The Rowsley Valley is a picturesque volcanic lava flow located 50kms North-West of Melbourne and was among the earliest regions in Victoria to be settled by Europeans. It has a history just as fascinating as it is devastating, with many invasive species finding ideal conditions in the Valley, through either human intervention or natural selection. Rowsley has been subject to a large sustained investment through various government agencies and bodies over a 20 year period, and makes for an interesting case study.
Early history suggests Rowsley was originally part of the territory of the Kurung tribe, part of the Wadawurrung Aboriginal Clan, and was later part of the white settlement squatting run known as “Glenmore” which then took in the majority of the Rowsley Valley. Soon after 1840 the land was surveyed and divided up for sale, with conditions on the purchase requiring owners to clear the land of trees and vegetation.
Given the fragility of the soils and hillsides in Rowsley, it did not take long the valley to be denuded and prone to erosion. To make matter worse, in 1865 rabbits began to spread across Victoria, with Rowsley Valley became infested heavily with them. The rabbits dominated the landscape and prevented regeneration of indigenous and pasture species.
Serrated tussock was first found around the Melbourne region in the 1950s and in the Rowsley Valley in the following decades, albeit in low numbers and density. However, the combination of a low rainfall, high rabbit numbers, poor vegetation cover, marginal farming opportunities, steep escarpments and a series of droughts, resulted in the serrated tussock getting a strong hold in the area. The turning point for the invasion of serrated tussock is said to be around the 1982-83 drought, with many landowners going into the drought overstocked. This resulted in the entire valley being completely denuded of grass and vegetation, providing serrated tussock with the chance to fill the blank canvas.
Moorabool Network Landcare Facilitator, Roger McRaild, said “Farmers and land managers were slow to respond to the drought, leaving stocking rates much higher than the land could support, especially when rabbit pressure is considered. Paddocks were bared out, top soil blew away and serrated tussock, which had been present at low levels for some time, took full advantage of the disturbance”.
The dire situation and massive infestations of serrated tussock in the Rowsley Valley inspired the beginning of the large investments from government agencies, catchment management authorities, Landcare groups and landowners over a 20-year period. Projects implemented in the valley have included revegetation with indigenous species, changes in agricultural management practices, large scale treatment of serrated tussock and prevention of further spread.
Emma Muir, from the Port Philip and Westernport Catchment Management Authority, added that “The Authority is proud to have been an active contributor to the health and productivity of the Rowsley Valley over the last 15 years through the Grow West Program. Since 2003, Grow West has planted in excess of 200,000 trees, held four community planting days in the Rowsley Valley and has funded many serrated tussock removal programs”.
Landowners have conducted coordinated and integrated approaches to treat serrated tussock, with government bodies assisting with numerous rounds of funding over the past two decades. The result has been a huge reduction in serrated tussock and large scale native vegetation belts, aimed at preventing further spread of serrated tussock, and stabilising the fragile erosion prone soils.
President of the Rowsley Landcare Group, Jacob Pearce, acknowledges the hard work and large investment in improving the health of the valley. However, he also notes the large risk that serrated tussock poses to already treated areas “Even in areas that have been well treated, ongoing pasture management is a major issue, any overgrazing of pasture places a paddock at great risk of re-infestation due to the local seed bank and spread of seed from surrounding areas each year. I think the challenges for the area is around learning to live with the risk of serrated tussock”.