SICCCUB - Monitoring the impact of climate change and land use change on biodiversity and the functioning of mountain ecosystems

By complementing and linking with the spatio-temporal observatory of biodiversity and the functioning of mountain socio-ecosystems (Orchamp), SICCCUB will enable long-term monitoring of biodiversity dynamics and ecosystem functions

Approaches

SICCCUB project investigated the relationships between: past land-use practices and landscape history, tree recruitment dynamics, and biodiversity and ecosystem functions (such as carbon storage and organic matter recycling).

These functions underpinned the provision of ecosystem services including wood supply, soil quality regulation, reduction of greenhouse gases in the atmosphere, and seed dispersal. The project also provided insights into cultural services related to the aesthetic, cultural, and symbolic representations of nature dynamics in mountain areas.

The project focused on the Orchamp observatory, which consists of permanent plots distributed along altitudinal gradients in the Alps and the Pyrenees (see https://orchamp.osug.fr/ for a detailed description). Orchamp provided a unique framework to analyze mountain biodiversity and ecosystem functioning.

The project quantitatively described current and past land uses of Orchamp plots. Historical sources such as military maps (1818–1866) and Napoleonic cadastral maps (1807–1850) were used to describe past land uses. More recent sources such as historical aerial photographs, land-use and habitat maps, forest management archives, and pastoral surveys were also mobilized.

The Orchamp observatory is based on altitude gradients of around 1000 m with permanent plots (30 x 30 m) spaced at around each 200 m of elevation intervals. The observatory also has measurements at landscape and catchment scale, based on remote sensing data and current mapping data.

The SICCCUB project will provide a quantitative description of past and present uses of the plots. “Cartes d’état-major” (drawn up between 1818 and 1866) and the “cadastre napoléonien” (drawn up between 1807 and 1850) will be used to describe past uses around the plots. For more recent uses, old aerial photographs, use and habitat maps, forest management archives and pastoral surveys will be used.

The project monitored tree recruitment and seed production dynamics across altitude. Biodiversity surveys (aboveground and belowground), complementary to Orchamp’s mandatory eDNA monitoring, were carried out to cross-validate methods and enrich reference databases.

Results

Effect of forest stand structure on soil biodiversity

Forest structure and composition were less important than abiotic variables such as climate and soil chemistry. However, the diversity of certain groups was closely linked to forest structure.

Effects of land use change and climate change on biodiversity

The vectorisation of the landscape structure in the vicinity of the three-step plots (1850 - 1950 - present) enabled the partially decorrelated study of the effects of land use change and climate-related changes. The data enabled analysis of the effect of the current landscape structure and that of 1950 on the biodiversity of springtails and protists by testing landscape metrics on buffers of different radii. Thus, the species richness of epigeal, endogeal and total springtails is better explained by the structure of the old landscape (1950) than the current one (2020).

 Comparison of field sampling and mDNA sampling of soil macrofauna

• Consolidation of the mDNA reference database
• Richness estimates made using mDNA approaches are underestimated compared to field approaches.

Change in tree fertility

Regeneration and seed production are marked by very high interannual variability, which makes it difficult to estimate fertility with a short time series collected in the SICCCUB project.

These measurements will continue beyond the project and will therefore offer a unique perspective on changes in tree fertility. They have already been used in large-scale data syntheses, where it is easier to extract reliable information than from a limited sample of plots along a gradient.

Participants

INRAE units involved

• UR LESSEM - Laboratoire Ecosystèmes et Sociétés En Montagne
• UMR DYNAFOR - Dynamiques et Écologie des Paysages Agriforestiers
• UR EFNO - Unité de recherche Écosystèmes Forestiers
• UMR Eco&Sols - Écologie fonctionnelle & biogeochimie des sols & des agro-ecosystemes - IRD / Institut Agro Montpellier / Cirad

Partners

• LECA - Alpine ecology laboratory - CNRS