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Evaluation of global maximum carboxylation rate of leaves using remotely sensed leaf chlorophyll content

Presentation Date
Wednesday, December 11, 2019 at 9:15am
Location
Moscone West 3001, L3
Authors

Author

Abstract

The maximum carboxylation rate (Vcmax) represents the intrinsic capability of leaves to take up CO2 through photosynthesis. Limited understanding of observed variability in Vcmax is a major source of uncertainty in today’s earth system models simulating global photosynthesis and the global carbon cycle. In recent years, scientists have proposed several ecological theories to derive seasonal- and spatially varying Vcmax, in an attempt to constrain the uncertainty of models. The resulting global Vcmax datasets can generally be categorized into 3 types: nutrient-driven, climate-driven and climate-nutrient-driven. The quality of these Vcmax products has yet to be evaluated. In this study, we aim to evaluate seven different global gridded Vcmax datasets using newly released satellite-derived global leaf chlorophyll content (Chl), based on the hypothesis that the variability of Chl is tightly coupled with Vcmax. Our results show that a climate-driven Vcmax product based on optimality theory has the strongest correlation with Chl for croplands and grasslands, while for forests, the climate-nutrient-driven Vcmax performed slightly better than those driven by climate only. Our study demonstrates a novel approach for testing ecological theories of photosynthetic potential using remote sensing observations, and implies a difference in the mechanisms underlying Vcmax seasonality and heterogeneity between different biomes.

Category
Biogeosciences
Funding Program Area(s)