Consequences of Drought for Populations of Cryptantha flava

9527833卡斯珀根据预测全球气候长期变化的模型，半沙漠地区预计将变得更加干燥。这项研究的目的是预测这些地区的自然植物种群将如何应对干旱条件。大多数关于植物水分利用的生态学研究都集中在允许特定物种占据干燥栖息地的解剖或生理适应上。几乎没有努力确定人口和社区将如何应对可用水的时间变化。要做到这一点，我们需要了解干旱如何根据个体的大小、发育阶段或与其他植物的联系来影响个体。研究人员将通过在春季暴雨期间建立临时避难所，试验性地减少半荒漠草本植物多年生隐翅虫自然种群接收的降雨量。这项研究是基于在自然干旱年收集的数据，数据表明较大的植物比较小的植物受到干旱的影响更严重。将对不同大小和不同微生境、灌木下或露天的不同个体的生存、生长和开花进行比较，无论是在水量减少的地区还是在自然降雨量较大的地区。这些人口统计数据将通过测量用水量、叶片含氮量和光合作用来补充。这些类型的测量将有助于确定为什么个人会像他们那样对水供应的变化做出反应。水的实验减少将在空间上重复，并在两个不同的年份进行。将在干旱前一年、干旱年和干旱后一年对相同的个体进行人口统计和生理测量。这个实验的重复性很重要，因为在实验过程中很可能会发生降雨量的自然变化。这项研究还应有助于确定干旱年本身以外的挥之不去的影响。

9527833 Casper Under models that predict long-term changes in global climate, semi-desert regions are expected to become even drier. The purpose of this study is to predict how natural populations of plants in these regions will respond to drought conditions. Most ecological studies of water use in plants have focused on anatomical or physiological adaptations that allow particular species to occupy dry habitats. There has been little effort to determine how populations and communities will respond to temporal changes in water availability. To do this, we need to understand how drought affects individuals depending on their size, developmental stage, or associations with other plants. The investigators will experimentally reduce the amount of rainfall received by natural populations of the semi-desert herbaceous perennial Cryptantha flava by erecting temporary shelters during spring rainstorms. The study is based on data collected during a natural drought year indicating that larger plants are more severely affected by drought than smaller plants. Comparisions will be made of survival, growth and flowering of individuals of different sizes and in different microhabitats, under shrubs or in the open, both in areas where water has been reduced and in areas receiving natural rainfall. These demographic data will be supplemented by measurements of water use, leaf nitrogen content, and photosynthesis. These sorts of measurements will help to determine why individuals respond to changes in water availability as they do. The experimental reduction in water will be repeated spatially and in two different years. Demographic and physiological measurements will be taken on the same individuals in the year before drought, the drought year, and the year afterwards. This replication of the experiment is important because natural variation in rainfall is likely to occur during the experiment. The study should also lead to identification of lingering effects that extend beyond the drought year itself.