Bush Care and Regeneration
Maintaining healthy bushland remnants is of fundamental importance to maintaining diverse bird communities in cities. This is because they are reservoirs of biodiversity that generate many of the young birds (and other animals) that disperse out into surrounding urban gardens. Unfortunately, remnant bushland is adversely affected by disturbances coming from developed areas.
Garden waste and weeds
In the past, garden waste was often dumped in bushland remnants, leading to colonization by weeds. Some of these weeds are now well established. As well as direct dumping of weeds, urban bushland is constantly bombarded with seeds from urban water runoff and in the droppings of birds, particularly from big berry consumers such as the Pied Currawong. Many of the berries they eat come from weeds, but they also consume the berries of garden ornamentals. Plants that are desired by gardeners become 'environmental weeds' when they escape into urban bushland. Planting local natives is the best way of avoiding your garden plants becoming environmental weeds, but other responsible approaches include the use of sterile hybrids and non-invasive species.
Weed with care!
Many volunteers are now donating large amounts of their time to weeding and restoring bushland remnants and it is a laborious business. In many remnants, weeds such as lantana have replaced the native understorey. These weeds are now important habitat for small birds as they now offer the only dense shelter sites. Removing these weeds quickly therefore destroys the habitat for small birds, which is one of the reasons we value remnant bushland. Best-practice bush-care requires the gradual removal of weeds, working from the areas of lowest to highest weed density. This means that native plants have the chance to re-establish a dense understorey before the thickest patches of weeds are removed. Well-intentioned, but rapid removal of weed thickets, without concurrent re-establishment of understorey plants, is a major threat to the survival of small birds in urban environments.
Principles of bush regeneration
In Sydney, Bushcare programs involve up to 6000 regular volunteers undertaking bush regeneration practices to gradually 'bring back the bush'. Key principles are:
- Retain: Conserve existing natural areas as a first priority
- Regenerate: Assist the bush to restore itself by not clearing weeds too quickly, allowing time to wait and see what plants may appear from the stored seed in the soil or be introduced by native fauna, especially birds, and considering methods like fire or light disturbance of topsoil to encourage native plants to return. Weeds are removed at appropriate times eg before setting seed, and large woody weeds that may be helping to reduce soil erosion may be poisoned but left standing to continue holding the soil or creek bank.
- Replant last: Planting should only be considered after a site's natural ability to recover has been assessed as poor, such as where the natural soils have been removed or extensively disturbed. Only plants grown from locally collected seed (provenance) seed are used in revegetation programs.
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