Tree roots and water filled ditches:

Roots exploit less hostile soils? however, can they delve across such extremes, through anerobic territory and up slopes in order to encompass the surrounding neighbouring land?

If a tree is on one side of a water filled ditch, where do you expect the majority (if not all) of the rooting matrix to establish itself?

Paul H.

Reply to post by Paul H, on February 04, 1999 at 17:48:24:

I wouldn't expect "uphill" or "downhill" to make much difference to root development. I believe that geotropism would be less of a developmental influence than would moisture, nutrient availability, soil tilth, and many other controlling factors.

I haven't seen much research, but have considerable field experience in swamp conditions. Even swamp trees like redbay, tupelo and baldcypress seem to PREFER aerobic soils, and might actually require aerobic conditions for seed germination. Prolonged inundation leads to "knees", buttressed roots, and other adaptations to maximize oxygen access. Most tree swamps here in Florida are shallow enough to dry out, at least every few years, if not annually. Areas that are continuously wet are generally tree free.

According to some sources, the reason that they are relegated to the swamp in the first place seems to be more a matter of being out-competed in the uplands, rather than an actual preference for the wetter conditions.

In short, I would expect to find MOST of the effective roots above the water table. A drainage ditch is, of course, merely where the water table is exposed to the surface. So most root growth would stop right at that level. Whether a tree would send exploratory roots below the water table, to pop up on the other side of a continuously wet ditch, is a possibility. However, I wouldn't expect that a tree would derive a significant degree of nourishment in that manner.

Reply to post by Paul M Davis, on February 04, 1999 at 17:48:24:

Paul, there is the possibility of a perched water table, and also of an intermittently high water table.
If the water table is high while the temperature is low, then fungi won't exploit the root tissues. Then if the temp goeth down while the soil dries out, unless it is also compacted, the effect on the roots might be negligible.