LTREB: Evaluation of Landscape Patterns in Ecosystem Processes in Detrital-based Tropical Streams

这个LTREB项目的主要目标是了解哥斯达黎加低地热带溪流中地表水-地下水相互作用与生态系统过程之间的联系。重点是营养丰富的地下水如何影响溪流中微生物介导的分解过程，其中分解的有机物是更高营养水平的主要食物来源。项目负责人将研究由于富溶质地下水输入的变化而导致的河流溶质化学的景观模式，如何影响栖息在河流中的昆虫的生长模式和二次生产。首先，对昆虫次生生产的景观尺度变化受地暖地下水比例变化影响的假设进行验证。其次，为了分离出磷的影响，将继续进行全溪流P富集研究，以评估磷对昆虫生长速率、昆虫次生产量、叶片分解速率和与叶片分解相关的微生物活性的影响。随着磷可用性的增加，这些过程是否会受到氮的限制也将被确定。这项提案研究将首次确定湿润新热带地区碎屑流中营养物质富集的长期影响。此外，本研究将继续建立中美洲原始低地雨林中唯一的河流溶质化学长期数据集。河流溶质化学和面向生态系统过程的数据对于理解和管理热带森林以及预测区域和潜在的全球环境变化对这些受威胁的生态系统的影响具有重要意义。这个长期项目已经并将继续为其他生态系统研究提供重要信息，同时也为本科生和研究生的研究提供了大量机会。

0075339PringleThe primary objective of this LTREB project is to understand the link between surface-subsurface water interactions and ecosystem processes in tropical streams in lowland Costa Rica. The focus is on how nutrient-rich groundwater affects microbially-mediated decomposition processes in streams where decomposing organic matter is the primary food source for higher trophic levels. The PI's will examine how landscape patterns in stream solute chemistry, resulting from variation in solute-rich groundwater inputs, affect patterns in growth and secondary production of stream-dwelling insects. First, the hypothesis that landscape-scale variation in insect secondary production is affected by inter-stream variation in the proportion of geothermally modified ground water will be tested. Second, to isolate the effects of phosphorus, a whole stream P enrichment study will be continued to evaluate phosphorus effects on insect growth rates, insect secondary production, rates of leaf decomposition, and microbial activity associated with leaf decomposition. Whether or not these processes become N limited as P availability increases will also be determined. The proposal studies will be the first to determine the long-term effects of nutrient enrichment in a detrital-based stream in the wet neotropics. In addition, this research will continue to build the only long-term data set on stream solute chemistry in primary lowland rainforest in Central America. Stream solute chemistry and ecosystem process-oriented data are of fundamental importance to understanding and management of tropical forest and in predicting effects of regional and potentially global environmental change on these threatened ecosystems. This long-term program has provided, and will continue to provide, critical information for other ecosystem studies, along with numerous opportunities for undergraduate and graduate research.