祁连县天然草地地上生物量及草畜平衡研究

论文利用2013—2014年的MOD13Q1数据、草地地上生物量鲜重实测数据、多年降水数据和统计年鉴数据,建立了祁连县草地地上生物量与牧草鲜重的遥感监测模型以及不同季节放牧草场的理论载畜量模型,分析了天然草地草产量年内动态变化与载畜量平衡状况并对草畜调控进行模拟。结果表明:MODIS增强型植被指数EVI的指数函数可以较好地模拟祁连县草地地上生物量鲜重,精度达到71%;年内牧草生长呈单峰曲线,7月草地可食产量达到峰值2 322.61 kg/hm~2,12月最低,为702.06 kg/hm~2;祁连县冷暖季平均可食鲜草产量分别为1 728.14和1 604.70 kg/hm~2,年可食鲜草总量分别达到7.74×10~8和7.82×10~8kg;暖季、冷季和全年的理论载畜量分别为1.517 8、0.637 0和0.931 4羊单位/hm~2,暖季、冷季和全年的超载率分别为101.70%、261.19%和149.22%;保持现有的家畜数量,需在暖季草场和冷季草场分别补饲牧草0.36×10~8和7.17×10~8kg;保持现有草场,则暖季草场和冷季草场分别需要减6.68×10~4和53.64×10~4羊单位;暖季不进行补饲,冷季草场家畜在减少40%的情况下,依旧需要补饲1.17×10~8kg。

Study on the Aboveground Biomass of Natural Grassland and Balance between Forage and Livestock in Qilian County

By use of statistical yearbook data, years precipitation data, grassland investigation data and MOD13Q1 during 2013-2014 in Qilian County, the models of monitoring grassland aboveground biomass (GAB) and theoretic livestock carrying capacity in different grazing seasons were established. Changes of available grassland yield and livestock carrying capacity were analyzed. Results suggested that the exponential function of MODIS-EVI (Enhanced Vegetation Index) can best simulate the green yield of GAB in Qilian. The average precision of the monitoring model was 71.0%. The monthly dynamic growth of forage during the year was featured by a unimodal curve. The edible grass yield reached a peak of 2 322.61 kg/hm² in July, and got to the lowest of 702.06 kg/hm² in December. Average green yields in cold and warm seasons were 1 728.14 and 1 604.7 kg/hm², respectively. The total available green forage yield in Qilian County were 15.56×10⁸ kg, in which warm seasonal grazing rangeland was 7.74×10⁸ kg, cool seasonal grazing rangeland was 7.82×10⁸ kg. The theoretical carrying capacity of grassland in cold season, warm season and the whole year were 1.517 8, 0.637 0 and 0.931 4 sheep unit/hm², respectively. The overgrazing rate was 101.7% in warm season, 261.19% in cold season and 149.22% in the whole year. If the overgrazing livestock cannot be fully decreased, about 0.36×10⁸ and 7.17×10⁸ kg of forage should be supplemented in cold and warm season, respectively. If keep the existing grassland, 6.68×10⁴ and 53.64×10⁴ sheep units should be reduced in cold and warm season, respectively. Even if the overgrazing livestock is decreased by 40% in cold season, about 1.17×10⁸ kg of forage should be supplemented.