Warmer temperature promotes the contribution of invertebrate fauna to litter components release in an alpine meadow on the Qinghai-Tibetan Plateau

How warming and invertebrate fauna concurrently influence litter carbon and nutrient turnover in alpine meadow is still poorly known. Using a litterbag technique, we evaluated the effects of temperature (ambient temperature vs. warming temperature) × mesh (fine mesh without invertebrate fauna access vs. coarse mesh with invertebrate fauna access) on litter decay (i.e., carbon and nitrogen release, lignin and cellulose degradation) across two typical seasons (cold season vs. warm season) in an alpine meadow ecosystem on the Qinghai-Tibetan Plateau. Our results showed that the whole-soil-profile warming significantly increased litter cellulose degradation (+47%), but less affected the decay of other litter components (i.e., carbon, nitrogen, and lignin: + 7–18% increase). The loss of nitrogen and lignin from litter significantly increased by ca. 2 times in the presence of invertebrate fauna. Moreover, the release of all litter chemical components was significantly faster (by 1.5–5.2 times) in warm season than in cold season. Further, litter carbon release and lignin degradation rates were markedly influenced by the interacting effects of mesh × season, and mesh × temperature, respectively. Overall, these findings highlight the importance of invertebrate fauna as a commonly overlooked co-determinant of the warming effect on litter decay patterns in cold biomes; the changed release rates of litter components in the context of on-going warming may have far-reaching effects on carbon and nutrient cycling in alpine ecosystems.