Effect Of Different Stands On Seedlings At The Beginning Of Replanting In Greater Khingan Range Low-quality Forest

The object of this study is the broad leaved mixed low-quality forest in Greater Khingan Range, obtain the soil fertility index data、forest canopy parameters complement of survival rate, growth of the replanted trees through experiment. And describe the differences of different stand density planting system in comprehensive evaluation from different aspects. So as to lay foundation for the further research about the ecological impact on replanting in Greater Khingan Range area.(1) Investigating the planting seedling survival rate, seedling height, ground diameter, growth amount, to explore the seedling growth in different density at the beginning of replanting. The result shows that:With the increasing of the stand density, the survival rate of the replanted trees goes to decreased first and then increased. the ground diameter and seedling biomass increased first and then decreased at the same time. The max survival rate was 75%, when the stand density is 2550tree·hm-2;the biggest growth of ground diameter is 0.9cm, when the stand density is 3460tree·hm-2, The max seedling growth is 6.49cm, when the stand density is 3200tree·hm-2.(2) Selecting canopy structure parameters to analyze the Greater Khingan Range broad leaved mixed low-quality forest transformation in forest at the beginning of replanting, so as to explore the trend of the canopy parameters presents as the stand density increasing, and the effect on the seedling growth. When the Gap Fraction was 13.17%,the Openness was 14.10%, LAI was 2.41, PPFD total under was 2.77 MJorMolm-2·d-1,the survival rate is the highest. When the Gap Fraction was 7.49%,the Openness was 8.11%, LAI was 3.38, PPFD total under was 1.11 MJorMolm-2·d-1,the growth of ground diameter is the highest. When the Gap Fraction was 10.58%,the Openness was 11.28%, LAI was 2.63, PPFD total under wasl.62 MJorMolm·2·d-1,the seedling growth is the highest.(3) By using the Grey Relational Analysis to get the comprehensive evaluation of soil fertility on replanting broad-leaved mixed low-quality forest in Greater Khingan Range. Choose the soil samples of different density stands as the experimental object then do the comprehensive evaluation of soil fertility in different plots of the replanting transformation. And study its effects on the seedling. The study result shows that:the grey correlation of Greater Khingan Range area in early planting broad-leaved low quality forest soil fertility showed first increased and then decreased. The largest grey correlation degree of the soil fertility is 0.732. The soil moisture content, water holding capacity, total porosity, ammonium nitrogen, available K and planting seedling survival rate is positively correlated. When the survival rate is the max, their values refer to 0.739,1.104%.0.666,15.575 mg·kg-1,334.340 mg·kgThe soil moisture content, water holding capacity, total porosity, pH, total nitrogen, total potassium, ammonium nitrogen, effective phosphorus and ground diameter growth are positively correlated, when the ground diameter growth is the best, their values refer to 0.565, 0.844%,0.622,6.180,21.980g·kg-1,7.958g·kg-1,259.180mg·kg-1,146.474 mg·kg-1. The growth quantity and the maximum water holding capacity, total porosity, pH, total nitrogen, total potassium, ammonium nitrogen, effective phosphorus and growth are positively correlated, when the seedling growth is the best, their values refer to 1.271%,0.610,6.12,19.189g·kg-1, 7.032g·kg-1,223.190mg·kg-1,134.695 mg·kg-1.This paper researched the stand density influenced the seedling grow that the beginning of replanting. Laid foundation for the further research about the ecological impact on replanting in Greater Khingan Range areas.