Effects Of Seasonal Precipitation Distribution On Plant Community Characteristics In Stipa Breviflora Desert Grassland

Stipa breviflora desert grassland is located in a severe arid climate area with poor water conditions.It is obviously affected by the interannual and seasonal differences of precipitation.The accumulation of biomass on the ground of the group is low and fluctuates greatly.Taking the Stipa Breviflora Desert Grassland in Adge,Siziwang County as the research object,this thesis adopts a single factor random block experimental design to study the changes of dominant species,different functional groups and overall community under different precipitation distribution modes.The purpose is to explore the ecological response process of grassland vegetation to different precipitation distribution in growing season,and reveal the characteristics of plant community in desert grassland ecosystem and the relationship between grassland productivity and precipitation seasonal distribution,It provides theoretical support for the rational utilization and scientific management of grassland resources.The main conclusions of this study are as follows:1.The seasonal distribution of precipitation has an obvious regulatory effect on the population characteristics of dominant species in Stipa breviflora desert grassland.Precipitation concentrated in July significantly improved the population characteristics of Stipa breviflora,Cleistogenes songorica and Neopallasia pectinata,especially Artemisia farreri.Precipitation concentrated in August significantly improved the population characteristics of Stipa breviflora and Cleistogenes songorica.There is no significant effect under other precipitation distribution types.2.The concentration of precipitation in July or August will significantly improve the characteristics of C4 plant community,but only the concentration of precipitation in July will significantly improve the characteristics of C3 plant community.Precipitation concentrated in July is more conducive to the growth of dominant species,but the distribution of different precipitation seasons does not affect the community characteristics of non dominant species.The community characteristics of Gramineae and non Gramineae were significantly improved when the precipitation was concentrated in July or August,and the precipitation concentrated in July was more conducive to the growth of herbs.3.The seasonal distribution of precipitation will not significantly affect the richness and diversity of Stipa breviflora desert grassland plant community,but the precipitation is concentrated in July,and the Pielou evenness index of Stipa breviflora desert grassland plant community decreases significantly.The seasonal distribution of precipitation had a significant effect on the aboveground biomass of Stipa breviflora desert grassland(P <0.05).The aboveground biomass in this area is mainly composed of Stipa breviflora,Cleistogenes songorica and Neopallasia pectinata,accounting for more than 90% of the total biomass.Precipitation mainly concentrated in July can significantly increase the aboveground biomass of the community,with an average increase of more than 47%,and the increased biomass mainly comes from Neopallasia pectinata.Monthly precipitation will significantly affect the height,coverage and aboveground biomass of plant communities,but will not affect the density of plant communities.To sum up,the plant growth of Stipa breviflora desert grassland is significantly affected by the seasonal distribution of precipitation,and the concentration of precipitation significantly improves the productivity of plant communities.The concentration of precipitation in July has a significant positive effect on the plant growth of Stipa breviflora desert grassland,and mainly affects the growth of Neopallasia pectinata.