Variation Characteristics Of Soil Nutrients And Vegetation Biomass And Evaluation Of Ecosystem Health In The East Section Of Wushaoling

Qilian Mountain is an important ecological barrier in northwestern,and the health and safety of its ecosystem has always received extensive attention.This thesis is carrying out the survey of farmland and grassland soil quality and soil CO₂ flux in Wushaoling area in the eastern part of Qilian Mountains,combining remote sensing data and statistical data,and carrying out comprehensive evaluation of Wushaoling regional ecosystem health based on the PSR model.The main conclusions drawn are as follows:（1）Through the investigation and statistical analysis of soil nutrients,the total Soil Organic Carbon（SOC）,Total Nitrogen（TN）,Total Phosphorus（TP）and Total Kalium（TK）content of farmland soil in Wushaoling area are higher than that of grassland soil.More than 80%of farmland soil SOC,TN and TK content meet the second-level standard,and more than 70%of the TP content meets the third-level standard.More than 70%of the grassland soil SOC and TN content meet the second-level standards.This indicates that the soil quality in Wushaoling area is in a good state.（2）Correlation analysis results show that the content of farmland soil SOC,TN and TK are extremely significantly correlated with altitude（P<0.01）,grassland soil SOC and altitude are significantly correlated（P<0.05）,and TN and altitude are extremely significantly correlated（P<0.01）,the results of stoichiometric characteristics show that the coupling of farmland soil C and K at different altitudes is better,and the coupling of N and P is poor;the coupling of grassland soil P and K at different altitudes is better,and the coupling of C and N is poor.（3）Through the statistical analysis of CO₂ measurement data,it is found that the change trend of CO₂ flux in different depth intervals of grassland and farmland soil is basically the same,and the subsurface CO₂ concentration increases continuously with the increase of soil depth.In the 0～-10 cm interval,the CO₂ flux of grassland soil is higher than that of farmland soil.In others depth intervals,the CO₂ flux of farmland soil is higher than that of grassland soil.（4）The inversion analysis of remote sensing data found that biomass and Vegetation Fractional Cover（VFC）showed a clear correlation.During the vegetation growth season from 2000 to 2018,the VFC in the study area showed a trend of increasing year by year,from 56%in 2000 to 61%in 2018,with an annual growth rate of approximately of 0.278%.From 2000 to 2018,the average biomass and total biomass also showed an increasing trend year by year.The average biomass increased from 374.6 g/m² in 2000 to 478.6 g/m² in 2018,and the total biomass increased from2.448 Tg in 2000 to 3.13.Tg in 2018.（5）The comprehensive evaluation results based on the PSR model show that the ecosystem in Wushaoling area from 2000 to 2018 showed high ecological health for 1year,moderate ecological health for 16 years,and low ecological health for 2 years.The ecological health value was from 2000 to 2000.0.522 dropped to 0.518 in 2018,which indicates that the ecosystem in Wushaoling area is still relatively fragile.