Abstract ID: 3.11361 | Accepted as Talk | Talk/Oral | TBA | TBA

Mountain ecosystems are highly sensitive to climate change, with warming temperatures driving shifts in species distributions and altering community composition. However, recent research highlights the role of microclimatic variation in modulating these responses, particularly in alpine environments where fine-scale temperature differences can shape local biodiversity patterns. In addition to climate change, land-use shifts—such as the abandonment of traditional pastoral activities—further influence plant community dynamics, often leading to encroachment by shrubs and trees. Understanding how microclimatic factors, especially soil temperature, mediate these transformations is crucial for predicting biodiversity changes in alpine landscapes. In this study, we investigate the direct effects of soil temperature on plant distribution and community structure in a high-mountain environment. We analyzed vegetation dynamics across 84 nested plots (with size ranging from 2.25 cm² to 4 m²) along an elevational gradient in the Apennines (Italy), monitored 4 times over a 20-year period (2005–2025). Soil temperature was recorded hourly using 40 dataloggers buried at 10 cm depth. From these data, we derived key microclimatic variables, including annual mean temperature, snow cover duration, growing season length, and growing degree days. These variables were then spatialized across the study area using boosted regression trees (GBM) and considering the following predictors: elevation, topographic wetness index, eastness, and northness. Changes in plant community composition were assessed using trajectory analysis. Linear mixed models were applied to evaluate the influence of soil temperature-related variables on community variation (angle and magnitute of the trajectory). Our findings reveal that compositional changes is strongly scale-dependent: in small plots, changes are largely stochastic, whereas larger plots (≥0.25 m²) exhibit more consistent temporal trends. Notably, plots with prolonged snow cover and low growing degree days showed the highest variation in species composition and the greatest increase in species richness. These results underscore the critical role of soil microclimate in shaping alpine biodiversity responses and highlight the vulnerability of cryophilic plant communities to global change.