Study On The Structure And Physio-Ecological Characteristics Of Degenerated Bamboo Forest Of Phyllostachys Proecox With Covering Organic Material

The degeneration of Phyllostachys proecox with covering organic material was one of the major problems affecting sustainable development of bamboo industry in the region. In order to analysis the degeneration causes and provide scientific basis for its restoration, based on the evaluation of degradation degree, strand structure of degeneration bamboo forest was compared and analyzed, and on the view of plant population ecology, the photosynthesis ecophysiology was studied. The main results were as follows:1.Analysis by principal component analysis (PCA) three factors which contribution rate was 38.18%, 19.39%, 11.51%respectively can reflect most of the information the degradation of bamboo strand. The bamboo forest covered with organic material can be divided into normal growth, mild degraded , moderately degraded,and severe degradation by the factors comprehensive fraction and cluster analysis,the proportion of degeneration bamboo forest reaches 84.21%.2.The average water content in 1-3 year-old bamboo organ of degeneration bamboo forest decreased. In the degradation forest, culm biomass decreased, and biomass of branch and leaf increased. But Variation of biomass for normal bamboo forest turned out contrary to that of degradation forest. With the degeneration aggravation, the biomass of culm, branch and total biomass first decreased then increased, but leaf biomass decreased, relative biomass for organs and above-ground parts of 1-2a bamboo decreased Among degeneration bamboo forest, no significant differences of total height of bamboo with the same diameter at breast height was found, but with the degeneration aggravation, height under branch significantly increased, and crown length significantly decreased. The leaf area of per dry-weight and the single leaf area increased with the degeneration aggravation, the leaf area index varied in a contrary way.3.With the degeneration aggravation, bamboo rhizomes distribution trend to went upper layer greatly. And the amount of bamboo rhizomes of moderately degraded and severe degradation in 0-20cm upper layer account for 90%. With the degeneration aggravation, total length of rhizome and total amount of rhizome bud decreased obviously. The mean rhizome diameter was severe degeneration> normal bamboo>mild degeneration>moderate bamboo forest. And total length of rhizome and total amount of rhizome bud of one-year rhizome diameter of normal and mild degradation bamboo forest were higher than that of severe degeneration and moderate bamboo forest. Total length of rhizome and total amount of rhizome bud of two-year rhizome in normal bamboo forest was higher than that of degeneration bamboo forest.4. With the degeneration aggravation, chlorophyll content decreased remarkably. within the different degeneration type bamboo forest seasonal variation of mean Pn was autumn> summer > the winter > spring, daily mean Tr was summer > spring > autumn > winter, daily mean WUE was winter > autumn > summer> spring ,Pn variation of most degradation bamboo forest showed bimodal curve, except single peak curve for Pn in autumn of severe degeneration bamboo forest.Among the different degeneration bamboo forest, LCP in different season in the sequence Summer > Autumn > Spring > Winter. LSP and P_max in the sequence Summer >Autumn > Winter > Spring, AQY was Winter > Spring and Autumn > Summer .With degeneration aggravation, Annual mean LCP ,LSP and P_max trend to decline in the overall. The value of annual mean AQY were no significant difference among different degeneration degree forest.5.Total nitrogen content in leaf of different degeneration degree forest were autumn > summer > spring > winter ,and that of normal bamboo forest at spring was higher than that of moderate degeneration and mild degeneration and was approximated to severe degeneration bamboo forest. Total phosphorus content of leaf in the same degeneration bamboo forest was autumn > spring > summer > winter, and annual mean of total phosphorus content of normal and mild degeneration bamboo forest were higher than that of moderate and severe degeneration bamboo forest. Annual mean of ratio of nitrogen to phosphorus of normal, mild, moderate and severe degeneration bamboo forest were 9.67, 8.78, 12.37 and 12.16 respectively, and that of moderate and serve degeneration bamboo forest at summer, autumn and winter were higher than that of mild degeneration and normal bamboo forest. Total potassium content of leaf within the same degradation type was higher at summer, but lower at winter. And total potassium content of normal bamboo forest at spring and summer were higher than that of degeneration bamboo forest.6.Both Pn and Tr had Significant correlation with Ci, Cond, Vpd1, PAR and Tair in Phylloslachys praecor forest covered with organic materials. The main direct effect physiological factors to Pn and Tr were Cond, Ci, Vpd1, Tair.P_max had significant correlation with RH, Tair and total nitrogen, chlb, chl concentration in leaf; LCP with total nitrogen, total potassium and chla/b concentration; LSP with RH, PAR, total potassium concentration; AQY with total nitrogen, chla, chlb and chl concentration. Environmental factors, leaf total potassium and chl concentration were the main effect factors to P_max, and leaf total phosphorus had slight effect.