EFFECTS OF BASE-CATION FERTILIZATION ON LITTER DECOMPOSITION IN A SUGAR MAPLE FOREST IN SOUTHERN QUEBEC

Application of base-cation fertilizers has been shown to increase tree growth and vigour in declining sugar maple (Acer saccharum Marsh.) st ands in southern Quebec but little is known about the effects of such fertilizers on litter quality or decomposition. Sugar maple foliage li tters from fertilized and unfertilized plots on a base-poor site and f rom a naturally base-rich site were incubated in litterbags of 1- and 3-mm mesh sizes on fertilized and unfertilized plots at the base-poor site. Mass loss of unfertilized litter was slower in fertilized than i n unfertilized plots, suggesting a negative effect of fertilization on the decomposer community. Faster mass loss of fertilized than unferti lized litter incubated in the same plot indicated that changes in litt er quality brought about by fertilization enhanced decomposition. Mass loss of fertilized litter on fertilized plots did not differ from tha t of unfertilized litter on control plots, indicating that although de composition processes are affected by fertilization the overall effect on decomposition is negligible. Mass loss was significantly, but only slightly, higher in large mesh than in small mesh bags indicating tha t larger soil fauna play a limited role in litter decomposition in thi s forest.