Consequences of ten-year abandonment in a subalpine grassland: soil and litter decomposition changes.

This article investigates the early-stage effects of woody species encroachment on soil properties and litter decomposition in a subalpine Nardus grassland in the western Italian Alps. After approximately 10 years of shrub and tree colonization following grazing abandonment, the encroached shrubland exhibited higher soil temperature and moisture, increased dissolved organic carbon, and greater microbial carbon and nitrogen in the soil compared to adjacent grassland, while other soil chemical properties remained largely unchanged. Using standardized Nardus litter to control for litter quality, the study found an accelerated decomposition rate in the shrubland, driven by enhanced microbial activity and microclimatic conditions, without significant differences in the chemical pattern of decomposition. These findings suggest that woody encroachment can rapidly alter soil microenvironment and microbial dynamics, potentially increasing ecosystem carbon loss during early succession stages, although longer-term shifts in soil chemistry and microbial functioning may require more time to manifest.