Wanted: A Few Good Herbivores

If you encounter a book or article that claims that, surprise!, invasive species aren't such a big problem after all (a few were written over the past decade), you'll probably find no mention of herbivory. They'll say that invasive plants are being falsely maligned, because actually they do wonderful things, like provide berries and nectar for wildlife. But it's to the plant's advantage to have its flowers visited and its berries consumed. What the plant doesn't "want" is to be eaten, and therein lies the problem with plants that become invasive. For whatever reason, be it an invasive's chemical defenses or ingrained dietary habits, the wildlife tend not to eat them.

Nature depends on consumption to keep things in balance. We love nature for its beauty and variety, but behind the scenes there's a whole lot of mastication going on. Take away predators and the deer population explodes. Introduce a new plant that the wildlife won't eat, and there's potential for that species to make habitat less and less edible as it displaces the natives. To fill this void in consumption, people have had to play the role of herbivores. What we do at Herrontown Woods, as we cut down dense groves of winged euonymus and other nonnative invasive shrubs, is to play the role of the missing herbivores, using our loppers for teeth.

There's some pleasure in the work--pleasing vistas created, serendipitous discoveries. But all things being equal, it would really be nice if the resident wildlife could show some flexibility in food preferences and fill the void in consumption. Invasives, after all, represent a huge, untapped food source for any animal willing and able to broaden its palette.

Given how much work it would be for humans to play the role of herbivores in the forest, any evidence of wildlife gaining an appetite for invasive plants stirs some hopefulness.

For instance, an invasive honeysuckle shrub was recently found stripped of its leaves. A closer look revealed something had been hard at work, its mandibles outshining our loppers: the caterpillar of a snowberry clearwing moth, also known as the "hummingbird moth" or "flying lobster", for its capacity to hover in front of flowers as it sips their nectar. Maybe if we had more summer wildflowers for the adult moths to feed from, their caterpillars would help control the populations of bush honeysuckle in Princeton's preserves. Nice to think, anyway.

And what's this orange plant growing on a dense expanse of invasive mugwort that grows as a monoculture along the gas pipeline right of way in Herrontown Woods? Dodder is a parasitic plant with little capacity to gather energy from the sun. Instead, it wraps itself around other plants and sucks out their juices.

Usually, its impact is small, but this must have been a particularly good year, because a sizeable patch of mugwort was sucked dry.

If only we could get the dodder (genus Cuscate) to preferentially neutralize the mugwort all along the right of way, some diversity might return. Again, a nice thought and tall order.

A new invasive trying to gain a foothold in Princeton is mile-a-minute vine, with a distinctive triangular leaf, a prickly stem, and a growth habit to match its name. Another post shows how invasive this annual vine can be , on farms just outside of town. Fortunately, after weeding out a small population back in 2007, I know of only two patches currently growing in Princeton, still small enough to control and hopefully eliminate altogether.

One's at the Princeton Battlefield. This year's growth was pulled out in early summer, and when checked in late August, the patch had only managed to produce a few leaves, all of which were being very effectively munched on by a weevil intentionally introduced to the U.S. to bring this rampant new species under control.

Ah, I concluded, to control mile-a-minute vine, simply reduce the patch in early summer, leaving enough for the weevils to sustain their population on. Their appetites appeared to be sufficient to prevent any flowering or fruiting that could lead to the patch spreading elsewhere.

Nice concept, but it wasn't working at the other site, down along the driveway into Rogers Refuge, where the vine had sprung back up, flowered and fruited, undeterred by the minor nibblings of the weevil. That patch had to again be pulled out by hand.

Another discovery was the work of the Ailanthus webworm moth, which had completely defoliated a young tree of heaven near the parking lot of Herrontown Woods. The moth, like the tree, is an introduced species.

If you have flowers like boneset growing in your backyard, you may be helping the adult moths to prosper.

Here again, though, the larvae have thus far been seen only on very young trees, with larger ones largely left untouched.

These are glimmers of hope, sprinkled across Princeton. It will take some concerted mastication by as yet unnamed herbivores to stem the tide of rapidly spreading species like porcelainberry, callery pear and stiltgrass--a giant uneaten salad that grows by the year. A little salt and pepper, perhaps?

Bamboo at Princeton Battlefield Gets its Summer Cut

This past Saturday, four of us gathered for a well-timed intervention at the Princeton Battlefield. The Friends of Princeton Battlefield had cut down a patch of bamboo in the spring, but the roots had quickly sent up a new crop of shoots--essentially foliar solar panels that would quickly begin resupplying the bamboo's powerful root system. By following up and cutting the new shoots, we deprived the roots of any return on their investment in new infrastructure. This is the third year we've done this, and each year the job gets easier. A massive stand of bamboo has been reduced to modest sprouts easily managed.

Thanks to volunteers Jill Warrington, Andrew Thornton, and the leader of the Friends of Princeton Battlefield, Kip Cherry. My participation was a bit of outreach from the Friends of Herrontown Woods, on the other side of town.

Mile a Minute--A Wave Growing Across NJ's Countryside

You can spot it a mile away. Early summer, and already this annual, thorn-covered vine called Mile-a-Minute is rising like a wave along fencelines in New Jersey's countryside. Thus far, in my ramblings around Princeton, I have found only two tiny patches--at the Battlefield and along the driveway into Rogers Refuge--both of which have been knocked out the past two years. Is this sort of early intervention and annual followup worth it? The answer becomes abundantly clear just outside of town, halfway to Hopewell, where Mile-a-Minute vine is demonstrating just how much of a prickly menace it can be if not caught early.

It's a plant that seeks to be seen everywhere, and with all the other players on the plant scene. Here it is growing up a tree,

and sprawling over another invasive, garlic mustard.

Even those thistles with their prickly personalities aren't off-putting for a Mile-a-Minute vine.

It's said to have been an accidental introduction from eastern Asia via the nursery trade, originally gaining a foothold in York County, PA, in the 1930s and spreading from there.

Rampancy rules in this photo, as mile-a-minute swarms an autumn olive--a highly invasive shrub. When mile-a-minute's around, the curtain doesn't fall on other plants, but rises, in a wave of triangular leaves.

Here's Mile-a-Minute chasing the growth tip of a blackberry. Check back in a month to see who won the race.

Here, a privet's growing a prickly skirt.

Those pink flowers are Canada thistle, invader of many a garden bed, which is about to meet its match.

Long-time ubiquitous invasives, multiflora rose and Japanese honeysuckle, are joined by Mile-a-Minute.

You'd think perennial vines like wild grape would have a big advantage over an annual vine that has to spring anew from the soil every year, but Mile-a-Minute is looking up to the challenge.

Note the holes in the Mile-a-Minute leaves. Those are most likely from a weevil that was introduced as a biological control. The hope is that the weevil will become numerous enough, and consume enough triangular leaves to slow the wave of Mile-a-Minute engulfing the countryside.

Thus far, the Mile-a-Minute looks undeterred, growing over the slowly maturing fruits of wineberry,

and the pale stems of native black raspberry.

Beyond any ecological impact of such rampancy, it's interesting to reflect on the aesthetic and emotional impact of seeing a landscape being overrun by Mile-a-Minute. A healthy native prairie, for example, teaming with many species of grasses and wildflowers, all reaching for the sun with no inclination to crawl over one another, gives a feeling of striving, freedom, diversity, peaceful cohabitation, tolerance of one species for another. In contrast, a vine like Mile-a-Minute creates a smothering effect, a sense of clutter and thorny entanglement, a suppression of difference, an oppressive dependency that plays out as a punishment for any plant that dare reach a sturdy stem for the sky.

Hands-On Learning About Invasiveness in Plants

Environmental science teacher Jim Smirk brought his kids outdoors this spring to do some hands-on learning at the Princeton High School's very own ecolab wetland. Most people would call it a detention basin, but we planted it long ago with native wetland species that thrive on the beneficent, dependable offerings of the high school's sump pump. Yes, a lowly sump pump provides the consistent water flow that drives this lush community of plants. Without it, most of the plant species, along with the frogs and crayfish, would die out the next time a long drought came along.

Jim enlisted me to provide some history on the planting to three of his classes, and also to explain why this manmade detention basin does such a good job of hosting wetland plants and animals. Like any garden, even a fairly wild one, it still needs intervention to maintain balance, since some of the native species tend to take over. Cattails, lizard's tail, and the native sunflowers spread aggressively underground, while the willows pop up in new places and quickly grow, hogging the sunlight.

Some of the more adventurous students donned waders and began digging up short- and broadleafed cattails so that some of the less aggressive sedges and wildflowers wouldn't be overwhelmed.

Others cut back willow, and removed a non-native plant called starwort that gained a foothold a couple years ago.

The students showed a lot of spirit, and were surprised that working in the mud could actually be fun.

Thanks to Mr. Smirk and his environmental science students for helping keep this wetland thriving right next to Princeton High School.

When Regulation Simplifies Our Lives

Many reflexively contend that regulation makes life harder, more complicated and constricting, and less convenient. And yet, here, in a packed room of people who wanted to learn more about invasive species, was ample evidence of how complicated an unregulated world becomes. Though many imported plant and animal species do not become invasive, the ones that do become a problem that each individual is then left to contend with. Uncontrolled transport of wood for packing crates coming from Asia, for instance, allowed the emerald ash borer to take hold in Michigan, and spread across the eastern U.S., causing millions of homeowners inconvenience and expense as the ash trees in our yards succumb. 

The same holds true for recycling. Because manufacturers can package their products in an endless variety of plastics, metals and papers, each one of us is then imposed upon to compare each piece of empty packaging to a long list of do's and don't's--a daunting project for even the passionate recycler. Packaging is geared towards maximizing purchase and convenience of consumption, leaving in its wake a hugely complex post-consumer dilemma that complicates our lives and fills our landfills and oceans with trash. Why not, instead, require all packaging be widely, easily, and demonstrably recycled, and expect manufacturers to use their ingenuity to figure out how to comply?

These are the sorts of quandaries that pack the community room at the library. If there were no food safety standards, we'd probably be cramming into the library to find out how to identify diseased beef at the unregulated supermarket, just as we'll each be seeking help to deal with the complicating, destabilizing consequences of climate change.

Regulations, if done well, can greatly simplify our lives. That truth needs to be repeated on a regular basis.

A previous post dealt with some aspects of invasive species in Princeton. 

Invasive Plant Species in Princeton

This Monday, May 22 at 7pm, the Princeton Public Library will host a presentation on invasive species in Princeton by Mike van Clef, of the NJ Invasive Species Strike Team. There will also be representatives of FOPOS and DR Greenway participating. Princeton municipality hired Mike to develop a report on invasive species in Princeton preserves, and in 2016 he and two interns worked through the summer on invasive species control. Because of the massiveness of the problem, they focused on emerging species--those whose populations are still small enough that a summer's worth of control would make a difference. 

We may look back on 2016 as a pivotal year, when the town began investing in invasive species management, much as 2000 marked the beginning of professional deer management in town. 

Although it may sound self-congratulatory, another important date in Princeton's history of invasive species management would be 2006, when the Friends of Princeton Open Space hired me as their first Natural Resources Manager. 

When I arrived in town in 2003 on the coattails of my wife's appointment to the Princeton University faculty, a couple things quickly became obvious. First, Princeton had done wonderful work preserving land for open space. Second, the open space itself needed a lot of work. Though the trees in Princeton's woodlands were mostly native, the understory vegetation was often dominated by nonnative, invasive plants. Stiltgrass, honeysuckle and privet, to name but a few, had filled the void created long ago when the diverse native understory had been plowed under, back in Princeton's agricultural era. In the decades since, the native trees had rebounded, but the understory had either not come back, or succumbed to heavy browsing pressure from deer.

Because wildlife tend not to eat the leaves of nonnative plants, their proliferation in preserves renders the habitat largely inedible. Yes, birds can eat the berries of nonnative shrubs like honeysuckle, but if the insects and other wildlife aren't eating the leaves, then much less of the solar energy captured in the plants can move up the food chain. 

I proceeded to make the case that Princeton could expand its effective acreage of open space through management for native species. As most readers know, I've been leading workdays and nature walks ever since, for six years as an employee of FOPOS, and more recently as president of the Friends of Herrontown Woods (FOHW). Highly motivated volunteers like Tim Patrick-Miller and Andrew Thornton, and more recently Kurt and Sally Tazelaar at Herrontown Woods, have had a positive impact over time. Meanwhile, FOPOS has sustained its Natural Resources Manager position--having just hired the fourth to hold that position--and continues to do invasive species removal at Mountain Lakes Preserve. After so many years of nonprofit, largely volunteer efforts, to finally get municipal support through Mike's crew this past summer was a real boost that we hope will continue.  

It's important to note that Mike van Clef's study of invasive species in Princeton is limited to parks and preserves owned or managed by the town. There are large expanses of open space owned by the state (Princeton Battlefield and DR Canal) and by the Institute for Advanced Study (the 600 acre Institute Woods). Portions of the Battlefield and the DR Canal are being overrun by porcelainberry (in photo), which barely registers in Mike's survey, and mile-a-minute vine is beginning to show up there as well. I've been trying to help fill a void in management, co-leading workdays at the Battlefield and, in the proactive "early detection, rapid response" tradition, dealing with two small infestations of Mile-a-Minute in town before they become unmanageable. Another nonnative plant that's spreading rapidly, both in people's yards and in nature preserves, is lesser celandine (a.k.a. fig buttercup). It can only be controlled in the spring, long before summer interns begin work. Ideally, a town-wide coordination to manage invasive species would be developed.

The town's investment in invasive species control comes at a critical time. With the emerald ash borer (another highly invasive introduced species) poised to decimate Princeton's most numerous native tree, large gaps will be created in our forest canopy, allowing light to penetrate to the understory. Princeton's long investment in deer culling has allowed native shrubs like spicebush to make a comeback, but in many woodlands, the understory is dominated by nonnative shrubs and stiltgrass. Wildlife have evolved over millenia to eat native species. It's a question of whether edible natives will capture that extra sunlight in the understory, or the privet, winged euonymus, honeysuckle, barberry and Photinia. The foodchain depends on our intervention.

The primary argument for habitat management remains that, by improving the quality of habitat, Princeton effectively increases the functional acreage of open space. This is true not only for wildlife but also for people. Controlling invasive species also makes the human experience in preserves more rewarding. As we've cut down invasive shrubs at Herrontown Woods, we've not only made more sunlight, water and nutrients available for native species to prosper, but also have opened up pleasing vistas and made the woods more navigable. 

The problem of invasive plants may seem overwhelming, but we can take our inspiration from the deer, who transform landscapes through the cumulative impact of browsing here, there, and everywhere, one mouthful at a time. The pioneers, too, thought the continent too vast to ever tame. Though their goal wasn't exactly to increase native plant diversity, they showed how steady effort makes a difference over time. Ideally, professionals will complement existing volunteer efforts, and the locals who know the preserves best will help steer the professionals' interventions. 


At Monday's presentation, there will also be discussion of a list of invasive species that people are being discouraged from planting. It's a very long list, and I wish it could better reflect the broad spectrum of invasive behavior we see in the field. One reason the list is so long is that, though many of the species on the list may not be found spreading into Princeton's nature preserves, history shows that invasive behavior in nonnative species may not become manifest until many decades after they've been introduced. Chinese silver grass (Miscanthus sinensis) is a case in point. Though it has yet to spread to Princeton's Tusculum meadows, it is now posing a big problem for meadows at Duke Farms up in Hillsborough. The flyer for the library event includes a photo of butterfly bush, which I've never observed exhibiting invasive behavior. Monday's presentation may help put local observations in a broader context.

Update: Full house for the program! Good to see.

A Garlic Mustard Success Story from Michigan

Back in the 1980s, while I was accumulating credits for a masters degree in water quality at the University of Michigan, I did some academic moonlighting and took an "expository writing" course taught by Alyce Depree. She had us adopt pseudonyms (mine was Snupulus Lupulus), fed us a steady diet of George Orwell, and had us write and rewrite 2-page essays. It was a wonderful, validating experience.

Last summer, heading back to Michigan to play a jazz festival, I reconnected with her. Out of the blue, she told me the inspiring story of her long but successful battle with garlic mustard--an introduced species that has displaced trilliums and other native wildflowers in the woodlands where she lives in Holland, Michigan. She later wrote up an account of her experience.

I'm posting this when just a few blooms remain, but you should still be able to find it growing along the fringes of your yard, or in a woodland nearby. Perhaps you'll be moved to action, in your yard and beyond, as Alyce was many years ago, with heartening results.

Here's her account:

Hi, Steve...You've caused quite a chuckle here this morning...so few people for so long cared about what was occurring in their woods on the west side of the state that my cousin and I spent almost as much time encouraging ourselves not to give up as we did actually picking! The tables have turned (mixed metaphor), however...now in the spring the local churches (of which there are many) organize their congregants and Sunday school kids to go over various ground areas and parks in the Holland area...that is making quite a difference.

In my cottage area along the lake, and my cousins', we noticed sixteen years ago that our lovely banks of trillium in the woods simply no longer appeared in springtime. What we had instead was this aggressive leafy plant with cute little white blooms that grew higher and higher during the spring until, by June or so, could be four feet tall and going to seed...it almost looked like phlox, except that the blooms were single, not developed into bunches or clumps. So we did some research, and discovered what it was called and how it was edible (yuck) and that our venerated forefathers had brought it with them from England, mostly, as it would give them something green...and last and last and last. Which it does. It's a two-cycle plant; first year establishes the root, second year establishes and spreads (by "popping" out) the seeds every time wind or an animal comes in contact to move the branches. Each mature second-stage plant can have hundreds to a thousand seeds. It is generally the first plant to begin showing after winter...spreading out quite quickly with many leaves that cut off the sunlight from surrounding and still dormant plants or seeds. Additionally, the root...which resembles a skinny parsnip...exudes a poisonous substance which makes the soil unfriendly to wildflower growth in general AND also strips the protective coating off tree roots...so soil diseases can then attack the trees.

 We found that, while people can be casual about wildflowers, they aren't casual about their trees; however, they are "terribly busy." Anyway, my cousin and I decided we'd rid ourselves and the immediate area of garlic-mustard. We figured we could do a five or six property area...talked and talked with the owners but didn't really convince them, so then took on the job ourselves. After experimenting with RoundUP and discovering not even that would kill the plants, and learning from internet that the state of Wisconsin had been trying to get rid of them with no luck, we began with local college kids, paid them $12 per hour, lunch, and snacks, and then joined them ourselves, pulling and digging (you have to get the root!) for about ten days. We filled hundreds of 30-gallon black plastic bags with the ill-smelling plants, let the contents rot for a month, and then gradually put them out for garbage pickup.

 We picked and pulled the five properties for the next ten or so years..."harvest" getting less and less (the seeds last 5 years in the ground)...one owner gets his own grandchildren to pick their woods now...we continue to work four properties and now only get about 15 bags, max. We figure we're down to just maintenance now plus some plants from seeds borne by the winds. The past three years we have not hired anyone to help...just do it ourselves and are glad for the exercise. The trillium is back and glorious. Also a wild yellow ground lily and jack-in-the-pulpits. Amazing how sixteen years flies by....and no chemicals, too.

(Thanks to Alyce for sharing this account!)

Photo below: Garlic mustard extending into the woodland below Quarry Park in Princeton.

15 Flowering Dogwoods Rescued from Smothering Vines at Princeton Battlefield

Saving legacies is what Princeton Battlefield is all about, and one legacy we sought to save during a big workday organized by Kip Cherry were flowering dogwoods planted for the nation's bicentennial in 1976. I do most of my habitat restoration work at Herrontown Woods in eastern Princeton, but have been visiting Princeton Battlefield periodically to help tame bamboo monsters, care for native chestnuts and prevent vines from completely smothering the dogwoods. Having ten able and spirited volunteers at this year's Battlefield Society's Clean-up Day made real progress possible.

Kip Cherry (front left) began the afternoon with a moving description of the great battle that took place there in 1777.

Ten of us then headed across Mercer Street to liberate the flowering dogwood trees lining the edge of the field. The dogwood flower buds, poking through the drapery of vine growth, provided inspiration, with their promise of beauty in the spring, and nutritious berries for the birds in fall.

This was the curtain of vines we cleared away with loppers and pruning shears, while dodging poison ivy and the thorns of multiflora rose.

Here's a "before" shot, showing porcelainberry draped over three dogwood trees. (photo from last fall in a previous post)

And here's the "after" shot, taken from underneath the rescued dogwoods. We worked to create an open space between ground and lower limbs so the vines cannot easily climb back up.

Thanks to our brave and skillful crew, who came from near and far to liberate fifteen dogwoods over the course of three hours.

I liked this pose when the work was done. As always happens on workdays, there were good conversations to go along with the physical work. I gained some Veblen House-relevant information about Long Island and Connecticut, and heard some positive testimonials about electric cars like the Chevy Volt, which combines 60 mile battery range with a backup gas engine. One owner said she'd spent only $9 on gas since last summer, and hadn't noticed any rise in her electricity bill from charging up the car at home. While restoring some history, it was good to hear the future in the form of electric cars might be at hand as well. The same thinking goes into saving legacies, whether they be dogwood trees or the world's climate.

Senator Kip Bateman and Assemblyman Reed Gusciora dropped by to help out.

Here is Kip Cherry's summary of the day:

"Our Clean-up Day was a big success! The sun peaked out, and from all reports everyone had a great time, the Park looked a lot nicer when we were done, the CWT t-shirts were well received, and the Sierra Club came through. Senator Bateman and Assemblyman Gusciora both arrived and put their shoulders to the wheel. A large group of kindergartners picked up fallen sticks, while others removed invasive porcelainberry vines from dogwoods, cut down bamboo, and cleared encroachment along the pathway to the Quaker Meeting House. Special thanks to Kim Gallagher and Steve Hiltner for leading teams, and to Gary Nelson and Randy Riccardo for their hard work!"

Porcelainberry: the Vine that Ate Princeton

Here it's Friday of National Invasive Species Awareness Week, and nary a post about invasive species!

First, readers should be aware that there are contrarians out there, writing books, articles and opeds, trying to deny that invasive species are a big problem. It's fascinating to analyze their mental gymnastics and deceptions, which are similar to those used to deny the reality and danger of climate change. I've picked apart their faulty logic in posts that can be found at this link.

Now, on to our porcelainberry tour of Princeton. You won't find it in shady areas, where other invasives like stiltgrass, garlic mustard and winged euonymus thrive. Rather, porcelainberry threatens to smother all of those sunny openings and edges that shade-intolerant plants depend on for survival. Porcelainberry is related to our wild grape, but much more aggressive. Your first impression will be, "What lovely multicolored berries!"

Your second impression, as it climbs up the stems of your shrubs, like this elderberry, might be, "Oh, a little rambunctious, but those berries are so pretty!"

Your third impression, as it turns your yard or park into a monocultural topiary, will be more along the lines of, "OMG! HELP!" No, this is not kudzu growing along a freeway down south. This is porcelainberry winning a modern day Battle of Princeton, with stealth and persistence far beyond anything we distracted humans might muster.

This is what a nearby patch looks like in December, just down the road from the Princeton Battlefield, along Quaker Rd between Mercer and 206. Invasive vines and shrubs can seem less overwhelming in winter, which is actually a good time to remove them. In spring and summer, though, all that growth energy can be intimidating.

And this is what porcelainberry is doing to the sunnier portions of our lovely nature trail off the DR Canal Towpath near Harrison Street. The blackbirds may say hello to the berries, but it's bye bye to the diversity of native wildflowers underneath that foliar blanket.

Turns out porcelainberry's a soccer fan. Here it is in the cheap seats at Princeton University's Roberts Stadium, at one end of the field,

and at the other.

Here it is (light blue and pink berries) in that "second impression" stage, climbing over a honeysuckle shrub (red berries) at Quarry Park. Give it a few years and it may reach the "OMG" stage.

I haven't seen much of it in eastern Princeton yet, but we'd be smart to keep an eye out and remove it before the berries mature.

Otherwise, sunny edges everywhere will look like these hapless flowering dogwoods, planted at Princeton Battlefield in 1976 for the nation's bicentenial, and now struggling to survive beneath a spreading blanket of porcelainberry.

Note: You can help liberate the dogwoods from the porcelainberry and other vines on Saturday, April 1 at 1pm. I've been collaborating with the Princeton Battlefield Society on invasive species work for the past several years, and will be leading a group to preserve the dogwoods that line the field on the north side of Mercer Street.

Another group of volunteers will be continuing the multi-year effort to reduce the bamboo clones near the Clark House, which we're actually having considerable success without herbicide. 

For purposes of identification, here are a couple closeups of porcelainberry. The berries are distinctive, with different shades of blue, red and white.

The leaves are easily confused with wild grape. This photo shows how variable is the shape.

I hope everyone's having a happy National Invasive Species Awareness Week. We'll end with a short Q and A:

• Are all nonnative plants invasive? No. Nonnative refers to origin. Invasive refers to behavior.
• Why are invasive plants invasive? Oftentimes, it's because the native insects/deer, etc don't eat them, giving them a competitive advantage. To regain the balance we lost by introducing species that evolved elsewhere, people end up having to be the herbivores, wielding saws and loppers.
• One nice thing about invasives? They get us out in the woods for workdays.