Abstract: Light radiation plays an important role in litter decomposition in arid and semiarid ecosystems. Yet, whether light radiation significantly affects litter decomposition in Tibetan alpine meadow remains unclear. 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) abundant in Tibetan alpine meadows under shading and control treatments. The results showed that species differed significantly in litter lignin content, with highest in P. viviparum (29.44%) and lowest in L. virgaurea (4.91%). In general, shading decreased litter mass loss, while the decrease extent depended on species. Litter mass loss significantly negatively correlated with lignin content either in shading or in control treatments. Shading decreased the litter lignin mass loss, and the decrease extent varied with species. This study suggests that light radiation promotes litter decomposition through accelerating photodegration of lignin in Tibetan alpine meadow.

Key words: close-to-natural forest management, fruiting, thinning intensity, Quercus liaotungensis, Huanglong and Qiaoshan mountains, seed characteristics