27 November 2010

Watershed Landcare hosted a field day on Monday that saw a busload of graziers head up to Hargraves. The bus visited two properties to learn how grazing can influence biodiversity in a grassy woodland. In particular we discussed how to prevent or reduce the encroachment of a single shrub species such as Sifton Bush.

Colin Seis, grazier from Gulgong and developer of the Pasture Cropping technique (www.pasturecropping.com) and Andrew Knop, Biodiversity and Vegetation Catchment Officer with the Central West Catchment Management Authority were guest speakers for the day and provided valuable insights into the psychology of woody shrubs, mobs of sheep and cattle, and of the grazier!

Andrew explained that the vast majority of woody shrub species are actually really poor competitors; they’re slow off the mark. In diverse, perennial, grassy woodlands, millions of shrubs and tree seeds are germinating and dying all the time due to competition by the grasses. Continuous grazing of a paddock decreases the diversity of plants as the tastier species decrease in numbers. Overgrazed plants lack enough solar panels (leaves) to generate the energy they need to grow and weaken as they draw on root reserves to push out new leaves. Over time, bare patches start to appear and that’s recipe for shrub and tree encroachment.

Col encouraged graziers to start managing grazing to give the more palatable species a chance to grow. “Most of us focus on the things we want to get rid of in grasslands, not on encouraging the plants we want more of” he said. This generally ends up in a vicious cycle, because without a change in grazing management, the treatments we impose ends up perpetuating the environment those shrubs germinate and do well in.
The more palatable grasses need a chance to recover fully before they’re grazed again.

Mob behaviour played an important part in managing grasslands for biodiversity. Larger mobs behave differently to smaller mobs that can graze at their leisure.
Larger mobs are like a group of kids that have been let into a room with a table full of lollies, ice cream, cakes, broccoli and cabbage. The ‘mob’ will be thinking “I’d better not miss out on some of this good stuff” and they’ll take a bite of some broccoli or cabbage whilst trying to get a bite of the ice cream and lollies.

It’s the same with a mob of livestock, and that’s how more palatable species are encouraged and maintained in grassy woodlands. Moving large mobs requires careful monitoring and management however, the difference between enough grazing and overgrazing can be 2 and 4 days in a paddock.

This field day was made possible by the New South Wales Government through it’s Environmental Trust as part of Watersheds’ “Building Environmental Capacity in the Cudgegong” project.

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