This post is intended for people who are interested in the details of ecological restoration. It consists of five “cases” – with photos that exhibit problems or opportunities accompanied by comments on possible solutions.
First, a definition of a word used often below:
conservative – a species that is most common under natural conditions – and rarely is found away from them. In ancient prairies, the conservatives are among the most common plants. In most “restored” or degraded prairies, they are rare or non-existent. There’s a longer note on conservative plants at the end of this post.
Diagnosis: Weeds under control. Yet few conservative species are established. Most of what we’re seeing here are short termers – species that will give way to others, for better or ill, before long. The early goldenrod, for example will likely be replaced excessively by big bluestem (present now in small numbers) if nothing is done but burn.
Prescription: Broadcast seed of conservative species. Especially important are little bluestem and prairie dropseed – to head off the big bluestem. Sow seed of most difficult to establish species in the early goldenrod areas for best results.
Case 1A: close-up area 1
Patches like this strike me as the very most receptive to our most prized conservative seed. There is currently little aggressive tall grass here. The commonest plants shown (early goldenrod, black-eyed Susan, fleabane) are among the quickest to move out of the way for quality species. Sow such classy species as cream false indigo, Leiberg’s panic grass, white and purple prairie clovers, prairie dropseed, alumroot, shooting star, prairie gentian, yellow stargrass, prairie cinquefoil, etc.
Case 1B: close-up area 2
This patch shows quite a bit of young big bluestem along with many young ash trees and dogwood shrubs. A patch like this may be somewhat less prime for new seed. Given how little seed we have of the high conservatives, we should seed this area sparingly. Perhaps it’s a place to add somewhat aggressive species like rattlesnake master, prairie dock, compass plant – to increase the diversity of niches that the high conservatives will use to gradually become established from nearby over the decades.
Here two high conservatives dominate (purple prairie clover and prairie dropseed). Early goldenrod (which was dominant here years ago) has retreated to the frequency you might expect in stable, high-quality grassland. Although we see a little rattlesnake master, compass plant and rough blazing star, theoverall diversity seems low. It might not work so well to sow the high conservatives of mid-summer; the competition could be tough to overcome. Perhaps this is a place to sow spring species such as prairie betony, shooting star, and cream false indigo, which might then open up more niches.
On the other hand, this area is currently a great seed source for dropseed and prairie clover, so perhaps there’s no need to do much here in the short term. The best next step could be a variety of little inter-seeding experiments. First, find out which species will compete against these conservatives – before investing a lot of seed in an area, which might be slow to accept it.
Two big questions here:
A. This is a new planting with good wildflower diversity but weak on grass (and thus, unstable). It’s hard to know whether it wants to be more mesic or wet-mesic overall. I’m thinking that we should focus on sowing dropseed and little bluestem in the drier parts – and switch grass and Dudley’s rush in the wetter parts.
B. But the biggest question here is what to do with all those trash trees in the background. Both parts of this area were so dense with buckthorn that essentially no grasses or wildflowers survived. But the foreground area had few big trees, and we managed to clear them. In the background, large numbers of ash, cherry, elm, and box elder trees hold sway. It would take a big chunk of our volunteer time to cut and burn them. But there’s no sensible community to try and restore on the former prairie land underneath them. So our short-term strategy has been to plant natural species that may keep out the invasives and then wait until we have a better answer. If you look closely you may be able to see brown leaves on some of the trees to the right. That’s where fire singed some of the branches. Maybe fire will do most of our work for us here, while we invest our resources on other areas where the prescriptions are clearer.
In this patch of scarlet oak savanna, we seemed to be getting increasing diversity and quality – until recently.
Around the tree on the right, notice wild quinine, butterfly weed, ox-eye sunflower, big bluestem, wild bergamot, rattlesnake master, and others.
Then woodland sunflower (Helianthus strumosus) started wiping much of it out. Perhaps this is a temporary stage, and diversity will come back? Or perhaps this sunflower is helpfully erasing species that aren’t so well adapted here, which would then be replaced by better-adapted species, if we broadcast their seed. We should experiment by inter-seeding such species, if we can identify good candidates.
Diagnosis: About half the trees in the center grove are dead. Some died from fire and others from Dutch elm or Emerald ash borer disease. The few oaks are fine. (In contrast, the grove on the left is mostly oaks and doing great.) Because we hadn’t had time to focus on it, we’ve left the dying grove to “nature.” Of course, “nature” isn’t happening here, and the result is an increasingly unsustainable weedy and brushy mess. It will soon be another buckthorn monstrosity if we let current processes continue.
We could plant two of our precious mixes of rare grasses and wildflowers of the species (first the one of species that would survive in the semi-shade of the edge – and second, further in, the mix of species for the shade of the grove interior). That could help keep the buckthorn at bay, but it could also be a waste of seed and effort, since the species that would grow there in the short term would not be adapted to the less shady conditions that are coming – as these mostly non-oak trees continue to die.
Perhaps we could broadcast the seed of some of the easier to get semi-shade herb species in the hopes that they will seal the wound and ward off the brush. Or we could plant natural shrub-copse species in hopes of another native shrub island that we could experiment with (much appreciated by the significant bird species that nest at Somme).
Or we could short-circuit the misery and cut the out-of-place trees this winter. That would seem easiest. We could then just plant the open savanna/prairie mix (as in the foreground here), which would then be easily sustainable with little added effort beyond regular burns. But we’re trying to restore the natural savanna here, and we already have more than enough of the “prairie” component.
I’m inclined to recommend planting hazelnuts and bur oak acorns and protecting them from voles, rabbits, deer and fire in the early years. Perhaps some of the box elders and basswoods can for the next 15 or 20 years provide the amount of shade that oak and hazel will someday provide, and the community can transition gradually from non-oak to oak. This challenging area still needs a lot of observation, experimentation, and thought.
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... and, as promised at the end ...
a longer note on ecological conservatives
In many ways, the main and most challenging goal of ecosystem restoration is to establish plentiful conservatives. If such plants and animals are diverse and common, all the others will be intermixed with them, and we will have achieved the fundamental goal of conservation.
The quality of conservativeness is in the early stages of study, but good initial assessments for all plant species are available in the Floristic Quality Assessments that are now available for most Midwestern states and a few other regions.
Conservativeness is ranked on a scale of 0 to 10, with 10 being the highest. Examples of plants in the 0 range include ragweed, annual fleabane, and common milkweed. Typical alien weeds like dandelion would also be given a zero rating if these ratings weren’t reserved for native species.
Examples in the 9 and 10 range include prairie dropseed, white prairie clover, fringed gentian, prairie gentian, cream false indigo, prairie lily, Leiberg’s panic grass, prairie cinquefoil, prairie sundrops, heart-leaved Alexanders, and the prairie white-fringed orchid.
Conservative animals may or may not require conservative plants. But the ecosystem is less without them. Examples of conservative butterflies found by Ron Panzer to require conservative vegetation include the regal fritillary, Aphrodite, and the Edwards hairstreak. Birds of conservation concern may live for a time in some large pastures of alien grasses. But they’ll live sustainably in large high-quality prairies.