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Abstract
Scotch Broom is an invasive weed in many subalpine ecosystems. It often has
substantial negative effects on ecosystem structure and functions. Decisions on
optimal management strategies require predictions of the rates and patterns of Scotch
Broom spread. This paper explores the environmental and management factors that
influence the density and rate of spread of Scotch Broom in Barrington Tops National
Park.
The National Parks and Wildlife Services in a cooperative exercise with the State
Forest prepared aerial maps showing Scotch Broom infestation in the Park for 1989
and 1999. These maps were used to generate data for the analysis. Map reference
points 1km apart along the boundary of the 1989 area of infestation were examined
and 1999 areas and densities were measured. Environmental factors measured include
natural vegetation type, natural vegetation density, soil type, slope, altitude and the
presence of private property or crown land. Areas of natural disaster, feral animal
activity and National Parks and Wildlife Service management activities were also
included in the analysis. We acknowledge the help of the NSW National Parks and
Wildlife Service for providing us with the information and data for the analysis. Lack
of data on rainfall at the specific map reference points is a possible limitation of the
study.
OLS, Probit and Multinomial Logit models were used to analyse different forms of
the dependent variables measuring the density and the spread of Scotch Broom. The
analysis shows that the treatments undertaken by the National Parks and Wildlife
Services significantly reduce the spread of broom. In fact when this management is
undertaken the probability of spread is reduced by 18.9% and on average treatment
reduces the spread in kilometrs by 45%.