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University of Nevada, Las Vegas (2020)

Effects of Wildfire on Plant and Insect Pollinator Communities in the Mojave Desert

Nha Trang Vivian Sam

Titre : Effects of Wildfire on Plant and Insect Pollinator Communities in the Mojave Desert

Auteur : Nha Trang Vivian Sam

Université de soutenance : University of Nevada, Las Vegas

Grade : Master of Science – Biological Sciences 2020

Résumé
The changing fire regime of landscapes across the Mojave Desert has prompted considerable research on its effects on plant community recovery, but it has not been widely studied what effects wildfire may have on native pollinators and the vital ecosystem services they provide. Ecological changes from increased wildfire severity from invasive exotic annual grasses will likely continue influencing pollinator habitats and floral resources. Understanding the effects that wildfires have on pollinators is valuable to make decisions as to whether active management and restoration activities are required to conserve ecologically vital pollinator functions. The intention of this thesis was to examine the effects of wildfire on insect pollinator communities and whether insect pollinator communities may be associated with different vegetative community structures in burned and unburned areas.This thesis assessed plant and pollinator community differences between burned and unburned areas on three fires that occurred in 2005 in and around Red Rock National Conservation Area in Clark County, Nevada of the eastern Mojave Desert. The study was conducted through pan trapping, aerial netting, and floral visitor observations that took place in 2019-2020 and yielded over 4,600 individual insect pollinators within 62 taxa. Effects such as burn status and various plant community characteristics on pollinator abundance and richness after 14-15 years was evaluated. No significant differences occurred between burn status on general plant community variables including plant cover and richness. Burn status did not have a significant effect on overall richness and abundance of the pollinator communities of interest. However, burn status differences within the orders of Coleoptera, Hymenoptera, and Lepidoptera appear to be contingent on both sampling season and year. Burned sites had higher pollinator density in fall 2019, though this pattern did not occur in either of the spring seasons. Spring 2019 burned areas showed higher Hymenoptera density, while spring 2020 burned areas showed higher Lepidoptera density. Mixed model analyses of variance show associations of fire sites and various pollinator taxa and plant species. Considering that results of this study are varied, a main conclusion is that pollinators are resilient to wildfire and have appeared to recover to unburned pollinator community levels more fully than vegetation at 14 and 15 years since disturbance. Although these results do support hypotheses in the literature that predict insect pollinator groups to be marginally affected by wildfire, interpretations cannot be made on specific individual pollinator species or on how pollinators may respond immediately after wildfire occurs. Information from this research provides a basis for future studies on Mojave Desert wildfire and pollinator communities. These findings add to the broader understanding of Mojave Desert wildfire effects on pollinators and can help inform the management and restoration of pollinators and their habitats in arid lands.

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Page publiée le 13 décembre 2021