REPEAT PHOTOGRAPHY OF LAKE MICHIGAN COASTAL DUNES: EXPANSION OF VEGETATION AND HUMAN IMPACTS SINCE 1900

Coastal dunes are a prominent feature of the Lake Michigan shoreline, especially along the Lower Peninsula of the state of Michigan. The long-term geomorphic history of these dunes, which include large perched dunefields, has been researched in recent years, demonstrating how these systems respond to climatic variability and fluctuating lake levels. Less is known about how these dune systems change on shorter temporal scales. Using repeat photography, this paper attempts to demonstrate how the coastal dunes of Lake Michigan are changing in the historic record. Hundreds of photographs of coastal Lake Michigan dunes taken between the years 1885 and 2018 were collected from archives and citizen scientists. At over 60 of these locations in the spring and summer of 2019, we took new photographs replicating the original images. The changes between coastal dune conditions in the original photographs and in the 2019 re-photographs show a general conversion of bare sand dunes to vegetated dunes along the Lake Michigan shoreline. Human development has played a role in reshaping the coastal dune systems as well, but the most pronounced difference between historical dunes and current conditions is the advance of vegetation – grasses, shrubs, and even trees – at most locations where repeat photography was conducted. Here, we present the photograph pairs most representative of these changes and discuss likely causes, including the increase in precipitation in Michigan in the last 80-plus years.