The Indirect Effect Of UV-B Radiation On Decomposition Of Leaf Litter Of Main Tree Species In Subtropical Region

Forest litter plays a key role in maintaining soil fertility, nutrient and carbon recycling inforest ecosystems. The forest litter decomposition and nutrient mineralization is the main way ofmaterial cycle and energy conversion in terrestrial ecosystems, and an important component of theglobal carbon budget. Under the background of global environment change, studying the effect ofUV-B radiation on litter decomposition is important to elucidate the litter turnover,biogeochemical cycle and forest soil nutrient dynamics. In this study, under, the effect ofCunninghamia lanceolata, Schima superba, Cinnamanun camphora, Elaeocarpus sylvestris andCyclobalanopsis glauca is studied under the treatments with elevated UV-B and ambient UV-Bcondition, which are the advantages of tree species of three stages of subtropical forest in Chinaincluding coniferous forest, mixed forest and evergreen broad-leaved. Main results are as follows:Elevated UV-B radiation significantly accelerates the the original K content of C. lanceolataand C. glauca22.1%and22.8%(P <0.001), respectively, and decrease the original N content ofof C. camphora by36.0%(P<0.05).The decomposition of leaf litter of C. lanceolata, exposed to elevated UV-B treatment duringgrowth was slower, C. glauca and E. sylvestris is opposite but did not show significant differencewith that of ambient UV-B treatment (P>0.05). UV-B treatment has no significant effect on thedecomposition of litter of C. superba and C. camphora. Elevated UV-B promotes decompositionof litter of C. glauca and E. sylvestris by28.0%、12.3%Elevated UV-B and ambient UV-B condition make the increasing of N concentration of thedecomposition of five leaves litter and do not significantly influenced the P, K and C releaseduring the C. Lanceolata leaf litter decomposition. The increasing and release of C concentrationof litter of C. Camphora appear alternately. Exposure to elevated UV-B and ambient UV-Bcondition make the P and K release of the decomposition of C. Glauca during1year, which bothP and K release ratio are lower than ambient UV-B. Elevated UV-B strengthens the content oflignin by27.9%.