Dynamics Of Litter Of Four Plant Communities And The Change Of Contents Of Carbon And Nitrogen Of Soil In Hilly Land Area In Central Hainan Island

To study dynamics of litter and changes of the content of carbon and nitrogen of soil in in hilly land area in central Hainan Island, we study litterfall by litter collector and litter decomposition with litterbag by the method of space-for-time substitution in two slope with grass land,shrub land, secondary forest and Acacia mangium plantation. We collected leaf litter in Autumn 2005,from eight sites. Samples of fresh senesced leaves were dried to constant mass, and placed in 15cm×20cm nylon bag, 10g per a litterbag. One hundred and sixty litterbags of each litter type were placed in eight sites in a plat without primay litter remains, and litterbag were be retrieved at 23, 46, 92, 184 and 368 days. After removing roots and soil particles, litter was oven dried (70℃), weighed. At the same time, we sampled soil in every plat when we placed litterbags, and when it went on to the 368th days we sampled soil below the litterbag and that from the control, and analysed the content of carbon and nitrogen of soil.To compare with litter decomposition rates in the same sites is to disccuss litter qualities effect litter decomposition rates; to compare with litter decomposition rates in the different sites is to disscuss environment effect litter decomposition.The main results are following:1. The annual litterfall of grassland is 1.83t/ha, that of shrubland is 3.56t/ha, that of secondary forest is 2.97t/ha, and that of A. mangium plantation is 2.00t/ha.The annual litterfall has not the trend of raise with the progress succession, but there is no significant difference between shrub and secondary forest. The annual litterfall of secondary forest is more than that of A. mangium plantation.2. The proportion of leaf in litter is higher than other components, and doesn't change in dry and rain season.3. The number of species consisting of litter rises with the progress succession, glass landshrub land>grassland, and soil fertilities are improved.The carbon and nitrogen in soil of secondary forest with natural restoration are more than that of A. mangium plantation with manual restoration.