Changes on the land
Ecosystem Preserve celebrates 25 years of education and inspiration

Forest

In 1938, the first aerial land survey was conducted in the state of Michigan. Early survey photos of the area now occupied by the Ecosystem Preserve show a land-use configuration common for the time, a woodland and wetland complex surrounded by small, varied agricultural fields. The woodland shows numerous irregular openings indicative of selective cutting for firewood or timber. Surrounding farmland supported vegetable production, row crops, hayfields and orchards.

Photos taken 30 years later indicate significant land-use changes after World War II. On more than half of the land, farming had given way to residential development or inactivity, and on the remainder many small and diverse fields had been consolidated into corn production on what became known as the “Kelly farm.” During the same period, harvest of what would be the preserve woodlot apparently stopped, and the many canopy gaps began to close. Later photos record the last corn production in the fields around the preserve’s woodlot in 1985, the creep of woodland into abandoned farm fields, and the progressive maturing of the forest canopy. One year after the last corn was harvested on these lands, Calvin College purchased the Kelly farm, and the former cornfields became part of the preserve.

In the early 1970s changes in the preserve forest intrigued Alan Gebben of the Calvin biology department, and in the summer of 1974 he and then-student John Ubels (now himself a Calvin biology professor) mapped and measured every tree larger than 2 inches in diameter in the 10-acre woodlot. Their survey revealed that although the woodlot had never been plowed or completely cut over, years of cutting had produced a mix of trees quite unlike what might have been expected in the absence of disturbance. Since 1984, at five-year intervals, preserve personnel have repeated this survey. Data from the surveys now document the history of more than 1,000 trees over a 35-year span. In broad stroke, the data show that the woodlot is slowly trending toward the forest type expected in this area, beech-sugar maple forest, but many vestiges of the wood harvest period will persist for decades.

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In one corner of the woodlot, for example, stands a loose group of red oaks whose ages span at least four oak generations. Since it is well documented that red oak seedlings do not succeed in shade, it appears that trees of each generation developed during a unique canopy gap that subsequently closed. The oldest of this group fell nearly 30 years ago; 10 years later another was killed by lightning. These losses thinned the canopy, but not enough to allow in another oak generation. The seedlings growing beneath the remaining oaks belong to other species.

Around the preserve margins old cornfields are now passing into woodland. By comparison the old forest matures slowly. Change occurs by countless small replacements, and by persistent and careful observation; we hope to mark these changes and come to better understand the forces that shape them.               

—Randy Van Dragt, Ecosystem Preserve director