Invasives – Towards the Moon or To the Sun

The Greedy Weed

As we are a few days from Halloween and thus well into the Scary Season, I write of a vine of legendary horror. No, it isn’t Audrey II, the alien plant that devours people, but it’s close. It is kudzu, the Vine that Ate the South! <cue ominous chords>

Okay, that’s slightly overdramatic, but you can safely add it to the list of imports that “seemed like a good idea at the time.” Like many inspired catastrophes of good intention, importing this rampant leguminous vine from Asia was intended to be an easy fix for another human-caused calamity, soil erosion. And it certainly covers up the gullies and bare slopes like nobody’s business. The problem is, kudzu isn’t that great at holding soil. True, its vines lengthen at the stunning rate of a foot per day, but the thick taproots don’t spread wide and fine to hold soil as those of grass might. Once rainwater collects under the vines, there is little to keep the soil from washing away.

The climate in the South is substantially different than that of Japan, where shorter growing seasons and colder winters moderates the growth of the vine. In the land of hot summers and mild winters, the plant turns invasive, flowing over fields, over trees, over buildings…anywhere a vine can go. Kudzu crowding vines deprive everything beneath them of sunlight, killing forb, grass, shrub and tree.

Kudzu has been put to various uses in an effort to make a positive out of such an overwhelming negative. The leaves make a highly digestible cattle forage. Some people make compost; others craft baskets or wreaths from the vines. But the usage of kudzu is negligible compared to the sheer productivity of the plants. This menace has covered millions of acres across the Southeast, and as far north as Nova Scotia and westward to the Pacific coast.

Apart from seeing blankets of the weed, covering field and forest, from the safety of the family truck, my first experience with kudzu came when I was eight or nine. My Mom and I tramped through a pine stand one night, trying to connect with some foxhounds that had strayed from the pack. We lit the forest floor with wheat lamps (a powerful light used by miners and coon hunters alike) to guard against entanglement or envenomation. As we progressed, I gradually noticed a change in the vegetation around me. There were fewer briers, and most of the abundant saplings were dead and leafless. Then, our lights picked what appeared to be a fuzzy wall fifty yards ahead, stretching in either direction as far as our lights would shine. We looked up and saw the unnerving ceiling of the same gray-brown material, held up by dead pine trees like tent poles.

We reached the wall of vine and dead leaves, and I looked to Ma to see what to do. The vine tangle stood between us and the truck, and there was no telling how far we’d have to follow this dead barrier before we struck another open trail. Finally, she put down her light and reached into the wall, pushing the vines apart just enough to form a tunnel. She directed me to climb up into it and continue to dig through. I remember the dead mass supporting my weight and being thick enough that I was completely encased in dry leaves before reaching the first green ones. I broke through to the open air and tumbled out the other side before turning and helping Ma crawl through. With the green wall at our backs, we waded through a smothered field before reaching the dirt road.

My encounter with the backside of kudzu occurred a couple of weeks ago when I visited a newly-purchased hunting property. It had many of the common invasives – Chinaberry, stiltgrass, tree-of-heaven, sericea, and so on – but by far the most visible issues were the mounds of kudzu, topping the smaller trees and coiling upwards towards the tallest oaks. I think the landowner is aware that the land he bought is a “fixer-upper.” I’ll tell him the options: burning or mowing to reclaim conquered territory, followed by herbicide to strike at the roots, the only way to permanently kill this scourge. But I’ll warn him to be prepared for a multi-year campaign. And I won’t say what I’m thinking: Better you than me.

Meet the New Orb-Weaver…

This weekend I received texted photo of a spider, with the question: “Friend or Foe?” What she meant, of course, is whether the arachnid posed a danger to her. The picture she sent was that of a Joro spider (Trichonephila clavate). I told her it wasn’t dangerous, but in truth it requires a more complex answer.

Until recently, I could comfortably identify the big spiders around my house as either the garden or writing spider (Argiope aurantia) or the golden silk orb weaver (Trichonephila clavipes). When late-summer spider season hit and webs were being spun in every available tree and porch pillar, the usual suspects aren’t in attendance. Instead, the Joro spider, an Asian native, has set up shop all over Athens and throughout our woods in a neighboring county.

In the Fall of 2014, a fellow in Madison County, Georgia, sent photos of a strange spider to the Department of Entomology at the University of Georgia. This is the first record of the Joro spider in North America. They probably arrived, as so many invasives do, in packing material for goods shipped across the ocean. Since then, they have expanded their range across the Piedmont of Georgia and South Carolina. Given that the spiders lay egg sacks with hundreds of eggs (up to 1500!), it is easy to see how they overwhelm the other large orb weavers in the ecosystem.

My ecologically-aware friend was incensed. “…are we just meant to let them naturalize, or are we supposed to be coming up with ways to get rid of them?”

Good question. If one species takes over a niche from another species, that is cause for a naturalist’s concern. Unfortunately, unless the usurper causes some economic harm, you aren’t likely to have any of the Powers That Be care enough to devote resources to it. Not that there is likely to be a way to combat this species that doesn’t threaten all other spider species.

No, I think we will see the Joro continue to spread and naturalize. They will capture insects with as much efficiency as their predecessors, and their bites are just as harmless to humans. Whether the transition of arachnid power will impact the ecosystem beyond displacing some species remains to be seen.

Links:

Spiders in Georgia: Identify the spiders you find.

Curse of the Starling

If I became governor of Hell I would reserve a special room for Eugene Schieffelin and his minions in the North American Acclimatization Society, the idiots who thought it would be nice for all the birds mentioned in Shakespeare’s works to be represented in America. In the 1890’s he released around 60 starlings into Central Park. Because of one single line in Henry IV, an estimated 200 million of the aggressive little bastards currently occupy North America, wreaking havoc on native bird populations.

Why such antipathy for these morons? Why not put in Etienne Trouvelot (who introduced Gypsy Moths) or whoever shipped the wood that contained the fungus that annihilated the American Chestnut? Because Schiefflin and his cronies went out of their way to perpetrate their crime, and for a silly reason.

Humans have been bringing pests from one land to another since they first commenced to roam, and many native species and a few ecosystems have paid the price. Many are completely unintentional, from fire ants to zebra mussels. Some seemed like a good idea at the time, like kudzu or cogon grass. But Schieffelin’s crowd were whimsically Anglophilic.

Dreamers are fine. But sometimes their dreams can become nightmares.

Rogue Pears

As I write this, white blossoms are popping out behind my house — an old nemesis sneers at me. The Rogue Pear.

The callery pear (Pyrus calleryana) is an Asian native brought to the US in the 1960s. Why? The pears are small, round, and inedible. The flowers fill the air with a sickly-sweet odor. The trees are densely limby and prone to splitting in bad weather. Like many fast-growing trees, the callery pear is short-lived, lasting only a couple of decades or so. So why has it turned up in every doctor’s office park and subdivision? Three things: beautiful foliage– deep green in summer, leaves turning blood-red or wine-dark in the autumn; an explosion of flowers late in winter; quick growth to a bushy, symmetrical silhouette.

Horticulturalists created a number of cultivars, the best-known being the ‘Bradford’. We removed the thorns, we straightened the forms. As a useful biproduct, these cultivars couldn’t reproduce. You plant Bradfords, and they stay where you put them.

But, in our great and unmatched wisdom, we kept tinkering. Each cultivar had slightly different properties. Different colors, stronger limbs. And then it happens. One cultivar is used to landscape a new strip mall, and a different one dresses up an office park down the street. Some local bees visit one and then the other. It turns out that different cultivars can fertilize each other. And these new seedlings exhibit the attributes of the original, wild pear: able to grow on a wild range of soils, able to seed prolifically, and armed with thorns that can punch through a truck tire. I call them rogue pears, when I don’t use stronger adjectives for them.

It’s a contagion the scope of which you aren’t likely to notice until late winter. Come February until April, these innocuous green trees suddenly blaze white in floral profusion. My corner of the county is pretty well infested; a mere 10 years after being fallow, the neighbor’s field is a young forest, with 8 out of 10 trees being pears. But I didn’t have any inking of realize how widespread the problem was until I was a couple of hours away, driving on a highway skirting the Fall Line. In the pine plantations on either side, the midstory was packed with pears bedecked with their white blossoms. Some quick research showed the rogue pear has popped up in most states east of the Mississippi, and it has a foothold in several western states as well.

Everyone knows about kudzu. You may have heard of Chinaberry or privet or tree-of-heaven. Now that pear is on your radar, maybe you’ll start seeing it come the end of winter.

Maybe, hopefully, you’ll choose native trees for your next landscaping project.