CHALLENGES
BIODIVERSITY
Almost all of the Wet Tropics 185 Regional Ecosystems are under threat, with 18 listed as 'Endangered' and a further 134 listed as ‘Of Concern’. Impacts are being felt across the Wet Tropics, from Critically Endangered Mabi Forest on the Atherton Tablelands to Critically Endangered Littoral Rainforest and Coastal Vine Thickets on coastal lowlands.
Land clearance and the spread of invasive weeds are key threats to the abundance and diversity of Wet Tropics flora and fauna. Land clearance is continuing to fragment remnant vegetation, resulting in changes to the floristic composition, structure and microclimates that comprise the different Regional Ecosystems.
In particular, edge-related effects from land clearance is making remnant vegetation vulnerable to invasive weeds, stream bank erosion and predation by domestic and feral animals like cats and pigs, and internal fragmentation from road and other linear infrastructure is creating barriers to the movement of rainforest species and providing conduits for pest and weed intrusion.
The loss of habitat and connectivity between areas of remnant vegetation is resulting in significant loss of functionally important species, like the critically endangered Southern Cassowary — a ‘keystone’ species whose conservation is crucial to the maintenance of tropical rainforest and the survival of other species. Southern Cassowary are a main disperser of rainforest plant seeds, being the only disperser of large, fleshy-fruited seeds over long distances and, without which, there is relatively rapid and permanent change in the species composition of rainforests.
Coastal lowlands ecosystems are a particular focus of the Foundation, where only 20 per cent of the original native vegetation remains. Palustrine wetlands are particularly important. These inland, non-tidal wetlands are characteriSed by the presence of trees, shrubs, and emergent vegetation.
Palustrine wetlands provide important habitat and nursery for aquatic species, birds, mammals and migratory species, have a critical role in regulating water flow during and post flood events within the broader coastal lowland landscape, and are nature’s kidneys that filter and improve water quality entering the river systems and the GBR Lagoon.
OUR PRIORITIES & KEY ACTIVITIES
Our priorities are to maintain areas and species of high biodiversity value and ecosystems critical to the survival of ecological communities, populations and particular threatened species. Our key activities include identification and management of strategic areas, rehabilitation and reinstatement of key habitat (including particular threatened flora species and fauna habitat), creation of connectivity corridors and management of threatening processes (including invasive weed control).
WATER QUALITY
Water quality in Wet Tropics watersheds (catchments) underpins terrestrial and aquatic biodiversity, including for both the Wet Tropics terrestrial and GBR marine environments. Riparian vegetation, where terrestrial and aquatic ecosystems overlap, has a particularly important role. There has, however, been substantial removal of riparian vegetation, which has:
• impacted aquatic habitat, by causing bank erosion, in-stream sedimentation, reduced water depth, increased water temperature and reduced levels of Dissolved Oxygen;
• disrupted food supply chains, by decreasing the organic matter (woody debris and leaf litter) and source of nutrients needed to support stream ecosystems;
• changed watercourses, by increasing sedimentation, formation of in-stream islands, creation of erosion hotspots and creek avulsions;
• reduced groundwater recharge, by speeding up floodwater and rainwater runoff;
• reduced habitat connectivity, by disrupting the vegetation continuum between coastal lowland and mountainous areas; and
• increased impact of manmade pollutants on marine life, by reducing the vegetation buffer between developed areas and waterways.
Further, biodiversity of coral reefs across the GBR are being impacted by poor water quality emanating from Wet Tropics rivers. This includes loss of coral cover, changes in reef composition and decline in species diversity.
Manmade fertilisers are responsible for the threat of increased predation by Crown of Thorns Starfish (COTS), which account for a 40 per cent loss of coral cover since 1987. Wet Tropics rivers contribute approximately 86 per cent freshwater input to the COTS Outbreak Initiation Zone between Lizard Island and Cairns. In particular, flood plumes during the wet season cause acute, short-term changes in water quality, in which high nutrient, high sediment and low salinity coincide with the COTS spawning season.
A further 93 per cent of the GBR’s individual reefs have been impacted by the 2016 global coral bleaching event. While increased sea temperatures are the primary cause of coral bleaching, coral is more susceptible to and less able to recover from bleaching events when exposed to the chronic pressure of poor water quality from pollutants contained in land-based run-off.
OUR PRIORITIES & KEY ACTIVITIES
Our priorities are to maintain and rehabilitate aquatic ecosystems, reduce manmade fertilisers and pollutants entering Wet Tropics waterways and improve riparian connectivity between the coastal lowlands and mountain foothills. Our key activities include improving bank stability, reinstating riparian vegetation, reinstating water flow and creating vegetation buffers.
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CLIMATE CHANGE
Ecological succession is a natural process, as the species structure changes within an ecosystem over time to suit the climate and other factors. However, modelling suggests that the current vegetation composition of the Wet Tropics is at high risk of disappearing within the coming decades and, as a result, may no longer exist in their current form anywhere in Australia by 2050.
The areas in the Wet Tropics most at risk include Port Douglas and areas west and south of Atherton, extending toward the coast around and south of Mission Beach. While some native plants will adapt and colonise new areas, they could replace and threaten populations of other native species.
Exotic invasive weeds be a primary threat to biodiversity, as they are generally able to adapt more quickly to localised changes in climatic conditions than native species. In particular, a new set of weed species are likely to emerge in response to increased temperatures, changes in rainfall patterns, increased salinity in waterways, increases in CO2 levels, more extreme weather/events, more frequent frosts, changes in phenology (timing of plant growth and reproduction) and changes in land use as humans adapt.
In addition, an abundance of sleeper weeds (weeds that currently appear benign, but have the capacity to spread rapidly) will become new threats to biodiversity during global warming and an increasing management challenge for natural resource management (NRM) regions.
OUR PRIORITIES & KEY ACTIVITIES
Our priorities are to maintain areas and species of high biodiversity value and ecosystems critical to the survival of ecological communities, populations and particular threatened species. Our key activities include identification and management of strategic areas, rehabilitation and reinstatement of key habitat (including particular threatened flora species and fauna habitat), creation of connectivity corridors and management of threatening processes (including invasive weed control).