普洱市亚洲象栖息地适宜度评价

Habitat suitability assessment for Asian elephant in Pu'er prefecture in the Yunnan province of China

亚洲象(Elephas maximus)属于我国Ⅰ级保护动物,在中国仅分布于云南省西双版纳国家级自然保护区、普洱市的思茅区、澜沧县和江城县,以及临沧南滚河国家级自然保护区。将普洱全境作为研究区域,利用野外调查数据,结合遥感与地理信息系统技术,运用生态位因子分析(ENFA)模型对普洱市亚洲象的栖息地适宜度进行了评价,并预测了适宜栖息地的分布。发现:普洱市亚洲象栖息地的边际值为0.991,表明亚洲象在普洱市境内对环境变量的选择不是随机的;耐受值为0.315,表明亚洲象在普洱市境内生态位较窄,受环境条件的制约。根据模型计算得到的栖息地适宜度指数,将普洱市的亚洲象栖息地分为最适栖息地,较适栖息地,边际栖息地和非栖息地4个等级,面积分别为409.32、574.32、2909.48、38722.32 km2。最适栖息地仅占全市面积的0.96%,而非栖息地占90.86%。利用GIS和Biomapper 4.0生成亚洲象栖息地分布图,发现普洱境内最适栖息地和较适栖息地面积狭小。对最适栖息地、较适栖息地和边际栖息地进行景观格局分析的结果表明,3种类型的栖息地破碎化均十分严重,连通度较低,栖息地内受到较大程度的人类活动的干扰。因此建议在普洱和西双版纳间尽快建立野生动物生态廊道,以加强亚洲象各种群间的交流。

The Asian elephant （Elephas maximus ） is listed as a first-class protected species in China, and is only distributed in Xishuangbauna, Pu＇er, and Lincang prefectures of Yunnan Province. The main threats to the survival of elephants in China were habitat loss and fragmentation. Only 5 elephants were reported in Pu＇er in 1996, and currently, there are over 80 elephants belonging to 8 groups living in the region. In this study, we collated 152 elephant occurrence points within the entire Pu＇er range in 2010, and assessed habitat suitability for Asian elephant in Pu＇er, based on Ecological Niche Factor Analysis （ENFA） of the field survey data. We also predicted the distribution of suitable habitats for elephants in Pu＇er. The marginality value obtained from ENFA was 0.992. This resuh indicated that the deviation of the preferable niche of elephants was different from the average value of the environment, and that elephants chose their habitat non-randomly. The tolerance value was 0.315, which indicated that the niche of Asian elephant was narrow, and that environment indicators restricted the survival of elephants. Results showed that the elephants in Pu＇er preferred natural forest with low elevation （ 〈1419 m） and moderate slopes （ 〈14~ ）, as well as areas far from streams and human disturbance （villages and roads）. We divided elephant habitat in Pu＇er into 4 categories： optimal habitat （409.32 km2）, suitable habitat （574.32 kmz） , marginal habitat （2909.48 km2） , and unsuitable habitat （38722.32 kmZ）. The unsuitable habitat aecounted for 90.86% of the total area, whereas the optimal habitat occupied only 0.96%. Natural forest is the major vegetation type in optimal （ 55.6%）, suitable （ 54.55% ）, and marginal （48.21%） habitats, but it constituted only 33.05% of the unsuitable habitat, indicating that natural forest is the preferred habitat for Asian elephants. Aeeording to landscape structure analysis using FRAGSTATS, the mean patch fraetal dimension indices （FRAC_MN） for marginal, suitable, and optimal habitats were found to be close to 1, and the meaneontiguity indices （CONTIG_MN） were found to be 0.12-0.15. Landscape analysis showed that the optimal, suitable, and marginal habitats all suffered severe fragmentation, low connectivity, and high levels of human disturbance. In comparison with real distribution, the predicted map incorporated some farmlands where Asian elephants forage. The proportion of optimal and suitable habitat in Pu＇er is very low, owing to the loss of natural forest and the cultivation of economic plants. It is critical to establish protected areas in the habitat of Asian elephants, in combination with effective conservation measures. In addition, the three main areas of elephant distribution in Pu＇er are isolated. It is understood that low connectivity among populations impedes important communication among different population groups. Therefore, it is also necessary to establish and restore ecological corridors to link the current elephant habitats in Pu＇ er, and to increase their connection with other elephant populations in Xishuangbanna.