Evaluating Karner Blue Butterfly (Lycaeides Melissa Samuelis Nabokov) Habitat Selection in the State of Wisconsin, USA

The federally endangered Karner blue butterfly (Lycaeides melissa samuelis Nabokov) persists in rare oak/pine grassland communities spanning across the Great Lakes region, relying on host plant wild blue lupine (Lupinus perennis). Conservation efforts since 1992 have led to the development of several programs that restore and monitor habitat. This study aims to evaluate Karner blue habitat selection in the state of Wisconsin and develop high-resolution tools for use in conservation efforts. Spatial predictive models developed during this study accurately predicted potential habitat across state properties based on soils and canopy cover, and identified ~51-100% of Karner blue occurrences based on lupine and shrub/tree cover, and focal nectar plant abundance. When evaluated relative to American bison (Bison bison), Karner blues and lupine were more likely to occur in areas of low disturbance, but aggregated where bison were recently present in areas of moderate/high disturbance. Lupine C:N ratio increased relative to cover of shrubs/trees and focal nectar plant abundance and decreased relative to cover of groundlitter. Karner blue density increased with lupine C:N ratio, decreased with nitrogen content, and was not related to phenolic levels. We strongly suggest that areas of different soil textures must be managed differently and that maintenance techniques should generate a mix of shrubs/tree cover (10-45%), groundlitter cover (~10-40%), >5% cover of lupine, and establish an abundance of focal nectar plants. This study provides unique tools for use in conservation and should aid in focusing management efforts and recovery of this species.

Will Whole-Tree Harvest of Jack Pine (Pinus banksiana) deplete soil nutrients in low-productivity sand soils?

In 2009 and 2010 a study was conducted on the Hiawatha National Forest (HNF) to determine if whole-tree harvest (WTH) of jack pine would deplete the soil nutrients in the very coarse-textured Rubicon soil. WTH is restricted on Rubicon sand in order to preserve the soil fertility, but the increasing construction of biomass-fueled power plants is expected to increase the demand for forest biomass. The specific objectives of this study were to estimate biomass and nutrient content of above- and below-ground tree components in mature jack pine (Pinus banksiana) stands growing on a coarse-textured, low-productivity soil, determine pools of total C and N and exchangeable soil cations in Rubicon sand, and to compare the possible impacts of conventional stem-only harvest (CH) and WTH on soil nutrient pools and the implications for productivity of subsequent rotations. Four even-aged jack pine stands on Rubicon soil were studied. Allometric equations were used to estimate above-ground biomass and nutrients, and soil samples from each stand were taken for physical and chemical analysis. Results indicate that WTH will result in cation deficits in all stands, with exceptionally large Ca deficits occurring in two stands. Where a deficit does not occur, the cation surplus is small and, chemical weathering and atmospheric deposition is not anticipated to replace the removed cations. CH will result in a surplus of cations, and will likely not result in productivity declines during the first rotation. However even under CH, the surplus is small, and chemical weathering and atmospheric deposition will not supply enough cations for the second rotation.

Vegetation and hydrologic influences on carbon and nitrogen in subsurface water of a forested riparian wetland

Vegetation communities affect carbon and nitrogen dynamics in the subsurface water of mineral wetlands through the quality of their litter, their uptake of nutrients, root exudation and their effects on redox potential. However, vegetation influence on subsurface nutrient dynamics is often overshadowed by the influences of hydrology, soils and geology on nutrient dynamics. The effects of vegetation communities on carbon and nitrogen dynamics are important to consider when managing land that may change vegetation type or quantity so that wetland ecosystem functions can be retained. This study was established to determine the magnitude of the influences and interaction of vegetation cover and hydrology, in the form of water table fluctuations, on carbon and nitrogen dynamics in a northern forested riparian wetland. Dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), nitrate (NO3-) and ammonium (NH4+) concentrations were collected from a piezometer network in four different vegetation communities and were found to show complex responses to vegetation cover and water table fluctuations. Dissolved organic carbon, DIC, NO3- and NH4+ concentrations were influenced by forest vegetation cover. Both NO3- and NH4+ were also influenced by water table fluctuations. However, for DOC and NH4+ concentrations there appeared to be more complex interactions than were measured by this study. The results of canonical correspondence analysis (CCA) and analysis of variance (ANOVA) did not correspond in relationship to the significance of vegetation communities. Dissolved inorganic carbon was influenced by an interaction between vegetation cover and water table fluctuations. More hydrological information is needed to make stronger conclusions about the relationship between vegetation and hydrology in controlling carbon and nitrogen dynamics in a forested riparian wetland.

DENITRIFICATION IN SOILS: FROM GENES TO ENVIRONMENTAL OUTCOMES

Denitrification is an important process of global nitrogen cycle as it removes reactive nitrogen from the biosphere, and acts as the primary source of nitrous oxide (N2O). This thesis seeks to gain better understanding of the biogeochemistry of denitrification by investigating the process from four different aspects: genetic basis, enzymatic kinetics, environmental interactions, and environmental consequences. Laboratory and field experiments were combined with modeling efforts to unravel the complexity of denitrification process under microbiological and environmental controls. Dynamics of denitrification products observed in laboratory experiments revealed an important role of constitutive denitrification enzymes, whose presence were further confirmed with quantitative analysis of functional genes encoding nitrite reductase and nitrous oxide reductase. A metabolic model of denitrification developed with explicit denitrification enzyme kinetics and representation of constitutive enzymes successfully reproduced the dynamics of N2O and N2 accumulation observed in the incubation experiments, revealing important regulatory effect of denitrification enzyme kinetics on the accumulation of denitrification products. Field studies demonstrated complex interaction of belowground N2O production, consumption and transport, resulting in two pulse pattern in the surface flux. Coupled soil gas diffusion/denitrification model showed great potential in simulating the dynamics of N2O below ground, with explicit representation of the activity of constitutive denitrification enzymes. A complete survey of environmental variables showed distinct regulation regimes on the denitrification activity from constitutive enzymes and new synthesized enzymes. Uncertainties in N2O estimation with current biogeochemical models may be reduced as accurate simulation of the dynamics of N2O in soil and surface fluxes is possible with a coupled diffusion/denitrification model that includes explicit representation of denitrification enzyme kinetics. In conclusion, denitrification is a complex ecological function regulated at cellular level. To assess the environmental consequences of denitrification and develop useful tools to mitigate N2O emissions require a comprehensive understanding of the regulatory network of denitrification with respect to microbial physiology and environmental interactions.

RESPONSE OF ECTOMYCORRHIZAL FUNGI TO INORGANIC AND ORGANIC FORMS OF NITROGEN AND PHOSPHORUS

The nutrient uptake response of ectomycorrhizal fungi (ECM) to different nutrient substrates is a driving force in ecosystem nutrient cycling. We hypothesized that taxa from low nitrogen (N) soils would be more likely to use organic N compared to taxa from high N soils, and that taxa from high N would be more likely to use organic phosphorus (P) sources when compared to the ECM dominant in low N soils. This study focuses on the growth response of ECM species collected over a N gradient to different forms of N and P nutrient substrates and whether ECM growth in a particular nutrient source can be related to how the ECM fungi have responded to elevated N in the field. This study found a mixed ECM response to organic and inorganic N and P treatments. High affinity N taxa expected to respond positively to inorganic N produced the phosphatase enzyme to take up organic phosphorus, but not all low affinity N taxa expected to negatively respond to organic P produced the protease enzyme to take up organic N. Interspecific variability was displayed by some high and low affinity N taxa responded and ECM intraspecific variability in response to N and P treatments was also noted. Future analysis of may show more evident ECM response patterns to inorganic and organic forms of N and P.