Choice of species to be regenerated or planted

Once the site diagnosis has been made on the basis of your floristic survey, it is interesting to know which species are appropriate for these environmental conditions. This information is particularly useful when choosing the species for the regeneration of a forest stand, whether by plantation or natural regeneration. The abilities are presented above in a synthetic but complete form.

Notions of aptitude of forest species

Each species is characterized by particular levels of tolerance with respect to the factors of the environment, which defines its self-ecology.

If the ecological conditions of the site coincide perfectly with the autology of a species, it is considered that this species meets optimal conditions of growth on the site. If one or another ecological factor becomes limiting (for example, a site that is a little too dry or too rich in limestone for the species, etc.), this does not necessarily mean that the species is not growing well. ), it does not necessarily mean that the species will not be able to grow on the site. To a certain extent, forest species are indeed able to cope with environmental stress. Of course, the more the stress increases, the more the negative consequences are felt at the level of the tree: decrease in growth, risk for stability, sensitivity to diseases, etc . It is therefore necessary to provide nuance.

Four levels of suitability have been defined in the Ecological Species File.

Optimum. The species is perfectly suited to the site in terms of vitality, stability and productivity. The species can be grown without restriction.

Tolerance. Certain characteristics of the site create a constraint for the vitality, stability or productivity of the species. For example: a slightly too wet soil limits the strength of the roots and predisposes the tree to windfall. It is therefore necessary to adapt silviculture to these constraints. In the above case, it could be by dynamizing silviculture to promote individual tree growth, which would shorten the revolution and limit the duration of exposure of adult trees to storm risks.

Extended tolerance. If it is not possible to produce quality wood on the site, the species should not necessarily be excluded. If it is capable of surviving and reproducing there, albeit with a derisory productivity or a prohibitive form, it can nevertheless contribute its services to the ecosystem or the main stand. In these situations, the use of the species is limited to an accompanying role for ecological or silvicultural reasons. It goes without saying that this class of suitability is reserved for species that are beneficial to the ecosystem by their fane, their cover, their associated biodiversity or any other positive characteristic (the case of the black alder on white clay in the Haute Ardenne, for example).

Exclusion. The species is unable to develop in the long term on the site, very sensitive to dieback, disease, windthrow, frost, etc. In other words, the environmental constraints are prohibitive.

Species suitability matrix

A suitability is defined by taking into consideration the three overriding environmental gradients; climate, trophic level and water level. The climatic conditions are formalized by bioclimatic zones. A suitability map by species provides information on bioclimatic suitability. For each climatic zone, the aptitudes of the species are represented within the ecogram: this is the hydro-trophic aptitude. When selecting a hydro-tropic level by clicking on a station in the ecogram, a suitability matrix is displayed on the right and allows to visualize on the one hand, the bioclimatic suitability (lines in the table), and on the other hand, the hydro-trophic suitability. This table allows an initial analysis from which a first selection of species is made. The final choice of species to be regenerated requires careful consultation of the species sheets, in order to take into account the particular sensitivities.

Comparison of suitability matrices for several hydro-trophic levels

It is possible to compare the suitability of all species for several hydro-trophic levels. After selecting a first hydro-trophic level by clicking on it (the selected level is displayed in red), a second click on another level while holding down the shift key will display a suitability matrix that takes into account the most constraining suitability of the two hydro-trophic levels. Species for which the suitability is not identical for these hydro-trophic levels are displayed with a gray background color.