Lessons from land sharing: Predicting and sustaining biodiversity in tropical countryside

Background/Question/Methods

Growing demand for food, fuel, and fiber is driving the intensification and expansion of agricultural land through a corresponding displacement of native woodland, savanna, and shrubland. In the wake of this displacement, it is clear that farmland can support biodiversity through preservation of important ecosystem elements.  But how much biodiversity can be sustained, and with what tradeoffs for production, are open questions. Using a well-studied tropical, land sharing ecosystem in Costa Rica, we develop empirically based models for quantifying farmland’s ‘wildlife-friendliness’ for many taxa. 

Results/Conclusions

Some 80% of the 273 adequately sampled amphibian, bat, bird, non-flying mammal, and reptile species thrive in the landscape due to fine-scale countryside forest elements (ribbons of trees, typically of variable length and width) that weave through farmland along hilltops, valleys, rivers, roads, and property borders. Only 7% of adequately sampled vertebrate species were restricted to the 262-ha forest reserve and 15% were exclusively found in pasture or sun coffee plantations. Historical records for mammals and birds indicate that only 12 of the 537 species have gone locally extinct. We find that the proportion and configuration of countryside forest elements on farmland determines community compositions at taxon-specific spatial scales for tropical vertebrates (amphibians, bats, birds, non-flying mammals, and reptiles), arthropods (bees, butterflies, and moths), and herbaceous plants. Using these models, we theoretically explore how gradients of agricultural intensity (e.g. land sharing to land sparing ecosystem element configurations) and agricultural extent (e.g. total proportion of farmland) affect tropical biodiversity holistically. Our findings provide a basis for estimating and sustaining biodiversity in farming systems through managing native and semi-natural ecosystem elements at taxon-specific spatial scales. Moreover our results inform ecosystem service analyses, biodiversity action plans, and regional land use strategies.