Effects Of Different Management Measures On Ecological Stoichiometric Characteristics In Plants And Soil In Desert Steppe

In order to clarify the response mechanism of C:N:P:K stoichiometric characteristics of plants and soils to different management measures,this study took plant and soil of desert steppe in Yanchi County as the research object.Based on field investigation and laboratory experiments,the variations of C:N:P:K stoichiometric characteristics of plants and soils under different management measures were analyzed,and the correlations between plant and soil C:N:P:K stoichiometric characteristics and soil factors were studied.It is expected to reveal the interactions of C,N,P and K in the desert steppe ecosystem of Yanchi County and its change rules,and provide scientific basis for the adaptive management of desert steppe ecosystem under global change.The main results were as follows:(1)Above-ground biomass and diversity of plant communities were greatly affected by different management measures.The above-ground biomass of grassland conversion for two years was 6.9 times that of grazing grassland.The above-ground biomass of enclosed grassland was 2.3 times that of grazing grassland.The enclosed grassland was 2.3 times that of grazing grassland.The richness index and diversity index of plant communities in grazing grassland were significantly higher than grassland conversion for two years.(2)The community C,N and K content were significantly different under different management measures,while community P content in plant community was slightly different.The community C contents of enclosed grassland and grazing grassland were significantly higher than grassland conversion for two years,the community K content was significantly lower than grassland conversion for two years,and the commnity N content of enclosed grassland was significantly higher than that of grazing grassland and grassland conversion for two years.The community P content of different management measures had no significant difference.(3)C,N,P and K pools of plant communities were significantly different under different management measures.C,N,P and K pools of communities in grassland conversion for two years were significantly higher than those of grazing grassland and enclosed grassland.C,N and P pools of communities in enclosed grassland were significantly higher than those of grazing grassland.(4)Different management measures had greater impact on community C:N,C:K,N:P,N:K,K:P,and less impact on community C:P.The C:N of plant community in grazing grassland was significantly higher than that of grassland conversion for two years and enclosed grassland.The C:K,N:P and N:K of plant community in enclosed grassland were significantly higher than those of grassland conversion for two years and grazing grassland.The K:P of plant community in grassland conversion for two years was significantly higher than that of enclosed grassland and grazing grassland.(5)The contents of organic C,TN and TP in the surface soil of grassland conversion for two years were significantly higher than those of the enclosed grassland,and the contents of TK was significantly higher than those of the grazing grassland.Soil C:P and K:P in enclosed grassland were significantly higher than those of grassland conversion for two years.Soil N:P in grazing grassland was significantly higher than that of grassland conversion for two years.Soil C:N,C:K and N:K in different management measures were not significantly different.(6)Pearson correlation analysis showed that:there were no significant correlations between plant C:N:P stoichiometric characteristics and soil C:N:P:K stoichiometric characteristics.K and K:P of plant community were positively correlated with soil P,negatively correlated with soil N:P.K of plant community was positively correlated with soil K.These showed that plant and soil C,N,P and K were not completely synchronized in the same period.(7)For soil physical properties,the C:N:P:K stoichiometric characteristics of plant and soil were significantly correlated with the content of soil silt,sand and<0.5mm aggregates.For soil chemical properties,the stoichiometric characteristics of plant C:N:P:K were greatly influenced by soil pH,EC,NH4+-N and available P,and the stoichiometric characteristics of soil C:N:P:K were greatly influenced by soil pH and available K.For soil biological properties,the correlations between community C,N,P content and soil enzyme activity were weak,and the correlations between soil C:N:P:K stoichiometric characteristics and soil enzyme activity were strong.