Data for: Red foxes enhance long-term tree growth near the Arctic treeline

Recent climate warming is expected to increase tree growth and productivity, substantially altering ecological function and boundaries in northern ecosystems. Temperature and precipitation largely determine the range and growth of trees in any biome, yet variations in microsite conditions can also influence tree growth on a finer scale. By altering essential resources and habitat conditions, terrestrial organisms could modify Subarctic tree growth. Red foxes (Vulpes vulpes) are found in most terrestrial ecosystems and are considered ecosystem engineers by enriching soil nutrients and plant composition through denning. Added soil nutrients from prey remains, feces, and urine could benefit tree growth in Subarctic regions by alleviating soil nutrient limitations. We examined growth in white spruce (Picea glauca) trees growing on eight red fox dens and paired control sites near Churchill, Manitoba, Canada, at the Arctic treeline. Radial growth was 55% higher for trees on dens than on control sites between 1897 and 2017, despite similarities in tree ages, densities, and regional climate across all sites. By promoting tree growth near the treeline, red foxes may influence the position of the Arctic treeline. Although the impacts on tree growth largely depend on the spatial distribution of dens and predator activity in the boreal forest, predators can create distinct microhabitats across the landscape via ecosystem engineering processes, leading to increased vegetation productivity, persisting over many decades.

近期气候变暖预计将促进树木生长与生产力，显著改变北方生态系统的生态功能与生态边界。温度与降水在各类生物群系中主导了树木的分布与生长，但微生境条件的差异也会在更精细的尺度上影响树木生长。陆地生物可通过改变关键资源与栖息地条件，进而调控亚北极地区的树木生长。赤狐（Vulpes vulpes）广泛分布于多数陆地生态系统，因其通过穴居活动提升土壤养分与植物群落组成，被视为生态系统工程师。其通过猎物遗骸、粪便与尿液输入的土壤养分，可通过缓解亚北极地区的土壤养分限制，助力树木生长。本研究针对加拿大曼尼托巴省丘吉尔市附近北极林线区域的8处赤狐巢穴及配对对照样地，对白云杉（Picea glauca）的生长情况展开了调查。1897年至2017年间，尽管所有样地的树木树龄、密度与区域气候均无显著差异，但巢穴样地内树木的径向生长较对照样地高出55%。通过促进林线附近的树木生长，赤狐可能会对北极林线的位置产生影响。尽管其对树木生长的影响在很大程度上取决于巢穴的空间分布与食肉动物在北方针叶林内的活动，但食肉动物可通过生态系统工程过程在景观中形成独特微生境，进而提升植被生产力，且该效应可延续数十年之久。