LTREB: Evaluation of Geothermally-modified Runoff and Nutrient Cycling in a Lowland Tropical Stream

以前的研究主要集中在哥斯达黎加低地雨林中地热引入的溶质和溪流生态之间的联系。结果表明，富磷河流与贫磷河流“并排”存在。高磷的来源是经过地热改造的地下水，它在溪流溶质化学方面产生了很高的空间变异性。这些发现代表了流经中美洲大部分火山脊的溪流的模式。这项研究将以这些先前的发现为基础。目前的项目将评估河流溶质化学，并纳入哥斯达黎加两条主要河流流域与当地流域径流和地热输入有关的重要地貌特征。待验证的假设表明，地表水和地下水溶质化学的时空格局与火山景观的三个主要地貌特征有关。在其中一个研究流域中，以过程为导向的研究将使河流溶质化学和运输与生态系统和景观水平的过程联系起来。实验和溪流监测将检验这样一种假设，即地表水中藻类生长和凋落叶分解的营养限制的时空格局是由地热引入的磷的存在与否以及河道的物理/水文特征所控制的。该项目的结果将包括中美洲主要低地热带雨林中唯一的河流溶质化学长期数据集。溪流溶质化学和面向过程的数据对于寻求理解和管理热带森林以及预测区域环境变化对这些受威胁的生态系统的影响的科学家至关重要。

9528434 Pringle Previous research focused on the linkage between geothermally-introduced solutes and stream ecology in lowland rain forests of Costa Rica. Results indicated that phosphorus-rich streams exist 'side-by-side' with phosphorus poor streams. The source of the high phosphorus is geothermally-modified groundwater that creates a high spatial variability in stream solute chemistry. These findings represent patterns among streams draining much of the volcanic spine of Central America. This research will build on these previous findings. The current project will evaluate stream solute chemistry and incorporate important geomorphic features associated with local watershed runoff and geothermal inputs along two major stream drainages in Costa Rica. The hypothesis to be tested states that spatial and temporal patterns in solute chemistry of surface- and ground-water are related to three major geomorphic features of the volcanic landscape. Process oriented studies in one of the study drainages will allow the linkage of stream solute chemistry and transport to ecosystem- and landscape-level processes. Experiments and stream monitoring will test the hypothesis that spatial and temporal patterns in nutrient limitation of algal growth and leaf litter decomposition in surface waters are controlled by the presence or absence of geothermally-introduced phosphorus, along with physical/hydrological characteristics of the stream channel. Results from this project will comprise the only long-term data set on stream solute chemistry for primarily lowland tropical rainforest in Central America. Stream solute chemistry and process-oriented data are of fundamental importance to scientists seeking to understand and manage tropical forests and to predict the effects of regional environmental change on these threatened ecosystems.