Contemporary livestock carrying capacities for pastoral properties in Northern Australia: a methodology for integrating objective data on pasture growth and condition

摘要

Stocking rate is often the most important and manageable factor influencing the profitability and environmental sustainability of pastoral properties. Methods for determining carrying capacity, and therefore stocking rate, include subjective approaches based on land manager experience, long- term 'benchmark' stocking rates and techniques using computer-aided predictions of pasture growth. This paper presents a new approach for objectively calculating short-term livestock carrying capacities of pastoral properties by integrating remotely sensed ground cover assessments as a proxy for land condition. The study region was three commercial pastoral properties in the north Australian pastoral region (above 26A degree S). Two properties were situated in the Victoria River District of the Northern Territory and a third in the Kimberley region of Western Australia. Annual pasture growth was estimated using GRASP, a deterministic, point-based, native pasture model developed for semiarid and tropical grasslands, which was calibrated for the different land types in the study region. Carrying capacity estimates were further refined by investigating trends in landscape cover change between years using data from satellite imagery assessment. These tools have been shown to be useful for inferring land condition and pasture growth within these regions of northern Australia but had not been integrated before this study. This study developed an approach for inferring rangeland pasture condition and applying it to refine short-term carrying capacities, thus aiding decision making. The approach developed in this study is considered to be more applicable for commercial land management than currently available methods for determining carrying capacities on pastoral properties in northern Australia.