GROWTH OF CHESTNUT COPPICE IN FRANCE BASE D ON IFN DATA

The total standing woody biomass of sweet chesnut coppice is studied u sing IFN data (French National Forest Survey). To obtain pure coppiced standing, 374 sample plots are selected on 9 forest regions, represen ting 35% of measured sweet chesnut plots. The equation giving total ab ove-ground biomass of individual trees in relation to their girth at b reast height is applied to the plots. Using the radial increment of 5 yr, the biomass present 5 yr ago is computed with the same equation. W e consider data structure, and a general logistic model is applied to estimate height and biomass growth. The equations obtained are: domina nt height (m) = 13.8 x [1-exp(-0.130 x age)] biomass (t.ha-1) = 67 x [ 1-exp(-0.19 x age)]6.09. The mean biomass growth model gives a maximum current annual increment of 4.3 t.ha-1.yr-1 at 9 yr, and a maximum me an annual increment of 3 t.ha-1.yr-1 at 12 yr. The results below are t hose presented in a previous paper We show that forest regions have di fferent growth potentials, but the proposed models can explain these d ifferences. Future research work using the same data are proposed.