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四川省亚洲黑熊(Ursus thibetanus)空间分布及人-熊关系研究
中文摘要

大型兽类空问分布的变化可以作为人类对生态系统影响的指标,尤其是对环境比较敏感的大型食肉类,如亚洲黑熊(Ursus thibetanus),其分布范围变化可以用来衡量人类对生态系统的影响程度。但是,我国已有的亚洲黑熊分布图由于尺度太大或者信息不准确,而很难将其应用到小尺度的研究和保护实践中去。为了在较好的尺度上精确绘制亚洲黑熊的空间分布,并研究影响其分布的景观因素,以及初步探讨亚洲黑熊和当地居民之间的相互作用, 2005~2007年作者在四川省实施了一项社会访问和实地调查相结合的系统调查。 四川省面积48.5万平方公里,依据地形地势以及气候的差异全省可被划分为东部盆地及盆周山地、西部高原及南部山区和平原三大部分。作者将全省划分为15㎞×15㎞的网格,利用网格内的森林覆盖率、平均海拔及公路密度分别对三个地区进行分层取样,共随机选取了494个网格(占全省21%)来做调查。到达网格后,调查人员对靠近森林边缘的村庄进行访问,并实地验证当地人报告的黑熊痕迹。如果村民说村庄附近无黑熊分布,调查者就到黑熊最好的栖息地中去做样线来验证当地是否有黑熊分布。利用Logistic回归模型结合环境变量来预测亚洲黑熊在未调查网格的分布概率,并确认影响其分布的环境变量。使用非参数统计方法对社会访问收集的信息进行分析,主要包括亚洲黑熊种群变化趋势,人-熊冲突,当地人对亚洲黑熊的态度以及针对亚洲黑熊的偷猎活动。 作者在360个网格中发现了业洲黑熊痕迹(占调查网格72.9%),而在其余的134个网格中没有发现黑熊痕迹。二元Logistic回归模型对已知有黑熊分布网格的预测正确率为89.0%,对已知无黑熊分布网格预测正确率为87.7%。模型预测四川38.6%的网格(n=2025)有亚洲黑熊分布。亚洲黑熊广泛分布在全省的森林生态系统中,主要集中于岷山、邛崃山、凉山等几大山系中。虽然森林覆盖在四川东部、南部及西部地区都是预测亚洲黑熊出现的积极因素,但其他相关因素在三个地区有所不同:在四川东部,亚洲黑熊分布还与平均海拔正相关;在南部,与灌丛盖度正相关,但是与农田覆盖负相关;在西部,农田覆盖是预测亚洲黑熊出现的积极因素。当地村民对亚洲黑熊分布有,无的信息的掌握十分准确:当地人报告有熊分布的网格中我们都找到了黑熊痕迹;只在一个网格中当地人报告说没有黑熊分布,但我们通过做样线找到了黑熊痕迹。 作者同时还收集到了1186份社会访问记录。在285个有熊网格中,被访者(n=855)认为亚洲黑熊种群在31.6%的网格内是增长的,在10.2%的网格内是稳定的,在58.2%的网格内是下降的。被访者认为新枪支管理政策(49.4%)和保护力度的加强(34.6%)是促使亚洲黑熊种群上升的主要原因,而偷猎(72.8%)和栖息地丧失(23.6%)是造成其种群下降最主要的原因。在35个网格中,当地人报告说亚洲黑熊种群已在过去的100年间消失,主要原因是大规模砍伐天然林造成亚洲黑熊栖息地的丧失(70.1%)以及偷猎(27.5%)。根据当地人的讲述,亚洲黑熊在236个网格(占有熊网格的66%)中与当地人之间存在冲突:当地人在174个网格中报告了黑熊取食庄稼的事例,在114刚格中报告了黑熊杀死家畜的事例,在49个网格中报告了黑熊伤人的事例。虽然大多数的被访者声明说他们遭受亚洲黑熊损害之后会报告给政府(30.3%,n=471个回答者)或者不采取任何行动(54.1%),还是有13.5%的村民承认他们会捕杀黑熊。当地人对亚洲黑熊的态度非常消极,只有6.5%的人说喜欢它们,大部分或是不在乎(43.2%)或是不喜欢(50.2%)它们。在有亚洲黑熊分布地区,被访者对于亚洲黑熊的态度与他们的年龄、受教育程度、职业、对亚洲黑熊了解多少以及是否遭受亚洲黑熊损害相关。年龄较大者以及对黑熊了解较少的人对于亚洲黑熊的态度相对更积极。遭受亚洲黑熊损害的人的态度比未遭受亚洲黑熊损害的人明显更消极(P<0.001)。虽然捕杀亚洲黑熊是违法行为,在117个网格中,仍旧有232个村民承认说当地仍旧存在偷猎亚洲黑熊行为。偷猎者捕杀亚洲黑熊主要为了获取熊胆和熊掌到市场上交易(78.5%)。偷猎黑熊方法主要包括枪打(42.0%)、陷阱或脚套(24.3%)以及放毒药(23.1%)。 利用系统取样及社会访问和实地调查相结合的方法,本研究收集到了亚洲黑熊分布有/无的可靠数据,并成功的建立了Logistic回归模型预测亚洲黑熊在四川全省的分布,同时还确认了网格内森林覆盖、农田覆盖、灌丛覆盖以及平均海拔是影响亚洲黑熊分布的重要景观因素。本研究中得到的在15×15平方公里网格的尺度上的亚洲黑熊分布图,不仅为将来的保护行动和研究提供了基础但重要的分布信息,也将为这个物种的长期监测提供本底数据。通过访问当地人,研究者收集到了与亚洲黑熊种群变化趋势、亚洲黑熊损害、偷猎及人的态度有关的信息,这些信息不仅反映了当地人和亚洲黑熊之间的相互关系,还将指导这个物种的保护方向和行动,因为所有成功的保护项目都离不开当地社区的支持。亚洲黑熊广泛分布的森林生态系统同时也是生物多样性热点区域,保护好了亚洲黑熊的栖息地和种群也将使同域分布的其他野生动物受益。我们利用物种分布有或无数据(Presence-absence data)来预测物种分布,以及通过社会访问系统收集人-野生动物相互作用信息,在国内是首次实践。通过亚洲黑熊调查所总结出的研究方法的框架应该电同样适用于其他大型食肉类的科学研究和长期监测。 关键词:亚洲黑熊 分布图 有/无数据 人-熊冲突 偷猎

英文摘要

Changes in the spatial distribution of large mammals may be a sensitive measure of human impacts on ecosystems, particularly true for large carnivores, such as Asiatic black bears. However, the previous distribution maps of Asiatic black bears were of too coarse a scale or too inaccurate, therefore of little use in research or conservation practice. Therefore we conducted a survey on Asiatic black bear combing social interviews and sign survey in Sichuan Province, Southwestern China, 2005~2007. The research aimed to creat a fine-scale map of the distribution of Asiatic black bears, identify landscape variables affecting the spatial range of this species and assess bear-human interactions using both presence-absence data and opinions of local villagers. Due to its wide range (485,000 ㎞²), Sichuan Province occupies very different landscapes. According to the physiographic feauters, we divieded the province into three regions for sampling: the estern basin and its surrounding mountains, the western plateau, and the southern mountains and plains. Then, we divided the province into 15×15 ㎞ cells, stratified them by forest cover, elevation and road density for each region and randomly selected 494 cells (21% of province) for surveys. In each cell, we interviewed villagers and ground-verified their reports of bear presence. We ground-truthed reports of bear absence by conducting transects for bear sign in the best available habitat. We used logistic regression models to identify key variables affecting presence of bears and predict their occurrence in unsampled cells. We used non-parameter statistics to analyze the information derived from interviewing local people, such as bear population trends, bear-human conflicts, villagers' attitudes towards bears, and poaching activities on bears. We detected bears in 360 cells (72.9% of surveyed cells). Models correctly predicted bear occurrence in 89.0% of cells where we detected bears and 87.7% of samples cells where bears were absent. Models predicted 38.6% of Sichuan to be occupied by bears. Bears were distributed in forest ecosystem widely of Sichuan Province, with the core range located within the Minshan, Qionglai, and Liangshan Mountains. Forest cover was positive predicator in all three regions, but the other predictors for bear occurrence were different. In the eastern region, cells in higher elevation were more apt to be occupied by bears, lin the southern region, shrub cover was a positive predicator of the presence of bears, whereas agricultural cover had the strongest negative effect on bear occurrence. In the western region, agriculture was positively related to the presence of bears. Local villagers were accurate in their knowledge of bear presence or absence: in all cells where they reported bear presence, we found bear signs in forest; only in one cell where they reported bear absence, we found bear sign by conducting transects. We collected other information by interviewing 1186 local villagers. Interviewed villagers (n=855) thought that bears were increasing in 31.6%, stable in 10.2%, and decreasing in 58.2% of cells with bears (n=285 cells). Where bear populations were perceived to be increasing, villagers thought enforcement of new gun policy (49.4%) and conservation strategies (34.6%) were main causes; where bear populations were perceived to be decling, villagers identified poaching (72.8%) and habitat loss (23.6%) as the major causes. Bears were reported to be extirpated in 35 cells in past 100 years mainly because of extensive logging of natural forest and poaching. Bears caused conflict with local people in 236 cells (66% of bear present cells) by raiding crops (n=174 cells), killing livestock (n=114 cells) and/or attack on human (n=49 cells). Among villagers who claimed their response toward bear damage, 54.1% of them would tolerate the loss and 30.3% of them would report the damage caused by bears to government, still, 13.5% of villagers claimed that they would take retaliation towards problem bears. Local people held very negative attitudes towards bears: only 6.5% among them claimed that they liked bears; all other people either disliked bears (50.2%) or did not care about them (43.2%). In bear present areas, respondents' attitudes towards bears were related to their age, education, job, knowledge level on bears, and whether suffered bear damage. Those who suffered loss from bear damage held significant more negative attitudes towards bears than those who did not (P<0.001). Even though killing bears were illegal, 232 villagers in 117 cells admitted that there were poaching activities on bears around their villages. Poachers killed bears mainly for trade of their valuable parts (gall bladder and paws, 78.5%). Poaching methods included shooting by gun (42.0%), traps or snares (24.3%) and poisoning (23.1%). Using presence-absence data, we succeeded to build a model to predict the spatial range of black bear in Sichuan and indentify forest, agriculture, and shrub cover, and mean elevation within cells as the key landscape variables affecting bear presence. Such fine-scale and accurate map will not only provide basic but important information of bear distribution for researchers and managers, but also is the baseline for long-term population monitoring. By interviewing local villagers, we derived useful information on bear population trends, bear-human conflicts, poaching on bears, and villagers' attitudes toward bears. Such information reflected bear-human interactions and will be useful for future conservation planning and actions, as any successful conservation programs need the support from local community. It is the first practice in China using presence-absence data to map large mammal distribution range and using interview data to systematic investigate human-wildlife interactions. The schemes we created in this study will also be useful for other large carnivores in China, such as snow leopard and brown bear. Keywords: Asiatic black bear, Distribution map, Presence-absence data, Bear-human conflicts, Poaching

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