Don't know it this will help. It's an excerpt for Weeds: Guardians of the Soil. An amazing book, out-of-print but available online at
http://www.naturalsequencefarming.com/press/Weeds%20guardians%20of%20the%20Soil%20(3).pdf
Her words brought back days in the Indian country when I often
tramped the woods and hills with a hunter-naturalist who used to say to
me: "If you wanta scare up deer on a blizzardy day, always make for a
weed patch that ain't too close to any house. Weed patches are warm
even in coldest weather, and the deer know it."
One spring back there in those boyhood days I decided to explore the
soil in one of my favorite weed coves, with the hopes of discovering
just why it should be warmer than the surrounding land. My patch
consisted mostly of giant ragweeds, or horseweeds, bordered by annual
common ragweeds and thistles and mint. Being quite young and
unlearned in the science of geology, I at first imagined that Mother
Nature was sending the heat from the interior of the earth as a special
favor to weed coves -- or to the deer and other wildlife that sought
warmth in such coves. But the further I dug into the soil of my cove,
the more I came to suspect that the horseweeds themselves were
responsible for the warmth. How -- I hadn't the slightest idea then.
It was not until many years later that I learned why the deer could
depend on weed coves to supply them with warmth on frigid days. The
soil in such a cove is close to being an ideal organic soil, composed
mostly of plant materials in various stages of decay. And since the
bacteria that are largely responsible for transforming the weeds into
humus are very active and persistent workers when conditions are
favorable for them, as conditions are in a virgin weed cove, a great
amount of heat is being continuously generated. In such situations the
bacteria keep up their work to a degree, even in winter. This heat is the
heat of decay
