The life of a Canberra leaf

Every autumn when trees start to change their colours we anticipate the variation to come. The shifting colour of a leaf signals a change in seasons from warm to cool and hot to cold. Some trees treat us by delivering a natural show of colours turning from green to spectacular yellows, oranges or reds before turning to brown or dropping off the tree. Deciduous trees can bring so much joy!

Photo credit: Andrew McAuley

Have you ever thought of a leaf as a living thing that goes through its own life journey? Just like our own life journeys, the lifecycle of a leaf can be told as a story. Some stories feature a hero or a heroine, others a villain, and some stories include a bit of both characters. Life journeys can take many different turns, and we wonder at times what our stories will look like. Are we on track to be a heroine, a scoundrel, or some other character?

Now take a moment to think about the life of a leaf.  Leaves start their lives unfurling on a tree. They grow to full size and together with their host deliver shade, a home and food for many creatures! Trees cool our streets, parks, suburbs and nature areas providing shaded relief from our hot Australian summers. Creatures great and small rely on trees and their leaves for their very survival. We like to think of any individual leaf’s life journey as a choose your own adventure novel. Some leaves get eaten at early stages in their lives. Others make it to full size. Some get eaten at full size and yet others survive a full season or in the case of eucalypts many years. If an individual leaf from a deciduous tree is lucky enough to escape attacks from insects and the other creatures across its entire growing season then one thing is for certain. It will fall from the tree! As temperatures change, the next stage in the leaf’s journey begins. Read more about the genetic program triggered for a deciduous leaf in Autumn here.

No journey is the same and a leaf can take many unknown adventures during its lifetime that ultimately determine its fate. Fallen leaves can nourish and live on or they can negatively disrupt natural environmental areas.  In large volumes they can become our heroes delivering carbon for composting or they can form an alliance and be villains contributing to algal blooms in waterways.

Leaves from the deciduous trees that bring us so much joy, can end up in our water drains if we simply leave them where they fall. All it takes is a few gusts of wind or some rain, and those fallen leaves will travel into the gutters and get closer to drains. Once down a drain leaves follow the storm water system, eventually ending up in a big collection point. In a storm, leaves can end up going straight into our lakes and this is where damage occurs. Leaves are designed to break down and they do so faster in water. When leaves break down they release all of their nutrients. The nutrients released by leaves ending up in Canberra lakes are creating food for algae.

Lake Burley Griffin Algal Bloom May 2021

Source credit: Andrew McAuley

When there are extreme algae blooms, lakes can’t be used. For example, during blue green algal blooms people and dogs can’t swim in Lakes due to the toxicity. Did we mention that algal blooms can also smell, look ugly and be harmful for many different forms of wildlife too?

Most of us don’t realise that an organic material source such as leaves can actually become the story’s villain. When left to accumulate in verges and in gutters they inevitably finish up wreaking havoc in our waterways.

Drains adopted during the 2021 Leaf Collective pilot (before pick up)

Source credit: Leaf Collective 2021 Participant

Yet the ending does not need to be all doom and gloom, the beauty of this story is it can be re-written. The actions we take during the leaf’s journey can stop any leaf from becoming a villain. We can ensure the leaf is always the story’s hero or heroine. By picking leaves up and putting them into your own compost, or a green closed loop system we can make all leaves the heroes and heroines we always believed them to be.

Drains adopted during the 2021 Leaf Collective pilot (after pick up)

Source credit: Leaf Collective 2021 Participant

“We have been collecting leaves over the past few weeks for our gardens and for a friend in Tuggeranong to compost. The autumn has been beautiful, but it has been good to collect the leaves before they wash into the drains.”

It is only when they are left to go down drains that leaves are litter.

When collected for composting or placed in a green bin, a leaf is a valuable carbon resource contributing to soil health. Not only can we re-write our own stories we can turn the leaves at risk of turning villains into heroes or heroines!

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