Summary: Leaf litter directly and indirectly influences
understory vegetation in plant communities.
Decomposition of litter can immobilize some
nutrients while releasing others and can also
produce allelopathic chemicals (Klemmedson
et al. 1985). Accumulated litter intercepts light,
affects soil microclimates, and can trap seeds
or form physical barriers to plant emergence
(Facelli and Pickett 1991). Litter also can be a
filter in some plant communities that regulates
fine-scale species richness and distributions
by affecting plant germination and establish-
ment (Sydes and Grime 1981). In a New York
deciduous forest, for example, Beatty and Sholes
(1988) found that removal of thick litter layers
from treefall pits caused species composition
of pits to converge with that of treefall mounds.
All forbs colonizing litter-free pits had previ-
ously been restricted to mounds.
In a variety of ecosystems, litter addition