As part of a national assessment of the vulnerability of biodiversity to climate change, terrestrial biodiversity has been identified as one of the most vulnerable assets in the country. Building ecological resilience to give ecosystems the best possible chance to adapt is a key management response[i].

Terrestrial species have already shown responses to observed climate change globally, in Australia and within the Glenelg Hopkins region. Geographic ranges have altered and some species are showing changes to the timing of life cycle processes, such as migration, flowering and breeding. This has resulted in modified genetic and physiological traits and potential mismatches in the timing of plant/pollinator relationships[ii].

Identified climate change impacts will also be exacerbated by other existing threats to biodiversity, such as habitat loss and land use change, introduced species and diseases, and altered water resources[iii]. Extreme events such as heatwave, drought, flood and bushfire, will also continue to have potentially catastrophic impacts on terrestrial habitats.

As the climate of the Glenelg Hopkins region becomes less suitable for existing vegetation communities, it is likely that there will be a gradual change in species composition and dominance as some species are replaced by others. This will lead to a shift in the distribution and structure of the community. While a lag could be expected between the climate shifting and the community response, some changes may develop earlier in response to the increased occurrence of extreme events such as floods, droughts and bushfire. Tropical invasive species are expected to expand their ranges with potential negative impacts for the Glenelg Hopkins region, while cool-climate invasive species are more likely to contract[iv].

One of the few habitat types for which there is information on the impact of climate change is eucalypt woodlands and grassy woodlands. The climatic variable with the strongest influence on these systems is moisture. It is likely that a drying climate will result in a decline in tree cover as well as an increase in annual grasses and a decrease in perennials.

Research completed through the National Climate Change Adaptation Research Facility[v] indicates that to reliably improve future landscapes for biodiversity relative to current ones, native vegetation cover needs to be restored to approximately 30%. At least this amount of native vegetation is required to maintain biodiversity. Although the total amount of vegetation restoration is more important than the detailed spatial configuration, it is recommended that effort is concentrated in small priority areas to achieve approximately 30% cover[vi].

Revegetation will play a key role in improving the extent, quality and connectivity of terrestrial vegetation in the Glenelg Hopkins region. Although it has been recognised that the methods currently available to managers and volunteer groups are inadequate to reliably assess if particular species and provenances will persist over the next hundred years[vii]. For example, for many eucalypt species, future climatic domains are projected to fall entirely outside their current climatic ranges within a few decades. Even widely distributed species may be vulnerable in particular areas near the hotter or drier extremes of their current distributions[viii].

Although some species may be lost to the region, there are other species for which the Glenelg Hopkins region may become suitable. For example, the river red gums of the Glenelg Hopkins region are in the cooler and wetter area of their range and it is possible that the region may become a refuge for river red gum and associated species. It is necessary that what remains is protected and enhanced and where possible connections between remnant patches are formed.

Connectivity is necessary to allow greater movement of species through the landscape in response to change. For forests, in particular, it is also important that mature trees are protected and that replacement trees are available to provide hollows over time. The presence of hollows, old logs and dead trees is fundamental for providing habitat, species protection and maintaining overall diversity. This will become increasingly important under a changing climate.

Attempting to maintain the status quo by conserving the current structure and composition of communities in the Glenelg Hopkins region may not be a viable management option in the long term. A shift in management focus towards maximising the resilience of communities and maintaining ecosystem function is required. This approach fits well within a risk management framework because there will always be uncertainty associated with future climate projections. Current condition is likely to be an important predictor of the long-term viability of a community, with those in better condition more resilient to change in the short term, and more adaptable in the long term due to their greater genetic, floristic and structural diversity.

For future revegetation projects a shift in focus is required from planting species specific to the Glenelg Hopkins region to planting species or ecotypes expected to be more tolerant of new conditions. Additional research is required to support this change.

 

[i] W Steffen, A Burbridge, L Hughes, R Kitching, D Lindenmayer, W Musgrave, M Stafford Smith, P Werner, Australia’s biodiversity and climate change: summary for policy makers, 2009.

[ii]  J Memmott, PG Craze, NM Waser, MV Price, Global warming and the disruption of plant-pollinator interactions, Ecology Letters 10, 710-717, 2007.

[iii] NJ Holbrook and J Johnson, Australia’s marine biodiversity and resources in a changing climate: a review of impacts and adaptation 2009–2012, National Climate Change Adaptation Research Facility, Gold Coast, 2012.

[iv] C Parmesan, G Yohe, A globally coherent fingerprint of climate change impacts across natural systems, Nature 421, 37–42, 2003.

[v] VAJ Doerr, KJ Williams, M Drielsma, ED Doerr, J Love, A Langston, S Low Choy, G Manion, EM Cawsey, HM McInnes, T Javanovic, D Crawfors, M Austin, S Ferrier, Designing landscapes for biodiversity under climate change, National Climate Change Adaptation Research Facility, Gold Coast, 2013.

[vi] VAJ Doerr, KJ Williams, M Drielsma, ED Doerr, J Love, A Langston, S Low Choy, G Manion, EM Cawsey, HM McInnes, T Javanovic, D Crawfors, M Austin, S Ferrier, Designing landscapes for biodiversity under climate change, National Climate Change Adaptation Research Facility, Gold Coast, 2013.

[vii] TH Booth, KJ Williams, Developing biodiverse plantings suitable for changing climatic conditions 1: underpinning scientific methods, Ecological Management and Restoration, vol 13, 2012

[viii] TH Booth, KJ Williams, Developing biodiverse plantings suitable for changing climatic conditions 1: underpinning scientific methods, Ecological Management and Restoration, vol 13, 2012