Differences in mammal community response to highway construction across different levels of human land use

Worldwide, transportation agencies have been involved in road mitigation
efforts to reduce road mortality and promote connectivity of endangered
species. Baseline data on how mammals respond to highway construction,
however, is rarely collected in road mitigation and monitoring studies,
including in the United States. Our goal in this study was to assess
differences in the response of the mammal community to highway
construction along a gradient of human land use (HLU) from July 2019 to
November 2020 in southern Texas, United States. We compared the species
composition of the terrestrial mammal community at five sites along a
highway before and during highway construction and assessed diel activity
for seven species at different HLU levels between these two time periods.
We found that mammal community composition was lower during the
construction period at each HLU level. There were greater differences in
the composition of the mammal community in the pre-construction and
construction periods as HLU decreased. Community diversity was greatest in
areas with a low level of HLU, followed by areas of medium and high
levels, with more carnivores, large ungulates, and rodents at medium and
low HLU sites. For many species, diel activity patterns across all sites
during the construction period reflected activity patterns in areas of
higher HLU during the pre-construction period. Our study shows that
community composition and behavior (diel activity) are likely to change in
response to highway construction regardless of the degree of HLU. These
results may influence how scientists and transportation agencies consider
potential impacts on wildlife species during road construction and affect
their attempt to mitigate these impacts.

全球范围内，交通管理机构始终参与道路生态缓解工作，旨在降低野生动物道路致死率，同时提升濒危物种的栖息地连通性。然而，包括美国在内的诸多道路生态缓解与监测研究中，极少会收集哺乳动物对公路建设响应的基线数据。本研究于2019年7月至2020年11月期间，在美国德克萨斯州南部开展，旨在评估不同人类土地利用（Human Land Use, HLU）梯度下，哺乳动物群落对公路建设的响应差异。我们对比了某公路沿线5个监测点位在公路建设前与建设期间的陆生哺乳动物群落物种组成，并分析了两个时段内7个物种种群在不同HLU水平下的昼夜活动节律。研究结果显示，在各HLU梯度上，公路建设阶段的哺乳动物群落物种组成丰度均较建设前期有所下降。随着HLU水平降低，公路建设前后哺乳动物群落组成的差异愈发显著。群落多样性在低HLU水平区域最高，其次为中HLU与高HLU水平区域；中、低HLU点位的食肉目动物、大型有蹄类及啮齿类物种占比更高。对于多数物种而言，公路建设阶段所有监测点位的昼夜活动节律，与建设前期高HLU区域的活动节律特征一致。本研究表明，无论HLU梯度如何，公路建设均可能引发哺乳动物群落组成与行为（昼夜活动节律）的改变。本研究结果可为科学家与交通管理机构评估公路建设对野生动物的潜在影响提供参考，并助力其优化后续道路生态缓解措施的制定与实施。