mulch for trees

Hopefully somebody in this newsgroup is knowledgeable in this area.
Isn't it true, that there is little value in piling mulch around the base of large, established trees. I understand the practice when a tree is much smaller and newly planted.
I appreciate that some people like the aesthetics of placing mulch around their trees, but if the tree is 8-inches in diameter it is likely that the root structure is so widespread that a pile of mulch around its base provides little benefit.
True of False?
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David Emerling - Memphis, TN
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On Sat, 22 Nov 2003 18:09:18 GMT, "David Emerling"

Mulching keeps the ground moist, helps prevent damage to the trunk (keeps string trimmers and mowers away), and provides some nutrition. A 2 or 3 inch layer is enough, but it's a waste to make "volcanoes." Piling soil or mulch against the bark can harm the tree. I just completed deciduouss tree fertilization using tree spikes along the drip-line circle of the trees.
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True. Countless trees die when people pile mulch up under the base. Never cover the flare of a tree and mulch is best served at the drip line which is where the fibrous roots are, not at the base where the tree has anchor roots (which rot when mulched too heavily and close to the flare).
On Sat, 22 Nov 2003 18:09:18 GMT, "David Emerling"

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I might be wrong, but I think one of the purposes of mulching is to discourage other plants from taking root close to the tree and providing competion for water and nutrients. In dense forests, where some of our landscape trees are native, trees generally "take claim" to the land under their canopy, and between the smothering effect of a thick layer of dropping leaves every fall and the general drought-like effect that a dense canopy provides to the soil under it, few plants survive to compete with the trees. In an urban landscape, people often want lawns to grow under trees, or in some cases, perennial beds or shrubberies. Mulch probably would benefit the tree by reducing the competion, but that runs in direct contradiction to the landscaping efforts that people are making. I think it's a nice, satisfying (and more natural) look to see a medium large tree surrounded by a large circle of mulch or grass-less area (like 20 feet in diameter) , but for people with small urban lots, it's probably only going to happen rarely - because of all those fun flowers to grow, or because they think the neighbors want to look out on lawns.

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Hi greg, The kind of mulch I use from my mulch pile (leaves, grass, etc.) does not discourage growth of weeds or encroachment of the lawn. However, it's other benefits outweigh this disadvantage. Another way to ease the problem is to mix a lot of sand near the edges of the circle to make the removal of encroaching grass easier to pull out. I don't think wood chips are a good solution because they tend to distribute themselves all over the lawn, and they take a long time to break down. Home lawns, unlike forests do not have trees tightly packed together, so weeds can get plenty of light to grow. I have multiple dwarf fruit trees spaced to a minimum, so I have to clean out the weeds during the growing season. The last thing I want is flowers growing under my fruit trees, sucking up energy that I want to go into my fruit. Also, although I use composted manure on the tree circle, I think there remain some weed seeds, which makes it also a necessary disadvantage to maintain good tree health. I think a nicely maintained tree ring of dirt up to the drip line makes for a very attractive setting for trees. Also, since I cut my own grass, I'm thankful for not having to duck under branches to get the mower in close to the tree trunks. As mentioned before, mulch does wonders for all size trees in protecting them from loosing Winter moisture and insulating the ground from cycles of freezing and unfreezing. It is also a great slow release fertilizer.
Sherwin Dubren
gregpresley wrote:

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On Sat, 22 Nov 2003 18:09:18 GMT, "David Emerling"

Other posters have covered much of the ground here :-) so I will make only one point. The main advantage of mulching around the trunk of an established tree, other than the esthetic value, is that grass does not grow right up to the trunk therefore less lawnmower damage. Thin barked trees can suffer significant damage to the cambrium layer which is just behind the bark.
However, trunk mulch should not be too deep and should not cover the flare. That can encourage girdling roots which can eventually strangle the tree.
John
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On Mon, 24 Nov 2003 06:49:26 -0500, John Bachman
Will someone please tell me define the "flare" of a tree?
Thank you
Nick

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At the base of the tree where the roots "flare" out from the trunk as the disappear into the ground. All trees should have the flare above ground. Otherwise feeder roots might wrap around the trunk, that is called girdling. As the feeder root grows it strangles the cambrium layer that is just below the bark, killing the tree.
John
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Go look at a large tree. It will be at the base where the tree meets the soil. It flares out at the base. Smaller trees don't have an apparent flare, but they still do have one. If mulch is placed on top of it, rot can cause problems to the tree base.
V

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