The relative imprint of forming factors on soil characteristics in a recently deglaciated area: concerns about chronosequences approach

In high-altitude environments, most of the debris-free glacier forelands are increasingly widening and the bare surfaces left by retreating glaciers offer the opportunity to investigate the evolution of soil through time. The main aim of this study is to discuss the applicability of a chronosequence approach in a deglaciated area, by considering the role of different soil forming factors. A study case has been selected (Alpe Veglia, Lepontine Alps), where field and laboratory characterizations were performed along a transect of 12 soil profiles from the proglacial area of the Aurona Glacier to the Alpe Veglia hollow, crossing different age glacial deposits. The results of soil physical and chemical analyses underline a time-trend of soil properties. On the other hand, even if the soil properties variability along the transect can be mainly explained according to the soil chronosequence approach, the data seem to highlight how the various soil forming factors (e.g. parent material, relief, vegetation) influence soil features, partly masking the effect of the time factor inducing a divergence from a traditional chronosequence. In particular, the morphology of the surrounding reliefs, depending on bedrock lithologies and structures, and the geomorphic dynamics seem to affect soil formation and evolution.