@article{NeillCoeRiskinetal.2013, author = {Neill, Christopher and Coe, Michael T. and Riskin, Shelby H. and Krusche, Alex V. and Elsenbeer, Helmut and Macedo, Marcia N. and McHorney, Richard and Lefebvre, Paul and Davidson, Eric A. and Scheffler, Raphael and Figueira, Adelaine Michela e Silva and Porder, Stephen and Deegan, Linda A.}, title = {Watershed responses to Amazon soya bean cropland expansion and intensification}, series = {Philosophical transactions of the Royal Society of London : B, Biological sciences}, volume = {368}, journal = {Philosophical transactions of the Royal Society of London : B, Biological sciences}, number = {1619}, publisher = {Royal Society}, address = {London}, issn = {0962-8436}, doi = {10.1098/rstb.2012.0425}, pages = {7}, year = {2013}, abstract = {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.}, language = {en} } @article{HayhoeNeillPorderetal.2011, author = {Hayhoe, Shelby J. and Neill, Christopher and Porder, Stephen and McHorney, Richard and Lefebvre, Paul and Coe, Michael T. and Elsenbeer, Helmut and Krusche, Alex V.}, title = {Conversion to soy on the Amazonian agricultural frontier increases streamflow without affecting stormflow dynamics}, series = {Global change biology}, volume = {17}, journal = {Global change biology}, number = {5}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {1354-1013}, doi = {10.1111/j.1365-2486.2011.02392.x}, pages = {1821 -- 1833}, year = {2011}, abstract = {Large-scale soy agriculture in the southern Brazilian Amazon now rivals deforestation for pasture as the region's predominant form of land use change. Such landscape-level change can have substantial consequences for local and regional hydrology, but these effects remain relatively unstudied in this ecologically and economically important region. We examined how the conversion to soy agriculture influences water balances and stormflows using stream discharge (water yields) and the timing of discharge (stream hydrographs) in small (2.5-13.5 km2) forested and soy headwater watersheds in the Upper Xingu Watershed in the state of Mato Grosso, Brazil. We monitored water yield for 1 year in three forested and four soy watersheds. Mean daily water yields were approximately four times higher in soy than forested watersheds, and soy watersheds showed greater seasonal variability in discharge. The contribution of stormflows to annual streamflow in all streams was low (< 13\% of annual streamflow), and the contribution of stormflow to streamflow did not differ between land uses. If the increases in water yield observed in this study are typical, landscape-scale conversion to soy substantially alters water-balance, potentially altering the regional hydrology over large areas of the southern Amazon.}, language = {en} }