Saturday, November 19, 2016
In northern climes like the Adirondacks of New York, abandoned beaver ponds that evolve into wet meadows are slow(up to 70 years) to take the next ecological succession step to forest.................Whereas in an upland forest where a blow-down or a fire burn knocks out the woods, the next few years bring in an immediate tangle of raspberries, birch and red cedar trees-----In a Beaver Meadow, there's something missing in the soil that the black spruce need to survive; That something is mycorrihizae fungi, the underground fungus that connects across the roots of the individual trees of the Spruce woodland....................This fungus does not survive the water drenched Beaver meadow as it does in the soil of a blowdown or a fire impacted upland Spruce forest...........The abandoned and drying Beaver meadow has to wait for a rodent "superhero" to come on the scene and kick start the Spruce Forest.................. The Red-Back Vole does this by eating the fungus in the woods and then "pooping out" those spores in the meadow,,,,,,,,,,,,Enough spores get deposited in the Meadow, making the soil receptive to the Black Spruce seeds when they sprout into seedlings................Fascinating stuff all this is reinforcing how how everything in nature is a "team sport",,,,,,,,,,,,the circle of life in constant motion
Nov 17, 2016 — Tall trees may be the kings of the forest, but there is another kingdom of forest life that passes unnoticed. Dr. Curt Stager and Martha Foley talk about the arboreal network of fungus.
Martha Foley: Two tidbits about fungus. One having to do with why beaver meadows, where the beaver pond has dried up and gone away, why that doesn't spring into woods all of a sudden. They generally stay grassy instead of being repopulated by the spruce trees or whatever.
Curt Stager: It's sort of a mystery because at first glance you'd say, okay, it should be pretty fertile soil because it was a pond and collected all this nice crud and organic matter. Okay, it's a little bit damp, so that would keep out a lot of trees, but there are trees that like that.
MF: Right, the spruce trees.
CS: The black spruces like it and if you have a beaver dam that eventually washes out and you get this meadow it can sit there for 50, 60, 70 years.
MF: Yeah they're beautiful, but why don't trees move in? I mean, if you had a blow-down in the forest or a place where it burned, in the next year you'd have raspberries, and birch trees, and all sorts of stuff.
CS: Yeah, and so there's got to be something fundamentally different about that whole issue. There was a recent study published in the journal Nature that looked into this and they think they've got it nailed down now. It's that there's something missing in the soil that the black spruce would need to let it survive besides just the nutrition, the dampness, and all that kind of stuff.
There are actually fungi in the soil that connect with the roots, which is really common for most forest plants. It's symbiosis going on. The technical term is mycorrhizae, where the plant roots and the fungi combine and they both share the water and the nutrition in the soil and help each other out. And in some cases it's actually quite specific, and black spruce trees actually have a specialized kind of mycorrhizae fungus they need connected to our roots.
MF: And it doesn't survive underwater, so it's not there when the beaver pond dries up.
CS: Right. But if you had something like a fire or a blowdown, normally, then the fungus is still in the soil and the seedlings can start up no problem.
MF: So eventually the fungus gets back in the soil, and then the spruce can come back?
CS: Right. But then the question is how do you get the fungus back into the soil.
MF: Little seed packets! You go out and you buy them at the spruce store and you spread them around.
CS: Well, sort of. Yeah, it was actually like little seed packets only it was rodents, these voles, red-back voles, that like these kinds of meadow habitats that eat the fungus that's growing out there in the woods. They get the spores in their digestive tracks, they poop in the meadows, and that's how the spores are apparently dispersed. So the idea is it probably won't turn into a forest until something like those voles will move in eventually. So maybe you should raise red-back voles.
MF: I know voles. Yes, thank you. I'm not going to be raising them. Tidbit number two: also having to do with fungus and trees. Cherry trees.
CS: In this case it would be fungi in the soil again, but its ones that are bad for the trees. In a lot of temperate zone forests where there are black cherry trees growing wild they usually don't form dense stands. They're usually pretty widely dispersed.
Some ecologists that study forests in the tropics have noticed that. Down in the tropics that's a common pattern for forest trees, for one to be over here and one way way off in the distance. The idea for that was that there's probably some sort of insect or other animal that attack the tree and if you drop your seeds right there, that your seedlings will all get killed.
So there's an advantage to dispersing over a large distance. These ecologists have been looking at the cherry tree story up here in the temperate zone and they think it might be similar, but have to do with fungi in the soil instead of above-ground attackers.
MF: You mean there's a fungi that discourages the growth of little cherry trees and so the only way they can survive is at a distance?
CS: Yeah, when they look around it turns out there is a fungus that grows and entangles in the tree roots and it doesn't necessarily kill the adult tree, but when the seedlings try to sprout it knocks them off and so they're dispersed out. It's interesting that what was normally considered tropical forest ecology is actually going on up here in the temperate zone maybe in a slightly different form with these soil fungi instead.
When the flow of water in a stream is slowed by the beaver dam, soil and organic sediment carried in the water usually settle to the bottom of the beaver pond. When beaver subsequently abandon a locality, their dam eventually breaks and the pond drains leaving a large open space. A meadow usually grows on the nutrient-rich soils that once formed the bottom of the pond. These "beaver meadows" usually have more light penetration, higher soil moisture, more nitrogen and a different vegetation than the adjacent riparian forest (Johnston et al. 1995; Wright et al. 2002).
Effects of beaver engineering on wildlife
Beaver engineering alters the distribution and abundance of so many organisms, that we cannot mention them all on this page. Therefore, we have produced separate reviews for different groups of animals and plants affected by beaver engineering. Click the following links to learn more about the effects of beaver engineering on specific species of plants and animals:
Posted by Rick Meril at 8:49 PM