Assessment of the economic and ecological impacts of remnant vegetation on pasture productivity

Abstract

The decline of remnant native vegetation in Australia is a national concern, with mounting community pressure on private landholders to actively manage and conserve the remaining vegetation on their properties. One of the major concerns of landholders in retaining and managing remnant vegetation in the agricultural landscape is the lack of information and understanding about the costs and benefits potentially associated with remnant vegetation, and how these values are linked to ecological functions. This paper focuses on the impacts of remnant vegetation on pasture productivity. Knowledge of the economic impacts of remnant vegetation on pasture productivity and associated agricultural output is currently limited, while the ecological relationships are better known but may vary with species and environment. Based on a study area near Gunnedah in northern New South Wales where farm survey data and GIS information were available, a model that incorporates agricultural and biophysical attributes to explain pasture productivity was developed. The results indicate that the value of pasture output per farm may be increased by having a certain proportion of pasture area under dry sclerophyll or woodland vegetation. Gross value of pasture output was at its highest level when the proportion of tree area across the farm was at 34%, with no further increases in output being achieved beyond this point. These results suggest that the competitive influences of trees present in the pasture system may begin to outweigh the stimulatory effects when this proportion of tree area is exceeded.