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.     

Organic matter pools and nutrient cycling in different coffee production systems in the Brazilian Cerrado

Agroforestry and organic systems have been used to reduce the negative effects that conventional coffee cultivation has on soils. In this work, ¹³C-CPMAS-NMR, Fourier transform infrared spectroscopy, elemental composition, classical humus fractionation and the soil fertility status were used to evaluate the impact of these three systems on a Latosol from the Brazilian Cerrado. Continuous input of tree residues promoted changes to the soil organic matter with increase in total organic carbon, humic acids (HA) and light organic matter, mainly in the topsoil. Available P and cation exchange capacity were also increased and the acidity status decreased in the agroforestry system. Moreover, HA from the agroforestry were enriched in O-alkyl C, O-di-alkyl C and alkyl C groups and the organic system resulted in HA richer in carboxyl groups. The conventional system resulted in greater aromatic and methoxyl participation, and lower phenol groups. HA from the agroforestry system were richer in easily degradable structures and the chemical fractionation demonstrated a decrease in both recalcitrant fractions, allowing for a more conservative and sustainable management of soil fertility. The modifications were not as evident in the organic system, probably due to the low organic fertilizer input.     

Potential of indigenous multistrata agroforests for maintaining native floristic diversity in the south-eastern Rift Valley escarpment, Ethiopia

Most studies undertaken in the field of agroforestry have focussed on system design, soil fertility management, and system interactions. Less emphasis has been placed on biodiversity aspects. The aim of this study is to investigate the potential of indigenous, multistrata agroforests for maintaining native woody species diversity in the south-eastern Rift Valley escarpment, Ethiopia. A total of 60 farms, representing three agroforest types (enset-AF, enset-coffee-AF and fruit-coffee-AF), were randomly selected along altitudinal gradients. Enset (Ensete ventricosum) is a perennial, herbaceous monocarpic banana-like plant which serves as a food plant in Ethiopia. The three agroforests are results of the domestication of natural forests and intensification of the landuse systems centuries ago. Sample-based assessment protocols were employed to place sample quadrats and to measure all individuals in the quadrats. A total of 58 woody species, belonging to 49 genera and 30 families, was recorded. Of all woody species identified, 86% were native. The highest proportion of native woody species was recorded in enset-AF (92%), followed by enset-coffee-AF (89%) and fruit-coffee-AF (82%). Among native tree species, Millettia ferruginea and Cordia africana were the most widespread. In all, 22 native woody species were recorded as of interest for conservation, acccording to IUCN Red lists and local criteria. Among them, Pygeum africanum and Rhus glutinosa were categorised as vulnerable in the wild, and in need of conservation priority. The introduction of non-native fruit trees in agroforests can be a threat to maintenance of native woody species. Management strategies favoring enset and coffee will also put other native tree species at risk. A smaller number of native woody species was recorded in fruit-coffee-AF, but a higher mean basal area and stem number. The mean basal area and stem number ranged from 5.4?±?0.5 to 11.7?±?1.0?m^2?ha^?1 and 625?±?84 to 1,505?±?142 stems?ha^?1, respectively. Altitude explained 68 and 71% of the variation in species richness and abundance, respectively. Finally, it is concluded that recognition of the indigenous agroforestry system as an option for maintaining native woody species should be given more attention, to counteract the local threat of these species from the wild.     

Fertilizer type and species composition affect leachate nutrient concentrations in coffee agroecosystems

Intensification of coffee (Coffea arabica) production is associated with increases in inorganic fertilizer application and decreases in species diversity. Both the use of organic fertilizers and the incorporation of trees on farms can, in theory, reduce nutrient loss in comparison with intensified practices. To test this, we measured nutrient concentrations in leachate at 15 and 100 cm depths on working farms. We examined (1) organically managed coffee agroforests (38 kg N ha^?1 year^?1; n = 4), (2) conventionally managed coffee agroforests (96 kg N ha^?1 year^?1; n = 4), and (3) one conventionally managed monoculture coffee farm in Costa Rica (300 kg N ha^?1 year^?1). Concentrations of nitrate (NO₃ ^?-N) and phosphate (PO₄ ^3?-P) were higher in the monoculture compared to agroforests at both depths. Nitrate concentrations were higher in conventional than organic agroforests at 15 cm only. Soil solutions collected under nitrogen (N)-fixing Erythrina poeppigiana had elevated NO₃ ^?-N concentrations at 15 cm compared to Musa acuminata (banana) or Coffea. Total soil N and carbon (C) were also higher under Erythrina. This research shows that both fertilizer type and species affect concentrations of N and P in leachate in coffee agroecosystems.     

Shade trees: a determinant to the relative success of organic versus conventional coffee production

Greater understanding of the influences on long-term coffee productivity are needed to develop systems that are profitable, while maximizing ecosystem services and lowering negative environmental impacts. We examine a long-term experiment (15 years) established in Costa Rica in 2000 and compare intensive conventional (IC) coffee production under full sun with 19 agroforestry systems combining timber and service tree species with contrasting characteristics, with conventional and organic managements of different intensities. We assessed productivity through coffee yield and coffee morphological characteristics. IC had the highest productivity but had the highest yield bienniality; in the agroforestry systems productivity was similar for moderate conventional (MC) and intensive organic (IO) treatments (yield 5.3 vs. 5.0 t ha^?1 year^?1). Significantly lower yields were observed under shade than full sun, but coffee morphology was similar. Low input organic production (LO) declined to zero under the shade of the non-legume timber tree Terminalia amazonia but when legume tree species were chosen (Erythrina poepiggiana, Chloroleucon eurycyclum) LO coffee yield was not significantly different than for IO. For the first 6 years, coffee yield was higher under the shade of timber trees (Chloroleucon and Terminalia), while in the subsequent 7 years, Erythrina systems were more productive; presumably this is due to lower shade covers. If IC full sun plantations are not affordable or desired in the future, organic production is an interesting alternative with similar productivity to MC management and in LO systems incorporation of legume tree species is shown to be essential.     

Strategies and economics of farming systems with coffee in the Atlantic Rainforest Biome

In the Zona da Mata of Minas Gerais State, Brazil, family farmers are adjusting to agroecological principles to reconcile sustainable agriculture, livelihood improvements and biodiversity conservation. Starting in 1993, experimentation with coffee agroforestry was gradually initiated on an increasing number of farms (37 in total), resulting in the simultaneous management of sun coffee (SC) and agroforestry coffee (AF) plots. We aimed (1) to identify factors that determine the farmers’ selection of trees used in AF; (2) to describe the agroecological farms in transition; and (3) to perform an economic comparison between AF and SC. These objectives were addressed by combining data from botanical surveys in 1993/1994 and 2007, by interviews with farmers and by detailed data on the production value and costs of labour and material inputs. The results showed considerable diversity in farming strategies and management among the farmers. Early adopters of AF had diversified towards production of different marketable products. The use of native trees in AF for this purpose, and for restoration of soil fertility (e.g., leguminous trees), had increased since the start of the experiments, while exotic tree species were eliminated. Over a period of 12 years AF was more profitable than SC due to the production of a diversity of agricultural goods, despite somewhat higher establishment costs. Other ecosystem services delivered by AF, such as biodiversity and cultural services are currently not valorized. Payment schemes for environmental services could further improve the economic benefits of AF for family farmers and alleviate establishment and learning costs.     

Assessment of tree diversity and above-ground biomass in coffee agroforest dominated tropical landscape of India's Central Western Ghats

The purpose of this study was to quantify the changes in tree diversity and above-ground biomass associated with six land-use types in Kodagu district of India's Western Ghats. We collected data on species richness,composition and above-ground biomass(AGB) of trees,shrubs and herbs from 96 sample plots of 0.1 ha. Totals of83 species from 26 families were recorded across the landuses. Tree species richness, diversity and composition were significantly higher in evergreen forest(EGF) than in other land-uses. Similarly, stem density and basal area were greater in EGF compared to other land-uses. Detrended correspondence analysis(DCA) yielded three distinct groups along the land-use intensities and rainfall gradient on the first and second axes, respectively. The first DCA axis accounted for 45% and second axis for 35% of the total variation in species composition. Together the first two axes accounted for over 2/3 of the variation in species composition across land-use types. Across the land-uses,AGB ranged from 58.6 Mg ha-1 in rubber plantation to327.3 Mg ha-1 in evergreen forest. Our results showed that species diversity and AGB were negatively impacted bythe land-use changes. We found that coffee agroforests resembled natural forest and mixed species plantation in terms of tree diversity and biomass production, suggesting that traditional coffee farms can help to protect tree species, sustain smallholder production and offer opportunities for conservation of biodiversity and climate change mitigation.     

Short-term changes in the soil carbon stocks of young oil palm-based agroforestry systems in the eastern Amazon

The current expansion of the oil palm (Elaeis guineensis Jacq.) in the Brazilian Amazon has mainly occurred within smallholder agricultural and degraded areas. Under the social and environmental scenarios associated with these areas, oil palm-based agroforestry systems represent a potentially sustainable method of expanding the crop. The capacity of such systems to store carbon (C) in the soil is an important ecosystem service that is currently not well understood. Here, we quantified the spatial variation of soil C stocks in young (2.5-year-old) oil palm-based agroforestry systems with contrasting species diversity (high vs. low); both systems were compared with a ~10-year-old forest regrowth site and a 9-year-old traditional agroforestry system. The oil palm-based agroforestry system consisted of series of double rows of oil palm and strips of various herbaceous, shrub, and tree species. The mean (±standard error) soil C stocks at 0–50 cm depth were significantly higher in the low (91.8 ± 3.1 Mg C ha^?1) and high (87.6 ± 3.3 Mg C ha^?1) species diversity oil palm-based agroforestry systems than in the forest regrowth (71.0 ± 2.4 Mg C ha^?1) and traditional agroforestry (68.4 ± 4.9 Mg C ha^?1) sites. In general, no clear spatial pattern of soil C stocks could be identified in the oil palm-based agroforestry systems. The significant difference in soil carbon between the oil palm area (under oil palm: 12.7 ± 2.3 Mg C ha^?1 and between oil palm: 10.6 ± 0.5 Mg C ha^?1) and the strip area (17.0 ± 1.4 Mg C ha^?1) at 0–5 cm depth very likely reflects the high input of organic fertilizer in the strip area of the high species diversity oil palm-based agroforestry system treatment. Overall, our results indicate a high level of early net accumulation of soil C in the oil palm-based agroforestry systems (6.6–8.3 Mg C ha^?1 year^?1) that likely reflects the combination of fire-free land preparation, organic fertilization, and the input of plant residues from pruning and weeding.     

Coffee agroecosystem performance under full sun, shade, conventional and organic management regimes in Central America

Changes in coffee economics are leading producers to reduce agrochemical use and increase the use of shade. Research is needed on how to balance the competition from shade trees with the provision of ecological services to the coffee. In 2000, long-term coffee experiments were established in Costa Rica and Nicaragua to compare coffee agroecosystem performance under full sun, legume and non-legume shade types, and intensive and moderate conventional and organic inputs. Coffee yield from intensive organic production was not significantly different from intensive conventional in Nicaragua, but in Costa Rica it was lower during three of the six harvests. Full sun coffee production over 6 years was greater than shaded coffee in Costa Rica (61.8 vs. 44.7 t ha^?1, P = 0.0002). In Nicaragua, full sun coffee production over 5 years (32.1 t ha^?1) was equal to coffee with shade that included Tabebuia rosea (Bertol.) DC., (27?C30 t ha^?1) and both were more productive (P = 0.03) than coffee shaded with Inga laurina (Sw.) Willd. (21.6 t ha^?1). Moderate input organic production was significantly lower than other managements under all shade types, except in the presence of Erythrina poepiggina (Walp.) O.F. Cook. Inga and Erythrina had greater basal area and nutrient recycling from prunings than other shade species. Intensive organic production increased soil pH and P, and had higher K compared to moderate conventional. Although legume shade trees potentially provide ecological services to associated coffee, this depends on management of the competition from those same trees.     

Nature vs. nurture: managing relationships between forests,agroforestry and wild biodiversity

Many agroforestry systems are found in places that otherwise would be appropriate for natural forests, and often have replaced them. Humans have had a profound influence on forests virtually everywhere they both are found. Thus ‘natural’ defined as ‘without human influence’ is a hypothetical construct, though one that has assumed mythological value among many conservationists. Biodiversity is a forest value that does not carry a market price. It is the foundation, however, upon which productive systems depend. The relationship between agroforestry and the wild biodiversity contained in more natural forests is a complicated one, depending on the composition of the agroforestry system itself and the way it is managed. Complex forest gardens are more supportive of biodiversity than monocrop systems, shade coffee more than sun coffee, and systems using native plants tend to be more biologically diverse. Nonnative plants, especially potentially invasive alien species, threaten biodiversity and need to be avoided. The relationship between forests, agroforestry and wild biodiversity can be made most productive through applying adaptive management approaches that incorporate ongoing research and monitoring in order to feed information back into the management system. Maintaining diversity in approaches to management of agroforestry systems will provide humanity with the widest range of options for adapting to changing conditions. Clear government policy frameworks are needed that support alliances among the many interest groups involved in forest biodiversity.

     

Diversity, composition and density of trees and shrubs in agroforestry homegardens in Southern Ethiopia

Diversity of trees and shrubs in agricultural systems contributes to provision of wood and non-wood products, and protects the environment, thereby, enhancing socioeconomic and ecological sustainability of the systems. This study characterizes the diversity, density and composition of trees in the agroforestry homegardens of Sidama Zone, Southern Ethiopia, and analyses physical and socioeconomic factors influencing diversity and composition of trees in the systems. A total of 144 homegardens were surveyed from 12 sites. In total, 120 species of trees and shrubs were recorded of which, 74.2 % were native to the area. The mean number of tree species per farm was 21. Density of trees varied between sites with mean values ranging from 86 to 1,082, and the overall average was 475 trees ha^?1. Four different crop-based enset (Enset ventricosum (Welw.) Cheesman)-coffee homegarden types were recognized and they differed not only in the composition of major crops but also in the diversity, density and composition of trees. The composition, diversity and density of trees is influenced by physical and socioeconomic factors. The major physical factors were geographical distance between sites and differences in altitude of farms. The most important socioeconomic factors were farm size and access to roads. Tree species richness and density increased with farm size. Increased road access facilitated marketing opportunities to agricultural products including trees, and lead to a decline in the basic components of the system, enset, coffee and trees. In the road-access sites, the native trees have also been largely replaced with fast growing exotic species, mainly eucalypts. The decrease in diversity of trees and perennial components of the system, and its gradual replacement with new cash and annual food crops could jeopardize the integrity and complexity of the system, which has been responsible for its sustenance.     

Cooperative management and its effects on shade tree diversity,soil properties and ecosystem services of coffee plantations in western El Salvador

We compared how management approaches affected shade tree diversity, soil properties, and provisioning and carbon sequestration ecosystem services in three shade coffee cooperatives. Collectively managed cooperatives utilized less diverse shade, and pruned coffee and shade trees more intensively, than individual farms. Soil properties showed significant differences among the cooperatives, with the following properties contributing to differentiation: N, pH, P, K, and Ca. Higher tree richness was associated with higher soil pH, CEC, Ca, and Mg, and lower K. Higher tree densities were associated with lower N, K, and organic matter. Although we found differences in the incidence of provisioning services (e.g., fruit), all plantations generated products other than coffee. No differences were observed between C-stocks. The history and institutional arrangements of cooperatives can influence management approaches, which affect ecosystem properties and services. Our study corroborates that interdisciplinary investigations are essential to understand the socio-ecological context of tropical shade coffee landscapes.     

Carbon, nitrogen, organic phosphorus, microbial biomass and N mineralization in soils under cacao agroforestry systems in Bahia, Brazil

Large amounts of plant litter deposited in cacao agroforestry systems play a key role in nutrient cycling. Organic matter, nitrogen and phosphorus cycling and microbial biomass were investigated in cacao agroforestry systems on Latosols and Cambisols in Bahia, Brazil. The objective of this study was to characterize the microbial C and N, mineralizable N and organic P in two soil orders under three types of cacao agroforestry systems and an adjacent natural forest in Bahia, Brazil and also to evaluate the relationship between P fractions, microbial biomass and mineralized N with other soil attributes. Overall, the average stocks of organic C, total N and total organic P across all systems for 0?C50?cm soil depth were 89,072, 8,838 and 790?kg?ha^?1, respectively. At this soil depth the average stock of labile organic P was 55.5?kg?ha^?1. For 0?C10?cm soil depth, there were large amounts of microbial biomass C (mean of 286?kg?ha^?1), microbial biomass N (mean of 168?kg?ha^?1) and mineralizable N (mean of 79?kg?ha^?1). Organic P (total and labile) was negatively related to organic C, reflecting that the dynamics of organic P in these cacao agroforestry systems are not directly associated with organic C dynamics in soils, in contrast to the dynamics of N. Furthermore, the amounts of soil microbial biomass, mineralizable N, and organic P could be relevant for cacao nutrition, considering the low amount of N and P exported in cacao seeds.     

Changes in arboreal ant populations following pruning of coffee shade-treesin Chiapas,Mexico

Reducing or eliminating shade cover in coffee (Coffea arabica L.) agroforestry systems affects fungal disease and pest outbreaks, coffee yields, and can result in biodiversity loss of important predators, such as ants. Less dramatic changes in shade structure or composition may also affect ants. Shade tree pruning, a common management practice in shaded coffee systems, has unknown consequences for ant communities. The effects of pruning on arboreal ant communities were investigated by measuring ant abundance, distribution, and species richness in the short (1 week) and long-term (6 months) after shade tree pruning in one 25×50 m plot. Shade tree pruning significantly affected the distribution and abundance of two of the most common ant species (Azteca instabilis F. Smith and Camponotus senex textor Forel), and in general did not affect other ants. After pruning, C. senex textor ants were 80% more abundant on coffee plants and shade trees, whereas A. instabilis abundance dropped by 40% on coffee plants and 73% on shade trees after pruning. Additionally, C. senex textor were significantly more widespread, whereas A. instabilis distributions were more restricted. The effects of pruning were strong over the short-term, but were not evident over the long-term. Shade tree pruning did not affect ant diversity. Thus shade tree pruning largely affected certain aspects of arboreal ant communities in one coffee agroforestry system, with important implications for biological control.     

Growing woody biomass for bioenergy in a tree-based intercropping system in southern Ontario, Canada

During the spring of 2006, three willow varieties (SV1, SX67 and 9882-41) were established on marginal land in an agroforestry tree-intercropping arrangement where plots of short rotation willows were planted between rows (spaced 15?m apart) of 21-year-old mixed tree species. As a control, the same varieties were established on an adjacent piece of land without established trees (conventional willow system). This study investigated the magnitude of carbon pools, fine root and leaf biomass inputs and clone yields in both the tree-based intercropping (agroforestry) and conventional monocropping systems. Willow biomass yield was significantly higher in the agroforestry field (4.86?odt?ha^?1?y^?1) compared to the conventional field (3.02?odt?ha^?1?y^?1). In both fields, varieties SV1 and SX67 produced higher yields than the variety 9882-41. Willow fine root biomass in the top 20?cm of soil was significantly higher in the intercropping system (3,062?kg?ha^?1) than in the conventional system (2,536?kg?ha^?1). Differences in fine root biomass between clones were similar to that observed for differences in biomass yield: SV1?>?SX67?>?9882-41. Leaf input was higher in the intercropping system (1,961?kg?ha^?1) than in the conventional system (1,673?kg?ha^?1). Clonal differences in leaf inputs followed the same trends as those for root biomass and yield: SV1?>?SX67?>?9882-41. Soil organic carbon was significantly higher in the agroforestry field (1.94?%) than in the conventional field (1.82?%). A significant difference in soil organic carbon was found between the three clones: soils under clone 9882-41 had the lowest soil organic carbon at 1.80?%.     

Changes in soil organic carbon fractions in a tropical Acrisol as influenced by the addition of different residue materials

Residues of Leucaena (Leucaena leucocephala (L), Senna siamea (S) and maize stover (M) were tested to evaluate their effect on soil organic matter accumulation and composition under sub-humid tropical conditions. On an Imperata cylindrica (I) dominated grass fallow, a total amount of 30?Mg?ha^?1 DM were applied within 18?months. Two months after the last application, changes in the light and heavy soil organic carbon fraction (LF and HF) and in the total soil organic carbon content (LF?+?HF) in the topsoil were observed. All organic materials increased the proportion of the LF fraction in the soil significantly. The increase in HF was 39 to 51% of the increase in total organic carbon, depending on the source of the organic material. The potential of the tested organic materials to increase total soil organic carbon content (including all soil organic carbon fractions) was in the order L?>?S?>?M?>?I, whereas the order of increase of the HF fraction was L?=?S?>?I?>?M. Cation exchange capacity of the newly formed heavy soil organic carbon was highest with L and lowest with M. Ranking of the transformation efficiency of applied plant residues into the heavy soil organic carbon fraction was I?>?L?=?S?>?M. Transformation efficiency of the residues could neither be explained by lignin nor lignin/N ratio, but rather by extractable polyphenols (Folin?CDenis extraction). The results show that accumulation of the HF fraction in tropical soils is feasible through the application of large quantities of plant residues, but depends strongly on the composition of the applied materials.     

Geostatistical modeling of the spatial variability of coffee fine roots under Erythrina shade trees and contrasting soil management

Spatial relationships between root length density of Coffea arabica (coffee RLD) and soil nutrient- related factors at plot scale in a coffee- Erythrina poeppigiana system was studied by geostatistics. In a 24 × 29 m area, (organic and conventional management), coffee and Erythrina fine roots and soil chemical properties were sampled on an irregular grid in the topsoil. A factor analysis explained 83 % of the total variation of the soil attributes. Soil factors were identified: Chemical fertility (CF), Micronutrients, Organic matter, and Acidity (Ac). Based on the spherical model, all the attributes presented a strong spatial structure. The scale of spatial correlation for CF was lesser than for Ac, but similar to coffee RLD. Erythrina RLD had a short-range variation. Patchy areas of high spots of coffee RLD were greater in organic plot. Cross-semivariogram analysis estimated a correlation between soil factors and coffee RLD over a scale of 5.50 m; but 4.23 m with Erythrina RLD. Nutrients linked to P, Zn, exchangeable bases and acidity soil affected the scale of spatial aggregation pattern of coffee RLD. The spatial response of coffee RLD suggests a differential nutrient uptake strategy for acquiring soil nutrients induced by the quality of organic and inorganic fertilizer inputs. The fact that coffee RLD had higher scale of spatial variation than Erythrina RLD and a negative spatial correlation indicate that pruned Erythrina trees are not so competitive for acquiring shared nutrients in an agroforestry system.     

Simulation of carbon pool changes in woodlots in eastern Zambia using the CO2FIX model

Agroforestry systems have the potential to contribute significantly to climate change mitigation and adaptation. However, data on tree and soil organic carbon (SOC) pools for most agroforestry systems are lacking because reliable methods for estimating ecosystem carbon (C) pools are scarce. This study quantified the effects of five Leucaena species (L. leucocephala, L. macrophylla, L. diversifolia, L. collinsii and L. pulverulenta) on vegetal and soil C stocks and on mean annual increment (MAI) in aboveground tree C stocks. Specifically, it tested the validity of the CO2FIX model using empirical data from 7?year-old woodlots at Msekera, Zambia, and assessed the impact of converting a degraded agricultural ecosystem to woodlots on C stocks. Measured above- and below-ground tree C stocks and MAI of aboveground biomass differed significantly among the Leucaena species. Measured stem and total aboveground tree C stocks in seven-year old woodlots ranged from 17.1 to 29.2 and from 24.5 to 55.9?Mg?ha^?1, respectively. Measured SOC stocks at 0?C200?cm depth in Leucaena stands ranged from 106.9 (L. diversifolia) to 186.0?Mg?ha^?1 (L. leucocephala). Modeled stem and branch C stocks closely matched measured stocks, but the soil module of CO2FIX did not predict the soil C. The soil C data are inconclusive at this stage. We recommend that a fractionation and a soil aggregate hierarchy study backed by C dating is carried out to explain soil C dynamics in these soils. However, the model can be used only for estimating changes in aboveground tree C stocks in woodlots until soil C module is proven to predict SOC stocks.     

Traditional agroforestry systems and biodiversity conservation in Benin (West Africa)

In the past, the conservation of biodiversity has been mostly understood in terms of the management of protected areas and natural forests, ignoring the possible role of farm areas and the ways through which rural communities have promoted biodiversity in their subsistence agricultural production systems. The present study focused on the floristic diversity within traditional agroforestry parkland systems around the Pendjari Biosphere Reserve in Benin and showed the diversity of tree species in the area as well as socio-economic factors which affect the practice of this farming system. We used questionnaires and interviewed a total of 118 households to collect data. Respondents were interviewed on their farms and during the interview; we inventoried the number of tree on the farm and determined the farm size. Twenty-one tree species belonging to 14 botanical families were recorded during the surveys and the average stand density of the woody component of farmlands was 7.97 ± 5.43 stems/ha. A number of both native and exotic tree species occurred in the parkland agroforestry systems with dominance of indigenous tree species. Species richness varied with the size of household where households with small land holding conserve more tree species in their field than households with large land holdings. 64% of households surveyed were making deliberate efforts to plant tree species on their farmlands. The most important reasons which determined household ambitions to conserve woody species on farmland were tree products contribution to food and medicine. Results also showed that respondents who noticed that trees were decreasing in the wild conserve more tree species on their farmlands. This research highlights the role of traditional agroforestry practices to support tree species richness and provides evidence of the farms’ role as biodiversity reservoirs.     

Agroforestry systems reduce invasive species richness and diversity in the surroundings of protected areas

The Serra do Brigadeiro State Park (PESB) is one of the largest fragments of Brazilian Atlantic Rainforest, and it is relevant for native species conservation. However, monocultures settled around the Park resulted in extensive open areas that facilitate the establishment of alien species on the PESB perimeter, which may threaten native species conservation therein, since biological invasion is the second main cause of global biodiversity loss. In this region, there are also farmers planting agroforestry systems (AFS), characterized by tree-based intercropping, which are structurally more similar to the Atlantic Rainforest reminiscent fragments present in the region and may limit local occurrence of potentially invasive exotic weeds for several reasons, such as the high levels of shade provided by trees, the groundcover that result from loss of tree leaves and the increased competition for belowground resources. This study aimed to test whether AFS limit exotic species establishment when compared to monoculture systems. Accordingly, three coffee monocultures and three agroforestry coffee plantations around the PESB were studied. In each of the six study areas, 30 plots of 1 m² were established between the lines of coffee plantation, where all species present were surveyed. In both treatments, rarefaction curves were constructed to evaluate native and exotic richness, and diversity of these two categories was estimated through Simpson index inverse (1/D). All 13 sampled exotic species were present in monocultures, but only three of them occurred in AFS. Besides, alien diversity in monocultures (\(1/D\) = 2.173 ± 0.011) was significantly higher than in AFS (\(1/D\) = 1.031 ± 0.001). Such changes in alien plant community between land-use show that AFSs limit invasive species establishment. Therefore, when planted around protected areas, AFS may contribute to the control of biological invasions and to biodiversity conservation.