| In China, subtropical forest is rare vegetation type and the only oasis in the same latitude over the world. The study of litter dynamics in subtropical forest has important theoretical and practical significance for research nutrient cycle, maintenance mechanism for sustainable productivity and vegetation restoration on natural secondary and plantation forest. There were four subjects for this study that included liquidambar forest, camphor forest, pinus forest and mixed forest with camphor and pinus. We spent a year(September 2009 to September 2010)to systematically studied the amount composition and dynamic change for litter, dynamic change of nutrient concentration and nutrient return, decomposition rate of branch and leaf, etc.The results show that:(1) The total quantity of litter for one year was order by mixed forest (4.30 t·hm-2·a-1), liquidambar forest (3.66 t·hm-2·a-1), pinus forest (3.41 t·hm-2·a-1), and camphor forest (3.26 t·hm-2·a-1). The leaves were the most in various components of the litter. Among them, liquidambar forest was the most (75.84%) and camphor forest was at least (71.09%). The monthly dynamic changes were twin peaks of curve on liquidambar forest, and others were the anomalous types. In liquidambar forest, the amount of leaf litter was the highest in October, and it was in August the following year in camphor forest, but it was in November in mixed forest. The four types of forest have the obviously seasonal rule and the most amount of litter was in autumn that was significantly higher than other seasons. Specific changes for rule of seasonal were:autumn> winter> summer> spring in liquidambar forest; autumn> summer> spring> winter in camphor forest; autumn> summer> winter> spring in pinus forest; autumn> winter> summer> spring in mixed forest.(2) If except C, the Ca had the highest concentration and the Ni had the lowest concentration in the branches of litter (but N was the max in mixed forest); the N had the max concentration in the leaf of litter, the min concentration was Co in liquidambar forest and pinus and was Ni in camphor forest and mixed forest; in the fruit of litter, the Co had the min concentration and N had the max concentration (but K was the most element in camphor forest). The volume of nutrient for return was order by mixed forest with camphor and pinus (1901.02 kg·hm-2·a-1),pinus forest (1530.76 kg·hm-2·a-1), camphor forest (1414.75 kg·hm-2·a-1), and liquidambar forest (1370.82 kg·hm-2·a-1). Among that, the leaf of litter was max and the fruit of litter was min, pinus forest was an exception (the branches of litter was min). Just as nutrient, C had the volume of nutrient for return and N was second.(3) The rate of decomposition for branch and leaf litter is significantly higher than in coniferous forest. The leaf litter was significantly more than the stick litter in every stand. Among the 4 subjects, camphor forest have the maximum (2.4651 t·a-1) decomposition rate of leaf litter while pinus forest have the minimum (0.3378 t·a-1). Arranged in order of size is camphor forest> liquidambar forest> mixed forest> pinus forest. The decomposition rate of branch litter in camphor forest is also the largest (0.9289 t·a-1) and pinus forest is the smallest (0.7409 t·a-1). The order is camphor forest> liquidambar forest> mixed forest> pinus forest. The litter decomposition in camphor forest has significantly accelerated in summer while the others in autumn. |
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