Trees on Slopes:

Some arborists have assumed that tree roots are incapable of exploiting soils on the upper levels of a slope. Given that tree root matrix morphology and the tree's structural adapatation; do tree roots exploit the extreme upper levels of a hill side and where do you expect the rooting matrix to be in order to maintain structural stability and maximum absorption of moisture and minerals?

In other words: What do tree's do on hillsides and where are their roots?

Paul H.

Reply to post by Paul H, on October 30, 1998 at 19:40:51:

Paul,

From observations of trees growing along washed out stream beds and other such sites, I know that roots will grow up hill from a tree. Since the limiting factor in most cases for root growth is air in the soil, I would assume that growth uphill will continue to be in the upper layers of the soil, proceeding fastest where conditions are most favorable. Therefore, there will likely be a little less root system at the very top of a hill covered with gravel or other well drained media. I contend the roots grow out in a roughly radial pattern to start with and this pattern is only altered by encountering physical obstructions and by availablility of good growing conditions.
The attached Image URL is a picture of a Acer rubrum that was cut off at ground level when it died. Upon replanting I dug up the roots and found that it was buried a "little" too deep. The soil was a very heavy scalped clay and as you can see, the roots tried to go up to the air, but other conditions predisposed it to an early end. This shows that roots do indeed grow uphill, if conditions are better for growth in that direction.
My thoughts.
Bob

Reply to post by Bob Underwood, on October 30, 1998 at 19:40:51:

Your photo on red maple roots is much more a statement about trees planted too deep than one about roots growing uphill. It's another example of a horrible nursery practice of planting their liners too deep, then having the victimized homeowner or contractor think they are doing the proper thing by planting the root ball at grade or a bit above, when in fact they have buried their tree alive. 10 years later, the results show up, varying with species, with girdling roots, rotten trunks, and stunted growth.

Marmon Thompson
Charlotte, N.C.

Reply to post by Marmon Thompson, on November 02, 1998 at 10:27:53:

I've seen alot of ornimentals burried to the graft scar, and been told that this is proper. And people wonder why Malus, Prunus, and Sorbus all sucker so much more than other trees.