Wu Genghong, Guan Kaiyu, Li Yan, Novick Kimberly A, Feng Xue, McDowell Nate G, Konings Alexandra G, Thompson Sally E, Kimball John S, De Kauwe Martin G, Ainsworth Elizabeth A, Jiang Chongya
College of Agricultural, Consumer and Environmental Sciences, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA.
National Center for Supercomputing Applications, University of Illinois at Urbana Champaign, Champaign, IL, 61820, USA.
New Phytol. 2021 Mar;229(5):2562-2575. doi: 10.1111/nph.17040. Epub 2020 Dec 3.
●Plants are characterized by the iso/anisohydry continuum depending on how they regulate leaf water potential (Ψ ). 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 Ψ . ●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.
●植物的特征在于根据它们调节叶片水势（Ψ）的方式形成的等水/非等水连续体。然而，等水/非等水如何随着时间的推移响应逐年变化的环境干燥程度而变化，以及这种响应在不同地区之间如何变化，仍然缺乏充分的特征描述。●我们研究了以干旱指数表示的干燥程度如何影响区域尺度上生态系统等水/非等水的年际变异性，该变异性是通过卫星微波植被光学深度（VOD）观测来估计的。这种生态系统层面的分析进一步通过已发表的物种水平Ψ的实地观测得到补充。●我们发现在不同生态系统中，等水性（σ）相对于干燥程度的年际变化在方向性和敏感性方面存在不同的表现。这些表现很大程度上可以通过生态系统本身的平均干燥程度来区分：在湿润生态系统中，σ在较干旱年份下降，对干燥程度的敏感性较高；在干旱生态系统中，σ在较干旱年份增加，对干燥程度的敏感性较低。这些结果得到了物种水平综合分析的支持。●我们的研究表明，植物如何逐年调整其水分利用——正如它们在等水性上的年际变异性所揭示的那样——取决于植物生存环境的干燥程度。这一发现推进了我们对区域尺度上植物对干旱响应的理解。
