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Greening drylands despite warming consistent with carbon dioxide fertilization effect.
Alemu Gonsamo1, Philippe Ciais2, Diego G Miralles3
1School of Earth, Environment and Society, McMaster University, Hamilton, ON, Canada.
Global Change Biology
|April 28, 2021
Summary
Rising atmospheric CO2 enhances plant water-use efficiency (WUE) and growth in drylands. Satellite data show increased leaf area index (LAI) response to soil moisture, indicating greater foliage sustained by less water over time.
Area of Science:
- Ecology
- Environmental Science
- Remote Sensing
Background:
- Rising atmospheric CO2 concentrations stimulate plant growth via CO2 fertilization, increasing CO2 uptake and water-use efficiency (WUE).
- The large-scale impact of CO2 fertilization on plant growth and soil moisture (SM) savings remains unclear, especially in water-limited ecosystems.
- Drylands are ideal for studying CO2 fertilization effects due to the tight coupling of foliage amount, water use, and photosynthesis.
Purpose of the Study:
- To investigate the long-term impact of CO2 fertilization on plant growth and soil moisture dynamics in tropical and subtropical drylands.
- To analyze changes in the response of leaf area index (LAI) to soil moisture (SM) as a proxy for WUE.
- To compare satellite-observed trends with dynamic global vegetation model (DGVM) simulations.
Main Methods:
- Utilized 34-year satellite observations (1982-2015) of LAI and SM in tropical and subtropical drylands.
- Quantified the relationship between SM increments and LAI increments across two distinct time periods (1982-1998 and 1999-2015).
- Assessed the contribution of changing LAI-SM response to overall dryland greening.
Main Results:
- A 1% increase in SM corresponded to a 0.15% LAI increase (1982-1998) and a 0.51% LAI increase (1999-2015).
- The enhanced LAI response to SM contributed 7.2% to dryland greening between 1999-2015, compared to 1982-1998.
- Observed LAI-SM responses suggest improved WUE, with more foliage sustained by available soil moisture over time.
Conclusions:
- The increasing LAI response to SM supports the CO2 fertilization effect on WUE in drylands.
- Satellite data reveal significant shifts in vegetation dynamics attributable to CO2 and water interactions.
- Discrepancies between observed and modeled LAI responses highlight the need for improved vegetation models to capture ecosystem responses to rising CO2.
Keywords:
CO2 fertilization effectdryland greeningdynamic global vegetation modelleaf area indexsatellite soil moisturewater-use efficiencyMore Related Videos
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