April showers brought May flowers, and likely June Mosquitos

Spring Ephemerals and Forest Ecology
 
Rouge Park has just wrapped up its spectacular spring ephemeral flower season, though a few late blooms still dot the forest floor. The term ephemeral comes from the Greek word ephemeros, meaning “lasting only one day.” In modern English, it refers to anything short-lived like these special spring wildflowers. From sprouting to flowering, pollination, and senescence (think of the changes plants go through in fall), most of these flowers complete their life cycle within a few weeks, all before the tree canopy fully leaves out. Some species, like Virginia waterleaf, are just now blooming, while a few, such as violets, linger through the summer.
Interestingly, 30–40% of spring ephemerals disperse their seeds through a process called myrmecochory, where ants play a key role in seed distribution. These plants produce seeds with fatty appendages called elaiosomes (pronounced el-eye-o-zome), which ants collect and carry underground. The ants consume the fatty part, and the seed is left safely buried, protected from predators like slugs and mice. This symbiotic or mutually beneficial relationship helps ensure the next generation of wildflowers thrive.

While the spring flowers fade, the forest canopy has now filled in. Like farmers, trees also wait for the danger of late frost to pass before leafing out. In Southeast Michigan, the last frost date typically falls in early to mid-May, although climate change has made this timing more unpredictable. That’s why trees like oaks, ashes, black walnuts, hickories, and black locusts are among the last to leaf out. These first and last frost dates are so important for farm planning that the USDA has developed a number system called the hardiness zones to help farmers and horticulturalists plan. These zones have shifted in recent years. Meanwhile, the seeds of early bloomers, such as maples, have already spun to the ground in the form of winged samaras (yes, the “helicopters,” they’re even edible!). Invasive honeysuckles have nearly finished blooming too. Truly, many a May flower has come and gone!

A Tale of Two Forests

Much of Rouge Park’s southern section (south of Tireman Avenue) remains a hidden gem within Detroit. This area includes our sugarbush, the future site of the restored Ma'iingan Wildwood Trail, and our vernal pond monitoring area, where we host spring ephemeral wildflower walks. Many parts of this region lie in a natural floodplain that has never been clear-cut, resulting in a forest rich in native plant diversity and old-growth characteristics.
In contrast, the forests around the mountain bike trail were historically cleared for agriculture and grazing. These disturbed areas now host dense stands of invasive species like honeysuckle and buckthorn. To the untrained eye, it might seem lush and full of life. But in healthy, mature forests, the canopy is so dense that the forest floor stays relatively open, with few invasive plants and more diverse native understory species.

Think of an ancient prairie turned farm field, years of tilling disrupt plant diversity but remnants might survive along the edges where machinery didn’t reach. That’s often the case for Rouge Park’s prairie areas. When restoration is attempted using retail seed stock, only a narrow range of species returns. This is why forest forensics, the study of clues in the landscape, can help us understand historical land use and guide restoration efforts. (Look out for our Forest Forensics Hike this fall!).

Vernal Ponds: Hidden Wetland Wonders

One of the most exciting ways to assess forest health is through community science, such as vernal pond monitoring. Vernal ponds are temporary spring wetlands that support a burst of life, particularly for amphibians and invertebrates because they are isolated from streams and lack fish predators.

This spring, students from Cody High School and Black to the Land’s Urban Forest School joined us in surveying the flora and fauna of our vernal ponds. We observed garter snakes, salamanders, toads, and a wide variety of plant species including:
Boxelder maple, carex sedges, American ginseng, meadow rue, Virginia creeper, cutleaf toothwort, mayapple, Dutchman’s breeches, bellworts and invasive species like garlic mustard and honeysuckle.

We also documented macroinvertebrates such as scuds, daphnia, rat-tailed maggots, water scavenger beetles, water tigers, and midge and mosquito larvae.

This monitoring effort feeds into the Vernal Ponds Partnership, part of the Michigan Natural Features Inventory, and helps us understand how these sensitive ecosystems are responding to climate change and human impact. We also made a strong push this season to remove invasive plants from the vernal pond area. With this year’s data as a benchmark, we’ll be able to track the success of our conservation work over time. ​