Kalamazoo Erosion seen as key to clay bluff habitat Area to be added to list of state's unusual ecosystems

By Rosemary Parker

Kalamazoo Gazette

SOUTH HAVEN, Mich. (AP) -- It's a rare treasure shaped by time and the scorching sun, howling winds and constant drip of water nearly as alkaline as baking soda.

The vertical cliffs of the Wau-Ke-Na Preserve, located along the Lake Michigan shoreline between South Haven and Saugatuck, are one of Michigan's few examples of a rare environmental classification known as clay-seepage bluffs.

And now that its features are better understood, the area is in line to be added to the Michigan Natural Features Inventory, a list of the state's unusual native plants, animals, aquatic animals and natural ecosystems.

A team of scientists recently visited the preserve to document the 127-acre site's rare soils, plants and continuous trickle of alkaline water.

They found a stunning array of rare wildflowers, trees and grasses -- all clinging to the near vertical surfaces of the bluffs where it seems impossible that anything could grow.

"They are very unique sites, and each one is like a surprise," said Josh Cohen, an ecologist with the project. "We don't have a classification of the clay-bluff type. We hope to include that natural community in the near future."

Cohen said the Wau-Ke-Na Preserve is one of only a handful of areas in the state where this harsh, beautiful terrain is found. Wisconsin has one such area on its side of Lake Michigan; others are found at the east end of the Lake Superior lakeshore's Pictured Rocks and at the west end of the Porcupine Mountains, also in the Upper Peninsula.

Cohen and botanist Mike Penskar last month made their first visit to the Wau-Ke-Na Preserve, where scientists are just beginning to uncover the features of this environmental jewel.

"In early September, the bluff face is purple with fringed gentian and blue lobelia," said Nate Fuller, conservation and stewardship director for the Southwest Michigan Land Conservancy.

The preserve was bequeathed to the conservancy in 2005 by William Erby Smith. The property surrounds a private lakeshore home, which is on the market for $2.28 million.

Plants found on the bluffs are those normally associated with inland fens, which are pockets of mineral-rich wetlands.

Fuller said it is difficult to understand how such plants survive in this extremely harsh environment.

"Incredibly hot sun bakes the clay, and it goes through freezes and thaws in the winter and during storm events and experiences continual weeping of the alkaline groundwater that drips down the face of the bluffs," he said.

In years when soils are saturated with groundwater, the hard clay softens and a windy day may be enough to topple trees and cause the ground to suddenly give way in "slumps," which wash the whole face of the bluff down to the shore.

A new cliff face then is exposed -- appearing as a barren clump of clay seemingly unable to sustain plants at all. But slowly the plants begin to re-emerge, working their way back up to again blanket the cliff.

Wildly out-of-place tree species, typically found in the Upper Peninsula, also have found a home on the cliffs, Fuller said.

"Trees like mountain ash and white cedar are typically found farther north," Fuller said. "White cedar in southern Michigan usually can only be found in cold springs and bogs. But there are stretches along the clay bluffs where it is the dominant tree, a situation you'd expect to see in the U.P., not just north of South Haven."

Elsewhere in the state, Fuller said, "Mountain ash doesn't become a common tree until you hit the Mackinac Bridge. But in these sites, we have mountain ash growing next to tulip trees, a southern tree species that is at the northern edge of its range -- something that the Michigan Natural Features Inventory scientists thought was extraordinary."

Fuller said scientists are still "wrapping our heads around it."

They believe that just as the fen communities inland depend on either fire or beaver-dam flooding to keep them open and drive back invading trees and shrubs, or as prairies depend on occasional fires, the plants on the clay bluffs need regular erosion to keep them from being crowded out.

It runs counter to the conventional wisdom that erosion is bad, Fuller said.

"These systems are designed to slump, designed to erode," he said.

In addition to giving a competitive edge to rare plant species, the process also produces an ever-changing landscape.

"It's pretty unpredictable what a portion of the bluff is going to do," Fuller said. "You go out and it's a brand new place."

Published: Thu, Oct 27, 2011