Pastoral Land Use

Pastoralism

Fig 1. Generalised land tenure of the NT - land under pastoral leasehold (green), Aboriginal freehold (yellow) and conservation reserve (red).

Background

Pastoralism is one of the major land uses in the Northern Territory, with approximately 55% of the land area used for grazing stock (pastoral leases plus some Aboriginal land). The pastoral industry is generally based on grazing cattle on native pastures, although introduced pastures are used in small areas. Early attempts to graze sheep were unsuccessful because of climatic and other problems, and buffalo are farmed in small areas of the northern floodplains. The production value of the pastoral industry in the Northern Territory was c. $190 million in 2000. This is significantly less than earnings from mining and tourism, but pastoralism makes an important contribution to regional economies and is a part of the history and current social fabric of the Northern Territory.

Pastoral landuse spread through most suitable areas of the Northern Territory during the 1870s-1890s. The industry is now primarily based on breeding and turning off young store cattle for live export or fattening elsewhere in Australia. Property and paddock sizes are generally very large, and carrying capacities of the native pastures much lower than in the intensively farmed regions of southern Australia. There is substantial regional variation in industry structure related to climate, pasture type, property size, ownership, infrastructure development, production systems and land management issues. More detailed information about the pastoral industry is available from the websites of the Department of Business, Economic and Regional Development (DBERD), the Tropical Savannas CRC and CSIRO Centre for Arid Zone Research.

Impacts of pastoral use

Pastoral landuse has had substantial impacts on the ecology of many areas of the Northern Territory. In part, this is because Australian environments did not evolve with high densities of large, hard-hoofed herbivores, so the effects of the introduction of stock were relatively severe. A combination of highly variable climate and relatively low fertility in many areas also means that pastoral use requires very careful management. Some of the most severe impacts were probably associated with the initial arrival of stock into these ecosystems (accompanied by feral animals and possibly new diseases). Stock numbers were initially very high and there was very little fencing - stock were concentrated around natural waters and on pockets of relatively fertile country. The advent of pastoral use is one factor that has been implicated in the decline and/or extinction of many mammal species in the arid region of the Northern Territory.

Pastoral management practices have improved substantially and the level of stock control is now high, particularly since the Brucellosis and Tuberculosis Eradication Campaign (BTEC) in the 1970s. Nonetheless, some ecological effects of pastoral use are still present - including the proliferation of waterpoints; the effects of grazing on plant and animal communities; modification of fire regimes; spread of weeds; and the introduction of exotic pasture species. These effects are briefly summarised here or on linked pages, but it should be remembered that there is often a complex (and poorly understood) relationship between many factors. It is also important to bear in mind that pastoral management can play a significant role in ameliorating many ecological impacts and promoting biodiversity conservation (see below).

There has been a dramatic spread of artificial waterpoints (dams, bores and tanks) through most of the Australian rangelands, including the pastoral regions of the Northern Territory, particularly in the past 50 years. This had the initial aim of opening more country to grazing and, more recently, of evening-out grazing pressure across the landscape. Depending on conditions, cattle will concentrate grazing within 5-10km of water and in most properties there is now very little area more than 10km from a waterpoint. This may have negative implications for biodiversity conservation because there are few or no little-grazed "refuges" within properties for the most grazing-sensitive species (see Biograze 2000 for more information). The proliferation of waterpoints has also assisted the spread of many water-dependent "weedy" native species (such as Red Kangaroo and Galah), feral animals such as cats and some weeds, which may in turn affect on native plant and animal communities.

Grazing by cattle or sheep may cause significant changes to the structure and composition of native vegetation. This habitat alteration in turn has impacts on native fauna because of changes in the availability of resources such as food and shelter. In areas of heavy use, the effects of trampling, localised erosion and nutrient concentration (through urine and faeces) may also be important. The impacts of grazing on vegetation arise because of selective grazing by stock (where "preferred" species are selected and may be eaten out) and differential sensitivity to grazing between plant species. A typical response to heavy grazing is a decrease in the frequency and cover of palatable perennial species and an increase in unpalatable perennials or annual species. Prolonged overgrazing may result in the removal of most perennial grass species and a dominance of annuals, making the area susceptible to drought and erosion. Changes in the structure and composition of the ground layer due to grazing may be temporary and readily reversed following good rainfall, or by reduction in grazing pressure. However, prolonged overgrazing may result in a transition to another vegetation 'state', from which a return to the desired land condition is difficult to achieve. There may also be gross changes in vegetation structure in some pastoral areas due to tree-clearing, increased density of native trees and shrubs ("woody thickening") or the proliferation of weeds, and this is likely to have substantial effects on biodiversity in the affected area.

An important concept is that of "increaser species" (which become more abundant under heavy grazing) and "decreaser species" (which decline under heavy grazing). Increaser and decreaser responses are well known for many pasture plants. Recent research by CSIRO (in the arid zone) and PWSNT (in the Mitchell grasslands) has shown that increaser and decreaser responses are found in most groups of plants and animals (eg. reptiles, birds, ants) in a wide range of environments. Of most concern for conservation management are the decreaser species, which may make up about one quarter of all species in a group. If all the suitable habitat in a region is subject to moderate to heavy grazing pressure, then the most sensitive decreaser species may disappear. One problem in identifying the decreaser species in a particular habitat is that there is often few or no "reference areas" that have never been grazed.

The advent of pastoral use in many regions has been accompanied by changes in the prevailing fire regimes, which in turn may affect native plant or animal species. In some pastoral areas fire is deliberately suppressed in order to maintain feed levels, while in other areas the frequency of burning may have increased. This change has been exacerbated in many pastoral regions where Aboriginal people can no longer carry out traditional burning practices. However, fire is increasingly being adopted as a management tool by pastoralists to improve pasture quality, control grazing distribution and suppress weeds or woody plants.

Pastoral regions of the Northern Territory contain many weed species that pose significant environmental threats. While pastoral use may assist the further spread of weeds, pastoralists also play an important role in weed management. An issue of particular conservation concern is the introduction and spread of exotic pastures. Experience has shown that many introduced pastures have become serious environmental weeds, or have the potential to do so, and pose significant threats to biodiversity. The control of feral herbivores (such as donkeys, horses, rabbits and feral cattle) is a significant issue for both conservation and pastoral management, as these species add significantly to the total grazing pressure. Feral carnivores such as cats and foxes are a severe threat to biodiversity across all land tenures.

Integrating biodiversity conservation with pastoral management

While the major goal of pastoral land management is the production of cattle in a sustainable fashion, a secondary goal is the maintenance of biodiversity values within the pastoral estate ("off-reserve conservation"). This is particularly important in the Northern Territory, where pastoral use extends over such large areas. Many of the Territory's environments occur only or primarily on pastoral land, and many native plant and animal species are dependent on habitats under pastoral tenure. Fortunately, much of this habitat remains relatively intact over large areas, rather than reduced to the isolated fragments found in intensively farmed southern Australia.

Many of the goals of sustainable pastoral management will also help to maintain biodiversity values, including the maintenance of a good cover of native perennial grasses and control of weeds and feral animals. However, additional management actions may be required to protect particularly important habits or species. This could include fencing off sensitive areas such as wetlands or breeding colonies, and leaving selected areas of a property with little or no grazing pressure in order to protect decreaser species. Landholders may also enter into management agreements with the Parks & Wildlife Service in order to protect certain areas. Pastoral managers can therefore play a very important stewardship role in maintaining landscape health over large areas of country. These conservation goals will be best achieved in the context of regional planning that balances the requirements of production and conservation. Current research by PWSNT and the Tropical Savannas Cooperative Research Centre is examining the most effective methods for managing and monitoring biodiversity on pastoral lands.

Threats to Wildlife

Pastoral Land Use

Pastoralism

Background

Impacts of pastoral use

Integrating biodiversity conservation with pastoral management

Further reading