黑河(额济纳河)下游绿洲生态系统受损与生态保育对策的思考

额济纳绿洲是我国西北干旱区中心的一道生态防线。 2 0世纪后半世纪绿洲生态系统严重受损 ,景观结构急剧恶化 ,黑河的供水量逐年趋于下降 ,由 50年代的 1 2 .2 5亿 M3 下降到 90年代的 7.2 4亿 M3。地下水位也相应地降低 ,土地盐化也在加剧。胡扬与沙枣林面积由3 .45万公顷减少到 2 .2 0万公顷 ,并以老龄林为主。红柳灌丛也减少了 50 % ,并且多已成为稀疏矮化的群落。各种禾草草甸严重退化 ,多已演替成为苦豆子群落。为了维护我国西北的这一生态屏障 ,必须坚持以恢复与保护自然绿洲为主 ,恢复胡杨林、沙枣林及红柳灌丛的覆盖率 ;建立人工草地 ,改善土地覆盖 ,建设自然一人工复合绿洲。在绿洲建设与保育工程中必须保证充分供水 ,调控水盐动态 ,发挥生物一景观多样性的系统耦合效应 ,实现绿洲生态系统健康

The Study of Oasis Ecosystem Damage and Conservation in the lower Reaches of Black River (Erginar River)

Erginar Oasis is an important ecological defense in the central area of the North-west of China. During the late half of the 20 th century, the oasis ecosystem was heavily damaged. The landscape structure was dramatically devastated. The water supply of Erginar river was declining year by year, and which decreased from 1.225 billion cubic meters in the 1950s to 0.724 billion cubic meters in the 1990s. The underground water level lowered correspondingly and land saltization also developed. The distribution area of Populus euphratica and Elaeagnus angustifolia decreased from 34500 hec. to 22000 hec., and the woods were dominated by aged trees. The bushes of Tamalix ramosissima decreased by 50 percents, becoming sparse and short. The meadows were degradated, mostly successing into the community of Sophora alopecuroides. In order to conserve this ecological defense in the North-west part of China, the main approach which should be chosen is to recover and to reserve the oasis, to in crease the coverage rate of the Populus euphratica woods, the Ealeagnus angustifolia woods, and the Tamalix ramosissima bushes. Meanwhile, it is needes to cultivate the artificial meadows, to improve the land coverage, and to construct the natural-artificial oasis. In the constructing and the conserving of the oasis, the water supply should be satisfied, the water-salt dynamics of the soil should be monitored, the coupling effects of biology-landscape diversity should be developed. Thus the health of oasis system can be restored.