The Impact Assessment Of Betula Luminifera Natural Secondary Forest After Tending Management

Betula Luminifera is a precious native tree species in South China,which has higher economic benefit and ecological function of soil improvement and water conservation.Guizhou province has richer natural forest resources,accounting for 70% of the total forest stand area,but the vast majority of forest is secondary forest,and lack of management.In this paper,studying on the existing natural secondary forest of Betula Luminifera in Majiang County,Guizhou province,setting up two kinds of forest tending measures,thinning intensity and controlling mixing ratio,of which tending thinning forest tending measures have 4treatments,the 4 thinning treatments are 37%,21%,10% and 0%;The regulation measures of mixed proportion has 5 treatments,which is according to the number of trees in Betula luminifera and Yungui Carpinus turczninowii,and the ratio of Betula luminifera to Yungui Carpinus turczninowii is 4:1,2:1,1:1,1:4 and pure Betula Luminifera forest,the effects of different treatments on the forest structure,stand growth,undergrowth vegetation diversity and natural regeneration capacity of natural secondary forest of Betula Luminifera under two kinds of tending measures were studied in this paper,to evaluate and select the most suitable tending measures for forest management of natural secondary forests of Betula Luminifera,and to provide some guidance for forest management in secondary forests of other tree species,The main research results are listed as follows:(1)The present study found that two kinds of tending measures can effectively improve the forest structure of Betula Luminifera natural secondary forests,which are shown concretely in the following 4 aspects:(1)After the thinning of 3years,compared with the distribution state of stand diameter of the control group which without thinning,the thinning group have more trees in big DBH class.In the control measures of mixed proportion,the mixed group has more Betula Luminifera and Carpinus pubescens trees in big DBH class than the control group;(2)The study of stand mingling found that,in the measures of tending thinning and control measures of mixed proportion,the standmingling in each treatment group wassignificantly higher than the control group without tending thinning.(3)The study of stand spatial dominance showed that the measures of tending thinning and control measures of mixed proportion could improve the stand spatial dominance,When the thinning intensity was37%,the stand spatial dominance was significantly higher than the control group without tending thinning,and the spatial dominance of the treatment group of mixed proportion control was significantly higher than the pure Betula Luminifera forest.(4)the study of forest layers showed that after thinning,the number of forest layers reached the standard of multi storey,but there was no significant difference from the control group,but the study of the average tree height of storey showed that when the thinning intensity was 37%,the average tree height was significantly higher than the other treatments.(2)Through the study of the effect of two kinds of nurturing measures on the growth of the Betula Luminifera natural secondary forest,it was found that both thinning and mixed proportions could effectively promote the growth of stand,which is manifested in 5 aspects:the average height of stand,the average height of stand,the broken area of stand,the average individual volume of stand,and the accumulation of stand volume,and it was found that in the measures of thinning,the growth effect of the stand was the best when the thinning intensity was 21%~37%,and the annual average growth rate of 37% thinning strength reached 21.697%,which was significantly higher than other treatments.(3)The study of undergrowth vegetation diversity index(richness index,diversity index and evenness index)found that thinning reduced the richness of the herb and had no significant effect on the richness of shrub,but increased the richness of shrub to a certain extent;the study of diversity index and evenness index of undergrowth vegetation showed that thinning could significantly improve the diversity index and evenness of shrub and herb.In the study of the undergrowth vegetation diversity in the mixed proportion control measures,it was found that the values of each index of the undergrowth vegetation diversity of the mixed groups were significantly higher than those of the pure Betula Luminifera forest.(4)The study of natural regeneration after thinning of Betula Luminifera natural secondary forest shows that the tending thinning and mixing ratio can promote the regeneration of undergrowth,in the tending thinning,the arrangement of the number of seedling regenerationwas 37% > 21% > 10% > control;the order of forest window area was 37% > 21% > 10% >control;in the controlling mixing ratio,the arrangement of the number of seedling regeneration was 2:1 > 1:1 > 4:1 > 1:4 > control;The order of forest window area is 4:1 >2:1 > 1:1 > 1:4 > control.(5)The comprehensive evaluation results showed that in the thinning tending,when the thinning intensity was 37%,the management effect was best,in the controlling mixing ratio,when mixed ratio of Betula Luminifera and Yungui Carpinus turczninowii was 2:1,the effect of mixed control was best.