Highlights The research community will play a key role in the post-2020 UNFCCC framework. GHG inventories must follow a rigid set of rules established by the UNFCCC and IPCC. To be policy relevant, the research community should understand these set of rules. The research and reporting communities should facilitate estimates comparability.

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Land-use change, Woody encroachment, Carbon sequestration, Soil carbon pools, Italy, Winter air temperatures HIGHLIGHTS  Woody encroachment over pasture can help mitigate the effects of climate change  Soil and biomass C pools were estimated in six areas with a chronosequence approach  Belowground C pools' (soil + belowground biomass) changes lead ecosystem C dynamics  Winter air temperatures are the best predictors for sites' overall SOC stock changes  Subsoil omission leads to substantial ecosystem C underestimation ABSTRACTWoody encroachment is a widespread phenomenon resulting from the abandonment of mountain agricultural and pastoral practices during the last century. As a result, forests have expanded, increasing biomass and necromass carbon (C) pools. However, the impact on soil organic carbon (SOC) is less clear. The main aim of this study was to investigate the effect of woody encroachment on SOC stocks and ecosystem C pools in six chronosequences located along the Italian peninsula, three in the Alps and three in the Apennines. Five stages along the chronosequences were identified in each site.Considering the topsoil (0-30 cm), subsoil (30 cm-bedrock) and whole soil profile, the temporal trend in SOC stocks was similar in all sites, with an initial increment and

under the influence of global climate change along a small altitudinal gradient and at short distance (Broll & Keplin 2005, Holtmeier 2009, Körner 2012. Mountain forests, and thus treeline ecotones, provide sev-ABSTRACT: 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 short-or 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.