Reforestation And Natural Dynamics In The Subalpine Forests (Haut-Verdon, Southern Alps, France).

Reforestation and natural dynamics in the subalpine forests (Haut-Verdon, southern Alps, France). This study comes within the framework of the researches on the restoration of degradated forests. In France, the high altitude forest, which has been destroyed after centuries of pastoral use, was replanted 100 years ago in order to stabilize severely eroded soils. A century later, we try to measure the present state of reforestation on a southern Alps site. The objective was to point out the natural colonizing processes and the reforestation impacts (success or failure) on the present state of the forest at its upper limit. This research is based on two concerns: 1) analysis of some archives documents providing informations on the reforestation timing and wooded areas evolution; 2) dendrochronological analysis of the upper forest limit and tree-line stands to estimate the stand ages and the influence of some environmental factors on tree growth. The results indicate that outlying stands at the tree-line above the present forest limit are remnants of reforestation stages. Most of the planted trees did not survive on the mountain tops. Natural regeneration did not take over the plantation. The altitudinal climatic constraint cannot be accounted as a limiting growing factor at this site. It seems that the reforestation failure at higher altitudes was rather caused by substrate changes from 2000 m and above. Below this level, forest restoration has been successful even on unfavourable lands, like ancient pastures. Within the planted forest, natural processes contribute to reforestation.