Subalpine forests: a world perspective with emphasis on western North America

This paper represents an attempt to outline the general characteristics of the biota and some common abiotic features of subalpine forests in the northern hemisphere. We emphasize North American, temperate, subalpine forests and compare these to subalpine forests occurring between 30 and 60°N latitude in Europe and Asia. The northern hemisphere limit is based on the biogeographic history of the Earth. Because conifer evolution occurred primarily after the first division of Pangea (Daubenmire, 1978), modem conifer genera are generally restricted to either the northern (e.g., Abies, Picea and Pinus) or southern hemisphere (e.g., Podocarpus and Dacrydium), albeit with wide distributions within their respective hemispheres. Consequently, the two hemispheres lack forests composed of closely related genera. The three northern genera, plus Tsuga and Larix, commonly occur as dominants in temperate North America, Europe and Asia (Figure 1 a) and form forests that are physiognomically similar across all three continents. In fact, the tree, shrub and herb strata of northern hemisphere conifer forests contain many common genera of plants and animals