The Effect On The Forest Growth And Ecological Characteristics Of Larix Kaempferi Plantation Of Management Models

Larix kaempferi is a deciduous coniferous tree belongs to Pinus family.It is not only an important species for both ecological function and timber use but also an excellent ornamental tree species.However,the growth of the tree species is strongly restricted by the site conditions.Growth rates of Larix kaempferi can be varied in different regions of different environments and/or different site conditions in the same region.This paper takes the Larix kaempferi forest close-to-nature forest management in Wanbao Mountain of Longshan County of Hunan Province as the research target,study on the forest growth characteristic and ecological features of 6 different forest management patterns of Larix kaempferi forest,i.e two close-to-nature models,three traditional management models and one comparable forest without any intervention,and observed the changes of forest productivity and biomass,discussed on the best practice of Larix kaempferi forest management,in order to provide scientific instruction on Larix kaempferi introduction,cultivation and operation theoretical basis for the pure coniferous forest transformation in the middle mountain,high humidity and low temperature region in Hunan Province.The results showed as follows:1,The impact on the forest growth is no obvious since the short observation period after the forest operationAfter the 2.5 a management took place,there were certain differences among 6 forest management models regarding the increment of tree height,DBH and stock volume,but not obvious.The result of increment of tree height from big to small is:close-to-nature model b>traditional model a>close-to-nature a>traditional model c>traditional model b>without any intervention ck;The result of increment of DBH and the volume of individual plants from big to small is:traditional model>close-to-nature model>forest without intervention;The result of stock volume of sample plots from big to small is:traditional model c>traditional model b>forest without intervention ck.>close-to-nature model b>close-to-nature a>traditional model a.2,The close-to-nature models have obvious advantages in increasing the biomass and richness of forest vegetation.With the 6 different management models compared,the shrub biomass in close-to-nature model b is higher than other 5 management models,the difference is significant or extreme significant,means the close-to-nature model b is benefit to the growth of under-layer shrub as well as increasing the biomass;the herbal biomass in traditional model b is higher than other management models,difference is significant or extreme significant compare to traditional model a,close-to-nature model a,close-to-nature model b and the forest without intervention ck.The biomass proportion of shrub and herbs(shrub:herb)are:forest without intervention ck 10.0:1,traditional model a 1.9:1,traditional model b 3.1:1,traditional model c 5.3:1,close-to-nature model a 15.0:1,close-to-nature model b 57.1:1.The traditional management way highly damages the under-layer shrub,but the close-to-nature models are in favour of the maintenance of higher shrub-herb biomass proportion.There was only a small change of herb species in the sample plots before and after the operation,but there was a decrease in the plant species of the shrub layer,and the influence on the community structure is not obvious.3,Different operating models of Larix kaempferi have different influences on the broad-leaved treesThere were no significant differences in the species and number of natural broad-leaved trees before and after the operation,and the species and plant number of the broad-leaved trees were significant or extremely significant after the under-planting in the sample plots which has formed a.rational mix structure with coniferous and broad-leaved trees.4,Have less influence on the main physicochemical properties of soil in the short period of time of different management modelsIn this study,there was no significant difference in the contents of pH value,organic matter,available nitrogen,available phosphorus and available potassium of leaching layer(A layer)and the deposited layer(layer B),means the different management models had not significantly affected the soil nutrient status in short period.To find out when does the significant difference appear need a long-term continuous positioning observation.5,There were significant differences in the light intensity of Larix kaempferi forest sample plots before and after the operations.The forest without intervention(ck)has significant difference with traditional model a,has extremely significant difference with close-to-nature a,has near-to significant difference with close-to-nature b,and has no obvious difference with traditional model b and c;The close-to-nature model a has extremely significant difference with other 5 models;The close-to-nature b has significant difference with close-to-nature a.In conclusion,compare with the traditional tending and thinning models as well as forest without human intervention model,the close-to-nature management models are able to form the mixed coniferous and broad-leaved stand as soon as possible with rational forest structure and high forest biodiversity and is beneficial to realize a stable community structure which has strong resistance to the natural disasters.