Satellite observations of the contrasting response of trees and grasses to variations in water availability

Interannual variations in ecosystem primary productivity are dominated by water availability. Until recently, characterizing the photosynthetic response of different ecosystems to anomalies in soil moisture was hampered by observational limitations. Here we use a number of satellite-based proxies for productivity, including spectral indices, sun-induced chlorophyll fluorescence (SIF) and data-driven estimates of gross primary production (GPP), to re-evaluate the relationship between terrestrial photosynthesis and water. In contrast to non-woody vegetation, we find a resilience of forested ecosystems to reduced soil moisture. SIF and data-driven GPP indicate an increase in photosynthesis as a result of the accompanying higher amounts of light and temperature. Conversely, remote sensing indicators of greenness reach their detection limit and largely remain stable. Our study thus highlights the differential responses of ecosystems along a tree cover gradient and illustrates the importance of differentiating indicators of photoynthesis such as SIF from those of greenness for the monitoring and understanding of ecosystems.

WALTHER Sophia;  DUVEILLER BOGDAN Grégory Henry E;  JUNG M.;  GUANTER Luis;  CESCATTI Alessandro;  CAMPS-VALLS Gustavo; 

2019-02-19

AMER GEOPHYSICAL UNION

JRC113521

0094-8276 (online),   

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL080535,    https://publications.jrc.ec.europa.eu/repository/handle/JRC113521,   

10.1029/2018GL080535 (online),