载畜率对短花针茅荒漠草原植被覆盖的影响

The Influence of Stocking Rates on Vegetation Coverage in Stipa breviflora Desert Steppe

载畜率对草地生态系统的稳定有着重要的作用,研究其对植被的影响可为草畜平衡管理提供科学依据。基于四期Landsat卫星数据,利用像元二分模型,对不同载畜率水平的短花针茅荒漠草原植被覆盖进行了近13年的动态监测。研究结果表明,植被覆盖呈现对照区>轻度放牧区>中度放牧区>重度放牧区。多年围封后,对照区植被覆盖由以中低覆盖为主转变为以高覆盖为主,高覆盖植被显著高于试验前;轻度放牧区植被由以中低覆盖为主转变为中覆盖植被为主,中覆盖植被显著高于与试验前。中度和重度放牧区植被多年仍以中低覆盖植被为主,但次要植被覆盖却由低覆盖转变为中覆盖,植被总覆盖度高于试验前,呈增长趋势。试验结论认为围封和轻放牧措施明显增加植被覆盖度,有助于短花针茅荒漠草原可持续发展,而中度和重度放牧显著减少植被覆盖度,但是由于冬春季休牧管理及降水量的共同作用促使中度和重牧处理区植被总盖度高于试验前。

Stocking rate plays an important role for stability of grassland ecosystem. Studying the influence of stocking rate on grassland can provide a scientific basis for balance of livestock and grassland. In the paper, using pixel two-division model, vegetation coverage of different stocking rates in Stipa brevi- flora desert steppe was estimated in nearly 13 years based on the four period data of Landsat satellite. The research results were as follows, vegetation coverage in control area was the highest,vegetation coverage in lightly grazed area was the second, vegetation coverage in moderately grazed area was the third and vegetation coverage in heavily grazed area was the lowest. In control area, the main vegetation coverage transferred from medium-low coverage to high coverage, which increased significantly after many years of enclosure. High vegetation coverage was significantly higher （P〈0.05） in control area than before the test. In light grazed area, the main vegetation coverage transferred from medium-low coverage to medium coverage, and the medium coverage vegetation was significantly higher than before the test. The main vegetation coverage in moderately grazed area and heavily grazed area was not changed, but the second main coverage was changed from low coverage to medium coverage; Their vegetation coverage was higher than before the test. The conclusion was that. lightly grazing and no grazing can significantly increase vegetation coverage, and make the Stipa breviflora desert steppe to sustainably develop. Although there were higher stocking rate in moderately and heavily grazed area, but their vegetation coverage was higher than that before the test, the reason was that no grazing management in winter and spring, and abundant rainfall promote the vegetation coverage.