Silver fir is one of the two most important conifers in the AURA region (220,000 hectares, or 9% of the forest production area, with 88 million m3 of standing timber). Stakeholders in the sector have identified two major economic challenges:

- The first concerns a difficulty encountered during the initial processing of wood due to the presence of water pockets in the logs, which leads to drying problems and therefore increased costs.

- The second concerns the sustainability of this forest resource in the AURA region due to an increase in dieback caused by extreme heat and repeated droughts.

Distribution of silver fir in the AURA region

Water pockets are areas of wetter wood located in the heartwood.

Figure 1: Water pockets visible on logs after felling.

Figure 2: Photo of the measuring device

Thanks to the acquisition of an electrical resistivity tomograph (ERT), we carried out non-destructive mapping of the humidity of the trunks of 128 fir trees located in 10 Auvergne forests with varied pedo-climatic conditions.

Figure 3: Examples of tomograms obtained (in red the areas of high resistivity, dry and in blue the areas of low resistivity, wet)

For this part of the project, we are currently setting up experiments aimed at characterizing the vulnerability of fir forests in the AURA region to drought with the aim of providing management elements to adapt this forest resource to climate change.