Wildscape: How the sense of smell influences life in our gardens
Scent can be a matter of survival in our woodland gardens
The smell of a spring rain, or the scent of jasmine wafting over us is a memory often ingrained in our minds. They bring us back to our youth or perhaps happier times on a vacation, or spending time with friends.
To the butterfly, however, fluttering over our heads or the fox stealthily roaming the back of the garden, these pleasant smells that awaken our senses, are nothing compared to the really enticing smells of pheromones gently spreading out over the garden.
Nancy Lawson’s book Wildscape explores the senses in the garden including how scent plays a role for animals, insects and other garden inhabitants.
We really have no idea what the gentle breezes are bringing to our garden inhabitants, from the tiniest of insects to the largest of mammals.
Wildscape is a follow-up book to Nancy Lawson’s highly acclaimed book The Humane Gardener.
In her latest book, Wildscape (PA Press, Princeton Architectural Press, New York) Lawson explores the sensory wonders of nature and the incredible adaptations insects, mammals, birds, reptiles and amphibians are sometimes forced to make to survive and prosper in our gardens.
For more on Wildscape, check out my reviews on
• How sounds influence our gardens
Take a moment to check out my comprehensive review of The Humane Gardener.
If The Humane Gardener, was a plea for respect and compassion toward all species and a call for gardeners to welcome all wildlife to our backyards, Wildscape is a call to action for gardeners to recognize the problems humans are creating and how our actions are, in many cases, forcing garden wildlife to change natural behaviours to survive.
Nancy Lawson, in her book Wildscape, Trilling Chipmunks, Beckoning Blooms, Salty Butterflies and other Sensory Wonders of Nature, brings it all into perspective in the opening chapter of her book.
How animals, insects and reptiles use scent in our garden?
“Of all the sensory inputs experienced by our wild neighbours, their olfactory world may be the hardest to grasp, reliant as it is on the ever-changing conditions that are largely amorphous. It’s difficult enough to comprehend that the world is full of colours outside our visual spectrum and sounds too high for us to hear. But many odours are so fleeting and so malleable, constantly mixing together and dissipating, that understanding and describing their structures is even harder than catching sand in a cracking bucket; you might grab some momentarily but lose others, never quantifying how a given scent compound runs its course in the natural environment, let alone all the organisms catching its drift.”
Lawson goes on to explain how useless the human olafactory systems are in detecting “unseen and unheard communications.”
So, all this unheard communication is going on in our backyards and, unless we know what to look for, we’re missing it all.
“As mammals, we can sense fear and anxiety through our scent receptors. Odours lure us to mates and warn us of spoiled food and impending calamity. But it’s possible to lose our sense of smell and still survive,” Lawson writes.
Humans’ dependence on sight and sound, Lawson explains, has diminished our ability to both smell and, to a lesser extent, recognize how much better the animal world’s olfactory operates in comparison to ours.
Lawson explains that it was only in the last 50 years that researches recognized that more than a handful of birds could even smell. Frogs too were thought to lack olfactory abilities.
“Only recently have researchers begun to understand the social and scent-based dynamics of creatures like snakes, discovering that they too commune with friends, defend young, and babysit for one another.”
Obviously, scent plays an important role in our gardens when it comes to finding mates, but it can also be crucial when it comes to staying alive in a very dangerous environment.
Lawson uses the example of a variegated fritillary caterpillar “shooting poop” as a means of not giving away its position to predators. That same defensive practice can be seen with parental birds who fly their nestling’s poop far away from the nest.
Studies show that bee balm emits odours to keep insects and mammals from eating it.
Do plants use the sense of smell for survival?
It’s easy to think that only insects, mammals and other creepy crawlies use scent to survive.
But you would be very wrong. The plants that we all love so much in our gardens depend on scent for survival.
Lawson tells the story about a researcher from the University of Wisconsin who discovered how bee balm used odour to fend off an attack by one-spotted tortoise beetles to the point where he was almost overwhelmed with scent when he walked into a field of it in the mountains.
That scent that the plants released, the researcher later confirmed, “when he found that chewed-on wild bergamot leaves released twelve times more volatile compounds than those left intact. As members of the mint family, wild bergamot and other bee balms release strong monoterpenes, the compounds that give essential oils their aroma and flavour, in tiny sacs on their leaves and flowers called trichomes. Just rubbing a leaf is enough to create a powerful scent that keeps most other herbivorous insects and mammals at bay.”
How do we affect scent in our gardens
It’s not enough to know the importance of scent in our gardens. More important is how odour pollution is interfering with our garden’s ability to function properly.
Lawson explains the problems bees and other insects face because of general air pollution and the fact that ozone is pulling odours out of the air into the upper atmosphere. But, our gardens are more affected by local odours that work to Jam our garden inhabitant’s ability to take in the smells they need to survive.
She cites a 2013 UK study that showed that when floral chemicals were exposed to diesel exhaust, the scents were so altered that few honeybees could recognize them anymore.
Studies also showed that the presence of fungicide confused bumblebees, increasing the time it took for them to find flowers. “When given the choice, they also showed a significant preference for fresh-air pathways over those contaminated by common lawn fertilizer.”
Need we say more? Yes.
To wrap up the chapter on scent, Lawson raises an important argument for leaving our gardens to die naturally, to decompose on their own and to send out that scent of decay that is so important to so many of our garden inhabitants.
“Though I have been leaving fallen logs and leaves and leftover stalks for years in my wildlife habitat, I was just as surprised as Brice (a young boy she was communicating with) to learn of even more ways that butterflies and bees could use such detritus too. Nature has shown us both that there is more life after death than we could have imagined – including on decaying and broken wildflowers still standing and still sending their invisible scents into the aerosphere, a final gift to animals during their descent back into the earth.”