| Cypress forest in Lijiang karst area is a forest formed by artificial measures and an important part of karst mountain greening.However,the plantation has single structure and poor stability,which is prone to serious diseases and insect pests.If the plantation density is too high,the understory vegetation and biodiversity will be reduced after full canopy closure.Natural forest regeneration is an ecological process of forest restoration and reconstruction by using nature.It is an important way for cypress plantation to realize self reproduction.For karst rocky desertification areas,the quality of natural forest regeneration directly affects the effect of vegetation restoration and landscape greening.This paper studies the natural regeneration of cypress plantation in Lijiang karst area,and discusses the relationship between natural regeneration of cypress plantation and stand structure and environmental factors,which is conducive to understand the regeneration obstacles and is of great significance to the protection and sustainable development of karst forest landscape.Taking the cypress plantation in Lijiang karst area of Guilin as the research object,the typical sample plot survey method was adopted to design sample plots in different areas of Lijiang karst area.The community structure,regeneration characteristics,stand factors and environmental factors of cypress forest were investigated on the spot,and the response mechanism of cypress regeneration to stand factors and environmental factors was revealed by using person correlation analysis and multiple stepwise regression model,It is expected to provide theoretical guidance for natural regeneration and landscape sustainable development of cypress plantation in karst area of Lijiang River Basin.The main results are as follows::(1)186 species belonging to 162 genera and 77 families were recorded in cypress plantation in Lijiang karst area.The forest community was dominated by arbor and shrub plants,followed by herbaceous plants.Some cypress plantations have native tree species such as Sapium sebiferum,berry neem and South sour jujube,that is,the cypress plantation has a trend of gradual transformation to mixed forest.(2)There are many kinds of local regeneration seedlings in cypress plantation.The survey found that there are 37 species of natural regeneration trees and shrubs belonging to 34 genera in 23 families in cypress plantation.Cypress regeneration seedlings occupy the main position,but the frequency is not high.It can be regenerated naturally only in some sample plots,and the density and height distribution of cypress regeneration seedlings are uneven.(3)Among stand factors,there was a significant positive correlation between moss coverage and the number of regeneration seedlings;Among the environmental factors,soil stone content,slope direction and forest gap area had a significant positive correlation with the number of cypress regeneration seedlings.The results of multiple stepwise regression showed that moss coverage,soil stone content and slope direction were the main reasons for cypress regeneration.Moss coverage,soil stone content,slope direction and forest gap area interact to jointly affect cypress regeneration.(4)By analyzing the obstacles of natural regeneration of cypress plantation in karst area of Lijiang River Basin,this paper puts forward the strategies of sustainable development of cypress community landscape: retaining appropriate forest gap space and cutting off excess rattan irrigation to promote natural regeneration of cypress plantation;Protect and replant native tree species and promote the near natural transformation of cypress plantation;Improve the community structure of cypress plantation and form a multi-level plant community of arbor shrub vine herb;Strengthen ecosystem service functions,etc. |
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