Affiliation:
1. Imperial College London
2. Tsinghua University
3. University of Reading
4. Seoul National University
Abstract
Abstract
Vegetation cover regulates the exchanges of energy, water and carbon between land and atmosphere. Remotely-sensed fractional absorbed photosynthetically active radiation (fAPAR), a land-surface greenness measure, depends on carbon allocation to foliage while also controlling photon flux for photosynthesis. Greenness is thus both a driver and an outcome of gross primary production (GPP). An equation with just two (globally) fitted parameters describes seasonal maximum fAPAR (fAPARmax) as the smaller of a water-limited value transpiring a constant fraction of annual precipitation, and an energy-limited value maximizing annual plant growth. This minimalist description reproduces global greenness patterns, and the consistent temporal trends among remote-sensing products, as accurately as the best-performing dynamic global vegetation models. Widely observed greening is attributed to the influence of rising carbon dioxide on the light- and water-use efficiencies of GPP, augmented by wetting in some dry regions and warming in high latitudes. Limited regions show browning, attributed to drying.
Publisher
Research Square Platform LLC