The most important function of a forest is something that we will never see. It is called fragrance. Trees and forests from the tropics to the Boreal, all produce some sort of smell. The older the forest, the stronger the smell. The most ancient word that I can find for this kind of smell is úd going back to very old Gaelic, meaning the fragrance of the forest.
As a biochemist, botanist and organic chemist let me put some pieces of the fragrance puzzle together for you. On an ordinary day in an ordinary home your nose keeps you alert to the variety of different smells around the space you occupy. For the most part many of these smells are neutral tones to the working body. A few are toxic. These arise from the gassing off of polymers from artificial fabrics on floors, walls and furniture. Many people try or have to avoid these synthetic materials.
There is a new science about the ability to smell. It is not just confined to the nose. There are odour sensors called olfactory receptors in the body, about 350 of them on the last count by the team of Dr. Hanns Hatt of Rhur University, Germany. These sensors change the playing field for the future of medicine and will provide an extraordinary way to handle health. A smell is registered by the body as it travels to the edge of a cell where it is picked up by a specialized fishing line called a neurotransmitter. This neurotransmitter moves the fragrance molecule within the cell where it becomes a miracle worker.
Smells can boost the immune system producing healing, regulate the heart producing more normal blood pressure, affect certain feeding arteries over others, stem strokes, and even inhibit the spread of prostrate cancer by the inhibition or shutting down of rogue genes. One of the more familiar ones is the smell of roses called beta-ionone. It is also found in many forest tree species.
A working mature forest, anywhere, produces the maximum diversity of úd, or forest fragrance. These smells are complex, mostly aromatic in chemistry and arise from the soil mycorrhiza of the forest floor, and on the periderm of the powdery material found on the bark of many of the tree species. Smell arises from the forest floor perennial or annual plant species either above ground or from things living in the ground like the mushroom dynasty. They also come from the hidden, endophytic, small fungi within the plumbing of the tree’s anatomy. Smells emanate from the scent glands of leaves, flowers and fruit and from the complex medicine of the tree itself, the phenolic marvel we call resin.
On an ordinary morning in an ordinary working forest the sun lands on the leaves of the canopies. A hot button for fragrance is pressed. The leaves have come p0repared, they have squeezed out one drop of honey-dew on all the edges of the veins of each living leaf. Each drop is held in place by surface tension. The heat of the sun warms the surface of the leaf through the cuticular window and the fragrance factory starts up. The humidity form the honey-dew acts as an aerial vector for the forest, picking up scents and smells. All the volatiles mix and match into a fragrance that differs with the seasons and even with the time of day or temperature gradients.
Hidden within this humid air is the treasure trove of the green forest world, exactly matched, to the human nose. The smell is woodsy and sweet, filled with moisture vapour that can readily deposit the healing mixture of aerosols on the skin or into the lungs. Forest perfume comes in many chemical forms. Sometimes it is a single molecule, alone and floating. Other times there are two or three molecules, one helping the other to remain airborne giving it lift. The biodiversity of fragrance is huge.
The forest was the first playground for the ascent of man with all of his hopes and desires. This is the basis of úd. This is the physiology behind my North American Medicine Walk in my garden. It has taken 450 million years for the forest to come full circle to help, to heal us today into tomorrow.