I am a structural engineer designing a concrete box for planting a
bald cypress tree in. The box, with approximate dimensions of
10'x10'x10' will be
> placed in a concrete lined river channel. The projected area of the tree canopy will capture the wind and contribute to the overturning forces on the
> box. A maximum height of 40' is being given for the bald cypress.
What will be the horizontally projected area of the canopy for a tree
this size? Also
> what type of forces will the root system excert on the box as the
tree reaches maturity? Any help on this matter would be greatly
appreciated. Thanks

Reply to post by jack harrison, on February 08, 2000 at 09:23:21:

Jack,

Interesting set of questions and difficult to answer. As the tree trunk bends, the limbs bend, and the foliage rocks back and forth in the wind shedding load, calculating the actual force exerted is very difficult. It the darn thing was solid and would just stand still it would be a cinch!!

On a more serious note, you may have a greater challange keeping the tree standing if it indeed reaches 40' in a 10 x 10 container. The stresses exerted by wind on the above-ground portion of the tree will be transferred to the root system and will tend to tip the tree. In a natural setting the tree would compensate for the force of the wind by additional root growth on the windward side, but that is not a possibility in a container.

Something that may help is if there are some structural members that cross the interior of the planter perhaps 6 or 8 inches below the soil surface and 1/3rd in from the sides, the roots will grow above and below these and the planter then becomes part of the "foundation" helping the tree to remain upright.

Hope this is some help, even though its not much

Wayne

Reply to post by jack harrison, on February 08, 2000 at 09:23:21:

Hello, Jack. As Wayne points out, you have a rather complex situation.

Taxodium disticum grows to 70 or 80 feet tall, so your spec of 40 feet will require pruning or occasional replacement to maintain. Eventual branch spread reaches to 25 or 30 feet on a 40 to 50 foot tree, more on very old, spreading trees. Canopy shape for a young/mature tree will be roughly oval, slightly broader at the base (almost pyramidal). Again, it will change with age, the older trees spreading more at the top.

Keep in mind the dynamics of the wind- it is neither a smooth nor a solid surface, and the wind blows through, creating a drag on the branches all the way through the canopy, not just around the edges.

Will the planter box be anchored? The tree will need some way to anchor itself to the box, or else the root plate is likely to just pivot in the box and uproot. Wayne's idea of cross beams to allow it to support itself sounds logical.

One last item to consider is the transplanting of a tree. A large baldcypress that has been field grown will not be able to tolerate a sudden change to a submersed root system. I'm not sure how to go about getting the tree to adapt to a constantly flooded situation, but I do want to know if anyone has suggestions.

Reply to post by jack harrison, on February 08, 2000 at 09:23:21:

Jack,

In your quest for information on bald cypress, there is a cultivar known as "Shawnee Brave". It has a narrow, compact growth habit and would probably work well for the situation you described. There is an extensive collection of this tree growing at the Chicago Botanic Gardens and their are a few nurseries in IL that are growing it.

As for anchoring the trees, check out the Feb/2000 Arbor Age article, "Tree Care, Japanese Style". The article shows a unique anchoring system that is used in Japan to help the trees withstand the typhoon type winds that batter their trees.

Hope this helps.
Mike

Reply to post by Russ Carlson, on February 08, 2000 at 09:23:21:

email me on any information you have about transplanting bald cypress trees. i recently transplanted one 8' tall, but was only able to get 3' of the tap. Do you think this was enuff? Aniouxsly waiting!!!