Based on secular fixed_site data in the artificial sand_fixing vegetation district at the southeast fringe of the Tengger Desert, the formative characteristics of soil microbiotic crusts and its influences on vegetati...Based on secular fixed_site data in the artificial sand_fixing vegetation district at the southeast fringe of the Tengger Desert, the formative characteristics of soil microbiotic crusts and its influences on vegetation dynamics were analyzed. Once sand barrier and artificial vegetation have stabilized the surface of the sifting sand, could form aeolian deposition crust and then evolve into algae_dominated crust. Such processes result from the interactions of physical effects of atmospheric dust and silt deposition on sand surface, sinking and raindrop impact, and soil microorganism activities. Under the condition of less than 200 mm precipitation, the presence of microbiotic crust changes the soil hydraulic conductivity, alters the temporal and spatial distribution of the limited precipitation in sand layer and leads to the decline of deep_rooted shrubs. The development of microbiotic crust and subsurface soil affects the plant growth and seed rain distribution, as a result, the diversity of plant species gradually tend to become saturated and finally affects the vegetation stability.展开更多
During the last 20 years, land use in Kuwait was remarkably changed in various forms. Such changes resulted in positively constructive, as well as, adversely destructive impacts on the local environment and ecology. I...During the last 20 years, land use in Kuwait was remarkably changed in various forms. Such changes resulted in positively constructive, as well as, adversely destructive impacts on the local environment and ecology. In 1993-1994, a buffer zone of 15 km wide and more than 200 km long was established between Iraq and Kuwait. This allowed the restoration of biodiversity, enhancement of ecological conditions and stabilization of fragile soils. In 1991, long bund walls were constructed along the Saudi-Kuwaiti borders by Saudi Arabia and in 1993-1994, a ground trench was dug along the Iraqi-Kuwaiti borders by Kuwait. Bund walls are piles of excavated soils, 2-3 m high, 3-5 m wide and several tens of kilometers length. Constructing 1 km length of a bund wall required 2,500-3,000 m3 （1,000 m length x 5 m average width x 0.5 m depth） amount of soil, which disturbed a groundcover strip of an average area of 10,000 m2 （1,000 m length x 10 m average width）. Border trenches are ground hollows 2-3 m deep, 3-5 m wide and 220 km long. The amount of excavated soil from digging 1 km long trench ranged from 6,000-8,000 m3. Field work indicated that 1 km long of trench had disturbed a groundcover of an average area of 12,000 m2 （1,000 m length ~ 12 m average width）. Such man-induced land features are closely related to land degradation processes, as they were of adverse environmental impacts on soil, surface hydrologic conditions and natural vegetation. The main objective of this study is to assess the immediate and long term impacts of the introduced land use forms in selected areas in Kuwait, such as Wadi AI Batin （Western part of Kuwait）. To achieve such an objective, intensive field program was designed and implemented and the collected data and available information were analyzed and interpreted.展开更多
文摘Based on secular fixed_site data in the artificial sand_fixing vegetation district at the southeast fringe of the Tengger Desert, the formative characteristics of soil microbiotic crusts and its influences on vegetation dynamics were analyzed. Once sand barrier and artificial vegetation have stabilized the surface of the sifting sand, could form aeolian deposition crust and then evolve into algae_dominated crust. Such processes result from the interactions of physical effects of atmospheric dust and silt deposition on sand surface, sinking and raindrop impact, and soil microorganism activities. Under the condition of less than 200 mm precipitation, the presence of microbiotic crust changes the soil hydraulic conductivity, alters the temporal and spatial distribution of the limited precipitation in sand layer and leads to the decline of deep_rooted shrubs. The development of microbiotic crust and subsurface soil affects the plant growth and seed rain distribution, as a result, the diversity of plant species gradually tend to become saturated and finally affects the vegetation stability.
文摘During the last 20 years, land use in Kuwait was remarkably changed in various forms. Such changes resulted in positively constructive, as well as, adversely destructive impacts on the local environment and ecology. In 1993-1994, a buffer zone of 15 km wide and more than 200 km long was established between Iraq and Kuwait. This allowed the restoration of biodiversity, enhancement of ecological conditions and stabilization of fragile soils. In 1991, long bund walls were constructed along the Saudi-Kuwaiti borders by Saudi Arabia and in 1993-1994, a ground trench was dug along the Iraqi-Kuwaiti borders by Kuwait. Bund walls are piles of excavated soils, 2-3 m high, 3-5 m wide and several tens of kilometers length. Constructing 1 km length of a bund wall required 2,500-3,000 m3 （1,000 m length x 5 m average width x 0.5 m depth） amount of soil, which disturbed a groundcover strip of an average area of 10,000 m2 （1,000 m length x 10 m average width）. Border trenches are ground hollows 2-3 m deep, 3-5 m wide and 220 km long. The amount of excavated soil from digging 1 km long trench ranged from 6,000-8,000 m3. Field work indicated that 1 km long of trench had disturbed a groundcover of an average area of 12,000 m2 （1,000 m length ~ 12 m average width）. Such man-induced land features are closely related to land degradation processes, as they were of adverse environmental impacts on soil, surface hydrologic conditions and natural vegetation. The main objective of this study is to assess the immediate and long term impacts of the introduced land use forms in selected areas in Kuwait, such as Wadi AI Batin （Western part of Kuwait）. To achieve such an objective, intensive field program was designed and implemented and the collected data and available information were analyzed and interpreted.
