Franklin Savanna, Another Case Study in Ecosystem Collapse

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The collapse of a bur oak at Franklin Savanna being replaced by an encroaching buckthorn thicket and the shade of elms, Hill’s oaks, and black cherry

It was an old oak pasture that taught me about the great abundance of nature. We climbed those trees, or rather, when we crawled under the fence into Mr. Erickson’s pasture, walked right up onto their great, open-grown limbs. My first loves in nature—snakes, frogs, toads, and butterflies—lived among those oaks. Red-headed woodpeckers were our common woodpeckers. The smooth, cool feel of smooth green snakes is a cherished memory. Tiger salamanders greated us on damp April mornings. Blanchard’s cricket frogs crowded the muddy banks of the “crick.” We watched bats on warm summer evenings.

That was just a pasture in rural Iowa in the 1980s. A place that could have been or could be a savanna again, but also a place exploited for more than 100 years. Savannas, real savannas intact in their biota and core processes are something vanishingly rare.

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An area of true bur oak savanna at Kettle Moraine Oak Opening State Natural Area. Over the last decade or two, this site has been burned more years than not. This portion of the natural area is rare, in that encroaching woody vegetation was never so severe as to shade out and kill the lower limbs of the oaks or dramatically reduce the diversity or strutural integrity of the herbaceous vegetation (side note–herbaceous plants are no less important than oaks in savannas). Rare plants are here. Eastern hognose snakes are here; I know, because I accidentally stepped on one (I still feel really, really bad about that).

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This portion of Kettle Moraine Oak Opening State Natural Area experienced prior canopy closure and was once choked with invasive shrubs. After years of dedicated stewardship, this area is improving.

 

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Another true oak savanna, this one of mostly white oak, but also with some large northern red oaks and bur oaks, on private property on Lake Beulah. This site may have never been grazed, which is almost unheard of in this area and could explain why a few portions of it persisted in this condition without management. Elsewhere, maple, ironwood, ash, and bush honeysuckle did invade, but efforts are underway to to open the site up and promote the type of community seen here.

I walked Franklin Savanna State Natural Area in far southwestern Milwaukee County for the first time recently. I knew going in that it was going to be rough. Joshua Mayer on his State Natural Areas of Wisconsin blog said the following of the site:

“The great bur oaks bely the open environment that used to dominate this area, but there is virtually no evidence of a present-day savanna.  The natural area as presently constituted is basically a southern mesic forest with a creek and a few scattered opening filled with grasses.  There is no information found on Milwaukee County Park’s website, though they have a Natural Areas program.  A brief description can be found on the website of the Milwaukee Area Land Conservancy, but everything I have found suggests that this is a site that can be restored if funding is attained.  I have read that efforts are underway to restore the site, but as of fall 2016, I saw little evidence to that effect.  In the meantime, enjoy a stroll in a dense forest, but bring the bug spray!”

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This is one of those oaks. It’s lower limbs reached down to the ground before they died years ago.

It was obvious from a review of aerial photography going back to 1937 that Franklin Savanna had once been something much different, a fairly large tract of pastured and degraded prairie-savanna matrix studded with very large, open-grown oaks. At that time much of the uncultivated uplands in the southeastern Wisconsin landscape south of the vegetative tension zone were quite similar to this, generally mosaics of prairie, savanna, and oak woodland. Like much of the rest of that landscape, change since the middle of the last century has been dramatic, and the response has been tragically flat-footed.

As grazing ceased, suppressed woody vegetation was released in an environment where the integrity of the plant community and soil structure were likely impaired by years of high stocking rates. In southeastern Wisconsin, this generally occurred between 1960 and 1980, and coincided with a brief period of oak recruitment dominated by red oaks, particularly Hill’s oak. However, the real winners were shrubs, both native and exotic. The resulting canopy closure extirpated much of the native herbaceous vegation still present and closed the door on significant future oak regeneration. Relatively open sites were often invaded by bush honeysuckle early on, but most sites have subsequently been invaded by common buckthorn. Today, these sites typically consist of a declining overstory of mostly bur and/or white oaks, lower limbs long shaded and killed; a younger overstory of younger red oaks (Hill’s, northern red, and black), American elm, and black cherry; a shrub layer dominated by common buckthorn, or perhaps prickly ash under lucky circumstances; and a sparse herbaceous layer with an over-representaltion of species with easily-dispersed, stick-tight seeds like white avens, common agrimony, and stickseed. With this transition, the open landscape vanished, deer ticks became locally abundant, biting flies and mosquitos found new cover, and the whip-poor-will and the red-headed woodpecker lifted themselves by the seats of their pants and flew away, ceding their territory to the birds of closed forests.

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One of many remaining ancient, open grown bur oaks stands among dense buckhorn at Franklin Savanna. The number and presence of these trees can only be appreciated in winter after the leaves have fallen from the dense thicket. The lower limbs are lost, but this tree could probably be saved for decades to come.

Is Franklin Savanna a savanna?

Most of the open-grown trees are there in various states of decline, which could play out over a few years, decades, or more than a century. A few have already collapsed. Hill’s oaks stand shoulder to shoulder in places, still supporting native insects and the forest birds that forage on them, while at the same time hastening the decline of giant bur and white oaks and making future outbreaks of oak wilt extremely likely. There were once smooth green snakes here. Will I see them again? Tiger salamanders remain. They inhabit open prairies, savannas, and forests, so their persistence is not surprising, though toxic buckthorn leaf litter is a threat.

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A young bur oak, which likely got its start after grazing ceased in the middle 1900s (a light-starved bur oak tree this diameter on our property was 50 years old). It could not keep up with the buckthorn, black cherry, elm, and Hill’s oak.

Is it an oak woodland, something perhaps as rare or rarer than oak savanna?

Oak woodlands were diverse and likely stable over centuries, with open understories shaped by frequent, low-intensity fires. The understory of Franklin Savanna is mostly buckthorn. Fire is gone. A diverse, intact herbaceous layer and everything it might support are absent.

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This is an oak woodland. Diversity is high. Trees are healthy. Oak regeneration can occur and is occuring. Of course, a big bite was taken out of this one to put in a boat launch.

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Here, another ancient bur oak is overtopped by a young forest of Hill’s oak. For now, the Hill’s oak produce acorns and support insects for abundant wildlife, but this is not a stable system. It’s one wind storm away from being opened up to the possibility of devastation by oak wilt. There is a dense buckthorn understory. The herbaceous layer is largely absent.

If we had a name for the oak savanna that has undergone ecological collapse in a fragmented landscape under immense pressure from numerous invasive species with inadequate human intervention, that’s what we should call this. #@$%-thicket, is one name in use among some people in my field,prompted by the blood, sweat, stick-tights, and bites that often come with moving through such a place. That’s not how I think of places like this. I feel guilt, and there is much to see that makes me dream of better.

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In a true, healthy savanna, this wouldn’t be ugly. Trees die, and in their death provides critical wildlife habitat. Here it is different. These trees are dying and are being replaced by the homogenous landscape of neglect.

What could Franklin savanna be? What should it be? What trajectory might it take to realize its potential to support the most biodiversity in the most need of conservation. How can we make this a place that compels visitors to love the land?

Ancient bur oaks are still there, shedding their masts of acorns onto the dead ground. We can look to other sites that have embarked on similar trajectories towards ecological collapse. A precious few of these have been spared by the simultaneously heavy and delicate hands of visionary people that were able to look at the land and not see just what was lost, but also what could be. These people have executed plans that have yielded spectacular results in a decade or two. These sites, once savannas, are savannas today…probably a little different, but savannas. They are breazy, living, savannas.

Franklin Savanna is now a woods in transition, consisisting largely of legacy oaks and the birds they support, with no regenerative capacity, no structural integrity, and doomed ultimately to become another turn of the wratchet towards a homogeneous, perpetually degraded, forbidding landscape of largely Eurasian plants that capture the energy of the sun, but fail to transmit it through a vital and complex foodweb of native consumers, and instead shed it to decay as litter, some of which even poisons plants and animals alike. Maybe periodic efforts will be made to control invasive species. It’s happened in the past. These efforts are wasted, if the cause of the problem, the complete collapse of community integrity and processes, is not addressed.

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In a few areas, past brush / buckthorn cutting was evident, but many, if not all, went untreated. These areas now have as much buckthorn cover as they’ve ever had, and the work was wasted. Here, one stem (resting at the top of the photo) was cut and replaced by four.

In any case, this place will still be home to plants and animals, some refugees from destruction of closed forests elsewhere. This is a better outcome than an industrial park or a manicured subdivision. Most people, not knowing what was here and having been denied the chance to experience a savanna will see green, and assume all is well. This would be a low bar in the conservation, but it could be greenwashed into a success.

Or we could have a Franklin savanna–the one last large savanna in Milwaukee County. The prescription is clear, though not easy. Franklin savanna, in particular, is the last best opportunity to restore mesic oak savanna in southeastern Wisconsin, and it’s on the right side of the Great Lakes watershed boundary, a magic line that separates abundant from scarce funding opportunities. A steward, volunteer or otherwise and local people that care have a vision and create a plan. Then, they have to cut and treat brush, dramatically thin Hill’s oak, black cherry, and other trees that are common far and wide over the rest of the degraded landscape, seed with as much of the native diversity that can be gathered from the southeastern Wisconsin landscape as possible, develop the capacity to burn frequently, and monitor for and treat new invasive species problems into the future (this will be less an acute problem over time, given the above). If that happened, we might keep our ancient oaks, entice the whip-poor-will and red-headed woodpecker home, and create a refuge of great beauty for ourselves. Others have done it. See the Pleasant Valley Conservancy and the Somme Preserves (with associated blogs). The restoration of the spring flora at the latter, which is crucial for many insects including the now endangered rusty patch bumblebee, is inspiring.

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Over the holidays (Festivus, actually) I visited this savanna in Story County, Iowa, one that was full of Amur honeysuckle in the late 1990s, but which has seen steady and slow improvement over twenty years. It’s a joy when I can take my children to a place that’s healthier than it was when I was young.

It appears this was the expectation when natural area was dedicated. The Wisconsin DNR’s site description says the following:

“Franklin Savanna is an outstanding example of the oak savanna community that once covered most of southern Wisconsin, including portions of western Milwaukee County, previous to European settlement in the 1800’s. Large open grown bur, white, and black oak dominate the site and exhibit the spreading branching pattern indicative of the site’s former open condition. Although the site suffers from woody species invasion due to past fire suppression and grazing impacts, the structural integrity of the savanna is intact and is among the best in the region. Savanna understory remnants are still present in some places and include such characteristic species as big bluestem, little bluestem, shooting-star, May-apple, and yellow star grass. Other species include whorled milkweed, New England aster, hoary frostweed, stiff goldenrod, wood anemone, Pennsylvania sedge, and starry false Solomon’s-seal. The uncommon autumn coralroot orchid also grows here. The southern portion of the savanna is essentially closed canopy due to fire suppression and the subsequent in filling of fire-intolerant species such as big-tooth aspen, basswood, red elm, American elm, and viburnum. With restoration management such as woody species removal, prescribed burning, and interseeding with native understory species, this site may eventually support a broad continuum of savanna plant species and may also be large enough to support avifauna such as red-headed woodpecker, eastern bluebird, and orchard oriole. Franklin Savanna is owned by Milwaukee County and was designated a State Natural Area in 2004.”

The situation today is much more dire than this description.

Maybe we shouldn’t invest the effort, if that effort comes at the cost of something else we assign higher priority. But let’s be honest, we know how to save places like this, but too often we resort to passive neglect, because sites like this cost money and take dedicated, prolonged effort for any effort to be worthwhile. It’s a choice that our children won’t have the freedom to make.

Some addendums based on thoughts from correspondance received in response to this post.

Addendum 1: When is a site like this too far gone? This one might be, or might not be; it depends what we are willing to invest for a positive outcome. There are objectively better opportunities for large savannas 20-40 miles to the west. This site stands for literally hundreds of others in SE Wisconsin, some under public ownership and others under private ownership, all of which are on the knife’s edge of being gone. This site, a State Natural Area where early intentions were for restoration, I think, is a good place to start a reality check. People are too often only given the good news. Perhaps I wonder about the original dedication as an SNA, since it seems to have been based on the hope that restoration work would occur vs. the site actually being even a remotely healthy savanna even then. What do you do fifteen years later when that restoration, a largely unfunded mandate, didn’t happen? Well, it is the only opportunity of this size on deep, fine textured soils in a Great Lakes coastal county, and it is within an important migratory bird stopover site identified in a planning document produced from coastal funding. It’s not as if Great Lakes restoration funding (and it’s a fat purse) couldn’t be delivered here.

Addendum 2: I can’t emphasize enough that these savanna restoration sites aren’t worth the effort, if we are not willing to deploy fire at least every two years. Otherwise, they are neverending money pits of shrub cutting and chemical treatment where volunteers, landowners, and stewards never really get the rewards they deserve. At three years without fire, new seedlings of unwanted woody plants aren’t killed, and over-abundant clonal natives like gray dogwood and sumac actually expand more quickly than they would without fire. Maintenance burning is a cost, not an insurmountable one, especially when organizations pool capacity. It costs far less, for example, to manage prairie (savannas maintenance needs are similar) with fire and monitoring for problems than it does to care for an equivalent area of turf.  What of rare insects? Well, specialists are doomed, if their habitat is lost. Fire is a risk, but it’s possible to burn often enough and lessen those risks by installing protected refugia, dividing a site into 2 or 3 burn units and leaving half or a third of the site unburned each year, and burning different units in different seasons (summer fire may be a key to oak recruitment–MUST READ). When fire is frequent, fuel loads are low, and many sites will have patches that go unburned. Lastly, a large, healthy savanna should probably have some thickets of native shrubs/small trees like hazelnut, wild plum, prairie crabapple, nannyberry, juneberry etc. These thickets don’t burn, at least not during prescribed burns conducted under the less volatile conditions covered by local permits. These are also refugia for some insects and other wildlife. These thickets, however, are an element of the savanna that will always require continual buckthorn removal (gardening) in today’s world…or at least for now, because that is such a specific element that only a few people are thinking about in the context of savanna restoration.

Addendum 3: What should Milwaukee County do? I don’t know, and it isn’t for me to say. My reaction to the reality on the ground is visceral, but it’s not because of bad people. To restore this site would require a different model of conservation. It would take volunteer steward that is very involved, knowledgeable about savannas, that collaborates extensively with those involved in savanna and prairie restoration, and that can leverage community support (a corps of volunteers, support for burning, etc.). Does anyone like this live nearby enough to have the necessary presence? Maybe. Maybe not. It’s also true that the County has a lot more closed mesic and dry-mesic forest in its portfolio, which have fewer needs. It’s not unreasonable to focus on those forests, which also see more vistiors (e.g. Falk Park). …but where does this leave this site?

Addendum 4: I used to wish I could have seen the landscape in 1800. Now I’d settle for 1960. I wonder if either children of mine will feel the same way about 2000. At this point, it’s not what we’ve inherited, but what we’re carrying forward for those who will replace us.

 

About prairiebotanist

www.prairiebotanist.com
This entry was posted in biodiversity, Conservation, Forests, invasive species, native plants, Oak opening, oaks, Prairie, restoration, Savanna, Stewardship and tagged , , , , , , . Bookmark the permalink.

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