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Dissertation/Thesis Abstract

Conservation Strategies that Address Habitat Loss and Fragmentation: Implications for Forest Cover Change and Wildlife Behavior
by Collins, Amy C., Ph.D., University of California, Davis, 2020, 139; 28149138
Abstract (Summary)

Habitat loss and fragmentation is currently the primary driver of biodiversity decline. Community forest management and wildlife crossing structures are two common conservation strategies applied to mitigate habitat loss and fragmentation. Community forest management is an approach that enables local communities to participate in forest management in order to reduce deforestation, and crossing structures are intended to mitigate the negative impacts of roads in fragmenting the landscape. To implement efficient design, their effectiveness needs to be examined using rigorous and appropriate methods. Herein, I assess the efficacy of each in the context of counterfactual assessments and baseline conditions. Using Pemba Island, Tanzania, as a case study, I monitor Community forest management, and use unprotected areas as the baseline. For wildlife crossing structures I examine structures along California highways, and use adjacent wildland areas absent of roads as the baseline. I employ methods such as remote sensing and hierarchical modeling to decipher forest cover change, wildlife movement, and behavioral responses within a fragmented habitat. I focus on particular anthropogenic stressors that may contribute to the efficacy of Community forest management and wildlife crossing structures, such as human population density, and light and noise pollution. The results offer solutions to the broader conservation community in how to evaluate the conservation tools we are currently utilizing. Furthermore, results guide the decision-making process for wildlife managers, practitioners, and agencies specific to these case studies and future conservation projects.

In my first chapter, I evaluate the Reduced Emissions in Deforestation and Degradation (REDD+) program, that uses payments for ecosystem services as incentives to communities managing and protecting forests. Given the relatively recent addition of REDD+ to the conservation toolkit, evaluation of outcomes from ongoing REDD+ projects is important. I examined whether the REDD+ program on Pemba, Tanzania, impacted forest cover change between 2001 – 2018. I controlled for confounding variables and the non-random selection of REDD+ areas by using a statistical matching procedure. The Pemba REDD+ program had no discernible effect on forest cover change during the eight years after initiation. Likewise, I did not detect an effect of environmental or sociological covariates on forest cover. However, REDD+ areas that did better than predicted consisted of small islands accessible only by boat. My findings suggest reducing deforestation through REDD+ is not certain, yet patterns of success at the local level must be recognized, and affordable monitoring should continue as replanting efforts take time to manifest. In addition, examining forest outcomes of REDD+ using high-quality data and appropriate statistical methods is necessary.

In my second and third chapters, I evaluate crossing structures that provide a safe route for wildlife to navigate across roads. The efficacy of wildlife crossing structures might be affected by the exposure of animals to increased noise and artificial light at night produced by vehicles. Therefore, I tested two hypotheses as to how wildlife perceives noise and light, 1) as a risk, contributing to a ‘Landscape of Fear’, or 2) as a refuge, or ‘Human Shield’. Wildlife can respond to fearful stimuli in four ways; spatial avoidance, temporal avoidance, increased anti-predator behavior and altered group sizes. In chapter 2, I examine alterations to spatial and temporal patterns in response to traffic noise and light pollution. I examined species richness (spatial response) and visitation rates (spatial response) of mule deer (prey), bobcats (predator) and coyotes (predator), as well as increased nocturnality (temporal response) in mule deer, bobcats, and coyotes at 26 crossing structures across California, USA, using camera traps. At higher levels of noise pollution, I found that species richness declined, mule deer and bobcat visitations declined, and mule deer nocturnality increased. In response to light pollution, I observed spatial avoidance by bobcats and coyotes and greater nocturnality for all three species. These results suggest that anthropogenic noise and light disturbance contribute to a Landscape of Fear across different trophic levels. However, species richness and deer visitations increased at high levels of light pollution, suggesting a Human Shield of light. These findings indicate wildlife are avoiding anthropogenic noise and light pollution via altering spatiotemporal patterns, and that a Landscape of Fear and Human Shield are non-mutually exclusive mechanisms used to lower predation risk. Species-level differences are likely attributed to trophic level and sensory systems. Using these results, I make recommendations for transportation sectors to better equip crossing structures with appropriate mitigation features.

In chapter 3, I examine the third and fourth response to fearful stimuli - altered anti-predator behavior and group sizes, and incorporate a multi-scale framework to identify differences in fear responses across spatiotemporal scales. Anthropogenic noise pollution is pervasive across the landscape and can be present at three temporal scales; instantaneous, (occurring sporadically over the shortest time scales e.g. milliseconds), acute (more persistent than instantaneous e.g. minutes), and chronic (weeks, years). Instantaneous noise could induce a startle response, whereas acute and chronic noise could alter anti-predator behavior such as vigilance and group size. We examined whether these three levels of anthropogenic noise pollution invoke a Landscape of Fear, ‘habituation’, or Human Shield response in mule deer (Odocoileus hemionus) and coyotes (Canis latrans) at highway crossing structures. We placed six camera traps at crossing structure entrances for a period of ~ two months across California to monitor decision-making (flight away from crossing structure or entry into crossing structure) and anti-predator behavior (vigilance, running, foraging, group size). Mule deer and coyotes demonstrated a Landscape of Fear response to instantaneous (2 seconds of noise) and chronic noise (1 week). For acute noise (~20 seconds), mule deer responded positively, most likely using crossing structures as a Human Shield, and coyotes demonstrated no alteration in response, thus likely habituating to localized noise. Our results are the first to demonstrate variations in fear response to anthropogenic noise disturbance across spatiotemporal scales. This dynamic response to fear could alter natural predator-prey interactions and scale up to ecosystem-level consequences such as trophic cascades.

Indexing (document details)
Advisor: Van Vuren, Dirk H.
Commitee: Post, Eric, Patricelli, Gail L.
School: University of California, Davis
Department: Ecology
School Location: United States -- California
Source: DAI-B 82/8(E), Dissertation Abstracts International
Subjects: Conservation biology, Wildlife Conservation, Behavioral Sciences, Remote sensing
Keywords: Community forest management, Fear ecology, Habitat loss, Road ecology, Wildlife crossing structures
Publication Number: 28149138
ISBN: 9798582531500
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