Study On Soil And Water Conservation Capacity Of The Major Bushes In Limestone Mountainous Area

In this paper, the function of soil and water conservation of the canopy layer and litter layer and root department layer and soil layer of the four kinds of major bush forests (Cotionus coggygria Scop. forest, Forsythia suspensa Vahl. forest, Spiraea trilobata Linn. forest and Vitex negundo Linn. Forest) in limestone mountain area was analyzed systematically and roundly with the methods of indoor experiments and open country experiments from April to October in 2004. The paper also systematically compared the function of soil and water conservation of the four kinds of bush forests. The results showed by the test research were as follows. 1. About the water-holding capacity of the four kinds of bush forests, that of Forsythia suspensa Vahl. forest canopy layer was the strongest. It was 28.00 t·hm-2. The second was Spiraea trilobata Linn.forest and it was 7.70 t·hm-2. That of Vitex negundo Linn. forest was the weakest.It was only 6.41 t·hm-2. Under the identical condition of outside ambient, the diurnal water consumption of bush in one area unit Forsythia suspensa Vahl. forest was biggest. It was 185.17 t·hm-2. And then it was Vitex negundo Linn. forest. That of Cotionus coggygria Scop. forest was minimum. It was only 25.88 t·hm-2. 2. The litter accumulations of Forsythia suspensa Vahl. forestland was biggest. The second was Cotionus coggygria Scop. forestland. That of Spiraea trilobata Linn. forestland was minimum. In the former half hour of soaking process, water-absorbing speed of each bush forest litter was biggest, it reduced obviously afterwards. After twenty-four hours, the water absorbing speed was near zero. In the former half hour, the water-absorbing speed of litter of Spiraea trilobata Linn. forest was biggest. The second was that of Cotionus coggygria Scop. forest. That of Forsythia suspensa Vahl. forest was minimum.The biggest water-holding concents and the contents of water retained efficiently of litter of Cotionus coggygria Scop. forest were highest. The second was that of Forsythia suspensa Vahl. forest. That of Vitex negundo Linn. forest were minimum. 3. About the root distribution feature, there was thoroughly notable discrepancy between the four kinds of bush forestlands. The root biomass in different soil layers also had certain discrepancy even in each bush forestland. The 0～10 cm soil layer was the thoroughly concentrate distribution layer of root in the four kinds of bush forestland. The different diameyer biomass distribution feature of the four kinds of bush forestlands had thoroughly obvious discrepancy. In Cotionus coggygria Scop. forestland and Spiraea trilobata Linn. forestland and Vitex negundo Linn. forestland, embroider line chrysanthemum forest with yellow Jing Lin Nei, root biomass of diameter <1mm was biggest. In Forsythia suspensa Vahl. forestland, root biomass of diameter ≥5mm was biggest. 4. The soil physical properties of the bush forestlands are better than barren slope obviously. The soil physical properties of 0~20cm soil layer were better than that of 20~40cm soil layer obviously in bush forestlands. Soil physical properties had notable discrepancy in the same layer of different bush forestlands. In 0~20cm soils layer, the soil physical properties of Cotionus coggygria Scop. forestland were best and that of Forsythia suspensa Vahl. forestland took second place. In 20~40cm soils layer, the soil physical proterties of Forsythia suspensa Vahl. forestland were best, and that of Cotionus coggygria Scop. forestland took second place. That of Spiraea trilobata Linn. forestland and Vitex negundo Linn. forestland differed from comparatively in the whole soil layer. 5. The water-holding capacity and permeate ability of the bush forestlands were both obviously higher than that of barren slope. The water-holding capacity of the bush forestlands had close positive correlativity with litter accumulations and soil organic contents and length and biomass of root department. The soil water-holding contents of the four kinds of bush forestlands in rainy season were higher than in dry season. In dry season, the natural soil water-holding contents of the four kinds of bush forestlands in 0~ 20cm soil layer were lower than in 20~40cm soil layer. In rainy season, the natural soil water-holding contents of the 4 kinds of bush forestlands in 0~20 cm soil layer were higher than in 20~40cm soil layer. The sequences of water-holding capacity of the four kinds of bush forestlands in rainy season were: Cotionus coggygria Scop. forestland>Forsythia suspensa Vahl. forestland> Vitex negundo Linn. forestland>Spiraea trilobata Linn. forestland.The sequences of infiltration coefficient of the four kinds of bush forestlands were: Spiraea trilobata Linn. forestland.>Cotionus coggygria Scop. forestland >Forsythia suspensa Vahl. forestland>Vitex negundo Linn. forestland. 6. Contents of the organic matter and the N of quick results of soil in 20 ~40 soil layer of the Cotionus coggygria Scop. forestland were neglectly lower than that of the barren slope. After that, contents of the organic matter and the N of quick results and the P of quick results and the K of the entire soil layer of the four kinds of bush forestlands and were higher than that of the barren slope. The soil nutrient contents of 0~20cm soil layers of the four kinds of bush forestlands were obviously higher than that of 20~40cm soil layers. In 0~20cm soil layers, Cotionus coggygria Scop. forest had best accumulation effect on soil organic matter and the K of quick results and the P of quick results. Vitex negundo Linn. forest had best accumulation effect on the N of quick results. Spiraea trilobata Linn. forest had worst accumulation effect on soil nutrient. In 20~40cm soil layers, Forsythia suspensa Vahl. forest had best accumulation effect on the K of quick results and the N of quick results. The accumulation effect of both Spiraea trilobata Linn. forest and Vitex negundo Linn. forest on the K of quick results were not obvious. For the entire soil layer, the soil nutrient condition of Cotionus coggygria Scop. forestland and Forsythia suspensa Vahl. forestland were better and that of Spiraea trilobata Linn. forestland > Vitex negundo Linn. forestland were comparatively of a sort. 7. The soil erosion resistance capacity of the bush forestland fights aggressivity mainly combinedly affected by root length and soil organic contents, litter accumulation, root department biomass as well as total canopy biomass of forest. The sequences of the strengthen role of soil erosion resistance capacity of the four kinds of bush forestland were Cotionus coggygria Scop. forestland>Forsythia suspensa Vahl. forestland> Vitex negundo Linn. forestland>Spiraea trilobata Linn. forestland. The sequences of the corrode modulus of the four kinds of bush forestland were: Forsythia suspensa Vahl. forestland> Spiraea trilobata Linn. forestland > Vitex negundo Linn. forestland >Cotionus coggygria Scop. forestland. 8. The results of systematical analysis showed that the sequences of water-holding function of the four kinds of bush forest were Cotionus coggygria Scop. forest>Spiraea trilobata Linn. forest >Forsythia suspensa Vahl. forest> Vitex negundo Linn. forest. The sequences of insuring earth function of the four kinds of bush forest were Forsythia suspensa Vahl. forest > Cotionus coggygria Scop. forest >Vitex negundo Linn. forest > Spiraea...