9.1.3. What about understorey?
Most people are aware there’s a big problem with tree decline in rural Australia. We’re often less aware that the decline in understorey species has been even more severe.
Wattles are often the only understorey species we see, but in nature, the understorey can be very diverse. For every three or four tree species on a hectare of natural woodland there can be as many as 30 understorey species.
Include photo of understorey plants - Retief/Crane photo?
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What understorey plants can do for you:
• Shade and shelter — you can use understorey species in planted shelter-belts, along fence lines and along creek lines. Most of them grow rapidly, providing stock with shade and shelter faster than trees. The understorey also shelters young tree seedlings.
• Improve soil fertility — wattles, native peas, casuarinas and some other understorey species fix nitrogen in the soil; understorey species, related micro-organisms and insects such as ants are important in nutrient cycling — getting organic matter back into our poor soils.
• Provide food and shelter for natural pest controllers — many insect-eating birds find shelter and food — such as flower nectar — in understorey species.
• Offer fast erosion control along steep slopes, creeks and drainage lines.
• Help build native vegetation corridors throughout the rural residential landscape for healthy native plant and animal populations.
• Increase the density of insectivorous animals such as bats, flycatchers, wrens, warblers.
• Offer windbreaks to reduce weed seed spread.
• Shade out weed species.
What you can do:
• Conserve existing understorey in areas not dedicated to production and encourage natural regeneration by temporary or permanent fencing. Conserving is always easier than replanting. Some species are hard to establish or will not grow on disturbed sites.
• Alternatively, plant or direct-seed a mixture of understorey species, preferably species adapted to the area. This is particularly good advice when sowing in a paddock or along a waterway where exotics can spread and crowd out natives.
A list of understorey species suitable to this region is provided in the appendices.
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