MULTI-SCALE ANALYSIS OF SOIL NUTRIENTS AT ALPINE TREELINE IN GLACIER NATIONAL PARK, MONTANA

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Abstract
Alpine treeline is the transition zone between lower-elevation forest and higher-elevation tundra vegetation. This ecotone varies from being a straight abrupt boundary to one that is highly fragmented. This paper examines the heterogeneity of the edaphic environment at alpine treeline to determine if differences exist in the nutrient status (i.e., carbon, nitrogen, phosphorus, and potassium) of soils underlying tundra and arboreal vegetation. Data analysis is based on samples from four intensively sampled treeline locations, and is performed at three different scales: regional, inter-basin, and intra-basin. Each scale represents a different level of data aggregation. At the regional level, krummholz and tundra soils differ only with regard to nitrogen and carbon. At finer scales, differences are evident between krummholz and tundra soils for all nutrients tested. The greatest differences between krummholz and tundra soil nutrients occur at the more xeric treeline sites. Heterogeneity of the edaphic environment has the potential to structure treeline response to climate change. [Key words: alpine treeline, sub-alpine forest, tundra, soil nutrients, Glacier National Park (CNP), Montana.]