Incorporating climate projections into conservation planning for the future of the lowland native grasslands of Tasmania, Australia

Background/Question/Methods

The long-term viability of highly fragmented threatened communities depends on the climate remaining suitable into the future. Changing climatic suitability may lead to shifts in the distribution of some or all species, resulting in an altered community with a different composition, structure and, possibly, function.

We identify possible options for managing threatened communities under climate change, using the Lowland Grassland community (LNGT) in Tasmania, Australia, as a case study. We test whether future climate conditions are likely to remain suitable for the lowland grassland community. We do this by modelling the current and future climatic suitability for the community as a whole, for the structurally dominant species, and for the areas that are currently in the best condition. We use a correlative species distribution model (Maxent) and climate projections from six dynamically downscaled climate models to project the change in climatic suitability for this community from the present to the end of the century. 

Results/Conclusions

The current distribution of the LNGT is already highly restricted, and the projections suggest it will contract substantially over the next century due to climate change. The projected contraction is so substantial that it is unlikely that the grassland community will continue in its current form.

However, when the dominant species, Poa labillardierei and Themeda triandra, are modelled separately, climatically suitable areas are projected to persist within the current distribution. This provides options for managing the community, but only if the dynamic nature of changing communities under climate change is acknowledged. Current planning and policy frameworks are unable to do so, since they aim to maintain the current composition and structure. Areas of the best condition are likely to be the most resilient to change and the most likely to maintain function under changing climatic conditions. These areas should be the focus of conservation efforts.