Memorial Grove is just north of State Highway 70 in Wisconsin. It's dedicated to four local Forest Service employees who didn't return from the Second World War, but it's also a living memorial to the great trees that once towered over the lake country. By accident or luck, 47 acres here were never cut, and the eldest hemlock checks in at a hoary 320 years. On a gray January morning, Tom Rooney tramps about on a thin crust of snow, surveying the forest floor. "Lots of maple seedlings," he says, "but there are hardly any hemlock."
As a postdoctoral botanist with the University of Wisconsin, Rooney has studied hemlock regeneration at more than 100 sites. "We lost a lot of hemlock during the wave of logging," he says, referring to the Paul Bunyan era at the turn of the last century. "Now we're losing the remaining ones to browsing." He singles out a small maple as thick as a soda straw and less than two feet tall. All about the stem, shoots have been clipped off, their growth redirected by precise dentition— bites. "We don't know what the browsing is like, but the plants sure know."
When a tree begins to die, it can take years before anyone notices; forests can hide their decline for decades. Seeds fail, saplings wither, young trees don't make the vault to the canopy. Eventually the last survivor from a once-mighty stand reaches the end and casts a final seed. Standing before a hemlock seedling about three feet tall, Rooney parses its branches with gloved hands. "A lot of the lower branches appear to be browse-damaged," he says. "You have needles coming off the main stem, which indicates the plant is stressed, so it is getting eaten periodically." The usual suspects: deer.
Fifty years ago, botanist John T. Curtis of the University of Wisconsin orchestrated a massive reconnaissance of the state's plant communities. He then put it all together in a book, The Vegetation of Wisconsin, which established a benchmark. In 2000 and 2001, Rooney and his boss, botanist Don Waller, revisited 67 of Curtis's northern plots. Of the 62 sites still undeveloped, the most changed were in two state parks where deer hunting is not permitted: Lake Gogebic in Michigan and Brunet Island in Wisconsin. Both lost 75 percent of their species between 1950 and 2000, and sites across the board showed dramatic declines. On average, Waller and his team found almost 20 percent fewer species than Curtis had 50 years before, although they sampled the same sites much more intensively.
