Dynamic Study On The Effect About Thinning Of Larix Principis-rupprechtii Mayr. Plantation In Guandishan

Thinning is one of the important technical measures of forest management,it can effectively improve the stand structure,promote the growth of reserved trees,and total yield increase forest,the forest community plant diversity and soil physical and chemical properties have a significant impact,further affect ecosystem carbon sinks function and nutrients biogeochemical cycle,especially in artificial nature management and emphasizes the forest under the background of multi-function,the effect of thinning measures become more important..But the impact of significant degree,duration,and the subsequent effect between different areas and different forest performance difference is big,there is uncertainty,through a large number of thinning experiment and fixed-point observation,clarify different thinning intensity of forest and forest tree growth,vegetation structure and species diversity,and the dynamic effect of soil properties and sustained period,for sustainable forest management has important theoretical and practical significance.Based on the close emperor mountain forest Longxing forest farm in Larix principis-rupprechtii Mayr.Plantation,through 12.3%to 43.6%range of thinning intensity test 9 years fixed point observation,from the stand growth indicators,undergrowth,soil properties,three aspects of analysis,to reveal different thinning intensity of Larix principis-rupprechtii Mayr.Plantation effect of dynamic and duration.The results show that:(1)The thinning can significantly promote the growth of Larix principis-rupprechtii Mayr.Plantation keep wood,from,DBH growth,the larger the thinning intensity to keep wood DBH growth promoting effect,the greater the keep increasing average diameter at breast height difference of continuous wood;Thinning effect on tree height growth was not significant;Thinning has influence to the stand volume unit of area,sample volume per area and so on in constant narrowing of differences.To 9 years,moderate thinning volume per unit area than control stand.(2)The thinning can significantly change the undergrowth species of Larix principis-rupprechtii Mayr.Plantation,and the thinning intensity into positive correlation,weak degree,moderate sample to show the thinning after 6 year>9 year>3 year>1 year,of severe thinning sample area continues to rise;Thinning of Larix principis-rupprechtii Mayr.Plantation can obviously improve the understory plant diversity,moderate and thinning intensity effect is more significant,from 1 to 6 years with the extension of time after cutting,the undergrowth species and diversity index continues to increase,and nine years after the thinning,present a slight downward trend;Compared with the control forest thinning stands,forests and similarity coefficient of species decreased significantly,and the thinning intensity difference,the greater the total of species and the lower the coefficient of similarity.(3)The thinning significantly reduces the soil bulk density,increase soil porosity,especially has an obvious effect of 0 to 10 cm soil layer.Thinning could improve soil ammonium nitrogen,total nitrogen,organic carbon content,significant difference was found in layers of 0 to 10 cm.Moderate and severe thinning can improve the content of nitrate nitrogen,total phosphorus.Thinning significantly increase the amount of soil microbial biomass carbon and nitrogen,and increase with the increase of thinning intensity.