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-地下水相互作用和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，在溪流中，分解的有机物是较高营养水平的主要食物来源。PI将研究由于富含溶质的地下水输入的变化而导致的溪流溶质化学景观模式如何影响溪流昆虫的生长和次生生产模式。首先，将检验这样一种假设，即昆虫次生生产力的景观尺度变化受到地热改造地下水比例的河流间变化的影响。第二，为了分离磷的影响，将继续进行一项全溪流磷富集研究，以评估磷对昆虫生长速度、昆虫次生生产力、叶片分解速度以及与叶片分解相关的微生物活动的影响。还将确定这些过程是否随着P有效性的增加而变得N受限。这项拟议的研究将首次确定在湿润的新热带地区以碎屑为基础的溪流中营养丰富的长期影响。此外，这项研究还将继续建立中美洲原始低地雨林中唯一的溪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了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至关重要。这一长期计划已经并将继续为其他生态系统研究提供关键信息，以及为本科生和研究生研究提供大量机会。

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.