Study On Leaf Litterfall Production And Nutrient Characteristics Of Six Dominant Species In An Evergreen Broad-leaved Forest In Tiantong

Forest litterfall is the key constructive components in the forest ecosystem. It plays an important role in nutrient cycling and energy flow. Leaf litterfall is considered as the major element of it. The subtropical evergreen broad-leaved forests distribute widely in China. As the zone vegetation in subtropical region in China, they are characterized by high species richness and productivity. It is crucial to study the amount and the nutrient characteristics of leaf litterfall of subtropical evergreen broad-leaved forest.The research is based on the 20 ha dynamic plot of evergreen broad-leaved forest in Tiantong, Zhejiang Province, eastern China. The litterfall was collected from January 2012 to December 2014. We analyzed the temporal and spatial dynamics of leaf litterfall production of six dominant species, i.e., Litsea elongata, Cyclobalanopsis nubium, Lithocarpus harlandii, Choerospondias axillaris, Acer pubinerve and Sassafras tzumu. The influence of spatial elements on the dynamics were analysed as well. We also measured their nitrogen(N) concentration, phosphorus(P) concentrations, nutrient return and nutrient use efficiency of the leaf litter in April, July and November from each litter traps. The main results of the study are as follows:(1) The amount of leaf litterfall of Litsea elongate reached a peak from April to August. The peak of Cyclobalanopsis nubium leaf litterfall production is in April. The peak of Lithocarpus henryi leaf litterfall production occurred in June and July. The leaf litterfall production of Choerospondias axiliaris, Acer pubinerve and Sassafras tzumu reached peak in November.(2) Site conditions may influence the leaf litterfall production in different position. The leaf litterfall production of Choerospondias axiliaris and Acer pubinerve were positive correlated with total phosphorus of soil, while that of Sassafras tzumu and Cyclobalanopsis nubium was negative correlated with total phosphorus of soil. Leaf litterfall production of Litsea elongate was negatively correlated with elevation, while that of Acer pubinerve was positive correlated with it. The amount of leaf litterfall of Cyclobalanopsis nubium positively correlated to soil’s total carbon and negatively correlated to soil’s total nitrogen. All of the leaf litterfall production of the six dominant tree species showed a positive correlation with their basal areas.(3) The N concentrations, P concentrations and N:P of leaf litterfall of the six dominant species were significantly different during seasons. The N concentrations of all the species were highest in July while the P concentrations of each species were lowest in their fall peak. Nutrient returns (both N and P) of all the six dominant species were highest in their fall peak. Their nutrient use efficiency of P were higher than N. The N use efficiency of all species was lowest in July while the P use efficiency of each species was highest in their fall peak.(4) The spatial variations of P concentration of the dominant species,except for Litsea elongate, were similar with that of soil P. The lower soil P concentrations correlated with the higher P use efficiency in the leaf litter. But there were no consistent relationship between N concentrations or use efficiency.