The extent and status of remnant vegetation in Queensland and its implications for statewide vegetation management and legislation

Abstract

Vegetation classification, survey and mapping provide key information underpinning the implementation of statewide vegetation management legislation and associated policies in Queensland. This paper summarises: (i) the Queensland Herbarium survey and mapping methods and land classification system and its role in vegetation management legislation; and, (ii) the current extent and rate of vegetation clearing by bioregion, sub-region and Broad Vegetation Group; (iii) and the amount of vegetation protected under legislated statewide bioregional and regional ecosystem thresholds. Information also is provided on the pre-clearing and current extent by 18 Broad Vegetation Groups and the area of non-remnant woody vegetation by bioregion. The implications for vegetation management are discussed, along with a comparison of clearing statistics derived from other studies that use different classification and mapping methodologies. The majority of Queensland has relatively continuous native vegetation cover (82% remnant native vegetation remaining in 1999). The productive soils of the southern part of the Brigalow Belt, lowlands in South-east Queensland, New England Tableland and Central Queensland Coast have been, however, extensively cleared with 7–30% of remnant vegetation remaining. Between 1997 and 1999, the annual rate of remnant clearing in Queensland was 4460 km2 of which over 60% occurred in the Brigalow Belt bioregion. A greater proportion of this recent clearing occurred in Broad Vegetation Groups that are associated with less fertile and/or more arid parts of the State compared with pre 1997 clearing. For bioregions and regional ecosystems where past clearing has been extensive, a substantial proportion (50–91%) of the remaining vegetation is protected by bioregional and regional ecosystem thresholds prescribed under statewide legislation and associated policies. For other bioregions and regional ecosystems, other factors such as rainfall, soil and areas of high conservation value are likely to play a larger role in determining the amount of vegetation protected. However, the effectiveness of the Queensland legislation cannot be assessed until regional planning processes have been completed and all criteria addressed.

Preliminary assessment of gidgee (Acacia cambagei) woodland thickening in the Longreach district, Queensland

“…Data were assessed with and without clearing (1995 remnant vegetation coverage, Queensland Herbarium). The Vegetation Management Act 1999 (Queensland) defines remnant vegetation as having at least 70% of the height and 50% of the cover of the dominant stratum, relative to the undisturbed height and cover of that stratum and dominated by species characteristic of the vegetation's undisturbed canopy (Wilson et al 2002). Thus some areas that were cleared between 1951 and 1994 have sufficiently recovered their pre-clearing structure to be classified as remnant.…”

“…The study area is defined as the area of alluvia and fine grained sedimentary substrates within the Mitchell grass downs bioregion on the Longreach 1 : 250 000 map sheet (23-24 • S; 144-145 • 30 E) as determined from the mapping data of the Queensland Herbarium (Wilson et al 2002). The sampling strategy employed the 1 km national mapping grid as the sampling unit.…”

“…For each km 2 cell, woody cover (%) was assessed from 1951 black and white (1 : 50 000) and 1994 colour (1 : 80 000) aerial photography by an experienced interpreter (R. Fairfax) with reference to pre-established black and white patterns of known cover. The cover assessments were established as a GIS coverage and used in conjunction with existing Queensland Herbarium regional ecosystem (Wilson et al 2002) and remnant mapping coverages to perform a range of analyses quantifying change. The regional ecosystem coverage was collapsed to the km 2 cell unit of this study, thus, where cells contained more than one regional ecosystem, each cell was assigned the most prevalent regional ecosystem.…”

“…Gidgee and brigalow dominated similar areas of woodlands and forests throughout Queensland (about 90 000 km 2 ) but the brigalow has been far more extensively cleared for pastoral development. Only about 11% of brigalow forests and woodlands remained in the brigalow belt biogeographic region in 1999, while at the same time gidgee forests and woodlands were about 72% intact in the Mitchell grass downs biogeographic region (Wilson et al 2002).…”

Potential aboveground biomass in drought‐prone forest used for rangeland pastoralism

“…The Mulga Lands biogeographic region in Queensland extends over an area of 18.6 Mha and has been mapped at 1:100 000 scale into Regional Ecosystem mapping units (Wilson et al 2002). This coverage represents these units prior to mechanical clearing when the Regional Ecosystems containing mulga represented 61% of the region (Fig.…”