Invaders!!

Most reports make the claim that earthworms cause major abiotic and biotic soil changes, said with a negative implication. Well, they do make changes, yet negative is not what I would call them.
https://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/soils/health/biology/?cid=nrcs142p2_053863
Having no leaf litter layer is a major problem. It does not, however, change the rest of the story.
"Earthworms dramatically alter soil structure, water movement, nutrient dynamics, and plant growth. They are not essential to all healthy soil systems, but their presence is usually an indicator of a healthy system. Earthworms perform several beneficial functions.

Stimulate microbial activity. Although earthworms derive their nutrition from microorganisms, many more microorganisms are present in their feces or casts than in the organic matter that they consume. As organic matter passes through their intestines, it is fragmented and inoculated with microorganisms. Increased microbial activity facilitates the cycling of nutrients from organic matter and their conversion into forms readily taken up by plants.

Mix and aggregate soil. As they consume organic matter and mineral particles, earthworms excrete wastes in the form of casts, a type of soil aggregate. Charles Darwin calculated that earthworms can move large amounts of soil from the lower strata to the surface and also carry organic matter down into deeper soil layers. A large proportion of soil passes through the guts of earthworms, and they can turn over the top six inches (15 cm) of soil in ten to twenty years.

Increase infiltration. Earthworms enhance porosity as they move through the soil. Some species make permanent burrows deep into the soil. These burrows can persist long after the inhabitant has died, and can be a major conduit for soil drainage, particularly under heavy rainfall. At the same time, the burrows minimize surface water erosion. The horizontal burrowing of other species in the top several inches of soil increases overall porosity and drainage.

Improve water-holding capacity. By fragmenting organic matter, and increasing soil porosity and aggregation, earthworms can significantly increase the water-holding capacity of soils.

Provide channels for root growth. The channels made by deep-burrowing earthworms are lined with readily available nutrients and make it easier for roots to penetrate deep into the soil.

Bury and shred plant residue. Plant and crop residue are gradually buried by cast material deposited on the surface and as earthworms pull surface residue into their burrows."
 
Those were my points to the benefits of the worm dudes as well. I've personally seen the benefits to soil structure a year after installing large beds with mixed types of OM in previously compacted soil. No Air Spading, just a thick layer of OM over killed turf.

Tom's points about the erosion due to lack of leaf and whatnot debris I vaguely recall reading. It doesn't sound like there is any reasonable solution however.
 
2 thoughts on the last 2 posts about worms:
1) interesting that the one paper recommended eradication efforts. I heard Fisk with my own 2 ears earlier this week saw that is nor feasible. I'm not questioning what is written...just pointing out that at some point it seems she may have changed course. She did talk about not spreading soil between woodlands on equipment though...that seems like a relatively reasonable effort.
2) I think the NRCS info refers more to agricultural soils (or in other disturbed soils as JD alludes to) that are depleted, compacted, and otherwise heavily disturbed compared to forest soils. Fisk talked about how it is difficult to get people to understand that what is good for soil in the field is not necessarily good in the forest.

On worms: whatever they do or don't do, I think they are drasti5 different than other invasive for 2 reasons:
1) while there is indication they may cause harm, that seems to be relatively minimal.
2) control once they are established in a stand just isn't going to happen.

I wonder if an overentheuiastic reaction to worms causes too much negative pushback for other invaders that are bigger problems and can be comtrolled?
 
@ATH

I agree. That's what the response was many years ago when this research broke. The guffaws and cat calls and Chicken Little reactions were loud

My takeaway was a hopeless awareness of another environmental degradation. Where is the social indignation about worms!? Fishbait is a problem!? Ugottabekiddin!

No budget for the environment...I'll stop there or I'm likely to go political



I wonder if an overentheuiastic reaction to worms causes too much negative pushback for other invaders that are bigger problems and can be controlled
 
ATH said:
... Fisk talked about how it is difficult to get people to understand that what is good for soil in the field is not necessarily good in the forest...
Click to expand...
For a very good reason, it is not true for the majority of forests worldwide. Earthworms have been moved around so much in Europe that determining their native range, exactly, is not possible. What we do know is that most forested areas here and elsewhere, do have earthworms and the degradation attributed to them by the anti-worm movement is not manifested in them. Quite the opposite, in fact, massive diversity and increased stability.
 
Yes...there were earthworms here before the "invasives" showed up. However, the non-native worms munch things up much more aggressively. European ecosystems are vastly different than America's - for many reasons, perhaps one of those reasons is the worms. That is the whole "point" of discussing invasive species - when you introduce a species into an ecosystem it has not interacted with before, then things can change rapidly.

As I outlined earlier, whether that change is negative or not, is largely dictated by perception and management objectives.

My personal opinion is there are some invasive species that (A) cause significant degradation that (B) can be managed with a reasonable budget and effort (Honeysuckle is the most pervasive in my immediate area. Ailanthus in SE Ohio, Buckthorn in NE Ohio, etc...).

For those non-native species that don't fit those two criteria...lets gather information, but not get too excited about them. Worms don't meet MY threshold for (A) and probably very few people's criteria for (B). But just to clarify, the DON'T increase diversity or soil stability in the hardwood forests of America. I don't think that puts me it he anti-worm crowd...just it is what it is.

By no means am I "anti non-native". My argument is that we do not live in a "native" ecosystem any longer, so we need to find the species that are going to provide the most benefit and least harm and move forward from there. (again, recognizing 'benefit' and 'harm' can be hard to define)
 
ATH said:
... My argument is that we do not live in a "native" ecosystem any longer, so we need to find the species that are going to provide the most benefit and least harm and move forward from there. (again, recognizing 'benefit' and 'harm' can be hard to define)
Click to expand...
I couldn't agree more. One of the things I enjoy most about being an arborist is that, if allowed to, we can mix and match each microsystem that is in our charge for maximum health, beauty, and longevity. It is always a challenge because it is always different.
If one pill worked for everything, there would be only one pill.
 
There was an interesting comment made in a June 17, 2013, Northern Woodlands magazine. The author quoted Tim Fahey from Cornell University as saying that in his study area the invading worms aren't really invading anymore and that barring a big change they are pretty much where they are going to be.
Another comment by the author was that on a tree walk an area "infested" with non-native worms they found a rich assortment of herbs.
"I went for a worm walk with Fahey and a conservation group in eastern New York, and we found earthworms in an ecosystem that supported a good diversity of trilliums, wild ginger, jack-in-the-pulpit, and other native forest herbs. If we hadn’t doused the ground with mustard-laced water, an act that prompted the worms to race to the surface, we might not have even known they were there."
 
Years ago before the criteria for 'invasive species' was agreed upon I was at a planning meeting for the Minnesota Shade Tree Short Course. There is always a rough theme for the conference. Someone suggested 'invasives' which lead to some productive discussion as well as the usual snarkiness :)

Someone asked for a definition and examples

Examples given:

Turf grass
Russian olive
Amur maple...in certain counties
Colorado blue spruce

I added...skid steers and developers

The definition of invasives is pretty well worked out now. That's another discussion.
 
In the PNW barred owls are invading and throwing off the balance. Interesting enough they are hybridizing with spotted owls.
I’ve recently read where there use to be a distinct population subspecie of raven in Northern California however with hybridization the specie was asorbed.
https://sora.unm.edu/sites/default/files/journals/auk/v111n02/p0487-p0492.pdf
Love to go more in-depth but my brother in law imported a plague into our house from Thailand, two sick kids and a sick wife. I hear the sick bell ringing..
 
Interesting and all...but is that a problem?

The problem when a species goes extinct or a new species invades is that it upsets the "natural balance"*. So spotted owls are going extinct which would leave a gap in the food chain or such. Barred owls move in and fill that gap. Is their behavior or feeding drastically different? (I don't know - maybe it is???) If they feed on different species or in significantly different quantities, that could cause an imbalance. But if they fill the same niche in the ecosystem, I'd ask "what's the problem?"


*"Natural balance" is a whole different conversation we really haven't hit too hard in this thread yet... To define that, you need to pick a moment in time and call that "ideal" or some such. The nature of nature is that the only constant is constant change. The big difference we are covering here is speed, and possibly direction of that change. Goes back to: is that good or bad?....which is user defined.
 
ATH said:
difference we are covering here is speed, and possibly direction of that change.
Click to expand...
And there it is. To us, these invaders are changing things in the blink of an eye which is quite different than the changes that occured in the past on a geological time scale. While globalization has greatly sped up the process, introduction of alien species really began when seafaring peoples really got moving around and brought things with them or took them back home on the return.

The rest is history as they say.
 
JD3000 said:
And there it is. To us, these invaders are changing things in the blink of an eye which is quite different than the changes that occured in the past on a geological time scale. While globalization has greatly sped up the process, introduction of alien species really began when seafaring peoples really got moving around and brought things with them or took them back home on the return.

The rest is history as they say.
Click to expand...
I agree, while there has been cataclysmic events throughout life on this planet we are in the early stages of unknown changes.
I brought up the spotted owls for example. They are under assault on many fronts, loss of the last of the old growth, and now being out competed/bred to extinction. I believe it's futile to try to save their population, but I rather be on the side of trying, the alternative doesn't sit well. The migration of Barred Owls doesn't have to out compete, displace, or fill the Spotted's niche. With the fragmented old growth islands all it will take is time, hybrids will dilute the distinct Spotted owls to the point where there will be a slight relic marker on the Barred owls DNA of the hint of what once was.
The tighter you try to hold a handful of sand the faster it runs through your fingers, but perhaps we can buy some time for the "native" species to adapt to these new pressures. I often trip on timescales, in my backyard there is geological evidence that the northern PNW old growth forests are only a few generations in. The entire Puget Sound region was buried under an estimated mile thick ice sheet (locally greater) peaking 11,000 years ago. No one talks about how long it took that ice to fully recede... Now consider that that some of the oldest trees in the PNW old growth live will into the 1000 year mark. These forests are only a dozen or so generations in. Personally I find that amazing, it's taking tree time into a new level.
It's not uncommon to come across palm leaf imprints on glacial erratics, compressed peat (from about 100,000) years ago), mammoth parts, and other treasures on our beaches eroding out of the bluffs.
The sad thing is that in my minuscule life time I've witnessed so much change I question how relevant my experiences will be to my children. Pacific madrone is in decline, a unknown factor is worth of study on Bigleaf Maple, Garry Oak is nearly done, Cherries are getting hit HARD, Laminated Root Rot is exasperated for unknown reasons (current research looking into climate change), the point is there are so many assault fronts. This is not a glacier, climate, invasives, Eurocentric human pressures, it's all of it.
So I rather pull up Scotch Broom, and Holly seedlings when I go for hikes in the last largest continuous PNW rainforest in the lower 48.
Don't get me started on fire prevention...
 
Since we headed here ... I think the worms might be a case of hysteresis. An "invasive" (last use of quotes, I promise) moves in and finds a hospitable environment. Very often this hospitable environment has been caused by some external, often undetected change. More acidic rain, higher local temperatures, more human activity of some sort, ect. The native stuff is on the downfall, or is more vulnerable for some reason. We like to blame it on things being "intorduced" but is likely very much more complex than that.

Then the invasive things get going. For a time it is like a party, and we all see the changes. Changes we can all see and point at are the kind that gets talked about. Especially fast ones. But resources are still limited. Like in the case of the worms, if all the leaf litter is gone the stored food is now gone. Their population will fall if it previously boomed. After a few boom and decline cycles things settle in. The changes are permanent, but maybe not as overwhelming and continual as first expected.

So assuming we accept that we can't go back ... and we can't. I think we need to be very careful about what point in these natural cycles we decide on a response, and what we think the outcome will be.
 
Levi.CO said:
Thanks Tom and ATH for the old growth links. Some pretty stuff there, amazing how small the patches are.
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I'll use Ohio as the example because that is where I am. Quick history points:
-Antiquities Act passed 1906. If it wasn't protected by a private owner before the...it wasn't protected.
-Woodlands were thought of as wild and the land needed to be freed from these burdens to be allowed to be fruitful.
-Iron furnaces used something like 3-400 acres per year per furnace to make charcoal. I think there were 9 big ones in southern Ohio at the peak. (correction...46 furnaces)
-Homestead Act required land to be developed
-Very productive soils in NW Ohio.

Probably nothing earth shattering...but a combination that left little reason to leave big timber.
 
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