Study On Community Characteristics And Population Pattern Of Several Shrubs And Semi-shrubs In Northern Ningxia

Shrubs and semi-shrubs are the main components of arid vegetation,and they play a vital role in maintaining the biodiversity,ecological service functions and stability of desert ecosystems.This study relies on the“China Desert Major Plant Community Survey" project,through field field survey,combined with low-altitude aerial photography,using species diversity index and point pattern analysis method,species composition and species diversity of several shrubs and semi-shrub communities in Ningxia region.The study on the distribution pattern of dominant populations aims to formulate the digital distribution map of desert plant communities and provide basic data services to provide scientific basis for the protection,utilization and research of plant resources in desert areas of China.The results are as follows:(1)There are 77 species of plants in the study area,belonging to 18 families and 51 genera.The ferns are 1 family,1 genera and 1 species,accounting for 1.30%of the total species.There are 1 species and 1 genera of gymnosperms,accounting for 1.30%of the total species.There are 75 species of 49 genera in 16 families of angiosperms,accounting for 97.40%of the total species.The composition of the fauna is relatively simple,mostly drought-resistant or salt-tolerant plants,such as:Artemisia ordosica,Nitraria sibirica,Salsola passerina.(2)The total coverage and total density of shrubs in Artemisia ordosica-Salix cheilophila community were the largest,and the habitat was fixed sand,which created an environment suitable for the survival of Artemisia ordosica,Salix cheilophila and other sand plants.The total coverage and total density of shrub species in the Nitraria sihirica community were the smallest,indicating that the shrub species had the least biomass.(3)Among the 9 plots,there were 7 plots distributed in the Artemisia ordosica population,accounting for 77.77%of the surveyed communities,and the important values were in the first two,indicating that the oilseed population was widely distributed in the desert areas of Ningxia.Artemisia ordosica is an excellent sand-fixing semi-shrub peculiar to the semi-arid sand area of China.(4)The species diversity of each community is generally low.In addition to the dominance degree,the pearl shrub-red sand community has the highest diversity index,indicating that the community is relatively stable.The generality of Artemisia ordosica community is high,and the dominant species plays an important role in the community,indicating that the community structure is unstable and the species composition is relatively simple.The similarity coefficient of each community is between(0.032-0.429),and the similarity level between communities is low.(5)The populations in the survey area were mainly aggregated,and occasionally distributed randomly and evenly on a small scale.Most of the populations of Artemisia ordosica were subject to aggregate distribution,revealing the lack of environmental resources in the desert areas of Ningxia.Its mother plant is a diffusion center.(6)The populations of Artemisia ordosica and Nitraria sibiri are in a large scale,and they are positively correlated and coexisting in coordination.There were negative correlations between the populations of Artemisia sphaerocephala and Artemisia ordosica,Artemisia ordosica and Salix cheilophila population,and the populations of Salsola pcisserina and Reaumuria songarica in large scales,indicating that they competed fiercely for environmental resources.In the artificial community of Artemisia ordosica,the optimal configuration species is Nitraria sibiri.