Controls on carbon exchange in Boreal ecosystems

对碳交换的生物物理控制的机械理解需要研究年内和年际气候趋势如何影响地表-大气交换。拟议的研究将量化北方生态系统和大气之间的二氧化碳净生态系统交换的动态。塔为基础的CO2通量将连续测量使用微气象方法在一个黑云杉林和泥炭地生态系统几年在东部詹姆斯湾地区的北方森林。这两个油田所在地相距几公里，因此受到相同的环境条件的影响。光利用效率将从基于塔的吸收光合有效辐射和总生态系统生产力的测量中得出。将利用一套微气象学和生物物理学变量来调查环境控制对每个地点土地利用效率变化的影响。遥感植被指数在各种空间尺度上都与土地利用效率相关。因此，将结合使用各种遥感技术来提高通量。将使用安装在塔上的辐射计对植被指数进行高分辨率连续测量。植被指数和基于塔的通量之间的关系将从这些实地测量。地面算法将应用于可比的卫星指数，从而得出生态系统规模的碳交换估计数。该研究旨在提供更多的知识的关键过程和环境强迫，驱动大气生态系统C交换的时间尺度，从瞬时，季节，年度通过年际。关于生态系统生理反应的详细信息可进一步用于修改和验证生态系统模型，成为研究气候变化反应的工具。

A mechanistic understanding of the biophysical controls on carbon exchange necessitates a study of how intra- and inter-annual climate trends affect surface-atmosphere exchanges. The proposed research will quantify the dynamics of net ecosystem exchange of carbon dioxide between a boreal ecosystem and the atmosphere. Tower-based fluxes of CO2 will be continuously measured using micrometeorological methods over a black spruce forest and peatland ecosystem for several years in the eastern James Bay region of the boreal forest. The two field locations are located within several kms of each other and are therefore subjected to the same environmental conditions. Light use efficiency (LUE) will be derived from tower-based measurements of absorbed photosynthetically active radiation and gross ecosystem productivity. The influence of environmental controls on the variation in LUE at each site will be investigated using the set of micrometeorological and biophysical variables. Remotely sensed vegetation indices have been shown to be correlated with LUE at a variety of spatial scales. Upscaling of fluxes will therefore be accomplished using a combination of remote sensing techniques. Tower-mounted radiometers will be used to provide high resolution continuous measurements of vegetation indices. Relationships between vegetation indices and tower-based fluxes will be developed from these field measurements. Ground based algorithms will be applied to comparable satellite-based indices resulting in ecosystem scale estimates of carbon exchange. The research is designed to provide increased knowledge of the critical processes and environmental forcings which drive the atmosphere ecosystem C exchange on time scales ranging from instantaneous, seasonal, annual through inter-annual. Detailed information on ecosystem physiological responses can further be used to modify and validate ecosystem models - becoming tools for studying responses to changing climate.