Distribution Pattern And Influencing Factors Of Woody Plant Richness In Lanzhou Area

With the intensification of climate change and human activities,the level of global biodiversity is gradually declining.As a research hotspot under the background of global climate change,the heterogeneity of biodiversity distribution still needs further research in many fields,especially the vegetation in the plateau transition area is more complex,the vegetation has obvious transition,and its richness pattern is more diverse,more fragile and complex.Therefore,exploring the distribution pattern and influencing factors of woody plants in the plateau transition area is helpful to understand the mechanism of plant coexistence and provide support for plant protection under the background of climate change and human activities.In this paper,Lanzhou,which is located in the plateau transition area,is selected as the research area,and the wild woody plants are taken as the research object.A total of 384 sample points are investigated in the field.The purpose is to explore the distribution pattern of woody plant richness and its influencing factors in Lanzhou by using the methods of variance decomposition and standardized stepwise regression.The main results are as follows:(1)In the vertical pattern,the richness of different taxonomic levels of wild woody plants in Lanzhou showed a consistent change trend with the increase of altitude.The richness and density of families,genera and species showed a single peak pattern with the increase of altitude,and the richness reached the maximum at 2250-2300 m,2150-2200 m and 2000-2050 m respectively.The family density and genus density reached the maximum at 2650-2675 m,and the species density reached the maximum at 2800-2850 m above sea level.The altitude pattern of tree richness,shrub richness and density showed a single peak.The species richness reached the maximum at the altitude of2050-2100 m and 2100-2150 m respectively.The species density reached the maximum at 3100-3150 m and 2800-2850 m respectively.(2)In the horizontal pattern,with the increase of longitude from west to East,the richness and density of woody families,genera and species first decreased and then increased,showing a "V" shape;From south to north,with the increase of latitude,the richness and density of woody plant families,genera and species showed a bimodal pattern.(3)In terms of influencing factors,the selected environmental factors explained 41%,41% and 42% of the variation of family,genus and species richness respectively,and the climatic factors had the strongest ability to explain 17%,20% and 18% respectively.The explanation of density is lower than richness,which is 36%,39% and 40% respectively.The contribution of climate factors is the largest,which is 15%,18% and 20% respectively.The selected environmental factors have low explanations for the variation of species richness of shrubs and trees,only 32% and 28%,and the explanations for species density of shrubs and trees are 30% and 27%.The independent interpretation rate of climate factors is the highest,and the interaction between soil and climate factors also has an important impact.In conclusion,the altitude pattern of wild woody plant richness in Lanzhou is unimodal,the longitude pattern is "V" shape,and the latitude pattern is bimodal.The distribution patterns of different taxonomic levels and life forms are basically the same.In Lanzhou,topographic factors have little effect on the richness pattern of wild woody plants,and climate factors play a major role,but the specific environmental factors affecting the richness pattern are different.The above research results provide important basic data accumulation and scientific and technological support for an in-depth understanding of the distribution pattern and influencing factors of woody plant richness in the plateau transition area,especially in Lanzhou.