Chin J Plant Ecol ›› 2014, Vol. 38 ›› Issue (5): 425-439.DOI: 10.3724/SP.J.1258.2014.00039

• Research Articles • Previous Articles     Next Articles

Plant species change and water budget in restored grasslands in Taibus Banner, Inner Mongolia, China

XIONG Yu-Jiu1,2,QIU Guo-Yu3,*(),XIE Fang4   

  1. 1Department of Water Resources and Environment, School of Geography and Planning, Sun Yat-Sen University, Guangzhou 510275, China
    2Key Laboratory of Water Cycle and Water Security in Southern China of Guangdong High Education Institute, Sun Yat-Sen University, Guangzhou 510275, China
    3School of Environment and Energy, Peking University, Shenzhen 518055, China
    4College of Resources Science and Technology, Beijing Normal University, Beijing 100875, China
  • Online:2014-05-01 Published:2014-05-13
  • Contact: QIU Guo-Yu

Abstract:

Aims Water is the most constraining factor for implementing the “Grain for Green” project in arid and semiarid steppe regions of China. Our objective was to determine how vegetation and water budget would change following restoration in semiarid grasslands.
Methods Field experiments were conducted in the Farmland and Grassland Ecosystem Observation Station of Beijing Normal University during the growing seasons between 2008 and 2009 in Taibus Banner, located in a typical agro-pastoral zone in Inner Mongolia, northern China. Vegetation composition was studied in six plots representing the natural grasslands (consisting of three separate plots at three sites) and the restored grasslands with two, four and eight years of history, respectively. Three Bowen ratio towers were set up to collect the local meteorological data and to estimate evapotranspiration in each plot. Soil water content was measured using the gravimetric method and soil evaporation was determined by micro-lysimeters with a volume of 200 cm-3 each.
Important findings In the restored grassland plots, plant community coverage increased but the number of species decreased with time of restoration, and the dominant species were gradually transformed from the annual xeric herbs into perennial xerophytic herbs. Plant transpiration, with maximum values of 4.5 to 5.8 mm·d-1, consumed most of the water in the restored grasslands, and longer the restoration higher the rate of evapotranspiration. Soil water in the restored grassland plots was 0.09 m3·m-3 in average, compared with 0.06 m3·m-3 in the natural grassland plots. The soil water content was found to be greatest at 20 cm depth in the natural grassland plots; whereas it was found to be greatest at 60 cm depth, and decreased with time of restoration, in the restored grassland plots. The water budget was balanced at an annual scale in the restored grassland plots because the evapotranspiration was lower than precipitation, while in the growing season of an extreme dry year when annual precipitation was only 174 mm, the evapotranspiration exceeded the precipitation. In conclusion, our results suggest that restored grasslands are able to use more water for establishing vegetation and increase water use efficiency with time of restoration, but the decreasing trend of soil water content should be paid more attention and monitored more comprehensively.

Key words: ecohydrology, evapotranspiration, semiarid region, soil water, water balance