The role of complex agroforestry systems in the conservation of forest tree diversity and structure in southeastern Ghana

The role of different agroforestry systems in the conservation of plant diversity and forest structure has not been directly compared in many agricultural dominated landscapes. In this study, we investigated tree diversity and forest structure in a complex agroforestry landscape traditionally grown for cocoa and mixed food crops and compared these to the natural forest in southeastern Ghana. The study was carried out using 36 25 m × 25 m plots. There was significant difference [95% Confidence Interval (95% CI)] in the native forest/non-crop tree species richness between the natural forest and the agroforest farmlands but species richness was similar between the cocoa and mixed food crops agroforests. The density of native forest/non-crop trees was significantly higher (P < 0.05) in the natural forest but similar between cocoa and mixed food crops agroforest. Similarly, the basal area of native forest/non-crop trees was significantly higher (P < 0.05) in the natural forest but comparable between cocoa and food crops agroforest. Of the 20 most abundant native forest/non-crop trees recorded, 12 of them showed significant responses (P < 0.05) to land use change with nine of the species significantly abundant in the natural forest relative to the agroforest systems. Eighteen native forest/non-crop trees species in the agroforestry systems were commonly recorded as being used; 100% of them being used as fuel wood with 83.3 and 77.8%, respectively, used as medicines and materials. The findings of this study suggests that although complex agroforestry systems are a poor substitute for the natural forest the heterogeneous mosaic landscape in which complex agroforestry forms part can be strategically managed to maximize the benefits of both sustainable agriculture production and conservation of plant diversity by acting as buffer between protected areas and intensively managed areas.     

Traditional agroforestry systems as tools for conservation of genetic resources of Milicia excelsa Welw. C.C. Berg in Benin

The potential contribution of agroforestry systems to the management and genetic resources conservation in iroko (Milicia excelsa), an important and valuable timber tree species in sub-Saharan Africa, is addressed in this paper. The structure and dynamics of traditional agroforestry systems and the ecological structure of Milicia excelsa populations in farmlands were studied through a survey carried out in 100 farmlands covering the natural range of iroko in Benin. Forty-five species belonging to 24 plant families were recorded in traditional agroforestry systems. Average tree density varied from 1 to 7 stems ha⁻¹ with diversity index ranging from 2.6 to 2.9. Milicia excelsa occurred sparsely in agroforestry systems in all regions, with density ranging from 1 to 4 stems ha⁻¹; stand basal area varying from 33.10⁻⁴ to 129.10⁻⁴ m² ha⁻¹, and negligible seedling regeneration. However, male and female trees were apparently evenly distributed on farmlands in all regions (F/M > 0). Iroko trees produced viable seeds with moderate germination rate and early growth (germination rate 22% and height 7.29 cm after 3 months). Suggestions are made regarding optimal densities for iroko conservation in farmlands, according to farmers’ socioeconomic conditions in different regions, in order to improve traditional agroforestry systems and their use as biological corridors in conservation of Milicia excelsa genetic resources.     

Nitrogen-Fixing Trees in Small-Scale Agriculture of Mountainous Southeast Guatemala

Abstract

Intensive, subsistence agriculture on hillsides of southeast Guatemala has caused extensive soil degradation. This retrospective study evaluated the success of an agroforestry treatment in improving the sustainability of mountainous agricultural systems in terms of soil nutrient status and erosion control. Three years after maize (Zea mays) and pasture fields were alley-cropped with N-fixing Gliricidia sepium trees, soil nutrient levels were examined and compared to nonalley-cropped controls. Agroforestry treatment showed significantly higher soil organic matter (SOM) over paired plots with no alley-cropping (mean 4.3% vs. 3.2% C, p < 0.05). Mean total N was also higher, with 0.12% in the nonagro-forestry control plots compared to 0.16% underthe agroforestry treatment (p <0.05). Some improvement in soil water-holding capacity(WHC) was also observed in the agroforestry systems. Differences in soil levels of available P, ranging from 8.0 to 64.4 μg/g, were not significant and correlated more with site than with agroforestry treatment versus control. Specific soil and site properties such as texture and slope as well as land use and ground cover management largely influenced improvements in soil nutrient status under the agroforestry treatment at each site. Despite increases in soil nutrients, maize plant productivity showed no response to the agroforestry treatment in terms of leaf chlorophyll index or maize plant height. Three years after the initiation of agroforestry, soil erosion rates showed no difference from paired controls; rates were correlated with ground cover and soil characteristics such as texture and surface rockiness rather than with agroforestry treatment. While soil nutrient status had not reached levels optimum for maize growth after three years, the positive trajectory of change in soil nutrients suggests the potential for using agroforestry systems in mountainous regions of Guatemala to increase the sustainability of agricultural production.     

Does Remoteness from Urban Centres Influence Plant Diversity in Homegardens and Swidden Fields?: A Case Study from the Matsiguenka in the Amazonian Rain Forest of Peru

Swidden cultivation is the traditional agricultural system in most parts of the Amazonian rain forest. In a remote area in the Manu National Park, Peru, this system was analysed in two indigenous Matsiguenka communities. Diversity of cultivated plants on fields and in homegardens are presented in the current study. Cultivated plants were noted on two to four plots per field on 46 fields, making a total of 126 survey plots. Nineteen homegardens were studied as well. Dominating species cultivated on fields is cassava (Manihot esculenta). Fruit trees such as the peach palm (Bactris gasipaes), guava (Psidium guajava) or Inga edulis, but also cotton (Gossypium barbadense) and a medicinal plant (Cyperus sp.) predominate in more than 75 % of the homegardens analysed. Species diversity increases steadily from 18 and 24 species on 1- and 2-year-old fields to 26, 29 and 66 species in young, medium old and old homegardens, respectively. Seventy-one different species in total were found in all homegardens analysed and 25 in swidden fields. Diversity of species cultivated in homegardens is low compared to other studies in the rain forest of the Amazon. This seems to be due to their remoteness from the next urban centre and to the fact that they are native communities with still low external exchange of information. These findings are in contrast to the hypothesis that remoteness from urban centres increases species richness because subsistence production is based on a broad variety of species. In contrast to species richness in homegardens, differences in species richness in swidden fields between the present and other studies could not be found.     

Fruitcrops in the cashew-coconut system of Kenya: their use,management and agroforestry potential

The cashew-coconut system in the Coast Province of Kenya was appraised to determine the efficacy and adoption potential of a fruitcrop based agroforestry intervention designed to increase the productivity of the system. Fruitcrops on farmers plots ranged between 16–22 species. They featured mainly as understorey trees in cashew-coconut plots and upper storey of foodcrop plots. Fruit tree management was generally poor.Between 67–100% of farmers interviewed were interested in planting more fruit trees on their farms. Envisaged cash generation was a major reason for their interest. Preferred species were generally adapted exotics. Preference was in the order ofMangifera indica, Citrus sinensis, C. reticulata > Cocos nucifera, Anacardium occidentalis, Carica papaya > Passiflora edulis var. flavicarpa,Ananas comosus, Syzygium cumini, Citrus limon, Musa sapientum, Persea americana > Musa paradisiaca, Citrus aurantifolia Annona spp. Locational differences existed in exact order of preference within the groupings. Constraints to fruit production included lack of improved fruit tree seedlings, low proficiency in fruit seedling production, transportation, no capital for initial investment, damage by wild animals, prolonged dry spells, and frequent die back of fruit trees. Based on its high adoption potential, a fruitcrop based agroforestry intervention is recommended for increasing the productivity of the cashew-coconut system of Kenya.Possible agroforestry technologies in which fruitcrops could feature are discussed.     

Trade-offs between rubber production and maintenance of diversity: the structure of rubber gardens in West Kalimantan, Indonesia

The goal of this study was to assess the potential of small-holder rubber cultivation in agroforestry gardens to fulfill simultaneously the goals of conservation and sustainable rural development. I examined the structure and species composition of trees in 11 rubber gardens in West Kalimantan, Indonesia, using a single 0.10 ha plot per garden. Although 41 distinct morphotypes were encountered, rubber (Hevea brasiliensis) dominated the sample of 370 trees. Richness within plots varied (3–15 morphotypes), as did the predominance of rubber (24–97% of all basal area, 24–91% of all individuals). The importance of rubber within a garden was significantly negatively correlated with the number of morphotypes present. This result suggests that tree diversity may limit potential productivity of rubber gardens. Thus, small-holders may not be willing to maintain diversity at the scale of a single garden. Although species-accumulation curves indicate that substantial tree diversity may exist across all rubber holdings, diversity is likely to be lost from the system if individual owners reduce species richness in their gardens. Rubber agroforestry as currently practiced in West Kalimantan is not an ideal model for matching rural development needs with the achievement of conservation goals. Other models, such as tengkawang- and durian-based fruit gardens, do exist in Kalimantan and elsewhere, and should be evaluated for incorporation into policy and development strategies.     

Traditional tree crop based agroforestry in coffee producing areas of Harerge,Eastern Ethiopia

A preliminary survey of seven coffee producing Awrajas (Provinces) in eastern Ethiopia revealed that there is a traditional tree crop based agroforestry system being practised by the farmers. Coffee (C. arabica) was found to grow under the shade of several trees, 16 species, usually intercropped by one or several, a total of 15, important grain, fruit, vegetable, stimulant, oil-seed and spice crops. The majority of the trees, 69%, is leguminous and Ficus spp. The system is characterized by the integration of crops, livestock and sometimes apiculture. Recommendations are made for future studies.     

Domestication of Irvingia gabonensis: 3. Phenotypic variation of fruits andkernels in a Nigerian village

Domestication of Irvingia gabonensis, a fruit tree grown in agroforestry systems in West and Central Africa, offers considerable scope for enhancing the nutritional and economic security of subsistence farmers in the region. Assessments of phenotypic variation in ten fruit, nut and kernel traits were made on twenty-four ripe fruits from 100 Irvingia gabonensis trees in Ugwuaji village in southeast Nigeria, a center of genetic diversity for this species. There were important differences between the young planted trees of this study and the older unplanted trees of a similar study in Cameroon. Significant and continuous tree-to-tree variation was found in fruit mass(69.0–419.8 g), flesh mass (59.5–388.8 g), nut mass (9.5–40.6 g), shell mass (4.9–30.9 g) and kernel mass (0.41–7.58 g); fruit length (49.2–89.3 mm) and width (46.2–100.5 mm) and flesh depth (12.9–31.4 mm), as well as considerable variation in flesh colour, skin colour, fruit taste and fibrosity. Some fruits were considerably bigger than those found in Cameroon. These quantitative results will help in the development of cultivars within participatory approaches to agroforestry tree domestication, and so promote poverty alleviation and sustainable agriculture. This revised version was published online in June 2006 with corrections to the Cover Date.     

Contrasting rooting patterns of some arid-zone fruit tree species from Botswana – I. Fine root distribution

To assess the possible degree of root competition from fruit trees which could potentially be used in agroforestry systems, fine root density of fruit trees Strychnos cocculoides Bak., Strychnos spinosa Lam. (Loganiaceae) and Vangueria infausta Burch. (Rubiaceae), as well as from the shrubby species, Grewia flava DC. (Tiliaceae) was investigated. Vangueria infausta had the highest fine root densities in both vertical and horizontal extensions. In Vangueria infausta fine root density decreased with increasing soil depth. For the other species in the 80 cm soil profile investigated, no significant changes in fine root density with soil depth were found. For Strychnos cocculoides almost no fine roots were detected in the upper soil horizon (0–20 cm). Using fine root surface area densities, exploration and exploitation indices were calculated. Vangueria infausta had the highest value of the exploration index compared to the other species. For use in agroforestry systems Vangueria infausta was estimated to be the most competitive of the investigated species, whereas Strychnos cocculoides seems to be the less competitive. Strychnos cocculoides has additionally spatial arrangements of fine roots favourable for agroforestry, slowly increasing with depth and additionally low concentrations in upper soil layers.     

The effects of management and plant diversity on carbon storage in coffee agroforestry systems in Costa Rica

Agroforestry systems can mitigate greenhouse gas (GHG) emissions, conserve biodiversity and generate income. Whereas the provision of ecosystem services by agroforestry is well documented, the functional relationships between species composition, diversity and carbon (C)-storage remain uncertain. This study aimed to analyze the effects of management (conventional vs. organic), woody plant diversity and plant composition on aboveground and belowground C-storage in coffee agroforestry systems. It was expected that organic farms would store more C, and that an increase in plant diversity would enhance C-storage due to complementarity effects. Additionally, it was expected that steep slopes decrease C-storage as a result of topsoil erosion. Woody plants were identified on 1?ha plots within 14 coffee farms (7 conventional and 7 organic). C-stocks in trees, coffee plants and roots were estimated from allometric equations. C-stocks in litter and topsoil (0?C25?cm) were estimated by sampling. On average, farms stored 93?±?29?Mg?C?ha^?1. Soil organic carbon accounted for 69?% of total C. Total C-stocks were 43?% higher on organic farms than on conventional farms (P?<?0.05). Conventional and organic farms differed in vegetation structure, but not in species diversity. It was found that the combined effect of farm type, species richness, species composition and slope explained 83?% of the variation in total C-storage across all farms (P?<?0.001). Coffee agroforestry in general and organic farms in particular may contribute to GHG mitigation and biodiversity conservation in a synergistic manner which has implications for the effective allocation of resources for conservation and climate change mitigation strategies in the agricultural sector.     

The role of indigenous trees for the conservation of biocultural diversity in traditional agroforestry land use systems: The Bungoma case study: In-situ conservation of indigenous tree species

In order to precisely assess the role of agroforestry for the conservation of (agro-)biological diversity there is a need to adjust sampling methods used in plant sociology. This study is on the contribution of agroforestry land use to the in-situ conservation of indigenous trees within a typical East-African smallholder farming system in Western Kenya. A modified approach to measuring species richness and abundance is presented. The selection of tree-rich structures was done according to management patterns rather than considering syntaxonomic classifications from the vegetation science point of view. This approach, which is better suited to the strongly human-influenced vegetation of agroecosystems, employs between-management unit diversity measures to help evaluate abundance and constancy of species in particular management units. The predominant off-farm vegetation patterns are riverine forests, rocky hillsides, hedgerows, wooded grassland relicts, woodlands or colline forest relicts and tree groves whereas the noticeable tree-rich on-farm management units are homegardens, homesteads, life fences, coffee- and banana-groves and annual cropping fields. 98% out of all indigenous tree species known from Bungoma, occur in off-farm lands. 53% of the indigenous tree species occur in tree rich on-farm management units while 47% of the indigenous trees are dependent on the maintenance of off-farm lands. Hedgerows embody the most promising secondary vegetation structure that shows ample potential to accommodate a wide range of indigenous perennial species outside the natural vegetation formations. The pattern of distribution of various vegetation structures, and the mixture with diverse tree-based on-farm plots are interesting features in regard to floristic and eco-diversity on a landscape level. In this respect, three areas that show different population densities and distinct agro-historical conditions were compared. In regions of particular high population density the degree of association of various functional land use forms and woodland structures – each characterised by its own floristic make-up – is comparatively high. In contrast, in regions with less population but that were settled at a later date, one encounters fewer stands of woody plants with lower numbers of species. This revised version was published online in June 2006 with corrections to the Cover Date.     

Process studies in aPinus radiata-pasture agroforestry system in a subhumid temperature environment. II. Analysis of dry matter yields in the third year

In this paper we analyzed the dry matter yields (DM) produced in an agroforestry trial consisting of pine trees grown over (1) Control (bare ground), (2) ryegrass/clovers (Lolium perene/Trifolium spp.), (3) ryegrass only, and (4) lucerne (Medicago sativa) during the third growing season between 1992 and 1993. In addition these pastures were grown alone in separate plots in the open. The results show that:

Assessment of small mammal diversity in coffee agroforestry in the Western Ghats,India

Coffee agroforestry is a conservation strategy that has shown promise to support the diversity of bird, bat, and insect communities, but few studies have focused on non-volant mammals in coffee farms. We assessed mammal diversity within coffee agroforestry systems in Kodagu, India and investigated the impacts of the non-native shade tree species, Grevillea robusta, on mammal diversity. Twenty farms, with varying amounts of G. robusta planted within the coffee farm, were sampled throughout three rainfall zones during the 4-month study period. We captured six species of small mammals, with indirect methods yielding an additional five species, totaling 11 mammal species. Contrary to current ecological thought, we found that increased amounts of G. robusta did not have a negative impact on either abundance or richness of mammals. Small mammal abundances were higher at farms with greater amounts of herbaceous ground cover and larger, mature shade trees, while small mammal species richness was found to increase with an increase in tree species richness as well as greater amounts of herbaceous ground cover. Additionally, small mammal abundance was higher at coffee farms closer to forested areas. Based on these findings, we suggest the maintenance or cultivation of shade tree richness, mature shade trees, and herbaceous ground cover within coffee farms and preservation of forested areas within the landscape to enhance coffee agroforestry habitat for non-volant mammals. We hope that these habitat requirements will be incorporated into conservation strategies for the promotion of biodiversity within coffee agroforestry systems.     

Biodiversity and socioeconomic factors supporting farmers' choice of wild edible trees in the agroforestry systems of Benin (West Africa)

Wild edible trees are expected to play a significant role in the crop diversification programs and agroforestry development in Africa. In the present study, the diversity of wild food species and socio-economical factors that support farmers' choice for the species used in these systems were assessed. A number of selected sites in each of the 3 climatic zones of Benin were surveyed. Data were collected through a field exploration and a semi-structured survey among 435 selected households throughout the country, using a questionnaire. The most culturally important species ranked by locals were determined for each climatic zone and the relations between the targeted species in traditional agroforestry systems and the reasons which support peasants' choices were described through a Principal Component Analysis. A total of 43 wild edible trees were found in the traditional agroforestry systems of Benin during the survey. Traditional agroforestry systems in the Guineo-Congolian zone turned out to be the most diversified with 29 species followed by the Sudanian zone with 22 species and Sudano-Guinean zone with 16 species. The most culturally important wild edible trees in traditional agroforestry systems in the Guineo-Congolian zone were different from those identified in Sudanian and Sudano-Guinean zones. Three main reasons that support peasants' ambition to conserve or to grow wild edible trees in their field were: their contribution to food, their use in traditional medicine and ceremonies and the farmers' perception of their availability in natural vegetation.     

Agroforestry systems and biodiversity conservation in arid zones: the case of the Tehuacán Valley,Central México

The role of agroforestry systems in biodiversity conservation was investigated in the semiarid Tehuacán Valley, Central México. Richness and diversity of native plant species were compared between agroforestry systems (6 sampling sites) and the following forests (6 sampling sites) dominated by columnar cacti: (i) “chichipera” dominated by Polaskia chichipe; (ii) “jiotillal” dominated by Escontria chiotilla; and (iii) “garambullal” dominated by Myrtillocactus schenckii. Our information on genetic variation of dominant arboreal species in the study sites was reviewed and included in the analysis. Factors influencing household’s decisions to maintain vegetation cover were compiled through a survey and interviews and analyzed. All the samples of the agroforestry systems studied maintained on average nearly 59% plant species and 94% genetic variation of dominant cacti occurring in the forests, although their ability to preserve endemic rare species is limited. Social factors favoring maintenance of perennial species in agricultural plots include collective rules, households traditions, use of the plants maintained in the systems, and the environmental information gathered from NGOs, the local Biosphere Reserve, and researchers. However, agroforestry systems are losing their capability to maintain vegetation cover, mainly because of (i) decreasing amount of land managed by households, determined by a progressive fragmentation of the land area given to new families, (ii) adoption of technologies to intensify agriculture, and (iii) governmental programs penalizing the presence of vegetation patches within agricultural lands since they are considered “useless” areas. Necessary policies to stop degradation of the agroforestry systems and to improve their conservation capacity are discussed.     

Shifting from simple to complex agroforestry systems: an example for buffer zone management from Kerinci (Sumatra,Indonesia)

Kerinci is a densely populated valley surrounded by a national park in western central Sumatra, Indonesia. Indigenous agroforestry systems include important cash crops like coffee (Coffea canephora var.robusta) and cinnamon (Cinnamomum burmani), and range from alternate cycles of cash crop monocultures or simple associations, to multispecies and multi-storey gardens; these may include as many as 100 common useful species, comprising many fruit trees and indigenous timber species.After analysing the trends of forest conversion and its causes in the area of Kerinci Seblat National Park, a case study of one particular village is presented in order to describe the evolution of cyclic agroforestry systems (ladang) into complex agroforestry systems (pelak). The composition, structure and management of the various systems have been studied through interviews, botanical surveys and the method of profile diagrams.It is suggested that locally developed complex agroforestry systems evolve partly in response to changes in land availability and labour constraints. Finally the interest of such systems when designing projected buffer zones and their development in relation to new market incentives are discussed.     

Productivity and nutrient cycling in young Acacia senegal farming systems on Vertisol in the Blue Nile region, Sudan

Acacia senegal, the gum arabic-producing tree, is the most important component of traditional dryland agroforestry systems in the␣Sudan. The spatial arrangement of trees and the type of agricultural crop used influence the interaction between trees and crops. Tree and crop growth, gum and crop yields and nutrient cycling were investigated over a period of 4 years. Trees were grown at 5 × 5 m and 10 × 10 m spacing alone or in mixtures with sorghum or sesame. No statistically significant differences in sorghum or sesame yields between the intercropping and control treatments were observed (mean values were 1.54 and 1.54 t ha⁻¹ for sorghum grain and 0.36 and 0.42 t ha⁻¹ for sesame seed in the mixed and mono-crop plots, respectively). At an early stage of agroforestry system management, A. senegal had no detrimental effect on crop yield; however, the pattern of resource capture by trees and crops may change as the system matures. A significant positive relationship existed between the second gum picking and the total gum yield. The second gum picking seems to be a decisive factor in gum production and could be used as an indicator for the prediction of the total gum yield. Soil organic carbon, N, P and K contents were not increased by agroforestry as compared to the initial levels. Soil OC was not increased by agroforestry as compared to sole cropping. There was no evidence that P increased in the topsoil as the agroforestry plantations aged. At a stocking density of 400 trees ha⁻¹ (5 × 5 m spacing), A. senegal accumulated in its biomass a total of 18.0, 1.21, 7.8 and 972 kg ha⁻¹ of N, P, K and OC, respectively. Agroforestry contributed ca. 217 and 1500 kg ha⁻¹ of K and OC, respectively, to the top 25-cm of soil during the first four years of intercropping.     

Structure and species diversity of subtropical evergreen broad-leaved forest in northern Okinawa Island, Japan

The structure and tree species diversity of a subtropical evergreen broad-leaved forest in northern Okinawa Island, Japan, were studied. Enumeration of the six sampling plots revealed an average density of 5,580 individuals with DBH≧3.0 cm/ha, having an average basal area of 55 m². The large-size trees of DBH≧20 cm contributed 10% of the total individuals, and 49% of the total basal area. The forest showed a high diversity of tree species, which is comparable to some tropical rain forests. A total of 54 over-story species of 24 families and a total of 63 understory species of 26 families were identified in the six sampling plots. Fagaceae and Theaceae were the most important families;Castanopsis sieboldii, Schima wallichii andDistylium racemosum were the most important species. The diversity index and equitability index of species were 4.15 and 0.72 for the overstory plots, and 4.72 and 0.79 for the understory subplots, respectively. The diversity index for the overstory was significantly correlated to the total basal area of trees over 20 cm DBH (p<0.05) and the importance value ofC. sieboldii (p<0.001), while for understory, the diversity index was not correlated to the structural parameters (allp>0.16). The size distribution pattern and age structure indicated differences in regeneration strategies for canopy dominants. In population dynamics of the succession process,C. sieboldii andD. racemosum were self-maintaining types, andS. wallichii was a gap- or opening-dependent type. This study was made possible by support from the Japanese Ministry of Education, Sciences, Sports and Culture, which provided a Monbusho scholarship to X.N. Xu.     

Dehydrogenase activity and VAM fungi in tree-rhizosphere of agroforestry systems in Indian arid zone

Biological activity in tree rhizosphere and association of VAM fungi with tree-roots could be used as selection criteria for agroforestry trees in arid ecosystems. Dehydrogenase activity and VAM fungi association in rhizosphere of six agroforestry trees (Azadirachta indica, Acacia tortilis, Eucalyptus camaldulensis, Prosopis cineraria and Tecomella undulata) were studied under irrigated and rainfed conditions in the arid zone of India. Higher dehydrogenase activity (9.5 to 16.8∼p kat g soil⁻¹), root colonization (58.3 to 68.5%) and spore density (132.5 to 234.7 spores 100 g soil⁻¹) were observed in tree rhizosphere as compared to that in non-rhizosphere (7.4, 37.7 and 44.4). Irrigation had increased dehydrogenase activity by 22.1% while it reduced root colonization and spore density by 14.2% and 16.2%, respectively. Trees of A. indica had registered maximum growth while E. camaldulensis the least. Findings suggest that selection of A. nilotica, A. indica, and T. undulata for plantations of agroforestry in arid region would reduce the risk and ensure sustainability of the agroforestry system.     

Tree Culture of Smallholder Farmers Practicing Agroforestry in Gunung Salak Valley,West Java,Indonesia

This paper investigates the types of agroforestry system that exist in Gunung Salak Valley, West Java, Indonesia in order to characterize the differences in their basic structure and associated crop plant diversity. Data were collected through rapid rural appraisal, field observation and focus groups, followed by household survey of a sample of 20 agroforestry farmers. Five main agroforestry systems (homegardens, fruit tree system, timber tree system, mixed fruit–timber system, and cropping in the forest understory) exist in the study area, and all of them exhibit a noticeable diversity in terms of both species composition and utilization. Products from farming accounted for an average 24 % of household income. They comprised agroforestry products which contributed IDR 3.25 million/year and other agricultural products contributing IDR 1.66 million/year. The observed agroforestry systems include not only a form of forest dominated by ‘cultivated trees’, but also an anthropogenic vegetation formation derived from agricultural antecedents. In land-use classifications agroforestry systems are not recognized as forestry, but like forests they provide tree products and services. Classification will always be disfunctional if a binary system is applied, thus a more sophisticated approach should be adopted that incorporates the economic and environmental characteristics of a wider range of systems.