Structure Dynamics And Production Of Vegetation In The Processes Of Ecological Restoration In Red Earth Of Lijian Valley

In this paper, five typical communities, herbosa, scrub, needle-leaved forest, needle broad-leaved mixed forest and evergreen broad-leaved forest, in red earth of Lijian Valley are studied as the five serial stage of a whole succession series. We try to find out the law of structure dynamics and production of vegetation in the processes of ecological restoration in red earth of Lijian Valley so that we can use these laws of succession to accelerate the speed of ecological restoration in red earth of Ljian Valley by article measure. The results indicated: At herbosa stage, the vegetation coverage is high of at least 80%, and the dominant population is Gleichenia lineris. For scrub, there are many species and the structure is chaotic: trees and shrubs, evergreen species and deciduous species coexisted. The shrub layer's dominant population is Rhododendron simsii and the herb layer's dominant population is Gleichenia lineris or Miscanthus floridulus. Needle-leaved forest, needle broad-leaved mixed forest and evergreen broad-leaved forest all are secondary forest, which come into being after the zonal evergreen broad-leaved forest of Lijian Valley, From. Castanopsis taiwaniana, was destroyed. Pinus massonniana, Liquidambar taiwaniana, Castanopsis cuspidate and Castanopsis taiwaniana are constructive species, and Daphniphyllum macropodum, Castanopsis neocavaleriei, Sorbus folgneri, Diospyros morrisiana, Camellia oleifera, Castanopsis fissa and so on are similar companion species. With the procession of succession, the species diversity trend to increase, and the order according to the index of species diversity is herbosa﹤scrub﹤needle-leaved forest﹤needle broad-leaved mixed forest ﹤evergreen broad-leaved forest. In the community's vertical structure, the order according to the species diversity index of the5 different stage of succession all are the shrub layer>the tree layer>the herb layer. The mainly constructive species'niche breadth trends to change disciplinary along with the procession of succession of the secondary forest of natural recovery. The intolerant tree species'niche breadth, such as Pinus massonniana, Liquidambar taiwaniana, trend to increase along with the procession of succession. On the contrary, the mesophilous tree species'niche breadth increase with the processing of succession, as well as Castanopsis taiwaniana and Castanopsis cuspidate. It dictates that the intolerant tree species will be replace by the mesophilous tree species gradually and it will make the needle-leaved forest that mostly is composed by intolerant tree species develop to evergreen broad-leaved forest mostly composed by mesophilous tree species. But the mainly constructive species'pattern has different change. The intolerant tree species'pattern, such as Pinus massonniana, represent evenness distribution→contagious distribution→random distribution from needle-leaved forest to needle broad-leaved mixed forest to evergreen broad-leaved forest. And the pattern of mesophilous tree species, as well as Castanopsis taiwaniana and Castanopsis cuspidate, are contagious distribution→high contagious distribution→evenness distribution. At the needle-leaved forest stage, the niche overlap of Pinus massonniana and Liquidambar taiwaniana is highest because both Pinus massonniana and Liquidambar taiwaniana are intolerant tree and have the same demand in habitat. For needle broad-leaved mixed forest stage, the niche overlap of Pinus massonniana and Castanopsis cuspidate is higher than the niche overlap of Pinus massonniana and Castanopsis taiwaniana and the reason probably is that the niche breadth of Castanopsis cuspidate is bigger than the niche breadth of Castanopsis taiwaniana in this stage. It indicates that the more population's niche breadth, the more niche overlap with other populations. At evergreen broad-leaved forest stage, being Pinus massonniana retrogression gradually, the niche overlap of Castanopsis cuspidate and Castanopsis taiwaniana becomes highest which have the same demand in habitat. Along with the procession of succession, the niche overlap of Pinus massonniana and broad-leaved species, such as Castanopsis cuspidate and Castanopsis taiwaniana, firstly increases little by little, and then decreases when it reach the max in needle broad-leaved mixed forest stage and finally it will become 0. The broad-leaved species'niche overlap, as well as Castanopsis cuspidate and Castanopsis taiwaniana, increase gradually from needle broad-leaved mixed forest stage to evergreen broad-leaved forest stage. It shows that the competition for resources becomes stronger and stronger between Castanopsis cuspidate and Castanopsis taiwaniana. The community biomass arranged from smallness to greatness is herbosa﹤scrub ﹤needle-leaved forest ﹤needle broad-leaved mixed forest ﹤evergreen broad-leaved forest. It shows that the community biomass increases gradually along with the procession of succession and more and more dry substance are saved in plant. The order according to the biomass of trunk or branch is evergreen broad-leaved forest﹥needle broad-leaved mixed forest﹥needle-leaved forest. However the biomass of leaf is needle broad-leaved mixed forest﹥evergreen broad-leaved forest﹥needle-leaved forest and the reason is that the changes from the sun leaf which is thick, heavy, ceraceous and corneous to shade leaf which is mitis, tenuis and soft result in the fall of biomass of leaf along with the procession of succession. In all these succession stage, the biomass of trunk all occupies the best part among the community biomass, but the biomass of branch or leaf is relatively little because some branch or leaf will be deciduous or be transform into other substance. The annual increment of community biomass arranged from smallness to greatness is herbosa(0.56)﹤scrub(0.67)﹤needle-leaved forest(2.08)﹤needle broad-leaved mixed fores(t7.61)﹤evergreen broad-leaved forest(13.71). I t shows that the more community biomass is, the more annual increment is higher.