The Influence of Experimental Acidification on Needle Litter Decomposition in a Picea abies L. Forest

The effect on litter decomposition rates was studied after annual additions for four years to the forest floor of sulfuric acid (64 kg S.ha(-1)), sulfur powder (64 kg S.ha(-1)), and in the first year limestone (dolomite) powder (412 kg Ca+230 kg Mg.ha(-1)). The litter was Norway spruce needles which were incubated in the field in litter-bags. Drastic reductions in decomposition rates were observed and the addition of diluted acid caused a rate reduction to 66 % of that in control and the additions of sulfur powder a reduction to 80 %. The effect of the sulfur powder on litter mass-loss rate appeared to be delayed and could not be noted until one year after the first addition. No effect could be seen of the limestone powder.