DISTRIBUTION DYNAMICS OF ARTEMISIA HALODENDRON ABSORBENT ROOTS IN DIFFERENT KINDS OF SANDY LAND
不同类型沙地上差巴嘎蒿细根的分布状态

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.