Simon has been researching the ability of animals to migrate between habitats and the state of connectivity of our protected areas, with a particular focus on the Blue Mountains, both in the present and under the influence of a changing climate.
Australian World Heritage Areas have recently been suffering from the effects of climate change that are only expected to increase in the future. Earlier this year, unprecedented bushfires struck the Tasmanian Wilderness and this has been followed up with an equally devastating bleaching event at the Great Barrier Reef. At a time when there is a clear need for a concerted effort to tackle climate change, the Federal environment department has been lobbying UNESCO to have all mention of Australia removed from its recent report on climate change.
Unfortunately, these World Heritage sites are not the only Australian protected areas at risk from a rapidly changing climate. The fragmented nature of our protected area network means that even large national parks and reserves, such as the World Heritage listed Blue Mountains west of Sydney, are likely to see their conservation values decline unless action is taken.
Why is habitat fragmentation such an issue for the Blue Mountains?
Climate change predictions suggest major decreases in winter and spring rainfall in south-eastern Australia are likely in addition to increased temperature and fire intensity. Around the world species already appear to be responding to climate change by shifting distributions. Shifting pole-wards or to higher elevations is expected to be one of the main responses to climate change which in the relatively flat continent of Australia could involve long overland shifts, as has occurred during periods of climate change in geological history.
Unfortunately, habitat fragmentation may inhibit such large-scale species movements. As such the isolated nature of our protected areas means they are unlikely to be able to support species needing to transition to new areas of habitat.
The formal reserve system of south-eastern Australia largely represents the areas of land not deemed important for agriculture, mining, forestry and settlement. The result of this is that reserves are essentially ecological islands surrounded mainly by agricultural land. Eastern Australia’s forests have some resilience to climate change thanks to their north-south alignment along the Great Dividing Range and altitudinal gradients but this has been reduced since European settlement.
Isolation of the Blue Mountains, and other areas of habitat along the Eastern Ranges, may be of particular importance as Australia’s generally flat topography means that there are limited opportunities for species to adapt to a changing climate by relocating to higher elevations.
A need for conservation at larger scales
The task of reconnecting habitat is made difficult by a lack of knowledge. The movement ecology of many species, the way they react to measures designed to increase connectivity and their responses to climate change are poorly understood. This lack of information is a key barrier to attempts to improve connectivity.
The success of our approaches to conservation and connectivity can be lessened by the need to make generalisations based on the knowledge of a few species. To address this there is a need to assess regional-scale criteria in order to reveal patterns of response to habitat and management on larger scales and provide some balance between generalisations and knowledge at a finer resolution. In this way a ‘one-size-fits-all’ approach common to large-scale conservation planning can be avoided leading to increased sophistication of conservation program design.
In the future, opportunities may arise that are able to address climate change mitigation and biodiversity conservation at the same time. A carbon price that reflects the true social cost of carbon emissions may incentivise environmental tree plantings for carbon storage which may also serve to increase habitat and connectivity under the right circumstances.
Although slower to proceed than replanting, natural regrowth may complement replanting well as it contributes to landscape heterogeneity and supports high species diversity. In some areas of south-eastern Australia a continuing process of land abandonment may double the amount of regrowth and make an important contribution to species conservation. In any future carbon economy, there are likely to be further opportunities to expand regrowth in agricultural landscapes which have the potential to be of benefit to connectivity management.
With its size and altitudinal gradients, the Blue Mountains have the potential to play an important role in the overall connectivity of the Eastern Ranges as the biodiversity of the south-eastern Australia feels increased climate pressure throughout this century. To enable this, its connectivity with habitats across the landscape needs prioritisation and further support for region-scale connectivity programs that incorporate the Blue Mountains and other critical yet isolated habitats is required.
Our approach to climate change adaptation and mitigation must include attempts to increase the connectivity of habitat to give our wildlife the best possible chance to adapt to new climate conditions and help limit the loss of species during the rest of this century.