As I raked up four big bins of leaves Monday,
I couldn't help thinking of all of the other Americans engaged in the
same chore. And yet, as always, I have it backwards. Here I
am raking up leaves out of the driveway, not to clear the driveway of
waste, but to salvage a precious resource. Isn't that mentality
at the heart of permaculture --- seeing nothing as a waste product?
I've been wondering which tree species have the highest quality leaves,
so I took a little time to search the scientific literature. The
best study I found was "Seasonal Nutrient Dynamics in the Vegetation on
a Southern Appalachian Watershed" by Frank Day and Carl Monk.
I've excerpted the nitrogen content of the various trees in the chart
above. I'm not surprised that Black Locust tops the chart since
the species fixes atmospheric nitrogen using bacteria attached to its
roots. What does surprise
me is that thick oak and rhododendron leaves, which I assumed were low
quality, actually have a high percentage of nitrogen compared to puny
little maple leaves. Although I can't find a value for Sycamore
(my current leaf of choice), I suspect it may be a high quality leaf
based on its phylogeny and texture.