Contrasting vegetation height and elevation shape near-surface thermal responses more strongly than slope orientation during summer in northern Patagonia

Abstract

Forests in temperate mountain regions are increasingly exposed to extreme heat. Near-surface microclimates, shaped by vegetation and topography, influence forest regeneration, fuel dynamics, and disturbance feedbacks. We examined how daily warming rates, maximum temperatures, and cooling rates differ between microsites contrasting in vegetation height, elevation, and slope orientation during summer, and whether these differences increase under higher summer temperatures. We deployed a network of temperature loggers in the Río Manso Valley (northern Patagonia), recording summer temperatures at 15-minute intervals. Using a paired sampling design, we compared six environmental contrasts representing forest versus shrubland, low versus high elevation, and north- versus south-facing slopes. Following a contrast-wise approach, we used linear mixed-effects models to quantify daily differences in thermal metrics between paired microsites and assessed how these differences scaled with maximum daily temperature at the warmer site within each pair. Summer thermal sensitivity varied strongly across environmental contrasts. Differences associated with vegetation height and elevation were larger and more consistent than those associated with slope orientation. Across all contrasts, differences in warming rates, maximum temperatures, and cooling rates increased with rising summer temperatures, indicating that microclimatic divergence among microsites amplifies under heat extremes. By quantifying near-surface thermal sensitivity across paired environmental contrasts, our study provides empirical information relevant for modelling microclimate-sensitive ecological processes under climate change, particularly in comparable temperate mountain systems.