Browsing by Subject "Native plants"

Now showing 1 - 4 of 4
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    Biological Control of Canada Thistle in Wetland Prairie Restoration
    (Minnesota Department of Transportation, 2007-10) Eichstaedt, Kari; Wyse, Donald; Johnson, Gregg
    Pseudomonas syringae pv. tagetis (Pst), a phytopathogenic bacterium, was evaluated as natural biological control agent for Canada thistle [Cirsium arvense (L.) Scop.]. Canada thistle patches exhibiting symptoms of Pst infection commonly occur along roadsides in association with perennial grasses and a grass litter layer. Field experiments were conducted to determine if grass and litter provide an environment that supports Pst infection of Canada thistle or if grass, litter, and soil collected from infected Canada thistle patches act as inoculum sources for Pst infection of Canada thistle. This experiment provides evidence that grass and litter are important components of the landscape that support the natural Pst infection of Canada thistle, and perennial grass competition has potential to manage Canada thistle in roadside rights-of-way and wetland restoration sites. A previously published Pst specific primer set was determined to require high Pst populations for detection.
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    Cost-Effective Roadside Revegetation Methods to Support Insect Pollinators
    (Minnesota Department of Transportation, 2022-08) Mitchell, Timothy; Verhoeven, Michael; Darst, Ashley; Evans, Elaine; Cariveau, Dan; Snell-Rood, Emilie
    Roadsides contain promising habitat for insect pollinators, yet roadside restorations can be expensive and are rarely evaluated for effectiveness. Where do we establish pollinator-friendly revegetation to maximize benefits? How effective are current revegetation practices at providing habitat for pollinators? We address these questions with two studies. Chapter 2 examines the impact of roadside-adjacent habitat that has been identified as pollinator-friendly for bumble bees. We use pollinator habitat maps to examine associations between the amount of nearby pollinator-friendly habitat and bumble bees (abundance and richness). We also regroup land covers to more specifically align with bumble bee habitat needs and compare the ability of both land cover categorizations to predict bumble bee metrics. This study can help refine predictors in mapping efforts to prioritize locations for pollinator habitat enhancements. Chapters 3 and 4 combine detailed insect and floral surveys of sites with known revegetation history to test efficacy of current revegetation methods for providing habitat for insect pollinators. We show which plants establish after seeding and how communities change as they age. We find that native flowering plants are more likely to establish in roadsides when they are planted, but native and non-native seeded sites converge in the plant community through time. Bumble bee and butterfly abundance and diversity is tied to flowering plant abundance and diversity, regardless of their status as native plants. This work identifies where pollinator-friendly restorations should be implemented and how current seeding practices could be modified to improve benefits to pollinators while reducing costs.
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    Effects of repeated early season herbicide treatments of curlyleaf pondweed on native macrophyte assemblages in Minnesota Lakes.
    (2010-09) Jones, Ajay Robert
    Non-native invasive species have the potential to cause various problems in small isolated ecosystems, these constraints are exemplified in the small, shallow, lakes of Minnesota. Curlyleaf pondweed (Potamogeton crispus L.) is one of the common occurring and most influential non-native invasive species in Minnesota. Characterized by its early spring growth and early summer senescence, curlyleaf has the ability to negatively affect native macrophyte growth by forming dense monotypic canopies in late spring and releasing nutrients in early summer. Because of the negative impact on natural ecosystems along with the problems curlyleaf can cause for people, there is serious interest in the management of curlyleaf. One management practice is the early season application of herbicides, where curlyleaf is targeted before it is capable of producing turions (propagules) and native plants are unlikely to be affected. We examined the response of native plant communities to spring herbicide treatments of curlyleaf pondweed from 2006 through 2009. Thirteen lakes were examined during our study; ten were treated with herbicide and three were used as nontreatment reference lakes. Plant communities were assessed in the littoral zone with the point intercept method in early spring (before treatment), late spring (after treatment) and mid summer (peak native plant growth). For each survey, approximately 40 random biomass samples were taken in each study lake to estimate plant biomass. To determine changes in native plant frequency and biomass throughout the course of consecutive annual treatments, we compared differences between treated and untreated lakes within years for August surveys and compared August surveys between years for treated or untreated lakes. Additionally, we examined inter-seasonal changes, comparing differences within and between treated or untreated lakes from May to June and June to August in every year. In the reference lakes, curlyleaf persisted at moderate to high frequencies over the four years, and no consistent changes in native plant frequencies were seen. Herbicide treatments proved effective for controlling curlyleaf, which decreased in frequency within 1 month following treatment for each year of the study. The total frequency of occurrence of native plants in August did not decrease in most of the treatment lakes between years. Native macrophyte species richness also showed little change with continued treatment, although shifts in abundance of some species were observed. August native plant biomass increased between 2006 and 2009 in most treatment lakes, whereas native biomass varied in untreated lakes. Much of the change in biomass was attributed to a single species in most treatment lakes. We observed increases of Chara spp. frequency and biomass in most treated lakes. However, multiple years of treatment may be needed to obtain increases in native plant abundance as the largest increases occurred after 3 years of treatment. Early-season lake-wide herbicidal treatments of curlyleaf pondweed can reduce curlyleaf occurrence and density without major harm to native plants. Significant inter-seasonal changes in frequency and biomass were observed in both treated and untreated lakes although differences were not observed between treated and untreated lakes. Native species richness increased from May to June and June to August in both treated and untreated lakes. The frequency of native plants increased between May and June but less so between June and August in both treated and untreated lakes. Conversely, native plant biomass increased from June to August more so than from May to June for both treated and untreated lakes. These findings suggest that early season growth primarily manifests in distribution and colonization, while late season growth results in increased biomass. Similarly, many plant species follow the same patterns as the overall native plants, although other plant species may have different frequency and biomass regimes throughout a single season. Despite the differences in native plant species, we did not see any major inter-seasonal detriment caused by the presence of curlyleaf pondweed in untreated lakes, or positive influence of herbicide treatment in treated lakes. These findings suggest that increases in native plant growth may occur only after several annual treatments.
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    Production Of Native Plants For Seed, Biomass, And Natural Products
    (2020-03) Freund Saxhaug, Katrina
    Native and naturalized perennial plants are important components of sustainable agricultural systems, providing a wide range of ecosystem services including marketable products. Although demand for these products is increasing, there is limited information on the establishment and production of native and naturalized perennial plants. Through field and greenhouse studies, four native and naturalized perennial plant species were evaluated for their seed yield, biomass yield, and phytochemical (natural product) production. Canada milk vetch (Astragalus canadensis L.), purple coneflower (Echinacea purpurea Moench [L.]), and showy tick trefoil (Desmodium canadense L.) were evaluated in the field for seed and biomass production over three consecutive years. Seed yield decreased in all three species over time, whereas biomass yields over time varied by species. Seed and biomass yields, on a per hectare basis, decreased as the number of rows decreased, and there was little effect of plant community richness or diversity. An untargeted metabolomics approach was taken to evaluate phytochemical production in purple coneflower tissues. Several bioactive compounds were provisionally identified in purple coneflower tissues, and seed tissue possessed a similar profile to that of root. Although the plant community did not affect the overall metabolomic profile of purple coneflower, levels of specific compounds in leaf, stem, and root tissue were affected. Similar biomass yield and metabolomics approaches were applied to fireweed (Chamaenerion angustifolium (L.) scop., syn. Epilobium angustifolium L.) grown in a hydroponic system. Shoot dry weight increased logistically with increasing mineral concentration of the nutrient solution. Although the abundance of most provisionally identified compounds decreased with increasing mineral nutrient concentration, commercially-relevant oenothein B and miquelianin were not affected by mineral nutrient treatments. Native and naturalized perennial plants on the agricultural landscape can provide numerous ecosystem services, including marketable products such as seed for restoration plantings, biomass for fuel and forage, and bioactive phytochemicals for medicinal and supplemental purposes. In order to incentivize the establishment of native and naturalized perennials for such marketable products, research on the productivity of specific plants is needed. The research presented in this dissertation provides the groundwork for four native and naturalized Minnesota species.