Live Oak's Chemical Warfare

Hello,
I've been doing some research on the subject matter of Live Oaks. I noticed that the leaves they drop essentially break down into a chemical composition that makes it difficult for smaller plants on the ground to grow. I was wondering if anyone knew more about this. I would like to know if there are any natural solutions out there from any of you fellow permies.

Any input would be greatly appreciated,

Dan Jerome
Palm Harbor, Florida

I regularly use oak leaves as mulch. It's a common organic amendment in my area. I've never seen in harm any plants we apply it on. Even the juglone that has been documented from plants like black walnut or pecans does break down as the leaves degrade.

I think the biggest reason you don't see much growth under established live oaks is the competition for light and water. I've noticed the shape of our local live oaks creates something like a cave that blocks light under the canopy and directs rain fall out to the edge of the drip line rather than covering the space near the trunk.

What chemical is it that is supposed to be causing the problem?  I agree with Casie that it is the dense shade and root competition which are the problem with Live Oaks.  

I believe it's called allelopathy. It's the process in which the Live Oaks leaves and roots produce a chemical barrier which prevents most plants from germinating. I've been having trouble finding the links that I took my notes off of. I've been looking all over for the links today. I do know they were from some colleges. I seem to have a problem with young plants on the northern side of my garden. A few people have suggested that there are too many oak leaves in my compost this year. My garden is on the southern facing side of a large Live Oak tree as well. There is plenty of light and water. It's been raining a lot here lately and I water my garden on a regular basis.

Thanks,
Dan Jerome
Palm Harbor, Florida

Searching for "live oak allelopathy" seems to turn up a lot of people saying that live oak is allelopathic but so far I can't find anything mentioning what chemical is the problem, or how much of a problem it is.

This paper suggests that high concentrations of oak leaf might be a problem:  http://slosson.ucdavis.edu/newsletters/Raabe_199129122.pdf

Growing up in the San Antonio area of Texas it was generally considered a bad practice to use large amounts of Live Oak in your compost.  That being said all I have is 'old wives tails' that basically indicated the the Live Oak leaves were to acid (Tannic?) to be a good compost and that your compost should only contain at most 1/4 to 1/3 Live Oak leaves.  But like I said it is just 'old wivws tail' stuff and I never investigated it just adhered to 'common' knowledge.

i have a huge live oak out the back and i've been looking into what i can plant under or near it. it currently has some grass from the previous owner that's the sort someone might use for a lawn. but no one is going to mow a steep hill like that. so i was hoping to plant berries to both hold the hill and feed the birds. i found that berries native to my area love to grow near the tree's drip line and wood strawberry, ponysfoot (sp?) torry's melic, will grow as ground cover in the deep shade. the live oaks by me need their leaf litter to break down slowly to encourage the mycelium that grows on it's leaves as they decompose and benefit the oak. my tree had over 5 inches of leaves and i think it only needs about 3. so i took away a couple of inches and used it as mulch in other areas. it's important to leave the leaves and only sparsely plant under the kind of live oak i have. i get alot of info from this site, it has a whole page on what to plant under live oaks http://www.laspilitas.com/groups/oaks/Planting_under_oak_tree.html. the site has alot of ideas consistent with permaculture. he urges people to examine where they live and determine what particular nitch ecosystem they are part of and to learn about the plants that are supposed to grow there, that want to grow together. http://www.laspilitas.com/nature-of-california/ecology http://www.laspilitas.com/nature-of-california/ecology  even if you are not in calif. there's alot of info on this site.

Bear in mind that the California live oak is different than the southeastern one (Quercus virginiana).  The oaks in FL do acidify the soil (great for blueberries, poor for cabbages) but otherwise their leaf mould seems fine.  They do cast extreme shade however.  Not many plants will grow in a dark closet.  (Well, an old oak can cover quite a lot of ground, so maybe that was the wrong analogy.  Nothing in the upper  midwest is even a tenth as wide.)