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

这是美国国家科学基金会生物学博士后研究奖学金，隶属于生物馆藏研究项目。这位名叫娜奥米·施瓦茨（Naomi Schwartz）的研究员正在进行研究，并接受以创新方式利用生物标本的培训，她的导师是明尼苏达大学（University of Minnesota）的詹妮弗·鲍尔斯（Jennifer Powers）。这名研究员的研究探讨了季节性，特别是降雨的时间，如何影响季节性干燥的热带森林中的植物利用水分的方式。一些干燥的森林经历了一个非常多雨的雨季，然后是一个几乎没有降雨的旱季，而另一些森林经历了低降雨量，但全年持续降雨，还有一些森林有两个明显的旱季。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有弹性。然而，我们仍然不了解季节性如何影响植物的水分利用。这一点很重要，因为气候变化已经引起了降雨季节性的变化和干旱的增加，而我们无法预测这些变化将如何影响季节性干旱的热带森林。这名研究员正在使用来自拉丁美洲各地的植物标本馆的藏品，这些标本被用来测量与水利用有关的植物特征，还使用卫星图像来观察季节性、光合作用和植物生长之间的联系。就更广泛的影响而言，这位研究员正在训练学生使用植物标本和卫星图像进行全球变化研究，并将她的研究结果纳入其他科学家可以使用的地球系统模型中。由于降雨情况在时间和广泛的地理尺度上有所不同，了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必要的空间尺度数据，以涵盖一系列降雨情况。该研究员的研究通过使用植物标本收集和遥感数据来解决这一挑战：这两种数据都非常适合分析广泛的空间和时间尺度上的生态模式，但很少结合到一个综合研究计划中。该研究员在整个新热带地区的四个植物标本馆测量与植物标本用水有关的性状，并利用这些测量来评估季节性降雨如何影响季节性干燥热带森林中物种内部和物种之间的性状变化。她还利用遥感技术绘制叶片物候和生产力图，以评估它们如何受到降雨季节性的影响。利用植物标本馆标本研究植物水力功能相关的一系列性状的研究很少，本研究在证明利用植物标本馆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.