In the humid tropics, the rapid rate of deforestation has resulted in a race to protect remaining forest patches that are increasingly isolated within a rapidly expanding agricultural matrix. In these landscapes, a significant area consists of complex agro-forestry systems with high structural and functional plant diversity, providing critical resources for biodiversity conservation, such as food and habitat. Although not a substitute for natural forests, these anthropogenic habitats are gaining increasing conservation value as deforestation progresses. Shaded tree crops, such as cocoa, provide habitats for numerous forest dependent species of high conservation value and play a largely undocumented role in providing other ecological services. Following previous work on the botanical composition and structural complexity of cocoa agroforests in Talamanca (Costa Rica), we assessed if differences in the vegetation composition and structure of 36 cocoa agroforests could affect the wild diversity of small mammals, amphibians, reptiles, soil and litter macro-invertebrates and epiphytes found on cocoa trees and associated plants. Results show that Alpha-diversity is not affected by changes in vegetation structure and composition, except for amphibians and epiphytes found on cocoa trees. However, five taxa among eight showed distinct species composition patterns when compared among cocoa-based agroforestry clusters and with forest control. We showed that beta-diversity assessment enhances our understanding of the effect of management intensification on species composition and on habitat quality. The proper design of the shade component in these AFS will certainly play a key role in segregating wild species hosted in these systems and will open a new field of research for the intensification of both cocoa and associated productions in these highly diverse systems. (Résumé d'auteur

Brazil's riparian forests are continuously threatened by conversion into agricultural areas, causing not only degradation and loss of vegetation but also negative changes in soil properties and ecosystem services. In order to select vegetation and soil variables that are affected by degradation and to evaluate whether forest structure can be used as a proxy for soil ecosystem services, two watersheds in eastern Amazon were chosen as a study area in which four degradation levels were identified (very high, high, moderate and low), based on forest canopy openness and height. Vegetation structural characteristics, water infiltration rates, and soil properties were evaluated in 24, 1,000 m 2 permanent plots. Results indicated that forest degradation significantly reduced soil carbon, phosphorus, cation exchange capacity, silt proportion, total porosity, and water content as well as water infiltration rate. Vegetation structure was a good proxy for monitoring soil ecosystem services (i.e. regulation of water flow, erosion control and life-supporting). Tree height and basal area, as well as herb biomass, were identified as the best vegetation indicators for changes in soil properties that underlie ecosystem services. Application of this strategy may facilitate the monitoring and modeling of riparian forest ecosystem services across broader spatial scales, to help guide efficient restoration efforts and conservation policies.

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BackgroundRiparian forests provide ecosystem services that are essential for human well-being. The Pepital River is the main water supply for Alcântara (Brazil) and its forests are disappearing. This is affecting water volume and distribution in the region. Promoting forest restoration is imperative. In deprived regions, restoration success depends on the integration of ecology, livelihoods and traditional knowledge (TEK). In this study, an interdisciplinary research framework is proposed to design riparian forest restoration strategies based on ecological data, TEK and social needs.MethodsThis study takes place in a region presenting a complex history of human relocation and land tenure. Local populations from seven villages were surveyed to document livelihood (including ‘free-listing’ of agricultural crops and homegarden tree species). Additionally, their perceptions toward environmental changes were explored through semi-structured interviews (n = 79). Ethnobotanical information on forest species and their uses were assessed by local-specialists (n = 19). Remnants of conserved forests were surveyed to access ecological information on tree species (three plots of 1,000 m2). Results included descriptive statistics, frequency and Smith’s index of salience of the free-list results.ResultsThe local population depends primarily on slash-and-burn subsistence agriculture to meet their needs. Interviewees showed a strong empirical knowledge about the environmental problems of the river, and of their causes, consequences and potential solutions. Twenty-four tree species (dbh > 10 cm) were found at the reference sites. Tree density averaged 510 individuals per hectare (stdv = 91.6); and 12 species were considered the most abundant (density > 10ind/ha). There was a strong consensus among plant-specialists about the most important trees. The species lists from reference sites and plant-specialists presented an important convergence.ConclusionsSlash-and-burn agriculture is the main source of livelihood but also the main driver of forest degradation. Effective restoration approaches must transform problems into solutions by empowering local people. Successional agroforestry combining annual crops and trees may be a suitable transitional phase for restoration. The model must be designed collectively and include species of ecological, cultural, and socioeconomic value. In deprived communities of the Amazon, forest restoration must be a process that combines environmental and social gains.

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