Soil temperature and soil moisture characteristics for several habitat types of Montana and Idaho

Soil temperature and soil moisture data from sixty-six monitoring sites located in forest ecosystems of western Montana and northern Idaho were summarized. These data were analyzed in comparison to the criteria for soil temperature and soil moisture regimes (U.S.D.A.- Soil Taxonomy, Soils Staff, 1975). The hypothesis that climax forest communities (habitat types) occupy sites with characteristic soil temperature and moisture conditions was tested. The soil temperature and soil moisture status throughout the growing season for fifty-two monitoring sites was analyzed in respect to their climax forest series and habitat type class. The results of the analysis demonstrate that some forest habitat types of northern Idaho and western Montana occupy sites with a narrow range of soil temperature and soil moisture conditions; where as other habitat types have variable soil temperature and soil moisture conditions. The monitored soil temperature and soil moisture data were displayed for nineteen forest habitat types. Several relationships between climax forest vegetation, soil temperature regimes and soil moisture regimes were identified, for western Montana and northern Idaho. The Abies Iasiocarpa climax forest series monitoring sites classify primarily in the cryic soil temperature regime. The Thuja plicata, Abies grandis, and Pseudotsuga menziesii climax forest series monitoring sites classify primarily in the frigid soil temperature regime. In western Montana all the Abies lasiocarpa, Thuja plicata, and Abies grandis climax forest series monitoring sites classify in the udic soil moisture regime. The Pseudotsuga menziesii climax forest series monitoring sites classify in either a udic or a xeric soil moisture regime. It was concluded that a field soil scientist in western Montana or northern Idaho could estimate the soil temperature regime by knowing the climax forest series and elevation of a site. Discriminant analysis was applied to thirty-four monitoring sites representing six habitat types. The probability of the membership in a habitat type being correctly predicted by the site characteristics alone (i.e. average soil temperature, average soil moisture tension, and elevation) was eighty-six percent.