Spatiotemporal variations of alpine climate, snow cover and phenology

Understanding the relationships between vegetation phenology and its seasonal drivers under varying site conditions is of high interest in mountain areas, since alpine ecosystems are assumed to be particularly sensitive to climatic changes. Through the joint analysis of NDVI, snow metrics, and climate data at 250 m and 2 km spatial resolution, respectively, we aim at identifying their temporal and spatial variability and statistical inter- and intra-annual relationships on an alpine-wide scale. Apart from clear patterns in the vegetation and snow metrics related to topography, a negative relationship of mean March NDVI to snow cover duration (SCD) in the preceding months was detected, indicating a high sensitivity of green-up to snow accumulation and melt. In contrast, positive correlations between early winter SCDs and late summer NDVI indicate a lagged water storage effect. On the local scale of South Tyrol, climate variability interacted with topography could explain on average 30% of NDVI variations from late-October till late-May.