Dissertation

Songbird Response to Forest Disturbance Due to Unconventional Shale Gas Development in the Marcellus-Utica Region: A Multi-Scale Analysis

Farwell, Laura S

2018

Overview

In this study, I evaluated impacts of unconventional shale gas development, or the combined use of horizontal drilling and hydraulic fracturing (i.e., fracking), on forest land cover and breeding songbirds in the Marcellus-Utica shale region. Since 2005, extraction of natural gas from the Marcellus-Utica shale has increased exponentially in the central Appalachians, an area of high conservation value for global biodiversity. Although there has been an increase in research on the effects of shale gas development in the region, the industry is still relatively new in the eastern U.S. and much is still unknown about biological and environmental impacts. In Chapter 1, I summarize potential effects of unconventional shale gas development on regional forests, and review the literature on songbird responses to forest loss and fragmentation. I also outline the overall research objectives of this dissertation and provide a summary of chapter topics. In Chapter 2, I evaluated the effects of shale gas development on a heavily forested, long-term study site in northern West Virginia, from 2008–2015. Construction of gas well pads and linear infrastructure contributed to an overall 4.5% loss in forest cover at the site, a 12.4% loss in core forest, and a 51.7% increase in forest edge density. I evaluated the relationship between land-cover metrics and species richness within three avian guilds: forest-interior, early-successional, and synanthropic, in addition to abundances of 21 focal species. Land-cover impacts were evaluated at two spatial extents: a point-level within 100-m and 500-m buffers of each avian survey station, and a landscape-level across the study area (4,326 ha). Although I observed variability in species-specific responses, I found distinct trends in long-term response among the three avian guilds. Forest-interior species richness declined at all points across the site and at points impacted within 100 m by shale gas but did not change at unimpacted points. Early-successional and synanthropic species richness increased at all points and at impacted points but did not change at unimpacted points. In Chapter 3, I focused on spatial responses of focal songbird species to distance from shale gas development, at the same long-term study site in northern West Virginia (2008–2017). I found that more than half of the focal species evaluated showed sensitivity to distance from shale gas infrastructure. Several forest interior species occurred in higher abundances with increasing distance from shale gas, while a few forest interior gap specialists increased in abundance closer to shale gas. Early successional and synanthropic species generally occurred in higher abundances closer to shale gas. Interpolated distribution maps for four focal species helped visualize patterns of spatial response to shale gas development, over time. In Chapter 4, I conducted a region-wide assessment of impacts of Marcellus-Utica shale gas development on forests and breeding songbirds in the central Appalachian region. I evaluated land cover and bird count data from 190 forested sites across the Marcellus-Utica region: 120 sites affected by shale gas development and 70 sites affected only by human development unrelated to shale gas. First, I quantified the footprint of shale gas infrastructure in forested landscapes and found that shale gas generally occupied a relatively small footprint on the landscape (x? = 2.7%), and that linear shale gas infrastructure accounted for greater forest loss and fragmentation than well pad development region. I then compared bird community assemblages at sites with and without shale gas development and found they did not differ, suggesting that at a broad scale, bird communities generally responded similarly to shale gas development and other types of human-caused forest disturbance. However, finer-resolution analyses of bird counts across gradients of forest cover and human development revealed some distinct patterns of songbird response relative to shale gas development: I observed lower species richness and abundance among forest interior birds relative to shale gas metrics, while early successional and synanthropic birds showed higher richness and abundance relative to shale gas development. Lastly, in Chapter 5, I evaluated potential region-wide threshold responses in species abundance to distance from human development and percent forest/core forest cover, across the Marcellus-Utica shale region. My results supported the occurrence of some threshold avian responses to distance from shale gas development, and narrower threshold responses to the proportion of forest cover and core forest cover in landscapes altered by shale gas development. These findings are consistent with other localized studies from the region, documenting decreasing abundance and diversity of forest interior birds and increasing numbers and diversity of disturbance-dependent and human adapted species, in landscapes altered by shale gas development. (Abstract shortened by ProQuest.)

• Publisher: ProQuest Dissertations & Theses
• Subject: Forestry / Wildlife Conservation / Wildlife Management
• ISBN: 9780438322271, 0438322274