Being in the woods makes me feel good – and one reason for this is the smells I encounter. To me, smell is an important way of experiencing the woodland environment. Just like the colours and forms of the forest, and the sounds of birdsong, smells change from season to season. Here in Comar Wood, spring is proceeding and the woods are waking up – gradually – despite the cold, wet weather we have been having. As the weather warms, smells start to be more noticeable in the woods.
The smells encountered in the forest include those emitted by plants, bacteria and fungi. The smells from plants are in the form of volatile organic compounds (VOCs) – chemical compounds that evaporate from the plant. Plants release these chemicals for various reasons, such as attracting pollinators, or repelling pests. Rain can trigger the release of aromatic compounds, and warmer temperatures allow more of the chemical compounds to be held and dispersed in the air, which is why smells are most apparent in warm, damp conditions. A chemical called geosmin, produced by bacteria and algae in the soil, is what creates the earthy smell of soil that is particularly enhanced after rain.
The VOCs are detected by the chemical sensors within our noses, known as the olfactory system. The way smell is processed in the brain means that smell is closely linked to memories and emotions. I find that smells have a great ability to stimulate memory, which is perhaps one reason why I enjoy using my nose to help me explore and understand the woods! Here are some of my favourite woodland smells. (Unfortunately it is not possible to convey smells via the internet – as far as I know – and I have found it difficult to describe the smells in any meaningful way, so I hope readers have a chance to get out into the woods and experience smells in their own noses!)
Once spring is in full swing, as birch trees come into leaf, they produce a sweet, pungent aroma. It seems more powerful in young trees, especially when there is a thicket of these, and creates an intense and wonderful smell after rain. In some of the native areas of woodland in Comar Wood, particularly along the roadside, bird cherry is abundant. Its white flower spikes in spring create a beautiful but short-lived display with an associated musky scent. The scent of bluebells in May is probably more subtle, but on a still morning the aroma augments the visual violet-blue of the flowers that carpet open parts of the woodland floor. Other woodland flowers that add to the scent experience include the smell of gorse (reminiscent of coconut) in spring, hawthorn blossom in late spring, and honeysuckle and heather in summer.
Into autumn, the earthy smells of soil, mushrooms and decaying leaves and wood are more pervasive within the forest. In our stand of aspen, up by the waterfall, leaf drop tends to be earlier than many other trees, after the leaves have turned bright gold. Walking through the fallen leaves on the woodland floor, many are beautiful gold, splashed with deep red, and the aroma released is distinctive and almost spicy. I’ve noticed it to be similar to the smell from fallen leaves from other poplar species. I expect other tree species could also be identified from the smell of their decaying fallen leaves if one’s nose became attuned.
Many coniferous trees have distinctive aromas that arise from the terpenes in their needles, bark and sap. These smells tend to be noticeable on warm days when aromatic compounds are more volatile, and become very apparent when the trees are felled. Scots pine has a very warm, sweet smell. Sitka spruce has a pleasant citrus smell that pervades in areas of felling and comes into the house on my work clothing. Douglas fir has a strong, sweet citrus aroma. I find inhaling the smell of a Douglas fir wood so intensely pleasant, and I think it ranks as my favourite tree smell.
I read recently that the human olfactory system is capable of identifying a trillion different scents1. However, I wonder whether by spending less time outdoors in nature than our predecessors, our noses have become less sensitive and less able to identify the subtle smells of different components of ecosystems. Smell certainly provides an important layer in my perception of the forest, but I am sure ancient hunter-gatherers would have had a much more developed ability to smell the different components of the environment in which they were immersed and depended on for their food and shelter.
It is well-documented that spending time in natural environments can be good for health and mental wellbeing. The smells encountered are likely to be part of this benefit, but it seems to be unclear what the importance of them is. Scientific research on health benefits of smells in nature seems to be a topic that is being explored but still at a relatively early stage. In my experience, being in nature, with natural aromas around us, as well as the sights and sounds of natural processes, provides a sensory experience that is calming, in contrast to the highly stimulating, attention-demanding environment that human brains are often confronted with in the 21st century.
Part of the enjoyment of spending time in the woods is the awareness of place, and being mindful in these environments helps to heighten the sensual experience and increase the mental and physical benefits, as practised in the art of ‘forest bathing’, promoted by the Japanese. This year I plan to spend more mindful, smell-focussed time in the woods to help further attune my nose to the array of smells over the seasons. By becoming more aware of the smells in nature around us we can heighten our experience of our beautiful planet.