Grasslands of the Massif Central: how to measure their adaptation to the climate

An observatory launched in the Massif Central is monitoring 150 plots to link plant diversity, soils, climate and livestock farming practices. The first surveys are building a basis for comparison, not yet a validated adaptation method.

In the Massif Central, 150 grassland plots spread across thirty volunteer farms are part of a new observatory. Launched in summer 2026, the monitoring aims to bring together analyses of plants and soils, satellite images and farmers’ practices to understand how these environments respond to variations in the climate. The monitoring thus links what grows, the soil that supports it and the decisions made on each farm.

Grassland is measured in more ways than by the quantity of grass

Researchers from INRAE’s Grassland Ecosystem unit in Clermont-Ferrand collect grass and soil samples. The samples are intended to identify the plants present, examine their chemical composition and that of the forage, and study the soil, particularly its capacity to store carbon. Roots and other soil components are also sampled.

These observations do not all describe the same thing. Biomass indicates the quantity of vegetation produced. Plant diversity concerns the species present and their variety. The composition of the forage and the properties of the soil provide further information. A grassland that produces a lot of grass is therefore not necessarily one in which diversity or ecological functions are best maintained.

To interpret these measurements, the observatory must also take account of how the plots are managed. Satellite images provide an overview of the areas, while farmers supply information about their practices. By comparing these with field analyses, researchers are seeking to distinguish the effects of climate from those of agricultural use. This distinction is essential: a change observed in a grassland cannot automatically be attributed to the weather if practices have changed at the same time.

Comparing environments without confusing presence with trends

The network covers ten areas, from the Morvan to the Larzac, and draws on thirty farms. This geographical diversity makes it possible to monitor grasslands in different contexts, but does not mean that each area is represented by a large number of farms. The plots are the units being observed; the volunteer farms provide the agricultural framework for the monitoring.

Repeated observations over time are what can make the variations meaningful. A single sample describes a state at a given moment. Comparable surveys can then show whether vegetation, soils or practices are changing, and under what conditions. This is why setting up an observatory does not, in itself, constitute a finding about grasslands’ resistance to drought or heat.

An earlier study by INRAE and the CNRS helps explain why researchers are also interested in the characteristics of plants. Conducted on 150 German grasslands between 2008 and 2020, it examined “functional traits”: characteristics such as leaf size or growth rate, which influence how species respond to their environment and coexist. In this German network, the scientists also linked this diversity with fertilisation. In the most intensive situations described by INRAE, increased inputs no longer brought any additional plant production; instead, they were accompanied by greater nutrient losses through infiltrating water and increased sensitivity to climate hazards. The value lies in looking at production and ecological functioning together. This work concerned a different network and another region: its findings are not those of the new French observatory.

From measurement to realistic farming choices

The aim is ultimately to produce information that will help farmers develop adaptation strategies. The project leaders are considering a decision-support tool in the form of a website or an app that could be launched within three years. This is a stated objective, not a service that is already available, nor a guarantee that the data will lead to a single method for all farms.

Recommendations will need to take local conditions into account. The European Environment Agency points out that practices that benefit biodiversity can also contribute to climate adaptation, but must be tailored to the soils, climate, landscapes and specific aims of each environment. A measure that is beneficial in one context cannot necessarily be transferred unchanged to another.

Decisions also have practical consequences for farms. Some practices require more work and planning, or a change to the business model; short-term agricultural leases can discourage long-term commitments. The ecological benefits sought therefore need to be weighed against production, labour and land-use duration constraints. Scientific knowledge can inform these trade-offs, but does not replace them.