Protecting water quality, biota, and ecosystem services of streams (cumulatively referred to as stream health) while increasing food production is a major global challenge. One way to balance these often-competing interests is through the installation of agricultural conservation practices, such as excluding livestock from streams via fencing and adjusting grazing patterns. However, conservation practices often do not improve stream health as expected. Failure to achieve stream health outcomes may be due to biophysical (e.g., conservation practices are not appropriate for the landscape) or social reasons (e.g., agricultural producers are not willing to use conservation practices). Therefore, the goal of my dissertation research was to understand factors influencing effectiveness of conservation practices using an interdisciplinary approach that integrates ecological engineering, ecology, and social science. My research focuses on southwest Virginia, a karst region where cattle grazing is common. In the introduction, I developed a social-ecological framework that outlines how the natural and social sciences can be used to guide effective placement and implementation of conservation practices and explain why interdisciplinary approaches are often necessary due to social-ecological connections that influence efficacy (i.e., feedbacks, heterogeneity, time lags, and thresholds). In Chapter 1, I modeled pollutant transport to characterize watershed features that contribute disproportionate amounts of pollutants to streams. I found that water, and associated nitrate, is primarily entering streams through subsurface pathways, whereas sediment is entering the stream through streambank erosion. Therefore, a combination of conservation practices that stop nitrogen at its source (e.g., nutrient management plans) and stabilize streambanks (e.g., fenced riparian buffers) could be useful for protecting stream health. For Chapter 2, I sampled water quality, habitat, and macroinvertebrates from 31 streams within sub-watersheds that span a range of pollutant yields, conservation practice densities, and agricultural land use extent to understand the pathways through which conservation practices influence stream health. Agricultural land use increased total nitrogen and decreased macroinvertebrate diversity, but conservation practices stabilized nitrogen and improved bank stability. Despite such improvements, adverse effects on water quality and habitat still limited the biotic assemblage. Therefore, innovative conservation practices, higher densities of existing practices, or allowing more time for the effects of existing practices to improve water quality and habitat may be required to achieve stream health goals. For Chapter 3, I surveyed producers to understand if they continue to use their conservation practices after their cost-share contracts end (i.e., persistence) and factors that influence persistence. Persistence was most strongly related to producers' attitudes towards the conservation practice, producers' motivations, and practice durability. Therefore, persistence could be encouraged by using producers' motivations to focus messaging on ways conservation practices are achieving producers' goals and allocating more funding to practice maintenance. Overall, my interdisciplinary approach led to a greater understanding of pollutant dynamics, the pathways through which conservation practices influence stream health, and social constraints to persistence. This knowledge can inform what conservation practices may be most effective and strategies to keep appropriate practices on the landscape long enough to achieve stream health goals. / Doctor of Philosophy / As farmers work to feed a growing worldwide population, streams can inadvertently receive pollution, like excess sediment and nitrogen. Too much sediment can clog the gills of aquatic animals and reduce their habitat, and too much nitrogen can cause excessive plant growth and decrease the amount of oxygen in the water. The cumulative effects of pollution from farming can result in streams being unable to support human uses such as clean drinking water and fishing opportunities. To increase food production while protecting streams, government agencies help farmers pay for the costs of using conservation practices that can reduce pollution. Examples of conservation practices include keeping livestock out of streams with fences, ensuring the ground is covered with plants in between planting crops, and developing a plan for the maximum amount of fertilizer that can be used. Unfortunately, conservation practices are sometimes ineffective, and streams still become polluted despite their use. My goal was to understand why some conservation practices are ineffective and how conservation practices might be improved for southwest Virginia. In the introduction, I developed a framework that illustrates how connecting the natural and social sciences can improve conservation practice efficacy by guiding planning and placement of new practices. In Chapter 1, I used a computer program to simulate pollution within streams so that I could understand which locations have the greatest amount of pollution and why. I found that nitrogen typically enters streams through the water in the soil rather than water running over the land surface and that sediment mostly enters the stream through erosion of the streambanks. These results suggest that conservation practices such as limiting the amount of nutrients placed on the landscape could be especially effective for reducing nitrogen pollution, whereas building fences to exclude cattle from streams and planting trees along streams can help reduce sediment pollution. For Chapter 2, I visited 31 streams in southwest Virginia that had varying amounts of pollution and conservation practices and collected water quality, habitat data, and aquatic insects. All these metrics are good indicators of pollution, but aquatic insects are particularly excellent indicators because their populations respond to cumulative changes in habitat and water quality. Streams with more conservation practices did not exhibit more diverse insect communities but did show stabilized water quality and habitat. These results indicate that the types of conservation practices currently used are not completely protecting streams and farmers may need to use more practices, new types of practices, or use their current practices for longer periods of time. For Chapter 3, I surveyed farmers to find out if they continue to use their conservation practices after funding from agencies ends, as well as their motivations for their actions. Farmers indicated that they were more likely to continue using conservation practices if their goals for using the practice were achieved and that they had difficulty keeping fences and trees from being destroyed by floods and wildlife. Government agencies could increase continued use of conservation practices by showing farmers how the practices are achieving their goals and by providing more funding to maintain practices. By combining research from several fields of study, I was able to better understand which conservation practices would be most effective in protecting streams and new ways to support farmers in using conservation practices.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/120965 |
| Date | 19 August 2024 |
| Creators | Mouser, Joshua Braden |
| Contributors | Fish and Wildlife Conservation, Angermeier, Paul L., Brown, Bryan L., Czuba, Jonathan A., Ciparis, Serena, Dayer, Ashley A. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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