What must it be like to live life as a eucalypt? Before studying plants, I always thought that it must be quite a relaxing life, planted solidly and soaking up the sunshine. Now, after learning more about what is involved in a plant’s life, I know that for many trees, and in particular our eucalypts, daily life can be quite stressful. I recently read the book The Hidden Life of Trees by Peter Wohlleben, which highlighted many of the trials that trees are constantly facing. These included such hardships as being under threat from herbivorous animals, their competition against neighbouring tree species, and the fight against the slow, yet insistent fungi that can cause a tree to rot.
Whilst reading this book, I thought keenly about the hidden behaviours of our own eucalypts in Australia. There is so much that is not fully known about these wonderful trees and little shared about their experiences. This National Eucalypt Day, I would like you to imagine what it must be like to live a day as a eucalypt tree.
It is early morning on a summer’s day and the first gleam of light is about to peak over the horizon. You feel a light breeze ruffle your leaves just as the first beams start to hit your upper branches. You slowly angle your leaves to capture as many of the sun’s shafts as you can and start the day’s conversion of sunlight into sugars, releasing the oxygen created as a by-product.
You pull water up your trunk from your roots and feel it extend through your branches and into your leaves. This is something you do all day and for many eucalypts in summer, it can be quite a struggle when there’s little water around. You make the most of the early sunlight whilst the temperature isn’t too hot and reduce the amount of water you lose from your leaves.
As the day warms up, you start to pull more water up to your crown. It evaporates off your leaves, keeping you cool for a while, but eventually the temperature, particularly in the afternoon, gets too much for you. You close your leaves to the surrounding environment and slowly angle them away from the direct sun. You wait out the hottest time, storing your sugar reserves for later.
As the sun goes down, you open your leaves again to the air around and start letting oxygen and carbon dioxide flow. You use your evening of free breathing to slowly fuel the growth of more leaves, your trunk, branches, roots, flowers – everything. You also use it to produce the oils in your leaves that make you smell so wonderful, and taste so terrible to any interested animals.
You continue the slow movement of materials through the night into the next day where it starts all over again. As a eucalypt tree, you are rarely hungry, nearly always thirsty, and can only breathe when it’s not too hot. You continually store as much energy as possible so that there are always reserves should any unforeseen circumstances come to pass.
The above narration captures a tranquil day in a eucalypt’s life. But what happens when there are strong winds, an insect boom, flooding rain, or a bushfire?
Our trees survive through extraordinary conditions and display incredible behaviours in response to the daily and long-term changes in their environment. Unfortunately, most of these are hidden from everyday view or are on timescales that go unnoticed to the untrained eye. I am endeavouring to appreciate these behaviours in my local eucalypts and am on the look-out for secrets I may have previously been ignorant to. Next time you wander past a eucalypt, or sit under its most welcome shade on a hot day, spare a thought for its efforts and see if you can notice any of its more unobserved habits.
Sarah is a botanist who works at a local indigenous plant nursery in Melbourne. She is interested in engaging the public with the conservation of local flora and fauna.
You can find her on Twitter at @SarahBBond