Overall
At the time of its inscription in 1988, the Wet Tropics of Queensland World Heritage Area was identified as ‘an essentially intact ecosystem exhibiting a low level of human impact, despite past clearing and logging and pressures from infrastructure and invasive species’.
From European settlement until the area’s World Heritage listing, logging was widespread across the Wet Tropics. However, much of the area’s steep terrain made it inaccessible, so a large proportion of forest cover remained. In contrast, in only a small proportion of the area, several disturbances detracting from its natural integrity were scattered throughout the property, including transmission lines, access roads, mine sites and more extensive selectively logged areas.
Factors impacting the area’s integrity
- Habitats within the Wet Tropics of Queensland Area are well-protected, and habitat integrity and connectivity are improving, but there are multiple and sometimes conflicting land use pressures outside the area that impact its World Heritage values.
- Due to its shape, the area has a naturally high boundary-to-interior area ratio, intensifying the effects at its edges.
- The area is separated into several sections, fundamentally fragmenting it.
- The area protects many high-altitude rainforest locations with steep and rugged terrain. Still, it does include flatter, more accessible land towards its boundaries.
- Agricultural use prevails adjacent to the area in the more accessible locations, preventing species from easily moving through the larger landscape, reducing overall ecological connectivity and gene flow between populations of Wet Tropics species, and increasing their vulnerability.
- Climate change impacts (see below).
Climate change
Climate change is the leading threat to all the natural values captured by the four World Heritage listing criteria. The Wet Tropics Management Authority identifies it as such in its reporting, including in its 2023-24 State of the Wet Tropics Report. Without significant, sustained, and strong action on climate change at all government levels, the Outstanding Universal Value of the Area will likely be significantly impacted in the coming decades.
Climate change particularly threatens montane species restricted to the upland forests, including many threatened birds, mammals, frogs, and plants. Due to the area’s biogeographic history, these species are often naturally rare and vulnerable, highly locally endemic, and frequently ancient Gondwanan species of high conservation significance. Additionally, climate change impacts of hotter and drier dry seasons result in some regional ecosystems drying out, which puts them at higher risk of damaging wildfires.
Since the area’s listing, several species of frogs are presumed to have become extinct due to synergistic pressures, including an introduced pathogen. Despite recovery and action plans, trends indicate that some other threatened species are deteriorating. The spread of invasive weeds, pest animals, such as yellow crazy ants, and plant diseases, such as myrtle rust, pose management challenges that are complex and resource-intensive.
Disruption of the traditional burning regimes used by Rainforest Aboriginal Peoples (Traditional Custodians of the Wet Tropics of Queensland Area) has impacted the area’s non-rainforest ecosystems, such as wet sclerophyll forest. These ecosystems evolved under the influence of fire and rely on specific fire regimes to retain their integrity. Without the conditions they have adapted to, these ecological communities are being lost to encroaching rainforest vegetation, with a corresponding loss in their dependent species, including some threatened species.
