Soil properties as indicators of treeline dynamics in relation to anthropogenic pressure and climate change

Mountain forests, treeline ecotones included, provide numerous ecosystem services. However, different drivers heavily impact the treeline areas, in particular anthropogenic pressure and climate change. Any change affecting the aboveground portion of terrestrial ecosystems automatically influences their belowground part, i.e. soil and soil organisms. Therefore, the focus of the present paper is on the soil resource that provides multiple ecosystem services, such as carbon storage, water filtration, food and biomass provisioning, biodiversity, maintenance, etc. Soil physical, chemical, and biological properties can be very helpful as indicators of ecosystem services in mountain regions. A selection and integration of appropriate indicators of soil quality is thus needed for soil monitoring and assessment in treeline areas. In this paper, results of case studies from mountain regions in Bulgaria, the Czech Republic, Italy, Romania, and Slovakia are presented. From these studies, it emerges that soil organic matter (content and quality), pH, and microbial parameters show significant changes in response to anthropogenic pressures and/or climate change. These indicators of soil quality, either in the shortor in the long-term, can thus be used as reliable and sensitive tools for monitoring actions. However, it is advisable to integrate this basic set with additional indicators that can be further selected in relation to specific conditions, such as geographical area, lithological substrate, land use, and management practices.