和田地区绿洲外围农田防护林带的防护效益

在和田地区新垦农地外围的流动沙地种植新疆杨乔木+沙拐枣灌木复合防护林,通过布设风速风向观测仪、沙尘通量梯度仪、温湿度和辐射等测定仪于林带前后,研究防护林网的防护效益,为营建绿洲外围防护林和合理开发利用荒漠区的土地资源提供理论依据。结果表明,防护林带的防风效能随着高度的增加而减弱,大于起沙风速(6m/s)时,新疆杨林带、沙拐枣林带在0.5m处的防风效能分别为67.2%和94.5%,在3m处的防风效能分别为31.3%和33.7%。随着风速的增大,沙拐枣林带和新疆杨林带的防风效能均减弱,新疆杨林带的减弱更为明显。防护林带有效地降低了地表风速,减轻地表风蚀。林带内的输沙量仅为外围的10%左右。此外,林带内的太阳辐射强度下降,温度降低,湿度显著增加。由此可见,防护林可以有效地起到防风固沙,改善区域小气候的作用。

Protection Benefits of Farmland Shelterbelt in Oasis Periphery of Hotan Region

Populus allba and Calligonum mongolicunl farmland shelterbelt was planted in a moving sandy land outside newly reclaimed farmland in Hotan region. HOBO anemoscope, hygrograph, thermograph and sand sampler were set in the front and back of the shelterbelt, and the apparatus were conducted to determine the protection benefits of the farmland shelterbelt. The study was expected to provide a theoretical basis for building the outside protection forest and rationally exploiting and utilizing land resources in the deserted area. Results showed that wind-break potency of the shelterbelt decreased with the height. When wind velocity was greater than 6 m/s, wind-break potencies for the Populus alba belt and Calligonum mongolicunl belt at the height of 0.5 m were 67.2% and 94.5% and at the height of 3 m, 31% and 33%, respectively. Wind-break potency decreased with wind velocity and the Populus alba belt's effect was more obvious. Farmland shelterbelt played an important role in decreasing wind velocity and reducing wind erosion, and sand transportation in the shelterbelt was about 10% as compared with mobile sandy land. Besides, radiation and temperature were decreased, and humidity was increased sharply under the shelterbelt. Farmland shelterbelt plays an effective role in decreasing wind velocity, fixing mobile sandy land and optimizing the microclimate.