Study On Species Diversity Of Natural Secondary Phoebe Bournei Forest And Its Natural Regeneration

Based on typical sample investigation to get datas,plant species composition and its diversity of the natural secondary Phoebe bournei forest were analyzed in Ji'an City.The diffusion coefficient method was used to analyze the spatial distribution of the regeneration layer.In order to clarify the main factors affecting the natural regeneration of Ph(Ph is the acronym for Phoebe bournei)seedlings and salpings,a relationship model about saplings and seedlings important values and environmental factors was established with method of quantitative model I.The results would provide scientific basis for the operating and protecting measures of the natural secondary Ph forest.The main results were as follows:(1)There were 107 plant species which belonged to 45 families and 83 genera,including 55 species of trees,25 species of shrubs,23 species of herbs and 4 species of vines in the natural secondary Ph forest.The tree layer and the regeneration layer were dominated by Ph,while shrub layer took the Maesa japonica as the dominant species and herb layer took the Elatostema stewardii as dominant species.The vertical structure order of four layers about diversity indexes respectively showed that: Margalef richness index performed tree layer> herb layer> regeneration layer> shrub layer;Shannon-Wiener diversity index performed herb layer> tree layer> shrub layer> regeneration layer;Pielou evenness index performed herb layer> shrub layer> tree layer> regeneration layer;Simpson dominance index performed regeneration layer> tree layer> shrub layer> herb layer.Overall natural secondary Ph forest were richness and regeneration layer had obvious dominant species,but distribution was not uniform.(2)The value of Margalef richness index,Shannon-Wiener diversity index,Pielou evenness index,Simpson dominance index were 4.54,1.30,0.37 and 0.55 in regeneration layer,respectively.The Margalef richness index significantly correlated with slope position,slope gradient,humus layer thickness,understory vegetation coverage,canopy density,stand density and average diameter at breast height(P<0.05).The Shannon-Wiener diversity index significantly correlated with slope position,understory vegetation coverage,canopy density,stand density and average diameter at breast height(P<0.05).The Pielou evenness index was significantly correlated with slope position,understory vegetation coverage and average diameter at breast height(P<0.05).The Simpson dominance index was significantly correlated with slope position,understory vegetation coverage,average diameter at breast height and canopy density(P<0.05).(3)The tree density of regeneration layer decreased with the increasing of the height classes and the ground diameter classes.Through fitting the relationship between the ground diameter and height we got that the linear fit result was the best.Therefore the relationship between ground diameter and height showed a linear relationship with the coefficient of determination was 0.7585 and 0.8129,respectively.Overall the spatial distribution pattern was aggregated with the order of Ph> Castanopsis fargesii> Schima superba> Machilus velutinawas.With the increasing of the height,spatial distribution pattern of all the tree saplings and seedlings presented from aggregated distribution to random distribution and spatial distribution pattern of Ph saplings and seedlings presented aggregated distribution—random distribution—aggregated distribution—random distribution.(4)The main elements affecting natural regeneration were density(number of Ph parent tree,canopy density,strains density),slope position,humus layer thickness,slope aspect,understory vegetation coverage,litter layer thickness.Number of Ph parent tree played an important role in natural regeneration of saplings and seedlings,while higher or lower of canopy density and strains density,thicker litter layer,thinner humus layer,higher understory vegetation coverage were not helpful to natural regeneration.Meanwhile natural regeneration of saplings and seedlings were more better in semi-shady slope and lower slope than other slope aspect and slope position.Therefore,guaranteeing at least 200 N?hm-2 of parent tree in the stand and controlling canopy density,understory vegetation coverage,litter layer thickness would be helpful to promote natural regeneration of saplings and seedlings.