Modes And Evaluation Of Ecological Harvesting In Larch Plantation Areas

Currently,the forestry operation is changing from cutting natural forest to cutting plantation forests dominantly.Due to the changeable operation conditions,the dispersed operation objects,the large operation areas,the heavy operation workloads,and the great wastage of work and machines transfer,it is urgent needed to study the cutting modes and evaluation system for plantation forest cutting on suitable environment conditions,such as the forest site configuration,terrain,slope,season and operation space.According to the current situation of larch plantation resources,based on the skidding experiments in larch plantations of Dailing forest bureau,the study first time compared the skidding operation efficiencies and costs under various operation modes.On the flat terrain,the highest skidding operation efficiency is from J-50 tractor skidding with clear cutting,and sequentially from animal skidding with clear cutting and animal skidding with selective cutting; the lowest skidding cost is from animal skidding with clear cutting,and sequentially from animal skidding with selective cutting and J-50 tractor skidding with clear cutting.The DBH distribution of harvested larch plantation was first time modeled using 3 parameters Wewibull function,and the reliability of the model was up to 92.3%.This model is able to predict DBH distribution of forest stands after cutting,and provide the guide for the directional cultivation and management in the future.The study compared the grey model and the statistical model on forest growth factors,and found that the growth factors of non-cut larch plantation worked well to the grey model,and the growth factors of cut larch plantation worked well to the statistical model.The investigations and the analysis showed that,the damage rate of reserved trees in larch plantation played an increasing trend with the increasing both cutting intensity and stand density.Under the various cutting intensities and stand densities,the cutting damage rate and the skidding damage rate for reserved trees had the similar trend,which was increased first and decreased then.The comparison experiments showed that,all of skidding ways,inclusing the tractor skidding with clear cutting,the animal skidding with clear cutting and the animal skidding with selective cutting,significantly influenced the physical characteristics of surface soil.After cutting operations,the bulk density of surface soil was increased obviously,but the porosity,the water capacity and the water drainage capacity of soil were all decreased.The organic contents were reduced most in clear-cut sites with animal skidding,and sequentially are that in selective-cut sites with animal skidding and clear-cut sites tractor skidding. The multi-objects decision method was employed first time to integrate the economy index and the environment index,for evaluating synthetically the objects of cutting/skidding operation ways in larch plantation.It was found that the selective cutting with animal skidding is the optimal operation mode.This operation mode is in accord with the current operation situation in larch plantation of less cutting mission and dispersed cutting sites,and can be used for reference by the other similar larch plantations.The study established first time the evaluation models of ecological cutting for larch plantation,and raised the particular method of index measuring.This application of evaluation model will be able to improve the moderate forest cutting,which does not only satisfy the society demands on timber,but also bring the ecological benefits and social benefits.The study results have the great significances for forest regeneration,growth,stand quality, productivity improvement,ecological cutting efficiency improvement and operation cost decrease in larch plantation,especially are highly valuable to the science and the practice of sustainable economy development in forest areas.