The Radial Growth Response Of Larixprincipis-rupprechtii Mayr Secondary Natural Forest To The Thinning And Climatic Factors In Guandishan Mountains

Larix(Larixprincipis-rupprechtii)is the main species of forest in North China warm temperate humid and semi humid climate in mountainous area,and plays an important role in water conservation and soil and water conservation.In order to explore the larch natural forests maximum neighborhood competition radius,explore the impact of different thinning intensity and climatic factors on the growth of larch and explore the suitable scope of natural forest thinning intensity for larch.The object of investigation is naturel larch forest which was thined in 1998 and in XiaoWenshan Forest Farm of Guandishan Forest Bureau(Chai LuGou)and Pangquangou National Nature Reserve(BaDaoGou,ShenWeiGou).I had used the goal tree center circle method at different altitude.The natural secondary forest of larch maximum neighborhood competition radius calculation,fitting the corresponding neighborhood competition index change mode Type;through the investigation has not been thinning plots,mild thinning plots,moderate thinning plots and severe thinning plots,while retaining the wood radial growth,retention of timber volume and biomass,forest volume and biomass,forest,correlation analysis and evaluation on the effect of thinning and crown growth;combining the dendroecology correlation method,analyzed in the years between 1981-2010 larch radial growth and related climatic factors(annual average temperature,annual precipitation,average monthly precipitation,monthly mean temperature,monthly extreme high temperature,extreme minimum temperature,monthly mean temperature anomaly,monthly relative humidity,monthly sunshine time response)the basic conclusions are as follows.Made and results:(1)Larch(DBH is 24-30cm,age is 45-60)maximum neighborhood competition radius is 5.5m;in different neighborhood radius index average competition of larch neighbor relationship index:y =19.86x-1.094(R2 = 0.9832);in different neighborhood radius under the Larch adjacent total competition index logarithmic regression relationship:Y = 9.98361n(x)3.2335(R2 = 0.9638).(2)Thinning can delay the basal area of the average annual growth rate of rapid decline in a certain extent,it has contributed to the rapid growth to extend the basal area of the average annual growth rate of the period.With the increase of thinning intensity,radial growth of Larch strengthened,single tree volume and biomass increased,crown and the number of seedlings under forest increase of Larch,but severe thinning could cause the total stand volume and total biomass decreased significantly.When the thinning intensity is 15%-30%,thining can improve the single tree productivity,promote regeneration,keep the overall stability of forest productivity in blanance and we can receive the best interest from the natural secondary forest of larch.(3)The impact of climate on the growth of larch radial is the result of many factors,including interannual climatic factors(annual precipitation and annual average temperature,)has no significant effect on radial growth of larch,and on occasion in response to climatic factors have obvious seasonal.Radial last summer and spring precipitation is not too much for larch growth,but in the autumn of last year.It could promote the growth of precipitation in summer and autumn,spring and winter temperature in the early,mid year spring late last year by the end of the summer extreme high temperature,extreme temperature increase may contribute to the radial larch growth,and in the summer at the end of last year the radial opposite extreme temperature limit of the growth of larch;late last summer,the air humidity of the growing season high value will limit the radial growth of larch,and higher in autumn The air humidity can promote the growth of long sunshine time in the fall.The radial will limit the growth of larch.Combined with the climatic factors on the characteristics of the ring,a wide ring is affected when more precipitation and high temperature one year before the result of joint action,and narrow rings are affected in less rainfall and by low last year,the annual average temperature is almost irrelevant,and precipitation in autumn and winter than in spring and summer precipitation of wheel width is more obvious.