Spatial patterns of surface temperature are controlled by soil physical properties across geomorphological units in a European alpine meadow.

Understanding drivers of spatial patterns in soil surface temperature is essential to assess ecosystem vulnerability to climate change, particularly in alpine landscapes characterized by pronounced microclimatic heterogeneity that arise from complex topography, elevation gradients, and pedogenic processes. However, the role of underlying soil properties in modulating surface temperature dynamics remains poorly understood. This study investigates diurnal and nocturnal surface temperature patterns across geomorphological units in a European alpine meadow, emphasizing the roles of soil chemical and physical properties.

An intensive three-day field campaign was conducted in July 2024 near Pansier in the French Alps. Surface and subsurface soil temperature and moisture were recorded at 24 locations across five geomorphological units defined based on their solar radiation input and slope position: moraine ridge, moraine slope, alluvial plain, scree footslope, and scree slope. Soil profiles down to ~40 cm were sampled and analyzed for physical properties such as texture, bulk density, rock fragment content, and chemical properties such has soil organic carbon (SOC), total nitrogen (TN), and soil pH.

Distinct surface temperature patterns emerged for each geomorphological unit, with scree slopes exhibiting notable nocturnal variability and pronounced warming. Overall temperature patterns were associated with soil physical properties, especially sand and rock fragment content, rather than chemical properties. This finding was reinforced by the limited improvement in predictive models when chemical properties were included. Our study suggests soil physical properties play a dominant role in regulating surface thermal behavior in European alpine landscapes, and therefore should be preferentially considered in microclimate-based vulnerability assessments.