Developing an Understanding of Vegetation Change and Fluvial Carbon Fluxes in Semi-Arid Environments at the Sevilleta National Wildlife Refuge, New Mexico: Rainfall Runoff Events

Dryland environments are estimated to cover around 40% of the global land surface, and are home to approximately 2.4 billion people. Many of these areas have recently experienced extensive land degradation. This study focuses on semi-arid areas in the US Southwest, where degradation over the past 150 years has been characterized by the invasion of woody vegetation into areas previously dominated by grasslands. This vegetation change has been associated with increases in soil erosion and water quality problems, including the loss of key nutrients such as carbon from the soil to adjacent fluvial systems. Such loss of resources may impact heavily upon the amount of carbon that is lost as the land becomes more heavily degraded.Therefore, understanding these vegetation transitions is significant both for sustainable land use and global biogeochemical cycling. This study uses an ecohydrological approach to develop an understanding of the relationship between structure and function across these transitions. This is done via the monitoring of rainfall-runoff events across instrumented runoff plots with different vegetation characteristics to investigate fluvial sediment fluxes during intense summer monsoon season rainfall events.据估算，干旱区环境（dryland environments）约占全球陆地总面积的40%，承载了约24亿人口。近年来，其中诸多区域出现了大范围的土地退化现象。本研究聚焦美国西南部的半干旱区，该区域过去150年间的土地退化特征表现为木本植被入侵此前以草原为主导的区域。此类植被变化与土壤侵蚀加剧及水质问题密切相关，具体包括土壤中的碳等关键养分流失至相邻的河流系统（fluvial systems）。这类资源流失可能在土地进一步退化时大幅增加碳的流失量。因此，明晰此类植被转变过程，对可持续土地利用与全球生物地球化学循环均具有重要价值。本研究采用生态水文学方法（ecohydrological approach），解析此类植被转变过程中生态系统结构与功能的关联。具体通过对不同植被特征的布设监测设备的径流小区（runoff plots）开展降雨径流事件（rainfall-runoff events）监测，探究夏季季风期强降雨过程中的河流泥沙通量（fluvial sediment fluxes）。