| In this study,two different types of regeneration communities of harvesting Larix sibirica in the forest area of Burqin Branch in Altai Mountain State Forestry Administration were studied:communityⅠ,a mixed forest with Abies sibirica-L.sibirica-Picea obovata-Betula pendula coniferous and broad-leaved mixed,and communityⅡis L.sibirica-P.obovata-A.sibirica coniferous mixed forest.We analyzed the species composition,diameter structure and natural regeneration characteristics of the stand,meanwhile,the effects of different harvesting intensities on under-story vegetation diversity after 40 a later.In order to provide a theoretical basis for the scientific conservation and management of natural forests in this area,as well as to provide a reference for the conservation and regeneration of Larix sibirica.The result is as follows:(1)The number of L.sibirica in the two types of forest communities decreased significantly,and the stand species composition structure changed,with P.obovata or A.sibirica becoming the dominant tree species after harvesting.The diameter distribution c-values of community II weakly harvested stands ranged from 1 to 3.6,and the stand diameter distribution curve showed an inverse J-shaped distribution.With the increase of cutting intensity,the stand diameter distribution curve shifted to the right,and the number of large-diameter stands in the stand increased significantly,and the peak of stand diameter distribution shifted toward the large-diameter direction.(2)The density of A.sibirica regeneration seedlings in community I could reach 5,133 plant/hm~2after harvesting.Meanwhile,the density of P.obovata regeneration seedlings in community II could reach 3,733palnt/hm~2after harvesting,which showed great natural regeneration.The natural regeneration ability of P.obovata or A.sibirica was stronger than that of L.sibirica at low harvesting intensities of 23%and 36%thinning intensity.However,L.sibirica regenerated well naturally under high harvesting intensity of 68%.(3)Under the four harvesting intensities investigated with 19%,33%,55%,and 62%,the species of under-story herbs and shrubs varied with increasing harvesting intensity,showing a significant increase in sun-loving species and a decrease in shade-tolerant species.At 55%harvesting intensity,new species such as Xinjiang wild pea appeared in the under-story herbaceous plants.However,the diversity of under-story herbs and shrubs did not differ significantly with increasing harvesting intensity,and plant density and cover increased and then decreased with increasing harvesting intensity,reaching a turning point at 55%harvesting intensity.(4)The selective harvesting of a single tree species has changed the original forest structure of the natural forests in Burqin,so that the L.sibirica,which was originally the main dominant species,was gradually replaced by other species after harvesting and became a companion species,and it takes a long time to reach the original state through natural recovery,therefore,in future forest management and management,the dominant position of Siberian larch should be restored from the perspective of the forest ecosystem. |
