Inferring Amazon leaf demography from satellite observations of leaf area index

[摘要] Seasonal and year-to-year variations in leaf cover imprint significantspatial and temporal variability on biogeochemical cycles, and affectland-surface properties related to climate. We develop a demographic model ofleaf phenology based on the hypothesis that trees seek an optimal leaf areaindex (LAI) as a function of available light and soil water, and fit it tospaceborne observations of LAI over the Amazon basin, 2001–2005. We find themodel reproduces the spatial and temporal LAI distribution whilst alsopredicting geographic variation in leaf age from the basin centre(2.1 ± 0.2 years), through to the lowest values over the deciduouseastern and southern Amazon (6 ± 2 months). The model explains theobserved increase in LAI during the dry season as a net addition of leaves inresponse to increased solar radiation. We anticipate our work to be astarting point from which to develop better descriptions of leaf phenology toincorporate into more sophisticated earth system models.

[学科分类] 地球化学与岩石