摘要
以甘肃省的民勤绿洲为例 ,选择土壤水分最为亏缺的 7月 ,对白刺 (Nitrariatangutorum)沙包不同迎风面 ,以及绿洲和荒漠交错地带的土壤水分进行了取样分析。结果表明 ,对于白刺沙包而言 ,其上层和深层土壤水分是迎风坡大于背风坡 ,中间层次 (4 0～ 80cm)则刚好相反。在绿洲与荒漠的交错带上 ,灌丛沙包与沙丘间低地水分变化有很大的不同 ,总体而言 ,丘间地水分含量大于灌丛沙包 ,但在距离绿洲 40 6m处 ,二者均出现一个土壤水分的最低值。在丘间地表层 ,水分变化是距离绿洲愈近 ,土壤含水量愈高 ;而深层土壤水分的变化趋势则刚好相反。在灌丛沙包上 ,其土壤水分大多在 1.5 %左右 ,远低于植物的萎蔫系数 ,故不能够满足植物生命活动之需 ;在绿洲至流动沙丘这一环境梯度带 ,其水分变化可以明显划分为 3个区间。基本规律是 ,愈靠近绿洲 ,土壤含水量也愈高 ;而随着与绿洲距离的逐渐拉大 ,其深层含水量增加、各土层之间的含水量差值也在逐步增大。在丘间地与灌丛沙包底部接触处的丘间地上层 ,存在一个 2 0cm厚度的高含水层 ,这一层次为灌丛植物在年内气候干旱期的生命维持提供着重要水源保证。
The soil water content of shrub sand dune of Nitraria tangutorum and takyr among sand dunes between oasis and desert towards various wind directions near Minqin Oasis of Gansu Province was sampled and analyzed in July when the soil water is most deficient. The results indicate that to the Nitraria tangutorum shrub in sand dune, soil water content in the surface layer and the deep layer towards windward is more than that on the leeward; the situation is opposite in the middle layer (40-80 cm). In the surface layer of sand dunes, the soil water content is higher nearer to the oasis, but the trend of soil water content is opposite in the deep layer. There is a great difference of soil water condition between the shrub sand dunes and the takyr soil. In general, the water content in takyr soil is more than that in shrub sand dunes, however, there exist minimal water content in these two areas at a distance of 406 m from the oasis along the gradient from oasis to shift sand dune. In the surface layer of takyr soil, the closer to the oasis, the higher content of soil water, but the varying trend of water content in deep layer is opposite. On areas of shrub sand dunes, soil water content is only 1.5%, a level insufficient for plant growth. Along the gradient zone of ecotone between oasis and desert, 3 zones can be divided clearly by the change of soil water content. Generally, the nearer to the oasis, the higher the soil water content; and with the extending of distance, the soil water content both in the deep layer and among each layers are gradually increased. There is a 20 cm soil layer with high water content in the takyr soil, which is situated under the shrub sand dune. The high soil water content enables the shrub plant to survive a very arid period of every year.
出处
《植物生态学报》
CAS
CSCD
北大核心
2002年第2期203-208,共6页
Chinese Journal of Plant Ecology
基金
国家自然科学基金项目 ( 4 0 0 710 04
39990 490 )
