Managing tradeoffs and synergies among biodiversity’s multiple dimensions

Background/Question/Methods

Our understanding of how to manage biodiversity is clouded by our weak grasp of its dimensions. Biodiversity is often simplified in management decisions, reduced to a few metrics that reflect only a subset of the reasons for why we care about its conservation. While we do know that biodiversity is valued for many reasons, we rarely consider tradeoffs between potentially competing dimensions of biodiversity. Here we develop the first typology for identifying tradeoffs and synergies among biodiversity’s dimensions. We then quantified indicators that assess how agricultural land management affects each dimension of biodiversity, using a network of 18 intensively studied field sites within tropical forest patches, nature reserves, and agriculture fields in southern Costa Rica. Specifically, we quantified indicators of bird biodiversity in six dimensions: global variety, local variety, evolution, naturalness, life-support systems, and social benefits. While our analysis focuses on bird communities, our approach could be applied to any taxa.

Results/Conclusions

We found that agriculture maintained local diversity and critical ecological processes like pest control, pollination, and seed dispersal on par with reserves; however, rare, endemic, elevation-restricted, and evolutionary-unique species declined in agricultural systems. We also identified potential management tradeoffs; for example, interventions designed to conserve rapidly diversifying lineages would likely cause declines in rare, endemic, and forest-affiliated species. Despite these tradeoffs, we found that conserving forest in farmland enhanced most dimensions at minimal expense to others. More broadly, our results demonstrate how considering multidimensionality can identify potential tradeoffs among biodiversity dimensions, as well as strategies for improving multiple dimensions at once. In agricultural landscapes where improving rural livelihoods and local economies are critical, ensuring that multiple dimensions of biodiversity improve could garner more widespread support for conservation interventions. Admitting the complexity and multidimensionality of biodiversity will undoubtedly complicate conservation planning. However, it would also likely yield the synergistic outcomes for people and nature that are essential for pursuing conservation in human-dominated landscapes.