What I have observed in nature is somewhat opposite of this. Specifically in north Louisiana, healthy pines typically have natural mulch mounds several inches thick right against the trunk tapering off with distance from the trunk. This natural mulch is the tree's own bark (flaking off from trunk) and its shed needles. Of course the build-up is over-time (years), but nonetheless it would seem prudent when planting trees to go ahead and extend at least an even layer of mulch all the way to the trunk (say 1/2-1" thick).
A thin mulch layer like this shouldn't harm the tree or prevent it from breathing, and should help it as far as soil temperature, moisture retention, etc.

Any thoughts on this?
Has anyone tried different methods and if so were there any quantifiable results?

Has anyone tried different methods and if so were there any quantifiable results?

My wife and I train dozens of volunteers a year on how to plant trees on her projects. What we say is that think of what your skin looks like after you've had a wet band-aid on your finger for a few days.

That is: mulch on a trunk in monoculture turf with predators excluded: superduper bad.

Mulch on a trunk in regularly irrigated managed landscape: super bad.

Natural flaking bark in healthy ecosystems at a much lower density/cm³ and with a much higher airflow: still harbors critters, but there are other critters out there that are hungry and turn the mulch looking for snackies.

Our managed and industrial ecologies are much different than "natural" landscapes, which is why the mulch we choose on our landscapes is different than in nature.

but are you going to be buying tree specific mulch for all your specific trees???

on my sand .. read that: ultimate and total drainage ... i put mulch right up to the tree ... perhaps one inch back on tiny things ... [my beds get 4 to 6 inches of chipped wood.. settling to 3 to 4 ... but down to an inch near a specimen]...

because the water retention of the soil is much more important.. that any potential bark damage ... especially on a recent transplant ....

but when we are using the word 'volcano' ... we arent really discussing a little surface coverage of mulch ...

scot.. you know well enough ALL THE VARIABLES.. to deal with it.. as do most of us .. dont get caught up in the extreme examples.. and confuse yourself ...

the only problem is the peeps who figure that if one inch is good ... well 24 inches.. is 24 times as good.. so the default answer to those who think that way is.. leave it bare ... [they also think that if a handful of fert is good.. then the whole bag must be great.. lol] ....

as i alluded.. soil type is probably the defining variable ...

i recall one storm.. when i had spots of 6 inches of standing water in low spots .... it was gone .. SOAKED in within the hour ... and i swear you could have driven a cement truck over it the next day ... i would bet.. within 2 days.. it was august.. the mulch was basically dry ... [i do recall.. having to go out there.. and move piles of mulch that floated around ... back to where it came from ... lol]

now turn that around on clay soil.. and perhaps that mulch could stay too moist.. on the trunk.. for months on end ...

err on the side of less or none.. but i wouldnt lose sleep over a dusting at or near the trunk ... its the volcano thats the issue ...

ken

Like Ken said, don't try and use an extreme example-mulch volcanos-to justify a much more moderate situation of a little itty-bitty mulch material up against the root flare area.

+oM

Some assumptions here:

1.) That commercially applied mulch functions just as a natural mix of pine straw with some bark in it.

2.) That mulch piled in the short term functions for the tree as does mulch that built up over years.

3.) That conditions one type of tree (pine, perhaps one or a few species, in one type of soil in one area of the country) are advantageous for all trees everywhere.

Not trying to distort your post, just point out some of the unproven potential failure points in the theory.

It would be interesting to know how pine needle mulch raked up in a forest would compare to shredded bark mulch purchased at a hardware store or Wa-mart, for common landscape trees like oak & maple.

Richard.

Just my thoughts. Probably off...

John

1., 2., 3..

Maybe I should clarify. I want to see scientific evidence. In other words, a scientific study published in a peer review article with specific diseases studied. Anyone can put out extension articles stating things that aren't scientifically valid. These articles make the same general assertions as what has been said on here, no actual data to support the claims. By the way, I have a PhD in forest pathology and work as a professor at a major University, so I've given this serious thought with years of experience. I don't at all believe too much mulch is harmless, I just have different reasons.

I checked my 2nd Ed. of Harris, Clark and Metheney, but it isn't specifically mentioned. However, I used to work with Dick Harris and he said don't do it. That's good enough for me and my wife (who studied under him as well). I might know an old-timer who doesn't have a problem with a mulch volcano, but I can't name one.

Edit: that symbol was supposed to be a "does not equal" symbol

Our open grown pines also mound up like that here, as do junipers and some other species with open grown specimens. I would also think a slow accumulation of material next to the trunk is not as traumatic to the trunk as a sudden pile of mulch inches thick placed in the area.

Do open grown trees or trees that are mowed around show this heaving near the trunk more than forest trees? It would make sense that lawnmowers could disturb this process a foot or two away from the trunk by further shredding the bark/needles into very fine bits while also shooting the pieces into the air and away from the spot they fell.

John

Edit: To tie in the last paragraph with the point I was trying to make. I have dug up several saplings in the understory of the woods behind my house. I surprisingly found in all cases that the actual root flare was several inches below the top of the decaying matter layer on top of the soil. I infer that the seeds germinated at a certain level and then were buried with many years of leaves/stick/bark that take time to decay. This is a very porous layer like what you describe in your picture and can be compressed to an inch or so if it is wet and pressure (from my foot) is applied. So, in a forest that mounding up of pine needles and bark would extend beyond a couple of feet actually continuing out to the forest margin.

Note that this occurs on large trees, not ones small enough to be transplanted. Don't think I have seen any from 3-4" diameter on down with mounds of mulch like this against them in the woods. But I do see the light layers of mulch at trunks of these smaller size trees, prompting me to question the wisdom of pulling the mulch away from the trunk. My assertion here is that if you have a 1/2 - 1 1/2" layer of mulch perhaps one should go ahead and place it agains the trunk. That seems to match what I'm observing in nature. That shouldn't be so thick as to smother the tree, etc. And it would help cool root system at trunk (some shading from direct sun) and maintain moisture slightly better.