Characteristics Of Eco-hydrology In Meadow Grassland With Different Grazing Systems

The Hunlun Buir grassland is one of the largest natural grassland around the world,But the problem have bothering the harmonious development of the grassland ecological environment between the water,vegetation and cattle in recent years.In our research,we treat different grazing grassland as the research object,then,the rainfall simulation experiment,soil evaporation experiment and soil water infiltration experiments were carry out in the field.Based on these experimental we explore the effects of the different grazing system on the features of eco-hydrology,such as soil evaporation,soil water infiltration,Vegetation canopy interception,soil and water loss.Our research provides the basis for the sustainable development of grassland resources.The main contents were as follow:(1)The characteristic of physical,chemistry,biology have significant(P<0.05)difference in 0-80cm soil depth.There are no obvious regularity of soil physical property in different grazing grassland.There are big differences in the content of soil nitrogen,soil phosphorus,soil potassium,and the rule of it are increase with the soil depth increased.The activity of degradation degree is almost the same trend of polyphenol oxidase,sucrase and urease in 0-80cm soil depth,and the rule of it are decrease with the soil depth increased.The activity of three enzymes of different grazing grassland were Free gazing>Rotation grazing>No grazing.(2)The rotation of soil infiltration were No grazing>Rotation grazing>Free gazing,and the pressure infiltration rate is higher than the pressureless infiltration rate.The relationship of pressure infiltration and pressureless infiltration were fitting with power function.We use the Horton model,Philip model and Kostiakov model to simulation the process of soil infiltration in different grazing grassland.All of three model,the Horton model was simulated best.The soil evaporation of No grazing grassland was 0.884mm/day,Rotation grazing grassland was 0.817 mm/day,Free grazing grassland was 0.794 mm/day.The highest correlation coefficient was 0.503-0.558 between soil water and soil evaporation.The soil evaporation calculated values with measures values had the basic trend of three grazing grassland by reference crop model.The correlation coefficients was 0.95 and the nash-sutcliffe coefficient was 0.76 for Free gazing grassland.The correlation coefficients was 0.92 and the nash-sutcliffe coefficient was 0.71 for Rotation gazing grassland.The correlation coefficients was 0.91 and the nash-sutcliffe coefficient was 0.63 for No gazing grassland.(3)The vegetation interceptions estimated by the water soakage method for No grazing,Rotation grazing and Free grazing grasslands were 0.675mm,0.413mm,0.287mm,respectively.Those estimated by rainfall simulation method were 1.110mm,0.734mm,0.497mm,respectively.The relativity of the interception of the overall vegetation were better with vegetation coverage,leaf area,rainfall.The relationship between interception and rainfall was logarithmic relation,and parabolic relation with rainfall intensity.We build the non-linear regression model between interception and vegetation cover,plant height,biomass,leaf area index,and the correlation coefficients was 0.89 of non-linear regression model.We improvement the Wang yanhui model based on the nonlinear regression model,the improved model had a better simulation effect,and the correlation coefficients of 0.9 above.(4)The runoff and sediment under different rainfall intensities in three grazing grassland were Free gazing>Rotation grazing>No grazing.Rainfall intensity have a significant influence on sediment in runoff,the total sediment and the proportion of clay and silt in sediment were increased with higher rainfall intensity.The nitrogen loss was most in Free grazing grassland,and Rotation grazing grassland was second,and No grazing grassland was least.The phosphorus loss was most in Free grazing grassland,and No grazing grassland was second,and Rotation grazing grassland was least.We used the effective mixing depth model to simulate the process of nitrogen and phosphorus loss from soil.The incomplete mixing model fits the experimental data better than the complete mixing model.The simulation precision was less than 5%in nitrogen loss,and the simulation precision was less than 10%in phosphorus loss.(5)We based on the characteristics of soil physical,chemical and biological to evaluation of grassland health,the No grazing grassland was health,the Rotation grazing grassland was sub-health,the Free grazing grassland was ill health.We based on the characteristics of grassland eco-hydrology to evaluation of grassland health,the No grazing grassland and Rotation grazing grassland was health,the Free grazing grassland was ill health.