A Reasearch On Plant Coummunity Diversity Of Peikutso In Tibet

Peiku Tso(lake)is located in the heart of the Everest Nature Reserve,and is the largest lake in Shigatse of Tibet.This thesis aims to conduct a research on plant community diversity in the area to provide theoretical basis for harmonious coexistence of nature protection and human life in this area and some reference for the protection of plateau lakes.This thesis selected the vegetation in the Peiku Tso area as the research object,and adopted the community sampling method and indoor experiments to collect plant and soil data.Using correlation analysis,cluster analysis and sequencing analysis,the species composition,species life form,species flora,interspecific relationship,species distribution,community classification,community diversity,community diversity and environmental factors of pekucuo plant community were analyzed,which provided scientific basis for local vegetation and ecological environment protection.Through the classical sampling method,29 sample plots were set around the lake area to collect plant species inside and outside the sample.According to statistics,134 species belonging to 86 genera and 34 families were found in the quadrat,with relatively few species,mainly Compositae,Gramineae,Leguminosae and Cruciferae,and the dominant family was Composita.There are many dicotyledons and herbs,few shrubs.The species were toleranted of cold,drought and alkali.The flora has obvious temperate characteristics and there are many endemic species in Tibet.The interspecies correlation of 36 species with a frequency of more than 10% had been tested using the three methods of ?2,Pearson correlation coefficient,Spearman rank correlation coefficient.The three methods complement each other,and the comprehensive results are the most accurate and comprehensive.The results showed that there was a significant positive trend between species.Most of the positive associations were not significant.There were 92 pairs of significant positive connection and extremely significant positive connection,9 pairs of extremely significant negative connection.The results reflected stable community structure and poor environment of Peku Tuo.In general,the diversity level of the vegetation community and coverage in Pektuzo was low,there were fewer species in the community.The difference of community diversity is mainly reflected in richness index and diversity index,but evenness index had no obvious change,it reflected the characteristics of the plant community with obvious differences in the number and types of vegetation in the Peikuo Lake area,but the species distribution is more even.The dominance index can represent the diversity of Pekucuo plant community.The plant communities in the study area had been divided into 8 clusters by hierarchical clustering and hierarchical division.there were 1Achnatherum splendens(Trin.)Nevski+ Iris loczyi Kanitz,Carex moorcroftii Falc,2ex Boott+Kobresia macrantha Bocklr.+ Glaux maritima L,3Oryzopsis munroi Stapf ex Hook.f.+ Artemisia younghusbandii J.R.Drumm.ex Pamp,4Orinus thoroldii(Stapf ex Hemsl.)Bor,5Stipa purpurea Griseb.+Carex oxyleuca V.Krecz+ Astragalus strictus R.Grah.ex Benth,6Caragana versicolor Benth+Artemisia younghusbandii J.R.Drumm.ex Pamp+ Carex praeclara,Nelmes,7Chenopodium foetidum Schrad+Artemisia younghusbandii J.R.Drumm.ex Pamp.,8Carex angustifructus(Kük.)V.Krecz.+ Astragalus tibetanus Benth.ex Bunge+ Stipa purpurea Griseb.The DCA ranking results confirm the clustering results of TWINSPAN.In the tail part of the lake,the shrub cluster diversity was highest,and that of herb group is lowest while in the south part of the lake.The factors that affect community were altitude,longitude,latitude and slope direction.The main factors affecting the community distribution are spatial environmental factors.Diversity index has different distribution characteristics under different conditions such as cluster type,vegetation type and lake area location.The diversity of shrubs in lake tails was the highest,and the diversity of herbs in the lake head was lower.It was called the Caragana versicolor Benth+Artemisia younghusbandii J.R.Drumm.ex Pamp+ Carex praeclara clusters with the highest diversity index,and Oryzopsis munroi Stapf ex Hook.f.+Artemisia younghusbandii J.R.Drumm.ex Pamp and Orinus thoroldii(Stapf ex Hemsl.)Bor clusters with lowest diversity.Through correlation analysis,the environmental factors that affect community diversity include altitude,longitude,latitude,and aspect,with altitude and aspect being the most important.The richness,diversity,and evenness of communities with higher terrain in Pekucuo was higher than those with lower terrain,and the dominance of the community was lower.The south slope community was richer and more diverse than the north slope community,the west slope community was larger than the east slope community,the dominance of the south slope community was lower than that of the north slope community,and the west slope community was lower than that of the east slope community.The closer to the plant communities in the northwest and north shores of the lake,the higher the richness index and diversity index of the community,the lower the dominance index.The richness of the community on the west side of the lake was higher than that on the east side of the lake.The DCA ranking result was a good confirmation of the clustering result of the ranking method TWINSPAN.The plot from lowland to highland,from the west bank to the east bank of the lake,reflected the change of the type of clusters from desert to grassland.From flat to steep slopes,from the south side to the north side of the lake,reflecting the vegetation changes from meadow-grassland-shrub.In the correlation analysis,only AP had significant effect on evenness index.