| Plant functional trait is a plant trait that can make response to changing in habitat and (or) has a certain influence on ecosystem functions. Plant functional trait is most closely related with biomass, resource acquisition and utilization, and resource use efficiency of plants. It is able to reflect survival strategies of plant adapted to environmental changes. Plant traits are formed in the process of plant itself and the environment adaption. Certain plant traits can objectively reflect the specific performance of its ecosystem functional characteristics. So that it is necessary to study and investigate the problem of ecosystem dynamics through plant functional trait.In this thesis, We selected coniferous forest, mixed coniferous and broad-leaved needle forest that represent three different succession stages in Jinyun Mountain of Chongqing.Leaf dry matter content (LDMC), leaf size (LS), specific leaf area (SLA), leaf carbon concentration (LCC), leaf nitrogen concentration (LNC) and leaf carbon-nitrogen ratio (C:N) of leaves were chosen respectively, moreover average community character value, species average character value and function character of component part a and p were analysized by properties of gradient. Comparison of three succession stages in longitudinal way revealed that leaf functional traits have no difference in three varies succession stages under same climate environment. The main results are as follows:1. In three stages, the average leaf area in coniferous forest to mixed needle and broad-leaved forest succession progress showed a trend of increase and with significant differences in the three kinds of samples.2. In three stages, the specific leaf area of mixed coniferous forest is less than broad-leaved forest, broad-leaved forest is less than the needle and there is significant difference between broad-leaved forest and mixed needle.3. Blade thickness of broad-leaved forest is less than coniferous forest, mixed coniferous forest is less than the needle. Coniferous and broad-leaved forest and mixed needle exists significant differences. 4. Leaf blade strength is greater in mixed forest than the needle broad-leaved forest, broad-leaved forest than coniferous forest. Coniferous and broad-leaved forest and mixed needle exist significant differences.5. Three different succession stages of species per unit weight of leaf carbon content (Cmass) is shown that broad-leaved forest is greater than coniferous forest and coniferous forest is greater than the needle. Unit weight of leaf nitrogen content (Nmass) for coniferous forest is greater than broad-leaved forest and mixed broad-leaved forest is greater than the needle. Changing tendency of carbon, nitrogen content per unit area (Carea, Narea) shows that coniferous forest is significantly higher than the other two forest types, and mixed needle and broad-leaved forest are same. Carbon and nitrogen ratio (C/N) in the three stages of presents gradually increased with succession progress trend.6. No significant change in three succession stage of the base fluorescent value Fo. Maximum fluorescence yield Fm performance that coniferous forest is less than the mixed forest and less than the needle. There was a significant difference between the needle leaf mixed forest, coniferous forest and broad-leaved forest respectively. There was no significant difference between coniferous and broad-leaved forest.Tendency of Photochemical quenching coefficient qP of the coniferous forest is greater than the mixed broad-leaved forest and greater than the needle. There was a significant difference between the coniferous, broad-leaved mixed and the needle respectively. And there was no significant difference between coniferous and broad-leaved forest. There was no significant change of maximum quantum yield Fv/Fm and photochemical reaction of photochemical approaches qNP dissipation parameters in this study.The results show that in the three stages of succession, the coniferous forest, mixed coniferous and broad-leaved forest, species evolve gradually from small and thick leaf tree species to big and thin leaf species. The blade strength also has a tendency to become smaller. The proportion of big leaf evergreen species increase gradually. In the community, plant species increase competition ability of light, nutrients, water and space resources by cutting blade thickness and strength, increased leaf area and reduce the leaf carbon and nitrogen ratio. |
