Implementation of a long-term vegetation monitoring program at Isle Royale National Park: 2012 revision

Sanders, Suzanne; Grochowski, Jessica

We initiated a long-term vegetation monitoring program at Isle Royale National Park (ISRO) in summer 2010. The goals of this monitoring program are to detect forest change and to draw inferences about forest health so that management recommendations can be provided to Network parks. In 2010, we established 52 plots at ISRO, distributed among five forest types: balsam fir mixed, white spruce/trembling aspen mixed, paper birch mixed, eastern white cedar, and sugar maple/birch. While the cedar and the maple/birch forests on the west side of the island, and the fir forests on the east side appear to be mature, the paper birch and spruce/aspen types are transitioning. Red maple and black ash are replacing paper birch while balsam fir is replacing spruce and aspen. We found very little evidence of browse, either in the sapling/shrub layer or in the understory. It is unclear if the continued low density of moose on the island is contributing to this. Qualitative comparisons with a vegetation assessment from a 1910 visit suggest most change in the previous century has occurred in the shrub layer and understory. Taxus canadensis and Oplopanax horridus populations have become smaller, while three understory species not noted in the 1910 work are now common: Eurybia macrophylla (big-leaved aster), Polygala paucifolia (gay wings), and Streptopus lanceolatus var. roseus (twisted-stalk). We did note the presence of earthworms in at least two plots. This will adversely impact the understory in the coming decades. Park managers should acquaint themselves with expected impacts on both the overstory and understory assemblages as climate change advances. Adaptation strategies which promote resiliance, as well as facilitated adaptation techniques, may be needed to ensure the presence of stable species assemblages in the future.

Implementation of a long-term vegetation monitoring program at Isle Royale National Park: 2012 revision

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