白鹤中途停歇地主要食物藨草球茎密度的空间插值方法研究

扁杆藨草(Scirpus planiculmis)和三江藨草(S.nipponicus)的球茎是迁徙白鹤(Grus leucogeranus)在莫莫格中途停歇地的主要食物。2010年9月15～25日,对莫莫格白鹤集中停歇地鹅头泡湿地的20条样线上100 m等间隔470个取样点进行了地下0～20 cm的藨草球茎的取样工作。基于此,采用反距离权重、4种径向基函数和普通克里格共6种空间插值方法模拟了该区域藨草球茎密度。交叉验证和插值结果的空间分布图对比,径向基函数中的张力样条插值效果最佳,是最适于该区域挺水植物藨草球茎密度的空间插值方法。张力样条插值结果表明:研究区内藨草球茎密度均值为(46.0±44.3)个/m2。其中,<25个/m2的面积占研究区的41.7%,25～100个/m2的面积占45.9%,而>100个/m2的面积仅占12.4%。研究结果为下一步分析白鹤迁徙种群与环境因子的生态关系、预测该地区白鹤的环境容纳量提供十分重要的基础数据。

Comparison of the spatial interpolation methods for the tuber density of two Scirpus species: main food of Siberian cranes at the stopover site

The tubers of Scirpus planiculmis and S.nipponicus are the main food for migratory Siberian Cranes Grus leucogeranus at the Momoge National Natural Reserve (MNNR) of Jilin Province, Northeastern China. During 15-25 September 2010, we sampled tubers of these two species at 470 points evenly distributed at 100 m intervals along 20 transect lines at Etoupao wetland, the area of the highest concentration of migratory Siberian cranes at MNNR. Six different methods of spatial interpolation including inverse distance weighting (IDW), four radial basis functions (RBF) and ordinary kriging (OK) were employed to simulate the Scirpus tuber density in the study area based on the field sampling data. According to the results of the cross-validation and spatial distribution, the spline with tension of RBF is the most optimized method with the highest accuracy. The results of this method showed that the mean tuber density was 46.0±44.3 no./m². Areas with tuber densities < 25, 25-100, and > 100 /m² occupied 41.7%, 45.9% and 12.4% of the study area, respectively. The results provide basic, yet critical, data for determining the relationship between Siberian cranes and tuber availability, and predicting the environmental capacity of Etoupao wetland for supporting migratory Siberian cranes.