RAPID: Using a natural extreme freeze in New Mexico to test predictions regarding the physiological basis of freezing tolerance in natural populations.

植物和其他生物一样，生理极限决定了生存和生长的环境条件。对大多数物种来说，尤其是常绿植物，当地罕见的极端气候可能会超过生理极限，导致植物死亡或严重限制其功能。极端事件的影响可以持续几十年，影响生态系统的生态（生长、繁殖、物种组成等）和社会学（审美品质、土地价值、淡水等）功能。2011年2月，新墨西哥州中部和南部遭遇极端严寒，这一项目将检验过去对木榴灌木（Larrea tridentata）生理极限测量的预测。木榴灌木是一种分布广泛的常绿沙漠灌木，在西南地区占据了数百万英亩的土地。该项目将测量新墨西哥州中部和南部木砂树的冻害和恢复，测试最近研究中确定的特征预测自然冻结造成的损害的能力，并使用卫星图像量化整个季节植物损害的广泛模式（以植物冠层绿度测量），并将它们与我们目前对木砂树生理极限的理解联系起来。我们期望已知的生理极限可以解释冰冻后的直接损害，但通过根系再生可以降低土壤和卫星测量的死亡率。该项目将提高我们对植物对极端事件的反应以及这些反应的大规模影响的理解和预测能力。我们需要了解对极端事件的反应，因为持续的气候变化可能会改变它们，从而改变它们对植被的影响。本项目将培养1名博士后和2名研究生，研究成果将向中小学生和社会公众发布。

In plants, like other organisms, physiological limits define environmental conditions allowing survival and growth. For most species, especially evergreens, the rare extremes of local climate may exceed physiological limits, killing plants or severely limiting their function. The effects of extreme events can persist for decades, affecting the ecological (growth, reproduction, species composition, etc.) and sociological (aesthetic qualities, land value, freshwater, etc.) functions of that ecosystem. This project will test predictions from past measurements of the physiological limits of creosotebush (Larrea tridentata), a widespread evergreen desert shrub dominating millions of acres in the southwest, following an extreme freeze in central and southern New Mexico in February 2011. The project will measure freezing damage and recovery of creosotebush in central and southern NM, test the ability of characteristics identified in recent research to predict the damage caused by the natural freeze and, use satellite images to quantify the broad patterns of plant damage (measured as plant canopy greenness) throughout the season and link them to our present understanding of the physiological limits of creosotebush. We expect known physiological limits will explain immediate post-freeze damage but mortality in plot and satellite measurements will be reduced by regrowth from roots. This project will improve our understanding and ability to predict plant responses to extreme events and the large-scale effects of these responses. We need to understand the response to extreme events because ongoing climate change may alter them and thus their effect on vegetation. This project will train a postdoctoral scientist and two graduate students and results will be disseminated to primary and undergraduate students and the general public.