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20 Jul 2020

Trees – battered and burnt, but resilient.

Trees are amazing things – many are amongst the largest and the oldest living organisms on the planet. Trees are travellers in time, witnessing history around them and containing clues to how our environment has changed over hundreds and in some cases thousands of years. 

Dr Brett Summerell Director Research & Chief Botanist

They moderate our climate, protect and provide habitat for a myriad of creatures and are critically important in cycling nutrients in Earth’s ecosystems. 

If we take a purely human focus, trees are also important in our urban environment, making it less hostile to us and in turn making us less hostile to those whom we share our environment with.

However, this fire season in 2020 has seen devastating impacts on trees and across Australia the whole natural world. The extent of the bushfires has been of a scale that is very difficult to comprehend. 

I keep getting asked: What has an impact on plants has been? Burnt landscapes of immense size, are of course mainly made up of burnt plants – trees and the understorey species that comprise those rich and beautiful ecosystems. How many plants have been killed?

It is difficult to estimate the number of plants impacted by the fire. 

Published tree densities in different types of ecosystems range from 500 – 1,200 trees per hectare. And if we multiply this by the area burnt (10 million hectares and counting) with an assumption that 60% was natural ecosystems this could give 3 – 7.2 billion trees impacted; with just as many understorey species also affected. 

The impact on understorey species is usually much more dramatic, and final, as these species are more likely to be burnt completely. 

We are currently monitoring the recovery of plants in bushfire affects areas across New South Wales – trying to understand what will survive and those species or ecosystems that will not. Our seed collectors are planning to ensure that as many species that are able to produce seeds are collected – leaving behind enough to ensure regeneration – so that we can protect those species for the long term.

We need trees - the most critical thing trees do is store carbon – taking in carbon dioxide during photosynthesis and expelling oxygen for us and all other organisms to breathe. 

There is substantial evidence that the presence of trees and our contact with them, especially in urban neighbourhoods leads to improved mental health outcomes, reduces stress and it is now proven decreases the incidence of crime. Additionally, urban trees mitigate air pollution, reduce storm runoff and water pollution. Via shading tress can also reduce energy consumption in homes and other buildings, especially in hot countries like Australia.

The most critical thing we can do right now is to protect existing trees in all our landscapes whether urban environments, rural landscapes or in the bush. These trees have already trapped huge amounts of greenhouse gases and continue to do so. We all need to be advocates for the preservation of these amazing living organisms that contribute in so many ways to our existence.

Learn more

In this episode of Branch Out you'll discover the amazing fire survival mechanisms of plants, the recovery efforts to save some species from extinction and the potential long-term effects and future outlook of our fire season. Or hear an update from Dr Brett Summerell during a recent visit to the Blue Mountains Botanic Garden Mount Tomah in the video below.

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