Effects of land use-induced vegetation and topography changes on soil chemistry in the Southern Alps (Ticino, Switzerland)

Abstract

Effects of land use changes on chemical soil properties were studied in a southern alpine valley of Ticino, Switzerland by analysing three different land cover-topography units: (i) natural forested slopes (NFS); (ii) deforested, cultivated terraces (DCT), and (iii) reforested, abandoned terraces (RAT). Whereas NFS represents the natural reference state with negligible anthropogenic influence, DCT corresponds to intense agricultural utilization, and RAT refers to a post-cultural natural evolution after terrace cultivation. Land use-induced changes in vegetation cover and topography (i.e., terracing) had a clear influence on chemical soil properties. The presence or absence of  the European chestnut (Castanea sativa Mill.), one of the main soil acidifying agents in the study area, clearly affected soil acidity, soil organic matter (SOM), and nutrient status. Compared to the vegetation change, terracing has  a less obvious effect on soil chemistry. A greater effective rooting depth and a flat microtopography on terraces lead to a rapidly increased SOM accumulation due to better growing conditions for trees. Thus, the reforested, abandoned terraces develop peculiar soil chemistry conditions after 36 to 46 years of abandonment only.