阿尔金山自然保护区基于野牦牛、藏野驴、藏羚羊适宜栖息地的生态容量估测

摘要

阿尔金山国家级自然保护区保护了以野牦牛( Bos mutus)、藏野驴( Equus kiang)、藏羚羊( Pantholops hodgsoni)为代表的青藏高原特有野生动物及其栖息地,但是近年来野生动物数量的快速增长引发了栖息地退化的问题,科学量化阿尔金山自然保护区各类栖息地对野牦牛、藏羚羊、藏野驴的生态容量,并提出相应的野生动物管理措施,是实现保护区可持续管理的根本途径。本文应用遥感技术和地面调查相结合的方法,系统分析了保护区内野牦牛、藏野驴和藏羚羊的栖息地需求,建立了植物生物量和NDVI 的关系模型,结合三类野生动物的食性分析,估测了适宜栖息地(高寒草原、高寒荒漠草原、高寒草甸、高寒荒漠)为三类野生动物提供的可食植物量,推算了适宜栖息地和整个保护区可以承载三类野生动物的生态容量。结果表明：阿尔金山自然保护区内野牦牛、藏野驴和藏羚羊的适宜栖息地面积分别为31866.07、24035.51、24035.51 km2,三类野生动物的适宜栖息地之间相互重叠,藏野驴和藏羚羊的适宜栖息地基本相同；全保护区内,高寒草原、高寒荒漠草原、高寒荒漠和高寒草甸分别提供了3944.91×104、3126.32×104、138.19×104、564.49×104 kg可食植物量；结合三类野生动物的栖息地重叠程度及食物需求量分析,得出阿尔金山保护区的最大生态容量为野牦牛7951头/a、藏野驴6907头/a、藏羚羊27094只/a；结合三类野生动物对食物资源的占有率估计,得出阿尔金山三类野生动物的生态容量变幅为野牦牛3976—7156头/a,藏野驴3454—6216头/a、藏羚羊13547—24385只/a。根据阿尔金山自然保护区各类栖息地对三类野生动物的生态容量,提出适当控制藏野驴种群数量、增加藏羚羊种群数量的建议,以促进野生动物种群数量的持续增长和栖息地的有效保护。%Altun Mountain National Nature Reserve ( AMNNR) on the Qinghai-Tibetan Plateau, China, is a major refuge for three wild ungulates;wild yak ( Bos mutus) , kiang ( Equus kiang) , and Tibetan antelope ( Pantholops hodgsoni) . This nature reserve is important for conserving these three wild endemic ungulates and their habitats. Over decades of conservation, the populations of these three ungulates have increased rapidly. However, the administrators of AMNNR considered that the kiang might have become overpopulated, which would result in habitat degradation. Thus, it is vital implement wildlife management planning based on the quantification of ecological carrying capacity for sustainable nature reserve management. In this study, vehicular transects were conducted to survey the distribution data and record the populations of wild yak, kiang, and Tibetan antelope from May to June, 2012, and June to July, 2013, in the AMNNR. We integrated remote sensing data analysis with on-the-ground plot surveys to identify suitable habitats ( alpine steppe, alpine desert steppe, alpine desert, and alpine meadow) for all three ungulates, and we estimated habitat production. A dietary analysis of wild yak, kiang, and Tibetan antelope was completed to estimate the amount of edible grasses required for the three wild ungulates in suitable habitats. Using the empirical formula ( calculation of the proper carrying capacity of rangelands) provided by the PRC Ministry of Agriculture, we quantified the carrying capacity for all three species in suitable habitats and in the whole natural reserve. The results showed that areas of suitable habitat for wild yak, kiang, and Tibetan antelope were 31866. 07 km2 , 24035. 51 km2 , and 24035. 51 km2 , respectively. There were big overlaps in the suitable habitats for all three wild ungulates, which shared almost the same suitable habitats. Within the suitable habitats, alpine steppe, alpine desert steppe, alpine desert, and alpine meadow could potentially provide 3944.91×104 kg, 3126.32× 104 kg, 138.19×104 kg, and 564.49×104 kg edible grasses, respectively for these three species. Considering the overlaps of suitable habitats and the different requirements of the three species, the maximum ecological carrying capacities of the whole nature reserve were estimated to be 7951 heads/year for wild yak, 6907 heads/year for kiang, and 24959 heads/year for Tibetan antelope. The ecological carrying capacity ranges under different probabilities of food availability were 3976—7156 heads/year for wild yak, 3454—6216 heads/year for kiang, and 13547—24385 heads/year for Tibetan antelope. Comparison of the actual population size and that which could be supported by the ecological carrying capacity of suitable habitats within the AMNNR, indicated that kiang are overpopulated, wild yak are close to the maximum ecological carrying capacity, and Tibetan antelope are underpopulated. Therefore, the best management practice should be applied to control the kiang population and to promote the Tibetan antelope population. Such action would balance the different wildlife species that share the same habitats and would maintain habitat health to sustain the AMNNR. Conservation efforts should focus on the long-term ecological monitoring of habitats in the reserve to avoid grassland degradation caused by the overpopulation of animals.