Invasive Species:
Pressure State Response Indicators

Pressure Pressure is characterised by an increasing density of non-native species (both plant and animal) and a corresponding decrease in the abundance of native plants in pastures and rangelands. A proportion of the invasive plants species may be toxic to livestock and wildlife. Others are of reduced value to livestock. The result is a decrease in the nutritional value of rangelands and natural pastures. In order to combat this, livestock owners and rangeland managers may then be forced to spend considerable sums to first initiate and subsequently maintain control programmes. | Pressure State Response

The global picture is one of a significant mixing of species with unpredictable long term results.

State

State is characterised by the following changes:

- Increase in density of invasive, introduced, plant species;
- Reduction in density of native plant species;
- Reduced biodiversity;
- Reduction in the nutritional value of pastures and rangelands;
- Decrease in livestock production;
- Increase in expenditure on control and eradication programmes.

Response

In most cases invasive plant species reduce the local diversity or abundance of a given population or alter community structure. Removal of these invasive species is often accompanied by a recovery of the biota. However this can be a slow process. Many invasive species have proved impossible to eradicate or at least extremely difficult and costly to eradicate once established.

Thus, stringent measures to avoid undesirable species in introductions are justified both on economic and ecological grounds.

Response is therefore characterised by:

- Legislative measures to limit the introduction of new potentially invasive species;
- Enforcement of these measures;
- Monitoring of the change in plant (and animal) species diversity on rangelands and pastures;
- Introduction and adoption of appropriate control and/or eradication measures;
- Dissemination of information on the importance and impact of invasive species;
- Dissemination o information on appropriate control measures;
- Subsidies and other management incentives designed to facilitate control measures;
- Research into new control and/or eradication measures.

Further Reading

McNeely, J.A., Gadgil, M., Leveque, C., Padoch, C. & Redford, K. 1995. Human Influences on Biodiversity. Pp 711-821 in. Heywood, V.H. & Watson, R.T. Global Biodiversity Assessment. UNEP. Cambridge University Press. ISBN 0-521-56481-6.

> [Livestock & Environment Toolbox Home]