Friday, July 5, 2013

The Sylvania Wilderness of Michigan

The Sylvania Wilderness in the Upper Peninsula of Michigan has 34 pristine lakes which can be explored via a trail network or by kayak or canoe.  During a week-long trip to Michigan with my parents, we liked this area so much we kept coming back day after day.
The clear waters of Clark Lake.
Sylvania is remarkable because it has one of only three old-growth forests in the Great Lakes Region.  The forest here feels primeval- with large trees and an open understory dotted with wetlands, and rich with moss, fungi, and ferns.  The paleoecology and patch dynamics of this forest have been the subject of some fascinating research- more on that before the hike details, since I thought it was so cool to learn about. 
Rotting log with polypore mushroom (Ganoderma tsugae, the hemlock varnish shelf fungi).
The hemlock-hardwood old-growth forest
It's not just the ages of the trees that are old at Sylvania.  This forest community (i.e. the types of plants and their interactions) has been around for thousands of years.  Scientists can look back in time using pollen cores and fossils to reconstruct the history of plant invasions and extinctions, and to determine forest species composition over time.  9700 years ago, Sylvania used to be predominately black spruce forest, but this was replaced by pine and red oak and maple, and then the hemlocks invaded the area 3100 years ago (Davis et al. 1998).  If you are in a grove of hemlock in Sylvania, chances are there have been hemlock there for at least a thousand years.
Hemlocks along the shore of High Lake.
Old-growth forests of Sylvania are a mosaic of either predominately hemlock or predominately sugar maple patches.   We noticed this on our hikes- the Clark Lake area had many hemlock patches, and the forest around the Bear Lakes was brighter and had more maple.  Forest patches are maintained because each of these competitors have seedlings that do well under the parental tree types- baby hemlocks need the rotting hemlock nurse logs, while baby maples do well in maple forests where they get enough sunlight in spring.  It was neat to see the contrast and understand why the trees are patchy rather than all mixed up.

Eastern hemlock-hardwood forests used to be one of the most abundant forest types, but are now restricted to 0.2% of their original range and the hemlocks are at risk.  The hemlocks of Sylvania appear huge and healthy, but their numbers are decreasing in Sylvania due to deer overpopulation and invasive earthworms (Salk et al. 2011).  In the southeast where I normally hike, hemlocks have been devistated by the invasive wooly adgeldid, but this pest hasn't reached the Upper Peninsula.  Its sad that hemlocks, which I think are such beautiful trees, are threatened in so many areas for different reasons.

Clark Lake loop hike
The Clark Lake loop goes around it's namesake lake through some marvelous hemlock stands and makes for a great dayhike.  Some websites say it's only 7 miles but others say 8 or 9 miles.  By my reckoning, it was definitely on the longer side though it was mostly flat.

After paying the park fee, we set off from the trailhead near the swimming beach going counterclockwise around the lake.  Blue-blazes were intermittent, and side trials were confusing so we were glad to have picked up extra maps from the ranger station.  There were fewer campsites on the western bank where the trail was more rutted and muddy.
A refreshing dip in Clark Lake.
East Bear Lake, West Bear Lake, and High Lake
The following day, we began our hike from the signed trailhead at the northeastern side of the park on FS 6320.  There were no blazes or trail markings, and trails were often faint.  Campsites were (sometimes) marked from the lakeshore side, reflecting fact that most people access this wilderness by kayak or canoe.

Mosquitoes were thicker than I'd ever encountered anywhere.  But we got to watch a loon float on the dazzling turquoise clear waters of High Lake.
Overgrown path to High Lake.
Crooked Lake and Katherine Lakes
We also did another short hike starting from the trailhead east of the Sylvania Entrance Station but before the boat landing for Crooked Lake.  This unblazed trail followed an old roadbed south through both types of old growth forest.  Turnoffs to both lakes were not signed.  The rain didn't seem to have any impact on the mosquitoes which were relentless.
Katherine Lake.
For more information:

Friends of Sylvania-information for visitors, natural history, maps, and how to help protect Sylvania.

Check out this awesome paleoclimate animation by clicking on the map and then selecting a species (try Tsuga/ hemlock).

Davis, M. B., R. R. Calcote, S. Sugita, and H. Takahara. 1998. Patchy invasion and the origin of a hemlock-hardwoods forest mosaic.  Ecology 79: 2641-2659.

Salk et al. 2011.  Poor Recruitment is changing the structure and species composition of an old-growth hemlock-hardwood forest.  Forest Ecology and Management 261: 1998-2006.

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