Impact Of Logging Disturbance On Larix Gmelini Forest In The Northern Slope On Greater Hinggan Mountains

More than 80%of terrestrial ecosystems,including the forest ecosystem,have been influenced by natural disasters,human activities or the combination of both natural and human disturbances.disturbances affect all levels of the forest.For modern human exploration and utilization of the forest,human disturbances are far greater than natural disturbances. Harvesting disturbance is one of the most important human disturbances.Therefore,this paper is focused on the role and effect of harvesting disturbances in forest ecosystem.It is of great significance to provide necessary information and strategy for the protection and rational utilization of forest resources.The subject of this paper is once selective-cutting forest,twice selective-cutting forest and natural forest in Tahe forest bureau,Greater Hinggan Mountains.The impact of harvesting disturbance in the northern slope on Greater Hinggan Mountains forest is studied, including forest structure,species composition,regeneration,stand characteristics of coarse woody debris and soil chemical properties of the three types of forest.The main conclusions are:(1)Impact of harvesting disturbance on forest structure and species composition:The number of climax species Larix gmelini is significantly different for the three forest types. After the selective-cutting,the number of Populus davidiana and Larix gmelini is much greater than that in natural forests,and the proportion of the basal area at chest height after selective-cutting is higher,too.There is much difference in species diversity or heterogeneity for natural and Larix gmelini forest after the cutting.(2)Impact of harvesting disturbances on forest regeneration:Harvesting disturbance affects forest regeneration.Once-selective-cutting forest is much higher than natural forest in the number of individual and species composition of regeneration,and regeneration number of twice-selective-cutting forest is less than once-selective-cutting forest.(3)Impact of harvesting disturbance on the forest stand,coarse woody debris, Harvesting disturbance changed the structure of the forest:the volume decreased significantly after selective-cutting of forests,the proportion of volume of different species changed,the proportion of volume of broad-leaved species increased to a certain degree,while the changing trend of conifer species was opposite.The composition of coarse woody debris after selective-cutting of forests changed,stumps became an important component of coarse woody debris,and the number of coarse woody debris in middle and small class had an absolute proportion.Impact of harvesting disturbance on soil chemical properties:Harvesting interference changed the north slope of in the northern slope on Greater Hinggan Mountains pH value,C content and other nutrient content.With the increase of the times of disturbance,the C: N and C:P ratios of surface soil gradually increased,but C:K ratio decreased gradually.