Australasian Science: Australia's authority on science since 1938

A Clear Case for Regrowth

By Melissa Bruton and Clive McAlpine

Despite evidence that regrowth vegetation has equivalent habitat value to intact vegetation, Queensland has amended legislation protecting high-value bioregions from clearing.

Last year the Queensland Government introduced legislation that removed protection for several categories of regrowth vegetation. Previously, regrowth that had not been cleared since 1989, and occurred in ecosystems with less than 30% of their original extent remaining, was protected from most clearing activities.

This protection has now been removed. WWF has calculated that, as a result of these changes, 700,000 ha of previously protected high-value regrowth can now be cleared for “high-value agriculture” in Queensland. Many claim these changes represent a significant blow to biodiversity and ecosystem restoration in Queensland.

Why were these regrowth protections set up in the first place? At the end of the 20th century, vegetation in Queensland and New South Wales was cleared at rates similar to the rainforests of Brazil. Clearing was so effective that, by the turn of the 21st century, 45% of Queensland’s regional ecosystems were reduced to less than 30% of their original extent – a level that puts those ecosystems at risk of losing biodiversity and function.

In 2004, Queensland enacted new vegetation laws that significantly reduced the rates of clearing. The belief at the time was that the only way to increase the extent of these threatened ecosystems was to protect regrowth and allow it to mature.

The most heavily cleared areas of Queensland are the woodlands of the Brigalow Belt bioregion. Australian woodlands possess a rich diversity of reptiles. Reptiles are an important component of these nutrient-poor ecosystems because they ensure energy and nutrient flow between invertebrates and higher order predators.

Our research in the Brigalow Belt bioregion found that there is no difference in the diversity, dominance and composition of reptile communities in regrowth and intact woodlands. In fact, reptile communities in regrowth woodlands were indistinguishable from their corresponding communities in intact woodlands.

The most interesting part is that the regrowth woodlands in our study were relatively young – between 10 and 23 years old – with only half the canopy height of intact areas. In other words, for the reptiles we studied, regrowth doesn’t have to be “old” to possess equivalent habitat value to intact vegetation.

Queensland’s woodlands are dominated by acacias, which naturally sucker (send up shoots from roots left in the ground). This means a cleared site can quickly regrow, offering cost-

effective, large-scale opportunities to restore ecosystems and reduce the biodiversity declines that have been caused by the over-enthusiastic clearing of vegetation. By comparison, many of the restoration efforts in southern Australia, and other parts of the world, require planting and follow-up management, which generally limits them to small-scale efforts.

Developing cost-effective restoration programs for threatened ecosystems will become increasingly important if the world is to meet the United Nations target of restoring

150 million ha of disturbed and degraded land globally by 2020. When the goal is to increase biodiversity in a disturbed landscape, passive regrowth woodlands offer cost-effective and valuable complementary habitat to intact woodlands. Our finding that regrowth is a high-value habitat for reptile communities provides valuable information that will assist in the cost-efficient recovery of highly modified and reptile-rich subtropical woodland regions.

The former vegetation management laws in Queensland acknowledged the value of passive regrowth vegetation by protecting regrowth areas in threatened ecosystems from most clearing activities. Unfortunately, the recent reforms by the current Queensland Government removed these legal protections. The protection of high-value regrowth in Queensland has been traded for the expansion of “high-value agriculture”.

However, at no point in the Vegetation Act 1999 (Qld), or subsequent amendments, is “high-value agriculture” defined. So what are we really trading?

If we take a commercial approach and define “high-value agriculture” as the top five Australian agricultural exports (by value) for the last financial year (2011–12), then we are looking at wheat, beef, cotton, wool and wine. If so, then the changes have effectively removed protections for the vast majority of high-value regrowth in Queensland, particularly for the woodlands of the Brigalow Belt and Mulga Lands bioregions.

It would seem that scientific consultation regarding the impacts of the proposed amendments to regrowth legislation on agricultural production, the environment and society have not been considered evenly, or in any depth. Studies such as ours are suggesting there are strong arguments to protect high-value regrowth in the interests of biodiversity conservation.

Melissa Bruton and Clive McAlpine are members of the Environmental Decisions Group, and based at the University of Queensland.