- Biodiversity
Protecting and Restoring Natural Biodiversity
In its simplest form, natural biodiversity (biological diversity) is the variety of all native life forms (eg plants, animals and micro-organisms). It would be impossible to identify all the different species in the catchment and what threatens each of them, but by protecting as much of each vegetation community (eg woodlands, grasslands etc…) as possible, the life that depends upon this vegetation can be protected.
Unfortunately the remaining native vegetation (remnant vegetation which has not been planted) is threatened by lack of regeneration, damage caused by stock, weeds and other pests, changes to natural water flows, and chemical spray drift.
Animals using this vegetation are also under threat due to the lack of links (corridors) or stepping-stones allowing them to find food & shelter as they move from one patch of vegetation to another. The on-ground works suggested below may help alleviate these threats and increase biodiversity protected in the catchment.
Possible On Ground Activities
- Fencing to exclude stock from remnant (non-planted) vegetation.
- Revegetation with local native species (local provenance should be used wherever possible) and a good mix of species used in most cases. All revegetated areas must exclude grazing or have a managed grazing plan.
- Buffers and corridors ideally should be greater than 30m in width and connect with remnant vegetation.
- Control of problem weeds in remnant areas should use minimum disturbance methods so as not to damage existing vegetation.
- Maintaining Land Productivity
Managing Land and Soils Sustainably to Enhance Land Productivity
Soils sustain the productive capacity of the catchment. Prevention of soil erosion by wind, water and stock is a priority land management issue in the Upper Torrens catchment. Erosion can negatively effect farm productivity by reducing the areas of productive land. Transported soil will also have a negative effect on the areas in which it is deposited such as remnant vegetation, rivers and our marine environment. There are also large social costs that accrue from soil erosion including health issues from atmospheric dust and costs in repairing roads, infrastructure and fence lines.
One of the main contributing factors to risk of erosion, besides the inherent nature of the soil, is the percentage of vegetative surface cover. Surface cover can be maintained with appropriate stock management and by reducing tillage. Some areas, such as sheep camps on hilltops and eroding gullies, seem to suffer from erosion regardless of the management adopted. It is recommended that stock are removed from such sites.
Other sites may require infrastructure to manage grazing more appropriately or a change from cropping to a permanent pasture system which will ensure surface cover is maintained throughout the year.
The direct drill method of pasture establishment will ensure a low risk of erosion. Other cultivation methods can damage soil structure and the exposed areas are more prone to erosion until the pasture is established.
Windbreaks are encouraged to protect stock and pasture.
Possible On Ground Activities
- Establishment of windbreaks of a suitable design.
- Fencing to exclude stock from eroded watercourses placed a minimum of 5m from the edge of the bank. On severely eroded banks the fence may need to be placed further away.
- Rotational grazing management and fencing to land classes.
- Protecting Riparian Zones
Protecting our Rivers, Riparian Vegetation and Aquatic Life
The Upper Torrens Catchment has endured extensive changes to its character and ecological functioning since European settlement. Issues such as sedimentation, nutrients and chemicals entering watercourses and altered flow regimes have impacted upon the fish, macro-invertebrates, frogs and water dependent vegetation in our streams.
Riparian vegetation, including aquatic plants in the stream channel, has also been altered by threats such as stock, weeds and modifications to flow regimes. The permanent pools and remnant riparian vegetation that remains in the catchment provide vital habitat for our aquatic life. Features such as woody debris, sedges and rushes in our watercourses provide valuable refuge during times of high flow allowing them to safely migrate along a watercourse. Removal of stock will allow vegetation to regenerate and can reduce nutrient input and creekline erosion.
Improving land management practices may also be required to prevent sedimentation and creekline erosion (see "Managing Our Land And Soils Sustainably"). Restoring riparian vegetation and controlling environmental weeds are also important steps in reviving our rivers.
Possible On Ground Activities
- Fence off watercourse from stock. Fence off dam from stock. Fencing placed a minimum of 5m from the edge of a stream bank (if fences are placed too close to the edge of a stream bank, especially if eroded, then it is likely the ground may erode underneath the fence causing it to collapse).
- Revegetation of watercourses, as with revegetation of buffers and corridors, must be greater than 30m in width and use local native species.
- Environmental weed control in remnant riparian areas should use minimum disturbance methods so existing vegetation is not damaged. In riparian areas, herbicides should not be used where there is permanent water unless cut & swab or drill & fill methods are used. When using these methods Roundup Biactive® is the preferred chemical. Most herbicides and the surfactants used with them can have significant impacts upon frogs and some fish populations.
- Relocation of watering points associated with watercourse/dam fencing.
- Salinity and ProductivityAdd and rearrange any components you want.
