Slovikosky Sandy A, Merrick Melissa J, Morandini Marina, Koprowski John L
School of Natural Resources and the Environment, University of Arizona, 1064 E. Lowell Street, Tucson, AZ 85721, United States.
Department of Biology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, United Kingdom.
J Mammal. 2023 Dec 24;105(1):157-167. doi: 10.1093/jmammal/gyad117. eCollection 2024 Feb.
Disturbance events are increasing at a global scale, with cascading impacts to ecosystems and residents therein that include fragmentation and altered vegetation structure and composition. Such changes may disproportionately impact small mammal movements, risk perception, and community dynamics as smaller species perceive such changes at finer spatial scales. We examined movement response to burn severity, vegetation structure, and composition in Mexican woodrats (), a common but understudied small mammal species. The study was conducted on Mt. Graham in southeastern Arizona, United States, following a fire that burned over 19,400 ha. We measured path tortuosity of woodrats translocated over patches of different burn severity. Tortuosity can indicate microhabitat selection, foraging behavior, and perceived predation risk-features affecting population-level processes that changes in community composition alone cannot fully demonstrate. We captured woodrats, released them 50 m away from their midden, and used fluorescent powder to track woodrat movement paths through areas of low-severe burn severity. We analyzed features of the resulting powder trails including straightness, average step length, fractal dimension, and squared displacement. We also compared used versus expected vegetation structure and composition along movement paths across burn severities. Analyses indicated shorter step length with increased bare ground, as well as higher squared displacement in areas with more logs. Vegetation analyses likewise showed that logs were heavily used in low-burned areas, whereas dense vegetation was avoided in highly burned areas. Burn severity alone did not have a direct effect on movement parameters, rather its influence on vegetative composition and structure appears to be most important. Selection for logs and avoidance of dense vegetation may be attributed to auditory concealment and ease of travel. With projected increases in wildfire extent and severity, this work represents an understudied approach to understanding these disturbances and their effects on ecological communities.
干扰事件在全球范围内不断增加，对生态系统及其居民产生连锁影响，包括破碎化以及植被结构和组成的改变。由于较小的物种在更精细的空间尺度上感知到这些变化，此类变化可能会对小型哺乳动物的活动、风险感知和群落动态产生不成比例的影响。我们研究了墨西哥林鼠（）对火烧强度、植被结构和组成的活动反应，这是一种常见但研究不足的小型哺乳动物。该研究在美国亚利桑那州东南部的格雷厄姆山进行，此前一场火灾烧毁了超过19400公顷的土地。我们测量了在不同火烧强度斑块上迁移的林鼠的路径曲折度。曲折度可以表明微生境选择、觅食行为以及感知到的捕食风险，这些特征会影响种群水平的过程，而仅群落组成的变化无法完全体现这些过程。我们捕获林鼠，将它们从其 midden 释放50米远，并使用荧光粉追踪林鼠在低强度火烧区域的活动路径。我们分析了由此产生的粉末痕迹的特征，包括直线度、平均步长、分形维数和平方位移。我们还比较了不同火烧强度下沿活动路径使用的植被结构和组成与预期的植被结构和组成。分析表明，随着裸地增加步长变短，在有更多原木的区域平方位移更高。植被分析同样表明，在低火烧区域原木被大量利用，而在高火烧区域则避免选择茂密植被。仅火烧强度对活动参数没有直接影响，相反，其对植被组成和结构的影响似乎最为重要。对原木的选择和对茂密植被的回避可能归因于听觉隐蔽和便于行走。随着野火范围和强度预计的增加，这项工作代表了一种研究不足的方法来理解这些干扰及其对生态群落的影响。
