Study On Energy Balance and Evapotranspiration of an Artificial Caragana korshinskii Shrub Land in Ordos Plateau

Abstract

Artificial afforestation has rapidly restored the ecology of the Hobq Desert and the Mu Us Sandy Land.A thorough understanding of the characteristics of water and energy in sand plantations is of great significance for improving the management of existing plantations and the development of plantation construction.In a typical sandy artificial Caragana Korshinskii forest in the Yinkensha Forest Farm of the Ordos Plateau， by use of the Bowen ratio system， meteorological variables such as radiation， humidity， and temperature， and surface soil heat flux were measured from June 2014 to June 2016.Energy flux and evapotranspiration under different weather conditions and different time scales in the area were then systematically analyzed based on the observed variables.The results show that on a daily scale， variations of the net radiation and surface soil heat flux on a sunny day were unimodal， while variations of the sensible heat flux and latent heat flux were multimodal.The sensible heat flux accounted for a large proportion of the net radiation， while the surface soil heat flux accounted for the smallest proportion.Energy fluxes were greatly affected by the weather condition， with sensible heat flux the domination in all weather conditions.On a month scale， the net radiation had a unimodal intra-annual variation， with a monthly average of 37.3 W·m-2.The surface soil heat flux fluctuated greatly， accounting for 7.2% of the net radiation.Variation of the sensible heat flux was basically consistent with the net radiation.The sensible heat flux accounted for most of the net radiation， and the monthly average was 24.5 W·m-2.The latent heat flux fluctuated greatly， and was larger in the growing season than in the non-growing season， with a monthly average of 10.1 W·m-2.The net radiation was mainly transformed into latent heat flux from Novemeber to February of the following year， and was mainly transformed into sensible heat flux in other months.The evapotranspiration was 144.7 mm in the growing season from May to October， and was relatively small， with a value of 55.6 mm， in the non-growing season from November to April of the following year.The total evapotranspiration during the study period was 461.3 mm， accounting for 77.5% of the total precipitation in the same period， and the evapotranspiration in 2015 was 176.8 mm， accounting for 90% of the precipitation.Which inidicate that evapotranspiration was the most important water expenditure item in the sandy plantation ecosystem.

Keywords

• sand plantation
• bowen ratio
• energy flux
• evapotranspiration