Premium
Greening drylands despite warming consistent with carbon dioxide fertilization effect
Author(s) -
Gonsamo Alemu,
Ciais Philippe,
Miralles Diego G.,
Sitch Stephen,
Dorigo Wouter,
Lombardozzi Danica,
Friedlingstein Pierre,
Nabel Julia E. M. S.,
Goll Daniel S.,
O'Sullivan Michael,
Arneth Almut,
Anthoni Peter,
Jain Atul K.,
Wiltshire Andy,
Peylin Philippe,
Cescatti Alessandro
Publication year - 2021
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.15658
Subject(s) - leaf area index , photosynthesis , water use efficiency , environmental science , agronomy , greening , ecosystem , carbon dioxide , botany , biology , ecology
The rising atmospheric CO 2 concentration leads to a CO 2 fertilization effect on plants—that is, increased photosynthetic uptake of CO 2 by leaves and enhanced water‐use efficiency (WUE). Yet, the resulting net impact of CO 2 fertilization on plant growth and soil moisture (SM) savings at large scale is poorly understood. Drylands provide a natural experimental setting to detect the CO 2 fertilization effect on plant growth since foliage amount, plant water‐use and photosynthesis are all tightly coupled in water‐limited ecosystems. A long‐term change in the response of leaf area index (LAI, a measure of foliage amount) to changes in SM is likely to stem from changing water demand of primary productivity in water‐limited ecosystems and is a proxy for changes in WUE. Using 34‐year satellite observations of LAI and SM over tropical and subtropical drylands, we identify that a 1% increment in SM leads to 0.15% (±0.008, 95% confidence interval) and 0.51% (±0.01, 95% confidence interval) increments in LAI during 1982‒1998 and 1999‒2015, respectively. The increasing response of LAI to SM has contributed 7.2% (±3.0%, 95% confidence interval) to total dryland greening during 1999‒2015 compared to 1982‒1998. The increasing response of LAI to SM is consistent with the CO 2 fertilization effect on WUE in water‐limited ecosystems, indicating that a given amount of SM has sustained greater amounts of photosynthetic foliage over time. The LAI responses to changes in SM from seven dynamic global vegetation models are not always consistent with observations, highlighting the need for improved process knowledge of terrestrial ecosystem responses to rising atmospheric CO 2 concentration.