Research On The Dynamic Of Stand Structure And Growth Of Mixedlarch-Spruce-Fir In Jingouling Forest

The dynamic of stand structure and growth of mixed larch-spruce-fir in Jingouling forest under no interferences within 20 years and the disturbances of different cutting intensities are analyzed based on long time monitoring dara through using forest structure and growth indicators including tree species composition, tree species diversity, diameter structure, tree number and volume structure of diameter classes, diameter class diversity and stand stability, stand average DBH, volume per hectare, growth percentage of DBH and stand volume, periodic annual increment of DBH, stand volume, individual tree diameter and volume.lt can provide theoretical basis for the scientific management of mixed larch-spruce-fir in Jingouling forest. The research indicates that:(1)Under no intrfferences within 20 years, the average annual growth of individual tree diameter and volume concentrate on 0.1-0.5cm-a-1and 0-0.1m3·a-1respectively, stand average DBH andstand volume increase with time.The Freese equation can well describe the relationship between diameter class and the average annual growth of individual tree diameter or volume. Within tree species diversity indices, the Shannon-Weiner, Simpson, Simpson ecological dominance and Pielou evenness indices increase with time. The skewness and kurtosis of diameter decrease with time, but the variation coefficient of diameter increase with time, the average q value of stand DBH firstly increases and then decreases with time. Within diameter class diversity indices, Margalef, Shannon and Simpson increase with time; Gini firstly increases and then decreases with time; Pielou and Simpson evenness decrease with time.(2)The influence degree on diameter distribution and stand stability increase with the increasing of cutting intensity, the intensities of 20% and 35% decrease the discrete degree of diameter and keep and improve the stand stability, the intensity of 40% increases the discrete degree of diameter and decreases stand stability. The decrease amplitude of stand average DBH and volume increase with the increasing cutting intensity. The intensities of 20%and 35% are good for DBH and stand volume sustainable growth and fast recoveryand keep and improve tree species diversity after cutting. Within diameter class diversity indices, Margalef, Shannon and Berger-parker indices decrease and Pielou evenness index increases after cutting, the intensity of 20% has litter influence on diameter class diversity and improvesSimpson and Simpson evenness index, the intensity of 40% improves and Gini indices.From the perspective of sustainable management, the cutting intensity of mixed larch-spruce-fir stand in Jingouling forest should control in a range from 20% to 35%, which can be good for the optimization of stand structure and the sustainable stand growth.