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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Coping With Extreme Events: Growth and Water-Use Efficiency of Trees in Western Mexico During the Driest and Wettest Periods of the Past One Hundred Sixty Years
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Coping With Extreme Events: Growth and Water-Use Efficiency of Trees in Western Mexico During the Driest and Wettest Periods of the Past One Hundred Sixty Years

机译：应对极端事件：在过去一百六十年的最干燥和最潮湿的时期，墨西哥西部的树木的生长和水利用效率

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Understanding how trees respond to extreme events is important to predict how climate change will impact forests in the future. In this study, we report changes in radial growth and tree-ring carbon (δ~(13)C) and oxygen (δ~(18)O) stable isotope ratios of Pseudotsuga menziesii (Douglas-fir) in western Mexico. Tree growth was compared with δ~(13)C and δ~(18)O ratios recorded during dry and wet periods caused by El Ni?o-Southern Oscillation since 1850. The three driest and three wettest events during the studied period caused tree growth decline of up to 50% followed by 6-10 years of slow recovery until baseline growth was regained. Wet events resulted in up to 17% growth increase, a positive effect that persisted for no more than 3-5 years. Stable isotope ratios recorded physiological adjustments that in some cases correlated significantly with tree growth. Excursions in tree-ring Δ~(13)C and δ~(18)O isotope ratios suggest that trees cope with dry and wet periods with proportional but divergent adjustments in photosynthesis versus stomatal conductance. Notably, the intrinsic water-use efficiency-that is, the ratio between carbon assimilation and water loss through transpiration-was positively correlated with tree basal growth only during dry periods. We found no significant correlations between growth and intrinsic water-use efficiency during wet periods. Contrary to expectations, rising CO_2 levels over the past ~160 years did not affect tree growth response to precipitation variability.
机译：了解树木如何应对极端事件对于预测气候变化将如何影响森林将来是如何影响。在这项研究中，我们报告了墨西哥州西氏菌（Dirsuda-FiRS）稳定同位素比（Dirdotsuga Menziesii（Douglas-FiR）的辐射生长和树木碳（δ〜（18）o）的变化。将树生长与Δ〜（13）C和δ〜（18）比率进行比较，在1850年以来的干燥和潮湿期间记录的干燥和潮湿时段。在研究期间三个干燥和三个最潮湿的事件导致树增长跌幅高达50％，后跟3-10年的缓慢恢复，直到恢复基线增长。潮湿事件导致增长率高达17％，持续不超过3 - 5年的积极效果。稳定的同位素比记录生理调整，在某些情况下，在某些情况下具有显着相关的树木生长。树木环δ〜（13）C和δ〜（18）o同位素率表明树木应对干燥和潮湿的时期，在光合作用与气孔导度相反的比例但发散的调整。值得注意的是，内在的水使用效率 - 即通过蒸腾碳同化和水损失的比率 - 仅在干燥时期与树基底生长正相关。我们发现在潮湿时期的生长和内在水使用效率之间没有显着相关性。与期望相反，过去〜160岁的CO_2水平上升并未影响降水变异性的树增长响应。

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