Oh dear, where did this year go? Where did this month go? I thought I should put something up today as Consumas day is fast approaching, quickly to be followed by the end of the year. This may be my last chance to get my stats up for the year! Only kidding, there are a few things that have been on my mind lately, so I thought I would put them in one big post and get them all out there.
The main thing I want to talk about is “Native Plants”. I have had many people tell me “I have no room for vegies in my garden, I only grow natives”. There are a number of reasons for this, native plants often have a lower water requirement than their thirsty exotic cousins, and may be lower maintenance in general. They also have particular value in preventing erosion on steep sites, and along rivers and creeks, where other plants may not be established, and access is limited. They can provide habitat and food for native birds, reptiles, amphibians and insects, all of which may be predators of garden pests. But many of them tend to suppress the growth of other plants growing underneath or around them, and there are other issues with including them in a mixed garden. But what do people mean when they talk about gardening with “Natives” in Australia?
This Eucalypt was planted too close to this block of flats, and is really too big for the garden it's in. Note that it has already lost several large branches.
Australia was isolated from the rest of the world for millions of years, resulting in a hugely different ecology than that which may be found elsewhere, especially that of the Northern Hemisphere. Australia avoided the glacial coverage of the last Ice Ages which affected most of Europe and North America, and so the ecosystems here are much older than theirs. Lack of competition from more recently evolved species means that plants and animals survived here that are not present anywhere else in the world.
Take, for example, the monotremes. Echidnas and platypus are the last remnants of a transitional phase between reptiles and mammals. Their young hatch from eggs, yet they have fur, and the mothers feed them with milk. The rest of the marsupials are also unknown in the rest of the world. They have been replaced by placental mammals for the most part, who carry their young for much longer rather than having them develop in a pouch. The plants are equally as “unusual”, certainly when viewed, as they were, from a European scientific perspective by white colonists.
The Australian vegetation often relies on fire for its survival. The fire cycle varies throughout the country, but is present in most areas, except, notably, rainforests. The main difference between regions is the period between fires, which to a great degree influences what kind of vegetation cover is present. The longer the gap between fires, the larger the trees tend to be, and the more closed their canopy. The Eucalypts are often the tallest, most dominant species in fire dependent systems, and they are also among the most flammable, the oils in their leaves being especially liable to burn. In other areas, Melaleucas or Tea Trees may dominate, and they also produce flammable oils. This feature alone makes them not generally undesirable for planting near houses, not to mention their often excessive size at maturity.
But lets look more closely at what “native” really means. In Australia there are estimated to be over 15,000 endemic plant species. They grow in range of conditions from tropical to sub-Antarctic, from coastal areas to mountain tops, on soils ranging from sand to the heaviest clay, and every combination of these. A plant indigenous to the Swan River in Perth is as far from home in Cooma, New South Wales as a Welshman in Siberia. Planting of Australian plants outside their native range can also disrupt migration patterns of birds, in particular. Certain bird species feed on nectar for one part of the year, and migrate to other areas when the nectar runs out to feed on insects and other protein rich food sources. If nectar is available all year, the birds do not migrate, and their health or that of their offspring may be affected. So native doesn’t tell us all that much. Plants that were originally found in a particular area prior to European settlement should be referred to as “Local Indigenous” plants.
Local indigenous plants are the plants that are unarguably best adapted to the area in which they were originally found. But things change. The soil, in particular, will be unlikely to have remained unaltered by the European influence over the last 200 years. Most residential areas have been developed on what was once farmland, meaning the soil is disturbed physically, due to cultivation, and chemically, as fertilisers and additives would have been added to increase productivity. The pH and salinity levels may also have changed. In short, putting local indigenous plants back in the same place may not be to their advantage under such conditions.
There is an argument for providing habitat for native fauna, though anyone who has tried to grow food when there are possums around will know that our food is just as tasty to them as it is to us. Another major issue is fragmentation. Small, isolated patches of native vegetation are difficult to maintain, and provide little habitat individually for the animals, birds and insects they may attract. The actual attraction itself may be dangerous for animals, encouraging them to cross roads, for example, in order to migrate from one patch to the next. Moving from one yard to another will also place them in the vicinity of domestic dogs and cats, who are probably not well versed in conservation issues, and could see small animals and birds as play things, or as threats. Large, continuous patches of vegetation are best for conservation purposes, where animals can migrate freely throughout the range.
Swamp paperbark is often used as a street tree, its natural tolerance of low oxygen levels in the root zone make it ideal for growing in heavily paved or high traffic areas.
Lastly, I can’t help but think about the unseen impact of purely aesthetic gardens in towns and cities. It basically means that all the requirements of the settlements must come from somewhere else. Rural areas are cleared, and the local environment around productive farm land is damaged by the processes. Not taking responsibility for needs in the same location as we live means just displacing the loss of indigenous vegetation elsewhere. It is very much a case of “Out of sight, our of mind” in that we lower the aesthetic and conservation values of the places our food comes from, while surrounding ourselves with whatever attractive plants we prefer. Some Australian plants have specific uses in cities and towns, like the Swamp Paperbark (Melaleuca ericifolia) as a street tree. But few have been selected or bred specifically for food to the extent that most exotic agricultural and horticultural crops have.
The way I look at it, people should have the plants they need, mostly food plants, close to where they live. I don’t believe productive gardens need necessarily be unattractive. Personally I can think of few more delightful ideas than lounging in a garden full of food in any season throughout the year. If we move away from the strict rows and spacing that are taught as the “proper” way to grow, this idea is easier to imagine. For the most part, the arrangement of plants in straight rows a certain distance apart from each other is of benefit to large scale operations, for planting, spraying and harvesting often using machinery. On a small scale, such limitations are reduced or removed. Sure, if you plant four Tomatoes close together, each plant produces less tomatoes, or smaller tomatoes. But what household needs more than a few tomatoes a day? And the more individual plants you have in an area, the more chance of staving of disease. Even on a small backyard scale, genetic diversity makes for a more robust system.
If you really want to plant natives, make sure they are the species that actually grew originally in your area. Make sure the seed was collected from as near as possible to the site where they are to grow. And unless there is some major issue with the site, such as soil toxicity, try growing some of your own food as well, so there’s less pressure on places you may never even visit. Hopefully there’s a few points to ponder over the Festive break. My best wishes to all readers for the new year, and make a resolution to get stuck into that garden!
