Fragnièere, Yann Morelon, Stéphanie Müller, Alain Kozlowski, Gregor 2026 Climatic microrefugia allow some forest tree species to persist outside their main distribution range by locally decoupling site conditions from the regional climate. At its western, oceanic range margin in the Swiss Prealps, the Swiss stone pine (Pinus cembra L.) occurs on large boulders embedded within subalpine forests dominated by Norway spruce [Picea abies (L.) H. Karst.]. We hypothesised that these landforms generate a continental-like microclimate enabling P. cembra persistence under otherwise sub-oceanic conditions, and we aimed to quantify this phenomenon. Using high-resolution data loggers, we measured air and soil temperature, thermal amplitudes, and soil moisture on the summits and at the bases of ten limestone boulders over a two-year period. Linear mixed-effects models revealed a pronounced microclimatic decoupling between positions. Boulder summits were consistently warmer and drier during the growing season. In contrast, during winter, summits were significantly colder, while boulder bases remained thermally stable due to persistent snow insulation. The strongest microclimatic divergence occurred in spring, when temperatures at the bases remained stable near 0 °C, whereas summit temperatures were markedly warmer and more variable. This continental-like microclimate likely promotes P. cembra persistence. Our results highlight the importance of topographic heterogeneity for maintaining marginal tree populations. application/pdf https://folia.unifr.ch/global/documents/335171 https://folia.unifr.ch/documents/335171/files/fragnireetal.2026pinuscembrajfs_0.pdf eng https://doi.org/10.17221/8/2026-JFS info:eu-repo/semantics/altIdentifier/doi/10.17221/8/2026-JFS info:eu-repo/semantics/openAccess CC BY Journal of Forest Science . - Czech Academy of Agricultural Sciences (CAAS). - 2026, vol. 72, no. 2, p. 82-92 Climatic microrefugia Microclimate measurements Relict species Subalpine forests Swiss stone pine Thermal decoupling Topographic heterogeneity Boulders as microrefugia: Quantifying a continental-like microclimate supporting Pinus cembra at its oceanic range margin http://purl.org/coar/resource_type/c_6501