Community Structure Before and During a Record Drought: The Impact of Climate Change on Biodiversity. Does It Matter?

美国西部部分地区正在经历世纪以来最严重的干旱之一，但人们对这种气候变化如何影响生物多样性（物种数量及其丰度）、灭绝、物种之间的相互作用以及这些相互作用的遗传基础知之甚少，所有这些都最终决定了这些生态系统的健康。 研究人员对松树进行了21年的观察和实验，跨越了有史以来最潮湿和最干燥的时期，使他们能够解决这些关键问题。在长期的潮湿时期，PI量化了环境压力和松树的遗传属性如何影响约400种真菌和昆虫。现在，经过7年的干旱，他们将重新访问早期的研究地点：（1）确定干旱引起的生物多样性变化如何影响松树在大多数树木死于干旱的地区重新建立的能力;（2）确定干旱胁迫是否导致植食性昆虫数量增加攻击干旱敏感的树木，这反过来又改变了社区的其他部分;（3）确定干旱是否减少了有益的土壤真菌，这些真菌是树木生存所必需的，并使相关的社区从干旱中恢复过来;（4）测试树木年轮是否可以用来预测未来气候条件将如何影响生物多样性。因为松属植物是美国第三大分布最广的植被类型，这项工作的结果很可能适用于美国的其他地区。此外，鉴于干旱的频率和严重程度预计将在世界许多地区增加，而构成我们生物多样性研究重点的真菌和昆虫是全球生态系统的重要组成部分，这项研究可能有助于预测其他系统的变化。 该研究计划包括培训研究生和本科生，包括美洲原住民和西班牙裔，并向土地管理人员和对干旱对生态系统的影响感兴趣的当地社区提供宣传。

Portions of the western United States are experiencing one of the worst droughts in a century, but little is known about how such climate change affects biodiversity (the number of species and their abundance), extinction, interactions among species, and the genetic basis of these interactions, all of which ultimately determine the health of these ecosystems. The investigators' 21-years of observations and experiments with pinyon pine span the wettest and driest periods of recorded history, allowing them to address these critical issues. During a long-term wet period, the PIs quantified how environmental stress and the genetic attributes of pinyon pine trees affected ~400 species of fungi and insects. Now, after 7 years of drought, they will revisit earlier study sites to: (1) determine how drought-induced changes in biodiversity affect the ability of pinyon pine to re-establish in areas where most trees have succumbed to drought; (2) determine if drought stress has resulted in increased numbers of herbivorous insects that attack drought-sensitive trees, which in turn alters the rest of the community; (3) determine if drought has reduced beneficial soil fungi that are necessary for tree survival and that allow the associated community to recover from drought; and (4) test whether tree rings can be used to predict how future climatic conditions will affect biodiversity. Because pinyon is a widespread conifer of the third most widespread vegetation type in the U.S., results from this work is likely to to apply to other areas of the U.S. Also, given that the frequency and severity of drought is predicted to increase in many areas of the world, and that the fungi and insects that form the focus of our biodiversity studies are important components of ecosystems world-wide, this research may help to predict changes in other systems. The research program includes training of graduate and undergraduate students, including Native Americans and Hispanics, and provides outreach to land managers and the local community interested in the impacts of drought on ecosystems.