Geoscience Reference
In-Depth Information
8
CHAPTER
An Independent Reliability Assessment
for the Australian Agricultural Land-Cover Change
Project 1990/91-1995
Michele Barson, Vivienne Bordas, Kim Lowell, and Kim Malafant
CONTENTS
8.1 Introduction...........................................................................................................................105
8.2 Methods ................................................................................................................................108
8.3 Results...................................................................................................................................109
8.4 Discussion and Conclusions.................................................................................................111
8.5 Summary...............................................................................................................................112
Acknowledgments ..........................................................................................................................113
References ......................................................................................................................................113
8.1 INTRODUCTION
Australia's first National Greenhouse Gas Inventory (NGGI) suggested that agricultural clearing
could represent as much as a quarter of Australia's total greenhouse gas emissions (DOEST, 1994).
The Agricultural Land Cover Change (ALCC) project was undertaken by the Bureau of Rural
Sciences (BRS) and eight Australian state government agencies to document rates of deforestation
and reforestation (1990/1991-1995) for the purpose of improving estimates of greenhouse gas
emissions (Barson et al., 2000). For this study, woody vegetation was defined as all vegetation,
native or exotic, with a height
20% (McDonald et al., 1990).
This was the definition of “forest” agreed to by state and commonwealth agencies for Australia's
National Forest Inventory (NFI) and the definition used for Australia's NGGI (NGGI, 1999). The
definition includes vegetation usually referred to as forest (50-100% crown cover), as well as
woodlands (20-50% crown cover) and plantations (silvaculture operations), but not open woodlands
where crown cover is < 20%. Woodlands occupy 112.0
2 m and a crown cover density of
¥
10
ha, followed by forests (43.6
¥
10
6
6
ha) and plantations (1.0
ha) (NFI, 1998).
The project documented both increases and decreases in woody vegetation over the period
1990/1991-1995 for the intensive land-use (LU) zone (Figure 8.1). Decreases or clearing were
defined as the removal of woody vegetation resulting in a crown cover of < 20%. Increases in
woody vegetation (usually due to tree planting) result in a crown cover that exceeds 20%). The
¥
10
6
105
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