●Plants are characterized by the iso/anisohydry continuum depending on how they regulate leaf water potential (ΨL). However, how iso/anisohydry changes over time in response to year-to-year variations in environmental dryness and how such responses vary across different regions remains poorly characterized. ●We investigated how dryness, represented by aridity index, affects the interannual variability of ecosystem iso/anisohydry at the regional scale, estimated using satellite microwave vegetation optical depth (VOD) observations. This ecosystem-level analysis was further complemented with published field observations of species-level ΨL. ●We found different behaviors in the directionality and sensitivity of isohydricity (σ) with respect to the interannual variation of dryness in different ecosystems. These behaviors can largely be differentiated by the average dryness of the ecosystem itself: in mesic ecosystems, σ decreases in drier years with a higher sensitivity to dryness; in xeric ecosystems, σ increases in drier years with a lower sensitivity to dryness. These results were supported by the species-level synthesis. ●Our study suggests that how plants adjust their water use across years – as revealed by their interannual variability in isohydricity – depends on the dryness of plants’ living environment. This finding advances our understanding of plant responses to drought at regional scales.
Bibliographical noteFunding Information:
KG and GW acknowledge the support from NASA Carbon Monitoring System (NASA 80NSSC18K0170) managed by the NASA Terrestrial Ecology Program, and NSF CAREER award through the NSF Environmental Sustainability Program (NSF CBET 18‐47334 CAR). NGM was supported by the Department of Energy's Next Generation Ecosystem Experiment‐Tropics. All the data used in this manuscript were collected from literature and we appreciate those authors for publishing their data.
© 2020 The Authors New Phytologist © 2020 New Phytologist Trust
- interannual variability
- leaf water potential
- vegetation optical depth (VOD)