Available online at http://ajol.info/index.php/ijbcs

Int. J. Biol. Chem. Sci. 3(5): 1057-1064, October 2009

ISSN 1991-8631

Original Paper http://indexmedicus.afro.who.int

Autoecological study of Ricinodendron heudelotii (Baill) Pierre et Pax. in Agulli forest

G. M. ANJAH 1* and M. B. OYUN 2

1 Department of Biology, University of Dschang, . 2 Department of Forestry, University of Akure, . * Corresponding author, E-mail: [email protected]

ABSTRACT

Autoecology seeks to explain how, or to what extent species are regulated in nature, why some are common, others, rare, and why some remain relatively rare over many consecutive generations. Timber and non-timber resources have suffered serious decline due to unregulated exploitation. More than 11million hectares of mature tropical forest are converted into agricultural, pasturelands, and other land uses every year threatening the existence of species of ethnoforestry importance such as Ricinodendron heudelotii. Two sites of land were demarcated in Agulli Forest Reserve, Division of Cameroon. Each site had 20 subplots of 20 m x 25 m, mapped out systematically. This study aimed to investigate the stem density (D), frequency (F), cover (C), and the regeneration potential (RP) of Ricinodendron heudelotii. The t-test was carried out to determine the differences for independent variables of each site. D, F, C and RP for Ricinodendron tree stands at both sites were not significantly (p>0.05) different. © 2009 International Formulae Group. All rights reserved.

Keywords: Autoecology, Ricinodendron, regeneration potential, ethnoforestry, status.

INTRODUCTION secondary forests, common throughout the The importance of the forest and its semi-dry, wooded savannah zone, where it is product to the well being of the adjoining scattered in gaps at forest edges and in communities cannot be overemphasized. secondary scrub and thickets (ICRAF, 2004) However, most natural forests which are the due to forest fragmentation. In Cameroon, it primary sources of these products have either grows in secondary forests (Vivien and Faure, been completely lost or seriously degraded. 1985) at altitudes ranging from 130 to 1030m There is an urgent need to protect the above sea level (Fondoun et al., 1998). It is remaining forests and to preserve the distributed especially in the forest zone traditional knowledge associated with their (Southern Cameroon), excepting mountain uses (Okafor and Hamm, 1999). forests. In the Northwest Region of Yandji (1999) defined NWFPs as all Cameroon, it is found in the Menchum River the resources or products derived from forests Valley area (pers. Comm.). except wood. However, identification of these Ricinodendron heudelotii belongs to products is based on the part of the tree being the family (Vivien and Faure, used. Tchoudjeu and Atangana (2006) 1985; Tchoudjeu and Atangana, 2006). It is a identified Ricinodendron heudelotii as a large deciduous tree reaching 45 m high and NWFP. It is found in central, western and 1.5 m in diameter. The crown is spherical, southern , occurring typically as a with much branched verticillate and horizontal species of the fringing, deciduous and branches (Souane, 1985). The bole is often

© 2009 International Formulae Group. All rights reserved.

G. M. ANJAH and M. B. OYUN / Int. J. Biol. Chem. Sci. 3(5): 1057-1064, 2009 straight, sometimes sinuous or twisted, 2005) and a degree of crude processing by cylindrical, enlarged and sometimes farmers to produce edible oil used in the channelled at the base (Shiembo et al., 1997). manufacture of soap and varnish (Ekam, A socio-economic survey by Foundon 2003). The iodine and saponification values et al. (1999) reveals that this plant species is also point to the potential of the oil in paint put into four main usage categories which are and cosmetics. consumption, medicinal, sociocultural and soil Most of the studies on Ricinodendron fertility improvement. For consumption, are based on the major production areas Shiembo (1994) reports that the cotyledons (Ndoye et al., 1998; Tchoundjeu and are sought-after as ingredients for soups and Atangana, 2006). Fondoun et al. (1999) used to supplement a wide variety of dishes. adopted the use of questionnaires in their As a medicinal commodity, the bark, roots inventory in the open areas of southern and leaves are extracted and steeped overnight Cameroon. Little is known on the ecological in boiled water resulting in a yellow decant status in some production areas of savannah which if consumed as an infusion, can cure regions notably Agulli forest reserve in the stomach pains, , or to ease delivery for Menchum Valley subdivision of Cameroon. R. pregnant women (Fondoun et al., 1999). The heudelotii, just like other species in Agulli and bark is also used to treat elephantiasis while other secondary forests in Cameroon, is the dried bark is used to ferment palm wine becoming endangered (pers. Comm.; and the latex and leaves used as purgatives Tchoudjeu and Atangana, 2006). The stands (Abbiw, 1990). The socio-cultural use of this within the forest are declining; those in the tree is at the level of the dried stony seeds in open areas of villages are not fruiting (pers. many traditional games such as the local comm.) thus, heightening the fear of its ‘drou’ game commonly called “songho”, and extinction and making pertinent its at the level of its wood which is carved into conservation. There are no strategies set for antiquities and drums (Shiembo, 1994). Most any in situ and ex situ improvement of this farmers intentionally leave or spare this tree species in this community. Sustainable on their cocoa plantations as well as on management options for this species are cocoyam and plantain farms as a shade tree necessary so as to curb over-exploitation and also for soil fertility improvement. Most leading to extinction. farmers indicated that cocoyam It is thus in this light that investigations (Xanthosomonas sp.) and plantain (Musa sp) on some autoecological parameters such as cropped in the vicinity of Ricinodendron trees the stem density (D), frequency (F), Cover give better yields (Fondoun et al., 1999). The (C), and the Regeneration Potentials for R. large crowns of njangsang trees protect soils heudelotii were carried out in Agulli Forest and crops from the sun, pounding rains and Reserve. strong winds, especially in savannah zones (Anigbogu, 1996). MATERIALS AND METHODS The cotyledons of Ricinodendron Study area commonly called njangsang are a major Figure 1 shows the distribution of R. source of income not only at the local and heudelotii in Cameroon. This study was national levels but also at the international limited to the Wum forest of Menchum level where it acts as foreign exchange earner Division found in the Northwest Region of to Cameroon and other neighbouring countries Cameroon. This division has its headquarter in in Central African States. Ndoye et al. (1998) Wum, which is 77 km from , the observed that in the humid zone of Cameroon, headquarter of the Northwest Region the sale of NWFPs like Dacryodes edulis, (Ministry of Forestry and Wildlife, 1999) and Irvingia sp, Cola acuminata and has several village communities some of Ricinodendron heudelotii amounted to at least which lie along a river valley. $1.75 million in the first half of 1995. They This River Valley Community shares also observed that more than 1,100 traders boundaries with Wum Central Subdivision to mainly women were engaged in the the North, Akwaya Subdivision to the distribution of these products. The cotyledons Southwest, the Federal Republic of Nigeria to are processed in laboratories (Tchiegang et al., 1058 G. M. ANJAH and M. B. OYUN / Int. J. Biol. Chem. Sci. 3(5): 1057-1064, 2009

Figure 1: A map showing the distribution of R. heudelotii in Cameroon.

the West, Njikwa Subdivision to the South with notably Agulli, and Bu. The forest edge and the Bafut Subdivision to the East. It lies of Agulli is bordered by vast acres of rice between longitude 9°10’ and 10°20’ East and farms and human settlements. The mean latitude 6°10’ and 6°31’ North (MINFOWI, annual temperature is between 17.6 ºC and 1999). Some villages found this river valley 30.5 ºC, while the total annual rainfall per include Befang (700 m.a.s.l), Agulli (700 year is about 2,043.7 mm (IRAD, 1988). m.a.s.l), Modele (400 m.a.s.l), Benakuma, Mukurou, Beba and Okoromanjang. Site preparation This Wum forest is about 89.24 ha Two major plots were demarcated for (MINFOWI, 2003) and shares its boundaries this study. One hectare each of 100 x 100 m 1059 G. M. ANJAH and M. B. OYUN / Int. J. Biol. Chem. Sci. 3(5): 1057-1064, 2009 was mapped out at the edge and interior of other growth stages indicate a low and Agulli forest. The major plot at the edge was insignificant regeneration potential (Udah, demarcated along the rice farms and forest 1995). The alternative hypothesis was that trees mosaic while demarcation of the major regeneration potential was significant if there plot in the interior was further into the forest, were a lower number of seedlings. about 1 km away from the first plot. Each of The size classes were as follows: these was later subdivided into 20 minor plots Class 1 ------10 to 50cm, of 20 m x 25 m. From the major plots, all the Class 2 ------51 to 100 cm, trees having girths or circumferences of 30 cm Class 3 ------101 to 150cm, and above at diameter at breast height were Class 4 ------151 to 200cm, measured using a tape calibrated in cm. This Class 5 ------201 to >250cm. data was used to calculate the following parameters in the minor plots; Data analysis (i) The Density of Ricinodendron Data collected for the density and cover heudelotii, were analyzed respectively by t-test for (ii) The Frequency, independent samples to compare any (iii) The Relative Cover, and differences between major plots 1 and 2. (iv) The Regeneration potential. Histograms were drawn using the frequency Density values obtained to compare relative frequency This was taken to be the number of values of Ricinodendron trees at the edge and Ricinodendron trees per hectare (Barbour et the interior major plots. The t-test was also al., 1987). The number of trees were counted used to analyze the data for regeneration for each minor plot and recorded, giving the potential in order to determine any differences data for 20 minor plots respectively. This data in the regeneration potentials of was used to calculate the relative density of Ricinodendron in major plots 1 and 2. this species for each major plot using Colinvaux (1986) formula respectively. RESULTS Frequency Density This was determined by assessing the The values for the Relative Density of number of minor plots containing Ricinodendron heudelotii at the edge and Ricinodendron trees for each hectare interior were; 19.7% and 15.6% respectively (Chapman and Reiss, 1995) and converted to (Table 1). The t-test for the independent percentages to get the relative values for each variables showed that there were no major plot. significant differences (t = 5055; df = 38) in Relative cover the density values between the major plot 1 at This was determined by using a the edge and major plot 2 in the interior at calibrated tape and measuring the p>0.05. circumferences of each stem of Ricinodendron present in each minor plot and converting Frequency these values to percentages to obtain the Species frequency of Ricinodendron relative values per major plot (Collinvaux, heudelotii for the edge was 15% and for the 1986). interior, 10%. Relative frequency was 1.22% Regeneration potential for plot 1 and 0.44% for plot 2. In this study the regeneration potential Figure 2 shows the histogram for the relative was assessed based on the size classes of the frequency for plots 1 and 2. Ricinodendron trees. The twenty minor plots of each major plot were used. The minor plots Relative cover with Ricinodendron trees were noted. The Table 2 shows the Relative Cover circumferences at breast height of each tree values for edge and interior major plots. The t- were measured and recorded under respective test analysis indicated that there were no size classes based on Igor et al. (2000) model. significant differences (t = 14; df = 38) for The null hypothesis considered was that a Relative Cover among the independent higher number of seedlings with respect to the samples at p >0.05. 1060 G. M. ANJAH and M. B. OYUN / Int. J. Biol. Chem. Sci. 3(5): 1057-1064, 2009

Table 1: Density values of R. heudelotii for Regeneration of R. heudelotii in Agulli egde and interior of forest (trees per hectare). forest Studies on regeneration potentials of Quadrates 1 (edge) 2 (interior) Ricinodendron showed that there were no 1 0 0 seedlings, no saplings, 1 pole, and 2 mature 2 0 0 trees at the edge; while in the interior, there 3 7.0 0 were no seedlings, no saplings, no poles but 2 4 0 0 mature trees (Table 3). 5 7.0 0 The t-test reveals that there were no 6 0 0 significant differences (t = 0.361; df = 6) 7 0 0 between the two plots at p>0.05. 8 0 0 9 0 0 DISCUSSION 10 0 0 Considering human interferences at the 11 0 0 edge of Agulli owing to cultivation of rice, 12 0 0 one would have expected parameters of plot 1 13 0 0 to be significantly lower than those of plot 2. 14 0 4.0 Also, owing to the fact that most or almost all 15 0 5.0 the fruits are picked up at time of harvest 16 0 0 within plot 1 relative to plot 2 which is further 17 0 0 away from immediate human influence, one 18 6.0 5.0 would have observed these values to differ 19 0 0 with density, frequency, cover and 20 0 0 regeneration potential, higher in the interior. * t-test for independent samples indicate no significant It can however be deduced that difference at p>0.05. environmental factors such as more light at

the forest edge and a lesser intensity and Table 2: Cover values of R. heudelotii for quality in the interior could influence these edge and interior of forest (trees per hectare). insignificant values (Nwoboshi, 1982). It can thus be assumed that, R. heudeloti, being a Quadrats 1 (edge) 2 (interior) heliophyte growing in secondary forest 1 0 0 (Doucet and Koufani, 1997; Ayuk et al., 1999; 2 0 0 Fondoun et al., 1999; Tchoudjeu and 3 21.0 0 Atangana, 2006), would have significantly 4 0 0 higher values in plot 1 than in plot 2. This was 5 5.0 0 not the case, as evidenced by no significant 6 0 0 differences between the two in their D, F, C, 7 0 0 and RP values. It was also expected that 8 0 0 because of more light at the forest edge, more 9 0 0 saplings, poles, and mature of R. heudelotii 10 0 0 would be available, and more seedling buried 11 0 0 in the understory, in the interior. This was not 12 0 0 the case. 13 0 0 Thus going by the assessment of Udah 14 0 10.0 (1995) that a higher proportion of seedlings 15 0 15.0 compared to the other developmental stages of 16 0 0 trees indicate a low and insignificant 17 0 0 regeneration potential for a species, and vice- 18 14.0 11.0 versa, we can thus reject the null hypothesis in 19 0 0 Agulli forest because there were no significant 20 0 0 differences. Most of the stands found were * t-test for independent samples indicate no significant mostly mature trees indicating that the differences at p>0.05. regeneration potential is high.

1061 G. M. ANJAH and M. B. OYUN / Int. J. Biol. Chem. Sci. 3(5): 1057-1064, 2009

1,4

1,2

y 1 c n e u y q c e n r f e 0,8 u e q v e i r t F a l e e v i R t 0,6

a

l

e

R

0,4

0,2

0 Forest edge Forest Interior Forest Portion

Figure 2: Frequency of R. heudelotii in forest edge and interior.

Table 3: Size class distribution of Ricinodendron trees in major plots 1 (edge) and 2 (interior).

Size-class 10 – 50 cm 51 – 100 cm 101–150 cm 151– 200 cm ≥ 201 cm 1 0 1 1 1 1 2 0 0 0 0 3 t-test for independent samples indicate no significant differences at p>0.05.

Van (1997) reported abundant non-interference producing higher values in regeneration of R. heudelotii after logging in the interior, it will thus imply that appropriate Southern Cameroon. Van’s report infers that silvicultural systems be implemented for the logging creates a removal of canopy; thus propagation of Ricinodendron in this forest. more light penetrating the undergrowth which Regeneration systems such as Enrichment agrees with Luken et al. (1997) on the positive Planting and Clearfelling can be options since response of understory species to gap logging improved this process in southern formation and soil disturbances. Similarly, Cameroon (Van, 1997). If not successful, Cintra and Horna (1997), observed a higher alternative methods rather than natural proportion of seedling understorey growth in regeneration in the natural habitat to gaps created in the shaded understory of the propagate R. heudelotii in the wild have to be Amazonian forest. sought to ensure the survival of this important Thus, if light did not produce tree species in this community. significant effect on Agulli forest edge, nor 1062 G. M. ANJAH and M. B. OYUN / Int. J. Biol. Chem. Sci. 3(5): 1057-1064, 2009

Bringing the species out of the lisation, et Gestion Durable. Projet secondary forest to cropping land or « Mise en place de forts communautaires homestead will necessitate studying the en peripherie de la Reserve Faune du Dja appropriate ex situ conditions under which Cameroun »; 71p. this can be achieved (Reeds, 1999). Such Ekam VS. 2003. Evaluation and studies would include factors for breaking characterization of the seed oils of dormancy, the growing medium for Trichosanthes cucumerina (snake gourd) germination, the specific light conditions, and Ricinodendron heudelotii (honey nutrient requirements, storage conditions of plum).” Global Journal of Pure and seeds, sowing or burial depths of seeds and Applied Sciences, 9(2): 217-220. the use of vegetative propagation technique as Fondoun JM, Manga TT, Kengue J. 1999. an alternative to the use of seeds and thus Ricinodendron heudelotii (njangsang). giving us a clue to its coppicing potentials for Ethnobotany and importance for forest clonal forestry. dwellers in Southern Cameroon. Plant- Genetic-Resources Newsletter, 118: 1-6: REFERENCES 12ref. Abbiw DK. 1990. The Useful of ICRAF. 2004. http://www.worldagroforestry. . In West African Uses of Wild and o rg/Sites/TreeDBS/aft/speciesPrinter Cultivated Plants. Intermediate Friendly.asp?Id=1449 Technology Publications and the Royal Igor D, David FR, David L. 2000. Ecological Botanic Gardens: Kew; 152-157. processes maintaining differential tree Anigbogu NM. 1996. Nature’s gifts: species distributions in an Australian improving trees and shrubs around the subtropical rain forest: Implications for world. Ricinodendron heudelotii in models of species coexistence. Jour. Nigeria. Agroforestry Today, 8: 18. Trop. Ecol., 16: 387-415. Ayuk ET, Duguma B, Franzel S, Kengue J, IRAD. 1989. Report of activities for the Mollet M, Tiki-Manga T, Zenkeng P. 1988/1989 year. Menchum Division. 1999. Uses, management and economic Ministry of Scientific Research, potentials of Garcinia kola and Cameroon. Ricinodendron heudelotii in the humid Luken JO, Kuddes LM, Tholemeier TC. 1997. lowlands of Cameroon. Journal of Response of understory species to gap Tropical Forest Sciences, 11(4): 740-761. formation and soil disturbance in Barbour MG, Burk JH, Pitts WD. 1987. Lonicera maackii thickets. Restoration Methods of sampling forest communities. Ecology, 5(3): 229-235. In Terrestrial Plant Ecology. Benjamin / Ndoye O, Perez MR, Eyebe A. 1998. The Cummings Publishing company, Inc.: markets of non-timber-forest-products in California, U.S.A.; 182-208. the humid forest zone of Cameroon. Chapman JL, Reiss MJ. 1995. Autecology. In Network paper, Rural Development Ecology, Principles and Applications. Forestry Network. No. 22c, 20p. Cambridge University Press: Cambridge; Okafor J, Ham R. 1999. Identification, 3-4. utilization and conversation of medicinal Cintra R, Horna V. 1997. Seed and seedling plants in south-eastern Nigeria. In Issues survival of the palm (Astrocaryum in African Biodiversity. Washington, DC, murumuru) and the legume tree (Dipteryx BSP. 3; 1-7. micrantha) in gaps in Amazonian forest. Reed F. 1999. Enlightened forest Journal of Trop. Ecol., 13(2): 257-277. management. Forest Ecology and Collinvaux PA. 1986. Populations and Management, 115: 135-146. species. In Ecology, Principles and Shiembo PN. 1994. Domestication of Applications. John Wiley and Sons, Inc.: multipurpose tropical plants with U. S. A.; 134-172. particular reference to Irvingia Doucet JL, Koufani A. 1997. Etude des gabonensis Baill, Ricinodendron produits secondaires vgtaux de la fort heudelotii (Baill) Pierre et Pax and de Kompin, Cameroun. In Utilizations, Gnetum africanum Welw. PhD Thesis, Inventaires, Regeneration, Commercia- University of Edinburgh.

106 3 G. M. ANJAH and M. B. OYUN / Int. J. Biol. Chem. Sci. 3(5): 1057-1064, 2009

Shiembo PN, Newton AC, Leakey RRB. Department of Forest Resources 1997. Vegetative Propagation of management. University of Ibadan, Ricinodendron heudelotii, a West African Nigeria. (Unpublished). Fruit Tree. Journal of Tropical Forest Van DJ. 1997. Assessment of Non-Timber- Science, 9(4): 514-525. Products-Resources in view of the Souane. 1985. Manual of Dendrology, development of sustainable commercial Cameroon. Group Poulin, Theriaultltee. extraction. The Netherlands: Department 3350 Boul, Wilfrid, Hamel: Quebec, of Forestry, Wageningen Agricultural Canada. University, 13p. Tchoundjeu Z, Atangana AR. 2006. Vivien J, Faure JJ. 1985. Arbres Forêts Ricinodendron heudelotii (Baill.) Denses d’Afrique Centrale. Agence de Southampton Centre for Underutilized Coopération Culturelle et Technique: Crops. University of Southampton: Paris, France; 209p. Southampton, UK; 74p. Yandji E. 1999. Gestion durable des produits Udah CA. 1995. Ecology of some medicinal forestiers non ligneux. Paper presented at woody plants in Nigeria, the seminar FORAFRI de Libreville Gabon, Zanthoxylum (Fagara) Linn. Ph.D. thesis. 10p.

106 4