Vital for human survival: trees

Vital for human survival: trees

Dr Rosalie Schultz, PHAA Environment and Ecology Special Interest Group member


“Imagine if trees gave off Wifi signals. We would be planting so many trees and we’d probably save the planet too. Too bad they only produce the oxygen we breathe.”

 (Mudabbir Khalid in the Huffington Post, 2014).


Trees produce more than just oxygen. They’re vital for human survival, and according to a World Wide Fund for Nature (WWF) survey, most people want to know more about the health and well-being benefits of trees. So WWF collaborated with Doctors for the Environment Australia (DEA) to produce Trees – the forgotten heroes for our health to describe what is known about how trees and forests boost human health and wellbeing. Here I summarise the report, as it reflects my love of trees.

We can experience trees through all our senses if we see, hear, feel, smell and even taste them. Ancient giants with limbs stretching skywards to a cool green canopy, maybe with a minty, woody, fresh, or camphorous smell, and gentle breezes rustling through leaves.

Yet as more of us live in cities, we have less experiences of the beauty of trees. Trees are being destroyed to make way for development. In this age of competing priorities, it may be useful to quantify the life-enhancing effects of trees – which we already have an intuitive awareness of.


Trees can boost mental health

Being in nature, and with trees and other vegetation can help reduce stress and lessen depression and anxiety. According to research discussed in the WWF/DEA report, living in a neighbourhood with higher tree canopy cover is associated with reduced odds of developing psychological distress. With half of all Australians suffering from a mental health condition over their lifetimes, there are potentially millions of people whose lives could be improved by planting and protecting trees. For some, forest bathing, a traditional Japanese practice of walking slowing through a forest can lower stress, improve sleep, and reduce anxiety and depression.

Climate change is also contributing to anxiety and depression, and as our planet warms, trees have increasing importance. Trees provide shade which cools surfaces and transpire water which cools the air. Thus, trees reduce the ‘heat island’ effect which amplifies warming in cities. The WWF/ DEA report confirms that in a city heat wave, tree cover can reduce heatstroke, ambulance call outs, and premature deaths.


Trees can cleanse the air

Trees improve health and wellbeing by cleansing the air we breathe. They absorb gaseous air pollutants including sulphur dioxide and nitrogen dioxide from motor vehicle exhaust and other fossil fuel combustion. They also trap damaging fine particles of pollution that can penetrate deep into our lungs and enter the bloodstream. Air pollution is a risk factor for heart disease, asthma and other lung disease, stroke, lung cancer, and diabetes, in addition to having adverse effects on pregnant women and young children.


Trees can promote health and development in children

Shady trees can reduce sun exposure, protecting us from UV damage to eyes and skin, and reducing skin cancer risk. Australians of all ages need to avoid unsafe UV exposure, but this is especially important for children because of the life-time risk of melanoma from childhood sunburn.

Besides supplying protective shade, trees can help promote healthy child development. They enable kids to build spatial awareness, strength, self-confidence, and creativity. Children love to climb trees, although this opportunity has fallen in recent generations.  Safe and supportive places to play outside and climb trees should be prioritised because there are so many benefits of outdoor play. Trees encourage people of all ages to exercise and relax.


Forests provide unique benefits

Trees are the defining species of many forest ecosystems, which have further importance for our health and wellbeing. Forests collect, store and purify rainwater, providing a filter that releases high quality drinking water into reservoirs that are the water source for cities. Natural clarification reduces the need for chemical and physical treatment of water. Trees can also reduce flooding by holding water, and may reduce landslides by stabilising soil.

Forests provide habitat for wildlife. Less natural forest can lead to more interactions between humans and animals with infections, resulting in more opportunities for diseases to spread from animals to people. To protect and promote health and wellbeing at home and internationally, Australia needs to end de-forestation and restore and regenerate forests that have been lost.

Whether or not we need high technological, expensive and unproven options such as carbon capture and storage to mitigate climate change, we must increase tree growth and forest cover. Australia’s reputation as a deforestation hotspot reflects our settler history of exploiting the land and its people.


Aboriginal and Torres Strait Islander Peoples

Aboriginal and Torres Strait Islander Peoples may hold distinctive relationships with trees. Trees hold the life force and are interconnected with human communities. They connect people to Country and lore, which is critical for health and well-being.

Cultural knowledge of trees sustains First Nations Peoples, continuing their connection to Country over many millennia. Particular trees “have great spiritual value, holding ancestor stories, marking sites of ceremony, birthing and burials and much more”. The DEA/WWF report also said that trees can “serve as a source of identity for Aboriginal and Torres Strait Islander Peoples.”

I congratulate WWF and DEA for this beautiful, comprehensive, and well-referenced report, and thank the authors for providing me with understanding and even more pleasure of trees.


Image credit: Rosalie Schultz, Worlds End, near Burra, SA

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