Watershed responses to Amazon soya bean cropland expansion and intensification
Watershed responses to Amazon soya bean cropland expansion and intensification
复制标题
亚马逊大豆农田扩张和集约化的分水岭反应
DOI：
--
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
L. Deegan
中科院分区：
文献类型：
--
作者：
C. Neill;M. Coe;S. Riskin;A. Krusche;H. Elsenbeer;M. Macedo;R. McHorney;P. Lefebvre;E. Davidson;Raphael Scheffler;A. Figueira;S. Porder;L. Deegan
亚马逊流域东南部大豆农业的扩张和集约化可以通过改变土地覆盖、水平衡和养分投入来改变流域水文和生物地球化学。最近在该地区开展的密集实地调查得出了关于流域水文学和生物地球化学对马托格罗索州森林砍伐的反应的一些新见解。由于蒸散量减少，大豆流域的总水输出量比森林增加了三到四倍。然而，广阔的高原上深厚且高渗透性的土壤为大豆小流域提供了缓冲，以抵御暴风雨的增加。森林或大豆流域之间的硝酸盐和磷酸盐浓度没有差异，因为铁和铝氧化物对磷肥的固定以及深层土壤中硝酸盐的阴离子交换限制了养分移动。尽管生物地球化学变化具有抵抗力，但由于蓄水和邻近河岸森林的减少，大豆流域的溪流温度较高。在较大的河流中，森林砍伐后水流、流速和沉积物通量的增加可以重塑河流形态，这表明小流域森林砍伐的累积影响将在更大范围内发生。
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.