Rehabilitation of Degraded Lands in Misiones, Argentina

BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) 51 RÉHABILITATION DE SOLS / LE POINT SUR…

Rehabilitation of degraded lands in Misiones, Florencia Montagnini1 Beatriz Eibl2 Argentina Roberto Fernández3

1 Yale University School of Forestry and Environmental Studies 370 Prospect Street New Haven, CT 06511 USA

2 Facultad de Ciencias Forestales Universidad Nacional de Misiones (3382) Eldorado, Misiones Argentina

3 INTA EEA Monte Carlo (3384) Monte Carlo, Misiones Argentina

This article reports on the status of plantation forestry in Misiones (North-East Argentina) and describes results from recent experiences on land restoration projects using indigenous tree species. The ﬁndings of this research are already being used in community forestry projects in the region, which include open mixed and single-species plantations and enrichment planting in degraded secondary forests.

Balfourodendron riedelianum (Rutaceae, “guatambú blanco”), 13 year-old, grew best on site 3, the most fertile, in a private property near the town of Santiago de Liniers, in comparison with growth in the most degraded site. The growth of this species was better at this site than in other trials in the region where B. riedelianum has been tested in enrichment plantings. Photo F. Montagnini. BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) 52 Florencia Montagnini, Beatriz Eibl, FOCUS / REHABILITATION OF LANDS Roberto Fernández

RÉSUMÉ ABSTRACT RESUMEN

RÉHABILITATION DE SOLS DÉGRADÉS REHABILITATION OF DEGRADED RESTAURACIÓN DE SUELOS À MISIONES, ARGENTINE LANDS IN MISIONES, ARGENTINA DEGRADADOS EN MISIONES, ARGENTINA

Misiones, province d’Argentine, couvre Misiones Province, in Argentina, cov- La provincia de Misiones representa moins de 1 % de la superficie du pays ers less than 1% of the total area of menos del 1% de la superficie de mais abrite 40 % de sa biodiversité et the country but harbors almost 40% Argentina, pero alberga casi el 40% de produit 70 % de son bois. Suite au of its biodiversity and produces over la biodiversidad y produce más del défrichage des forêts, de nouvelles uti- 70% of its timber. Forest clearing has 70% de la madera. Misiones ha tenido lisations des terres s’imposaient. Nous caused substantial changes, and cambios de uso de la tierra substancia- présentons les résultats de projets de alternative land uses have become les debido al corte de bosques, y son réhabilitation des terres intégrant des necessary due to soil degradation necesarios usos alternativos debido a essences indigènes. Des essais (1990- and land abandonment. This article la degradación de suelos y al abandono 1991) ont permis de tester Ilex para- presents the results of land rehabili- de tierras. Se presentan resultados de guariensis en plantations mixtes et en tation projects using indigenous tree proyectos de restauración de tierras uti- agroforesterie. La meilleure croissance species. In 1990-1991, trials began lizando especies arbóreas nativas. En sur sol pauvre était obtenue avec to test mixed plantations and agro- 1990-1991 se ensayó una serie de Enterolobium contortisiliquum et Astro- forestry with Ilex paraguariensis. plantaciones mixtas y sistemas agrofo- nium balansae. Les résultats pour Enterolobium contortisiliquum and restales con Ilex paraguariensis. Entero- Balfourodendron riedelianum, très pri- Astronium balansae showed the best lobium contortisiliquum y Astronium sée dans la région, étaient excellents growth on poor soils. Balfouroden- balansae tuvieron el mejor crecimiento en sol fertile, sous réserve d’une bonne dron riedelianum, a valued tree in en suelos pobres. Balfourodendron rie- gestion. L’association de ces essences this region, had excellent perform- delianum, una especie valiosa en la avec I. paraguariensis semble appro- ance on fertile soils and with ade- región, tuvo un comportamiento exce- priée, puisque les récoltes d’I. para- quate management. The association lente en suelos fértiles y con manejo guariensis permettent une rentabilisa- of trees with I. paraguariensis adecuado. La asociación de árboles tion rapide des investissements. Des appeared appropriate, since I. para- con I. paraguariensis fue aparente- essais d’enrichissement (1988-1990) guariensis harvests bring short-term mente apropiada, ya que las cosechas dans des zones forestières surexploi- returns on investments. Enrichment de I. paraguariensis representan un tées ont donné, sept ans après la plan- trials were established in 1988-1990 retorno de la inversión a corto plazo. En tation, les meilleurs résultats avec in overexploited forests. Seven years 1988-1990 se establecieron experi- Bastardiopsis densiflora, E. contortisili- after planting, the best species were mentos de enriquecimiento de bos- quum, Nectandra lanceolata, Ocotea Bastardiopsis densiflora, E. contor- ques sobreexplotados. A los siete años, puberula et Peltophorum dubium. tisiliquum, Nectandra lanceolata, las mejores especies fueron Bastar- Dans la réserve Guaraní, les meilleures Ocotea puberula, and Peltophorum diopsis densiflora, E. contortisiliquum, essences au bout de treize ans étaient dubium. In the Guaraní Reserve, the Nectandra lanceolata, Ocotea puberula O. puberula, B. densiflora et Cordia tri- best species at thirteen years were y Peltophorum dubium. En la Reserva chotoma. Ces essences ont également O. puberula, B. densiflora, and Cor- Guaraní, a los trece años las mejores des effets bénéfiques pour le sol, et dia trichotoma. These species also especies fueron O. puberula, B. densi- peuvent améliorer les forêts dégra- have beneficial effects on soils, and flora, y Cordia trichotoma. Estas espe- dées. L’intégration d’essences à rota- can thus improve the condition of cies también tienen efectos beneficio- tion plus courte (palmier Euterpe edu- degraded forests. Incorporating sos sobre los suelos, mejorando las lis) accélère la rentabilisation. Ces species with a shorter harvest age condiciones de los bosques degrada- résultats sont utilisés pour encourager (Euterpe edulis palm) can accelerate dos. La incorporación de especies con la plantation d’arbres dans le cadre de investment returns. These results are cosecha más temprana (palma Euterpe projets de sylviculture communautaire. being used to promote tree planting edulis) puede acelerar el retorno de la Les chercheurs fournissent conseils et in community forestry projects. inversión. Estos resultados se están uti- assistance ainsi que des plants et un Researchers provide tree seedlings, lizando para estimular la plantación de suivi de la plantation et de l’entretien. help planting and advise on estab- árboles en proyectos comunitarios. Los Les premiers résultats sont promet- lishment and caring. Initial results investigadores proveen los arbolitos, teurs et d’autres municipalités rejoi- are promising, and other municipali- ayudan a mantener los árboles y aseso- gnent les projets. ties are joining the projects. ran sobre el establecimiento y cuidado. Los resultados iniciales son promiso- Mots-clés : sol dégradé, plantation Keywords: degraded land, enrich- rios, y otras municipalidades se están d’enrichissement, essence autoch- ment planting, native species, plan- incorporando a estos proyectos. tone, plantation, bois, Ilex paragua- tation, timber, Ilex paraguariensis, riensis, Misiones, Argentine. Misiones, Argentina. Palabras clave: tierra degradada, enriquecimiento, especie nativa, plantación, madera, Ilex paraguariensis, Misiones, Argentina. BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) 53 RÉHABILITATION DE SOLS / LE POINT SUR…

Introduction

The Province of Misiones in Misiones forests, mature form, the Misiones forest con- north-eastern Argentina (25-28°S, tains an average of about 100 tree 53-56°W, elevation 100-800 m) past and present species per hectare. Species compo- (Figure 1) covers an area of approxi- sition varies with geographical loca- mately 30 000 km2, less than 1% of The Köppen system (Köppen, tion: for example, the presence of the total area of the country. However, 1918) classiﬁes the climate of Araucaria angustifolia (Bert.) O. Ktze. the Province of Misiones harbors Misiones as Cfa, where C stands for a (“pino Paraná”) in association with almost 40% of Argentina’s biodiver- mesothermic climate, f for lack of a tree ferns is restricted to higher ele- sity and produces over 70% of its tim- well-deﬁned dry season, and a for vations in the north-eastern part of ber (Gobierno de la Provincia De subtropical. Annual precipitation the province, while Aspidosperma Misiones, 2003). In recent years, the ranges from 1700 to 2400 mm. polyneuron Müll. Arg. (“palo rosa”) in province of Misiones, which has tradi- Means temperatures over a 17-year association with the “palmito” palm tionally supplied timber products to period (1985-2002) are 25°C with a (Euterpe edulis Mart.) only occurs in the rest of the country and for export, maximum of 39°C for the hottest the North. The complex forest struc- has been applying the “multiple use” month (January), and 14°C with a ture includes trees reaching heights approach to its forest resources, to minimum of -6°C for the coldest of up to 40 m, with no single species include the use of non-timber forest month (July) . reaching “importance values” greater products and to develop environmen- The Paranaense forest, a typical than 8%. Importance values are gen- tal and recreational forest services. forest formation in Misiones, is one erally calculated as the average of However, alternatives for land of the most diverse ecosystems in the relative abundance and relative use are clearly necessary to support both Argentina and Paraguay. In its frequency of each species in forest current economic and ecological needs: inappropriate land uses and management, such as the prolifera- tion of shifting agriculture or inade- quate soil techniques in plantation management, have often led to soil degradation and subsequent abandonment of lands in the region (Montagnini, Jordan, 2005). In 1989, the Yale School of Forestry and Environmental Studies (FES) signed an agreement with the School of Forestry at the National University of Misiones (UNaM) to carry out collaborative studies in reforestation and agroforestry. s Experimental single-species and ne io mixed plantations, agroforestry sys- is M tems on degraded land and enrichment trials in degraded forests were established using native trees of eco- a tin nomic value (Fernández et al., 1997; en rg Montagnini et al., 1998; Eibl et al., A 2000). This article reports on the status of plantation forestry in Misiones and advances results of recent experiences on land restoration projects using indigenous tree species in the region.

Figure 1. Map of South America showing the location of the Province of Misiones (in red) in north-eastern Argentina, on the border with Paraguay and Brazil. 54 BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) FOCUS / REHABILITATION OF LANDS

The establishment of industrial plantations

A forest inventory revealed that the total area of natural forests in Misiones amounted to 2 600 million hectares in 1850, but as a result of logging and clearing to establish plantations and agriculture, only 1 222 million hectares remained by 1977 (Gobierno de la Provincia De Misio- nes, 2003). This was largely the conse- quence of government incentives for commercial plantations of pulpwood (principally Pinus elliotii E. and Pinus taeda L.), and cash crops such as soy- beans, “yerba mate” (South American holly, Ilex paraguariensis Saint Hilaire, Aquifoliaceae) and tea. The first tree plantations were established in the 1920s with the native species Araucaria angustifolia. Pines, which were first planted in Mixed plantation of native tree species: Enterolobium contortisiliquum 1948, and now dominate the land- (Fabaceae, “timbó colorado”), Lonchocarpus muehlbergianum (Fabaceae, “rabo scape in Misiones, especially in the molle”), Astronium balansae (Anacardiaceae, “urunday”), and Peltophorum West of the Province along the Paraná dubium (Fabaceae, “caña fístula”), 8 to 13 year-old depending on the species. Site 1, the most degraded of the experimental sites, is located on land around river. The first cellulose and paper the Escuela Agrotécnica, owned by the National University of Misiones. plant was installed in the 1950s near Photo F. Montagnini. the town of Eldorado on the Paraná river. The cellulose and paper industry soon consumed all natural and inventories, where individuals of have a minimum stipulated diameter planted supplies from araucarias, each species are counted in sample at breast height (dbh) of 40 to 55 cm, and had to rely on plantations of plots. Importance values below 10- depending on the species. pines and eucalypts to meet their 15% are typical of very diverse Natural protected areas cover a needs for fiber. By the mid-1980s, forests where no single species is total of 481 000 hectares (almost there were already over 150 000 dominant, leaving room for other 16% of the provincial territory). The 53 hectares of forest plantations, and as species (Odum, 1983). In the Protected Areas of different categories a result, forest cover in the province, Misiones forests there is also a dense include national parks and reserves, including plantations, had increased understorey of lianas, tree ferns, 17 provincial parks, 16 private parks to 67% by 1985. palms and bamboos, small shrubs and wildlife refuges, one biosphere Due to the relatively low prices and herbaceous plants. reserve, and one conservation and paid by the cellulose industries for In Misiones, about 200 local pro- sustainable development area known plantation pulpwood, sawmills har- ducers own forest lands subject as the Green Biological Corridor vesting timber for boards began to to Forest Management Plans, bringing (“Corredor Verde”). Protected areas proliferate, especially in the northern the total area of managed forest to are found throughout the province of part of the province, later spreading almost 500 000 hectares (Gobierno Misiones, although the largest tracts to the rest of the province. The advan- de la Provincia De Misiones, 2003). are in the North-East where the Iguazú tages for the development of the pulp Timber extraction is subject to mini- National Park and the Corredor Verde and timber industry in Misiones mum diameter regulations (Monta- are located. In general, all ecosystems were: i) the high yields and relatively gnini et al., 1998 and 2001). Under in the Paranaense forest are being pre- short rotation times of plantation the Minimum Diameter cutting method served in these protected areas species; ii) availability of high quality that prevails in Argentina, commercial (Gobierno de la Provincia De Misio- labor; and iii) highly diversified natu- species may only be extracted if they nes, 2003). ral forest resources. BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) 55 RÉHABILITATION DE SOLS / LE POINT SUR…

Today, Misiones has about nia spp., Toona ciliata M. Roem., Gre- Alternative land 330 000 hectares of planted forest. villea robusta A. Cunn., and the use systems In 2003, total production of round- native Araucaria angustifolia. In wood from plantations in Misiones Misiones, the area planted with for ecosystem was about 5 million m3, or 70% of native tree species (Araucaria angus- restoration total production, with the remainder tifolia and a few others) covers less in Misiones supplied from natural forests. than 10% of the total area of forest Most plantations consist of plantations. This situation is partly exotic species such as Pinus spp. due to insufﬁcient information A number of initiatives were (P. elliotii, P. taeda, and others), regarding suitable silvicultural meth- started in 1980-1990 as part of the Melia azedarach L. var gigantea ods for establishing and managing Yale School of Forestry and (“paraíso”), Eucalyptus spp., Paulow- plantations of native species. Environmental Studies (FES) collaborative agreement with the School of Forestry at the National University of Misiones (UNaM). The trials focused on ﬁnding alternatives to restore degraded forests and lands that had been abandoned by agriculture or other land uses. The trials included mixed and single-species plantations, agroforestry systems and forest enrichment planting. All trials used indigenous species of economic value, building on local knowl- edge and previous research on ecological characteristics of the species.

Plantations and agroforestry systems using indigenous tree species

In view of the difﬁcult economic and social situation currently prevailing in the province, practical solu- tions are urgently needed to increase productivity and lessen the negative impacts of land use on existing resources. Local farmers are willing to try new alternatives for ecosystem restoration, including agroforestry combinations with the most common cash crops. In order to suggest pro- ductive alternatives for restoring degraded soils, experiments to test the adaptability of native tree species to three sites with different degrees of soil degradation were started in 1990-1991. These trials included mixed plantations and agroforestry systems with yerba mate (Ilex Balfourodendron riedelianum (Rutaceae, “guatambú blanco”), 13 year-old, paraguariensis), the most common growing on moderately degraded soils in site 2, in a private property near the cash crop in the province. town of Eldorado. After surviving the critical establishment stage, this valuable At all three sites used in this timber species grew well on low-fertility soils. Notice yerba mate (Ilex paraguariensis, Aquifoliaceae) bushes growing in the understorey. research, the terrain is gently undu- Photo F. Montagnini. lating, with slopes of less than 6%. The soil, of the Great Group Kandiu- 56 BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) FOCUS / REHABILITATION OF LANDS

dults type according to the US Soil The native tree species tested Growth results of the native tree Taxonomy classification (Fernández were: Enterolobium contortisiliquum species are shown in Tables II-IV. In et al., 1997), is reddish, deep, well to (Vellozo) Morong (Fabaceae, “timbó the most degraded site (site 1), moderately well drained, with clay colorado”, Lonchocarpus muehlber- Enterolobium contortisiliquum had throughout the profile. These soils gianum Hassler (Fabaceae, “rabo the best growth, suggesting its use to have low fertility and are poor in molle”), Astronium balansae Engl. restore poor soils (Table II). In other organic matter, nitrogen, phospho- (Anacardiaceae, “urunday”), Pel- experiments within the same region, rus, and other nutrients (Table I). Due tophorum dubium (Sprengler) Taubert E. contortisiliquum showed good per- to their degraded condition, the suit- (Fabaceae, “caña fístola”), Balfouro- formance when grown under 18 year- ability of these soils for tree planta- dendron riedelianum (Engler) Engler old pine plantations (P. elliottii ) with tions is poor to moderate. (Rutaceae, “guatambú blanco”) and a density of 300 trees per ha. When The most degraded site (site 1) Tabebuia heptaphylla (Vellozo) Toledo planted under pine, E. contortisili- had been used for agriculture for over (Bignoniaceae, “lapacho negro”). quum trees grew about one meter in 40 years. In contrast, site 2, with mod- These species were selected for height per year and by one cm dbh erate degradation, was an abandoned their ability to grow in full sunlight and per year at four years of age, while field that had been used for agriculture for their potential positive effects on their growth in the open was affected for about 20 years and was subse- soils, as indicated in previous experi- by attacks of Epicauta adspersa quently invaded by grasses (Andro- ments, as well as for their timber value (“bicho moro”), a beetle that consu- pogum spp., Pennisetum spp.). Site 3 (Eibl et al., 2003). In Misiones, sev- mes the foliage (Crechi et al., 2002). was the least degraded, and had sus- eral private companies have planted Epicauta adspersa had also initially tained a plantation of tung (Aleuritis some of these species as part of their affected the survival and growth of fordii Forst.) for about 20 years. own research, and the UNaM this species at site 3, but the trees Although the soils at the three researchers had visited these trials. later recovered from the attacks. sites belonged to the same Great UNaM researchers have also con- Enterolobium contortisiliquum also Group of classification, the different ducted several studies on the ecology grew well in enrichment planting trials use histories mentioned above has of the most common tree species of in the Guaraní Forest Reserve in produced very different soil degrada- the Misiones forest, with the objective Misiones (Montagnini et al., 1997). tion situations at each site. Site 1 had of determining their potential for tim- In addition, concomitant research the highest degree of physical degra- ber production and other alternative results suggest the ability of this dation, as shown by its structural uses. It was expected that the legumi- species to improve soil nitrogen and characteristics and high bulk density, nous species would contribute to base cation concentration (Fernan- with the resulting aeration problems higher nitrogen availability in soils, as dez et al., 1997), an excellent advan- and restrictions on plant root growth. suggested by results of studies by tage when growing this species in the In contrast, site 3 had the fewest UNaM researchers. In addition, stud- nutrient-poor conditions of highly symptoms of physical degradation. ies of the effects of some of the tree degraded sites. The same patterns appear in the species on soils have been conducted Astronuim balansae was also chemical quality of soils at each site. by Yale FES and UNaM researchers, to observed to be well suited to the Nutrient content in site 3 was 2-3 compare soils under the tree canopy degraded soil conditions of site 1, con- times higher than in site 1, and site 2 with grass-covered soils in adjacent trary to Lonchocarpus muehlber- had intermediate values for the areas (Fernandez et al., 1997). gianum, Balfourodendron riedelianum parameters examined (Table I).

Table I. Chemical characteristics of soils before planting for the three sites under study.

Site Soil Organic Total Extractable pH Ca2+ Mg2+ K+ Sum of CEC depth matter nitrogen P in H2O bases (cm) (%) (%) (ppm) (cmol+/kg) (cmol+/kg) (cmol+/kg)

Site 1 0-10 2.1 0.09 1.5 5.2 4.3 1.1 0.20 5.6 7.7 10-30 0.9 0.07 1.0 5.1 3.6 1.0 0.09 4.7 7.0 Site 2 0-10 2.6 0.24 3.2 5.2 5.8 1.5 0.29 7.6 10.7 10-30 1.4 0.12 1.3 4.7 4.2 0.9 0.11 5.2 8.7 Site 3 0-10 3.9 0.31 5.4 5.4 8.6 2.3 0.41 11.3 19.6 10-30 2.3 0.20 4.4 4.6 6.4 1.3 0.21 7.9 12.8

Analyses of organic matter, total nitrogen, pH, CEC, extractable Ca2+, Mg2+, K, and P were performed following standard procedures for tropical soils (Anderson, Ingram, 1989; Fernandez et al., 1997). BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) 57 RÉHABILITATION DE SOLS / LE POINT SUR…

Table II. Growth in diameter at breast height, total height and survival of four native tree species in single-species and mixed plantations in site 1.

Species Diameter (cm) Height (m) Survival (%) (Standard deviation) (Standard deviation)

Enterolobium contortisiliquum single- 25.4 (5.88) a 11.82 (2.36) a 46 c species Planted August 1990 max. 41 max. 15.8 min. 13,2 min. 6.3 Enterolobium contortisiliquum mixed 25.3 (4.67) a 10.57 (1.60) a 70 a Planted August 1990 max. 34.3 max. 14 min. 14.9 min. 9 Peltophorum dubium single-species 8.45 (3.00 ) c 6.57 (1.67) d 78 a Planted August 1995 max. 18 max. 15 min. 3 min. 2.3 Peltophorum dubium mixed 10.24 (2.36) b 9.18 (1.69) b 56 b Planted August 1995 max. 18.2 max. 11.5 min. 5 min. 5.4 Astronium balansae single-species 10.18 (2.14) b 6.78 (4.2) d 59 b Planted August 1993 max. 18.7 max. 13.6 min. 4 min. 4.7 Astronium balansae mixed 10.91 (2.04) b 8.23 (1.22) c 78 a Planted August 1993 max. 13.7 max. 10.6 min. 7.4 min. 4.8 Lonchocarpus muehlbergianum single- 7.4 (1.19) d 4.4 (0.93) e 48 c species Planted August 1990 max. 9 max. 6 min. 4 min. 2.4 Lonchocarpus muehlbergianum mixed 2.8 (1.43) e 2.75 (0.56) f 28 d Planted August 1990 max. 3.8 max. 3.6 min. 2.5 min. 1.5

Measurements done in December 2004. The experimental design consisted of randomized blocks with four replicates. Statistical analyses were performed using Variance Analysis (ANOVA) and the Duncan test for means, with p<0.05. Different letters indicate signiﬁcant differences among groups.

Table III. Growth in diameter at breast height, total height and survival of three native tree species in agroforestry systems in site 2.

Species Diameter (cm) Height (m) Survival (%) (Standard deviation) (Standard deviation)

Enterolobium contortisiliquum 19.3 (4.18) a 7.92 (1.27) a 46 b Planted August 1991 max. 28.6 max. 10 min. 10 min. 4.15 Balfourodendron riedelianum 9.85 (2,09) c 8.16 (1.72) a 92 a Planted August 1991 max. 15.5 max. 12.9 min. 7 min. 5.8 Tabebuia heptaphylla 14.87 (3.67) b 7.97 (0.94) a 90 a Planted August 1993 max. 25 max. 10 min. 6 min. 4,9

Measurements done in December 2004. The experimental design consisted of randomized blocks with four replicates. Statistical analyses were done using Variance Analysis (ANOVA) and the Duncan test for means, with p<0.05. Different letters indicate signiﬁcant differences among groups. 58 BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) FOCUS / REHABILITATION OF LANDS

Commercial pulpwood plantations (principally Pinus elliotii and P. taeda) dominate the lowland landscape in Misiones. Note the natural forest cover on the top of the hill. Photo F. Montagnini.

and Bastardiopsis densiﬂora, which grew higher and to a larger diameter Liniers (Table IV). The growth levels did not grow well on highly degraded than in single-species stands. On found at site 3 (Table IV) exceeded sites. Although it may be too early to medium fertility soils at site 2, the those found in other trials in the draw conclusions on P. dubium’s best species were E. contortisiliquum region where B. riedelianum had adaptability to degraded sites, this and T. heptaphylla (Table III). been tested in enrichment plantings, species seemed to have low nutrient Balfourodendron riedelianum where soil conditions are generally requirements and to be sensitive to demonstrated better growth on sites good (Montagnini et al., 1997). soil compaction problems, therefore 1 and 2, with higher fertility and less However, B riedelianum is apparently requiring good soil preparation includ- soil compaction than site 1 (Table IV). very sensitive to degraded soil condi- ing subsoiling down to 60 cm in depth. Overall, the best growth performance tions, as in the case of site 1 (Table II), On site 1, the mixed plantations values were recorded for B. riede- where it could not be established due grew well in comparison with single- lianum, one of the most prized tree to high mortality or very slow growth. species stands, with the exception of species locally. In contrast to E. con- On site 2 (Table III) B. riedelianum Lonchocarpus muehlbergianum tortisiliquum and A. balansae, which grew poorly during the ﬁrst couple of (Table II). The advantage of mixed E. appeared to be well suited to the years, possibly due to the low soil fer- contortisiliquum and A. balansae most degraded sites, B. riedelianum tility. However, once it survived the plantations was a higher survival rate grows well in fertile soils and with critical stage of establishment, this than in single-species stands, while adequate silvicultural management, species grew well in low-fertility soils, P. dubium planted in a mixture with as observed by tree heights of to 8.16 meters in height and 9.85 cm Lonchocarpus muehlbergianum, 11 meters and 15.7 cm dbh reached dbh after 13 years (Table III). E. contortisiliquum and A. balansae after 13 years at site 3, Santiago de

Table IV. Growth in diameter at breast height, total height and survival of two native tree species in agroforestry systems in site 3.

Species Diameter (cm) Height (m) Survival (%) (Standard deviation) (Standard deviation)

Enterolobium contortisiliquum 16.9 (5.3) a 7.7 (1.6) b 62 b Planted August 1991 max. 25.7 max. 11.3 min. 5 min. 4.6 Balfourodendron riedelianum 15.7 (3.7) b 11.3 (2.3) a 75 a Planted August 1991 max. 26 max. 16 min. 7.2 min. 5.3

Measurements done in December 2004. The experimental design consisted of randomized blocks with four replicates. Statistical analyses were done using Variance Analysis (ANOVA) and the Duncan test for means, with p<0.05. Different letters indicate signiﬁcant differences among groups. BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) 59 RÉHABILITATION DE SOLS / LE POINT SUR…

A forest area showing recent selective cutting in accordance with the minimum diameter system, in the Guaraní Forest Reserve, administered by the National University of Misiones. The remaining basal area after harvest was about 10 m2/ha. Enrichment trials were established in these residual forests in 1990. Photo F. Montagnini.

In these trials, the association of The results of this research are Enrichment planting timber trees with yerba mate seemed currently being used to stimulate tree in degraded appropriate, since yerba mate pro- planting in community forestry proj- and secondary forests duced good harvests yielding a short- ects in municipalities near Eldorado, term return on investment. Several the town where the School of Forest Line enrichment trials using crops such as cassava, maize, Sciences of the National University of native species of commercial value peanuts, peppers, sweet potatoes, Misiones is located. The university were established in 1988-1990 in beans, sweet peas, onions, water researchers provide tree seedlings, overexploited forests in Misiones, melons, and cucumbers were inter- help with tree planting and advise on on public and private lands. Two of cropped with the trees at site 2. species establishment and care. the trials were conducted on the Production from the associated sub- Local people with limited economic property of Celulosa Argentina S.A., sistence crops at site 2 covered the resources help to take care of these located in the North-East of farmer’s annual needs (Eibl et al., plantations, which are expected to the province in Paraje Gramado, 2000). This plus the long-term returns provide forest products and improve Department of San Pedro (26° 38’ S, from timber make the systems pro- the environmental conditions (soil, 54° 08’ W, 530 m in elevation). The posed here an interesting alternative water quality) of the watershed. Celulosa Company owns about for small farmers in the region. Other Initial growth results among native 7 500 ha of native forest where agroforestry systems including native trees for timber, fuelwood and fruit in selective thinning is carried out and exotic species are common in the degraded areas are promising at one using the conventional minimum region. In particular, agrosilvopas- of the sites, the arroyo Pomar water- diameter method. This forest was toral systems with improved cattle shed, and other municipalities intend logged in 1986 and the remaining breeds are helping many farmers to to join and initiate similar tree plant- basal area (trees >10 cm dbh) after accelerate returns on plantations, ing projects. harvest was less than 10 m2 /ha especially from araucarias and pines. (Montagnini et al., 1997). 60 BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) FOCUS / REHABILITATION OF LANDS

Table V. Growth in diameter at breast height, total height and survival of four native tree species in forest enrichment experiments trials at the Guaraní Reserve.

Species Diameter (cm) Height (m) Survival (%) (Standard deviation) (Standard deviation)

Ocotea puberula 19.08 (6.9)a 9.9 (2.9)a 75 a max. 28.6 max. 14.8 min. 3.5 min. 3.5 Balfourodendron riedelianum 4.3 (2.4)c 5.87 (2.4)c 55 c max. 10 max. 9.9 min. 1.0 min. 2.4 Bastardiopsis densiﬂora 13.3 (5.6)b 10.4 (2.7) a 65 b max. 20.8 max. 14 min. 5 min. 5.5 Cordia trichotoma 10.9 (4.6)b 8.6 (2.2) b 75 a max. 23 max. 12.3 min. 4.7 min. 4.3

Measurements made in November 2004. Tree species were planted in 1991. The experimental design consisted of randomized blocks with four replicates. Statistical analyses were done using Variance Analysis (ANOVA) and the Duncan test for means, with p<0.05. Different letters indicate signiﬁcant differences among groups.

Another trial was conducted in years). In the Misiones forests, about the Guaraní Forest Reserve, 40 m3/ha of commercial trees are Department of Guaraní (26° 15’ S, 26° usually extracted using the minimum 56’ W, 267-574 m in elevation), also diameter method, and the tree basal located in the North-East of the area of the residual forests ranges province, approximately 150 km from from 10 to 15 m2/ha (Montagnini et San Pedro. This 5 340 ha reserve was al. 1998 and 2001). In the region, established in 1975 and is managed residual forests with <15 m2/ha are by the Department of Forest Science at considered to be overexploited, with the National University of Misiones. relatively slow natural regeneration, Guaraní is part of the Yabotí Forest and enrichment planting is recom- Reserve covering 250 000 hectares, mended to accelerate their recovery. which was integrated into the UNESCO Ten timber species were tested, Biosphere Reserve Program in 1994. as well as the palm Euterpe edulis The ﬂoristic composition and Mart. (“palmito”) which can be har- physical characteristics of the forest vested after 10-12 years for its palm reserve are typical of most native heart. The enrichment trials involved forests in the province. Most of the cutting lines running east to west in reserve remains pristine; only 1 000 the forest to provide more light for hectares, i.e. 20% of the total area, planted seedlings. All lines were ini- have been allocated for research use. tially 2 m wide and were widened to 4 Trials were conducted in an area or 6 m in the second or third year after where the undisturbed forest had planting to increase light incidence for been harvested in 1990, and the each species. This was done based on remaining basal area after harvest general information on the species’ was about 10 m2/ha. light requirements gathered from The overall aim of enrichment other trials in the region. Seedlings was to improve forest composition in were one year-old, 40-50 cm tall nurs- Enterolobium contortisiliquum (Fabaceae, “timbó Colorado”), terms of both quantity and quality of ery specimens raised in pots. 13 year-old, growing on commercially important species, so Seedlings that died were replaced up moderately degraded soils in as to allow harvests from short and to the third year. The enrichment lines site 2, in a private property near medium cutting cycles (15 to 40 were weeded 2-3 times per year dur- the town of Eldorado. This native nitrogen-ﬁxing tree performed best in the most degraded sites. Photo F. Montagnini. BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) 61 RÉHABILITATION DE SOLS / LE POINT SUR…

The association of timber trees with yerba mate shrubs appears to be an appropriate agroforestry combination, with a short-term return on investment from the yerba mate leaf harvests, and production from corn and other subsistence crops. Photo F. Montagnini.

At the Guaraní Forest Reserve, those in areas beyond the influence from measurements taken in of the canopy (Fernández et al., Tabebuia heptaphylla December 2004, the timber species 1997). The pH was also observed to (Bignoniaceae, “lapacho negro”), with greatest mean height and dbh be better under Bastardiopsis densi- 11 year-old, growing on 13 years after planting were Ocotea flora and Cordia trichotoma com- moderately degraded soils in site puberula, Bastardiopsis densiflora, pared to adjacent areas with no trees, 2, in a private property near the ++, ++ town of Eldorado. Together with and Cordia trichotoma (Table V). while the sum of bases (Ca Mg Enterolobium contortisiliquum, Ocotea puberula, a prized timber and K+) was highest under Cordia tri- this species performed best under species, had suffered severe attacks chotoma, Bastardiopsis densiflora low and medium soil fertility from a stem borer beetle, Oncideres and Enterolobium contortisiliquum. conditions, in comparison with the other species in this trial which did gutturator Fabr. (Cerambycidae), Thus, these species which perform not adapt to degraded soils. locally known as “quiritó”, “cortapa- well in enrichment planting may also Photo F. Montagnini. los” or “taladro podador”, an insect be beneficial by improving soil char- that cuts the lateral and terminal acteristics of degraded forest areas. branches of several important timber ing the first three years and once or species in the Misiones forest Feasibility of enrichment twice per year thereafter as needed. (Vizcarra, 1990). After severe planting At the San Pedro site, seven Oncideres gutturator attacks, the years after planting, the timber Ocotea puberula trees in the enrich- Because of the relative complex- species with the greatest mean height ment trial re-sprouted vigorously, ity of enrichment planting manage- and dbh were Bastardiopsis densi- producing the largest stem growth of ment, some authors consider it eco- flora (Hook et Arn.) Hassl. (Malvaceae, the four species tested. nomically viable only for small or “loro blanco”, Enterolobium contor- Bastardiopsis densiflora and medium scales (Ramos, Del Amo, tisiliquum, Nectandra lanceolata Nees Cordia trichotoma were next in terms 1992). The high cost of establishing et Mart ex Nees (Lauraceae, “laurel of height growth (Table V). Bastar- and maintaining plantings in the early amarillo”), Ocotea puberula (Nees et diopsis densiflora, a prized timber years has been cited as one disadvan- Mart.) Nees (Laureaceae, “laurel species, grows well in secondary tage of enrichment techniques. guaicá”, and Peltophorum dubium forests forming dense, single-species However, including species of (Montagnini et al., 1997). Two highly species stands. Previous experi- medium and shorter harvest age valued timber species, Cordia tri- ments on the effects on soils of could improve the economics of this chotoma (Vell.) Johnst. (Boraginaceae, native tree plantations established technique, and enrichment planting “peteribí”, “loro negro”), and Bal- that the greatest differences in C and could play an important role in the fourodendron riedelianum, could also N soil concentrations were found recovery of degraded forests (Weaver, be recommended for enrichment under Bastardiopsis densiflora, 1987; Montagnini et al., 1997). despite their relatively slow growth. where they were twice as high as 62 BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) FOCUS / REHABILITATION OF LANDS

Bastardiopsis densiﬂora Hassl. (Malvaceae, “loro blanco”), one of the fastest growing species in the San Pedro and Guaraní enrichment trials. This species forms dense stands in secondary forest areas of the region and is a prized timber tree. Photo F. Montagnini.

and Willughbeia spp., was an eco- sonnel and the costs associated with nomically and ecologically viable tending may limit the widespread alternative (Schulze et al., 1994). applicability of this approach, espe- Another option is to combine timber cially at large scale. trees with species that produce an In other trials in private proper- earlier profitable harvest, such as the ties in Misiones using some of the Bamboos tend to dominate, palm E. edulis, to accelerate returns same species as in this article, the competing with natural on investment and to make this tech- economic profitability of enrichment regeneration from woody species nique more economically attractive. planting was calculated (Sánchez et in gaps and openings with a large Management of enrichment al., 1993). For a 25-year rotation, and amount of light as a result of plantings should be complemented by using expected prices for timber from selective cutting. In this situation, enrichment planting can be an tending of natural regeneration within native species, these authors calcu- alternative to accelerate forest the lines. The weeding necessary for lated a 11.2% rate of return on the recovery. initial establishment and maintenance investment. Although this was high, it Photo F. Montagnini. of the enrichment lines also tends to was lower than the returns expected favor natural regeneration. Therefore, from other investment alternatives at silvicultural treatments should be the time. However, the growth rates An alternative to compensate designed to encourage the establish- estimated by these authors were low, for the high labor costs of enrichment ment and growth of line plantings and being based on the density of about is to plant species that grow quickly at the same time favor natural regener- 180 to 200 trees per ha generally used and/or yield highly valued products. ation, especially of commercially for enrichment in the region. As dis- In Indonesia, enrichment of depleted important species (Sips, 1993). Once cussed above, other trees from natu- dipterocarp forests has become an the seedlings are established, the ral regeneration that are tended and economically attractive alternative whole forest should be tended favored while practicing enrichment due to increasing lumber prices (Kor- throughout, not just along the enrich- planting should be added in the esti- pelainen et al., 1995). In another ment lines (Dawkins, 1961). If regener- mation of final yields. In addition, the example, sensitivity analysis of ation in the enrichment lines is consid- authors pointed out that enrichment enrichment plantings in Kalimantan, ered together with planted trees, planting is a low-risk investment in Indonesia, showed that enrichment enrichment planting may become a comparison to other alternatives in of secondary forest with fruit trees, more economically attractive alterna- the region, so that a relatively lower such as Dialium spp., Garcinia spp., tive. However, the need for trained per- rate of return could be acceptable. BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) 63 RÉHABILITATION DE SOLS / LE POINT SUR…

Conclusions

Despite the fact that in Argentina, the National Forestry Law does not exclude native species for subsidizing Partial view of the arroyo Pomar watershed, where university researchers are open plantations or enrichment plant- collaborating with resource-poor local people in tree planting projects. Early ing, few farmers are interested in results for the growth of native trees for timber, fuelwood and fruit are promising, planting native species. This is mainly and other municipalities are intending to join and initiate similar projects. due to the lack of guarantees regarding Photo F. Montagnini. the returns that can be expected from native species. For open plantations, They also suggested that other indi- areas and are used by honey bees such subsidies are given only for single rect benefits, such as environmental as Solanum granuloso leprosum Dun. species planted in blocks. The results protection and ecotourism, ought to (Solanaceae, “fumo bravo”), Trema of this study have increased the body be considered in evaluating the prof- micrantha (L.) Blume (Ulmaceae, “palo of information on the growth and profitability of enrichment practices. pólvora”, and Brassica spp., among itability of native species used for However, these environmental bene- others, are tended and encouraged. open plantations and enrichment fits may not be directly perceived by The combination of species that regen- planting in Misiones, and can thus the local farmers, and initial govern- erate naturally and timber species that help to encourage more farmers in the ment subsidies would therefore be are planted for enrichment results in a region to plant native species. needed to bring this practice into mixed forest that lessens the risk of The findings from this study are more widespread use in the region. only planting species for which there is already being used in small commu- In Argentina, the 1999 National little background information on nity forestry projects in Misiones that Law (n° 25080) for the Promotion of growth. In addition, the species are include open mixed and single- Cultivated Forests subsidizes planta- expected to protect the soil and offset species plantations, and enrichment tions with native species as well as the adverse environmental conditions planting of degraded secondary with non-traditional exotic species, that are often found in degraded sec- forests or “capueras”. It is expected both in enrichment planting and in ondary forests, locally called that more farmers in the region will open plantation. For enrichment plant- “capueras”. join these projects and that the posi- ing, there is a restriction on the num- Enrichment adds value to previ- tive results in terms of growth and ber of trees that can be planted per ously logged, low-volume forests by environmental benefits will encour- hectare. In order to obtain the legal increasing the expected harvestable age more widespread planting of subsidies, there must be enough volume. This added value may prevent native tree species. information on growth of the pro- their conversion to plantations or Forestry development in the posed species, and sometimes the other prevailing uses. With increases province of Misiones has helped to native species are not approved for in the area of secondary and overex- increase productivity and to diversify subsidies due to lack of information. ploited forest across the globe the economy of the province, while This is where the results of the present (Achard et al., 2002), forest recovery respecting environmental con- research become important as back- will require techniques such as enrich- straints. Plantations for pulp and tim- ground information that can be used ment. In the province of Misiones, ber are expanding continually, but to promote enrichment planting of local farmers are seeking guidelines they are generally established on rel- native species of the Misiones forest. on species choice and management atively flat land whereas the upper In Misiones, UnaM researchers for the enrichment of overexploited elevations of watersheds and ripar- are working on proposals to obtain sub- and secondary forests. Though long- ian areas in the province are still sidies for enrichment plantings of sev- term results are required to document largely covered by natural forests. eral native species in secondary forest. potential growth and production qual- The relatively large proportion of for- This project would benefit small farm- ity for each species, results from the est under protected status ensures ers who are interested in producing trials described in this article can pro- conservation of the diverse ecosys- organic honey in community forestry vide insights into the use of these tems of the region. Their use in eco- projects. The project includes enrich- species for enrichment planting in tourism is also helping to diversify ment planting using some of the native overexploited and secondary forests the economy of the province. The timber species tested in this study. In in the Yabotí Biosphere Reserve and challenge is to ensure that forest the same areas, small trees and shrubs other areas in the region exposed to management complies with manage- that grow naturally in open, degraded similar conditions. ment plans, prevents illegal logging 64 BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) FOCUS / REHABILITATION OF LANDS

References Acknowledgements and controls the encroachment of The trials were initially established ACHARD F., EVA H. D., STIBIG H. J., people in the forest, especially from with funds from the Yale University MAYAUX P., GALLEGO J., RICHARDS T., the poorly protected borders with Center for International and Area MALINGREAU J. P., 2002. Determina- Brazil and Paraguay. In addition, Studies (YCIAS), the Latin American tion of deforestation rates of the implementation of forest restoration Studies Center of YCIAS, and a grant world’s humid tropical forests. Sci- projects such as those described in from the A.W. Mellon Foundation ence, 297: 999-1002. the present article can help to (USA). ANDERSON J. M., INGRAM S. I. (ed.), increase ecosystem productivity and 1989. Tropical soil biology and fer- preserve native resources. tility: a handbook of methods. CAB International, Wallingford, United Kingdom, 171 p. CRECHI E., FERNÁNDEZ R., DOMEQ C., HENNIG A., EIBL B., 2002. Silvicultura inicial de 3 especies latifoliadas nativas de interés económico en Misio- nes: peteribí, guatambú y timbó. IX Jornadas Técnicas Forestales. INTA- FCF-MEYRNRYT. Eldorado, Misiones, Argentina, Mayo 2002, Actas en Disco Compacto. DAWKINS H. C., 1961. New methods of improving stand composition in tropical forests. Caribbean Forester, 22: 12-20. EIBL B., FERNÁNDEZ R., KOZARIK J.C., LUPI A., MONTAGNINI F., NOZZI D., 2000. Agroforestry systems with Ilex paraguariensis (American Holly or yerba mate) and native timber trees on small farms in Misiones, Argentina. Agroforestry Systems, 48: 1-8. EIBL B., VERA N., MENDEZ R., 2003. Silvicultura de diez especies arbó- reas nativas con potencialidades para la producción de madera y otros usos alternativos. Facultad de Cien- cias Forestales. UnaM. Proyecto Forestal de Desarrollo-SAGPyA. Misio- nes, Argentina, 18 p. FERNÁNDEZ R., MONTAGNINI F., HAMILTON H., 1997. The inﬂuence of native tree species on soil chemistry in a subtropical humid forest region of Argentina. Journal of Tropical For- est Science, 10 (2): 188-196.

Euterpe edulis Mart. (“palmito”) in an enrichment trial at the Guaraní Reserve. Planting this species can accelerate returns on investment, since palm hearts can be harvested after 10-12 years. This palm does not grow well in open plantations, and is considered an endangered species in both Argentina and Brazil. Photo F. Montagnini. BOIS ET FORÊTS DES TROPIQUES, 2006, N° 288 (2) 65 RÉHABILITATION DE SOLS / LE POINT SUR…

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