Japanese Stiltgrass (Microstegium vimineum) is a much-maligned “invasive plant,” but I don’t believe it deserves this reputation. Call me crazy, but personally, I love stiltgrass. And why not? She is beautiful, like a tiny bamboo forest. She clothes herself in a luxurious green and beams with lushness every morning dew. And she is also helpful… but I’ll get to that later.

Originally from east Asia, stiltgrass was introduced accidentally to Tennessee around 1919, after having stowed away from China in some packaging materials. Stiltgrass is an annual, seeding profusely, and able to remain in the seed bank for several years. Unusual for most grasses, stiltgrass grows in low-light conditions.

It has been claimed that stiltgrass invades healthy, biologically diverse, native plant communities. My own observations do not bear this out. What I see is that stiltgrass is especially abundant in recovering first-growth forests – places bearing a history of anthropogenic degradations and exploitations. Young woodlands with stiltgrass understories, like the ones I see around the southeastern USA and mid-Atlantic states, may be characterized by pioneering species like tulip poplar (Liriodendron tulipifera), black cherry (Prunus serotina), black locust (Robinia pseudoacacia), red maple (Acer rubrum), and box elder (Acer negundo).

Tulip poplar, red maple, and box elder all have something in common: wind-born seeds. And black cherry is planted through bird droppings. Black locust can be dispersed by wind as well as by birds. Other species I commonly see among the stiltgrass community are shrubs such as bush honeysuckle (Lonicera maackii), vine honeysuckle (Lonicera japonica), autumn olive (Elaeagnus umbellata), barberry (Berberis thunbergii), and multiflora rose (Rosa multiflora), all of which are also planted by birds. These dispersal vectors are important considerations, and they suggest a meaning.

Important questions to ponder are how and why such a particular assemblage of species comes to be in a place. One thing to consider: in such areas, there is no longer a native seed bank! If the native seed bank is gone, it is almost always for one reason, and one reason alone – agriculture. Looking back in time, perhaps the place was once an agricultural field where many years of plowing and tilling destroyed the seed bank. Or maybe it was once pasture land, and many years of over-grazing and trampling destroyed the seed bank.

In either case, the forest that we now see growing up before us is the community that it is because that’s what is able to be there now. Whatever blows in on the wind. Whatever falls out of the sky from a passing bird. That’s what grows!

As for how stiltgrass enters an area, there are a few possibilities. It is possible, I imagine, that the seeds could be dispersed through the belly of some small creature, a rodent perhaps, and germinate after coming out the other end. Stiltgrass seeds also have “awns” – little bristles, making them something like velcro – and this allows them to stick to the fur of mammals. They could be hitch-hikers on the tawny hides of the white-tailed deer, or on the scrappy pelts of raccoon or possum. Stiltgrass can also grow clonally from her many nodes, and so if they wash downstream, they can sprout wherever they settle. Flooding can move the seeds around, too.

The invasiveness of stiltgrass is overblown and taken out of context. This is my opinion, but it is more than that, too. Flory et. al. 2017 found that “The invasive grass was initially abundant and suppressed native species, but invader decline over time corresponded with succession to native herbaceous species dominance when fire was applied, and to native tree dominance without fire such that after 8 years, the initial effects of invasion were no longer apparent. Thus, our data provide some of the first experimental evidence that while the initial effects of plant invasions can be dramatic, invaders and their impacts may decline over time.” That stiltgrass declines over time has been echoed elsewhere in Cunard & Lankau 2017, too.

Contrary to what is commonly claimed, stiltgrass does not invade older-growth forest ecosystems. It can be ruled out here because the grass does not seem able to thrive where leaf litter accumulates thickly. I see stiltgrass cropping up only where the leaf litter is thin, or bare. Oak leaves, for example, are thicker and tougher than red maple leaves, which are thin and brittle. This is why you’ll see find red maple in the canopy above stiltgrass, but seldom oak. I have also observed where sudden changes in grade or hydrology results in tiny patches where leaves have been swept or scoured away, allowing for a small bit of stiltgrass to grow in the interval. I conclude from from this that leaves smother stiltgrass, forming too great a barrier to allow for seed germination, and only where leaf litter is thin or nonexistent can stiltgrass get a foothold. If my assumption is correct, stiltgrass could be discouraged or eliminated through annual applications of leaf mulch.

Stiltgrass does provide some beneficial ecological services. By holding onto moisture throughout the summer months, stiltgrass orients soil pH towards neutral. Moisture levels and pH are closely correlated (Soil pH Changes Where Wet and Dry Climates Meet), and stiltgrass does a good job of making sure the soil remains somewhere right in the middle, not too wet, and not too dry. Circumneutral soils tend to be more fertile, and soils beneath stiltgrass are high in phosphorous (McGrath & Binkley 2009) and nitrates (Kourtev et. al. 1998), which the stiltgrass seems to consume in large quantity (Kourtev et. al. 1999).

Some of the beneficial aspects of stiltgrass are synergies – happy accidents, if you will. It is known that earthworms are especially abundant in degraded ecosystems such as young woodlots, where soils are more bacterially-dominated. If it weren’t for the living mulch soil cover that stiltgrass provides, it is conceivable that earthworms would leave the soil exposed, denuded — in other words, oxidizing and damaged. Stiltgrass is thus playing an important role as a vanguard or pioneering species, entering degraded woodlots, and building or maintaining soil fertility until succession steers the species community towards increased diversity and perennial herbaceous plants.

I have a friend who is a bonafide turtle whisperer. On a hike together, my friend told me he could find a turtle anywhere. “Really?” I said, dubiously. “Prove it!” So he looked around, and within a few seconds pointed. “See! There’s one right over there!” I looked, and sure enough, he was right. Standing there, camouflaged by leaves, and hidden beneath a bush, was a box turtle. My friend continued pointing out turtles throughout the duration of our hike. Snapping turtles, box turtles, painted turtles, map turtles. You name it, he will find it. Some people possess seemingly mystical connections with the living beings around them.

One time this friend told me he finds the highest density of box turtles among the stiltgrass. Maybe they eat the stiltgrass, I wonder to myself. Or maybe they like the moisture. Whatever the reasons may be, I trust in his observations!

Stiltgrass can act as a protector of native plants in otherwise inhospitable conditions. Driving down a rural road in the springtime, I find dense blooms of bloodroot (Sanguinaria canadensis) growing right up along the edge of the road in full sun, enshrouded in the brown mulch of last year’s stiltgrass stems. As the summer unfolds, and the stiltgrass grows up green and fresh again, the grass will shade the soil and hold onto moisture, replicating bloodroot’s sensitive woodland habitat requirements.

I also see stiltgrass act as protector where I see bluebells (Mertensia virginica) growing in full sun in the middle of a powerline cut. Again, the dead stiltgrass in the springtime forms a mulch around the plants, shading the soil and keeping temperatures lower, as if the bluebells were growing natively in the mesic woodland soil which they need. And again, as the stiltgrass arises green in the summer, she keeps the soil temperatures cool and moist, allowing the bluebells a safe dormancy period, free from the fear of drying out.

Understanding does not come through isolation, but through an exploration of connections. We must look beyond the reductionist lens of western science. There is a bigger picture unfolding. My gripe with invasion biology is that I don’t want to label, defame, and explain away a plant, I want to understand it! Ecology isn’t about right and wrong, it is about interactions within a system. Invasion biology begins with a naturalistic fallacy, and it cannot survive Hume’s guillotine.

Besides – invasion biology is an abnegation of our own responsibilities.

It is important to point out, that “invasive species” exist first and foremost where land has been degraded by humans, or is being kept in a constant state of disturbance by human activities. The exception — where species introductions do have dramatic and exaggerated effects — are ecosystems like those of islands, where vast expanses of surrounding water act as natural barriers to what would otherwise be the ongoing flow of an open system.

Despite anthropogenic factors being the number one cause of invasions, a look at the Global Invasive Species Database reveals something interesting. Homo sapiens isn’t listed among the top invasive species on this planet. We don’t even make the Top 100 Worst list. In fact, we aren’t listed at all! What’s up with that? The whole thing reeks of politics!

On an animist level, every living thing is being and breathing and beating and the web of life is constantly spinning and unspinning. Each and every present moment is a mere flicker in the universal fires of change. If we could speed up time, it would flow with the turbidity of a waterfall. Who are we to say that a species does or does not belong to the place where it is found? The notion of a native species is conceptually useful, I admit, and I use it too. But under scrutiny – on a genetic level perhaps – the old nativist ideals fall apart. Rapid evolution, for example, has resulted in American stiltgrass populations which are different from their east Asian progenitors in flowering-times, fecundity, size, and vigor (Flory et. al. 2012). In other words, stiltgrass has naturalized and is developing its own genetic distinctions. We are always adapting to the novel conditions we find ourselves in. Take a species out of its native country, wait a few generations, and it isn’t the same anymore.

The whole question of native vs. exotic reminds me of my own heritage. How do I fit into this North American continent when my ancestors came from Europe? I come from a lineage stuck between worlds, no longer European, but not fully American either. The story of stiltgrass is the same kind of story. We cannot step backwards in time, nor can we erase the past. We must make do with the situation we’ve inherited, learning to cooperate, and learning to live in peace. That is why I cannot get on board with invasion biology. It is a philosophy which urges us to wage a war on nature. It condones the use of poisons. It condones the use of chainsaws which lay to waste without use. It compels the wanton slaughter of animals deemed harmful. It condones the deceitful use of Judas goats, and hunting by helicopter. It condones what is an analogue for dehumanization – a dreadful devaluing that cuts into the core of our own hearts. It calls for literal genocide. That is unconscionable.

But I am being too laissez-faire, I hear my critics say. “We must take responsibility for nature,” they say, and find ways to “control the invasives.” Well, I’ll go ahead and answer that charge, providing here my own solution to the “stiltgrass problem.” One which doesn’t use poisons. One which doesn’t devalue the plant. One which doesn’t call for genocide.

Something that is great about stiltgrass is that as an annual which grows only during the warm season, when it dies back in the autumn and winter it creates a wonderful, straw-like mulch. This mulch is ideally suited for burning. Fire introduced to stiltgrass mulch moves in cool-burning, quick fire. Paradoxically, the presence of abundant stiltgrass in rich, shady, degraded habitats provides for its own solution – fire management!

Through the burning of stiltgrass, we can:

• Clear away weeds and other pesky brambles such as multiflora rose, vine honeysuckle, and other “offenders.”
• Conduct burns in areas that would be otherwise too moist to burn without the presence of stiltgrass. This is an advantage because the moist areas are often the most overgrown, inaccessible, and fertile.
• Move forward ecological succession through the opening up of habitat, making room for native perennials, for example.
• Add biochar to the soil, creating substrate for soil nutrients and micro-organisms, facilitating a higher cation exchange capacity, and tending towards a soil chemistry which is more circumneutral in pH.
• Through neutralization of soil, increase the bioavailability of calcium thus stimulating root, tuber, and fruit growth of nearby plants, as well as phosphorous.
• Use fire to further ecological succession, favoring fire-tolerant thick-barked native trees such as oaks and hickories, perennial grasses, as well as perennial herbaceous plants which overwinter below ground in corms, bulbs, or tubers.
• Use of fire over consecutive years will diminish stiltgrass and promote the growth of others.

The important thing to understand about stiltgrass in order to control it is its timing or phenology. As essentially an annual warm-season grass, stiltgrass will not germinate until early summer. This is after the spring ephemeral bloom. It is also after the time that many perennial seeds will germinate. True, burning stiltgrass clears away last year’s stiltgrass thatch and allows stiltgrass to grow back even thicker and lusher. But that heavy stiltgrass thatch is not just a barrier to its own germination — it is also a barrier to native seed germination. Therefore, with the thatch cleared through burning, over time the stiltgrass populations will lessen as other perennial species, able to re-seed themselves now, begin to outcompete the annual stiltgrass.

Now, here’s a video of some stiltgrass burning I did last year. I burned stiltgrass along a floodplain edge beneath black walnut trees, and also in a larger open area where stiltgrass was growing among porcelain vine (Ampelopsis brevipedunculata), mile-a-minute weed (Persicaria perfoliata), and multiflora rose. Last year’s burn was successful in clearing out a lot of this brush, and there was more grassy growth this year, so I was able to repeat the burn even cleaner than last time, plus I expanded the burn patch further down into the floodplain.