Status Of Ancient Tree Resources And Landscape Evaluation In Nyingchi City

Ancient trees are a bridge to explore the mysteries of nature.The annual rings of ancient trees are a mirror that can show the long-term changes in local climate,hydrology,geology,geography,biology,ecology and other aspects.Ancient trees are green cultural relics and living fossils,a precious resource bestowed by nature upon humanity and an irreplaceable natural resource that possesses economic,scientific and cultural value.The Tibet region has abundant ancient tree resources,but currently,there are only a few studies on the distribution and protection measures of ancient tree resources in certain areas.Therefore,based on a systematic and scientific survey,this paper aims to study the status of ancient tree resources and landscape evaluation in Nyingchi City,with the expectation that this study will provide data support for the archiving,management,protection,and scientific research of ancient trees in Nyingchi City.This study investigates the ancient trees in Nyingchi City at two levels:individual trees and tree communities.In terms of individual ancient trees,the species composition,regional distribution,age structure,growth characteristics and other factors of 400 individual ancient trees in Nyingchi City are analyzed.A detailed analysis is conducted on the three major ancient tree species in the research area:Juglans regia,Prunus mira and Populus szechuanica var.tibetica.Using the grid method,distribution maps of the three major ancient tree species are created and the distribution patterns of Juglans regia,Amygdalus mira and Populus szechuanica var.tibetica in Nyingchi City are analyzed by calculating diffusion coefficients and other indicators.The modified expert program method is used to conduct a landscape evaluation of the individual ancient trees distributed in Nyingchi City.In terms of ancient tree communities,the current status of 37 ancient tree communities in Nyingchi City is analyzed and the most representative 9 ancient tree communities are selected.The scenic beauty estimation(SBE)and the semantic differential(SD)are compared comprehensively to study which important factors affect the public’s value judgment of the landscape in ancient tree communities.Finally,using principal component analysis,the comprehensive score is used as the independent variable and SBE is used as the dependent variable to establish a multiple linear regression model to obtain factors related to the scenic beauty of ancient tree communities in Nyingchi City more intuitively.The results are as follows:(1)There are 400 individual ancient trees in Nyingchi City,belonging to 19 species,14 genera and 9 families.The distribution of ancient trees in different districts and counties of Nyingchi City is uneven,with significant differences.The main species of ancient trees include Juglans regia,Prunus mira,Populus szechuanica var.tibetica,Juniperus tibetica,Quercus aquifolioides,Picea likiangensis var.linzhiensis,Cupressus gigantea,Morus mongolica,Cupressus torulosa and Salix alba.Among them,the main ancient tree species distributed in Bayi district are Juglans regia;Populus szechuanica var.tibetica and Prunus mira;the main ancient tree species distributed in Miling are Juglans regia and Morus mongolica;the main ancient tree species distributed in Pome are Juglans regia;Prunus mira and Cupressus torulosa;the main ancient tree species distributed in Namshan are Prunus mira,Juniperus tibetica and Populus szechuanica var.tibetica;the main ancient tree species distributed in Kongpo Gyamda are Populus szechuanica var.tibetica and Prunus mira;the main ancient tree species distributed in Zayul are Populus szechuanica var.tibetica and Juglans regia.Through the grid method,the distribution pattern of the three major ancient tree species in Nyingchi City was studied and the research results showed that the ancient trees of Juglans regia,Prunus mira and Populus szechuanica var.tibetica were all clustered.(2)In terms of individual ancient tree evaluation,the modified program expert method was used to conduct stratified sampling of 400 ancient trees in Nyingchi City and a sample of 200 trees was selected for landscape evaluation.By calculating the scoring criteria of 6 primary criteria and 22 secondary criteria,the ancient tree with the highest landscape score was a Picea likiangensis var.linzhiensis with a breast diameter of 315 cm,a crown width of16.50×19.40 m and a height of 62.50 m,located in Zha Gong Gou,Nanyi Village,Nan Yi Township,Miling and known as the "Millennium King of Spruces".The ancient tree with the lowest individual landscape score was a Populus szechuanica var.tibetica located in Luo Ma Village,Guyu Township,Zayul,with a total score of only 49.17 points.Overall,the average landscape conversion total score of individual ancient trees in Nyingchi City was 65.59 points,indicating a high landscape value and most ancient trees had good growth and protection conditions.(3)There are 37 ancient tree communities in Nyingchi City,with the most ancient tree communities distributed in Bayi District,with 15 ancient tree communities.The tree species involved in the ancient tree communities that need to be protected in Nyingchi City include Prunus mira,Populus szechuanica var.tibetica,Quercus aquifolioides,Juglans regia,Juniperus tibetica,Buddleja lindleyana,Pinus densata,Cupressus torulosa,Picea likiangensis var.linzhiensis,Malus baccata,Cupressus gigantea,Cerasus duclouxii.(4)In terms of the evaluation of ancient tree communities,firstly,the aesthetic attitude of 61 evaluators was measured using the Scenic Beauty Estimation(SBE)to obtain the scenic beauty value.The results show that the nine ancient tree communities with the highest landscape score in the beauty ranking is the light walnut community in Gala Village,Bahe Town,Kongpo Gyamda,with a score of 0.36;the lowest beauty score is the light walnut community in Laru Village,Bahe Town,Kongpo Gyamda,with a score of-0.47.Secondly,the Semantic Differential(SD)was used and 20 evaluators were selected to quantify the elements of the nine landscapes.When analyzing the SD method,the principal component analysis method was selected to extract one principal component and the comprehensive score was calculated as the independent variable and SBE was used as the dependent variable for multiple linear regression analysis.The equation shows that SBE value is positively correlated with SD value.Among the ten landscape elements,the most important factors that affect the public’s perception of the landscape value of the ancient tree communities in Nyingchi City are the neatness of the branches and leaves and the seasonal changes,while the least important factor is the height of the understory vegetation.