Can anyone suggest any good books or articles about root zones, dealing particularly with root growth patterns. My basic understanding is that roots will grow yearround as long soil temperatures remain between 42 and 98 degrees F, with bursts of grow in the spring before bud break and in the fall as leaves are falling. I'd appreciate any corrections or additional information along with literature suggestions. Thanks, Tom

Reply to post by Tom Watson, on March 09, 1999 at 00:33:38:

I omitted a word in the second sentence. The incorrect phrase should read "as long as soil temperatures remain..."

Reply to post by Tom Watson, on March 09, 1999 at 00:33:38:

Tom,

It is my understanding that roots grow radially and symetrically wherever the resources of life exist (oxygen and water). From there the complexity of the site begins to control location. Foundation walls, rock outcrops, low oxygen environments will all affect the "radially and symetrically" model. I have heard and taught the 40F threshold for root growth but cant for the life of me find out where I learned that......

Wayne

Reply to post by Wayne Cahilly, on March 09, 1999 at 00:33:38:

I have seen the 40deg explained as a rule of thumb (ROT) some northern zone plants can do it at lower temp's.

Since you brought up the presance of O in soil as a limiting factor, dose any one know about lit. on riparian/floodplain plants that transfer O to the roots? I have heard that some Willow and Silver Maple can do this.

Reply to post by John S, on March 09, 1999 at 12:34:47:

Might want to look at western red cedar (Thuja plicata), baldcypress (Taxodium distichum), and white alder (Alnus rhombifolia), a nitrogen fixator. I have seen all with very wet feet & apparently doing very well.

Have dropped Pacific willow (Salix lasiandra)brush into slow moving water and found it rooted six months later. When observed, the original cutting was upside down, and new growth is heliotropic in six months - not observed earlier than 6 months & do not remember the season. Pretty impressive, though.

Don't understand where any of the above was obtaining free oxygen. Would like to hear of the progress of your study. So far, it's an enigma to me.

Reply to post by John S, on March 09, 1999 at 12:34:47:

Some of what I know has come from "physiological Plant Ecology" a text by Springer-Verlag and "Terrestrial Plant Ecology" by Benjamin Cummings publishers. Flood plain trees apparently have a lower gas exchange rate with the atmosphere and therefore can tolerate lower O in the soil. Some plants "Taxodium" for instance produce roots at the surface or "knees" which may improve the O for CO2 exchange.

I suspect there is a lot we need to learn here

Wayne

Reply to post by John S, on March 09, 1999 at 12:34:47:

Once the roots of Bald Cypress is dried, you can blow air through it like a soda straw. The cells are large enough to see quite easily. Do any of these transport air while alive? I know they root very deep in heavy dry clay in Illinois and do not develope knees under those circumstances.
Bob

Reply to post by Bob Underwood, on March 09, 1999 at 19:05:06:

Bob,

I do not know. Nearest to you I have observed them is N. Arkansas.

David

Reply to post by Tom Watson, on March 09, 1999 at 00:33:38:

Shigo has reported root tips of some northern temperate trees to be growing within milimeters of frozen soil. And until frozen, the root cells must still respire to some extent.

Reply to post by Tom Watson, on March 09, 1999 at 00:33:38:

Fine roots are ephemeral. They are constantly appearing and disappearing. Fine roots are unsuberized (suberin is a waxy coating). They have no secondary thickening (from lignin). They are very vulnerable to abiotic and biotic changes. They are like our intestinal walls, and when they stop being produced, the tree must survive on stored carbohydrates. Just like us.

Reply to post by David Cory, on March 09, 1999 at 19:05:06:

Willows make great nurse logs, the'll root almost anywhere.

you said that the logs were ubder water? did sprouts grow above the surface of the water? If so this is what I was "talking" about some plants may be able move the O down from the foliage to the roots instead of dumping all of it into the atmosphere.