Regional vegetation die-off in response to global-change-type drought
Regional vegetation die-off in response to global-change-type drought
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DOI：
10.1073/pnas.0505734102
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发表时间：
2005-10-18
影响因子：
11.1
通讯作者：
Meyer, CW
中科院分区：
文献类型：
--
作者：
Breshears, DD;Cobb, NS;Meyer, CW
随着气候变化的发展，未来的干旱预计将在气温升高的条件下发生，在此称为全球变化型干旱，但对干旱引起的植被死亡的触发因素和潜在程度的定量评估仍然是评估气候变化影响的关键不确定因素。特别值得关注的是区域范围内的死亡率的上层树木，迅速改变生态系统类型，相关的生态系统特性，以及几十年的地表条件。在这里，我们量化区域尺度的植被死亡在2002-2003年横跨北美西南部的林地在干旱和相关的树皮甲虫侵扰。在该地区的一个深入研究的地点，我们量化了15个月的土壤含水量耗尽后，>90%的优势，上层树种（Pinus edulis，一种松树）死亡。死亡反映在遥感植被绿色指数（归一化植被指数）的变化中，不仅在深入研究的地点，而且在整个区域，延伸超过12，000公里（2）或更多;航空和实地调查证实了死亡的一般程度。值得注意的是，最近的干旱比1950年代的前一次次大陆干旱要温暖。有限的，现有的观察表明，死亡从最近的干旱比以前的干旱更广泛，延伸到潮湿的网站内的树种分布。我们的研究结果量化了一个触发器，导致快速，干旱引起的死在次大陆尺度的上层木本植物，并强调这种死亡的潜力是更严重和广泛的未来全球变化型干旱在温暖的条件下。
Future drought is projected to occur under warmer temperature conditions as climate change progresses, referred to here as global-change-type drought, yet quantitative assessments of the triggers and potential extent of drought-induced vegetation die-off remain pivotal uncertainties in assessing climate-change impacts. Of particular concern is regional-scale mortality of overstory trees, which rapidly alters ecosystem type, associated ecosystem properties, and land surface conditions for decades. Here, we quantify regional-scale vegetation die-off across southwestern North American woodlands in 2002-2003 in response to drought and associated bark beetle infestations. At an intensively studied site within the region, we quantified that after 15 months of depleted soil water content, >90% of the dominant, overstory tree species (Pinus edulis, a pinon) died. The die-off was reflected in changes in a remotely sensed index of vegetation greenness (Normalized Difference Vegetation index), not only at the intensively studied site but also across the region, extending over 12,000 km(2) or more; aerial and field surveys confirmed the general extent of the die-off. Notably, the recent drought was warmer than the previous subcontinental drought of the 1950s. The limited, available observations suggest that die-off from the recent drought was more extensive than that from the previous drought, extending into wetter sites within the tree species' distribution. Our results quantify a trigger leading to rapid, drought-induced die-off of overstory woody plants at subcontinental scale and highlight the potential for such die-off to be more severe and extensive for future global-change-type drought under warmer conditions.