Evolution d'une garrigue de quercus coccifera L. soumise a divers traitements: Quelques resultats des cinq premieres annees

Summary

In 1969, several experiments were carried out in a Quercus coccifera garrigue, in order to clear up the role of man's action. Two of these experiments are described here:

• - one based on the repeated action of fire with two controlled factors (period of fire setting and fire frequency).

• - the other simulating rational grazing after mechanical scrub-clearing, with two controlled factors (fertilization and cutting period).

The experimental results presented here are those obtained from 1969 to 1974, by observation along lines. They concern the species number and the behaviour of certain species; it appears from these results:

• - Whatever the experiment and the treatment, the number of species increases from 1969 to 1974.

• - The number of species is higher with ‘autumn fire’ than with ‘spring fire’, and with ‘fire every six years’ than with other fire frequencies (two and three years).

• - The number of species is the highest with mean fertilization and the latest cutting time.

• - The number of species in a reference line varies very much year after year, it follows that only the increase of the number of species with mean fertilization and the latest cutting time is higher than that of the reference ones.

The stability of the original flora is noteworthy but the species frequency is modified. A few species appear, these ones are rare in the Quercus coccifera garrigue or come from the surrounding vegetation.

The experiment ‘fire’ has not yet allowed to obtain by succession, the Brachypodium ramosum sward-hypothesis currently supported — the experiment ‘cutting’ has led towards a formation in which the grasses predominate. These experiments are now in progress.