Dynamic Evolution Of Non-spatial Structure Of Coniferous And Broad-leaved Mixed Forest In Zhejiang Province

In order to grasp the natural development trend of coniferous and broad-leaved mixed forests in Zhejiang Province,reveal the dynamic change laws,carry out precise improvement management of forest quality,and rationally carry out forest spatial layout,the continuous inventory of forest resources in Zhejiang Province from 1999 to 2009 was used as research materials to extract coniferous and broad-leaved mixed forests.Forest sample plot and sample wood data,check and recheck the sample plot.Using statistical principles and methods,statistically analyze the non-spatial structure of tree species,tree species diversity,breast diameter,tree height and volume,as well as the dynamic evolution process and characteristics of forest biomass and productivity,and study forest productivity and non-spatial structure Of relevance.the result shows:（1）The distribution of tree species is normally distributed,and there is an ecological saturation thresholdAccording to statistical analysis,the number of tree species on the coniferous and broad-leaved mixed forest plots has gradually increased,and the overall characteristics conform to the normal distribution.The increase rate of tree species has an inverse relationship with the initial tree species.There is an inverse"J"shaped inverse relationship between the initial number of tree species and the average number of tree species changes in the plot,and an"S"-shaped correlation with the theoretical maximum number of tree species.The correlation models are y=3.481e^-0.06532x,y=21.52/(1+2.212e^-0.1569x).The ecological saturation threshold of the number of coniferous and broad-leaved mixed forests is about20.It takes about 45 years to reach this ecological saturation threshold from the natural growth and development of pure coniferous forests or forests with dominant coniferous species.（2）The proportion of coniferous and broad-leaved tree species develops in the direction of increasing proportion of broad-leaved tree speciesThe main coniferous species are masson pine and Chinese fir,and the broad-leaved species are oaks,Schima superba and other hard broad-leaved species.The proportion of coniferous species gradually decreased from 50%to 37%,and the proportion of coniferous species was 38%in young forests and 46%in mature forests.（3）The diversity of tree species has gradually increased,and the internal growth environment of the forest has evolved in the direction of complexity and diversityThe diversity of tree species increases gradually,and the uniformity decreases gradually.The volume diversity of different age groups increased sequentially.The species diversity and evenness of young and middle-aged forests are higher than those of near-mature and mature forests.（4）The distribution of breast diameter,tree height and volume are approximately normalThe shape of the breast diameter distribution in each period is close to the normal distribution,and the mean value and the peak value of the normal distribution are basically unchanged,maintained at 9cm.The shape of the DBH distribution of different age groups is similar to the normal distribution,and the mean and normal distribution apex values gradually increase,both of which increase by about 2 cm.The tree height distribution in each period approximates the normal distribution,with the mean value and the peak value of the normal distribution showing an upward trend.The tree height distribution of different age groups approximates the normal distribution,and the mean and the peak value of the normal distribution show an upward trend.The distribution of individual plant volume in each period is similar to the left-biased normal distribution,and the mean and normal peak values are basically unchanged,maintained at about 0.037m³.The distribution of individual plant volume in different age groups is similar to the left-biased normal distribution.The mean and normal distribution apex values show an upward trend,with an increase of about 0.032 m³.（5）Forest biomass shows an upward trend,the first phase of productivity is higher than the second phaseBiomass increased in each period,and the first stage of productivity(1.39 t·hm^-2·a^-1)was higher than the second stage(1.15 t·hm^-2·a^-1).The biomass of young forests,middle-aged forests and near-mature forests increased during each period,while the biomass of mature forests decreased.The productivity of young forests increased in all age groups in different periods,while the productivity of middle-aged forests,near-mature forests and mature forests decreased.（6）Productivity is positively correlated with DBH,tree height,volume and proportion of coniferous speciesAccording to the statistical calculation,the chest diameter range is better at[10,12],and the peak is reached at 12 cm.After reaching 12 cm,the increase in productivity is not obvious.The productivity is good when the tree height range is[7,10],and reaches its peak at 9 m.After reaching 12 m,the increase in productivity is not obvious.The productivity is good when the volume range is[0.04,0.07].When it is less than 0.04 m³,productivity is prone to negative values.Productivity is positively correlated with the proportion of coniferous species.When it is greater than 50%,productivity no longer appears negative.The correlation between productivity and DBH,tree height,volume and proportion of coniferous species is as follows:proportion of coniferous species>DBH>volume>tree height.In summary,the number of tree species,tree species composition,tree species diversity,non-spatial structure distribution characteristics,forest biomass and productivity,and the relationship with non-spatial structure characteristics of the coniferous and broad-leaved mixed forest in Zhejiang Province are the management and management of the coniferous and broad-leaved mixed forest in Zhejiang Province.Lin provided theoretical basis and technical support.