Burning Butterfly Questions

Burning prairies is good for native prairie plants and bad for butterflies. That’s what just about all of the guidance for rare butterflies says. It’s the conventional wisdom. Those that question it are reluctant to do so. Allow me. I like butterflies too.

Let me build from an anecdote. In the summer of 2003, I had my first experiences on prairies with regal fritillary butterflies as an intern doing botanical inventory, seed collecting, and management in west-central Iowa. These were were postage stamp, remnant prairies, generally a few to 15 acres in size, and utilized for seed / genetic resources. They were burned frequently by their manager, and a few of them still had large regal fritillary populations. These are large, active, beautiful butterflies. To share a meadow with them is a life experience. 1024px-Speyeria_idalia1

If people knew the beauty of the regal fritillary, they would care about it as they do monarchs. I’m ashamed to say that I never actually photographed one, so I’m reduced to finding an image in the public domain.

So I went about my summer bagging the unripe capsules of prairie phlox to catch the seeds upon explosion and painstakingly gathering not-insignificant amounts of seeds from prairie blue-eyed grass and Leonard’s skullcap, but when I staightened my back, I watched the regals gliding over the prairie.

These prairies were loaded fritillary host plants–prairie violet, bird’s foot violet, or both. There was also no shortage of nectar for butterflies in flight.

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This dry, sandy prairie had a very robust regal fritillary population. It was burned almost annually. The regals were there in 2003, and still again when I used the sites for my dissertation research in 2009. The floral display is scaly blazingstar (Liatris squarrosa).

Researchers from Iowa State had been on one of the prairies to study the regals. Among other things, research in Iowa has shown that the regals don’t leave the prairie. They fly over the prairie, but if they come to a row-crop field, they turn around. They don’t cross tree lines either.

These prairies were healthy, and they were getting healther. One site, which seemed mediocre when I visited it in 2003, because it was more tham half smooth brome, had become probably the best mesic prairie I’ve seen to this day with frequent, if not annual, spring fires.

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This mesic prairie was basically about half brome in 2003. Smooth brome was not even detectable in quadrat sampling in 2009.

In 2009, after several more years of annual burns, the prairies were still there, and so were the regals. The prairies were better than ever, the regals certainly no worse.

This brings me to the science. Much of the older science, which still informs management recommendations for accomodating regal fritillaries today, was speculative. Fire has to kill larvae. Right? They don’t reside underground. There must have been some extremely efficient dispersal and meta-population stuff going on when much of the regals’ range burned frequently before Europeans began their misadventures in stewardship. Or not. At Konza Prairie, in the Flint Hills of Kansas, where I was based in graduate school, and where I also had the privelege of sharing prairies with regals (and slender glass lizards, collared lizards, ornate box turtles, bison, and prairie chickens), host plants were common. Regals were common. Many areas with regals were burned frequently.

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This is what it looks like when “the Konza” burns. I was party to dozens of these. There are fritillaries, collared lizards, and box turtles here. They survive and thrive somehow.

Most lepidopterists would be aghast. It’s a moonscape, black and barren.

Well, over the last decade, people have started looking what is going on more close, starting at Konza and the Fort Riley Military Reservation. There, a research team concludes:

“Our results indicate that greater host plant density and short fire return intervals are important to the occurrence of late-instar larvae and despite current management recommendations, larvae may be negatively impacted by a lack of fire. Preliminary analysis of adult data suggests that adult density was greater in areas that were grazed and had a 3-5 year fire return interval. The conservation management implications of these results to the persistence of regal fritillary populations within the region may require a re-thinking of previous assumptions.”

Looking deeper into their research, published in the Journal of Lepidopterists, it seems like larvae are present even following fires in burned areas. How? Larvae were obsered to burrow down or hide under rocks, which is sufficient to survive a quick-moving prairie fire, and apparently they survive until their host plants resume growth (which is pretty immediately). An interesting aside–regals are also utilizing other common violets (Viola sororia) on Konza. That raises other questions, which I’ll leave. I am not at all surprised by the fire response though. Regals are a prairie species. A few might die, but their host plants and nectar sources are more important in determining how well they do than any stress fire puts on them, and not having fire really diminishes their host plants, which get burried in grass litter and die.

Here in Wisconsin, regals are endangered, and Wisconsin Department of Natural Resources guidance suggests that things might be different:

“Grassland management activities must be adjusted where regals are established in order to maintain the populations. Sites that experience frequent controlled burns (less than 5-7 year rotation) exhibit reduced numbers of butterflies therefore burn management should be avoided on regal sites.”

We have newer information for Wisconsin, which frankly makes a lot more sense. Henderson, Meunier, and Holoubek published research in Biological conservation that reaches this conclusion:

“Burning every 3-5 years maximized regal fritillary abundance, but even annual burning was more beneficial to regal populations than no burning at all. Unburned refugia are important in maintaining populations, but creating and maintaining high quality habitat with abundant violets (Viola spp) and varied nectar sources, may be the most impactful management and conservation tool. Regal fritillary butterflies were consistently more than twice as abundant on high quality habitats and this relationship held across, and often dwarfed the effects of, various prescribed fire regimes or climate variability.”

So when we are considering this species, which we should care about (though it is extirpated within my professional realm), considerations for maintaining the habitat are most important.

Now we arrive at philosophy. Our natural resource base has been so degraded, that reductionism, which is the consideration of particular species that are still hanging on for some reason or another, is growing. The guidance still in force is reductionist. It’s about butterflies and potential direct impacts to them. It ignores ecology, that the butterflies are inextricably tied to a system, and particularly to the success of their host plants and nectar resources (though these also have intrinsic value). We cannot manage for regals without considering the system as a whole. We also cannot manage for regals without considering evolution and the arc of time. Regals, their host plants, and their nectar plants existed long before we were here, indeed they existed even when much of their range in thee Midwest was under ice. Their connections are deep and long-standing, but insofar as the old worlds they occupied seem alien, it offers hope for the future…and apparently more host plant flexibility than we knew (which might explain the extirpated Cedarburg Bog population). Maybe we can slowly bring back the summer flights of the regals and add more romance to peoples’ lives, if we also consider the other key elements (fire, violets, and nectar, all things we get from well-managed prairies), and think beyond the species.

As an addendum, I can’t help but think of the Powashiek Skipperling, a much less charismatic, but no less important, lepidopteran that is federally endangered. Several miles to my south, years of burning and brush cutting brought back some prairies from the brink, and the poweshieks, which apparently had persisted in low numbers came back. Then came concern. Burning in the core areas stopped. Powashiek’s primary host is prairie dropseed, a very conservative grass with high affinity to high quality, undisturbed prairies. Prairie dropseed thrives with fire. Without it, it burries itself in it’s own litter; it survives, but in a much less productive state. Also, many of the potential nectar species while Poweshiek’s are in flight flower much more abundantly in years after fires.

The last flight of the Poweshiek Skipperling in that place, despite survey efforts, was four or five years ago now. Poweshieks are grassland butterflies. I can’t help but suspect that the best intentions squandered that opportunity. There is some, but not much, research that addresses Poweshiek’s response to fire. I have to say it’s dubious in terms of inference, given the type of data collected. The greatest deficit, I think, has been a failure to consider the resources that species depends on and what actually happens to larvae, and how many, when their prairies are burned.

 

 

Posted in biodiversity, Conservation, Conservation own-goals, Prairie, restoration, Stewardship | 3 Comments

Rough Thoughts on Restoration and Diversity from the Arid Grass and Sage

I was looking back. This is still me, but maybe I need to dig deeper to find it.

Prairie Botanist

or1.jpg Sage on my left and crested wheatgrass on my right on my way into the deep nowhere of high desert Oregon.

We live in a society that replaces craftsmanship and beauty with functionality. We don’t raise animals. We produce them by the tens of thousands inside walls, and then we thaw and heat them according to the instructions on the package. We don’t build cathedrals. We put churches in strip malls. Most red barns are sided with sheet metal. Most new houses are sided with vinyl. I think this cheapness has metastasized into our view of the natural world and ecological restoration as a practice. We should raise our standards, and consider beauty and complexity and what they add to human experience.

Restoration seeks to recover aspects of a natural system that have been lost through some form of disturbance, usually resulting from human activities. Ask a scientist to provide…

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Alternatives to Boring Midwestern Bluegrass and Fescue Lawns

For most of us, home ownership carries with it the management of at least a small parcel of land, and usually this means maintaining a lawn. For the ambitious, this might also include perennial borders, shrubs, and trees. We all need outdoor space to recreate in. Our neighbors all have lawns. People seem to like them. Right?

I killed our bluegrass and fescue lawn. I have methodically replaced it over the last five springs, summers, and falls with species native to North America. Why? I’m an ecologist, and I see irreplaceable natural communities and ecosystems being degraded and destroyed every day and almost everywhere I go. Oftentimes, these types of environmental problems are large and intractable, and working against them is like screaming into the wind. One thing I can do is live my values at home. I also just like to be around plants and all of the organisms they attract. More than 500 North American plants are established on our half-acre lot.

I’ve also found that it’s just a very doable and practical course to take. Sure, it takes work to kill a lawn, prepare a site, and establish a native alternative. However, now that I am largely finished, I spend an hour or two on weekly maintenance during the growing season, which is less than my neighbors spend on their bluegrass and fescue lawns.

I also believe that the grass, border, and bed paradigm of landscaping is destructive. It strives to keep us in on the turf and away from nature and wonder. I don’t want to live that way. Do you?

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Typical lawn with a border and a bed of perennials and shrubs arranged as ornaments in a decorative mulch of gravel. How lame!

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A view of part of the back yard. This includes a more intensively used turf area near the house, which consists of North American species like buffalograss, side-oats grama, poverty oat grass, several sedges, and several low-growing wildflowers. Working out from this, native vegetation is less intensively managed and taller. There is no border or edging. The point of this configuration is to draw people in among the surrounding native vegetation.

Also, using native alternatives in turf areas opens the door to adding a lot of diversity. There are more than forty North American species in my turf (the short, occasionally mowed area–not the surrounding taller stuff), which host specialist foliage feeding insects (e.g. moths and butterflies), provide pollinator resources, and provide my human mind with interest throughout the season.

Existing turf and Eurasian weeds can be killed by a number of means. They can be smothered with an opaque covering like cardboard over the course of several months. They can be dug out. They can be treated with a non-selective herbicide. I have utilized all of these means, but to the likely dismay of many, I prefer the latter. It is effective, practicable, minimizes soil disturbance and the potential for erosion, and it allows one to get native plants into the ground so they can do what they do almost immediately. There are potential risks in the occupational mixing and application of things like glyphosate, but judicious use that paves the way moving forward for a landscape with no need for herbicide, pesticide, and fertilizer is worth it. The soil is not poisoned, nor is the water. Once the turf is dead, any flushes of annual weeds can be easily removed with a flame weeder.

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In the background is an area that was treated with glyphosate and has already been planted. In the foreground is an area where turf was dug out in my haste and desire to do work early in the spring before the lawn greened up and could be treated; this was more vulnerable to erosion until plants filled in.

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This is the torch I use. It hooks up to a standard propane tank. It’s clunky, but it’s fun to use.

What you replace your exotic turfgrasses with depends on how you use your space. We only intensively use a small area of the back yard, so that is the only place where we maintain a lawn consisting of North American native species. Elsewhere, we have landscaped with native grasses, sedges, wildflowers, shrubs, and trees. Regardless of use, I have found one particular mode of establishment to be the most effective–using transplants. This way it is easy to weed. Seeding, while feasible in some instances, creates situations where weeding is more difficult, and weeding is essential for outcomes that are aesthetically pleasing and low maintenance. I do use seed from time to time, especially in cases of species for which transplants are not available, fresh seed germinates best, or that I establish among transplants after I feel reasonably certain that weed problems have been overcome.

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Divisions transplanted into an area where the turf was recently eliminated

More specifically, a low maintenance and a pleasing look can be achieved by the imitation of natural native plant communities, which often means creating a “matrix” or “living mulch” of bunch-grasses or sedges (and perhaps a few specific forbs for specialized situations) often by spacing transplants 12″-18″ apart and interspersing wildflowers of appropriate height between and among them. These then fill in within a few to several months, and once that happens, if you’ve weeded in the interim, you will have to do very little weeding in the future.

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This remnant oak woodland and its rich groundlayer vegetation are among my inspirations.

Following are tons of examples of this from our home landscape with brief descriptions. I really have no conclusion here beyond offering these images and trusting that they, despite my lack of photography skill, are compelling.

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Here, Pennsylvania sedge (foreground) and Sprengel’s sedge (background) were established from transplants with spring beauty and forked aster. Things filled in within one growing season, and this is a very pleasant area to stroll through.

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This is a different view of the same area in the previous picture. Other sedges than those already mentioned include James’ sedge and hairy wood sedge. Mulch is reserved for a meandering footpath, but the surroundings don’t prevent one from leaving that path.

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As the season progresses, great blue lobelia, hoary skullcap, forked, aster, purple Joe Pye weed, and others become more prominent over the sedges.
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This area along the sidewalk leading to the front door isn’t filled in with grasses and sedges, but native groundcovers including Robin’s plantain (which takes foot traffic), prairie smoke (which takes foot traffic when not in flower), and northern bedstraw. The lighter green groundcover around the birch tree is grove sandwort. The open shrubs in the upper left are false indigobush, which let’s through a lot of light and allows for underplanting. The shrubs in the upper right are low bush honeysuckle (Diervilla lonicera…not the invasive bush honeysuckles).

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This is more or less the same area pictured immediately above, but a little later in the spring. Mountain blue-eyed grass and Robin’s plantain are in full bloom. Prairie smoke’s wispy seed heads are visible, kinnickinnic grows in the foreground. These plants are chosen to be showy, low, and unimposing near the front entryway to the house.

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This is an area of high-use lawn in the back yard. The foreground falls mostly under the shade of a mature bur oak and was planted with wood sedge transplants and poverty oatgrass seeds (one for which seed is more practical for establishment). This transitions to buffalograss in the background where there is at least half a day of full sun.

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This turf of buffalograss with small amounts of hairy grama, blue grama, and side-oats grama mixed in is growing in sunny portions of the high-use area of our back yard. It stands up to regular traffic, and as of now in our sandy loam soils, it has held up to Wisconsin weather through four growing seasons and winters.

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This was among my first plantings at this address. Here, prairie dropseed and little bluestem form a matrix into which butterfly milkweed, pale purple coneflower, and many other wildflowers have been planted. Towards the bottom is a somewhat more moist swale where sedges have been used to fill space and inter-planted with foxglove beardtongue, compass plant, marsh milkweed, and others. The shrub in the lower left is buttonbush. The lawn on the other side of the driveway is now all gone.

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Early buttercup and common blue violet blooming around the margins of the high use area in the back yard. Early buttercup is among the first flowers to bloom for me, often beginning during the first week of April. Both violets and early buttercup establish best from fresh seed. These are mixed here with grasses like poverty oatgrass and sedges, which are more prominent as the season progresses.

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This area was planted with transplants during the previous fall and had not quite filled in as of the time of this photograph. Robin’s plantain and round-leaved ragwort (another that tolerates foot traffic) are the groundcovers that are in flower. Nodding onion and Jacob’s ladder are visible, but not in flower.

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Kittentails (tolerate foot traffic), poverty oat grass, buffalograss, and common wood sedge co-mingling near the edge of the oak canopy

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Foliage of cat’s foot, prairie ragwort, winecups, parasol sedge, prairie violet, and hairy panic grass in area occasionally walked on between a foot path and the compost bin.

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An August scene of buffalograss lawn with royal catchfly, little bluestem, butterfly milkweed, and Maryland senna in the background

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More buffalograss, with a rogue white clover that I hope I didn’t miss

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Cardinal flower and forked aster make a good combination in late summer along a mulched path. Purple Joe-pye weed and starry campion flower under the oaks in the background.

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Prairie blazingstar, marsh milkweed, and slender mountain mint in the moist swale down by the road

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Showy milkweed with fox sedge, prairie dock, and Kalm’s St. John’s wort in the moist swale down by the road

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Ohio horsemint and Ohio spiderwort make for a purple early summer show on the front slope. The line of shrubs in the background consists mostly ninebark of and fragrant sumac.

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Royal catchfly, grove sandwort, cat’s foot, and some Pennsylvania sedge under a birch tree and false indigobush.

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Round-leaved ragwort, Robin’s plantain, and wild geranium

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Woodland phox, Jacob’s ladder, bishop’s cap, amethyst shooting star, pedunculate sedge, swamp saxifrage, leatherwood, large yellow lady’s slipper orchid, little yellow lady’s slipper orchid, and some violets between the front sidewalk and the house (faces north-northwest). There was an overgrown yew hedge here when we moved in.

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High spring in the side yard. There is a lot of wild geranium, common wood sedge, round-leaved ragwort, wild strawberry, and White Bear Lake sedge in this picture.

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Woodland in the foreground transitioning to little bluestem and prairie dropseed on the slope down to the street

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These wood betony seedlings are from seed given to me by Chris Mann. Wood betony is semi-parasitic and best sown into bare spots among established sedges or grasses.

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Grove sandwort is a great groundcover for dry, bright shade like that found under birch, aspen, or oak. It doesn’t take as much foot traffic as plants arising from rosettes, however.

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Obligatory monarch on milkweed

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Showcasing parasol sedge growing with buffalograss

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Showcasing plantain-leaved sedge in full flower

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Showcasing pedunculate sedge in flower

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The year ends on a grassy note on the front slope. All seasons are different, and that is greatly appreciated by me as I pull over for the mail when I arrive home from work.

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Meadow blazingstar with prairie dropseed, side-oats grama, and prairie blazingstar

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Ohio horsemint with butterfly milkweed, large-flowered beardtongue, prairie dropseed, and little bluestem

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Purple milkweed with butterfly milkweed

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Cat’s foot, a reliable host for American lady butterflies in an area that gets walked on a lot

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Asters, goldenrods, and royal catchfly with little bluestem and side-oats grama late in the summer

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Prairie and meadow blazingstar, little bluestem, prairie dropseed, whild quinine, slender mountain mint, marsh milkweed and American burnett in the swale by the road. This area is swarmed by monarchs when the marsh blazingstar comes into full bloom.

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Young planting with wild lupine, prairie dropseed, and large-flowered beardtongue

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Smooth rose, Canada anemone, and bracted spiderwort are kept in check by other aggressive plants in the swale and are unable to aggressively spread uphill, because it is too dry and sandy on the slope.

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Large-flowered beardtongue

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Here are more asters (especially Short’s, Drummond’s, arrow-leaved, smooth blue, and New England) and goldenrods (especially elm-leaved, zig-zag, and showy) under oak along the property line. What you can’t appreciate from the picture is the sound of bumble bees and other native bees, which is audible from about ten feet away.

 

Posted in alternative lawns, biodiversity, gardening, native plants, Prairie | Tagged , , , , , | 3 Comments