摘要
以生长于流动沙地和固定沙地上,处于植被演替不同阶段的半灌木差巴嘎蒿(Artemisia halodendron)种群为对象,用土钻取样法研究了生长季(2000年)降雨期前后差巴嘎蒿的根系随土壤深度的分布、生长动态及其与根际土壤含水量的动态关系,观察到:1)降雨期前各土层的根际土壤含水量随深度的增加而升高,增加的幅度为流动沙地>固定沙地;降雨期后根际土壤含水量随深度的增加而减少,减少的幅度为固定沙地>流动沙地。2)表土层(0～15 cm)中差巴嘎蒿的主根分布量在流动沙地显著高于固定沙地。3)降雨期前,差巴嘎蒿细根(直径<1 m/n)分布比例在两种不同类型沙地上的差异表现为:在土层0～45 cm中固定沙地(84.9％)极显著高于流动沙地(61.9％),而在深土层(>45 cm)中流动沙地(38.1％)显著高于固定沙地(22％);降雨期后,不论是在固定沙地还是流动沙地细根多集中于0-15 cm的表土层中,流动沙地的细根分布比例由降雨期前33％增至降雨期后的78％,固定沙地由降雨期前的49％增至降雨期后的63％。表明流动沙地差巴嘎蒿种群细根的生长比固定沙地活跃,能够在生长季降雨期后迅速调整细根的分布比例,使细根分布适应降雨期后浅层土壤含水量高的特点。固定沙地的细根分布难以迅速适应土壤水分的变化,不利于差巴嘎蒿对水分的吸收,成为种群衰退?
Artemisia halodendron an important semi-shrub used for preventing drift-sand and sand storms, degraded significantly in the desert succession series from shifting sandy land to fixed sandy land in the Horqin Sandy Land, hi order to find one of the vital reasons of its degradation, growth and distribution of absorbent roots (fine roots, diameter < 1 mm) of A. halodendron in relation to soil moisture were studied in shifting sandy land and fixed sandy land with trench and root augur methods. Differences between distribution (0-90 cm depth) of its absorbent roots before a raining period and that after the raining period were compared. 1) In the dry season, soil moisture in the rhizosphere increased with depth. It increased much more in shifting sandy land than in fixed sandy land. Soil moisture in the rhizosphere decreased with depth after the raining period. It decreased more rapidly in fixed sandy land than in shifting sandy land. 2) There was more dry weight of main roots in the 0 - 15 cm layer than in the other layers. This phenomenon was more obvious in shifting sandy land than in fixed sandy land. 3)In the dry season, there was a larger proportion of fine roots dry weight in 0 - 45 cm in fixed sandy land (84.9% ) than in shifting sandy land (61.9% ) . In the rainy period, the dry weight of the fine roots of A. halodendron in 0 - 15 cm layer mounted up more rapidly than in the other layers. Furthermore , the fine roots of A. halodendron in shifting sandy land grew more rapidly than the ones in fixed sandy land. The reaction of the fine roots of A. halodendron to precipitation was less sensitive in fixed sandy land than in shifting sandy land, which was a disadvantage of amending of root' s distribution and sucking up of soil moisture.
出处
《植物生态学报》
CAS
CSCD
北大核心
2003年第5期684-689,共6页
Chinese Journal of Plant Ecology
基金
中国科学院奈曼沙漠化研究开放站基金(980121)
内蒙古自治区自然科学基金(20010905-12)
关键词
流动沙地
固定沙地
细根
土壤含水量
植被
Shifting sandy land, Fixed sandy land, Absorbent roots (fine roots), Soil moisture content
