| The construction of the economic forest with ecological and economic benefits is an effective measures to improve the environment and to sharp contradictions between land and people in the Three Gorges Reservoir area. In this study, Bamboo Willow- the fast-growing tree species suitable with riparian zone by preliminary experiment was selected as the research object. The method of space instead of time was used to explore effect of forest age on characteristics and soil quality of riparian ecosystem. Moreover, growth status(1a, 2a, 3a, 4a and 5a) and economic benefits of Bamboo Willow were Studied to explore the afforestation effect and its marketing potential in the Three Gorges Reservoir. The main results and conclusions are as follows:1) Bamboo Willow and contrast on structure and composition of the herb community and biodiversity impact exist significant differences. As the increase of forest age, species richness of contrast is 17, and r two, three and four years bamboo Willow are 23, 28 and 30, The ground herb important value of dominant species are also significant changed In general, the dominant species from light plants( Echinochloacrusgalli and Pouzolziazeylanica) gradually turn into shade plant(Bidenstripartita). With the increase of bamboo willow growth age,Bamboo willow also significantly reduces the herb coverage and biomass gradually,maybe the canopy density of forest increased gradually, at the same time because of the bamboo willow root developed, with nutrient and moisture of interspecific competition advantage, leading to a lower coverage and biomass.2)Bamboo willow forest improved the quality of the soil in the draw-down area. The order of magnitude of moisture content, total porosity, average weight diameter was: four years forest > three years forest > two years forest > contrast. The size of bulk density was: contrast >two years forest > three years forest > four years forest. Both of the bulk density of soils in Bamboo willow forest and contrast ware between 1.1to1.4g?cm-3.Both of the soils contain high organic matter. They ware suitable for the tillage. The bulk density of soil in the contrast was the highest(1.4g?cm-3).Apparently tillage makes soil compaction, permeability, soil water holding capacity and anti erosion ability is weak. The contents of soil organic matter, total N, microbial C and microbial N were as follows: four years forest > three years forest >two years forest >contrast, and the growing age of bamboo willow increased with the trend of increasing. With the increasing of Bamboo willow growing years,Making the root in the soil mosaic distribution wide, increased root density can improve the supply of the soil moisture and nutrient, soil microbial activities to provide rich material and energy supplies. Andtotal P and available P in the soil of contrast was significantly higher than that of bamboo and willow, it caused by the process of traditional planting artificial phosphate fertilization.Therefore, compared with the traditional agricultural planting, the soil and water and fertilizer retention capacity in Bamboo willow forest is better.3)Bamboo willow afforestation effect is good and has great promotion potential Bamboo willow the average survival rate reached to 95.9%, the annual average DBH growth reached to 2.25 cm, base diameter growth reached to 2.93 cm, tree height growth reached to 2.08 m, the crown growth reached to 2.06 m2. Calculated at 5 years, the direct economic value is 15384 yuan per acre, deduct cost and management cost, average annual income is 1226 yuan per acre. Therefore, bamboo Willow not only suitable for keeping with periodic flooding and change of water level, and has significant economic benefits.Bamboo willow changed the composition, structure and biodiversity of herb community, and improved the quality of soil of riparian zone, in the Three Gorges Reservoir. Compared with the traditional agriculture, Bamboo Willow forest by artificial building have a good ability to maintain biodiversity and conservation of water and soil. Moreover, Bamboo willow with water impoundment resistance, the characteristic of fast growth and significant economic value, would be regarded as one of important tree species for the conservation and utilization of riparian zone in the Three Gorges Reservoir. |
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