Dpto. Biología y Geología, Campus de Excelencia Internacional Agroalimentario (CEIA3), Universidad de Almería, Ctra. Sacramento s/n, La Cañada, 04120 Almería, Spain.
Sci Total Environ. 2013 Aug 1;458-460:197-208. doi: 10.1016/j.scitotenv.2013.04.004. Epub 2013 May 4.
Terrestrial plant litter is important in sustaining stream food webs in forested headwaters. Leaf litter quality often decreases when native species are replaced by introduced species, and a lower quality of leaf litter inputs may alter litter decomposition at sites afforested with non-native species. However, since detritivore composition and resource use plasticity may depend on the prevalent litter inputs, the extent of the alteration in decomposition can vary between streams. We tested 2 hypotheses using 2 native and 3 introduced species of tree differing in quality in 4 Iberian regions with contrasting vegetational traits: 1) decomposition rates of all plant species would be higher in regions where streams normally receive litter inputs of lower rather than higher quality; 2) a higher resource-use plasticity of detritivores in regions vegetated with plants of lower litter quality will cause a greater evenness in decomposition rates among plant species compared to regions where streams normally receive higher-quality plant litter inputs. Results showed a highly consistent interspecific ranking of decomposition rates across regions driven by litter quality, and a significant regional effect. Hypothesis 1 was supported: decomposition rates of the five litter types were generally higher in streams from regions vegetated with species producing leaf litter of low quality, possibly due to the profusion of caddisfly shredders in their communities. Hypothesis 2 was not supported: the relative differences in decomposition rates among leaf litter species remained essentially unaltered across regions. Our results suggest that, even in regions where detritivores can be comparatively efficient using resources of low quality, caution is needed particularly when afforestation programs introduce plant species of lower litter quality than the native species.
陆生植物凋落物对维持森林集水区溪流食物网至关重要。当本地物种被引入物种取代时，凋落物质量通常会下降，而输入较低质量的凋落物可能会改变非本地物种造林点的凋落物分解。然而，由于碎屑分解者的组成和资源利用可塑性可能取决于普遍的凋落物输入，因此分解的改变程度可能因溪流而异。我们使用来自 4 个具有不同植被特征的伊比利亚地区的 2 种本地和 3 种引入树种，检验了 2 个假说：1）在通常接收较低质量而不是高质量凋落物输入的地区，所有植物物种的分解速率都更高；2）在以低质量凋落物植物为特征的地区，碎屑分解者具有更高的资源利用可塑性，将导致植物物种之间的分解速率更加均匀，而在通常接收高质量植物凋落物输入的地区则不会。结果表明，凋落物质量在很大程度上决定了跨地区物种间分解速率的一致分类，这表明存在显著的区域效应。假设 1 得到支持：在以低质量叶凋落物为特征的地区，五种凋落物类型的分解速率通常较高，这可能是由于其群落中石蚕蛾类的大量存在。假设 2 不成立：在不同地区，叶片凋落物物种之间的分解速率差异相对不变。我们的结果表明，即使在碎屑分解者可以相对有效地利用低质量资源的地区，也需要特别小心，特别是在造林计划引入比本地物种质量更低的植物物种时。
