| Alpine National Park... | ...or cow paddock? | ||||||||||||||||||
| Alpine Grazing - the impact of cattle grazing on alpine and subalpine plant communities of the Bogong High Plains | |||||||||||||||||||
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| In 1991, seven-year licences were issued to cover all grazing in the Victorian High Country. As part of the licensing process, an Independent Panel, chaired by Dr Philip Opas, QC, was set up to resolve a dispute concerning the conditions of the licences. One of the panel’s findings was that monitoring should be extended, and that the results of this monitoring should be reported during the initial seven year licence period. R.J. Williams, W.A. Papst & C-H. Wahren, from CSIRO and La Trobe University, were commissioned to produce the report, which summarised the findings of a comprehensive body of knowledge on the impact of stock on the plant communities of the Bogong High Plains and on similar plant communities in the Kosciuszko region of NSW. This is an abridged version of that 1997 report. | |||||||||||||||||||
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Historical background
It was the late 19th and early 20th centuries which saw the highest stock numbers. For example, during the summer of the severe 1902-03 drought, 40,000 sheep, in addition to large mobs of cattle and horses, were on the Bogong High Plains. Such heavy grazing, associated with burning off and the occasional bushfire, caused substantial damage to the alpine environment. In many places the soils and vegetation were damaged severely. In some places the soil mantle was stripped entirely, and stony erosion pavements resulted. By the 1940s the degraded condition of the Bogong High Plains was cause for concern. Maisie Fawcett (later Mrs Carr), an ecologist, was appointed by the newly formed Soil Conservation Board in 1941 to assess the effects of cattle grazing in the vegetation of the Bogong High Plains. She and Professor John Turner, from Melbourne University, established a series of reference plots in the mid-1940s, which are maintained to this day, yielding long-term data on grazing impacts (see cover photo). In 1946 the government departments and graziers acted together to modify the land management practices. Sheep, horses and burning off were banned, the length of grazing season limited and cattle numbers held at then current levels. Grazing was withdrawn progressively during the 1950s from the highest ridges and peaks, which were invariably the most degraded. These included Mts Bogong, Feathertop, Loch and Hotham. Stock were removed from within Falls Creek resort in 1981; and excluded from the northern Bogong High Plains, which include the high ridges around Mt Nelse and Mt Bogong in 1991. Currently about 3,300 head of stock (including calves) graze those areas of the Bogong High Plains which are available to graziers from December to April. In the Kosciuszko high country, where mainly sheep were grazed, extensive damage was also apparent in the high altitude areas in the 1940s. In contrast to Victoria, stock have been removed entirely from the high country throughout Kosciuszko National Park. Alpine ecosystems in Australia 'Alpine' is used here to refer to landscapes on the Bogong High Plains above approximately 1,600 m. This includes Snowgum woodlands and the treeless plant communities such as heaths, grasslands, herbfields and wetlands. The treeless communities occupy only about 0.1% of the Australian continent. Alpine soils are extremely low in nutrients, and are easily disturbed. They are highly erodible, both by wind and water and may be subject to frequent frost action. Thus, the nutrient limitations of the soils, and the generally short growing season, dictate that the growth of alpine plants is slow, and that, following severe disturbance, regeneration is also slow. Alpine ecosystems, like all ecosystems, are subject to natural disturbances. These disturbances, which may be locally extensive, include frost, wind, drought, insect attack, and, very occasionally, fire.
Grazing, impacts and land condition – some principles Alpine landscapes on mainland Australia are by and large not subject to grazing by large, native herbivores. Kangaroos, wallabies and wombats are extremely rare in the alpine landscape. Thus, the alpine vegetation of the Bogong High Plains and the Kosciuszko region has not evolved in conjunction with native vertebrate grazers. The introduction of cattle therefore was, and continues to be, a major departure from the native grazing regime of the landscape. Ungulates (hoofed animals) such as sheep and cattle are particularly foreign to the Australian alps, as indeed they are to all Australian native plant communities. Determining impacts Scientific interest in alpine landscapes commenced at about the time of the first explorers and graziers, and there is now a rich literature on ecological processes within alpine landscapes. Much of this scientific effort has been concerned with determining the impacts of grazing, especially in relation to land condition. The overriding principle with respect to land condition in Australian alpine environments is that in the vast majority of alpine plant communities, the cover of native vegetation (either as live plant material, or litter) needs to be as close to 100% as possible. Thus, bare ground should be as close to zero as possible. If bare ground is minimised, then catchment condition (in terms of water, soil and nature conservation) is maximised. The impacts of grazing on the plant communities on the Bogong High Plains have been determined by a number of methods, both by the authors and other researchers who have worked in the Australian alps. The long-term impacts have been assessed by a now extensive series of permanent plots (whereby the vegetation changes on grazed plots can be compared with those on fenced, ungrazed plots).In addition to monitoring the vegetation, detailed studies of the diet and behaviour of cattle were made by Harm van Rees over several seasons on the Bogong High Plains. These gave very clear data on the communities which were most used by cattle, and the species within them which were most frequently grazed. These studies have shown that free-ranging cattle affect alpine plant communities by grazing selectively (e.g. by preferring herbaceous vegetation to shrubby vegetation) and by trampling the vegetation. Thus they can alter species composition, and increase the amount of bare ground. Cattle are also implicated in the spread of noxious and environmental weeds, e.g English Broom in the woodlands on the remote, eastern fringe of the Bogong High Plains, and Soft Rush in many of the wetlands around Rocky Valley.
Grazing impacts on the major communities Grasslands Grasslands occupy 25% of the area of the Bogong High Plains. They typically occur on deeper soils on gentle slopes, which are prone to frost and high winds. None of the grazed sites have the combination of a high cover of the showy herbs such as Celmisia sp. (Silver Snow Daisies) and low amounts of bare ground, which have characterised the Pretty Valley ungrazed plot for at least two decades. The grasslands at Mt Fainter are less diverse and in a more degraded condition than those at other sites. Here, the amount of low quality cover is high (25%), which is twice as much as some of the other grazed sites, and ten times as much as the ungrazed site at Pretty Valley. The taller, palatable, major herbs such as Celmisia and Craspedia sp. (Billy Buttons) are absent. These impacts of grazing are incompatible with the maintenance of catchment protection, soil conservation values and national park/nature conservation values. In all high mountain catchments, runoff is heavily dependent on the density and amount of vegetation cover. Selective grazing has clearly resulted in decreases in the cover of palatable species such as the taller herbs, has degraded the general condition of this plant community, and is preventing its recovery. Heathlands Heathlands occupy some 50% of the Bogong High Plains. Closed heath predominates on the steeper, more sheltered slopes, where soils are shallow and rocky. Open heaths occur on gentle-moderate slopes, often on exposed NW aspects. There are two key issues with respect to grazing in heathlands. The first is the stability and regeneration of the communities, the second is the effects of grazing on shrub cover. In the open heath, the alternation between shrubby phases and grassy phases across the landscape is a consequence of cyclical patterns of regeneration in the two community dominants - Alpine Grevillea and Snow Grass. There have been many claims that the cover of shrubs is reduced by cattle grazing, which in turn reduces the fire risk in the alps. However, such claims are not supported by any of the long-term monitoring studies, nor by a consideration of the behaviour and diet of cattle. As shrubs such as Grevillea, in open heath, age and begin to open out, they are replaced by snow grasses, and disturbance of this grass sward is necessary for a subsequent generation of shrubs to establish as seedlings. This is a common process and has been well-documented over the Bogong High Plains. In closed heathland, cattle have very little impact on shrub cover, as the shrub species present are not palatable, and the dominant shrubs regenerate vegetatively (e.g from stem buds or root stock) following disturbance. Alpine grazing does not reduce blazing by 'controlling' the shrubs.
Wetlands Wetlands - which are mainly bogs or mossbeds - occupy less than 10% of the area of the Bogong High Plains, but they are extremely important hydrologically. They occur where drainage is impeded, and water remains near the soil surface for more than one month per year. The soils of wetlands are peats - highly organic soils, derived from the decay of vegetable matter, with little or no mineral matter. Wetlands are vital to water catchment protection, soil conservation, and maintenance of nature conservation values. They have been listed under the Victorian Flora and Fauna Guarantee Act. Even though wetlands are not a preferred grazing community to cattle, they contain numerous palatable species. Cattle will certainly enter such wetlands to graze, as well as for drinking water, throughout the grazing season. Cattle have dramatic effects on wetlands. The peaty soils are particularly susceptible to trampling, as are the common plants, especially Sphagnum Moss. Cattle entering mossbeds to drink cause breakdown of the sphagnum and peat, lowering of the water table and consequent drying out. This results in fragmentation of the heath, widening of channels and increasing runoff, all of which cause vegetation to be stripped, leaving silty and stony pavements. Few grazed wetlands on the Bogong High Plains are in good condition, and those on Mount Fainter are highly degraded. Many silty and stony pavements have apparently been induced by grazing, and regeneration on these pavements is being inhibited by cattle. Wetland condition will not improve if grazing continues.
Snow Patch Herbfields Herbfields which occur on steep slopes where snow persists well into the growing season ('snow-patch herbfields') occupy less than one per cent of the landscape of the Bogong High Plains. They are thus one of the rarest and most fragile plant communities in Australia. They are listed under the Flora and Fauna Guarantee Act. Snow patch herbfields are particularly sensitive to cattle activity, due to the high concentrations of palatable species, the steep slopes on which they occur, and the fact that the soils stay moist until well into the growing season, particularly at the base of the patch. Floristic surveys of some 35 snow patches across the Bogong High Plains over the 1995-96 period revealed that most were in a degraded condition, with high amounts of bare ground, and the snow patches on Mt Fainter, like the wetlands there, are particularly degraded. It is impossible to stop cattle from utilizing and further degrading these fragile communities under present grazing practices.
Conclusions Based on research conducted in the Victorian and New South Wales alps over 50 years, grazing has been shown to be at odds with the protection of soils and vegetation in alpine environments. Studies on the Bogong High Plains and in the Kosciuszko high country have emphasised two clear impacts of livestock on Australian alpine ecosystems:
Any claims made with respect to the benefits of grazing to alpine ecosystems are not supported by scientific evidence. There is no evidence that shrub cover is reduced by cattle (and that therefore cattle reduce the fire risk). There is no evidence that cattle promote wildflower diversity - all of the long-term evidence points to the opposite effect. Where grazing has been excluded for lengthy periods from the Kosciuszko high country and parts of the Bogong High Plains, there has been a marked improvement in vegetation cover and catchment protection, although in badly degraded communities the recovery has taken decades and sometimes required active restoration. Such improvement in condition will not occur if grazing continues. The Bogong High Plains are within the extensive Victorian Alpine National Park, and are part of the Australian Alps National Parks system incorporating alpine and subalpine national parks in Victoria, NSW and the ACT. Currently, only the Victorian Alpine National Park is subject to grazing by domestic livestock. A primary management aim within national parks is to conserve natural ecosystems and the natural processes which give rise to these features. The presence of domestic livestock is inconsistent with these basic objectives of national park management.
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