Optimization Simulation Of Natural Secondary Forest Structure In Daxing’an Mountain Based On Different Thinning Intensity

Intermediate cutting is one of the main forest harvesting at present,intermediate thinning can improve forest ecosystems and stand structure,accelerate forest growth,improve forest quality,and increase forest trees’ ability to resist natural disasters and pests,and obtain environmental ecological benefits and social economic benefits.Through the determination of the spatial structure unit of the stand and the selection of the spatial structure parameters of the stand,the analysis of the spatial structure of the stand is the specific way to optimize the spatial structure of the stand.Adjusting the spatial structure can improve the growth environment of the retained wood,the forest health level and stand stability.Finally,forests are sustainably managed.In this study,the natural young and middle-aged forests of Daxing’anling were taken as the research object,and the five spatial structural parameters of mingling degree,uniform angle index,competition index,stand level rate and opening degree were taken as the management index,and the non-spatial structure was used as the constraint.Multiplication division method is used to construct the optimization model of spatial structure of natural larch forest in Daxing’anling.Based on the Monte Carlo random sampling principle,we used R language to compile forest management simulation harvesting procedures,and we performed 5,000 random simulations on each of the four simulated intensities(10%,20%,30%,and 40%).We screen out the optimum harvesting intensity and tending plan for each plot Research indicates:(1)The existing forest diameter structure needs to be adjusted;the forest mingling degree is low and the forest horizontal distribution pattern is randomly distributed;the forest vertical structure is poor;the forest opening degree needs to be improved;the single wood growth nutrient space needs to be optimized;(2)When the spatial structure is the main adjustment target,the optimal harvesting scheme under each simulated harvesting intensity gradient is obtained.At this time,the integral optimization function value of the stands is the highest,and the forest structure is improved overall;(3)The comprehensive optimization objective function value of stands increases with the increase of harvesting intensity,but the optimization degree of each forest structure index value is different.In the optimal harvesting plan,the stand maintains a random distribution state,and the competition status in the stand is improved,the mingling degree is increased,the vertical stratification is more obvious,and the diameter structure is more reasonable.(4)Under the condition of canopy density,the optimal cutting plan obtained by plot simulation was screened,and the optimum harvesting intensity of each forest type was 10%-30%.Among them,the optimum harvesting intensity of larch forest is concentrated in 20%-30%,the optimum harvesting intensity of larch birth mixed forest is concentrated in 10%-20%,and the optimal intensity of birch forest is about 10%.