Kominoski J S, Pringle C M, Ball B A, Bradford M A, Coleman D C, Hall D B, Hunter M D
Institute of Ecology, University of Georgia, Athens, Georgia 30602, USA.
Ecology. 2007 May;88(5):1167-76. doi: 10.1890/06-0674.
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 macroinvertebrate 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.
由于预计物种丧失并非随机发生，因此了解那些我们预计会丧失的物种与其他物种相互作用从而影响生态系统功能的方式非常重要。我们测试了以丰富度和组成来衡量的凋落物物种多样性是否会影响碎屑基溪流中的分解动态。通过对单物种和混合物种叶包进行全因子分析（四种优势凋落物物种的15种可能组合；红枫[Acer rubrum]、北美鹅掌楸[Liriodendron tulipifera]、栗栎[Quercus prinus]和杜鹃花[Rhododendron maximum]），我们测试了单物种存在/不存在（累加）或物种相互作用（非累加）对叶包分解速率、凋落物化学变化以及微生物和大型无脊椎动物生物量的影响。总体而言，我们发现凋落物物种多样性对叶包分解速率有显著的非累加效应，这可以通过丰富度和组成来解释。含有较高凋落物物种丰富度的叶包分解速率更快，并且当四种凋落物物种中的任意两种或三种混合时，观察到了凋落物物种组成的拮抗效应。在凋落物化学变化以及微生物和大型无脊椎动物生物量方面，得到的结果不太一致。我们的结果表明，凋落物物种多样性的丧失将减少参与调节生态系统功能的物种相互作用。为此，在美国东南部，诸如东部铁杉（Tsuga canadensis）等物种的丧失以及河岸树种组成的预测变化可能会在景观尺度上对凋落物分解产生非累加效应。
