Step 4: Assessment of trees sanitary status

To improve already existing models and build vigilance maps from IBS (see step 1) calibrated for the Haut-Languedoc territory, we performed a field campain to assess the sanitary status of two key tree species:

• The douglas fir (Pseudotsuga menziesii), the main production tree species in term of surface and economic value in the PNRHL territory and rather sensitive to drought
• The beech (Fagus sylvatica), an indigenous species linked to the Habitat of Community Interest we study in the FORECCAsT project

Douglas fir study

We measured 82 douglas plots, distributed in the Haut-Languedoc territory, with 72 including a soil pit (see step 3). In each of these sites, we formed forest plots by choosing 20 dominant or subdominant trees spirally dispersed from a centre localized near the soil pit.

Dendrometric measurements

In each forest plots, we measured:

• The diameter at breast height for the 20 trees we chose
• The height of the three bigger trees
• The age of the bigger tree with an increment borer
• The basal area of the plot

Measurement of a douglas fir diameter at breast height (Juliane Casquet - Pnr HL)

Extraction of a core sample with an increment borer to estimate the tree age (Juliane Casquet - Pnr HL)

Sanitary status measurement

We estimated the sanitary status of our tree plots by using two complementary protocols, the ARCHI (CNPF) and DEFIFOL (DSF) methods. We also checked whether some other anomalies were present on the trees, such as traces of necrosis, cracks or evidences of Fomes.

Observation of douglas fir crowns to measure their sanitary status (Juliane Casquet - Pnr HL)

Beech study

We measured 30 beech plots, all of them within Natura 2000 sites from the Haut-Languedoc Regional Nature Park and typical of the "Atlantic acidophilous beech forests with Ilex and sometimes also Taxus in the shrublayer" habitat of community interest (see step 2).

In each of these stes, we gathered some contextual data (slope, topography...), studied soil sub-surface (see step 3) and measured dendrometric and sanitary status variables similar to the ones we gathered in our douglas fir plots. In each plot, we also did a detailed flora inventory so that we could identify plants that are characteristic to this habitat and measure their cover. From this data, we deduced the conservation state of the habitat.

Wavy hair-grass (Deschampsia flexuosa), a grass species linked to this habitat (Juliane Casquet - Pnr HL)

Back to step n°3 - Building-up "FORECCAsT by BioClimSol - Go to step n°5