连续干旱对土壤干层深度及植物生存的影响

Impact of the Continuous Drought on the Depth of Dry Soil Layer and on the Existence of Plants

以绥德县为基点 ,分析研究了陕北 1997— 2 0 0 1年连续五年 ,由于降水总量少、有效性差 ,气候变暖 ,以及沙尘暴频率加快 ,使年内时段干旱发生次数多 ,持续时间长 ,波及范围广 ,经济损失大 ,成为历史上罕见的特大干旱。造成草地、农耕地 0— 10 0cm以内土壤含水量均低于 4 .2 % (干土重 ) ,林地 0— 180cm内仅 3.6 % ,刺槐林地 0— 5 0 0cm平均仅 4 .2 % ,其直接后果是以林草地地力衰退为特征的人工林草地土壤干化日益严重 ,导致群落衰败以致大片死亡。但还有些植物经过灾变的考验 ,表现出高度抗旱耐高温特性 ,为我们以后防旱抗旱、退耕还林 (草 )

By taking Suide County of Shaaxi Province as a case study, this paper analyzes the frequently occurred drought for 5 years running from 1997 to 2001 due to the reduction of the total precipitation, poor effectiveness of precipitation, climate warming and frequent occurrence of sand-dust storms. The drought was characterized by a long duration, vast impact spatial extent and resulting in a serious economic loss, and was the extraordinarily serious in history. The drought made the average moisture contents of soils of the grasslands and farmlands (0～100 cm in depth), forestlands (0～180 cm in depth), and locust forestlands (0～500 cm in depth) be lower than 4.2, only 3.6 and 4.2% respectively. The direct consequences of the drought are to make the serious reduction of soil fertility of the grasslands and forestlands, increasingly serious dryness of soils under the artificially planted forests and grasses, and degeneration and death of the plant communities in a large area. Some plants, however, have a high resistance to drought, and they provide the scientific basis for selecting the plant species suitably growing in an arid environment so as to take the precautions against drought, withdraw from farming to planting forests and grasses, and distribute crops rationally.