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| Soil Moisture Dynamic of the Robinia pseudoacacia with Different Density in Semiarid Region on the Loess Plateaus |
| Li Shirong,Zhang Weiqiang,He Kangning |
| College of Soil and Water Conservation, Beijing Forestry University, 100083, Beijing, China |
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Abstract The motive rule and annual dynamic of soil moisture were studied based on continuous observing the woodland of Robinia pseudoacacia with different density in two growing seasons from May to October, in 1998 and 1999. The observation was carried out once every 10 days and the depth observed is 2 m. The results showed that difference of soil moisture is just about 2% in the woodland of Robinia pseudoacacia with different densities in spring and it has a decreasing trend with the increasing density. When the stand density is sparse, soil water in deeper layer will rise. It showed the phenomenon of soil desiccation with the density increasing in the woodland of Robinia pseudoacacia like the matured stand of the arid and semiarid regions. With the decreasing of water and the gradual increase of water consumption by individual tree, the conflict of water supply and demand was more pronounced. Soil water in deeper layer may be compensated in the area of 8 m in the woodland of Robinia pseudoacacia from water harvesting. The species and quantity of undergrowth are gradually reduced with the increase of stand densities. And it will change from the mesophyte to xerophil. The biomass, coverage, growth and the moisture capacity of plant in the community could be reduced with the increase of stand densities, too. The results showed that the soil water environment will transform with different stand densities in forest.
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Received: 23 April 2003
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