title: Leaf litter decomposition of native and introduced tree species of contrasting quality in headwater streams: how does the regional setting matter?
abstract: 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.
authors: Dpto. Biología y Geología, Campus de Excelencia Internacional Agroalimentario (CEIA3), Universidad de Almería, Ctra. Sacramento s/n, La Cañada, 04120 Almería, Spain. jjcasas@ual.es
authors: J Jesús
authors: JJ
authors: Casas
authors: Aitor
authors: A
authors: Larrañaga
authors: Margarita
authors: M
authors: Menéndez
authors: Jesús
authors: J
authors: Pozo
authors: Ana
authors: A
authors: Basaguren
authors: Aingeru
authors: A
authors: Martínez
authors: Javier
authors: J
authors: Pérez
authors: José M
authors: JM
authors: González
authors: Salvador
authors: S
authors: Mollá
authors: Carmen
authors: C
authors: Casado
authors: Enrique
authors: E
authors: Descals
authors: Neftalí
authors: N
authors: Roblas
authors: J Antonio
authors: JA
authors: López-González
authors: J Luis
authors: JL
authors: Valenzuela
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D020387:Food Chain; D040362:Geographic Information Systems; D007313:Insecta / Q000378:metabolism / Q000502:physiology*; D058865:Introduced Species; D018515:Plant Leaves / Q000378:metabolism*; D025341:Principal Component Analysis; D045483:Rivers / Q000737:chemistry*; D013030:Spain; D014197:Trees