Forest change in the Driftless Area of the Midwest: From a preferred to undesirable future

Abstract

In the midwestern and eastern U.S., oaks (Quercus spp.) have been a dominant component of forests for at least the last 10,000 years, providing vital habitat for numerous wildlife and plant species that have adapted to oak forest conditions. However, the current state of these oak systems, in which there has been a general lack of successful oak regeneration and recruitment and an increase in the relative dominance of mesophytic species, may be nearing critical thresholds. If reached, restoring oak systems through natural regeneration and other methods, such as prescribed fire, may become especially challenging if not impossible. An understanding of spatial variation in oak dominance over time can inform and potentially improve the efficacy of intervention strategies. Using Public Land Survey and Forest Inventory and Analysis (FIA) inventories, we evaluated changes in the composition of timberland across ecoregional subsections in the Driftless Area of the Midwest at three time periods (pre-settlement 1800s, 1990s, and 2000s). We identified an overall decrease in oak dominance, and particularly dominance of the white oak (Quercus alba L., Q. macrocarpa Michx., and Q. bicolor Willd.) species group since the presettlement era, and an increase in other eastern soft hardwoods. Within the last 20 years, both the red oak (Q. rubra L., Q. ellipsoidalis E.J. Hill and Q. velutina Lam.) and white oak species groups decreased in dominance, with an increase in hard maple-basswood (A. saccharum Marsh., A. nigra L., and Tilia americana L.) species group dominance, indicating further mesophication of forests in the region. However, we found a notable decrease in hard maple-basswood relative dominance within the small diameter class across most of the regions within the last 10-20 years, with an increase in dominance of other, non-oak, species. Our findings complement qualitative evidence from interviews with natural resource professionals from the region and offer further information on the potential for forest conversion to ''undesirable'' forest conditions, as identified as a source of concern by some professionals. There was spatial variation in these trends, however, with some pronounced differences across adjacent state boundaries. The variation in forest change across state boundaries suggests the role of state-level socioeconomic and policy factors in affecting forest conditions, and thus the potential for a targeted and timely approach to promoting preferred pathways of change. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. a b s t r a c tIn the midwestern and eastern U.S., oaks (Quercus spp.) have been a dominant component of forests for at least the last 10,000 years, providing vital habitat for numerous wildlife and plant species that have adapted to oak forest conditions. However, the current state of these oak systems, in which there has been a general lack of successful oak reg...

Post‐settlement ecological changes in the forests of the Great Lakes National Parks

“…We also found a 7% increase in box elder RBA at Mississippi, similar to that found throughout the Driftless Area of the Midwest (Knoot et al. ).…”

Landscape-fire relationships inferred from bearing trees in Minnesota

“…Our products build on and complement past research by providing a ner-scale depiction of presettlement re settings. e pyrophilic percentage maps corroborate the conclusion that re was the preeminent force in the Midwest Broadleaf Forest Province, as expressed in the literature (Cottam 1949, Curtis 1959, Grimm 1984, Hanberry et al 2012b, Knoot et al 2015, Peters 1978. Located between the highly ammable prairie (Province 251) and the less ammable conifer-northern hardwoods (Province 212), the Midwest Broadleaf Forest Province was a transition zone resulting from high-frequency surface burns estimated at every 5-30 years (Wheeler et al 1992).…”

Putting Russia on the genome map

“…Surprisingly, Millar and Stephenson hold up northern mid-successional oak-hardwood forests of the eastern and central United States as models of "resilient" forests capable of sustaining structure, function, and services. In fact, these forests are undergoing rapid changes in composition and structure, losing diversity and the ability to regenerate key species (3)(4)(5)(6). These changes reflect responses to many drivers, including habitat fragmentation, ungulate browsing, and exotic species invasions, all of which threaten ecosystem services just as observed in western forests (7)(8)(9).…”