Study On The Structure Characteristics And Operation Technology Of Larix Gmelinii Forest

Larix gmelinii is the main tree species in the cold temperate forest.The long-term development of Larix gmelinii has formed a unique northern coniferous forest ecological system,which is an important ecological barrier and an important timber tree species in northern China.And the quantitative analysis of growth and development of Larix gmelinii forest structure,and then discussed the forest tending thinning technology to optimize the forest structure,improve forest biological productivity,play the role of forest ecological services is of great significance.In this paper,the natural forest of Larix gmelinii in Daxing'anling was selected as the research object,and five representative forest types were selected,such as Larch Ledum palustre L.forest,Rhododendron dauricum,Larix forest,Grass larch forest,Moss larch forest,Betula fruticosa forest.The structural characteristics of forest stand,the growth law,the adjustment technique of stand structure and the optimization design of tending and thinning of Larix gmelinii.The main conclusions as follows:?1?The number order of the diameter order of five young forest stands of Ledum palustre,Rhododendron dauricum,grass,Betula fruticosa,moss larch are all anti-"J"distribution,In middle age forest,Ledum palustre,Rhododendron dauricum,grasse,Betula fruticosa larch forest have a standard number of trees diameter class is"positively skewed mountain-like"distribution,and the rest showed anti"J"type distribution.In the young forest,Ledum palustre,Rhododendron dauricum larch height was"positive mountain-like"distribution,and the height distribution of the numbergrass larch showed a"negative mountain-like"distribution;in the middle-aged forest,grass and Betula fruticosa,have a standard number of trees height is"J"type distribution,the rest are"positive mountain-like"distribution;In the near-mature and mature forest,the number of trees of Ledum palustre,Rhododendron dauricum,and Betula fruticosa are all anti-"J"distribution,and the grass and mosses larchis"positively skewed mountain-like"distribution.?2?Through the model fitting and screening,the distribution of DBH and tree height of Larix gmelinii larvae were all three-parameter Weibull distribution,the correlation coefficient is above 0.9,The shape parameter b and the scale parameter c are different.?3?The spatial structure of the three types of forest types was analyzed by using the mingling,uniform angle index and neighbourhood comparison of the stand spatial structure parameters.The results showed that the mingling of Larch Ledum palustre forest is 0.190,the uniform angle index is0.549,the neighbourhood comparison is 0.503,the mingling of Rhododendron dauricum Larix forest is0.552,the uniform angle index is 0.505,the neighbourhood comparison is 0.057,the mingling of Betula fruticosa is 0.577,the uniform angle index is 0.550,the neighbourhood comparison is 0.508,respectively.The results showed that the mingling of the two species is 0.503.?4?The DBH,DBH,S-curve curves are fitted to the DBH of five forest types using the commonly used growth model,Logistic,Kampitz,Richard,Sumar,quadratic,exponential distribution,power function,Tree height,volume growth law,good fit,and finally selected the optimal growth model.The growth models of DBH,height and volume of Ledum palustre larch:y=ae^?-be-ct??R²=0.972?,y=ae^?-be-ct??R2=0.993?,y=a/(1+be^-ct)?R2=0.865?;The growth models of DBH,height and volume of Larix gmelinii stand are:y=a(1-e^-bt)^c_?R?2=0.994,y=a(1-e^-bt)^c_?R?2=0.994?y=a(1-e^-bt)^c?R2=0.978?;The growth models of DBH,height and volume of Betula fruticosa-Larix:y=ae^-b/?t+c??R2=0.972??y=a/?1+be-ct??R2=0.962??y=ae^?-be-ct??R2=0.998?;The growth models of DBH,height and volume of Grass Larch:y=a(1-e^-bt)^c?R2=0.997??y=ae^?-be-ct??R2=0.998??y=a/(1+be^-ct)?R2=0.990?;The growth models of DBH,height and volume of Moss Larix gmelinii stand are Larix gmelinii:y=a(1-e^-bt)^c?R2=0.971??y=ae^?-be-ct??R2=0.994??y=a(1-e^-bt)^c?R2=0.996???5?According to the structural characteristics of forest stand,the growth process analys is and the density effect theory,the results showed that thinning can increase the total stand production.The thinning intensities of larch forests are 44%,38%and 33%,respectively,and the interval is 7a,9a,and12a,respectively.At the end of thinning?51a?,DBH of stand is 19.6cm,stand volume is 264.4m³/hm²,DBH of control stand is 16.5cm,stand volume is 246.2m³/hm².The ratio of thinning to total stand management is above 1.6,and thinning accounted for 39%of the total.The results showed that the accumulation of thinning stands is greater than that of the control stand.?6?Establish the linear programming objective function and constraint equation,design"man-machine interactive"tending thinning scheme optimization scheme.Based on the standard survey,the"program solving"option in EXCEL of OFFICE was used to solve the number of thinning trees in different diameter class trees of thinned forest.Combined with the production experience,through human-computer interaction and modification scheme,Preferably,the total stand production at the end of thinning is greatest.Compared with the current tending and thinning design technique,the forest tending thinning scheme can improve the design efficiency by more than 50%and increase the total forest production by more than 10%.