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| Indicatory Function of Soil Moisture of Undergrowth Vegetations in the Robinia pseudoacaciaForests With Different Densities in Semi-arid Region on the Loess Plateaus |
| Liu Chenfeng,YinJing,He Kangning |
| College of soil and water conservation, Beijing Forestry University, 100083, Beijing, China |
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Abstract During months of 510 in 2002, radiation, temperature and soil moisture in the forests, the biodiversity and productivity of undergrowth, and the growth of trees in 9 year old Robinia pseudoacacia forests with 6 densities of 3?330 trees·hm -2 , 2?220 trees·hm -2 , 1?750 trees·hm -2 , 1?330 trees·hm -2 , 1?110?trees·hm -2 and 950 trees·hm -2 , and with the canopy density of 1 0, 1 0, 0 9, 0 8, 0 8, and 0 6 respectively were analyzed comparatively. Research can be used to study the indicatory function of undergrowth vegetations with different stand densities. The results showed that the growing condition of trees and undergrowth with low density is prior to that of high density, particularly soil moisture and radiation have a decreasing trend with the increasing density. It also 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. Accordingly, the species and quantity of undergrowth are gradually reduced with the increase of stand densities. And it will evolve from the mesophyte, Roegneria kamoji and Themeda minor as the typical ones to xerophil, Incarvillea sinensis and Chenopodium glaucum which showed that the growing conditions will vary with different stand densities in forests.
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Received: 08 November 2003
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