And still more...this time the topic is Tree Roots, do they really "stabilize" soil?The Canal Corporation has been very clear on this subject, and have stated it several times... No Trees on Dams. The main reason is because tree roots negatively affect the stability of earthen dams.
Here's the TRUTH from a FEMA Technical Manual on Plants near Dams that is being used to guide embankment maintenance:
https://www.fema.gov/sites/default/files/2020-08/fema-534.pdfChapter 3- Tree Growth and Tree Root Development RequirementsThe purpose of this chapter is to provide the reader and user of this Manual with a basic understanding of plant physiology related to fundamental processes of tree growth and tree root development. It is not the intent of this chapter to delve into a detailed biological
study of trees and woody vegetation, but to provide the reader with a fundamental understanding of the requirements for tree growth and tree root development while attempting to dispel some of the misconceptions and myths associated with tree and woody vegetation growth, particularly as related to tree root development.
Common Myths and Misconceptions: There are many misconceptions and common myths relating to trees and woody vegetation that have been accepted by many people without a scientific basis. Many of these common myths and misconceptions relative to plant physiology have originated from uneducated interpretations of observations associated with tree growth and tree root development. Some of these myths and misconceptions associated with trees and woody vegetation affect correct interpretation and understanding of the impact of such growth on the safety of earthen dams.
Tree Root Soil Stabilization is likely
the most common misconception associated with tree growth and tree root development. How many times has the reader heard, or perhaps mistakenly said, “If it were not for those trees and tree roots this slope would really be eroded or unstable – those tree roots are really ‘holding’ that soil slope”.
Many otherwise knowledgeable and educated individuals believe the myth that tree roots actually stabilize soil masses by ‘holding’ the soil together. This misconception leads many people to believe that heavy tree and woody vegetation growth is actually beneficial for steep embankment slopes.
Tree root development that is necessary to provide nutrients for tree growth and stabilize the tree actually loosens the soil mass. And what does a Facebook Group say about this soil stabilization topic?Well the group's founder says it all...they want to believe the "myth", even though it's actually untrue.From the STCC Google Website:
...it is clear from the the structure of the embankments that they are not made of compacted earth the way a dam that creates a reservoir is. They are piles of dirt, whose stability may, in fact, depend on the roots that form a dense network within them.
The first clue that this document lacked input from plant biologists and ecologists is this eye-popping statement, that the well-established fact that tree roots do in fact stabilize soil, is a "myth", and that roots in fact "destabilize soil".
Where did this statement come from?The STCC asked who wrote this statement that is OPPOSITE of what they want to believe?
It's from the people who cleanup AFTER floods happen, and the group responsible to insure Dam Safety is maintained in our country FEMA...and FEMA is stating that this STCC Facebook Group believes a MYTH!!!