Dissertation Research: The Effect of Water on Carbon Cycling and Soil Carbon Storage in High Precipitation Ecosystems

9700929马特森本研究计划旨在确定水对高降水量非湿地生态系统中碳循环生物过程的影响。虽然水对碳动力学的影响是很好的研究，在陆地系统中的干中质，它仍然很难定义在中湿生态系统，虽然土壤碳储量的模式表明，这是很重要的。实验方法使用自然发生的降雨梯度在夏威夷，所有其他国家的因素，可以影响碳动态之间的网站举行显着不变，而降雨量仅从2500毫米到6000毫米系统的变化。本研究的重点是水分解和净初级生产力的影响，土壤碳储量的主要机制。主要的假设是，净初级生产力和分解的负面影响，在这些陆地系统的水，分解率的影响是强相对于净初级生产力的影响，水直接抑制氧气和养分的可用性。通过直接测量净初级生产力和分解率的变化，通过使用土壤和植物组织的13 C质谱作为碳通量的综合措施，以及通过分析土壤大气和养分的可用性，将在整个梯度上评估增加水的影响。 了解土壤碳储量的机械控制对于预测全球土壤碳库对气候变化的瞬态响应非常重要;虽然土壤碳储量在降水轴上线性增加，但这掩盖了控制储量的过程中的真实的变化。这项研究将提供一个强大的经验测试的水对生产和分解在高降水量的生态系统的影响，并将这些碳循环过程中的变化，土壤碳储量的模式。 NSF表格1358（1/94）

9700929 Matson This research proposal is designed to determine the effect of water on biological processes involved in carbon cycling in high precipitation, non-wetland ecosystems. While the influence of water on carbon dynamics is well studied in dry to mesic terrestrial systems, it remains poorly defined in mesic to wet ecosystems although patterns of soil carbon storage suggest that it is important. The experimental approach uses a naturally occurring rainfall gradient in Hawaii; all other state factors that can affect carbon dynamics are held remarkably constant among sites, while rainfall alone changes systematically from 2500 mm to 6000 mm. This study focuses on the effect of water on decomposition and net primary productivity as the primary mechanisms of soil carbon storage. The main hypotheses are that net primary productivity and decomposition are negatively affected by water in these terrestrial systems; that the effect on decomposition rates is stronger relative to the effect on net primary productivity; and that water directly suppresses both oxygen and nutrient availability. The effect of increasing water will be evaluated across the gradient by directly measuring changes in net primary productivity and decomposition rates, by using 13C mass spectroscopy of soils and plant tissue as integrated measures of carbon fluxes, and by analysis of the soil atmosphere and nutrient availability. Understanding the mechanistic controls over soil carbon storage is important for predicting the transient response of the global soil carbon pool to climate change; though soil carbon storage increases linearly across the axis of precipitation, this masks real changes in the processes that control storage. This research will provide a robust empirical test of the effect of water on production and decomposition in high precipitation ecosystems, and will link changes in these carbon cycling processes to patterns of soil carbon storage. NSF Form 1358 (1/94)