Although the initial response to salvage (also known as, post-disturbance or sanitary) logging is known to vary among system components, little is known about longer term forest recovery. We examine forest overstory, understory, soil, and microtopographic response 25 years after a 1977 severe wind disturbance on the Flambeau River State Forest in Wisconsin, USA, a portion of which was salvage logged. Within this former old-growth hemlock-northern hardwoods forest, tree dominance has shifted from Eastern hemlock (Tsuga canadensis) to broad-leaf deciduous species (Ulmus americana, Acer saccharum, Tilia americana, Populus tremuloides, and Betula alleghaniensis) in both the salvaged and unsalvaged areas. While the biological legacies of pre-disturbance seedlings, saplings, and mature trees were initially more abundant in the unsalvaged area, regeneration through root suckers and stump sprouts was common in both areas. After 25 years, tree basal area, sapling density, shrub layer density, and seedling cover had converged between unsalvaged and salvaged areas. In contrast, understory herb communities differed between salvaged and unsalvaged forest, with salvaged forest containing significantly higher understory herb richness and cover, and greater dominance of species benefiting from disturbance, especially Solidago species. Soil bulk density, pH, organic carbon content, and organic nitrogen content were also significantly higher in the salvaged area. The structural legacy of tip-up microtopography remains more pronounced in the unsalvaged area, with significantly taller tip-up mounds and deeper pits. Mosses and some forest herbs, including Athyrium filix-femina and Hydrophyllum virginianum, showed strong positive responses to this tip-up microrelief, highlighting the importance of these structural legacies for understory biodiversity. In sum, although the pathways of recovery differed, this forest appeared to be as resilient to the compound disturbances of windthrow plus salvage logging as to wind disturbance alone, by most vegetative measures.
Bibliographical noteFunding Information:
Funding for this project was provided by the U.S. Federal McIntire-Stennis Funds , Iowa State University , and the U.S. Geological Survey . G.R. Guntenspergen also acknowledges the support of a Sigma Xi Grant-In-Aid of Research that initiated this study in 1979 and support from the National Geographic Society and the American Philosophical Society to continue the long-term monitoring at this site. We thank T. Anderson for assistance in the field work, M.J. Burkgren for soil sample preparation, L. Burras for assistance with and advice on soil analysis, C. Mabry McMullen for assistance in analyzing understory herb data, P. Caragea for statistical advice, and R. Atwell and especially C. Peterson for comments on the manuscript. C.P. Dunn and J. Dorney were instrumental in helping to establish permanent plots in 1979.
- Flambeau River
- Forest recovery
- Post-disturbance logging
- Sanitary logging