In July 1983 a forest fire above Mustair destroyed some 50 ha of subalpine forest stands at 1800–2200 m a.s.l. The subsequent process of natural reforestation was documented with comments relating to fire intensity, soil changes and development of vegetation, and compared with the development of a man-made afforestation.
About half of the study area had suffered severe crown and ground fire, the other half only crown fire with slight surface fire. Processes of erosion were scarcely detectable. Where the ground fire had been severe, the vegetation had to invade the area anew. Here fireweed (Epilobium angustifolium L.) became dominant. Where there had been only slight ground fire, surviving roots of shaggy woodreed (Calamagrostis villosa (Chaix) Gmelin) sprouted rapidly and soon produced a closed carpet of vegetation.
The crop of young trees had been completely destroyed and had to re-establish itself from seedlings. Natural regeneration began very slowly. After twelve years, it included eleven species. Broadleaves, with 1449 plants per ha were the most numerous; all the conifers together totalled only 581 plants per ha. Of these, various shrubs comprised 41 %, aspen 25 % and larch 20%. It will be a long time before the natural regeneration catches up with the man-made afforestation in terms of number and size of plants, although this showed a loss of 30% within eleven years and growth often stagnated as a result of planting shock.
At many high altitude sites it is urgent to restore the forest's function as a protection against snow movement as quickly as possible, e.g., in combination with temporary avalanche defence structures. The regrowth of the forest must be accelerated through artificial afforestation at critical points only. Planting with the more protective conifer species allows leapfrogging the less protective phase of broadleaf growth. However, it is not necessary to re-stock whole areas where there has been a fire.