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Range-ASSESS
(© 2002) Download Technical Report
(PDF format) Introduction to the context surrounding Rangelands Assessment in Australia Grazing land management was included as one of the options under Article 3.4 for Annex 1 parties to account for anthropogenic greenhouse gas emissions by sources and removals by sinks under recent agreements on the Kyoto Protocol (UNFCCC, 2001). In Australia, grazing of rangelands is the most extensive land use. Changes in management of these areas may have a significant impact on our country’s carbon balance. Whereas gains per hectare in carbon storage in rangelands from both biomass (vegetation) and soil are low, except where woodland and woody weed dynamics are affected by fire and clearing, the enormous areas covered by these grazed ecosystems provide a large potential carbon sink. The major sink potential if productivity is maintained (i.e., excluding the option to allow vegetation thickening or woody weed encroachment) lies in the reduction and reversal of degradation and the implementation of management regimes which return rangeland communities to something approaching their condition prior to the introduction of domestic grazing animals. Implementation of practices with positive carbon storage outcomes may have a major bearing on the economics of livestock production, and may be limited by social and cultural factors and potential changes to direct livestock emissions. There is considerable uncertainty surrounding the magnitude and reliability of rangeland sinks. Arid, fragile rangeland environments are highly sensitive to climatic cycles which may interact with grazing pressure to create periods of nil gain, or catastrophic degradation events which result in major carbon losses. One estimate suggests that the potential carbon store for the entire Australian rangeland is 48 Gt (gigatonnes). The many facets and temporal uncertainties surrounding the potential of rangelands sinks makes estimation of their potential benefits difficult for policymakers. A broad analytical framework at regional scale is needed to enable evaluation of the potential carbon storage benefits, risks of carbon loss and risks of increased emissions resulting from the inclusion the of grazing land management in the recent international agreement. In this paper, we describe a spatial framework for scenario analysis, document its underlying methodology and discuss potential applications and future improvements. Technical Report Description Range-ASSESS (2002) is a spatial framework for the analysis of management scenarios for carbon sequestration in the Australian rangelands. The framework uses a broad, scientifically accepted zonation of our rangelands and incorporated a knowledge-mining workshop to establish relative indices of carbon status within a simplified state and transition structure. Australia's rangelands were split into eight vegetation zones. Workshop participants were asked to populate a state and transition model with proportions of each zone in each state, and assign an index between 0 and 1 to soil and biomass carbon relative to an index on 1.0 for state 1 based on stable perennial vegetation. Participants were also asked to define the main drivers controlling transitions between carbon states. A spatial interface was constructed in the ArcInfo© GIS based on ASSESS (A System for Selecting Suitable Sites) and written in the AML© language. Spatial data layers describing stocking rate, carrying capacity, feral, native animal and woody weed distributions, clearing and other factors were constructed or acquired and used in conjunction with simple climate and socio-economic indices to implement the state and transition model structures for each vegetation zone in a simple modelling framework. This publication describes the basis for the state and transition structure and the construction of data layers describing factors controlling sequestration. Two example scenario analysis case studies are also presented to illustrate the potential of the approach, highlight the importance of the underlying assumptions and emphasise the need for Monte Carlo-style simulations to analysis sensitivity and error structure. Some future developments are also discussed. Range - ASSESS
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CRC for GA 2001-2003 |
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