Influence Of Precipitation Change On Grassland Community Biology And Ecological Stoichiometry Characteristics In The Loess Hilly Region

The herbaceous community is of great significance to soil and water conservation and ecological restoration.The precipitation change pattern will affect the growth and development of the grassland community and the change of soil nutrients.This study investigates the composition of herbaceous community,the survey of aboveground and underground biomass,and the determination and analysis of the chemometrics characteristics of plant leaves,roots and soil in the indoor community,and explores the influence of the precipitation change pattern on the biological and eco stoichiometric characteristics of grassland community.The main conclusions are as follows:(1)The aboveground biomass,the underground biomass,the Magalef richness index,the Shannon-winener index and the Pielou evenness index were all increased and then decreased with the change of the precipitation gradient.The root shoot ratio decreases with the increase of precipitation,and the change of precipitation has significant influence on the 0-20 cm underground biomass and the species diversity index(except for the Magalef richness index).(2)The annual growth of roots in the 0-60 cm and 0-20 cm communities decreased with the increase of precipitation.The amount of root growth decreases with increasing depth.The growth of roots was mainly concentrated in the surface(0-20 cm)and showed apparent aggregation.The annual turnover rate of different soil layers increased with the increase of precipitation,and the variance analysis showed that the change of precipitation had a significant effect on the annual growth of root system.(3)The content of C and K in leaves increased with the increase of precipitation,and the average value of N/P in leaves was 15.16,indicating that plant growth may be limited by both N and P,and the content of C and N in the root system decreased first and then decreased with the increase of precipitation,and the soil C was fluctuating with the increase of precipitation.The soil C and N in the 0-20 cm soil layer were significantly higher than those in the other two layers,showing the surface cohesion.Variance analysis showed that the change of precipitation had a significant effect on C,K and root C and N,and had a very significant effect on soil C.(4)The distribution of C,N,P and K stoichiometry in the roots,leaves and soil of the communities varied in different degrees under the change of precipitation.For plant organs,the distribution ratio of nutrient elements between leaves and roots is declining,and there is a tendency to aggregate to the root system.The grassland community is mainly reflected in the N element.For plant organs and soil,the distribution of nutrient elements is the main decreasing trend,which is the performance of soil nutrient status improvement and grassland community main.It should be embodied in the C and N elements.