Abstract

The relationship between treeline position and field-layer diversity in the central Norwegian Mountains is examined by the use of multivariate techniques. Species and environmental data from altitudinal transects across the entire forest-tundra ecotone and various altitudinal partitions are analysed. The main variation in the species data show positive correspondence with altitude and distance to treeline and forest line and negative correspondence with factors related to the structure and presence of a tree cover. Distance to the treeline explained most of the variance in species distribution and most distribution boundaries are found in the vicinity of the treeline. Topography is an apparent factor only in a zone just above the treeline, and there is no correspondence between species occurrence and altitude in this zone. The importance of aspect is only evident at high altitudes, where plant communities are most exposed to abiotic environmental factors. Descending tree communities during the Holocene have produced plant communities above the present treeline that still are dependent on environmental conditions previously provided by the forest. Under present alpine conditions the main structuring force for vegetation composition is changed from being mainly biotic to abiotic. The long-term inertia of the field-layer composition across the forest-tundra ecotone is important to consider when making predictions of future responses of the ecotone

Published in

Écoscience
2002, volume: 9, number: 3, pages: 375-385
Publisher: UNIVERSITE LAVAL

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