Study On Change Of Alpine Garden In Changbai Mountain

Alpine garden on the western and southern slopes of Changbai Mountain are a general term for similar vegetation types.Alpine garden is generally composed of patches of dominant species of single herbs,because of its high distribution altitude,concentrated in early July flowering,early spring flower period is short and concentrated,as a tourist attraction,known as alpine garden.Alpine garden is mainly distributed in the Changbai Mountain coniferous forest belt and subalpine birch forest belt,which are beaded forest gaps in the forest belt of high altitude area.At florescence,all the flowers in the alpine garden are in full bloom at the same time.The color of each patch is the same,and different patches are colorful.The landscape is spectacular against the forest,which is a very characteristic and important tourist landscape of Changbai Mountain.In recent years,the number of flowers in the flowering season of alpine gardens decreased,the number of miscellaneous flowers in patches increased,and the ornamental value decreased.Tourists react strongly to this,believing that it is caused by excessive tourism development and improper protection of the landscape degradation.In this study,it was found that the patch area of herbaceous plants shrank and the number of herbaceous plants declined.Small trees,shrubs of different heights and herbaceous plants with smaller flowers during the different florescence appeared in the patch,resulting in a significant decrease in the number of colorful herbaceous plants.In view of the fact that the forest gap in the high altitude area of Changbai Mountain was formed by the typhoon disturbance in 1986,this paper proposed a hypothesis that the alpine garden change was caused by the natural succession of damaged forest plant communities,and the succession speed was accelerated by global climate change.In order to confirm this hypothesis,this paper uses geographic information technology and field quadrats to study the distribution and change of alpine gardens,plant community succession and environmental factors.The main results are as follows:(1)After being disturbed by hurricane in 1986,the alpine garden formed in the altitude of1100～1800m in Changbai Mountain.In the following year,the alpine garden experienced a succession from the herbaceous stage.In the past 35 years,the herbaceous community in some areas was eroded by shrubs and trees.The area of alpine garden does not change uniformly over time.It changes rapidly in the first ten years,then slowly in less than 20 years,and then it begins to accelerate again.(2)The distribution pattern and variation of alpine gardens were affected by topographic factors,and the area and variation of alpine gardens varied greatly among different elevations,slope direction and slope.Altitude and aspect had great influence on the changes of alpine garden area,while slope had little influence.After the wind disaster,the area of alpine garden in the middle altitude area is larger than that in the lower and high altitude areas.The alpine garden changes early and fast within the altitude of 1100～1300m,and it is the first to withdraw from the alpine garden.Since 1996,the distribution of alpine gardens has moved up to more than the altitude of 1300 m.Since 1996,the area of alpine garden within the altitude of 1300 m to 1600 m has changed rapidly,and the area of alpine gardens within the altitude of 1600 m to 1800 m has changed last.Affected by the typhoon,the alpine gardens were mainly distributed on the northwest-west-southwest and south slope,and the area gradually decreased.In the first ten years after the storm disaster,the change rate of slope direction was the fastest,and then the change rate slowed down.After 2014,the change rate of slope direction increased slightly.Alpine gardens are mainly distributed in the gentle slopes of 0～10°.In the first ten years after the wind disaster,the change rate of alpine garden area decreased with the increase of slope,and the change rate of alpine garden area was the fastest and the shrinkage ratio was the largest within 0～5°.After that,the change rate of each slope area slowed down,and the shrinkage ratio of alpine garden area increased with the increase of slope from 2014 to 2022.(3)Compared with the past,each herbaceous patch in the high altitude alpine garden consisted of a single dominant species,now the herbaceous community has changed,and shrubs and small trees have appeared in some patches.Therefore,the vegetation is in the succession from the herbaceous stage to a more advanced stage.In general,the dominant herbaceous species in alpine garden patches changed from single to diverse with time,and the association between herbaceous species was strengthened.Originally,the importance value of the dominant species of herbs with the same florescence and bright and large flowers decreased,while the herbs with different flowering time,small flowers and not bright colors became the dominant species.There were differences in the degree of vegetation change in alpine garden.The faster the change was,the dominant species and their importance values in the herbaceous layer changed,the average height,coverage and number of plants increased,and the species richness and diversity index in the herbaceous layer decreased.The number of shrub species,average height,average ground diameter,richness and diversity index of dominant species increased.The number of tree species,average height,DBH and plant number increased obviously.The characteristics and succession process of plant community are restricted by topography to some extent,and vegetation changes faster in the middle elevation,south slope and large slope area.(4)In recent years,due to the influence of global warming,the surface temperature in the high altitude area of Changbai Mountain increased and the surface humidity decreased.The topographic factors intensified the change of water and heat in the local area,which may have accelerated the succession rate of alpine gardens in the high altitude area.