Browsing by Author "Larkin, Daniel J."
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Item Can Co-Grazing Waterfowl Reduce Brainworm Risk for Goats Browsing in Natural Areas?(EcoHealth, 2022) Marchetto, Katherine M.; Linn, Morgan M.; Larkin, Daniel J.; Wolf, Tiffany M.Goats browsing in woodlands, whether for livestock production goals or vegetation management (e.g., targeted grazing to control invasive plants), are at risk of meningeal worm ( Parelaphostrongylus tenuis ) infection. Indeed, up to 25% incidence has been observed in goats employed in vegetation management. Infection, which occurs via the consumption of an infected gastropod intermediate host, is potentially deadly in goats. We experimentally tested whether co-grazing with waterfowl could reduce goats’ exposure via waterfowl consumption of gastropods. Gastropods were sampled in a deciduous woodland before and after the addition of goats alone, goats and waterfowl, or a control with no animal addition. We found that goats browsing on their own increased the abundance of P. tenuis intermediate hosts; however, when goats co-grazed with waterfowl, these increases were not observed. Importantly, waterfowl did not significantly affect overall gastropod abundance, richness, or diversity. Thus, waterfowl co-grazing may effectively reduce goat contact with infectious gastropods without detrimentally affecting the gastropod community. While co-grazing goats with waterfowl may decrease their P. tenuis exposure risk, additional research is needed to confirm whether waterfowl can actually lower P. tenuis incidence.Item Complete Data and Analysis for: Niche models differentiate potential impacts of two aquatic invasive plant species on native macrophytes(2021-01-22) Verhoeven, Michael R.; Glisson, Wesley J.; Larkin, Daniel J.; michael.verhoeven.mrv@gmail.com; Verhoeven, Michael R; Minnesota Aquatic Invasive Species Research CenterThe goal of our study was to elucidate the mechanisms by which two invasive aquatic plant species (Myriophyllum spicatum and Potamogeton crispus) interact with native plant communities in lakes in Minnesota, USA. We used an observational dataset of aquatic plant occurrences—and associated light availability, depth, and temperature—to construct probabilistic models of the ecological niches of 34 aquatic plant species. We then compared shared-ness of these niches between the two invasive aquatic plants and 32 native species to infer the degree of direct competitive interaction. This repository contains the complete dataset as a comma-separated-value file and Program R code necessary to replicate the data prep, exploration, analysis, and visualizations presented in the manuscript.Item Complete data and code to generate datasets in: Occurrence and environmental data for aquatic plants of Minnesota from 1999-2018(2024-07-15) Verhoeven, Michael; Larkin, Daniel J.; michael.verhoeven.mrv@gmail.com; Verhoeven, Michael; Minnesota Aquatic Invasive Species Research Center (MAISRC); Fisheries Systems Ecology LabA dataset (and multi-scale aggregations thereof) of point-level occurrences, relative abundances, and associated environmental data for macrophytes (freshwater plants) across Minnesota. The data encompass 3,194 surveys of 1,520 lakes and ponds performed over a 19-year timespan. A total of 372,091 points were sampled, across which 231 taxa were recorded. Macrophyte occurrence data and depth, as well as point-level relative-plant-abundance measures for a subset of surveys, were collated, cleaned, and joined to geospatial data and Secchi-depth measurements of water clarity, enabling light availability, a primary control on aquatic plant growth, to be estimated.Item Complete Data for: Desiccation tolerance of the invasive alga starry stonewort (Nitellopsis obtusa) as an indicator of overland spread risk(2021-10-13) Glisson, Wesley J.; Wagner, Carli K.; Verhoeven, Michael R.; Muthukrishnan, Ranjan; Contreras-Rangel, Rafael; Larkin, Daniel J.; wjglisson@gmail.com; Glisson, Wesley, J; Minnesota Aquatic Invasive Species Research CenterThe ability of invasive macrophytes to survive out of water, i.e., their desiccation tolerance, is an important indicator of capacity for spread to new waterbodies through overland transport. Invasion by the alga starry stonewort (Nitellopsis obtusa [Desv. in Loisel.] J. Groves; Characeae) in North America is likely driven via overland transport, but little is known regarding its ability to remain viable out of water. We conducted laboratory and outdoor experiments to evaluate desiccation tolerance of N. obtusa propagules, including single stem fragments, small and large clumps of fragments, and bulbils (asexual reproductive structures). Propagules were removed from water after 15 min to 5 d to identify desiccation thresholds. The data from these experiments are documented and available here for public availability and use.Item Data and code for analyses in "The Use of Weighted Averages with Hedges: Is it Worth It?"(2021-09-21) Buck, Robert J.; Fieberg, John R.; Larkin, Daniel J.; robert.j.buck@gmail.com; Buck, RobertItem The effectiveness of using targeted grazing for vegetation management: a meta-analysis(Restoration Ecology, 2021) Marchetto, Katherine M.; Wolf, Tiffany M.; Larkin, Daniel J.The use of targeted grazing to control undesired plants as a component of ecological restoration is gaining in popularity, but there is considerable uncertainty among land managers about the effectiveness of this approach. We synthesized existing literature on the use of livestock (ruminants, swine, and equids) to control undesired plants using a meta‐analysis to address questions about the effectiveness of the approach. Seventy studies matched our inclusion criteria; these comprised 86% peer‐reviewed journal articles and 14% gray literature. Studies were conducted in 17 countries but highly concentrated in the United States and Europe. Cattle, goats, horses, and sheep were used for vegetation management in the studies. Most target plant species were nonnative perennial forbs. Median study duration was 3 years, with a maximum of 10 years. We found that, overall, the use of targeted grazing significantly reduced undesired plants and significantly increased plant species richness. However, several important questions remain. In particular, further research is needed to differentiate temporary defoliation from actual plant mortality, to separate the contributions of native versus nonnative species to gains in plant species richness, and to address longer term outcomes following grazing cessation.Item Goat Digestion Leads to Low Survival and Viability of Common Buckthorn (Rhamnus cathartica) Seeds(Natural Areas Journal, 2020) Marchetto, Katherine M.; Heuschele, D. Jo; Larkin, Daniel J.; Wolf, Tiffany M.The use of goat browsing for invasive plant management is growing in the United States, but many questions remain about the efficacy of goat browsing for invasive plant control. One common concern of land managers and other stakeholders is whether goats can spread invasive plants through endozoochory (seed dispersal via ingestion and excretion in feces). We evaluated this possibility using common buckthorn (Rhamnus cathartica), an invasive shrub for which goats are often employed as a control method. Goats were fed buckthorn berries, and their feces were collected and examined at 24 hr, 48 hr, and 72 hr post-ingestion for intact seeds that survived gut passage. A low proportion of buckthorn seeds (2%) made it through the goat digestive system intact. Of these, only 11% remained viable, compared to 63% viability of control seeds. We conclude that consumption of buckthorn fruits by goats effectively destroys seeds, indicating low risk of dispersal via gut passage. To put these results in context, and provide more guidance for land managers, we additionally reviewed literature investigating seed recovery following ingestion by goats. Based on a synthetic analysis across 28 plant species, we found that seeds >4 mm long were unlikely to be recovered from feces intact, while smaller seeds posed higher dispersal risk.