内蒙古达赉湖地区赤狐生境选择及生境景观特征分析

近年来,干旱、鼠害及人为对草原的过度开发利用等对达赉湖地区赤狐的数量及分布范围造成了很大影响。借助于主成分分析、Bailey’s判别分析、遥感和地理信息系统对达赉湖自然保护区赤狐的生境选择及生境的景观特征进行了研究。在赤狐家域内采用样线法和样方法,共设置10 m×10 m样方245个(实验样方101个,对照样方144个),并测定样方内的7个生境因子:植被类型、隐蔽级、食物丰富度、雪深、距水源距离、距围栏距离、距居民点距离。对样方内数据进行主成分分析得出,食物和隐蔽性是赤狐生境选择的主要因子,距居民点距离和距围栏距离是赤狐生境选择的次要因子,雪深和距水源距离是赤狐在生境选择中未表现出选择和利用的因子。利用Bailey’s方法和基于赤狐的生境分布图的景观统计得出:赤狐偏好选择柳灌丛和芦苇塘两种生境,这两种生境的总面积约为1093.47 km2,占研究区总面积的14.05%;赤狐随机利用河道、典型草原和草甸草原3种生境类型,这3种生境的总面积约为4721.79 km2,占研究区总面积的60.67%。;回避的生境为冰面和沙化草地,总面积约为1968.09 km2,占研究区总面积的25.29%。基于地理信息系统和Fragstats的景观特征分析得出,赤狐最适宜生境的面积最少,斑块数量最多,平均斑块面积最小,平均形状指数最小,平均斑块距离最大;其次是较适宜生境和不适宜生境;一般适宜生境的面积最多,斑块数量最少,平均斑块面积和平均形状指数最大,平均斑块距离最小。赤狐多分布于斑块较大的适宜其生存的生境或分布于由这些斑块形成的生境斑块镶嵌体中。

Red fox habitat selection and landscape feature analysis in the Dalai Lake Natural Reserve in Inner Mongolia

Red fox, a canine predator inhabiting in the grassland of eastern Inner Mongolia, is positioned near the top of the food chain. It plays an important role in rodent control. Consequently, research on red fox helps scientists accumulate basic data and offers a scientific basis for the protection of grassland ecosystems and red fox management. Red fox habitat selection in the Dalai Lake Natural Reserve was systemically studied from November 2009 to January 2010 and from March to April 2010. Line transects were used for 101 plots known to be used by the red fox and for 144 comparison plots. We processed our field data and analyzed them using principal component analysis. Using landform analysis of the study area and other relevant research work, we defined seven significant factors influencing habitat: vegetation type, sheltering class, food abundance, snow depth, distance to water sources, distance to fences, and distance to residential areas. Our results show food and sheltering class were two key factors that affected red fox habitat selection. Distance to residential areas and distance to fences also affected the red fox habitat selection to some degree. Snow depth and distance to water sources had minimal effects on red fox habitat selection. Using Bayesian methods and 3S technology, we analyzed landscape features and studied red fox habitat distribution using an existing fox distribution map. We found that the red fox prefers two kinds of habitats: reed pond and willow shrub. Reed pond and willow shrub covered 1093.47 km² of the analysis area; red foxes also occasionally use watercourses, typical grassland, and meadow steppe which covered 4721.79 km²; unsuitable habitat, including open water covered 1968.09 km². Those were 14.05%, 60.67%, and 25.29% of the analysis area, respectively. The unsuitable patches were mainly water covered with little sand; they were not studied. We concluded most of the suitable habitat patches for red fox are relatively smaller in size and fewer in number compared with red fox habitat in other areas previously studied by other researchers. The shapes of the three types of habitat listed above are suitable for the survival of the red fox, but the distribution of each type of patch is too concentrated to provide adequate distribution of the red fox population. We conclude the number of suitable patches should be increased to provide additional and more diverse types of grassland patches suitable for red fox across the landscape. We recommend controlling grazing to increase the density and the height of grass which, in turn, improves available sheltering habitat in patches suitable for red fox. Meadow used for grazing and meadow reserved for red fox habitat must be strictly separated. Through this method some relatively suitable patches could be improved to highly suitable patches for red fox. This would increase the red fox population and provide improved rodent control.