Doctoral Dissertation Research: Changing the Amazon Landscape: Dynamics of Land Use and Ecological Change in Small Watersheds

土地利用的变化极大地影响了溪流和相关流域的水质和生物生产力，特别是在巴西亚马逊流域，那里的森林砍伐和广泛的农业导致包括水源集水区在内的流域的地表水流量和养分损失增加。人们认为，经济和社会人口因素在组织这些变化方面发挥了关键作用；特别是，受环境因素、政府政策以及土地利用和水质知识驱动的家庭决策是推动小流域土地和水利用选择的重要组成部分。这些用途对排水小流域的溪流的水质，特别是对溪流生态系统的生物生产力很重要的营养物的数量和类型产生了具体的影响。因此，本研究评估了家庭需求和活动、土地和水的使用以及对水质的认识对巴西阿尔塔米拉附近一个农业居民点小流域溪流水质的影响。评估了两种流域土地覆盖梯度的重要性：流域的森林数量和流域的非森林数量，如牧场或可可种植园，这是阿尔塔米拉附近两种最主要的土地利用。采用标准采样技术，对流域流出点的水质和溪流中溶解的营养物浓度（碳、氮、磷）进行检测，总结了流域土地利用对溪流水质的影响。此外，对小农的采访提供了关于家庭结构的信息以及对土地利用与水质之间关系的了解。目前正在利用遥感分析和地理信息系统来产生关于流域土地利用变化的较大空间格局的信息。研究人员假设，外部市场因素，如农产品价格和农业用水需求的增加，是驱动土地利用和随后水质和溪流溶解营养物质变化的主要因素。这项研究的结果将为陆地和水生生态系统的家庭土地利用和环境变化提供有价值的见解。此外，由于小河在亚马逊流域广泛分布，并为许多亚马逊居民提供重要的资源，包括食物和饮用水，这项研究的结果将提供见解，以尽量减少对水质的有害影响，特别是通过了解家庭农业用地和用水如何影响溪流的潜在水质和健康。在关注巴西亚马逊地区土地利用变化的同时，这项研究也解决了世界范围内的土地利用问题，因为当地亚马逊流域的变化最终会扩大规模，影响全球生态，如全球营养循环，以及农业和贸易等经济。作为博士论文研究改进奖，该奖项还将为博士生的独立研究提供支持。

Land use changes have dramatically affected the water quality and biological productivity of streams and associated watersheds, particularly within the Brazilian Amazon Basin, where deforestation and extensive agriculture have led to increased surface water flow and nutrient losses from watersheds, including headwater catchments. It is thought that economic and socio-demographic factors have played critical roles in structuring these changes; in particular, household decisionmaking, driven by environmental factors, government policies, and knowledge of land use and water quality are important components driving land and water use choices in small watersheds. These uses have specific outcomes for the water quality found in streams draining small watersheds, particularly the quantity and type of nutrients that are important for the biological productivity of stream ecosystems. As a result, this study evaluates the role of household needs and activities, land and water use, and perception of water quality in affecting the water quality of small watershed streams in an agricultural settlement near Altamira, Brazil. The importance of two kinds of watershed land cover gradients are assessed: amount of forest in a watershed and amount of non-forest in a watershed, as pasture or cacao plantations, which are the two most predominant land uses near Altamira. Examination of water quality and stream water dissolved nutrient concentrations (carbon, nitrogen, phosphorus) at watershed stream outflow points, using standard sampling techniques, provides a summary of the impact of watershed land use on stream water quality. In addition, interviews with small farmers provide information on household structure and knowledge of the relationship between land use and water quality. Remote sensing analyses and a geographic information system are being used to generate information on larger spatial patterns of watershed land use changes. The investigators hypothesize that external market factors, such as prices for agricultural goods, and increasing water needs from agriculture are the predominant factors driving land use and subsequent changes in water quality and stream water dissolved nutrients.The results of this study will provide valuable insights into household land use and environmental change in terrestrial and aquatic ecosystems. In addition, as small streams are widespread in the Amazon Basin and provide important resources for many Amazonian inhabitants, including food and drinking water, the results of this research will provide insights to minimize detrimental impacts on water quality, particularly through understanding how household agricultural land and water use affects the underlying water quality and health of streams. While focused on land use changes in the Brazilian Amazon, this research also addresses land use issues worldwide, as local Amazonian watershed changes ultimately scale-up to affect worldwide ecology, such as global nutrient cycles, and economy, such as agriculture and trade. As a Doctoral Dissertation Research Improvement award, this award also will provide support to foster independent research by a doctoral student.