黄土高原降水资源特征与林木适宜度研究

Study on the Characteristics of Precipitation Resources and the Afforestation Suitability in the Loess Plateau

黄土高原位于干旱半干旱地区,水资源匮乏,如何根据当地的降水条件来确定适宜的植被类型是生态建设中的一个关键问题。通过对黄土高原68个气象台站1961-2000年逐月降水量的统计,结果表明:黄土高原的降水特征总体表现为年平均降水量区域差异大,由东南部的大于600 mm逐渐递减到西北部的不足200 mm;植物生长期间的降水占全年80%以上,且季节分配不均,表现为春旱、夏多、秋少。依据黄土高原的降水资源特征,从林地水量平衡理论出发,以生长季期间林地的水分收支状况来确定林木的适生程度,并以县为单位对黄土高原的林木适宜性进行分区。结果表明,黄土高原适宜于乔木林和灌木林的区域各占1/4左右。

Located in the arid and semi-arid regions, the Loess Plateau is a fragile region with low precipitation and intensive evaporation. Therefore, water is the most important limiting factor, and how to restore suitable vege-tation in different regions based on the precipitation is a foundation to the ecological conservation and regeneration in the plateau. Based on the 40-year （1961 -2000） climate data observed by 68 meteorological stations in the Loess Plateau, the precipitation characteristics in the plateau are analyzed. The results show that precipitation is distinctly different from the different areas, the average annual precipitation decreases from 600 mm in the south to 200 mm in the north of the plateau ; 80% annual precipitation occurs in plant growing season, so it is drought in spring and autumn but rainy in summer. According to the water forestation suitability is calculated using precipitation and different regions for afforestation are divided by regarding balance of the forest ecosystem in growing season, the afecological water requirement of woodlands. On which four the counties in the Loess Plateau as the units. The results reveal that the area suitable to plant trees is about one quarter of the whole plateau, another one quarter of the plateau are suitable to plant shrubs.