LTER: Manipulating drivers to assess grassland resilience

点击翻译按钮获取中文摘要

Grasslands provide many benefits to society. In the eastern portion of the Central Plains, tallgrass prairie is the most common type of grassland. Tallgrass prairies once supported vast herds of bison and elk, and now support cattle ranching. Native prairie grasses are highly nutritious for cattle and can withstand frequent grazing, making tallgrass prairie the most productive rangeland in the United States. Tallgrass prairies also provide habitat for commercially important game species including deer, turkey, and waterfowl. Additionally, the prairies regulate water and nutrient cycles, and help store carbon. Remaining tallgrass prairie is threatened by invasive species, climate change, and expansion of woody plants. Sustainable management of tallgrass prairies requires a deep understanding of how these threats affect species, water, and nutrient cycling. Decades of research at the Konza Prairie Long-Term Ecological Research (LTER) site in Kansas have provided a deep understanding of how the prairie responds to environmental changes of many kinds. New research will focus on ecological resilience, identifying how plants and animals respond to natural disturbances (fire and grazing) and to the more recent challenges imposed by climate shifts and invasion of woody plants. This work will inform grassland restoration, management and conservation efforts throughout the Great Plains. Konza scientists will be active in education and outreach activities. For example, the Konza Environmental Education Program provides activities for thousands of K-12 students every year, illustrating the societal value of collecting long-term data. Konza scientists also provide community outreach and engagement for the public, land managers, conservationists, and policy-makers.Since 1980, the Konza Prairie LTER site has investigated how key drivers of grasslands globally - fire, grazing, and climatic variability - interact to influence tallgrass prairie structure and function. The conceptual framework of this renewal award builds on long-term studies, reflects the increasing complexity of research questions developed over the history of the site, and explicitly recognizes that tallgrass prairie pattern and process result from human alteration of ecological drivers at local (e.g., land use and management), regional (e.g., nutrient inputs) and global (e.g., climate change) scales. This research leverages long-term, watershed-scale manipulations of fire frequency and grazing by large ungulates, coupled with numerous plot-scale manipulations to test ecological theory and address timely questions regarding grassland responses to multiple, interacting global changes. Specifically, researchers will focus on mechanisms underlying sensitivity and resilience of ecosystem states in mesic grasslands. New research will utilize the array of ecosystem states that have emerged from previous landscape manipulations to refine the understanding of sensitivity, resilience, and ecosystem state change in tallgrass prairie. The research comprises four thematic areas: 1) continued watershed-level manipulations of historical drivers (fire and grazing), 2) experimental manipulations of global change drivers, 3) cessation or reversal of selected drivers to assess legacies, and 4) human intervention. Collectively, Konza Prairie research will advance ecological theory and improve our mechanistic understanding of ecosystem state changes by manipulating key drivers to alter ecological states while employing new analytical approaches to augment the value of Konza LTER’s long-term data sets. The research will provide new information critical for understanding, managing, and conserving grasslands globally, while concurrently addressing fundamental ecological questions to explain grassland dynamics in a changing world.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.