Patterns and Processes of Tree Islands in Two Transitional Environments: Alpine Treeline and Bog Forest-Meadow Ecotones

Clusters of trees surrounded by a dissimilar type of vegetation are known as ‘tree islands’. Vegetation patterns at ecotones are often comprised of tree islands. Many studies, primarily from ecology and botany, have helped researchers understand tree islands from an ecological perspective. However, a look at tree islands in the context of pattern–process relationships helps to frame these important landscape features within a geographic perspective. At alpine treelines and bog forest‐meadow ecotones, tree islands are distinctive, finite, close to the environmental limits of trees, and relatively easy to observe. Therefore, they are interesting features with which to examine the effects of broader environmental change, and internal dynamics, such as positive plant interactions. In this article, we first broadly describe tree island patterns and their growth forms at the Cranberry Glades Botanical Area in West Virginia, and at alpine treelines of the North American Rocky Mountains. Internal and external factors that affect tree island distributions are then discussed. Finally, we examine how the fundamental similarities and contrasts between tree islands at treelines and bogs increase our understanding of broader environmental change, controls, and constraints.