期刊名称：ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences
印刷版ISSN：2194-9042
电子版ISSN：2194-9050
出版年度：2007
卷号：XXXVI-3/W52
页码：96-101
出版社：Copernicus Publications
摘要：Fluxes of carbon dioxide (CO 2 ), water, and energy measured using the eddy covariance method (EC) will vary spatially and temporally within the catchment area of the EC system, especially if parts of the forest are structurally heterogeneous. This is important because within site vegetation structural and topographic heterogeneity may tip the balance between an ecosystem being a net sink or source of CO 2 within a given year. Further, if wind directions are non-varying, the EC method may possibly either over- or under-estimate energy and mass fluxes if source locations are not representative of the entire ecosystem. The following study will use airborne lidar assessments of canopy structure, a simple flux footprint parameterisation, and EC estimates of net ecosystem productivity (NEP), ecosystem respiration (Re), and gross ecosystem productivity (GEP) to test the hypothesis that vegetation structural heterogeneity has some influence on CO 2 fluxes within a mature jack pine forest in Saskatchewan, Canada. The results found in this study indicate that vegetation structural variability (canopy height, depth, and foliage amount) within the site have significant influences on the variability in CO 2 flux estimates of uptake and respiration made using the EC method. However structural heterogeneity is not more important than meteorological driving mechanisms. The influences of structure may therefore become more influential in more heterogeneous ecosystems. Variability in vegetation fractional cover (a proxy indicator for foliage amount) and height, observed from airborne lidar, have the greatest influences on NEP and GEP, where increased fractional cover is directly related to increased CO 2 uptake on most days studied
