植物生态学报 ›› 2014, Vol. 38 ›› Issue (5): 425-439.DOI: 10.3724/SP.J.1258.2014.00039

• 研究论文 • 上一篇    下一篇

内蒙古太仆寺旗退耕草地植物种类变化与水分收支

熊育久1,2,邱国玉3,*(),谢芳4   

  1. 1中山大学地理科学与规划学院水资源与环境系, 广州 510275
    2中山大学华南地区水循环与水安全广东省普通高校重点实验室, 广州 510275
    3北京大学环境与能源学院, 深圳 518055
    4北京师范大学资源学院, 北京 100875
  • 发布日期:2014-05-13
  • 通讯作者: 邱国玉
  • 基金资助:
    国家自然科学基金(40771037);国家自然科学基金(91025008);国家自然科学基金(41201433);国家重点基础研究发展计划(2009CB421303)

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
  • Published:2014-05-13
  • Contact: QIU Guo-Yu

摘要:

2008年和2009年(均为枯水年), 在半干旱区内蒙古太仆寺旗农田-草地生态系统国家野外站开展观测实验, 通过观测蒸散发(波文比系统)、土壤水分(烘干称重法)、降水量, 以及植被土壤特征调查, 基于水量平衡理论, 对比研究了3块天然草地、3块不同退耕时间草地共6个样地的水分收支, 旨在定量地评估退耕草地的水分收支, 为采取科学措施促进退耕草地尽快向天然草地过渡提供依据。结果表明: 1)随着退耕时间增加, 植被盖度逐渐增加, 但是群落中科、属、种的数量趋于减少, 且优势种从一年生的中旱生草本植物逐渐转变成多年生的旱生草本植物; 2)植被蒸腾是草原植被主要的耗水途径, 随着退耕时间增加, 退耕草地的蒸散发量呈增加趋势, 其最大值在4.5-5.8 mm·d-1之间; 3)退耕草地土壤含水量平均值为0.09 m3·m-3, 其水分剧烈变化主要发生在距地 表60 cm内, 且随退耕时间增加土壤含水量减少, 而天然草地土壤含水量平均值为0.06 m3·m-3, 其水分剧烈变化发生在距地 表20 cm内; 4)随退耕时间增加, 退耕草地与天然草地的土壤水分与蒸散发在数值上差距逐渐缩小; 5)退耕草地水分收支基本平衡, 但在极枯年份(降水量174 mm)的生长季, 降水不能满足蒸散发需求, 呈现水分亏损。退耕草地逐步向天然草地过渡, 但是退耕草地的土壤水分在逐渐减少, 呈现“生境干旱化现象”。今后应加强对草地的封育与监测, 促进植物群落向水分利用效率更高、更适应半干旱环境的方向演替。

关键词: 生态水文, 蒸散发, 半干旱区, 土壤水分, 水量平衡

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