Revegetation Strategy - Townsville State of the Environment Report

Townsville City Council Draft Revegetation Strategy
Plant arrangement may be determined by maintenance considerations. For example, if a
tractor slasher is to be used for mowing grass between trees, relatively straight rows of trees
may be required. Irrigation lines will also dictate plant positions to a fair extent. A random
arrangement produces a more natural appearance.
Planting trees in clusters is an effective compromise between these extremes - a slasher can be
used between clumps, and manual weeding effort, watering, and mulch can be concentrated
within each clump. Slashed grass can also be used for mulch, reducing one ongoing
maintenance cost.
Planting time will be influenced by availability of materials and people. Best times for
optimum survival are probably during the wet season (low water stress, assuming a good
wet!) or mid winter (low heat stress), but good results can be achieved at other times if good
preparation and follow up maintenance is practised.
5. Site preparation.
Physical:
Some soils in this region are relatively acidic (pH lower than 5.5), and could benefit from the
addition of lime or dolomite.
Lime, dolomite and gypsum are also useful for breaking up heavy clay soils, and improving
soil structure and drainage. Rates of 10 tonnes/hectare (1 kg/m 2 ) are recommended. Another
technique (often used in conjunction with gypsum) for breaking up compacted and heavy
soils is deep ripping (0.4 - 1 m depth), using a tractor with a suitable implement. Ripping also
reduces competition from nearby trees by severing their surface feeder roots. In sloping
ground, rips should be made following the contours, to improve moisture retention and
minimise erosion.
In boggy areas, mounds of soil may be constructed to reduce waterlogging. However, this is a
very labour intensive and costly exercise, and should be considered only in exceptional
circumstances (eg a particular feature tree).
On sloping ground, swales dug following the contour of the slope improve moisture retention,
and reduce erosion potential. Steeper slopes and eroded creek banks may require more
extensive earthworks, such as construction of retaining walls or gabions (rock filled wire
baskets placed over eroded surfaces).
Biological:
Weed control is a major factor contributing to the success of any revegetation project, both
before planting and during subsequent maintenance. Weeds may adversely impact on
plantings by various means, such as competing for water, nutrients and light, increasing fire
risk, producing toxic (allelopathic) chemicals, or strangling. Weeds are encouraged by
disturbance (eg fire, feral animals, intensive site preparation), and high levels of nutrients,
moisture and light - conditions often produced during the process of revegetation! A highly
successful, although labour intensive, method of natural bush regeneration, the Bradley
method, utilises minimum disturbance methods of weed removal to allow natural regeneration
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