In ECOPICS, we will use elevational gradients as a time-for-space substitution. The altitudinal gradient will allow us to examine soil quality in diverse vegetational communities and climates in a small spatial area, thus reducing heterogeneity due to substrate. Due to the expected contrasting changes in root/shoot biomass and traits, and in faunal/microbial community composition, along the temperate and tropical elevation gradients, we hypothesize that these changes will influence three major components of C sequestration, i.e. root C input, litter decomposition rates and C stabilization in soil aggregates. We will measure how variations in root traits and microbial community composition relate to litter decomposition rate, SOC and to environmental variations along the temperate/tropical elevation gradients. Overall, results should provide us with key clues as to the mechanistic bases behind major shifts in C and nutrient cycles along elevation gradients and the critical role of the (largely overlooked) belowground components of ecosystems in these functional shifts. As well as an elevational gradient, will investigate a gradient linked to the types of landuse often observed on mountains. We will use the same methodologies to study both types of gradients.

Fieldsites are located at Mexico’s highest mountain, the volcano Pico de Orizaba (5640 m elvation) and in France at the Massif de Belledonne (2977 m). Vegetation will range from lowland montane to subalpine forest, shrubland and grassland, to alpine herbaceous communities beyond the treeline. At each elevation studied, a landuse gradient will be investigated, ranging from disturbed tourist trails, to 40 year old logged forest to undisturbed forest. Soil physical and chemical properties (e.g. soil organic carbon, DSOC, N and certain inherent chemical properties) will be measured using the same field and laboratory protocols in the two countries. We will evaluate species, root traits, and decomposition in plant communities along the gradients. Soil fauna sampling  will focus on the identification and estimation of native and exotic earthworm communities at each elevation in an aim to determine the link between plant species, root traits, earthworm community size and composition and soil aggregation. We will examine how vegetation alters rainfall infiltration and DSOC transport along biotic soil macropores (formed from root channels and earthworm burrows). We will investigate litter decomposition and how it is linked to microbial and faunal communities, as well as C sequestration. We will use a phylogenetic approach to assess microbial diversity, thus providing additional insights into the ecological and evolutionary processes that organize these communities.

A socio-economic impact assessment will allow us to estimate the impacts of ecotourism on local communities and working with these stakeholders, we will draw up a management plan, taking into account community needs and ECOPICS results on soil quality.