Drasher Caitlin E, Slesar Chris, Hawkins-Hilke Jens, Gingras Glenn, Marangelo Paul, Landau Vincent, Hall Kimberly R, Pearman-Gillman Schuyler B, Murdoch James D
Wildlife and Fisheries Biology Program, Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, Vermont, United States of America.
Vermont Agency of Transportation, Barre, Vermont, United States of America.
PLoS One. 2025 Sep 4;20(9):e0331493. doi: 10.1371/journal.pone.0331493. eCollection 2025.
Landscape connectivity is often negatively impacted by road networks that fragment habitat and result in genetic and demographic consequences for wildlife. Existing roadway structures like bridges, culverts, and underpasses can facilitate connectivity and reduce the barrier effect of roads by providing less risky areas for animals to cross. Estimating areas of high wildlife movement near roads is beneficial for prioritizing transportation investments for wildlife. We used an omnidirectional circuit theory approach to model the movements of eight terrestrial mammal species across the state of Vermont, a forested region central to the globally important Northern Appalachian ecoregion. We combined expert-derived landscape resistance surfaces with wildlife occurrence data to develop species-specific connectivity models at statewide (23,873 km2, 30 m resolution) and roadway structure (100 m radius around 5,912 structures, 0.5 m resolution) scales. The flow of animal movement across the landscape, depicted as electrical current density, was highest for forest-obligate species along the forested, mid-elevation foothills of the Green Mountains in central Vermont and lowest in the agricultural Champlain Valley; however, for more urban- and agriculture-adapted species, flow was highest in developed areas and lower elevation valleys. Average current density was highest for black bear (Ursus americanus), and lowest for striped skunk (Mephitis mephitis) at the statewide scale and highest for raccoon (Procyon lotor) and lowest for moose (Alces alces) at the finer structure scale. Results at both scales revealed different patterns of expected animal movement that reflect the relative extent of connectivity. We then scored connectivity for each structure across all species by combining both scales using four different methods to capture a range of management interests. Rankings varied greatly depending on the method used, highlighting the need to clearly articulate objectives when scoring structures or other features in a landscape. Resistance, occupancy, and current maps also indicated the broad importance of intact forest for connectivity and may be particularly important for identifying priority regions for protection under Vermont's Community Resilience and Biodiversity Protection Act that mandates protecting 50% of the state by 2050.
景观连通性常常受到道路网络的负面影响，道路网络会分割栖息地，并给野生动物带来遗传和种群统计学方面的后果。诸如桥梁、涵洞和地下通道等现有的道路结构可以通过为动物提供风险较小的区域来促进连通性，并降低道路的屏障效应。估算道路附近野生动物高活动区域，有利于确定野生动物运输投资的优先次序。我们采用全向电路理论方法，对佛蒙特州（位于全球重要的北阿巴拉契亚生态区中心的一个森林地区）的8种陆生哺乳动物的活动进行建模。我们将专家得出的景观阻力面与野生动物出现数据相结合，在全州范围（23,873平方公里，30米分辨率）和道路结构范围（5,912个结构周围半径100米，0.5米分辨率）建立特定物种的连通性模型。动物在景观中的活动流，以电流密度表示，在佛蒙特州中部格林山脉森林覆盖的中海拔山麓地带，对依赖森林的物种来说最高，在尚普兰湖农业山谷最低；然而，对于更适应城市和农业环境的物种，活动流在发达地区和低海拔山谷最高。在全州范围，黑熊（美洲黑熊）的平均电流密度最高，条纹臭鼬（北美臭鼬）最低；在更精细的结构范围，浣熊（北美浣熊）最高，驼鹿（驼鹿）最低。两个尺度的结果都揭示了预期动物活动的不同模式，反映了连通性的相对程度。然后，我们通过四种不同方法结合两个尺度，对所有物种的每个结构的连通性进行评分，以涵盖一系列管理关注点。排名因所用方法的不同而有很大差异，这凸显了在对景观中的结构或其他特征进行评分时明确阐述目标的必要性。阻力、占用率和电流图还表明了完整森林对连通性的广泛重要性，这对于根据佛蒙特州的《社区复原力和生物多样性保护法》确定保护优先区域可能尤为重要，该法案要求到2050年保护该州50%的区域。
