This Sunday was National Tree Day, an annual event begun in 1996, coordinated by Planet Ark, where communities across the country organise plantings of native trees and shrubs to improve their local environment. Over the past 22 years, more than 3.8 million people have planted 24 million trees. In my town, people gathered on the village green to plant a blackbutt sapling to join the three white mahogany trees (Eucalyptus acmenoides) planted at the three preceding Tree Days. These white mahogany saplings had been grown from the seed of a majestic old specimen that was very sadly felled a few years ago to build a block of apartments; and a hedge of the beautiful foliaged lilly pilly cultivar 'Cascade' begun last year was extended along the edge of the park.
National Tree Day is laudable for so many reasons. As suburbs undergo rampant development to cram in apartments and townhouses, more trees than ever are being removed, creating 'urban heat islands'. As well as beautifying the landscape, a canopy of trees is the most effective way of cooling our suburbs, especially during the recent long, hot, dry summers we have been experiencing. Trees also improve air quality by absorbing polluting gases and odours, and filtering air particles. Trees, especially local indigenous species, provide habitat for wildlife and can act as a corridor to connect remnant bushland areas in suburbia. At today's event, local residents were buoyed to hear from the mayor that after losing 15,000 trees a year, Hornsby Council has now decided to plant 25,000 new trees along streets and in parks by September 2020: fabulous news indeed.
In country areas, planting trees can help reduce soil erosion and salinity, lessen stormwater runoff, and provide shade for animals. All trees sequester carbon: locking up large amounts of carbon in their wood. It has been estimated that one-half of the weight of dried wood is carbon. Thus trees help to slow the increase of carbon dioxide that is trapping heat in the Earth's atmosphere. The ecosystem on farms where once trees were cut down to create bare paddocks can be totally transformed by mass tree planting.
National Tree Day actively promotes the inclusion of children in its activities, giving an opportunity for young people to understand and appreciate the importance of trees, not only for all the environmental reasons, but also for the psychological and physical health benefits trees have for people - many studies have shown that people are healthier and happier when they have trees around them!
In our own gardens, I feel we need at least one tree to give a sense of scale, structure and height, as well as a feeling of solidity and permanence. A tree can provide privacy and a sense of shelter to the garden and the house itself. It can provide shade for the house as well as for garden areas, protecting other plants from extreme heat in summer and frost in winter. In compact gardens, small deciduous trees have lots of offer, providing shade in summer and sunshine in winter. Their leaves are a valuable source of humus and organic matter for the compost heap. They give a strong sense of season to the garden, with leafy green in summer, often brilliant autumn leaves in autumn, an attractive tracery of bare stems in winter and then the excitement of new leaves (and possibly flowers) in spring. Many can be grown in very large pots. Some of my favourite small deciduous trees include Japanese maples, the smaller crepe myrtles and crab apples (Malus species). Amongst evergreen trees, the spectacular grafted red flowering gums (Corymbia ficifolia) can now be obtained in more compact sizes, and I am about to plant one of these as my National Tree Day contribution!
Planting a tree has always seemed to me quite a solemn and momentous event. We are planting something that in all probability will outlive us and become an important feature of the landscape of the future. It is obviously ideal to plant one's tree(s) at the outset of creating a garden, so that they can grow and mature along with the garden. However, this can result in poor choice of specimens if there is not enough knowledge about the characteristics of trees, as in my case, when I planted a sapling of an enormous gum tree in my first garden, which was out of all proportion to the yard. It's wise to seek expert advice in tree choice if you aren't sure, and avoid monsters that will get way too tall; trees whose roots will invade drains and the rest of the garden; those with wide canopies that will shade a lot of the garden; weedy varieties that self-seed prolifically; and those with a short life, which will ultimately prove disappointing.
Even if we don't get round to planting trees until we are middle aged, we can still enjoy watching the progress of a tree maturing over the years. It's amazing how quickly the years go by and what was once a nondescript stick with a few tufts of leaves becomes a sturdy, muscular tree with a distinctive shape and a real presence, fulfilling its destiny as surely as a child growing into an adult. When planting a tree, give it the best possible start by preparing the soil around the spot well and adding plenty of organic matter. Keep it mulched and well watered in its early life, especially during these worryingly dry times.
The allure of the orchid cactus
24 Oct 21
This intriguing epiphytic plant is in bloom now.
Ageing and gardening
17 Oct 21
As one gets older, there is the need to rethink aspects of one's garden.
Painting with coleus
10 Oct 21
Coleus can make wonderful pictures in the garden.
03 Oct 21
Tough and undemanding plants from my parents' garden are favourites in my own.
The value of green spaces
26 Sep 21
Earlier this year, I visited Callan Park in Sydney's inner west.