4 research outputs found
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Synthesis Paper: Assessment of Research on Rangeland Fire as a Management Practice
Rangelands are fire-dependent ecosystems severely altered through direct fire suppression and fuels management. The removal of fire is a dominant cause of ecological sites moving across thresholds with the majority of North American rangelands currently showingmoderate or high departure from reference conditions. Recognizing the need to restore fire on rangelands and incorporate prescribed fire into management plans, the Natural Resource Conservation Service initiated the Conservation Effects Assessment Project (CEAP) to evaluate the validity current practices through peer-reviewed scientific literature. We updated the CEAP review and broadened the discussion of prescribed fire as a global management practice. We reviewed and summarized prescribed fire literature available through Web of Science using search terms in the title. The majority of literature (40%) evaluated plant responses to fire with fire behavior and management (29%), wildlife and arthropods (12%), soils (11%), and air quality (4%) evaluated less frequently. Generally, fire effects on plants are neutral to positive and the majority of negative responses lasted less than 2 years. Similarly, soil responses were recovered within 2 yr after burning. However, most studies did not report how long treatments were in place (62%) or the size of experimental units (52%). The experimental literature supporting prescribed burning is in need of greater managerial relevance that can be obtained by directly addressing spatial scale, temporal scale, and interaction with other disturbances, including drought and grazing. Reliance on information from single fires applied on small plots tracked for a relatively short time interval greatly constrains inferences and application to ecosystem management and information should be applied with caution. Therefore, conservation purposes need to incorporate temporal dynamics to the extent that this information is available. The complex interaction of scientific knowledge, social concerns, and variable policies across regions are major limitations to the successful and critical restoration of fire regimes. © 2016 The Society for Range Management. Published by Elsevier Inc. All rights reserved.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information
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Facilitation of an Exotic Grass Through Nitrogen Enrichment by an Exotic Legume
Invasive species control requires understanding the mechanisms behind their establishment and their interactions with other species. One potential ecosystem alteration influencing the establishment and spread of invasive species is anthropogenic nitrogen enrichment, from sources like introduced or invasive nitrogen (N)-fixing legumes, which can alter competition between native, non-native, and invasive plants. Kentucky bluegrass (Poa pratensis) and N-fixing yellow sweet clover (Melilotus officinalis) are exotic to the Great Plains and are currently invading and degrading native rangelands by altering ecosystem processes and displacing native plants. Therefore, we investigated how N enrichment from yellow sweet clover affects the aboveground biomass production of Kentucky bluegrass and western wheatgrass (Pascopyrum smithii), a native cool-season grass, the ranges of which overlap in the northern Great Plains. In a controlled greenhouse environment, we conditioned experimental pots by growing yellow sweet clover and terminating each plant after 8 wk. Conditioned soils contained ≈ 340% more plant-available N than untreated soils 2 wk after yellow sweet clover death. We then grew Kentucky bluegrass and western wheatgrass transplant seedlings in interspecific and intraspecific pairs in pots conditioned either with or without yellow sweet clover for 12 wk. Aboveground biomass production of both Kentucky bluegrass and western wheatgrass grown in interspecific and intraspecific pairs increased in conditioned soils. However, when grown together in conditioned pots, the increase in Kentucky bluegrass biomass relative to untreated pots (520%) was double that of the increase in western wheatgrass biomass (260%). Our results reveal that Kentucky bluegrass can use increased soil N to produce proportionally more aboveground biomass than western wheatgrass, a native grass competitor. Thus, our results suggest yellow sweet clover and other sources of N enrichment may facilitate the invasion of Kentucky bluegrass.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information
Arthropods and Fire: Previous Research Shaping Future Conservation
Fire is a natural process in grasslands that maintains an open canopy and creates variable vegetative structure and composition over time. Although there is a wealth of knowledge on plant and avian responses to fire in the Great Plains, there are few generalizations for arthropods. We conducted a literature review to synthesize research on arthropod responses to fire in the Great Plains to offer more insights to land managers, policy makers, and researchers. Overall, we found that there was variation in how arthropod communities responded to fire; metrics of both abundance and diversity were found to respond positively, negatively, or not at all. We then delved into two potential factors that might help us understand this important variation. First, we looked for effects from the amount of time since fire. Although much of the literature focused on arthropod responses to burning in the first 6 mo after fire, there were still both positive and negative results regardless of timeframe. We also hypothesized that taxonomy may provide insights and found that some orders tended to respond negatively (Araneae, Lepidoptera) or positively (Coleoptera, Orthoptera) to fire; however, responses were still variable and likely dependent on additional factors. To help enable managers to make better decisions about fire application, we used the literature to identify three traits-mobility, life stage, and feeding guild-that can predict responses to fire at a species level when research is lacking. Management recommendations vary on a species-by-species basis, but available research suggests that arthropod communities do not simply respond negatively to fire. Knowledge gaps remain concerning the origin of those community responses, particularly in terms of individual species' responses and specific mechanisms that allow individuals to persist after fire. Future research should focus on theoretical and applied basis for arthropod conservation using prescribed fire. © 2017 The Society for Range Management. Published by Elsevier Inc. All rights reserved.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information