| The Xilinguole Grassland in Northern China is the largest grassland ecosystem of Inner Mongolia and plays an important role in the local ecosystem. However, grassland desertification and degradation re quite severe in this area.Therefore, analysing the interaction relationship of meteorological elements on soil moisture, grass evapotranspiration and forage yield can provide the scientific basis for improving and perfecting the existing grassland protection technology, and policies and measures for the restoration of degraded.The paper took the banning grazing area and grazing area of the West Ujimqin Balaguer River study region as example,which is a representative area of the Xilinguole Grassland. I has simulated the daily actual evapotranspiration of banning grazing area and grazing area by using the dual crop coefficient model SIMDualKc, simulated the spatial and temporal dynamic in NPP by using the CENTURY model, both of which have good results, and the R2 are 0.68, 0.70,0.78,0.64,0.68,0.98, respectively. On this basis, In addition, I has compared and analysed change rules of grass evapotranspiration and aboveground biomass in banning grazing area and grazing area, analysed effects of meteorological elements on grass evapotranspiration and NPP, also analysed effects of grazing on exhaustion of soil water and grass aboveground biomass. The results show as follows:1. Compared grass evapotranspiration of banning grazing area in 2013 to 2015, the grass evapotranspiration in 2014 and 2015 declined by 1.6% and 10.14% respectively. In grazing area, the grass evapotranspiration in 2015 was less 7.48% than 2014. The grass evapotranspiration of grazing area is higher than grazing area in 2014 and 2015. It’s found that soil evaporation of initial growth season has large difference between banning grazing area and grazing area.2. According to simulation results of CENTURY model, we can know grass aboveground biomass in banning grazing area and grazing area in 2013 to 2015, and the droop rates for both of two areas are very close. Grass aboveground biomass of grazing area is less than the data of banning grazing area during 2013 to 2015, with the declining contents are 104.18g/m2,109.3g/m2,108.08g/m2, respectively, which explained that grazing had important influence on accumulation of grass aboveground biomass.3. The results of sensitivity analysis and correlation analysis showed that grass evapotranspiration, grass transpiration and soil evaporation are sensitive to daily maximum temperature, maximum relative humidity and precipitation, and highly correlated with temperature and solar radiation. In addition, the correlation between NPP and each meteorological element explained that temperature and precipitation had significant influence on NPP. Grass evapotranspiration and NPP had high correlation. Both of grass evapotranspiration and NPP explained that year-to-year changes of meteorological elements and grazing had significant influence on grassland. The deteriorating weather conditions led pastures production to year-to-year derease, and grazing led to loss of the soil water and grassland degradation.4. Compared grass evapotranspiration of banning grazing area and grazing area under the conditions of reducing the precipitation to half the actual values or assuming that the precipitation was reduced by half, the results showed that precipitation had influwen on soil evaporation in both of areas, soil evaporation reduced by above 40%, and decrease rate of grass transpiration and soil evaporation for grazing area less than the data of banning grazing area, which explained that the effect of reducing the precipitation on grazing area less than banning grazing area.5. According to the simulation results of SIMDualKc model and CENTURY model,we can know the grassland water demands is roughly 420.3±20.3mm and NPP is roughly 337.24±59.69g/m2. |
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