Connections between vegetation and soil thermal dynamics are critical for estimating the vulnerability of permafrost to thaw with continued climate warming and vegetation changes. The interplay of complex biophysical processes results in a highly heterogeneous soil temperature distribution on small spatial scales. Moreover, the link between topsoil temperature and active layer thickness remains poorly constrained. Sixty-eight temperature loggers were installed at 1–3 cm depth to record the distribution of topsoil temperatures at the Trail Valley Creek study site in the northwestern Canadian Arctic. The measurements were distributed across six different vegetation types characteristic for this landscape. Two years of topsoil temperature data were analysed statistically to identify temporal and spatial characteristics and their relationship to vegetation, snow cover, and active layer thickness. The mean annual topsoil temperature varied between −3.7 and 0.1 ^∘C within 0.5 km². The observed variation can, to a large degree, be explained by variation in snow cover. Differences in snow depth are strongly related with vegetation type and show complex associations with late-summer thaw depth. While cold winter soil temperature is associated with deep active layers in the following summer for lichen and dwarf shrub tundra, we observed the opposite beneath tall shrubs and tussocks. In contrast to winter observations, summer topsoil temperature is similar below all vegetation types with an average summer topsoil temperature difference of less than 1 ^∘C. Moreover, there is no significant relationship between summer soil temperature or cumulative positive degree days and active layer thickness. Altogether, our results demonstrate the high spatial variability of topsoil temperature and active layer thickness even within specific vegetation types. Given that vegetation type defines the direction of the relationship between topsoil temperature and active layer thickness in winter and summer, estimates of permafrost vulnerability based on remote sensing or model results will need to incorporate complex local feedback mechanisms of vegetation change and permafrost thaw.

中文翻译：

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将苔原植被，雪，土壤温度和永久冻土联系起来

植被与土壤热力学之间的联系对于估算随着气候持续变暖和植被变化而造成的永久冻土融化的脆弱性至关重要。复杂的生物物理过程相互影响，导致在小空间尺度上高度异质的土壤温度分布。而且，表土温度和活性层厚度之间的联系仍然受到约束。在1-3厘米深度处安装了68个温度记录器，以记录加拿大西北部地区Trail Valley Creek研究现场的表土温度分布。测量值分布在该景观的六种不同植被类型特征上。对两年的表土温度数据进行了统计分析，以确定时空特征及其与植被，积雪和活动层厚度的关系。年平均表层土壤温度在− 0.5 km ²内为3.7和 ^0.1∘C。观察到的变化在很大程度上可以通过积雪的变化来解释。雪深的差异与植被类型密切相关，并且显示出与夏末融化深度的复杂关联。虽然冬季寒冷的土壤温度与次夏的苔藓和矮灌木苔原的深层活动层有关，但我们观察到高灌木和丛下面的情况相反。与冬季观察相反，在所有植被类型下，夏季表土的温度均相似，夏季表土的平均温差小于 ^1∘。C.此外，夏季土壤温度或累积正温度日数与活动层厚度之间没有显着关系。总之，我们的结果表明，即使在特定的植被类型中，表土温度和活性层厚度的空间变化也很大。考虑到植被类型定义了冬季和夏季表土温度与活动层厚度之间关系的方向，基于遥感或模型结果的多年冻土脆弱性估算将需要结合植被变化和多年冻土融化的复杂局部反馈机制。