NSF Postdoc Fellowship in Biology FY 2017: Scaling up impacts of rainfall seasonality on tropical forest composition and function from herbarium collections and remote sensing data

这是NSF生物学博士后研究奖学金，项目是使用生物收藏进行研究。这位名叫内奥米·施瓦茨的研究员正在进行研究，并接受以创新方式利用生物收藏的培训，并由明尼苏达大学的珍妮弗·鲍尔斯指导。这位研究员的研究探索了季节性，特别是降雨的时间，如何影响季节性干燥热带森林中的植物如何利用水分。一些干燥的森林经历了一个多雨的湿润季节，然后是一个几乎没有降雨的干燥季节，而另一些森林全年降雨量很少，但持续不变，还有一些森林有两个截然不同的干旱季节。降雨量的这些差异可能会影响植物利用水分和应对干旱的方式。例如，适应严重季节性干旱的物种可能对未来的干旱更具弹性。然而，我们仍然不了解季节性是如何影响植物水分利用的。这一点很重要，因为气候变化已经导致降雨季节性的变化和干旱的增加，我们无法预测这些变化将如何影响季节性干燥的热带森林。这位研究员正在使用拉丁美洲各地收集的植物标本，这些植物被用来测量与水分利用有关的植物特征，以及卫星图像来观察季节性、光合作用和植物生长之间的联系。在更广泛的影响方面，该研究员正在培训学生使用标本收藏和卫星图像进行全球变化研究，并将她的结果纳入其他科学家可以使用的地球系统模型中。由于降雨制度在时间上和广泛的地理尺度上都有所不同，理解季节性如何影响热带森林的组成和功能的一个关键挑战是收集空间尺度上的数据，以涵盖一系列降雨制度。这位研究员的研究通过使用来自标本收藏和遥感的数据来解决这一挑战：这两种方法都非常适合分析广泛的时空尺度上的生态模式，但很少结合到一个综合的研究计划中。这位研究员正在对新热带地区四个草本植物的植物标本进行与水分利用相关的特征测量，并利用这些测量结果来评估降雨季节性如何影响季节性干燥热带森林物种内和物种之间的特征变化。她还使用遥感来绘制树叶物候和生产力图，以评估降雨季节性对它们的影响。很少有研究使用标本标本来检验与水力功能有关的一系列特征，拟议的研究在论证利用标本标本研究植物功能生态学和全球变化的可行性方面做出了重大贡献。

This is an NSF Postdoctoral Research Fellowship in Biology, under the program Research Using Biological Collections. The fellow, Naomi Schwartz, is conducting research and receiving training that utilizes biological collections in innovative ways, and is being mentored by Jennifer Powers at the University of Minnesota. The fellow's research explores how seasonality, in particular the timing of rainfall, affects how plants use water in seasonally dry tropical forests. Some dry forests experience a very rainy, wet season followed by a dry season with virtually no rainfall, while other forests experience low, but constant, rainfall throughout the year, and still other forests have two distinct dry seasons. These differences in rainfall could affect the way plants use water and cope with drought. For example, species that are adapted to severe seasonal drought may be more resilient to future droughts. However, we still do not understand how seasonality affects plant water use. This is important, because climate change is already causing shifts in rainfall seasonality and increases in drought, and we cannot predict how these changes will affect seasonally dry tropical forests. The fellow is using herbarium collections from across Latin America, which are being used to measure plant characteristics related to water-use, as well as satellite imagery to observe links between seasonality, photosynthesis, and plant growth. In terms of broader impacts, the fellow is training students in using herbarium collections and satellite imagery for global change research, and incorporating her results into earth system models that other scientists can use.Because rainfall regimes vary temporally and over broad geographic scales, a key challenge to understanding how seasonality affects composition and function in tropical forests has been collecting data at the spatial scales necessary to encompass a range of rainfall regimes. The fellow's research addresses this challenge by using data from herbarium collections and remote sensing: both are uniquely suited to analyzing ecological patterns across broad spatial and temporal scales but are rarely combined into an integrated research program. The fellow is measuring traits related to water use on plant specimens at four herbaria throughout the Neotropics, and using these measurements to assess how rainfall seasonality affects trait variation within and across species in seasonally dry tropical forests. She is also using remote sensing to map leaf phenology and productivity, to assess how they are influenced by rainfall seasonality. Few studies have used herbarium specimens to examine a suite of traits related to hydraulic function, and the proposed research is making major contributions in terms of demonstrating the feasibility of using herbarium collections for study of plant functional ecology and global change.