Established in 1996, National Tree Day is Australia's largest community tree planting event and encourages people to engage in activities that benefit the environment.

This year's National Tree Day will be held on July 31 as organisers seek to plant a million trees, shrubs and grasses to support Australia's natural ecosystem.

Since its inception, the day has been organized by Planet Ark, a not-for-profit environmental organisation who look to engage with the community to help reduce their collective impact on the planet.

Planet Ark Co-CEO and Executive Director Rebecca Gilling said National Tree Day is an opportunity for Australians to engage with nature.

"The program is a call to action for all Australians to venture outdoors, get their hands dirty and give back to their community," she said.

This year's campaign will aim to plant a million trees. Ms Gilling said the tree planting not only helps protect our natural environment but also helps to fight the effects of climate change.

"Trees are truly the lungs of the planet, giving us fresh clean air, storing carbon, providing shade and habitat for wildlife," she said.

"Engaging with nature through tree planting also helps foster our own connection with nature, making it more likely that we work together to conserve it."

Ms Gilling said Planet Ark launched the National Tree Day program to help people connect with nature and the health benefits nature provides.

"The benefits of trees are multifaceted, bringing direct health advantages in terms of urban cooling, shade cover, air filtration and providing spaces for exercise as well as more indirect benefits such as lowering stress and depression, which have consequent benefits in terms of reducing rates of disease," he said.

"Studies show time in green spaces boosted wellbeing during lockdown, supporting Planet Ark's previous research findings on nature's mood, health and productivity boosting effects."

Australians have been encouraged to get involved this July by either planting trees in their own backyards or going online and finding a local National Tree Day site to volunteer with.