放牧对冶勒自然保护区大熊猫生境的影响

Effect of Grazing on Giant Pandas'habitat in Yele Nature Reserve

四川冶勒自然保护区周边村民的牲畜基本上都在保护区内放养。为研究放牧和大熊猫对竹类的利用及放牧强度与竹类的关系 ,利用Forageratio选择指数 ,Pearson相关分析和联列表独立性检验 ,对调查数据进行分析。结果表明 ,大熊猫活动区海拔为 2 870～ 390 0m ,并喜欢选择竹类盖度为 5 0 %～ 10 0 % ,竹类高度 2～ 3m ,竹类生长状况好的竹林。而放牧海拔为 2 70 0～ 4 0 0 0m ,放牧对竹类的盖度、高度、生长状况没有选择性 ,为随机利用。放牧海拔与大熊猫活动海拔无显著相关。大熊猫在放牧生境活动的频率较低 ;放牧生境中竹类的成竹平均密度和竹子平均密度都低于大熊猫活动生境 ,枯死竹比例高于大熊猫活动生境。放牧强度与竹类的有、无和竹类盖度是相关联的 ,大熊猫出现与否也与放牧活动相关联 (在 95 %的置信度 ,P <0 0 5 )。放牧强度强的生境没有大熊猫活动 ,竹子的盖度也较低。由于放牧活动对竹类的生长和盖度造成影响 ,从而影响大熊猫对放牧生境的利用 ,在保护区内应采取一定的措施控制放牧活动。

Impact of grazing on giant pandas'habitat was studied at Yele Nature Reserve, Sichuan in 2001. Forage ratio selection index is used to assess the bamboo utilization of both giant pandas and grazing. Among 482 sampling spots of our survey, panda traces at 54 sampling spots, grazing at 159 sampling spots were recorded. We use bamboo coverage, height, growth status, density and elevation to characterize habitats of both the giant panda and livestock and sort grazing intensity into intensive, medium, and weak. The results of analyses of Forage ratios, contingency tables and Pearson correlation suggest that a) the giant panda preferred to habitats of 2 - 3 m height bamboo, bamboo coverage of 50% - 100%, better bamboo growth status at elevation of 2 870 - 3 900 m; b) livestock, occurring at elevation of 2 700 - 4 000 m, showed no preference the above factors; c) at intensive grazing sampling spots no panda traces was found and bamboo coverage was less than 50% at 80% of sampling spots; d) bamboo density and adult bamboo density were less at the sampling spots where grazing occurred than the sampling spots where giant pandas occurred, but proportion of dead bamboo individuals was higher than the sampling spots of giant panda, e) and with the presence of bamboo or not and bamboo coverage is dependent on grazing intensity; f) giant panda avoid the grazing habitat. It is concluded that grazing has definite impact on pandas' habitats and therefore it should take measures to control grazing activities in the nature reserve.