Diversity - Close, Middle, and Distance

Comments on three layers of a photo:

Foreground

This photo shows restored prairie (foreground), restored savanna (middle layer), and an artificial woodland. But there's a lot more than that.

Up front, scarlet painted-cup blooms. This rare plant (Castelleja coccinnia) seems to be a refugee, mostly gone from the Chicago region. We protect our few plants from deer and broadcast its seeds widely around the preserve, hoping it will find places where it will sustain itself without further help. It only appears in most spots sporadically, but in some small spots in good numbers, year after year. Mostly it thrives among other rare plants. Here it's among restored purple prairie clover, lead plant, wild quinine, bastard toadflax, rattlesnake master, Leiberg's panic grass, and more diverse prairie grasses and forbs. But there are many other acres of similar restored richness that scarlet painted-cup does not seem to like. In still other spots it grows with different lists of rare species, in both wetter and drier areas. 

None of the more conservative plants shown above were at this spot when we started the restoration, in 1980. Year after year. rarity and conservatism increase. Many formerly common, less conservative plants disappear or are diminishing.  

Near Distance

A few feet back starts an area of burned-back but resprouting hazel shrubs and oaks. They're part of the structural diversity of savanna. Two hundred years ago, according to the earliest survey, this spot stood at or near the transition between prairie to the west (left) and savanna to the east. In the photo, the closest charred sticks are hazel-nut bushes that were top-killed by fire last spring. Behind them are burned small trunks of Hill's and bur oaks. As was once standard in parts of the savanna, re-sprouting oaks and hazels became "grubs" with huge root systems that farmers found difficult to "grub" out, thus their name. 

Some rare species seem to be associated with the cyclicly brighter and shadier areas around Somme's increasingly impressive grubs, as they grow and expand for a few years and then are burned back. We wonder about the formerly-Illinois-Threatened species, small sundrops (Oenothera perennis). The few plants we first found in this area increased to 303 in the 2010 census but gradually lost out to more conservative plants in the completely open areas. They then decreased so that none were found in 2017, six were found in 2020, and seven in 2022, mostly near invasive trees that haven't yet been removed. We occasionally find them near burned grubs. Will this "resprout shrubland" be a permanent home for them? 

Way In Back

The grove of trees in the distance was planted by Forest Preserve staff decades ago, before biodiversity was even a word.  On the left, above, you can see through their trunks to original prairie areas, beyond. Buckthorn and most other invading and planted species have been cut and burned out of that grove. The remaining trees, mostly white oaks, are gradually being thinned to restore savanna, the natural ecosystem and conservation priority here. In the meantime, plentiful oak leaves assure that such an area will largely keep free of invasives, as they burn well when the surrounding prairie and savanna are burned. The future of these areas depends on hard work and strategic decisions. 

What is unfolding here is thrilling to watch, if you can see it. One of the best ways to learn is to participate. But you still have get to know the plants and animals to experience this slow drama deeply. One person who expressed it well was Greg Spyreas of the Illinois Natural History Survey in a publication called Natural Areas of Cook County: Somme Prairie Grove and Somme Prairie Nature Preserves: 

“Somme Prairie and Somme Prairie Grove Nature Preserves comprise one of the finest tallgrass prairie, wetland and savanna complexes in Illinois ... Along with the 250-acre Somme Woods Forest to the east, the slow return to health with prescribed fire, seeding reintroductions, and invasive exotic species removal in this preserve has been breathtaking to behold.”  

Endnote

The Illinois Natural History survey publication quoted above is one of a series of brochures celebrating the natural areas of Cook County. Credit on the back of the publication goes to Illinois Natural History Survey, Prairie Research Institute, Forest Preserve District of Cook County, University of Illinois, and Boeing (apparently because this corporation generously funded the publication). This fine series is a credit to all involved.   

Acknowledgements

Thanks, as so often, to Eriko Kojima for proofing and edits.