Do gardeners live longer and have the lowest carbon footprint in Australia?

Is gardening the best hobby to reach 100 not out?

All the studies on longevity indicate that gardening, and particularly growing your own food, is highly beneficial and contributes to both a less stressful and longer life. Gardeners on islands such as Okinawa in Japan and Sardinia in Italy, continually report that they have the longest life expectancy. Apart from growing their own food, most experts believe that the Japanese and Mediterranean diets, being largely vegetarian and containing fish, also have lower levels of fat and sugar, which are essential elements that lead to longer life expectancy.

So why is it that gardeners are the most likely societal group to reach the age of 100? Is it because daily gardening lowers the risk of dementia by 36%? Could it be that it reconnects us to wilderness, which is increasingly difficult when 86% of us now live in cities because of the huge population increases in the last 50 years?

Biodiversity

Do gardeners have the lowest carbon footprint in Australia and do we lead in solving climate change? By planting trees, shrubs, perennials and annuals in even the tiniest backyard, gardeners create far greater biodiversity of species than any other occupier of land, other than wilderness.

Count up the number of plants in a tiny backyard and compare that with the number of species grown:

• In a fruit orchard.
• On an animal grazing property.
• On farms with crops of wheat, canola, corn and sugar cane.
• In a tree plantation of eucalypts or pine trees.

All these land occupiers have, over the centuries, destroyed the wilderness – monoculture crops dominate land that was once thriving with biodiversity.

Planting trees and shrubs

All of us must change our behaviour, which is the hardest thing to do. We need to cut emissions in transport, heating, cooling and travelling to help us succeed with our energy sources from renewables, but it’s also vital that our food is grown sustainably – free of artificial fertilisers, weedicides and insecticides.

If every person planted 160 trees over the next 10 years we would bring so much carbon back to earth that we would gain enough respite to tackle the challenges of cutting emissions. Rates vary from species to species but, in general, around 50% of a tree’s weight (above ground and excluding roots and organic matter) is stored carbon, and as the tree continues to grow, so does its carbon storage capacity.

• A small mature tree (e.g. lemon, apple) weighs about 300kg (150kg of carbon).
• A very large mature tree (e.g. elm, plane, oak, red gum, Moreton Bay fig ) weighs about 3.2 tonnes (1.6T of carbon).
• The world’s largest tree by weight of carbon is a Sequoiadendron giganteum known as ‘General Sherman’ (aged 2,020 years). At 84m tall, it weighs 714T and is easily the most massive living thing on the planet, although other Californian redwoods long removed would have vied for the title of largest tree. Giant Sequoias have a carbon storage rate of 55% – General Sherman stores 392T of carbon and has removed 1,439T of carbon from the atmosphere during its lifetime.

We have already cut down 3 trillion trees or about 50% of our global forest, which is disastrous – we now need those trees to absorb 66% of the carbon in our atmosphere to keep the temperature rise within 1.5°C.

Most gardeners compost their green waste and leave their grass clippings on the lawn, continuing the recycling of organic matter and replacing artificial fertilisers and chemicals. When we grow our own food our carbon footprint is reduced by 25% (that’s about 4 tonnes of CO2 less than the non-gardening population).

It’s fair to say we gardeners are doing our bit – but by planting more trees we can have a bigger impact still.