Regeneration plots

The natural regeneration of 25 selected tree species has been monitored inside circular sub-plots of 8m radii, located on a systematic grid inside each plot 1 to 12.

Systematic inventories of the regeneration stricto sensu (juveniles) were carried out on all the plots. They took place first in 1986, just before the beginning of logging operations, then in 1988, 1990, 1992 and finally in 1995. The implemented protocols underwent several modifications from one campaign to the other, as difficulties and new questions arose but some principles remained unchanged:

  • monitoring was restricted to a small number of species, for which botanical identification at early stages did not pose questions. Most of the data were collected on 25 species;
  • the inventory was made on circular sub-plots, with a radius of 4m, located at the nodes of a 20m by 20m grid: 64 sub-plots per plot 1 to12.

Various data were collected for each individual: DBH, exact measurement of height, characterisation of several environmental factors (light, densities and basal areas of grey species). These types of systematic inventory yielded some important results:

  • many important species have populations which clustered on a small spatial scale
  • seedlings are affected by a very high mortality rate 
  • the important “sapling” stage cannot be correctly assessed on a species basis due to the insufficient pool of monitored individuals.

Regeneration plots have been censused every 3-5 years with the last census in 2016.