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
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.
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.