THE EFFECTS OF MYCORRHIZAL ROOTS ON LITTER DECOMPOSITION, SOIL BIOTA,AND NUTRIENTS IN A SPODOSOLIC SOIL

We studied the effects of mycorrhizal pitch pine (Pinus rigida) roots on litter decomposition, microbial biomass, nematode abundance and ino rganic nutrients in the E horizon material of a spodosolic soil, using held microcosms created in a regenerating pitch pine stand in the New Jersey Pinelands. Pine roots stimulated litter decomposition by 18.7% by the end of the 29 month study. Both mass loss and N and P release from the litter were always higher in the presence of roots than in th eir absence. Nutrient concentrations in decomposing litter were simila r, however, in the presence and absence of roots, which suggests that the roots present in the with-root treatment did not withdraw nutrient s directly from the litter. The soil was slightly drier in the presenc e of roots, but there was no discernible effect on soil microbial biom ass. The effects of roots on soil extractable inorganic nutrients were inconsistent. Roots, however, were consistently associated with highe r numbers of soil nematodes. These results suggest that, in soils with low total C and N contents, roots stimulate greater activity of the s oil biota, which contribute, in turn, to faster litter decomposition a nd nutrient release.