Explanation of “overburden” and its removal
The root systems of a large fraction of Pines in Fort Zach Park are covered from a few inches to a foot or more with “something”.
What is it and how did it get there?
When the bottom of the channel was dredged in order to make a more effective Port of Key West in the late 1950’s, the dredgings had to be placed somewhere. That turned out to be what we now enjoy as Fort Zach Park. These dredgings were a calcium-based sedimentary material composed mostly of old coral. Not very inviting for most species but the Australian Pines are not fussy and grow where others will not.
The Park developed on its own for a while. Eventually it began receiving help from well-intended members of the Park Service. The original material of the Park made what some thought was a nice beach. However, it was sometimes rough on the feet and it tended to erode occasionally and become under-cut. The Park wanted a more friendly, stereotyped beach, so they undertook what is euphemistically called “Renourishment”
“Renourishment” in this case means importing silicon based non-native sand and dumping it over the nature beach. Instantly the beach is transformed into a beautiful-appearing “sand beach”. We all must admit that we like the smooth, foot-friendly sand. Hooray--but only for the short term.
As soon as a major storm occurs, the new sand is transported partly into the sea to disturb the virgin ecology of the sea plants--and partly on-shore where it covers--you guessed it--the root systems of the Pines! Over the years, several “renourishments” and many storms have resulted in part of the overburden we have today.
That is one way the overburden reached the roots. Some consider it natural because storm waters deposited it. It is more truthful to look to the proximate cause, which is the “renourishment” by dumping foreign sand.
A second way the sand gets over the roots is by the well-intended efforts to improve the Park through creation of roadways and paths, and the leveling of the grounds.
An effort to distinguish these two sources of overburden suggests they are perhaps very approximately equal.
Is overburden harmful to the Pines?
Laypersons have published their opinions to the effect that “Australian Pines can survive anything”, suggesting that removal of overburden is unneeded.
Realistically, only an experienced Arborist can answer this question. Such a well recognized and board-certified expert is C. Way Hoyt of Fort Lauderdale. After careful on-site inspection, Mr. Hoyt tells us that the overburden results in slow death by suffocation of the roots. His conclusion explained why the trees with most overburden had the most dead limbs. As the pruning of all trees was only recently completed with all dead limbs removed, this correlation is now difficult to observe.
All concerned have accepted C. Way Hoyt’s conclusion. It is the basis for the phraseology of the Memorandum of Understanding in which both parties agree to removal of the overburden.
How should Overburden Be Removed?
This has been the subject of technical discussions among Park management, Park technical experts, and C. Way Hoyt. A Bid Request was issued and potential contractors have responded.
There is recognition that the method selected must not only remove overburden without damage to roots, but must also minimize the impact of the work itself on Park visitors. Therefore, it seems likely that work will be scheduled later in 2009 at a time when attendance is minimal. The method to be used is still being considered by Park management.
As always, for more information, please contact us. Thank you!
