Indicator: BD-13 Examples of the impact of grazing on biodiversity
Data
Case studies conducted by the Biograze team in different pastoral areas suggest that most native species appear to be surviving well in grazed rangeland areas, and are not at risk from further pastoral developments. There are however others that are so sensitive that they occur only where there is negligible grazing pressure.
Sites where there is negligible grazing pressure are typically a long way from water points. Domestic stock need to drink regularly, especially in hot weather. They are limited in how far they travel from water to graze before having to return to drink.
The number of waterpoints is increasing because it spreads the impact of grazing pressure among several evenly-spaced waterpoints rather than just one or two. The result is a reduction in the land which is lightly grazed, and this creates a problem for the native species that are sensitive to even modest grazing impact. As a consequence, some native species appear to be in decline and others may follow.
Source: CSIRO 2005, Biograze, viewed 6 Oct 2005, http://www.cazr.csiro.au/modelling.htm#biograze
| Bioregion | Pre-1750 (ha) | Extant (ha) | % remaining |
|---|---|---|---|
| Brigalow Belt South | 270 000 | 25 000 | 9.26 |
| Flinders Lofty Block | 1 500 000 | 5 000 | 0.33 |
| Murray-Darling Depression | 440 460 | 1 244 | 0.28 |
| Riverina | 2 750 000 | 26 871 | 0.98 |
| South East Coastal Plain | 60 000 | 25 | 0.04 |
| South Eastern Highlands | 450 000 | <22 500 | <5.00 |
| Tasmania | 80 098 | 13 617 | 17 |
| Victorian Volcanic Plain | 220 073 | 2 291 | 1.04 |
| TOTAL | 5 770 631 | 96 548 | 1.67 |
Source: Carter, O, Murphy, A M and Cheal, D 2003, Natural Temperate Grassland, viewed N/A, http://www.deh.gov.au/biodiversity/publications/grasslands/index.html.
Over five decades of research has shown that grazing and nature conservation in alpine areas are essentially incompatible land uses, in resepct to:
- the suitability of the Victorian alpine and sub-alpine ecosystems for livestock production in competition with other land uses;
- the effects of grazing on the hydrology of these ecosystems, and the downstream effects; and
- the effects of grazing on nature conservation values.
Source: Professor David Gillieson 2004, Submission to the Alpine Grazing Taskforce, Australian Academy of Science, Cabnerra.
What the data mean
Grazing in areas such as the rangelands, temperate grasslands and alpine areas has had a significant impact on resident biodiversity.
Data Limitations
Data covers some specific high risk areas, but is far from comprehensive. Very little recent trend data are available on the impacts of grazing on biodiversity.
Issues for which this is an indicator and why
Biodiversity — Pressures on biodiversity - Grazing pressure
Grazing by introduced herbivores can cause widespread damage through trampling and fouling of waterholes, selective, indiscriminate or close grazing of vegetation which in turn removes habitat of resident animal species, spreading weeds and trampling the home sites of ground-dwelling animals. Reduction in groundcover in turn exposes bare soil to erosion.
The quality of the mid-storey and understorey of forest and woodland ecosystems can be significantly modified as a result of grazing by livestock, or clearing for grazing, and simplification of these ecosystems can lead to a decline in species and genetic variability. In general, as grazing pressure increases, the total number of resident species and the populations of some of these species are reduced, reducing the overall diversity and resilience of the ecosystem.
Suitable indicators for measuring grazing pressure on biodiversity have not been developed. Research and examples may shed some light on the extent of these pressures.
Other indicators for this issue:
- LD-19 Land use and land use change
- LD-20 Total grazing pressure relative to net primary productivity
- LD-40 Current research into pressures and contributions of naturalised introduced species
Land — Direct pressure of human activities on the land - Species introduction and species change
Grazing pressure is a complex issue involving the introduction of non-native grazers and non-native pasture, as well as anthropogenic expansion of native pasture and native grazers. It is one of the principal ways in which introduced species can impact on the land.
Grazing pressure by both introduced grazers removes groundcover and nutrients from the land, often land that has already suffered substantial loss of cover and nutrients through land clearing and loss of associated biodiversity. It exposes the land to further nutrient loss through soil erosion. The loss of soil, soil ecosystems, soil nutrients and pasture biodiversity can preclude vegetation (either natural or agricultural) and other biodiversity from re-establishing.
Suitable indicators for measuring grazing pressure on biodiversity have not been developed. Research and examples may shed some light on the extent of these pressures.
Other indicators for this issue:
- LD-01 The proportion and area of native vegetation and changes over time
- LD-19 Land use and land use change
- LD-40 Current research into pressures and contributions of naturalised introduced species
- LD-20 Total grazing pressure relative to net primary productivity
- LD-35 Temporal and spatial correlation between changing fire regimes and species change
- BD-12 Examples of the impacts of fires on biodiversity
- IW-37 Examples of carp pressures and measures for removal and/or commercial catch
- IW-38 Cane toad distribution
- IW-39 Examples of significant wetland weeds
- BD-09 The change in extent of selected nationally significant invasive species
- BD-10 Examples of native species whose populations have declined where various invasive species have established resident populations
Land — Direct pressure of human activities on the land - Land clearing
Although grazing is primarily an issue arising from the pressure of introduction of new species to the land (pasture, in some cases, exotic pasture, replacing native vegetation and introduced animals replacing native animals), overgrazing also has the potential to completely remove ground cover, leaving bare soil. The indicator gives a spatial indication of where this is most likely to happen.
Other indicators for this issue:
- LD-01 The proportion and area of native vegetation and changes over time
- LD-03 Change in extent and proportion of woody vegetation, clearing and regrowth
- LD-17 Fragmentation of remnant vegetation
- LD-20 Total grazing pressure relative to net primary productivity
Biodiversity — Pressures on biodiversity - Invasive species
While the term “invasive” is usually used to refer to introduced species of plant and animal that have become naturalised in a wild state, in terms of scale of impact, the invasive impact of introduced plants and animals utilised in agriculture, and especially introduced grazing animals and introduced pasture for them to graze on, is much more significant.
Other indicators for this issue:
- IW-37 Examples of carp pressures and measures for removal and/or commercial catch
- IW-38 Cane toad distribution
- IW-39 Examples of significant wetland weeds
- BD-09 The change in extent of selected nationally significant invasive species
- BD-10 Examples of native species whose populations have declined where various invasive species have established resident populations
- LD-19 Land use and land use change
- LD-20 Total grazing pressure relative to net primary productivity
- LD-35 Temporal and spatial correlation between changing fire regimes and species change
- LD-40 Current research into pressures and contributions of naturalised introduced species
Further Information
- Biograze - Waterpoints and Wildlife
- Natural Ecosystems - Grasslands
- Sustainable grazing
- Native grasslands of the basalt plain
- Natural Temperate Grassland (Carter et al. 2003)
- Managing rangelands
- Alpine National Park... ...or cow paddock?
- Managing cattle grazing in the Victorian alps following the fires
- Fire and Australian alpine environments
Source: Fisher, A, Hunt, L, James, C, Landsberg, J, Phelps, D, Smyth, A and Watson, I 2005, Management of total grazing pressure, Canberra.
Key
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