SG: Demographic drivers of plant community response to fire: Re-evaluating the relative importance of survival vs. reproduction

在19世纪欧美人定居之前，北美辽阔的草原每隔2-5年就会燃烧一次。这些频繁的火灾维持了草原的栖息地，并促成了今天草原上发现的鸟类、哺乳动物、昆虫和植物的多样性。大范围的栖息地丧失和火灾的扑灭正在导致仅存的几块草原上本土植物数量的下降。本土植物多样性的丧失促使许多美国人采取行动。当地、州和联邦政府的个人、企业和机构进行规定的焚烧，以改善栖息地并促进草原植物多样性。了解本土草原植物为什么能在火中茁壮成长，对于实现这些管理目标至关重要。除了分享将促进关于火灾和植物种群的基本科学知识的成果外，研究人员还将与土地管理人员、保护从业者、政策制定者和公众分享实用信息，以帮助他们更好地决定燃烧草原的频率，以实现他们的管理目标。除了传播科学成果和建议，该项目还将为一名博士后研究员和两名大学生提供研究经验和培训，以及明尼苏达州和芝加哥植物园的高中生、中学科学教师和保护研究志愿者参与的机会。该研究项目将调查火灾如何维持明尼苏达州西部本土多年生植物的健康种群。科学家们对火有两个主要假设：一方面，火可能帮助本土植物竞争和生存；另一方面，火可能帮助植物开花、授粉和产生种子。这两个假说都有证据，生存和繁殖都是维持种群所必需的，但火对每个过程有多大影响仍然是一个悬而未决的科学问题。研究人员将验证这一假设，即火灾后同步开花的生殖益处有助于促进种群增长，防止当地物种灭绝。他们将在30个草原上随机分配烧伤处理，在那里，他们将1)检查火灾对先前研究的紫锥花种群授粉和繁殖的影响，2)进行种子添加实验，以表征火灾对种子萌发和幼苗存活的影响，3)开发模型来量化火灾对紫锥菊种群增长的影响，以及4)估计火灾对其他三个广泛分布的草原物种的交配和繁殖的影响。这项裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Before European-American settlement in the 1800s, the vast grasslands of North America burned every 2-5 years. These frequent fires maintained grassland habitat and contributed to the diversity of birds, mammals, insects, and plants found in prairies today. Widespread habitat loss and the elimination of fire are causing native plant populations to decline in the few prairie patches that remain. The loss of native plant diversity has motivated many Americans to take action. People, businesses, and agencies of local, state, and the federal government conduct prescribed burns to improve habitat and promote prairie plant diversity. Understanding why native prairie plants thrive with fire is essential for achieving these management goals. In addition to sharing results that will advance the fundamental scientific knowledge about fires and plant populations, the researchers will share practical information with land managers, conservation practitioners, policy-makers, and the public to help them make better decisions about how frequently to burn prairies to achieve their management goals. In addition to disseminating scientific results and recommendations, this project will provide research experience and training to a postdoctoral researcher and two college students, as well as opportunities for engagement by high-school students, secondary-school science teachers, and conservation research volunteers in Minnesota and at the Chicago Botanic Garden.This research project will investigate how fire maintains healthy populations of native perennial plants in western Minnesota. Scientists have two main hypotheses about fire: on one hand, fires may help native plants compete and survive; on the other hand, fires may help plants flower, get pollinated, and produce seeds. Evidence exists for both hypotheses and both survival and reproduction are necessary to maintain a population, but how much fire influences each process remains an open scientific question. The researchers will test the hypothesis that the reproductive benefits of synchronized flowering after fire help promote population growth and forestall local extinctions. They will randomly assign burn treatments in 30 prairies, where they will 1) examine the effects of fire on pollination and reproduction in previously-studied populations of a purple coneflower, Echinacea angustifolia, 2) conduct a seed addition experiment to characterize the influence of fire on seed germination and seedling survival, 3) develop models to quantify effects of fire on Echinacea population growth, and 4) estimate fire effects on mating and reproduction in three other widespread prairie species.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.