Monday, July 29, 2013

Planning Notes for 2014


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.




Case 1

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.
  

Case 2

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, the
overall 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.

Case 3
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.

Case 4 
            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.
           
Case 5 
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.
Prescription
            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. 

5 comments:

Anonymous said...

Stephen, This is another great blog post. First off I think Pedicularis canadensis would be a great plant to seed into areas where competitive grasses are beginning to get established or have begun to out compete forbs. The volunteers at Nachusa have mentioned their successes frequently with P. canadensis. In areas where Cornus racemosa is present I would suggest sowing seeds of plants that do equally well in sun or shade. Plants that survive the transition from open conditions to a canopy of Cornus racemosa and back include at least Maianthemum stellatum and one of the Triosteums. I’m sure there are more, but I cannot remember them at the moment. If I were to give you one criticism, it would be that you need to mention the spring growing graminoides, like many sedges, when you speak of your mixes. Finally, for the island surrounded by dead trees I would plant species that are found just as frequently in prairies as in open woodlands like Elymus canadensis and Zizia aurea. However, the best course for the island of trees really depends on what you envision for the area.
Sincerely,
James

Daniel said...

Stephen,

A truly educational and thought-provoking post. Some thoughts:

Case 1B: Is it safe to say that areas of non-conservative grasses (big bluestem, switchgrass, cord grass, etc.), young weedy trees, and shrubs are not good candidates for seed because of the shade that they cast? Or is the fact that many prairie grasses have massive underground networks of roots that can soak up water and nutrients too much for a tiny seed hoping to germinate?

Case 2: From a restoration standpoint, is it better to strive for a stable, conservative community or a dynamic, mixed one? I imagine that a dynamic, mixed community would always hold more potential to be attacked by invasives, but it seems as though you suggest that creating niches for conservatives is the most important goal for ecosystem restoration.

Case 3: Why do grasses signal stability in a plant community?

Why is there no "sensible community" to try to restore under the trash trees? Aren't there other areas of Somme that started out at deserts under a buckthorn canopy? Isn't there a possibility there is a native seed bank lying there in the soil?

Case 4: The woodland sunflower invasion you're experiencing highlights, in my opinion, the hardest part of being a steward. We all know that the ecosystem needs our help to thrive. When does a steward decide that an invasion from a native plant crosses the line from a "natural occurrence" to a "serious threat" and when does that warrant human intervention? Similar to the parasitic Dodder you have at Somme, when does a steward decide that a plant is or is not providing a natural/needed disturbance?

I know most of these questions do not have a single answer. The challenge is to adapt to whatever site you are working on and make decisions that will work best there. Thanks again for a fascinating look at what goes through a steward's mind on a daily basis. It makes what you all do even more admirable.

Stephen Packard said...

Daniel, thanks for the perceptive and helpful questions. I'll respond, but first I should mention that your good detail reminds me of the limitations of this medium. Who'll have the time to read deep into so many questions? There must be better ways.
As to1B, I don't know the mechanism(s), but I do know that the tiny seeds of prairie betony and shooting star will establish well in dense big bluestem, but the bigger seeds of prairie dropseed seem not to do so. My experience suggests to me that many of the twenty or so conservatives I'll plant will do better (establish in larger numbers) in the more complex turf of smaller species. Perhaps dense shade in summer is the bigger problem (which is avoided by spring ephemerals). Big grasses, shrubs and trees may kill seedlings that need to get sun all summer long. On the other hand, I've had good luck seeding prairie clover into dense big bluestem. Lots of study and experiment are needed here. Possibly many people have done it but haven't shared their results.
Case 2: I believe that a community with plentiful conservatives is both stable (in that it somewhat resists brush and invasive species) as well as dynamic (with many species constantly replacing each other).
Case 3. One reason why grasses promote stability is that they assure good fires. Diverse grasses provide diverse niches for the establishment of diverse species.
There's little native seedbank in most prairie and woodland situation (but there is in wetlands).
There's probably no "sensible" community under box elder etc. because without prairie grasses or oak leaves it probably won't burn easily. The only likely fires would be extreme fires under extreme conditions, after which the ecosystems would start over. Somme doesn't have the species for that dynamic.
Case 4. The problem with woodland sunflower is that it seems to kill off most of the competition. Perhaps that's part of a natural process that gets to diversity. But perhaps it becomes a destructive imbalance that harms diversity in the "intensive care" condition that Somme is in. Perhaps, for example, we should try scything woodland sunflower in some areas a few times and see if it then become a part of a diverse community. Or perhaps my current thinking on this is too short-sighted. Many experiments are worth while.
Daniel, thanks again for the good thoughts.

Pat said...

Thanks for this. Wonderful. I offer this comment about aggressive native growers and let nature take its course in managing them over the decades. It would seem that little attention is given to the fact that we've lost a great majority of our natural disturbances that would help to keep these guys in check. Great herds of large animals trampling, grazing, fighting, mating, or just plopping down to rest, or die. Large volumes of smaller clawed animals prone to scratch and burrow. The natural order of disturbance is greatly out of order so it would seem people have to step in to put aggressive natives in check.

Anonymous said...

Stephen, The following blog post by Chris Helzer is insightful regarding mechanisms for seedling establishment where there exists competition with a dominant grass. Like you, Mr. Helzer is also studying the ability of species to establish from seed after reducing the competitiveness of a dominating species.

http://prairieecologist.com/2011/03/15/using-defoliation-of-dominant-grasses-to-increase-prairie-plant-diversity/

Sincerely,
James