Contribution of trees to the conservation of biodiversity and ecosystem services in agricultural landscapes

Abstract

The production of sufficient food for an increasing global population while conserving natural capital is a major challenge to humanity. Tree-mediated ecosystem services are recognized as key features of more sustainable agroecosystems but the strategic management of tree attributes for ecosystem service provision is poorly understood. Six agroforestry and tree cover transition studies, spanning tropical/subtropical forest zones in three continents, were synthesized to assess the contribution of tree cover to the conservation of biodiversity and ecosystem services. Loss of native earthworm populations resulted in 76% lower soil macroporosity when shade trees were absent in coffee agriculture. Increased tree cover contributed to 53% increase in tea crop yield, maintained 93% of crop pollinators found in the natural forest and, in combination with nearby forest fragments, contributed to as much as 86% lower incidence for coffee berry borer. In certain contexts, shade trees contributed to negative effects resulting from increases in abundance of white stem borer and lacebugs and resulted in 60% reduction of endangered tree species compared to forest. Managing trees for ecosystem services requires understanding which tree species to include and how to manage them for different socio-ecological contexts. This knowledge needs to be shared and translated into viable options with farming communities. ARTICLE HISTORY

The conservation value of cacao agroforestry for bird functional diversity in tropical agricultural landscapes

“…These environments show lower management intensity and, therefore, can harbor high species richness and greater habitat heterogeneity at the landscape scale (Bhagwat et al, ). Although agroforestry can indeed harbor greater diversity than monocultures (Barrios et al, ), studies have shown that these agrosystems may be associated with declines or changes in communities of forest specialists, plants, terrestrial invertebrates, and birds compared with surrounding forests (Barrios et al, ; Bhagwat et al, ; Van Bael, Bichier, Ochoa, & Greenberg, ). Therefore, these systems are not substitutes for intact forests but may contribute to species conservation at the landscape scale.…”

Is shadier better? The effect of agroforestry management on small mammal diversity

“…The rationale for a positive effect of vegetation complexity on species diversity is that the more complex habitats can offer greater niche diversity (August, ), increasing the diversity (not necessarily the quantity) of food resources and providing greater availability of shelter and structures used for displacement. Previous studies in coffee agroforests have demonstrated the reduction of faunal diversity with the decrease of shade tree diversity, another important source of resource diversity in these agroecosystems (Barrios et al, ; Caudill, Vaast, et al, ; Clough et al, ; Perfecto & Vandermeer, ). Although the assemblage structure did not respond to the complexity of the vegetation and resources abundance, some species are likely to be affected.…”

Applying the Aboveground-Belowground Interaction Concept in Agriculture: Spatio-Temporal Scales Matter

“…The spatial organization of landscapes has been shown to strongly affect aboveground biotic interactions. For arable cropping systems, semi-natural habitats are crucial for the persistence of populations of pollinators and natural enemies (Steffan-Dewenter et al, 2002;Kennedy et al, 2013;Barrios et al, 2018;Karp et al, 2018). Pollinators are largely dependent on semi-natural habitats outside agricultural fields for provision of alternative food resources and nesting sites (Kleijn et al, 2018b).…”

“…For pollinators, both the composition and configuration of crop and non-crop habitats is important to maintain effective communities (Barrios et al, 2018;Hass et al, 2018). Practices that increase flower-rich habitats can enhance pollinator conservation at the farm and landscape level (Dicks et al, 2015;Holland et al, 2015;Kleijn et al, 2018b).…”

“…Natural enemies also respond to landscape and local habitat structure in ways that influence pest suppression services (Bianchi et al, 2006). In general, as landscape complexity and the amount of non-crop habitat increase, the abundance and diversity of natural enemies and pest suppression may also increase (Chaplin-Kramer et al, 2011;Shackelford et al, 2013;Veres et al, 2013), but effects can be inconsistent (Barrios et al, 2018;Karp et al, 2018). Targeted interventions to specifically create and manage habitats that enhance natural enemies and pest suppression is promising (Gurr et al, 2017).…”