Watershed responses to Amazon soya bean cropland expansion and intensification

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Neill, Christopher ; Coe, Michael T. ; Riskin, Shelby H. ; Krusche, Alex V. ; Elsenbeer, Helmut ; Macedo, Marcia N. ; McHorney, Richard ; Lefebvre, Paul ; Davidson, Eric A. ; Scheffler, Raphael ; Figueira, Adelaine Michela e Silva ; Porder, Stephen ; Deegan, Linda A.

• Tipo de documento: Artigo Científico
• Fonte: PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES; v. 368, n. 1619, p. 7-pg., 2013-06-05.

Resumo

The expansion and intensification of soya bean agriculture in southeastern Amazonia can alter watershed hydrology and biogeochemistry by changing the land cover, water balance and nutrient inputs. Several new insights on the responses of watershed hydrology and biogeochemistry to deforestation in Mato Grosso have emerged from recent intensive field campaigns in this region. Because of reduced evapotranspiration, total water export increases threefold to fourfold in soya bean watersheds compared with forest. However, the deep and highly permeable soils on the broad plateaus on which much of the soya bean cultivation has expanded buffer small soya bean watersheds against increased stormflows. Concentrations of nitrate and phosphate do not differ between forest or soya bean watersheds because fixation of phosphorus fertilizer by iron and aluminium oxides and anion exchange of nitrate in deep soils restrict nutrient movement. Despite resistance to biogeochemical change, streams in soya bean watersheds have higher temperatures caused by impoundments and reduction of bordering riparian forest. In larger rivers, increased water flow, current velocities and sediment flux following deforestation can reshape stream morphology, suggesting that cumulative impacts of deforestation in small watersheds will occur at larger scales. (AU)

• Processo FAPESP: 08/58089-9 - The role of rivers on the regional carbon cycle
• Beneficiário: Maria Victoria Ramos Ballester
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático