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Using indigenous plants | LC0111 |
Kathryn Purnell, Frankston
June, 2001 |  |
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More people are planting and direct-seeding indigenous trees, shrubs, and understorey plants in recognition of their value to land and farm management. Indigenous plants are the original native plants occurring naturally in a specific area, and there are many benefits in using them to revegetate the local landscape.
Benefits of using indigenous plants
Locally evolved for survival
The indigenous plants of an area have evolved over a long period of time. They are well adapted to local conditions such as climate (especially rainfall) and the area’s topography and soils.
Genetic variations
Many native plants occur across a broad geographic range. However, within that range, different populations of a particular species may change slightly to become specifically adapted to local conditions and individual habitats. Different populations containing local genetic variations are called provenances. It is important to preserve these different provenances, as each provenance is unique.
Besides more obvious physical differences (such as varying leaf shape and size), they may contain genetic material whose benefits have not yet been quantified or even discovered.
For example, some provenances may cope better with future climate change, or changes brought about by past and present farming practices, such as rising watertables and increasing salinity. Others may have important properties useful in new medicines.
Local identity
Locally indigenous plants are unique to their area, and define its visual character. For example, the forest red gum woodlands of the Gippsland Plains are part of the region’s local identity, and are found nowhere else in Victoria.
Ecological balance
Indigenous plants have evolved as part of the entire biological population of an area. As a result there is a strong interdependence both between the plant themselves (including fungi and lichens), and with the local native animals, insects, and micro-organisms with which they have evolved. All components of a healthy ecosystem are in ecological balance with each other.
Wildlife habitat
Animals need a healthy and diverse range of local plants for both food and shelter. However, they vary enormously in their habitat requirements - some animals aren’t too particular, but others can have very specific requirements, and must have access to particular indigenous plants in order to survive.
Natural regeneration
Being locally evolved, indigenous plants are well suited to unassisted regeneration, and reproduce either by seed or by suckering. This ability is particularly important after an area has been burnt by fire. In fact, an appropriate fire regime can be important in maintaining the health of remnant bush and in stimulating natural regeneration. Even without fire, many indigenous plants will regenerate easily and shouldn’t need replanting (though they may still need some assistance, such as weed control or controlled soil disturbance, and protection from excessive grazing).
Persistence
The vagaries of the Australian climate put a lot of stress on vegetation survival. However, having evolved locally, indigenous plants have developed mechanisms which usually enable them to survive where non-local plants may not. An example is the ability of many indigenous perennial grasses to remain active into summer, providing on-going ground cover and soil protection, and also enabling them to quickly respond to intermittent summer rainfall.
Pest and disease balance
The diversity of a balanced, indigenous ecosystem makes it relatively resistant to pest and disease outbreaks. However, where the coverage and diversity of indigenous plants is reduced, resulting imbalances can make the local ecosystem more susceptible to attack. A significant example in East Gippsland is the dieback occurring in remnants of forest red gum (Eucalyptus tereticornis) woodland.
Research has shown dieback to be a symptom of an ecosystem under severe stress and imbalance, and the contributing factors are complex and often interrelated. Factors causing dieback in local woodland remnants include a loss of understorey and wildlife habitat, modified fire regimes, soil deterioration, and altered hydrology.
An obvious symptom of these stresses is the marked defoliation of forest red gums across the East Gippsland Plains. A general decrease in understorey habitat brought about by vegetation clearance and/ or grazing has led to a decrease in natural predators (eg. sugar gliders, birds and bats) and a subsequent increase in numbers of leaf-eating insects (eg. Christmas beetles).
Figure 1. Christmas beetles can have devastating effects on eucalypt foliage, but they provide a tasty meal for local sugar gliders.
Whether protecting and regenerating existing remnant vegetation or establishing new areas, this example illustrates the importance of ensuring that all vegetation layers of an indigenous plant community are present.
These layers (the native grasses and ground covers, as well as the shrubs, and small and larger trees) each form an important part of a balanced and healthy plant community.
Ensuring the presence of suitable habitat for the animal and insect populations with which the plants evolved will help ensure the health and ecological balance of that vegetation.
Weed control
Weed management is fundamental to the success of revegetation projects. Weeds are undesired plants (native or otherwise) which are able to colonise an area by outgrowing competitors and spreading rapidly. Weeds are often more vigorous in growth than indigenous species because they are no longer in association with other plants and animals that would, in a natural and balanced system, have controlled their growth - their natural biological controls. Their spread is often assisted by altering the cover and diversity of remnant indigenous vegetation through heavy grazing, ground disturbance or clearing.
Indigenous plants have an important role to play in weed control, where the solution is not just to kill the weeds, but also to fill their niche with desirable plants in balance with the local environment.
Potential problems
Altered conditions
Where the land has been significantly altered through different management practices or by various forms of land degradation, it may be difficult or in some conditions no longer possible, to re-establish indigenous vegetation.
Unsuitable conditions may exist where:
- soil erosion, compaction, acidification, salt accumulation, or induced waterlogging have significantly altered soil properties;
- regular applications of fertilisers or the manuring of paddocks by stock have significantly raised nutrient levels; or
- areas have been affected by soil borne plant diseases, such as cinnamon fungus.
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In these situations, it is sometimes necessary to introduce plants from elsewhere. In preference, look within the local region for naturally vegetated sites with similar climate and conditions to find suitable species. Otherwise, look for plants from elsewhere in Australia (though preferably as close as possible) that will tolerate your site conditions. However, when considering introducing plants form other regions, always check that the plant is not known to be an environmental weed.
Conclusion
The many values of indigenous vegetation are often overlooked, and considerable benefits can be gained by integrating these values into sustainable land management.
There is also an urgent need to encourage protection and management of remnant plant communities, particularly on private land.
Many plant communities are still poorly represented, and require both the regeneration of degraded remnants and the creation of new habitat within their original range. This will in turn provide more secure habitat for the wide range of indigenous plant and animal species that evolved as part of those communities, and in the longer term, the basis for a healthier, sustainable environment.
Further information
Contact your local office of the Department of Natural Resources and Environment, phone: 136186.
References
Local plant identification references
Fitzgerald, G. & Owen, R. (1996). Revegetation Field Guide for The Mitchell River Catchment. Mitchell River Management Board, Bairnsdale (available from NRE Bairnsdale, or the East Gippsland Catchment Management Authority).
Costermans, L. (1998). Native Trees and Shrubs of South-Eastern Australia. Lansdowne Publishing Pty. Ltd., Sydney
Acknowledgments
Illustration of Christmas beetles reproduced form Gullan, P.J. & Cranston, P.S. (1994) The Insects: An Outline of Entomology. Chapman & Hall, London.
Compiled and edited by Kathryn Purnell, East Gippsland Regional Facilitator, Greening Australia Victoria, with special thanks to Dale Tonkinson, Greening Australia Victoria’s biologist. February 1999.
This note replaces note number TG0010.
The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
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