Quantifying the Invasive Grass-Fire Cycle and Implications for Carbon Storage in the Continental U.S.

该项目将调查非本地入侵草如何改变美国大陆一系列生态系统的火情和碳储存。通过探索入侵草如何影响野火，该项目将扩大对入侵物种如何影响生态系统功能方式的基本了解。通过量化与入侵和火灾相关的碳储量变化，该项目将提供一个关于草火循环如何影响生态系统碳储量的全国估计。该项目将通过量化与易着火的入侵草相关的野火风险来造福社会。通过强调以前被忽视的入侵草和相关野火的碳成本，该项目还将为易发生火灾的入侵草的管理和控制提供新的视角、见解和信息。非原生草入侵最不利的生态后果之一是改变了火灾制度。侵入性燃料的添加增加了火灾的频率，阻碍了本地生态系统的恢复。非本地物种的入侵和火灾制度的改变影响了从沙漠到草原到森林的土地覆盖类型。尽管数十种易着火的禾草入侵了整个美国大陆，但沙草（Bromus tectorum）仍然是唯一一个被量化了区域性草-火循环的物种，并且与入侵草相关的火灾变化相关的生态变化的碳后果只对同一物种进行了测量。进行该项目的研究人员将研究入侵草如何改变区域火灾周期，以及这些变化如何影响美国大陆的碳储量。他们将结合使用基于卫星的中分辨率成像光谱辐射计（MODIS）和可见光红外成像辐射计组件（VIIRS）传感器收集的易火入侵草发生地点的综合数据库，以识别改变区域火灾周期的入侵草。​他们将利用独立斜坡模型（PRISM）气候数据、航天飞机雷达地形任务（SRTM）地形数据、MODIS和美国地质调查局物候植被产品作为预测因子，对草害的潜在范围进行建模。研究人员将通过对三种目标物种的实地测量和对其他已知入侵草物种的文献综述，量化与草入侵相关的地上和地下生物量和土壤碳储量的变化，并将利用分布数据和潜在范围模型扩大这些场址水平的碳损失测量，以计算草-火循环的碳后果。通过整合这四个相关的项目组成部分，研究人员将对入侵草、火和碳循环之间的联系提供新的见解。

This project will investigate how non-native, invasive grasses alter fire regimes and carbon storage across a range of ecosystems in the continental U.S. By exploring how invasive grasses impact wildfire, the project will expand basic understanding of how invasive species affect the ways in which ecosystems function. By quantifying changes in carbon stocks associated with invasion and fire, the project will provide a national estimate of how the grass-fire cycle affects ecosystem carbon storage. The project will benefit society by quantifying wildfire risks associated with fire-prone invasive grasses. By highlighting the previously neglected carbon costs of invasive grasses and associated wildfires, this project also will provide new perspectives, insights, and information regarding the management and control of fire-prone invasive grasses.One of the most adverse ecological consequences of non-native grass invasion is the alteration of fire regimes. The addition of invasive fuels increases fire frequency and impedes the recovery of native ecosystems. The invasion of non-native species and altered fire regimes affect land-cover types ranging from deserts to prairies to forests. Although dozens of fire-prone grasses have invaded throughout the continental U.S., cheatgrass (Bromus tectorum) remains the only species for which a regional grass-fire cycle has been quantified, and the carbon consequences of ecological change associate with altered fire related to invasive grasses has been measured only for this same species. The investigators conducting this project will study how invasive grasses are altering regional fire cycles and how these changes affect carbon stocks in the continental U.S. They will combine a comprehensive database of fire-prone invasive grass occurrence locations with fire data gathered using satellite-based moderate-resolution imaging spectroradiometer (MODIS) and visible infrared imaging radiometer suite (VIIRS) sensors to identify invasive grasses that are altering regional fire cycles. They will model the potential range of grass infestations using parameter-elevation relationships on independent slopes model (PRISM) climate data, shuttle radar topography mission (SRTM) topography data, and MODIS and U.S. Geological Survey phenology vegetation products as predictors. The investigators will quantify changes in above- and below-ground biomass and soil carbon stocks associated with grass invasion using a combination of field measurements for three target species and literature reviews for other known invasive grass species, and they will scale-up these site-level measurements of carbon loss using the distribution data and potential range models to calculate the carbon consequences of the grass-fire cycle. Through integration of these four related project components, the investigators will provide new insights regarding the connections among invasive grasses, fire, and the carbon cycle.