Are earthworms to blame for missing understory?

Hi everyone! I'm new here and am coming with lots of burning questions! We bought a 43 acre farm on a hilltop in KY. I've noticed in the forested part that there is very little understory. At first I thought the invasive bush honeysuckle was choking out the baby trees but then remembered the invasive earthworm problem - where they eat up all the leaf mold, completely changing the dynamics of the forest floor so most of our native species (that rely on leaf mold) cannot live or sprout, making barren understories.

Since I'm on a hillside, the runoff (we get a lot of rain here) is washing the topsoil from the forest down into a creek and then right out into the nearby river. In a recent rainstorm we got 4 inches in two days and lost an inch of soil from the path we had cleared as a hiking trail.

I'm wondering what to do about the missing understory and bare soil between trees. There are some small plants, just not enough to hold soil in place. The trees are mostly maples, hickories and other similar nut trees, and oaks. I was thinking of maybe trying some English understory plants like bluebells because they have adapted to living with earthworms, but hesitate to introduce another alien species.

Also, how are people finding the presence of earthworms affects permaculture mainstays like mulching under trees? When I lived near Philadelphia, our worms were so active there was nothing left on the soil surface after a few months except hardwood mulch, and even that would get digested after a few years. I'd rather not spend the money and fossil fuels to keep buying and spreading hardwood mulch, now that I have so much more land, and it doesn't seem sustainable to me to shred wood to use as mulch.

Best way to find out surely would be to dig a few test holes to see what's down there. When you say invasive earthworms you mean one of the species of earthworm that aren't indigenous to our country yes?

Can you coppice some of the trees for woody mulch? It doesn't need to be chipped, just cut in short sections. Maybe plant some trees or shrubs specifically for this purpose in the future.

Yes, earthworms aren't native to the forests of the Northeastern USA. Coppicing is a good idea. And right now there is a lot of dead wood we can cut.

We can't see what you are seeing, but do you think that the forest canopy is so dense that light can't filter in and nourish the understory in a satisfactory manner? Sounds like the forest has matured to a point, it's smothering itself. Could you open it up a bit more? Also, I could see some hedge laying (plashing) could be helpful to slow and hold back the water runoff and soil erosion, this by itself could let more sunlight in...

Maybe the forest floor needs more light. Maybe they are to blame. Have you tried transplanting some trees yourself. Maybe some critter is eating/moving all the seeds.

Is there something that you can spread around to take the place of the leaf mold etc that is still beneficial but that the worms won't eat? Don't have any answers just lots of questions

Earthworms are not indigenous to the North American continent at all. They are an invasive species introduced in the Colonial era via the ballast of docking ships from Europe.

Their presence in the soil dramatically altered the nutrient cycle in most forests, primarily by altering the quantity and nature of the composting biomass on the forest floor.

There's a very detailed and interconnected explanation of this in Charles C. Mann's most recent book, 1493 (which is an excellent read for general mind-blowing on a variety of topics regarding ecological and social evolution)

I'm pretty sure it's not too dense, since there are lots of patches of sunlight that get through to the floor in summer, and a lot of the trees are dying out (like 1/7). I saw this same thing in forests in PA, in the middle of summer the forest floor was bare dirt instead of leaf mould, and there weren't many plants between the trees. They blamed it on deer overgrazing, which was also a problem, but I think the problem wasn't as simple as just an overpopulation of deer. I've seen forests in Indiana where there was leaf mould, and you could see all kinds of wild ferns, columbine, etc. in the forest. They say worms only travel about 5 meters a year but if they get carried in water runoff then it's got to be a lot faster.

Half of our forest has the invasive bush honeysuckle as the only understory. I'm hoping I can just slash all of those out and lay them around to conserve moisture under the trees, but am a little fearful they can root and grow if I don't burn them.

Since you can't get rid of earthworms once they're here, it looks like we'll have to rethink what a "natural" forest is for Eastern North America.

I am very sorry to hear of such a problem and i wish i knew more to help. I agree with you on all you said, introducing outside species might help short term but turn into kudzu (an asian weed taking over georgia). I had hoped to find a link from the state of ky but all soil erosion links by the state are telling how to farm such slopes....surprise me for sure. I do suggest you call the state, I would start with the department of agriculture, to find local suggestions. Also the land universities generally have things to say on this subject.

For now, slowing down the water as it goes down the slope is all i can suggest, sounds like yu have logs around so position them cross slope. Make your path winding not straight up and down the slope. Yes mulch would help a ton too, I hope the state can tell you good plants for your area. Perhaps you can drop soome branches cross slope....not a great reason for trimming a tree but if the trees could speak i think they would sacrifice limbs to save their soil.

There is a bright spot i can see, sounds like your woods are perfect for ginseng growing. A profitable crop which would hold your soil in place....havested only after a long time so no need to think of it causing more erosion.

I went to lay down and I couldnt sleep until i said...if i recall those worms only live in the upper soil unless they are escaping cold. If I am correct in this you might gain much control by putting chickens there to eat them. Just a thought.

I found this site with a lot of good information about the bush honeysuckle, at least! They say if you cut the bush then immediately brush on Round-Up (I know, hate to support Monsanto!) it will prevent it from re-sprouting. They also offer understory plant choices that are native to the area. http://mdc.mo.gov/sites/default/files/resources/2011/08/cursebushhoneysuckle_2011.pdf

I brought up the erosion problem with the fellow I bought the house from. He used to work in Kansas in parks and said they put down dead branches horizontal to the flow of water to slow it and stop erosion. I've started doing that. I guess they can catch leaves and twigs to form small dams and slow the flow. Not unlike what some of you have said.

I'm wondering if running pigs through the woods in summer would help - they'd dig and eat the worms, apply fertilizer, and get fat on fallen nuts. Their ruts they dig would hold water so it could soak in. Biggest problem is fencing them in with so many roots and rocks in the ground. With over 20 acres of woods, tho, I don't know if my few pigs would make a dent in the problem. I guess I could try a test paddock. Biggest problem is the woods is very far from water sources, but at least it's downhill from the pond. Just really far to string hose.

http://threatsummary.forestthreats.org/browse.cfm?stateSearch=KY

http://www.invasivespeciesinfo.gov/unitedstates/ky.shtml#.UQAPU4aPtGO

There is some resources for you....for the honeysuckle that is. I woke up googling and I have gotten much information on invasive species and I think your problem is not worms, they are northern to you in areas scraped of dirt during the ice ages. This leaves that erosion is taking away your understory. The honeysuckle is likely your problem, the links above are government on this issue.

I think animals might easily cause erosion by digging. Others would be mre helpful when it comes to what will help, repost in animal forums imo. I think trees are simply living fence posts aren't they

i still hope yu will plant some ginseng ...it totally belongs on that hill some place.

I'll look into growing ginseng. What I've heard is it's really expensive to get the plants and they often just die because they need a healthy community of plants and fungi to thrive. That article on how to get rid of the bush honeysuckle listed other shrubs to grow in its place and several of them were things I've always admired but never grown (like witch hazel). I think that will be next year's project, but maybe over the summer I'll start transplanting seedlings and looking for seeds.

i imagine if yu spend money on seedlings you will be very much invested in them actually growing and on a hillside which presently seems to be slipping down hill. You may want to look into buying stratified seeds (apparantly the seeds like to hang out for 12 months before growing and the seed people do that for you) that isnt terribly expensive.

It does take forever before you can harvest it though...deep roots would hold that hillside in place. Hopefully if you plant some they will spread on their own, or you can harvest the seeds yourself which would keep more for you.

I am sure there is dozens of lovely things to grow on that hillside.

would try honey berries, and other fruiting berrys.

I would also plant some mints and a hardy thyme (fuzzy) up high, and see if they will take. They are very resistant to nibblers.

look at food forest mushroom cultivation on standing wood, some folks doing it commercially a little further south.

see if you can bring in quail or other ground birds, a lot of states are encouraging it now.

if you make slash piles for cover, you can usually keep ground birds around. will bring more foxes tho.


How many voles holes are there?
If you had that many worms, would expect a ton of moles and voles around too.

It is very odd to hear you describe a bare soil under a standing forest, even a fairly sparse one. Where is the leaf-mulch going? Some months and years of observation may solve this. Everywhere I've lived, I've used the forest as a source for mulch, not a sink for it!! Is the site sloping enough that heavy rains and wind are simply carrying the mulch away? Are there spots lower down where it is accumulating (perhaps for use?) The idea of laying logs and brush on contour to hinder this process is a good one. Until the erosion problem is resolved, I wouldn't get rid of any invasives....any plant is better than no plant. Coppice them and mulch the tops, and let the stumps sprout again for more coppice.
I wonder if it could be that the original understory plants and ephemerals were eradicated at some point, perhaps by an episode of logging, grazing, or farming, and simply haven't found their way back yet. You might try reintroducing some of these, preferably by scattering seed gathered for free somewhere, so that your investment and disappointment won't be so much if they fail. In particular, get things like bloodroot, trilliums, hepatica, trout lily, and such like thriving before you try ginseng!
If you are on site and game for some active management, you could try introducing some fairly aggressive groundcovers into the worst eroding sites. Periwinkle and English ivy come first to mind. But bear in mind that while these will trap soil and mulch and prevent erosion, they will be the only things growing there for the long term unless you come back and eradicate them later.

I think I'll pass on the ivy and vinca, they are invasive! The bush honeysuckle is allelopathic, so nothing can grow if it is there. I'll start looking for seeds for trout lily, blood root, etc. That sounds good. Maybe lots of seeds are there, waiting for the bush honeysuckle to go away so they can grow.

Deer eat leaves some, but in the forest in our yard in PA there were NO leaves left on the ground by mid-summer. Lots of those big fat worms that almost look like snakes, tho. We did have vole problems, but foxes eat voles, as do hawks and owls, which we had plenty of. Here there was a bad drought during the summer so maybe the leaves were gone just from deer and the understory is missing just because of the bush honeysuckle. I hope.

Another thing you might try is to lay out some contours and put in some narrow deep swales. You might have to leave gaps for the trees, and leave the larger roots crossing them, somehow. The goal is to trap runoff. Logs on contour with earth packed behind them might work almost as well, and be a lot easier. If you can improve moisture retention on site, you will improve drought resistance. The trees will grow more leaves which means more mulch, and the berms will catch the mulch. And because the whole system will be less moisture stressed, more plants can get a foothold, including the desired understory. Deer exclusion might be a tipping point too.....in many areas deer are overpopulated due to elimination of predators, proliferation of ideal thicket and regen habitat, and critical opinion of hunting. Baited electric fence is the easiest solution.
On the short term, try to be sure no organic matter and topsoil is leaving the site through erosion. Throw cut brush into any gullies or spots where water is flowing, or better yet make woven-brush and stake barriers.... The easy way to see this is to get out on the site in a hard rain and observe. (PDC students who think to do this during a course get brownie points!). Begin the work at the top of the slopes where water starts to run and gather and work your way downslope....

Thank you so much, very helpful!

I ran over to this forum and looked for this post when i heard about the free tickets to sepp. If you are on the mailing list you likely have heard about that already.

What I think is most interesting (for me anyways) is that he will be answering posts on another forum, under homesteading the earthworks forums. May I suggest you repost this problem on that forum and get expert opinion if possible. .

I would love to read his reply to this problem as well soy yu would be doing more than yourself a favor

I'd recommend terracing and building swales. The swales will keep the water and soil in place as will the terraces. If it's deer, I'd increase the edible bushes and if it's worms, where are all the birds? Maybe, you can improve the bird habitat by putting in more nesting areas and wildflowers - that will bring down the earthworm population.

When I look at the forests around here, leaf litter covers the ground. Glaciers didn't cover my farm during the last ice age, therefore, earthworms have lived here continuously for millions of years. Seems to me like the introduced earthworms perform the same ecosystem services as the native worms.

The ice-sheets didn't cover the area from Philadelphia to Washington DC, therefore immense earthworm biodiversity exists in those areas. I watch robins carrying earthworms hundreds of feet in a few seconds, and inadvertently drop them. I watch deer step in damp soil, and drag that soil for thousands of feet in a jiffy, no doubt carrying earthworm eggs with them. So I think that northward migration of worms happened quickly after the ice receded.

I consider biology as fuzzy and indistinct. Earthworm taxonomy seems much more ill-defined than that. A special case of extreme chaos associated with identifying which species or even genus we observe. Therefore, I don't worry about earthworms.

Joseph Lofthouse wrote:When I look at the forests around here, leaf litter covers the ground. Glaciers didn't cover my farm during the last ice age, therefore, earthworms have lived here continuously for millions of years. Seems to me like the introduced earthworms perform the same ecosystem services as the native worms.

The ice-sheets didn't cover the area from Philadelphia to Washington DC, therefore immense earthworm biodiversity exists in those areas. I watch robins carrying earthworms hundreds of feet in a few seconds, and inadvertently drop them. I watch deer step in damp soil, and drag that soil for thousands of feet in a jiffy, no doubt carrying earthworm eggs with them. So I think that northward migration of worms happened quickly after the ice receded.

I consider biology as fuzzy and indistinct. Earthworm taxonomy seems much more ill-defined than that. A special case of extreme chaos associated with identifying which species or even genus we observe. Therefore, I don't worry about earthworms.

Just a brief note to second what Joseph said, here.

Where I live, in the northern Great Lakes area, there are numerous species which are considered "invasive", but a few hundred miles to the south (Ohio, Indiana or southern Wisconsin), these very same species are considered "native".  Among these are species like black locust (on the ragged edge of the natural range here, currently), phragmites (not quite here, yet, at least by natural spread, but it won't be too long), and - yes - earthworms.  It is difficult for me to conceive that these species (and many more) weren't here, temporally variable local climate dependent, during the previous interglacial period.  A couple of miles of ice thickness, parked over the land for a few thousand years, is very likely to markedly decrease the number of "native" species, whether higher animals and angiosperms, or algae and phytoplankton.  When the ice retreats, stuff begins moving into the newly exposed territory, all of it ipso facto "invasive".  To me, it seems a bit prejudicial to get a case of the vapors over earthworms, just because they can't move as quickly as caribou or can't tolerate permafrost, so it takes them a while longer to move into the newly exposed territory.

Anyone interested in the succession of ecosystems during and after deglaciation might find E. C. Pielou's "After the Ice Age" an engaging read.  This is a bit dated, now (copyright 1991 - she presents the "ice free corridor" as fact, and it's at the moment at least considered disputable as to existence and extent, as best I can tell; rightly or wrongly, she presents orbital mechanics as the principle driver of climatic variation - i.e. Milankovitch cycles), and no doubt there is more recent scholarship available on this topic with regard to the fundamental data on which her arguments are based.  However, she does present scads of data - from grasses, flowering plants and tree pollens to invertebrates, fishes and mammals - demonstrating how the margins of retreating ice sheets passed from lakes to grasslands to savannas to forests, both coniferous and deciduous. She also isn't shy about discussing the uncertainties in this indirect data (how far can the wind blow pollen of a coniferous tree, versus a deciduous tree, before it lands in a pond and is subsequently deposited in mud?  how tall are the trees?  how strong is the wind? what is the prevailing wind direction during inflorescence? etc. etc.).  Her presentation certainly helps to make sense of much of my local and regional landscape - everything from the mixture of northern hardwoods and boreal forest - small pockets of boreal within the hardwoods, mostly - to glacial striations on prominent balds, to Brobdingnagian katabatic sand dunes (some of which swallowed up standing forests), to kettle pot inland lakes.  Not that you can't find this information elsewhere, but it's nicely packaged up, all in one place, in this book.

Whatever the case, this book is worth a read if you can find a copy.  Mine came from Goodwill (a resale/charity store) a few years ago, after a biology or ecology professor had retired from the local university or was otherwise impelled to dispose of a personal library.  This book doesn't have the "ex libris" in it, but some of the others I picked up at the time in the same bunch, do.  Somehow, I always appreciate a book more when I know that someone smart, thoughtful and maybe even just a bit wise owned it before me.

And back to the original topic, I am not at all worried about "invasive" earthworms, at least of the sort we have around here.  Introduced from New Guinea and a dozen feet long, maybe, but not the ones we've got.

To me, blame only seems applicable to those with free will. I am not sure people have free will. On the other hand, I guess I can’t rule out the possibility that worms do have some form of it. Regardless, we cannot kill the worms without killing many other species, so I would throw biodiversity at the problem and let evolution take its course.

S Bengi wrote:Maybe the forest floor needs more light. Maybe they are to blame. Have you tried transplanting some trees yourself. Maybe some critter is eating/moving all the seeds.

To me, this is the reason that the understory is affected rather than earthworms. Plant more shrubs and bushes like berry plants on the edges of that problem area.  Area that get sunlight.  This too will help with the erosion problem.

There are areas in Northern Canada where earthworms were introduced by fishermen. Thus humans effectively "sped up"  succession significantly faster for this one creature, beyond where plants and particularly trees, were able to adapt.

I've been told that many of the earthworms in Canada were brought by humans from Europe.

I've also read that there's a newly imported Asian worm (jumping worm maybe?) that is a problem in areas of the USA.

So it seems as always when Nature and Humans interact, things are "complicated". I just hope Nature is resilient enough to rise to the challenges.

Jay Angler wrote:There are areas in Northern Canada where earthworms were introduced by fishermen. Thus humans effectively "sped up"  succession significantly faster for this one creature, beyond where plants and particularly trees, were able to adapt.

I've been told that many of the earthworms in Canada were brought by humans from Europe.

I've also read that there's a newly imported Asian worm (jumping worm maybe?) that is a problem in areas of the USA.

So it seems as always when Nature and Humans interact, things are "complicated". I just hope Nature is resilient enough to rise to the challenges.

I didn't mean to imply that I think there are no invasive species.  Currently, local to me, we have a minor infestation of Japanese knotweed which is deep rooted and can spread rhizomally.  It was introduced as an ornamental, and has now spread to many places beyond the initial plantings - road and trail sides, edges of wooded copses and thickets, margins of clearings, and so forth.  On the other hand, my brother's goats seem to love the stuff!  It is an ill wind indeed...

I can't speak for the challenges of the Canadian North in regard to earthworms (vis-a-vis the US), though I do know there are strict prohibitions against bringing live bait of any sort into Canada across the border from the US (even leeches, when canoeing across one of the border lakes in the Boundary Waters/Quetico area!).  It would not surprise me that fisherfolk have "helped" earthworms in their territorial expansion northward.  But, down here in the Lower 48, earthworms are either native, or, if not native, at least are now fully naturalized (there was some discussion up thread to earthworms being introduced by Europeans - and I haven't yet chased down the reference in 1493 - but I'd be surprised to learn that there truly were no annelids in North America prior to the arrival of European ship ballast).  However, there are plenty of healthy forests replete with earthworms, so I don't think earthworms are the culprit in the OP's stated problem.


And as a follow-on to my reference above to E. C Pielou's "After the ice Age" (subtitled "The Return of Life to Glaciated North America"), here a quote from the first chapter (starting on page 7, then jumping over some maps of ice extent to page 12) which lays out the scope of the book:

"As the ice sheets vanished, they left a growing expanse of bare ground where, at first, nothing lived.  Over the millennia, the area has been colonized by an enormous number of plants and animals whose permanent home is in the low-latitude regions that are ice free during the glaciations.  The invaders managed to occupy the newly exposed land and water as it became available, and now they form the biosphere of most of northern North America.

Where they came from and how they got there are the topics of this book."

Wood chips are usually free from tree service places. And chickens are very good at spreading piles of wood chips around and they eat worms. There is a technique that involves sound to force worms to the surface, if you had chickens and did this you can feed them for free, get rid of some worms, and get wood chips spread.

I have always thought that earthworms were beneficial to the soil.

There are good species and there are bad ones.

Good earthworms are red wigglers and night crawlers that we buy for soil health.

These earthworms improve soil health through aeration, increase nutrient availability, and aid in decomposition of organic matter.