EVOLUTION OF PHENOLIC PATTERNS IN PLANTS AND ASSOCIATED LITTERS AND HUMUS OF A MOUNTAIN FOREST ECOSYSTEM

The pattern of phenolic polymers (tannins) and monomers (phenolic acid s, flavonoids) was followed from living organs (leaves and roots) of P icea abies (L.) Karst and Vaccinium myrtillus (L.) to litter types and humus, in two stands (1630 and 1860 m) of a mountain forest of Northe rn Alps (France). Quantitative and qualitative criteria were found to characterize species: abundance of tannins in bilberry; and, presence of p-hydroxyacetophenone a specific (and variable) metabolite in spruc e needles. Compared to green foliage, an important loss of monomeric c ompounds in brown foliage was observed, when tanning activity greatly increased. As biodegradation proceeded the amounts of the degradation intermediates (protocatechuic, vanillic acids) increased in litters, a nd the influence of phenol-rich plants, such as bilberry, on organic l ayers was expressed by higher amounts of tanning activity and phenolic acids under bilberry cover. Because of its specificity and abundance, special attention might be given to p-hydroxyacetophenone in spruce f orest floor. Control of phenolic compounds dynamics by their structure was equally emphasized.