不同退化红砂荒漠草地的水分分配格局

研究了内蒙古阿拉善盟不同过牧退化红砂草地的土壤 植物 大气系统的水分分配格局、不同退化草地和主要植物种的水分利用效率 .2 0 0 1年降雨量 12 4 .3mm ,其中试验期 119.4mm .1m深土壤水分结果表明 ,10～ 4 0cm土层受蒸散影响最大 ;由于主要共存种红砂和无芒隐子草根系分布和蒸腾强度不同等 ,含水量在 10～ 2 0cm土层以中度退化区显著低于其它样区 (P <0 .0 5 ) ,而 2 0～ 4 0cm土层以轻度退化区较低 .样地年均蒸发量为 30 .6mm ,红砂种群的年均蒸腾量为 11.9mm .随着草地退化加剧 ,裸地的蒸发量和退化指示种匍根骆驼蓬种群的蒸腾量增加 ,而红砂种群的蒸腾量降低 .与较轻度退化区比 ,中度和重度退化区的水分利用率分别下降了 14 .6 %和 4 6 .1% ,红砂水分利用率分别下降了 37.8%和 73.8% .

Water distribution patterns in different degraded desert grasslands of Reaumuria soongorica

Water distribution pattern and water use-efficiency in soil-plant-atmosphere system for light, medium, and heavy degraded Reaumuria soongorica grasslands were studied in Alashan region of Inner Mongolia. The total precipitation in 2001 was 124.3 mm, of which 119.4 mm occured during experimental period. Soil water content (SWC) in 10-40 cm layer was greatly affected by the evapotranspiration. The SWC in 10-20 cm layer of medium degraded grassland paddock was significantly lower (P < 0.05), and the SWC in 20-40 cm layer of light degraded paddock was lower than that of other paddocks due to different transpiration rate and root distribution depth between the main co-existing plant species of R. soongorica and Cleistogenes soongorica in the paddocks. The annual average bare land evaporation and R. soongorica population transpiration were 30.6 mm and 11.9 mm, respectively. As the grassland further degraded, the bare land evaporation and transpiration through Peganum nigellastrum population, a degradation indicating plant species, increased, while the transpiration of R. soongorica decreased. In addition, the water use-efficiency of the grassland and dominant plant species markedly decreased with the increasing grassland degradation. Compared to the light degraded paddocks, for instance, the water use-efficiency of medium and heavy degraded paddocks were reduced by 14.6% and 46.1% for total biomass production, and by 37.8% and 73.8% for R. soongorica, respectively.