.3 8 – E. utile 5 - T. ivorensis 8 – E. utile 15 – C. odorata 5 - T. ivoren 5 - T. ivorensis 8 – E. utile 5 - T. ivorensis

63.3 Figure 2: Farmer plot design and tree-mix at Nkranka

Field Monitoring and assessment

Farmer fields were periodically visited to assess general conditions and collect data on tree survival, growth i.e. height and diameter measurements and any constraints concerning management of the fields for redress. Information on farmers and their plot characteristics was collected during the first of these visits after planting.

3.5 Data collection and analysis Structured questionnaires were designed to gather the relevant information from farmers and timber industry. The data was analyzed with Microsoft SPSS and Excel. Data on farmer and their plot characteristics, their perceptions on involvement in the plantation development and tree growth were collected. For the economic analysis of the smallholder plantations, input costs and food crop yields were estimated at prevailing local market rates. Merchantable timber yield at 40 years were estimated from yield tables and growth models. Stumpage price per cubic meter of timber was obtained from TIDD, Forestry Commission. Economic thinning during a 40 year rotation was assumed. This is because the tree mixture comprises of 4 different speceis, hence sequential harvesting of the speceis at diffreent times at their respective rotations generated income prior to end of the rotation. Teak is harvested at 50% in year 20 and 25 for timber. Cedrella is also harvested at 50% at year 25 and 30 for timber while T. Superba, T. ivorensis and Khaya speceis are harvested at the end of the rotation at year 40. Economic indicators estimated at 10% discount rate were Benefit cost Ratio (BCR), Net Present Value (NPV) and Internal Rate of Return (IRR).

4.0 RESULTS AND DISCUSSION

4.1 Farmers, their plots characteristics and perceptions

Table 1: Farmer and plot characteristics

Characteristics Nkranka Tain II- Berekum Samartex (ABTS ) No. fields 15 12 12 Field size per farmer 0.98 (acre) average 1.95 acre average (1-3 7.46 acre average (0.75-1.0 acre) acre) Total acreage 14.75 acres (5.9ha) 21.5 acres(8.6ha) - Land ownership 100% landowners Taungya tenants Taungya tenants Gender % 67 Men 17 Men 83 Men 33 women 83 Women 17 Women Tree species Khaya anthotheca, Cedrella odorata, Khaya Entandrophragma utile, Tectona grandis, Khaya grandifoliola, Cedrella odorata and spp, Terminali spp. Khaya ivorensis, Terminalia ivorensis Entandrophragma angolense, Entandrophragma utile, others Food intercrops Maize, cassava, Plantain, cocoyam, Maize, Plantain, groundnuts, yams, cowpea cassava, maize, vegetables cassava, yam, cocoyam, vegetables

4.1.1 NKranka

The average age of respondents was 53 with males forming 64% of respondents and the remaining 36% being females. Four tree species (Khaya anthotheca, Entandrophragma utile, Cedrella odorata and Terminalia ivorensis) have been planted on 14.75 acres of land. Crops cultivated were Maize, cassava, groundnuts, yams, and cowpea.

All 15 farmers involved in the project, agreed that they had problems with regards to erratic rainfall patterns, weeds, low soil fertility, lack of incentives, stunted growth of trees in some cases, forking and expensive maintenance costs. They however added that the project is generally going well with both trees and crops growing substantially. Both natives (85%) and settlers (15%) mentioned the project being lucrative, declining tree stocks, climate change and future investment as parameters that motivated them to join the project. For the success of the project, respondents suggested more trees be planted, change in some low fertility sites, as well as incentives in both cash and kind from the project.

4.1.2 Tain II-Berekum (ABTS) The ABTS plantation initiative has so far had a very impressive enrollment according to site inspections and survey results. However, quantitative information was gathered from twelve taungya farmers of which females formed 83%. The natives of the area formed 90% of the farmers. The average age of respondents was 47. Personal interest, accessibility to fertile lands for farming and advice from friends was the principal reasons that motivated the farmers into the taungya agreement with ABTS limited for establishing the plantations.

Four tree species (Cedrella odorata, Tectona grandis, Khaya spp., Terminalia spp.) have been planted on 21.5 acres of land. Crops cultivated were plantain, maize, cocoyam, yam, cassava, tomatoes and pepper. Respondents mentioned lack of incentives like hoes and cutlasses, transportation, weeds among others as some of the problems they faced and suggested that ABTS improve the already existing lackluster transportation they provide to the plantation area, occasional allowances and provision of farming implements to facilitate work on their tree farms.

4.1.3 Samartex extension villages

Several farmers are involved in this extension programme. However, a sample of 12 farmers was interviewed for their perceptions and performance of their fields. Males formed 83% and females 17%. Natives also formed 92% of respondents and settlers 8%. The average age of the farmers was 55. Four tree species (Khaya grandifoliola, Khaya ivorensis, Entandrophragma angolense, and Entandrophragma utile) and other species have been planted. Pest attacks, weeds, expensive labour, perceived long payback period, marketing problems for intermediate crops, expensive tree maintenance practices and lack of incentives were some of the problems respondents mentioned. Respondents also suggested that SAMARTEX should provide them with incentives like boots and cutlasses and help them market their food crops and create alternative livelihood activities as well. Despite these problems farmers were initially motivated to engage in establishing tree farms due to the declining tree stocks in the area. They also perceived these farms as legacies for their children and the unborn descendants. Crops inter planted with the trees included maize, plantain, cassava, yam, cocoyam, vegetables and in some cases oil palm and cocoa.

4.2. Plot performance

Generally tree survival was very good on most fields with over 80% survival being recorded. The general conditions were also good as weed growth was average to minimum on most fields. The major practical constraint encountered by farmers is inadequate labour to effectively control weeds and enhance tree growth after food crops have been harvested.

4.3. Tree growth

The farmer plots were established at the same time periods in the growing season in 2007. However, better growth conditions with respect to soils (soils from degraded forest reserve) and rainfall (>1200mm per annum) at the dry semi-deciduous zone in Berekum may have accounted for the higher growth in diameter and height at this site. The Nkranka fields were farmlands that were being cropped, hence had possibly declined in fertility. Moreover rainfall at the Nkranka areas is 1100mm per annum or less. Nonetheless, trends in growth of 4 key species indicate that Cedrella grows fastest in both the transition (Nkranka) and dry semi- deciduous forest zones (ABTS Tain-II), Figure 3. Data from Tectona grandis (teak) is not presented in the ABTS chart.

Figure 3: Growth in diameter and height of key species in the mixture on farm plots

4.5 Economic analysis: Ex-ante profitability assessment

Table 2: Discounted cash flow indicating profitability of the integrated mahogany plantation

Profitability indicator Value/ha Nkranka ABTS Tain-II B/C ratio 10 6.8 NPV (GH¢) 21,184.0 22,359.0 IRR (%) 25 20

Table 2 indicates that the smallholder integrated mahogany plantations are economically viable at 10% discount rate. As the BCR is > 1, NPV is positive and IRR is > 10%. The sensitivity analyses also show that even at the worst case scenario, i.e. 50% decrease in timber yield & 50% increase in total costs, these plantations are profitable.

Several assumptions were made in this analysis. For instance although growth was better at ABTS Tain II than at Nkranka, merchantable tree volume were estimated from known convectional figures from yield tables, hence tree volume at the periods of harvest were assume to be the same for the different species for both sites. It was also observed that earlier income streams from shorter rotation tree species in the mixture increases profitability. It must be noted that the mixture at ABTS had 5 tree species and more food crops compared with 4 tree species at Nkranka and fewer food crops. It is not clear from this analysis if this has influenced the values for the Benefit-Cost Ratio and IRR. But the result seems to suggest that profitability may decline with increase in complexity of the mixture.

5.0 CONCLUSIONS & RECOMMEDATIONS

The collaboration with farm communities and the timber industry was quite eventful and encouraging particularly the strategy of engaging farmers to produce future industry timber needs on their farmlands in the off-reserve areas. This is commendable because much of timber in Ghana was harvested from farmlands in the past.

Preliminary financial analysis of smallholder integrated mahogany plantation in Kranka community farms and Socio economic analysis of the ABTS Taungya Plantations were conducted. The analysis shows that the smallholder integrated mahogany plantation with Kranka farmers is profitable at 10% discount rate and stable to downward changes in cost and yield factors up to 50%. However, farmers often desire to plant fast growing tree species and those that yield early returns, thus are often not willing to invest in plantations with trees of very long gestation periods even when they have adequate land resources. Hence manipulation of the system to generate interim benefits to the farmer is essential particularly for household cash needs and maintenance of the plantation over the years. This is important because after the initial benefits from food crop harvests in the first few years (3-4 years) in the establishment phase of the plantation, farmers may have to wait for long periods till the tree matures to be harvested for timber. The potential for the farmer to source addition income through carbon credit for the carbon dioxide that their trees sequester will be look at in the next phase of the project.

Obviously there is need to establish the optimum number of trees and food crops required in the mixture for optimum profit. Also, the objective 4 of the socio-economic studies has not been completed and needs to be done during the next phase of the project.

6.0 IMPLICATIONS FOR PRACTICE One key lesson from this aspect of the project is that more of farmer collaborative farm plantations must be promoted at all levels within designated degraded reserves and off- reserve areas on farmlands. Encouraging individually owned farmer plots converted to farm plantations will obviously diversify farm income sources, provides security to poor farm households and promotes environmental sustainability. The institutional arrangements with private timber firms that guarantee market for tree produce will make such initiatives attractive for investment by smallholders, particularly for multi-strata mixtures with fast growing species providing income in the short, medium and long terms. It is also suggested that there is the need to explore the possibility of developing project design documents for the small holder farmers to look for carbon credits for the carbon that their trees will sequester.

REFERENCES

Elevitch, C. R. & Wilkinson, K. M. 2000 .Economics of Farm Forestry: Financial evaluation For Landowners. Agroforstry guides for Pacific Islands, No. 7. Permanent Agricultural Resources, Holualoa, Hawaii, USA. www.agroforestry.net

Forest Inventory Project (FIP) (1989). General yield tables for Ghana. In: Seminar proceedings pp 50–52, 29–30 March 1989 Accra Gittinger, J.P., 1982 Economic analysis of Agricultural Projects. 2nd ed. M. Yamada and H.L. Gholz, 2002. Growth and yield of some indigenous trees in an Amazonian agroforestry system: a rural-history-based analysis. Agroforestry Systems 55: 17–26, 2002.

Obiri, B. D., Ofori, D. A. and Gyimah, A. 2006. Ethno Botanical Survey of Medicinal Plants in Ghana. Progress Report. Afornet Ethno botany Project, FORIG.

Samartex 2005. The Oda-Kotoamso Community Agroforestry Project (OCAP) www.samartex.com

Timber Industry Development Division (TIDD), 2008. Stumpage prices for commercial timber species in Ghana. TIDD, Forestry Commission, Ghana.

World Bank, 1996 Handbook on economic analysis of investment operations. OPR, No. 20733.