Nonadditive effects of leaf litter species diversity on breakdown dynamics in a detritus-based stream
Abstract:
Since species loss is predicted to be nonrandom,
it is important to
understand the manner in which those species that we anticipate losing
interact with other species to affect ecosystem function. We tested
whether litter species diversity, measured as richness and composition,
affects breakdown dynamics in a detritus-based stream. Using
full-factorial analyses of single- and mixed-species leaf packs (15
possible combinations of four dominant litter species; red maple [Acer
rubrum], tulip poplar [Liriodendron tulipifera], chestnut oak [Quercus
prinus], and rhododendron [Rhododendron maximum]), we tested for
single-species presence/absence (additive) or species interaction
(nonadditive) effects on leaf pack breakdown rates, changes in litter
chemistry, and microbial and macroinvertebrate biomass. Overall, we
found significant nonadditive effects of litter species diversity on
leaf pack breakdown rates, which were explained both by richness and
composition. Leaf packs containing higher litter species richness had
faster breakdown rates, and antagonistic effects of litter species
composition were observed when any two or three of the four litter
species were mixed. Less-consistent results were obtained with respect
to changes in litter chemistry and microbial and macro invertebrate
biomass. Our results suggest that loss of litter species diversity will
decrease species interactions involved in regulating ecosystem
function. To that end, loss of species such as eastern hemlock. (Tsuga
canadensis) accompanied by predicted changes in riparian tree species
composition in the southeastern United States could have nonadditive
effects on litter breakdown at the landscape scale.
Kominoski, J.S., C. M. Pringle, B. A. Ball, M. A. Bradford, D. C. Coleman, D. B. Hall and M. D. Hunter. 2007. Non-additive effects of leaf litter species diversity on breakdown dynamics in a detritus-based stream. Ecology 83: 1167-1176.
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