Sunday, July 15, 2012

Pearl King Savanna

Much of last week was devoted to working with the national meeting of the Botanical Society of America, which held their annual get-together in Columbus, Ohio. The event attracted about 1,000 attendees from all corners of America, and well beyond. Those of us involved in conservation often lament the seeming lack of recruitment of new blood, but there were plenty of of younger people at this botanical conference, which was nice to see.

Last Tuesday, I popped downtown to the Hyatt, site of the conference, and delivered a talk about Ohio's natural history, featuring many of the Buckeye State's best remaining places. On Thursday, I helped to lead a field trip to three of west-central Ohio's premier natural areas: Cedar Bog, Gallagher Fen State Nature Preserve, and the subject of this post, Pearl King Savanna.

A grove of stately giant oaks stand sentinel over a biologically rich remnant of the formerly vast Darby Plains prairie. The Darby Plains once sprawled over some 385 square miles, extending from Columbus's west side all the way to Mechanicsburg, about 30 miles to the west. Over 99% of this prairie has been converted to agriculture's Big Three (in this region): corn, soybeans, and wheat, or otherwise developed.

Prior to European settlement, savannas such as Pearl King would have dotted the Darby Plains. A savanna (not "Savannah"; that's a city in Georgia) is an open grove of trees underlain by herbaceous vegetation. In the case of Darby Plains savannas, the ground cover is a rich mixture of prairie plants. The trees are mostly oaks and hickories. Fire was, and is, an important factor in maintaining savanna plant communities. Regular scorchings eliminate non-savanna woody plant invaders, and encourage the specialized prairie grasses and other forbs that dominate the understory. The thick-barked oaks and hickories are impervious to the flames.

Pearl King Savanna in southwestern Madison County has been known to biologists for many decades as one of Ohio's last great oak savannas. The reason that Pearl King survived is due to the stewardship of its longtime owners, who were interested in this prairie relict and took care to protect it. In 2006, Franklin County Metroparks was able to acquire the site, ensuring that Pearl King lasts long into the future. We've had a good bit of luck with savannas of late, as Ohio's other great example, the Daughmer Savanna in Crawford County, was acquired by the Crawford County Park District last year.

The mammoth oaks and hickories in Pearl King have been around a long time, and many of them are probably nearing the end of their life cycles as living standing timber. The giant white oak in the foreground of the above photo toppled not long ago, and this tree probably dropped from its parent tree as an acorn before the American Revolution took place. Coring has revealed that some of Pearl King's colossal oaks are in the neighborhood of 350 years of age.

One of Metroparks' first steps upon taking ownership of Pearl King Savanna was to conduct a thorough tree inventory. They found that about 60 mature oaks and hickories still stood on the savanna's 14 acres, and identified another 120 much smaller saplings of prairie-appropriate tree species. Botanist Daniel Boone (yes, that's really his name), stands by a 15 foot tall bur oak, Quercus macrocarpa. Bur oak is the classic prairie savanna tree, and encouraging their recruitment is vital to long-term conservation of the savanna ecosystem.

Given enough time, that scrawny bur oak in the previous photo will grow into a monster 300+ year old behemoth such as the one that Dan is holding up in this photo. Such a tree was here to greet the first pioneers punching their way into the Darby Plains. Dan Boone made his first trip to Pearl King in 1983, and thus has a nearly 30 year history with this place. This tree would have been just as big at the time of his first visit, and would have been a notable specimen some 250 years prior, when the other Daniel Boone traipsed the Ohio and Kentucky frontiers.

The core savanna is 14 acres, and Metro Parks has added a six-acre buffer on the north and west sides. After planting these strips with seed stock harvested from other surviving bits of Darby Plains prairie, the buffers resemble a colorful moat full of prairie plants. A whorled rosinweed towers in the righthand side of the photo and the scene is awash in pink, purple, scarlet, and yellow courtesy of wild bergamot, purple coneflower, royal catchfly, and gray-headed coneflower.

Jutting hard up against the prairie is a sea of corn, and a massive bean field was just across the road. Once John Deere launched his steel chisel plow in 1837, the rich prairie turf was cut and planted to row crops with utterly astonishing speed. One of the greatest ecological tragedies, and losses of biodiversity in North America has been the demise of the tall grass prairie. Less than one percent of Ohio's original prairie remains, and the same is true of formerly prairie-rich states such as Illinois.

Our Botanical Society of America field trip attendees were like kids in a candy shop while exploring Pearl King Savanna. Most of them had never seen such a place. We spent about two hours in this 14-acre patch, and finally had to herd everyone back on the bus so that we might also have a bit of time at the other two field trip sites.

David Kriska of the Cleveland Museum of Natural History stands in a soft wispy sea of what is now one of our rarest prairie grasses, the prairie dropseed, Sporobolus heterlepis. He is looking at an even rarer Ohio plant, the plains frostweed, Crocanthemum (formerly Helianthemum) bicknellii.

Tony Reznicek of the University of Michigan was along on this foray, and he glanced down at one point to notice this rather undistinguished grass, well past its prime. It is weak speargrass, Poa languida, another rare Ohio plant and insofar as I know a new record for Pearl King.

Those of us interested in the conservation of Ohio's last great places can be grateful indeed that fabulous prairie remnants such as Pearl King Savanna are in good hands.

1 comment:

Brent C. Kryda said...

Very nice. Any idea on where to find a map of pre-settlement savanna coverage for eastern North America? I dare say that a good portion of Ohio, Michigan, southern Ontario, and even a bit of shoreline western New York and Pennsylvania consisted of savannas.