Browsing by Subject "adaptive management"

Now showing 1 - 3 of 3
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    Factors Influencing Beaver (Castor Canadensis) Population Fluctuations, And Their Ecological Relationship With Salmonids
    (2019-08) Johnson-Bice, Sean
    Within the western Great Lakes (WGL) U.S. region (Michigan, Minnesota, Wisconsin), the ecological impacts that North American beavers (Castor canadensis) have on cold- water streams are generally considered to negatively affect salmonid populations where the two taxa interact. Here, we review the history of beaver-salmonid interactions within the WGL region, describe how this relationship and management actions have evolved over the past century, and review all published studies from the region that have evaluated beaver-salmonid interactions. Our review suggests the impact beavers have varies spatially and temporally, depending on a variety of local ecological characteristics. We found beaver activity is often deleterious to salmonids in low-gradient stream basins, but generally beneficial in high- gradient basins; and ample groundwater inputs can offset the potential negative effects of beavers by stabilizing the hydrologic and thermal regimes within streams. However, there was an obvious lack of empirical data and/or experimental controls within the reviewed studies, which we suggest emphasizes the need for more data-driven beaver-salmonid research in the WGL region. Resource managers are routinely faced with an ecological dilemma between maintaining natural environmental processes within cold-water ecosystems and conducting beaver control for the benefit of salmonids, and this dilemma is further complicated when the salmonids in question are a non-native species. We anticipate future beaver-salmonid research will lead to a greater understanding of this ecologically-complex relationship that may better inform managers when and where beaver control is necessary to achieve the desired management objectives. Understanding how wildlife populations respond to density-dependent (DD) and density- independent (DI) factors is critically important for wildlife management and research, as this knowledge can allow us to predict population responses to forcing mechanisms such as climate, predation, and exploitation. Recent advancements in statistical methods have allowed researchers to disentangle the relative influence each factor has on wildlife population dynamics, but this work is ongoing. Using a long-term dataset collected from 1975 to 2002, we sought to evaluate the relative influence DD and a suite of covariates (weather, harvest, habitat quality, and wolf [Canis lupus] predation) had on annual rates of change in the number of beaver (Castor canadensis) colonies among 15 populations in northern Minnesota, USA. We modeled changes in beaver colony densities using a discrete-time Gompertz model within a Bayesian inference framework, and compared model performance among three global models using Deviance Information Criterion (DIC) widely available information criterion (WAIC): a DI model without covariates; a DD model without covariates; and a DD model with covariates. Our results provide strong evidence for compensatory (negative) DD within beaver colony dynamics. We found no evidence that covariates related to harvest, wolf predation, or habitat quality significantly influenced beaver colony growth rates, but cold winters (lag-0), spring drought (lag-0), and fall drought conditions (lag-2) were correlated with greater colony growth rates. Despite strong evidence of the effect of environmental covariates on beaver colony dynamics, prediction of colony dynamics using these covariates showed only minimal improvements. We suggest the lack of improvement in prediction was the result of model over-fitting, indicating our significant covariate effects may not be biologically relevant. Our analysis demonstrates how reliance on information criterion values may lead to erroneous conclusions in time-series analyses, and using a hindcasting approach like the one we present here may help determine whether model results are biologically relevant or merely statistically significant. Our results highlight the importance of long-term monitoring programs for evaluating the efficacy of predictive ecological models. That beaver populations are primarily intrinsically regulated has important management implications depending on whether the objectives concern eradicating beavers from unwanted regions, mitigating conflicts, or facilitating rewilding or colonization efforts.
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    Vegetation Response to Adaptive Silviculture Treatment Aimed at Climate Change in Northern Minnesota, USA
    (2019-12) Muller, Jacob
    The Adaptive Silviculture for Climate Change (ASCC) project was developed to provide regionally-specific examples of on-the-ground adaptation approaches that address complex management challenges. The ASCC project includes three adaptation options (resistance, resilience, and transition) along with a no action treatment for comparison. The first replicated ASCC site (MN-ASCC) is located on the Cutfoot Experimental Forest (CEF) on the Chippewa National Forest in northern Minnesota, USA. Research efforts presented here focus on short- and long-term vegetation response of the adaptation options by comparing initial performance of planted seedlings in the transition treatment, examining effects of adaptive treatments on below-canopy microclimate, and assessing and comparing long-term performance of each treatment using the Forest Vegetation Simulator (FVS) model. To assess seedling performance, eight future climate-adapted tree species were planted following harvest in 2015. Four native species and four novel species to the CEF were monitored for three years (2015-2018). Results show seedling performance varied among the planted species, overstory conditions, and shrub/herbaceous densities. These findings indicate it may be reasonable for managers to consider novel species compositions to begin transitioning forests to future-climate adapted species compositions. To explore the relationship between overstory condition and below-canopy microclimate, 40 microclimate stations were installed across four overstory conditions ranging in density levels. Hemispherical photography was used to estimate overstory conditions while microclimate variables were sampled hourly over the entire 2017 growing season. Results from this study highlight the potential for silvicultural treatments to enhance microsite conditions for diverse future-adapted species compositions. Additionally, these findings suggest it may be advantageous to maintain lower stocking levels of red pine to help retain soil moisture and further enhance microsite conditions. Finally, FVS was used to assess whether the ASCC treatments attained long-term desired future conditions and to determine treatment success in terms of growth, productivity, and survival. These results highlight the relative success of the transition treatment, which had greater volume production and lower mortality than the other treatments. Overall, these findings further our understanding of important tree- and stand-level responses to adaptive silviculture treatment, and highlights important real-world implications for today’s natural resource manager.
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    Wildlife community data in black ash wetlands
    (2021-10-01) Grinde, Alexis R; agrinde@d.umn.edu; Grinde, Alexis R; NRRI Avian Ecology Research Lab
    Black ash wetlands cover approximately 1.2 million hectare of wetland forest in the western Great Lakes region, providing critical habitat for wildlife. The future of these wetlands is critically threatened by a variety of factors, including Emerald Ash Borer (Agrilus planipennis; EAB), which has been eliminating native populations of otherwise healthy ash throughout the Great Lakes Region since it was discovered in 2002. To quantify the potential impacts of tree mortality from EAB on wildlife communities, we measured seasonal bird, mammal, and amphibian diversity in black ash wetlands using a dual approach: 1) documenting bird and amphibian species across 27 mature reference black ash wetlands in northern Minnesota, USA and 2) assessing how bird, mammal, and amphibian communities respond to experimental manipulations of black ash forests that emulate mortality and management strategies related to the potential impact of EAB. A total of 85 wildlife species were recorded for the entire study including 57 bird species, 5 amphibian species, and 23 mammal species. Results from the reference sites show that hydrologic regime, percentage of ash canopy cover, and understory cover were important habitat characteristics for bird and amphibian communities. Results from the experimental sites show there may be short-term increases in species richness for mammal and bird communities associated with changes in forest structure due to ash mortality; however, anticipated changes resulting from EAB-caused mortality, particularly conversion of these sites to non-forested wetlands, will lead to significant shifts in bird and mammal community composition. Loss of ash may cause declines in forest-dependent species and increases in open-canopy and wetland-associated species. Additionally, while increased ponding extent and longer hydroperiods may be beneficial for some amphibian species, the loss of the forest canopy will result in an overall decrease in bird diversity and reduce forest connectivity for all species. Our results indicate the potential for significant large-scale impacts of black ash mortality on forest-associated wildlife. Management strategies that focus on establishing alternative trees species to maintain long-term forest cover and structural complexity in these wetlands will help maintain and conserve wildlife diversity.