Climate change increases carbon allocation to leaves in early leaf green‐up

Abstract

AbstractGlobal greening, characterized by an increase in leaf area index (LAI), implies an increase in foliar carbon (C). Whether this increase in foliar C under climate change is due to higher photosynthesis or to higher allocation of C to leaves remains unknown. Here, we explored the trends in foliar C accumulation and allocation during leaf green‐up from 2000 to 2017 using satellite‐derived LAI and solar‐induced chlorophyll fluorescence (SIF) across the Northern Hemisphere. The accumulation of foliar C accelerated in the early green‐up period due to both increased photosynthesis and higher foliar C allocation driven by climate change. In the late stage of green‐up, however, we detected decreasing trends in foliar C accumulation and foliar C allocation. Such stage‐dependent trends in the accumulation and allocation of foliar C are not represented in current terrestrial biosphere models. Our results highlight that a better representation of C allocation should be incorporated into models.