Distribution And Abundance Of Invasive Nonindigenous Plants And Rare Plants At Two Riverine National Parks In The Great Lakes Network PDF Download

Anthropogenically driven environmental changes have led to far-reaching ecological changes across the globe. Development and land-use change have caused increased habitat loss and fragmentation and altered ecosystem processes, thereby threatening biodiversity and the provision of ecosystem services. Further, disturbance regimes are shifting away from those that led to the development of contemporary plant assemblages. Over the past two centuries in the Great Lakes Region, plant communities have experienced unprecedented rates of change reflecting logging, land use change, fire suppression, overabundant ungulates, and climate change. My goal was to develop a deeper understanding of the mechanisms of forest change in the Great Lakes Region by focusing successively on the past, present, and future. I first evaluated shifts in forest composition across nine national parks between presettlement (1850s-1880s) and modern times (2008-2014). I next explored how plant functional traits moderate species responses to deer herbivory, soils, and light availability. Finally, I modeled species ranges to predict whether or not projected future climate conditions will be suitable for 30 common understory plants in the parks. Forests in Great Lakes national parks have shifted substantially since the 1800s. Preferred timber species like Pinus strobus and Tsuga canadensis and fire-adapted species like Quercus macrocarpa and Pinus banksiana have declined while aspen (Populus spp.) and maple (Acer spp.) have increased. These changes are associated with ongoing recovery from the Great Cutover, fire suppression, mesophication, and ungulate herbivory. Understory plant community composition shifted considerably following 10-15 years of deer exclusion, and these changes are determined, in part, by functional traits. Species responses to soil conditions and light availability also depend on plant functional traits, namely their mode of pollination, leaf dry matter content, and their habitat specificity. Future climates in the Great Lakes national parks are unlikely to support the currently dominant understory species. If these plants cannot adapt to climate change in place, plant communities in these national parks will continue to change in species composition as they respond to shifting climates. These regional shifts reflect challenges that plant communities around the world face as they respond to shifts in land-use, herbivory, and climate change.