NORTHERN AND MID-LATITUDE SOIL DATABASE, VERSION 1

The U.S. Department of Agriculture, Agriculture and Agri-Food Canada, the Russian Academy of Agricultural Sciences, the University of Copenhagen Institute of Geography, the European Soil Bureau, the University of Manchester Institute of Landscape Ecology, MTT Agrifood Research Finland, and the Agricultural Research Institute Iceland have shared data and expertise in order to develop the Northern and Mid Latitude Soil Database (Cryosol Working Group, 2001). This database was the source of data for the current product. The spatial coverage of the Northern and Mid Latitude Soil Database is the polar and mid-latitude regions of the northern hemisphere: Alaska, Canada, Conterminous United States, Eurasia (except Italy), Greenland, Iceland, Kazakstan, Mexico, Mongolia, Italy, and Svalbard. The Northern and Mid Latitude Soil Database represents the proportion (percentage) of polygon encompassed by the dominant soil or nonsoil. Soils include turbels, orthels, histels, histosols, mollisols, vertisols, aridisols, andisols, entisols, spodosols, inceptisols (and hapludolls), alfisols (cryalf and udalf), natric great groups, aqu-suborders, glaciers, and rocklands. Also included are data on the circumpolar distribution of gelisols (turbels, orthels, and histels), and the ice content (low, medium, or high) of circumpolar soil materials (from the International Permafrost Association, 1997). The resulting maps show the dominant soil of the spatial polygon unless the polygon is over 90 percent rock or ice. Data are in the U.S. soil classification system and includes the distribution of soil types (%) within a map unit (polygon). Data are available in ESRI shapefile format and ESRI interchange file format and include the same attribute values with the exception of Italy, which does not contain distribution values.

美国农业部、加拿大农业与农业食品部、俄罗斯农业科学院、哥本哈根大学地理研究所、欧洲土壤局、曼彻斯特大学景观生态研究所、芬兰MTT农业食品研究所以及冰岛农业研究所共享数据与专业技术知识，共同构建了北中纬度土壤数据库（Northern and Mid Latitude Soil Database，冻土工作组（Cryosol Working Group），2001）。本数据集的原始数据即源自该数据库。北中纬度土壤数据库的空间覆盖范围涵盖北半球极地与中纬度区域，包括阿拉斯加、加拿大、美国本土、欧亚大陆（不含意大利）、格陵兰、冰岛、哈萨克斯坦、墨西哥、蒙古国、意大利以及斯瓦尔巴群岛。该数据库记录了各空间多边形（制图单元）中优势土壤或非土壤类型的占比（百分比），其所涵盖的土壤类型包括冻融冻土亚纲（Turbels）、正常冻土亚纲（Orthels）、有机冻土亚纲（Histels）、有机土（Histosols）、软土（Mollisols）、变性土（Vertisols）、旱成土（Aridisols）、火山灰土（Andisols）、新成土（Entisols）、灰化土（Spodosols）、始成土（Inceptisols，包含hapludolls）、淋溶土（Alfisols，包含cryalf与udalf）、钠质土类（Natric great groups）、水成亚纲（Aqu-suborders）、冰川以及裸岩区。此外，数据库还包含永冻土土纲（Gelisols，涵盖冻融冻土亚纲、正常冻土亚纲与有机冻土亚纲）的环极分布数据，以及环极土壤物质的含冰量等级（低、中、高）数据，数据源自国际冻土协会（International Permafrost Association，1997）。生成的专题地图将展示各空间多边形的优势土壤类型，但若多边形区域内裸岩或冰体占比超过90%，则不展示具体土壤类型。本数据集采用美国土壤分类体系，记录了各制图单元（空间多边形）内各类土壤类型的占比（%）。数据可通过ESRI形状文件（ESRI shapefile）与ESRI交换文件格式（ESRI interchange file format）获取，两类文件包含的属性字段基本一致，仅意大利区域未提供土壤类型分布占比数据。