The Effect Of Light Radiation On Litter Decomposition In An Alpine Meadow Of The Tibetan Plateau

Litter decomposition connects the aboveground and underground, which is an important process of nutrient cycles and energy flow in the ecosystem. Therefore, litter decomposition plays a very important role in ecosystem functioning. Light radiation, mainly UV-B, has been proved to be a factor, which accelerate litter decomposition in arid and semi-arid regions. However, litter has been documented in a Tibetan alpine meadow, where it has both high UV-B radiation and annual precipitation.In present study, we measured leaf litter decomposition of ten common species(Thermopsis lanceolata, Polygonum viviparum, Kobresia capillifolia, Anemone rivularis, Scirpus pumilus, Gentiana straminea, Artemisia sieversiana, Saussurea nigrescens, Elymus nutans and Ligularia virgaurea) in a Tibetan alpine meadow under shading and natural light treatments. We set six replicates per treatment for each of selected species, and litter decomposition lasted for 36 months. The main results were as follows: (1) Litter decompositionShading decreased significantly litter mass loss, while the magnitude depended on species identity; Regardless of shading and exposed to light, litter mass loss correlated with lignin content. (2)The mass loss of litter lignin, cellulose and hemicelluloseShading decreased significantly litter lignin, cellulose and hemicellulose mass loss, with the magnitude depending on litter species. (3)Litter N, P dynamicsLitter N and P had released after 360 days, which were not affected by shading.To sum up, light radiation can increase the C release of litter types, but has no effect on the release of N,P. This study suggests that light radiation promote litter decomposition through accelerating photodegradation of structural carbon compounds in Tibetan alpine meadow.