Deadwood-dominated forests buffer microclimate in exposed mountain areas

Microclimatic buffering is a key process that determines the regeneration potential and ecosystem stability in disturbed mountain spruce forests. Retention of standing and downed deadwood alters the balance of radiation, temperature, and humidity near the surface; however, quantitative evidence from exposed slopes in the Carpathians has been scarce. We therefore compared intact forest, deadwood-dominated forest, and open area on steep southeastern slopes of the Western Tatras (Slovakia) using continuous measurements from 2021 to 2025. Micrometeorological stations recorded global solar radiation, air and soil temperature, and humidity at multiple heights and depths; vapour pressure deficit (VPD) was calculated at 5 cm above ground. Differences among sites were assessed using non-parametric tests. Open areas received the highest radiation loads, resulting in extreme warming of the air near the ground (up to 34 °C at 5 cm) and intense soil heating (absolute maximum of 49 °C at – 2 cm). Intact forest reduced incoming radiation and maintained the most stable conditions. Deadwood-dominated stands represented an intermediate type but repeatedly buffered extremes: summer soil maxima remained below 26 °C, and air temperatures near the ground were several degrees cooler than in the open area. In winter, snow cover largely equalised conditions, while during snow-free episodes intact forest showed stronger nocturnal cooling, whereas deadwood stands preserved milder soil minima. VPD patterns followed the same gradient, with the shortest daily duration above the threshold of 1.5 kPa in intact forest, the longest in open area, and intermediate values in deadwood stands. Overall, deadwood-dominated forest approximates, and under certain circumstances even exceeds, the buffering capacity of intact spruce stands. We conclude that retention of deadwood-dominated forests mitigates heat and drought stress, reduces thermal extremes, and provides a low-cost, ecologically grounded adaptation strategy for mountain forest management in the context of climate change.