INDIRECT EFFECTS OF LITTER ON WOODY SEEDLINGS SUBJECT TO HERB COMPETITION

We tested the hypothesis that litter indirectly enhances the establishment of woody seedlings in oldfields, because litter reduces the intensity of herb competition. We counted and measured the woody seedlings growing in experimental plots with different amounts of litter of Solidago sp., or leaves of Quercus alba, and in plots with the dominant herb removed. We also conducted a factorial experiment in a greenhouse to test the effect of water availability, litter, and competition on the growth of seedlings of Ailanthus altissima. The results showed a strong negative effect of herb competition and a positive indirect effect of litter on woody seedling establishment. Litter had only a marginal effect on the number of seedlings established in the field. The removal of the dominant herb increased woody seedling size. Dense oak leaf litter reduced the cover of herbs and increased the size of the woody seedlings. In the greenhouse, litter reduced the density and biomass of herbs, thus improving the growth of the woody seedlings by reducing competition. We found evidence of a possible complex interaction. In which the presence of trees that produce the litter affect the competition between herbs and woody seedlings from a distance.