Browsing by Subject "Ecosystem services"

Now showing 1 - 4 of 4
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    Assessing Biodiversity in Summer Cover Crop Rotations for Beneficial Arthropod Conservation
    (2022-05) Candelaria-Morales, Naomy
    Intensive vegetable crop practices can have detrimental effects on soil health, draining soil of organic matter reserves and necessitating nitrogen (N) inputs. These amendments can support crop productivity but may have considerable environmental consequences including overfertilization, water eutrophication, and reduce fauna (Agostini et al., 2010). In addition, many vegetable crop rotations are characterized by high plant density but low beneficial arthropod and pollinator habitat diversity (Carreck and Williams, 2001). Habitat simplification may cause declines in beneficial arthropods, which can lead to insufficient pollination services and increased pest pressure (Hogg et al., 2011; Wilson et al., 2018). Out of numerous arthropod services, pollination, pest control, dung burial and wildlife nutrition have been estimated to value at least $57 billion USD (Forister et al., 2019). Because of sheer amount of agricultural land, comprising over 40% of all U.S. land, agricultural ecosystems present valuable opportunity in maintaining biodiversity (USDA, 2012). Constant forage availability from early spring to late summer is particularly imperative for the survival of social insects with long-lived colonies, such as bees (Carreck and Williams, 2001). The use of cover crops can expand the seasonal availability of floral resources in agroecosystems (Hooks et al. 1998; Landis et al. 2005). In a two-part study, this research investigated the effects of summer-planted cover crops on soil nutrient contributions and beneficial arthropod density, diversity, richness and evenness. Part one consisted of a one-year (2019) field trial study where nine treatments, each containing one to seven species of cover crops, were evaluated for flowering, aboveground biomass production and nitrogen (N) content, soil-N contribution after biomass incorporation, and beneficial arthropod visitation. A seven-species mix composed of oat (Avena sativa L.), field pea (Pisum sativum subsp. Arvense L.) and 5 clover species (Trifolium spp.) added the largest amount of biomass (8747 kg/ha). Likewise, this mix contributed the most organic N (265.6 kg N/ha) and maximum soil -N subsequently increased after biomass incorporation (10.9 mg -N/kg of soil). Part two consisted of a two-year (2020-2021) study evaluating the ability of two rotational systems of summer cover crop species, selected from 2019 trials, to provide key multifunctional ecosystem benefits to vegetable crop production. The first system was an early cover crop planting followed by a broccoli cash crop, and the second system consisted of an early planting of spring lettuce followed by a late summer cover crop planting. In all three years, buckwheat (Fagopyrum esculentum Moench) and phacelia (Phacelia tanacetifolia Bendth.) monoculture produced most abundant floral resources. Beneficial arthropods observed included pollinators (native, honey and bumblebees), predators (syrphid flies and minute pirate bugs), and parasitoids. Increased floral diversity was associated with abundance of flies in the family Syrphidae. Phacelia monoculture was most attractive for bees in the families Apidae and Halictidae, both of which may provide pollination services. These results highlight floral visitation patterns as an indicator for beneficial arthropod community support and conservation. Summer-planted cover crops are an underexplored rotation option for organic farming systems in the Upper Midwest and may support a wide range of ecosystem services including increases in available soil N and beneficial arthropod services.
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    Climate change, forest composition, and outdoor recreation in northeastern Minnesota
    (2022-09) Bakshi, Baishali
    Climate change will likely result in a change in the composition of northern Minnesota forests by the end of the century, affecting outdoor recreation, which is a valuable ecosystem service as well as a key economic driver for the state with over $4 billion in annual expenditures in hunting, fishing, and wildlife viewing. Yet, the links between climate change, forest composition, and outdoor recreation have not been well studied. Current research finds that deer can also affect the links between climate change, forest composition, and outdoor recreation. In this dissertation, I examine and evaluate the links between these four main variables: climate change, forest composition, deer, and outdoor recreation, and a variety of other relevant predictors, using a combination of econometric modeling and spatial analysis applied to region-specific data in the Laurentian Mixed Forest Province (LMF) of northern Minnesota. My results improve understanding of these complex relationships to better inform Minnesota’s climate adaptation strategies and contribute to the literature on ecosystem services.
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    Land cover characteristics in the Karst regon of southeastern Minnesota.
    (2009-11) Williams, Mary Alice
    Anthropogenic land-use activities can affect regional biophysical processes and functioning of neighboring land areas impacting the human and natural communities found in these areas. Karst landforms add complexity to land-use management. The term "karst" describes predominately limestone and dolostone landforms weathered primarily through a chemical dissolution process. Over geologic time, karst features including sinkholes, bedrock springs and fractures, sinking streams and caves form on and under the land surface. Studies that further our understanding of land cover and land use, especially in sensitive land areas can inform and improve land management and policy development for those areas. Through three projects, this thesis examined land and land-use characteristics in a regional karst landscape. Physical spring characteristics were analyzed to determine whether a subset of spring characteristics can discriminate springs into bedrock units or aquifer units. A subset of characteristics was found that discriminated the springs into both bedrock units and aquifer units. Springs had a clumped distribution on the landscape with most springs found at low elevations. For the second project, land pattern metrics were examined for a county-delineated land area and compared with pattern metrics in the major watershed overlying that county area. Differences between patterns of variation in metrics for the watershed versus the county area including greater fragmentation in the county landscape, fewer components of variation in the watershed and greater importance of land cover diversity in the watershed. For the last project, local municipal protection of regional natural resource processes was examined by determining the extent of local policy coverage on landscape functions and ecosystem services. Current coverage and gaps were identified. Policy changes directed at incorporating landscape functions into land-use planning were presented. This research provides new information about spring characteristics, land pattern metrics, and policy coverage of natural resources and ecosystem services, contributing to the accumulation of knowledge of land use and land cover characteristics, especially for karst regions, including that found in southeast Minnesota.
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    Twin Cities urbanization and implications for urban forest ecosystem services.
    (2012-05) Berland, Adam Michael
    Urbanization affects ecological structure and function by impacting the provision of ecosystem services, or benefits we derive from the environment. It is broadly acknowledged that ecosystem services should be formally considered in land management decisions, but inadequate scientific understanding of urban ecological systems is a key obstacle to achieving this goal. In this dissertation, I address this shortcoming by assessing the relationships between urbanization and the urban forest, a key urban ecological component. The three studies described here demonstrate spatial and temporal effects of urbanization on urban forest structure, function, and value in Minnesota's Twin Cities Metropolitan Area. In the first study, I used historical air photos to analyze past trends in tree canopy cover related to urbanization and other land cover changes. Urbanization events generally reduced tree canopy cover, but urban sites rapidly afforested following development. Older urban neighborhoods typically had higher tree canopy cover than newly developed areas. In the second study, I used factor analysis on a suite of urbanization indicator variables to derive an urbanization gradient that is more sophisticated than a simple urban-rural distance-based gradient. This synthetic gradient was strongly related to more types of urban forest structural variables than the distance-based gradient, highlighting the influence of secondary urbanization trends on urban forest structure. In the final study, I stratified the study area by property parcel land use, and compared estimated urban forest structure, function, and value across land use classes. Residential and undeveloped areas both had higher urban forest values than non-residential developed areas, but were not statistically different from one another. This study showed which types of urban land uses promote good urban forest structure and function, and the results can be used to guide future urban forest study designs. All three studies demonstrate the need to consider complexities associated with human-environmental systems. Two major themes were the importance of temporally lagged tree growth and nonlinear urban-ecological relationships. By making these complexities more visible, this research will improve the design of future work, so that we can develop a more complete and nuanced understanding of the effects of urbanization on the urban forest.