MAMMALIAN HERBIVORY SLOWS THE GROWTH OF BROADLEAF SPECIES IN POST-FIRE, EARLY SUCCESSIONAL FORESTS IN INTERIOR ALASKA

Boreal forest vegetation is likely to change in response to warming and associated changes in disturbance regimes. Recently, high severity fires have caused a shift from pre-fire mature black spruce stands to early assemblages of broadleaf trees. However, interactions between plants and animals may modify the outcomes of early forest succession. Selective herbivory by mammalian herbivores can alter the relative dominance of forest canopy species and influence successional pathways. However, woody plants have evolved multiple strategies to maximize chances of survival and long-term fitness after herbivory. In this thesis, I explore the dynamics of moose-tree interactions and their consequences for early succession in boreal forests of interior Alaska. I assessed the interaction of moose browsing and fire severity on tree growth and canopy composition and found that moose slow the rate of trembling aspen growth, but only in severely burned areas. Black spruce showed no direct or indirect growth responses to moose browsing, indicating that moose browsing on aspen did not alter the initial trajectory to an aspen-dominated canopy within my study area. In lightly burned areas, moose may benefit from longer durations of forage availability and accelerate the development of a mixed spruce-aspen canopy. Alaskan paper birch is the other dominant broadleaf species colonizing early post-fire forests and I determined saplings’ ability to tolerate simulated summer leaf stripping by moose. I found decreases in woody growth and carbon-based defenses while individual leaf area increased in response to simulated leaf stripping. My results are consistent with the carbon-nutrient balance hypothesis suggesting that the loss of growing points during leaf stripping decreased competition for nutrients, which were then available for leaf regrowth. Birch saplings have the potential to compensate for herbivory, but resilience of individuals will depend on the intensity, season, and frequency of herbivory. I set up long-term exclosures to test if mammalian herbivores can alter patterns of canopy succession in early post-fire sites that ranged in broadleaf dominance. Removal of natural moose herbivory inside exclosures led to species-specific responses after two years. Alaskan paper birch (dominant broadleaf species) grew larger when safe from herbivores while the opposite was true for black spruce. However, impacts of natural moose browsing on the dominant birch were insufficient to eliminate the competitive hierarchies that supported birch dominance of the canopy and suppressed growth of black spruce in the understory. I conclude that even with the negative impacts of moose on broadleaf species growth, their tolerance to browse damage enables their persistence as the dominant canopy species after large and severe fires in the boreal forest of Alaska

Assessing the comparative risk of plant protection products to honey bees, non-target arthropods and non-Apis bees

Background: In the European Union the placing of pesticides on the market requires as a prerequisite that a risk assessment demonstrates low risks to human health and the environment, among which includes pollinators. Currently risks are evaluated for honey bees and for non-target arthropods (NTA) of cultivated ecosystems. The actual protection of pollinators other than the honey bees, as for example for non-Apis bees, in relation to these risk assessments has recently been questioned and requires further investigation. We present the findings from a comparison of Hazard Quotient (HQ) value calculations to assess the risk to honey bees, non-target arthropods and to non-Apis bees (with the application of an additional safety factor of 10). Calculations were based on publicly available ecotoxicological data. Results: The risk to NTA, honey bees and non-Apis bees, as depicted by HQ values, indicated a higher fail rate for NTA than for bees, but a similar pass / fail rate for non-Apis bees when compared to the NTA scheme. Outcome of the risk assessment for NTA using extended laboratory tests gave similar pass/fail rates compared to the screening step for honey bees. Conclusion: A screening step for non-Apis bees could be developed based on data available on honey bees and NTAs. Keywords: risk assessment, non-Apis bees, pollinators, pesticides, non-target arthropod

Exposure of honey bees and other pollinating species to pesticides

Background: When considering the risk to bees a thorough understanding of the relevant routes of exposure and the magnitude of exposure is necessary.Results: Bees forage on plants and in particular flowers to obtain food for themselves and for provisioning their young. Foliar applications during flowering will present the most extreme acute exposure situation. Bees can be exposed to direct spray and also to contaminated pollen and nectar taken back to the colony. Spray applications before flowering may lead to exposure in pollen and nectar if the substance has systemic properties and is persistent. For soil/seed treatments exposure may occur in for systemic products due to translocation from the seed or soil to the upper parts of the plant (e.g. nectar and pollen). Other possible routes for soil/seed treatments include dust-off at sowing and guttation water. Conclusion: Risk assessment requires that relevant routes of exposure for worker bees, hive bees and young should be considered in the risk assessment for both foliar applied and seed/soil treatment pesticides. The availability of exposure models would assist in the development of honey bee and pollinator risk assessment schemes.Keywords: honey bee, pesticide, risk assessment, exposur

Driver Knowledge, Beliefs, and Attitudes About Deer–Vehicle Collisions in Southern Michigan

Deer–vehicle collisions (DVCs) are one of the most frequent and costly human– wildlife conflict throughout the range of white-tailed deer (Odocoileus virginianus). We conducted a self-administered, mail-back survey of Michigan drivers to determine: (1) driver attitudes and knowledge about DVCs; (2) reporting rates of DVCs; and (3) effects of being in a DVC on attitudes toward desired deer population levels. From a sample of 3,600 randomly selected licensed drivers \u3e18 years of age in southeast Michigan, we obtained 1,653 completed questionnaires (48% response rate). Although 18% of respondents reported experiencing \u3e1 DVC within 5 years of the survey and 81% of them perceived DVCs to be a serious problem, drivers stated a willingness to make only modest changes in their driving behavior to minimize risk of a DVC. Most respondents (79%) believed DVCs were unavoidable. Only 46% of drivers involved in \u3e1 DVCs indicated that they reported it to police, and 52% reported the DVC to their insurance company. Drivers involved in DVCs were more likely than other drivers to be male, drive more, be more knowledgeable about DVCs, and be more likely to desire a decrease in the deer population. If reporting rates revealed in this study are an indication of rates elsewhere, DVCs are a much greater hazard than previously estimated

Towards comprehensive annotation of Drosophila melanogaster enzymes in FlyBase.

The catalytic activities of enzymes can be described using Gene Ontology (GO) terms and Enzyme Commission (EC) numbers. These annotations are available from numerous biological databases and are routinely accessed by researchers and bioinformaticians to direct their work. However, enzyme data may not be congruent between different resources, while the origin, quality and genomic coverage of these data within any one resource are often unclear. GO/EC annotations are assigned either manually by expert curators or inferred computationally, and there is potential for errors in both types of annotation. If such errors remain unchecked, false positive annotations may be propagated across multiple resources, significantly degrading the quality and usefulness of these data. Similarly, the absence of annotations (false negatives) from any one resource can lead to incorrect inferences or conclusions. We are systematically reviewing and enhancing the functional annotation of the enzymes of Drosophila melanogaster, focusing on improvements within the FlyBase (www.flybase.org) database. We have reviewed four major enzyme groups to date: oxidoreductases, lyases, isomerases and ligases. Herein, we describe our review workflow, the improvement in the quality and coverage of enzyme annotations within FlyBase and the wider impact of our work on other related databases