西双版纳野象谷景区亚洲象取食对五种植物的影响

The impact of Asian elephant browsing on five plant species at Wild Elephant Valley,Xishuangbannan,Yunnan of China

本研究在西双版纳利用样线调查法调查亚洲象的取食对野象谷景区常见分布的5种植物即酸苔菜、象鼻藤、粗糠柴、翅果麻和黄牛木的影响,调查中记录样线上每一目标植株的基径、高度、影响类型、影响程度等信息。结果表明:(1)植物受影响的数量与其植株总数之间的相关性不大(Pearson correlation,r=0.608,P=0.277);(2)亚洲象对5种植物的偏爱程度不一样,酸苔菜、象鼻藤、粗糠柴和翅果麻都是大象喜爱的食物,尤其是象鼻藤(偏爱指数=1.4855),而黄牛木不受大象喜爱(偏爱指数=0.5855);(3)亚洲象对5种植物有不同的影响方式和影响程度,酸苔菜以主干折断和枝叶损失为主,受大象的取食影响最严重,象鼻藤虽然是大象最喜爱的食物,但受到的取食影响最小,粗糠柴以枝叶损失和主干折断为主,翅果麻以枝叶损失为主,同时也是唯一被亚洲象剥皮的植物,黄牛木以枝叶损失为主,被推倒的情况最普遍。树干基部直径为3-8 cm的植株最受大象偏爱。亚洲象对植物的选择性以及植株自身的特性是导致上述差异的主要原因。建议后续开展长期的调查以了解亚洲象对这些植物种群数量及群落结构的影响,同时应采取有效保护措施以避免象群在当地过于集中的现象。

Transect surveys were used to study the browsing impact of Asian elephants＇ on Ardisia solanacea,Dalbergia mimocoides,Mallotus philippinensis,Kydia calycina and Cratoxylum cochinchinese at Wild Elephant Valley in Xishuangbanna,Yunnan,China. In total,3 197 trees were studied and tree damage in relation to species,basal stem size,impact type,and impact level were recorded and analyzed. Our results showed there was no correlation between the intensity of foraging on a plant and its abundance（ Pearson correlation,r = 0.608,P = 0. 277）. While foraging,Asian elephants showed preferences for Ardisia solanacea,Dalbergia mimosoides,Mallotus philippinensis and Kydia calycina,with the highest preference being for Dalbergia mimosoides（ Preference ratio = 1.4855）. Avoidance of certain species was also shown,with Cratoxylum cochinchinese showing the highest avoidance by elephants（ Preference ratio = 0.5855）. Ardisia solanacea suffered the most intense impact from foraging in the form of trunk breaking（ 52. 21%） and leaf foraging（ 45. 38%）.Mallotus philippinensis experienced heavy leaf foraging（ 53. 04%） and trunk breaking（ 41. 44%）,while Kydia calycina was mainly utilized by leaf foraging（ 53. 55%） and was the only plant in our study barked（ 18. 03%） by elephants. Cra-toxylum cochinchinese was mainly utilized by leaf foraging（ 56. 35%） and was most frequently pushed over（ 16. 02%） by elephants. Interestingly,although it was the most frequently utilized species by foraging elephants,Dalbergia mimosoides experienced the lowest level of impact. Stem size was also a factor in the foraging preference of Asian elephants as trees with a stem size between 3- 8 cm were most frequently utilized. More work is needed to better understand how the Asian elephant＇s selective browsing could impact plant species and overall community structure within its habitat. We suggest conservation measures should be taken to avoid high concentrations of Asian elephants in a specific area for a lengthy period of time.