ORGANIC MATTER AND NUTRIENT DYNAMICS OF THE LITTER LAYER ON A TWO CHESTNUT STANDS IN HONFRIA AREA, SPAIN

The aboveground biomass, litterfall and its accumulation, litter weight loss due to decomposition and nutrient pools in relation to soil properties were analysed in two Castanea sativa Mill. stands in order to better understand the recycling of elements associated with the turnover of organic matter. The two stands were a chestnut grove and a chestnut coppice. The aboveground biomass and the nutrient content were estimated by harvesting ten trees in the chestnut coppice stand. The results indicate a total biomass of 125.1 Mg ha^-1. In order to establish regression equations the best fit was obtained by applying the allometric method Y = ae^bx (Y = total aboveground biomass, X is DBH). The litter fall was 5.14 Mg ha^-1 yr^-1 in the chestnut coppice stand and 4.80 Mg ha^-1 yr^-1 in the chestnut grove stand. The leaves are the main vector of the potential return of all nutrients to the holorganic horizon in both stands, followed by flowers for N and K, branches for Ca, fruits for P and cupules for Mg in the chestnut coppice stand and the fruits for N and P, branches for Ca, cupules for Mg and K in the chestnut grove stand. Considering both total litter and leaves separately, higher K (Jenny’s decomposition constant) and Ko (Olson’s decomposition constant) values were estimated for leaves alone than for total litter. Towards the end of the thirty months of observation the loss of dry matter was 65% in the chestnut coppice and similar to the chestnut grove stand. The decomposition rates of leaves confined to litterbags for the first year were lower than those obtained under natural conditions (K=0.45, Ko=0.80 under natural conditions for chestnut coppice stand and K=0.45, Ko=0.81 for chestnut grove stand).