(1786-1859)
The first known scientist to study plant life at the Straits of Mackinac was Thomas Nuttall. Hitching a ride from Detroit in a birchbark canoe, Nuttall landed at Mackinac Island on August 12, 1810. During his journey, the English botanist documented 60 species of plants in the Upper Great Lakes, about 20 of which had not previously been described for science.
Over the past two centuries, dozens of amateur and professional botanists have made similar journeys. To date, about 600 species of wild plants have been identified on Mackinac Island, including 270 wildflowers.
Summary of Surveys
Plant studies over the years have taken various forms, many creating inventory lists of species. Henry David Thoreau, for example, botanized on Mackinac Island for six days in July 1861. Accompanied by Horace Mann Jr., the pair compiled the most complete list to date, cataloging about 30 species of trees and shrubs and over 75 herbaceous plants. Of those, 27 were noted as “weeds” or introduced, non-native species.
For many years, it was assumed Thoreau’s note of lilacs was the first written report of the fragrant ornamental on the island. In recent years, however, earlier articles have pushed this date back to the mid-1840s. Currently, the oldest record belongs to a correspondent of the Boston Post identified only as “J.I.M.” Dated June 18, 1845, his letter described Mackinac Island’s “clear air, sweetened by the lilac and apple trees but just in blossom…”
Two botanists deserve special credit for creating the most comprehensive inventories. In 1913, University of Michigan professor Charles K. Dodge published the report, “The Flowering Plants, Ferns, and their Allies of Mackinac Island.” His paper identified 415 total species, including 60 introduced varieties. More than 80 years later, island resident Patricia L. Martin documented 560 plants while earning her master’s in botany from Central Michigan University. Her report, “A Floristic Study of the Vascular Plants of Mackinac Island, Michigan,” included 160 non-native species, 91 of which had previously been unreported.
Quadrats Galore
John E. Potzger, head of the Botany Department at Butler University, studied Mackinac flora between 1934–1936. Potzger’s work differed from most other botanical surveys on the island. The curious professor sought to scientifically document plant distribution in several target areas, comparing a lowland perimeter zone with hardwoods in the island’s interior. His work included soil acidity tests, strip transects, and quadrat work to determine density, frequency, and fidelity of species. His report, “The Vegetation of Mackinac Island, Michigan: An Ecological Survey,” was published in March 1941.
Three decades later, Edwin A. Phillips, of Pomona College, revisited woodlands which had been surveyed by Potzger, seeking to replicate portions of the former study. Published in 1976, his report noted, “The present general appearance of the vegetation is of a fringe circle of coniferous trees with hardwood forests in the higher center of the island, much as they appeared to Potzger.” In upland areas, he observed an increase in American beech, while northern white cedar continued to dominate the lower island periphery.
Hardwood Forest Survey (v.2025)
This summer, Makayla Shirey, natural resources intern for Mackinac State Historic Parks, is replicating a portion of the Potzger/Phillips survey. Focusing on the island’s upland hardwoods, her work will include laying out 100 meter square quadrats (10 meters per side) and counting trees growing within. The goal will be to survey five stands of five units each, for a total area of 2,500m2. Her collected data will provide a rare opportunity to examine the same deciduous woodland which was studied both 50 and 90 years ago. The 2025 study will only include stands of hardwood trees (conifers may be part of a future project).
Since 2000, Mackinac Island forests have been dramatically impacted by new invasive threats including emerald ash borer and beech bark disease. This has led to widespread mortality of these climax species, especially in deciduous forests of the island’s interior. Aggressive invasive plants, including Norway Maple, buckthorn, and honeysuckle, combined with a changing climate, have also affected island ecosystems over the past quarter-century.
This survey will assist MSHP as we strive to preserve and protect Mackinac’s rich historical and natural resources for future generations. This autumn, we’ll share a report of the season’s work and what it tells us about the current status of the island’s hardwood forests. To learn more about the island’s “wild side,” pick up a copy of Wonders of Mackinac: A Natural History of Mackinac Island at any MSHP store during your next visit.
