Surface temperatures reveal the patterns of vegetation water stress and their environmental drivers across the tropical Americas
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- Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA-Saclay), Gif-sur-Yvette (France). CNRS, UVSQ, Le Laboratoire des Sciences du Climat et de l’Environnement; Univ. of California, Berkeley, CA (United States)
- Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA-Saclay), Gif-sur-Yvette (France). CNRS, UVSQ, Le Laboratoire des Sciences du Climat et de l’Environnement; Univ. of Montana, Missoula, MT (United States)
- Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA-Saclay), Gif-sur-Yvette (France). CNRS, UVSQ, Le Laboratoire des Sciences du Climat et de l’Environnement; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Columbia Univ., New York, NY (United States); Columbia Univ., New York, NY (United States). Earth Inst.
- Univ. Paris-Saclay (France). Inst. National de la Recherche Agronomique, AgroParisTech
- Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA-Saclay), Gif-sur-Yvette (France). CNRS, UVSQ, Le Laboratoire des Sciences du Climat et de l’Environnement
Vegetation is a key component in the global carbon cycle as it stores ~450 GtC as biomass, and removes about a third of anthropogenic CO2 emissions. However, in some regions, the rate of plant carbon uptake is beginning to slow, largely because of water stress. Here, we develop a new observation-based methodology to diagnose vegetation water stress and link it to environmental drivers. We used the ratio of remotely sensed land surface to near surface atmospheric temperatures (LST/Tair) to represent vegetation water stress, and built regression tree models (random forests) to assess the relationship between LST/Tair and the main environmental drivers of surface energy fluxes in the tropical Americas. We further determined ecosystem traits associated with water stress and surface energy partitioning, pinpointed critical thresholds for water stress, and quantified changes in ecosystem carbon uptake associated with crossing these critical thresholds. Additionally, we found that the top drivers of LST/Tair, explaining over a quarter of its local variability in the study region, are (1) radiation, in 58% of the study region; (2) water supply from precipitation, in 30% of the study region; and (3) atmospheric water demand from vapor pressure deficits (VPD), in 22% of the study region. Regions in which LST/Tair variation is driven by radiation are located in regions of high aboveground biomass or at high elevations, while regions in which LST/Tair is driven by water supply from precipitation or atmospheric demand tend to have low species richness. Carbon uptake by photosynthesis can be reduced by up to 80% in water-limited regions when critical thresholds for precipitation and air dryness are exceeded simultaneously, that is, as compound events. Our results demonstrate that vegetation structure and diversity can be important for regulating surface energy and carbon fluxes over tropical regions.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- French National Research Agency (ANR); USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1862125
- Journal Information:
- Global Change Biology, Journal Name: Global Change Biology Journal Issue: 9 Vol. 28; ISSN 1354-1013
- Publisher:
- WileyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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