Effects Of Soil Nematode Communities On Litter Decomposition In Urban Forest Of Dalian

In order to further expound the effect of soil nematodes on litter decomposition in urban forest,this study investigated the responses of soil nematodes communities to litter decomposition by litterbags technology at different mesh sizes in Dalian National Forest Park.Soil nematodes community composition,decomposition rate of litter and nutrient release were also analyzed,including moisture content,C content,N content,P content and K content of litter.The nematodes separated from the soil were classified and identified.Results show that a total of 4418 nematodes from 39 genera were found in litter and a total of 5654 nematodes from 40 genera were found in soil.Higher relative density of soil nematodes was found in the bags with 0.1 mm mesh size(1.55 individuals and 7.34 orders per g of dry litter)compared to the bags with 0.02 mm mesh size(0.21 individuals and 0.49 orders per g of dry litter).There were very few soil nematodes in the 0.02 mm litter bags.The soil nematodes quantity and community composition of 0.1 mm mesh size were similar to soil.Thus we regarded that soil nematodes only affected the 0.1 mm litter bags.The decomposition rate of litter showed seasonal dynamics in all mesh size litterbags.The mass loss rates as well as C and P release rates was higher in litter bags with 0.1 mm mesh size than in those with 0.02 mm mesh size,indicating a significant influence of soil nematodes on mass loss and nutrient release.The contribution of soil nematodes to the litter mass loss was about 24%.The effect of soil nematodes on the nutrient release rates differed among elements.The soil nematodes had a bigger influence on the release rate of N than that of other elements,whereas the influence on K release rate was the lowest.There was a significant negative correlation between the relative density of soil nematodes and litter decomposition rate and nutrient residual rate.In such a litter environment,the higher the relative density of soil nematode,the faster the litter decomposition rate,the faster the release of nutrients in litter.The results showed that soil nematodes communities has a significant effect on the litter decomposition and nutrient release of the forest litter in Dalian city,especially promoting the mass loss rates and N release rates.