RAPID: The effects of wildfire on an ecohydrological experiment and the role of abiotic drivers of resistance and resilience in sagebrush-steppe landscapes

美国西部野火的频率和强度都在上升。在大盆地地区，火灾促进了非本地一年生草的入侵，进一步延续了火灾循环。火灾和植物入侵威胁着许多本地物种的栖息地、草原的生产力和人类的生计。对火灾如何影响植物物种、土壤资源和火灾后生态系统恢复的了解仍然有限。在美国西部的山艾草草原生态系统中，确定控制火灾后恢复的植物、土壤和气候条件将有助于查明是什么使这些生态系统具有恢复力或易受火灾影响。该项目将评估火灾前土壤水分和养分有效性的差异如何决定火灾后本地和入侵植物物种的平衡。土壤养分和水分的动态变化也许可以解释为什么有些地方比其他地方更容易被入侵。研究人员和该地区的牧场管理者之间有着密切的联系。在这项研究中获得的知识将有助于我们了解美国西部容易发生火灾的草原。该项目将培养几名早期研究人员，包括一名博士后和本科生。该项目将研究爱达荷州25年的生态水文实验，该实验控制湿度、土壤深度和植物群落组成。该实验在2019年的一场大型野火中进行，为测试火灾前的非生物和生物条件如何影响野火后对入侵物种的抵抗力提供了一个独特的机会。这个实验将检验一个关于非本地一年生草如何入侵本地生态系统的关键假设。人们的期望是，非原生草的初次种植会进一步改变土壤，从而改变生态系统。为了验证这一假设，在植被恢复的初始阶段，需要立即进行几项测量：(1)植被组成和覆盖，(2)土壤水分和养分有效性，(3)土壤水分和养分运动。这些即时测量将有助于了解植物在裸露的土壤中重新定居时土壤氮和水的可用性会发生什么变化。这将使我们能够从机制上了解是什么驱动了山艾草草原生态系统中植物群落恢复的差异。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Wildfire frequency and intensity are rising across the western United States. In the Great Basin region, fire promotes invasion of non-native annual grasses that further perpetuate the fire cycle. Fire and plant invasion threaten the habitat of many native species, the productivity of grasslands, and human livelihood. Understanding how fire affects plant species, soil resources, and ecosystem recovery following fire remains limited. In the sagebrush steppe ecosystem of the western United States, identifying the plant, soil, and climate conditions that control post-fire recovery would help pinpoint what makes these ecosystems resilient or vulnerable to fire. This project will evaluate how differences in soil water and nutrient availability before a fire determine the balance of native and invasive plant species after a fire. The dynamics of soil nutrients and water might explain why some sites are more likely to become invaded than other sites. There are strong connections between the researchers and rangeland managers in the region. The knowledge acquired in this study will help inform our understanding of fire-prone grasslands in the western United States. This project will train several early-career researchers, including a postdoctoral associate and undergraduate students.This project will study a 25-year ecohydrological experiment in Idaho that manipulates moisture, soil depth, and plant community composition. The experiment burned in a large 2019 wildfire, providing a unique opportunity to test how pre-fire abiotic and biotic conditions influence the resistance to invasive species after wildfire. This experiment will test a key hypothesis about how non-native annual grasses invade native ecosystems. The expectation is that the primary establishment of non-native grasses causes further changes to the soil that change the ecosystem. To test this hypothesis, several measurements need to be made immediately during the initial vegetation recovery phase: (1) vegetation composition and cover, (2) soil water and nutrient availability and (3) soil water and nutrient movement. These immediate measurements will help understand what happens to soil nitrogen and water availability as bare soil is recolonized by plants. This will allow mechanistic insight into what drives differences in plant community recovery in sagebrush steppe ecosystems.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.