Relative
effects of macroarthropods and habitat on the chemistry of litter during
decomposition.
Abstract: During the decomposition
of terrestrial leaf litter, the concentrations of lignin, tannin, cellulose,
hemicellulose, nitrogen, and carbon are known to change. These chemical
changes have been associated with subsequent colonization and activity
of decomposer flora and fauna. Here, we report that chemical changes in
litter during the first twelve months of decomposition are affected by
macroinvertebrate activity. Moreover, chemical changes are associated most
closely with the activities of invertebrate predators. Using litter bags
that either excluded (fine mesh) or allowed access by (coarse mesh) macroinvertebrates,
we followed the concentrations of lignin, tannin, cellulose, hemicellulose,
nitrogen, and carbon in the litter of Liriodendron tulipifera, Quercus
prinus, and Rhododendron maximum in a North Carolina forest ecosystem.
We also compared chemical changes in these litters at a riparian site and
an upland site within the forest. The exclusion of macroinvertebrates decreased
concentrations of nitrogen and total phenolics in the litter of L. tulipifera,
increased concentrations of cellulose and condensed tannin in Q. prinus
litter, and increased the concentrations of condensed tannin in R. maximum
litter in the riparian zone. Although fine mesh bags excluded most macroinvertebrates,
the greatest effects of exclusion were upon ants and spiders, not macroinvertebrate
decomposers. Our data therefore suggest that predator-mediated changes
in the decomposer communities were responsible for observed shifts in litter
chemistry. Predator effects on litter chemistry were likely mediated by
their interactions with fungivorous and bacterivorous fauna. For example,
Collembola populations were 34% higher in litter bags from which
macroinvertebrates were excluded. Litter chemistries also differed between
the riparian and upland sites. For both L. tulipifera and R. maximum, effects
of habitat were limited to higher concentrations of condensed tannin in
the upland site. In contrast, habitat effects upon the litter chemistry
of Q. prinus were pervasive. Specifically, Q. prinus litter in the upland
habitat exhibited slower increases in lignin, more stable concentrations
of cellulose, slower increases in hemicellulose, higher concentrations
of total phenolics, and higher concentrations of hydrolysable tannins than
did litter in the riparian habitat. Overall, our data provide the first
evidence that predators in the litter of deciduous forests can influence
the chemistry of litter during the decomposition process.
Hunter, M. D., S. Adl, C. M. Pringle and D. C. Coleman. 2003. Relative effects of macroarthropods and habitat on the chemistry of litter during decomposition. Pedobiologia 47: 101-115.
Back to Literature Page
| Pringle's Home Page | University of Georgia | Odum School of Ecology |