GoalsThis project investigates how disturbance is used as a tool by managers to improve the quality of grasslands enrolled in the Conservation Reserve Program (CRP). To achieve this aim, we are tracking 1) soil, 2) plant, 3) pollinator, and 4) ground–dwelling macroinvertebrates response to the disturbances used by managers that serve as analogies for historical disturbance. These management practice disturbances are part of Conservation Reserve Program mid–contract management (MCM) and include burning, disking, interceding, herbicide, or some combination thereof.
The decision to use one or many of these approaches to fulfill MCM obligations requires landowners to weigh various economic, ecological, and social tradeoffs. By combining the ecological knowledge gained from our field investigation with knowledge generated from a statewide landowner survey, this work seeks to provide valuable information to private landowners, agency personnel and scientists interested in supporting smart land management decision–making.
Findings from a Nebraska statewide CRP survey support the prevailing wisdom that soil health and upland game bird habitat are ecosystem services highly valued by landowners. Landowners also strongly agreed that undesirable plant species are an ecosystem disservice associated with CRP enrollment. However, landowner management practices across the state may be undermining some these management outcomes –at least based on the results from our field experiment. Landowners use herbicide application as the second most common mid-contract management (MCM) practice, following interceding, which is typically used in conjunction with other practices including herbicide application. In our field experiment, herbicide application elicited high soil nitrogen levels, likely due to lack of plant uptake or due to microbial mineralization of soil organic nitrogen fueled by the herbicide used (soil bacteria can nominally metabolize glyphosate). Elevated soil nitrogen apparently selected for non-native, annual plants that are considered undesirable weedy species by the majority of managers and landowners. The herbicide treatment also shifted belowground communities towards bacteria, rather than fungus. Bacteria dominated belowground food webs are less resilient to drought, leakier nutrient retainers, and more sensitive to environmental pollutants such as heavy metals. Overall, herbicide application resulted in less desirable aboveground and belowground outcomes, revealing gaps between landowner identified objectives and practices as reported in the statewide CRP survey.
Principal Investigator(s)-Craig R. Allen, NE CFWRU
-Hannah E. Birgé
Graduate Student(s)-Hannah Birgé, Ph.D (2017)
Project DurationJune 2013 – August 2017
Funding-National Science Foundation IGERT Program
-Nebraska Game and Parks Commission
-United States Department of Agriculture Sustainable Agricuture Research & Education (SARE)