丹顶鹤多尺度生境选择机制——以黄河三角洲自然保护区为例

生境在鸟类生活史中发挥着重要的作用,关系到鸟类的生存和繁衍。由于鸟类对环境变化的响应发生在等级序列空间尺度上,基于多尺度的研究更能深入刻画鸟类-环境之间关系。以丹顶鹤(Grus japonensis)为研究对象,以其迁徙和越冬的重要地区-黄河三角洲自然保护区为研究区域,应用等级方差分解法和等级划分法,分析丹顶鹤与微生境、斑块、景观尺度因子之间的关系,探求丹顶鹤生境选择的主要影响因素和尺度。等级方差分解结果表明,在第1等级水平,景观尺度因子与微生境、斑块尺度因子之间的联合效应大于独立效应,景观尺度因子的独立效应大于微生境和斑块尺度因子;在第2等级水平,景观尺度上的景观组成因子重要性大于景观结构因子,微生境尺度上的植被和水分因子为重要影响因素。等级划分结果表明,景观尺度上,翅碱蓬滩涂、水体面积大小是主要影响因素;微生境尺度上,植被盖度和水深为主要限制因子;在斑块尺度上,斑块类型对丹顶鹤生境选择最为重要。研究认为,在黄河三角洲自然保护区,景观尺度是影响丹顶鹤生境选择的主要尺度,景观尺度因子通过与微生境和斑块尺度因子的独立和联合作用制约着丹顶鹤在保护区的生境选择和空间分布格局。建议加强对翅碱蓬滩涂、芦苇沼泽、水体等湿地生境的保护和管理,规范和控制保护区内人类活动强度。

A multi-scale analysis of red-crowned crane's habitat selection at the Yellow River Delta Nature Reserve, Shandong, China

Habitat plays an important role in the life history of birds. Habitat quality is directly related to the bird's survival and reproduction. Since bird species respond to the habitat variation simultaneously across a range of organizational levels, multi-scale approaches can potentially better describe bird species-environment relationships compared to single-scale approaches. Red-crowned crane (Grus japonensis) is a rare, endangered species living in native wetlands. The Yellow River Delta Nature Reserve (YRDNR) in Shandong province is one of most important sites for this species' migration and wintering. Here, we take YRDNR as a case study to explore the main limiting factors and scales of habitat selection of the crane at microhabitat, patch and landscape scales. We collected the red-crowned crane distributional data and microhabitat level factors from two field surveys, and extracted the patch or landscape level factors using remote sensed images. We used hierarchical variance partitioning methods to partition explainable variance by habitat factors in the red-crowned crane distributional data at two hierarchical levels. The first level of analysis partitioned variance explained by microhabitat, patch and landscape level factors alone and in combination. The second level partitioned variance explained by vegetation and water factors independently and jointly at microhabitat scale, landscape composition and configuration factors independently and jointly at landscape scale. By comparing the amount of variance occupied by habitat factors at each hierarchical level, we examined their independent and joint effects on habitat selection of red-crowned crane. Moreover, we used hierarchical partitioning methods to segregate the independent effects of each habitat factors separately, and explored their contributions to the habitat selection. The results showed at the first level, a majority of variance explained by the jointly effect of landscape level factors with microhabitat (10.8%) or patch (25.3%), or microhabitat and patch (28.9%) level factors. Meanwhile, landscape level factors independently accounted for a larger amount of the explained variance (12.7%) than microhabitat (6.0%) or patch (1.6%) level factors. At the second level, the landscape composition was more important than the landscape configuration at landscape level, and the vegetation and water contributed more explainable variation at the microhabitat scale. The results of hierarchical partitioning methods showed that seabilite tidal flat, and water area are the main habitat factors at landscape scale since their Z value of independent effects are statistically significant. Vegetation coverage and water depth contributed more explanatory power at microhabitat scale. At patch scale, patch type was the predominant factor. Besides, the road density also had independent effects on habitat selection of red-crowned crane. This study suggested the landscape scale is the main scale related to the distribution of red-crowned crane. Landscape level factors, together with microhabitat and patch level factors, jointly controlled habitat selection in YRDNR. To protect the wetland habitat for red-crowned crane, we proposed to take effective measures to strengthen the protection and management of the tidal flat, weed marsh or water body, and regulate or control human activities that threaten and destroy the wetland habitat in YRDNR.