GCB Bioenergy (May 2016)
Consequences of agroindustrial sugarcane production to freshwater biodiversity
Abstract
Abstract The environmental benefits of a broad‐scale adoption of biofuels are critically contingent on what current land uses will be converted for feedstock expansion and how converted land will be managed. We assessed the consequences of land use and land management for the agroindustrial production of sugarcane to the physical, chemical, and biological properties of freshwater systems. We surveyed 16 environmental variables and algae, tadpoles, predatory invertebrates, and fish in lentic water bodies distributed across a gradient in land‐use intensity ranging from seasonal Atlantic Forest and cerrado to pastures to sugarcane plantations in SE Brazil, the most important sugarcane‐producing region in the world. The gradient in land‐use intensity was not only an axis of native habitat loss but also of ecosystem productivity, as indicated by increased conductivity, turbidity, and phytoplankton biomass. Land use had a clear signal on community and metacommunity organization, with converted land being impoverished in biodiversity relative to native habitats. However, frequency of occurrence, density, biomass, and alpha diversity of tadpoles and their predators were not affected by land use. These results suggest that sugarcane fields function as habitat to a fraction of aquatic biodiversity. Within sugarcane fields, larger wetlands surrounded by buffer strips as required by law appeared comparatively buffered against land management practices and housed a disproportional fraction of animal biomass, likely acting as sources of migrants to other water bodies in the landscape. Conversion of pastures to sugarcane fields, suggested as a strategy to reduce competition for land with food production and biodiversity conservation, does not appear to have strong consequences to lentic freshwater systems, provided that wetlands and surrounding buffer strips are preserved. These observations emphasize the importance of enforcement of legislation regulating land use (i.e. the ‘Forest Code’) and certification systems verifying compliance and rewarding the voluntary adoption of better land management practices.
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