Frigid Forests 'vs. Cryic Fields: Soil mperature Regimes of Two Different Cover Types in Aroostook County, Maine

摘要

The soil temperatures at a depth of 50 cm were recorded for four soils in Aroostook County, Maine from July 2001 to May 2006. The soils were located at two sites in Maine: Easton and Fort Kent. Each study site consisted of a forest soil with an intactO horizon and a field soil without an O horizon. All the soils had a mean annual soil temperature below 8°C, which olaces them in the domain of the cryic and frigid soil temperature regimes. The forest soils had an average mean summer soil temperatureof 11.5 and 10.2°C, while the field soils had an average mean summer soil temperature of 12.9 and 13.6°C. According to Soil Taxonomy, the forest soils have a frigid soil temperature regime, and the field soils have a cryic soil temperature regime. Thetwo adjacent soils should not have different soil temperature regimes based solely on cover type, and the criteria of Soil Taxonomy should be revised to correct this problem. The best proposal for the soils of Aroostook County. Maine would be to lower the mean summer soil temperature requirements for soils without an O horizon from 15 to 12°C, which would place all currently cryic field soils into the frigid soil temperature regime. This change goes against another proposal for revising the Soil Taxonomy criteria for the cryic and frigid soil temperature regimes. Any eventual revision to Soil Taxonomy will need to be based on many other studies similar to this one in other areas and will need to make sense on all frigid and cryic soils around the world.