This article from the Canadian based magazine called The Walrus got me thinking. We know that climate science predicts that some species will migrate ‘uphill’ to try and find the climatic conditions they can flourish in as the temperature warms. This could see some sub alpine and alpine species becoming extinct as they face stiff competition from new species moving into their traditional range and with Australia only having mountains of low elevation, some species could simply be pushed off the top of the ranges.
There are various research projects looking at how climate change is likely to impact on native species in the Alps. The best chance we have to save alpine species in the wild is to reduce future warming through meaningful mitigation efforts (ie we need to stop polluting the atmosphere with greenhouse gases). But what about the warming that has already happened, and the future warming we are locked into as a result of previous carbon which has been released into the atmosphere? How much ‘room’ do we have for species that are already existing towards the top of their range, with limited space to migrate upwards?
This story from Canada raises the notion of ‘assisted migration’ for vegetation.
Some key points from the story:
- A study by the United States Forest Service into the whitebark pine predicts that 97% of it’s current distribution will be too hot for the species after 2100, leaving little hope for the slow-growing tree, which can take up to eighty years to produce large crops of cones. The whitebark is an endangered tree species in Canada
- there is a plan to start to plant whitebark pines as far as 800 kilometres north of their current range, to provide habitats where the species can survive in the wild
- sites for the relocation were identified by looking at climate models. Researchers found nine sites where the pines might thrive in a warming world
- it will take at least another decade before it is clear whether the assisted migration program has worked
Sierra McLane, from the University of British Columbia, who is involved in the project admits that “we’re playing God. This is a very gutsy thing to do.” There are many things that could go wrong (for instance trees transplanted now could die in winters that are colder than they are used to). There is the uncertainty about exactly what is coming in terms of climate change, and the fact that there will be regional variations, so ‘migration’ might work in some areas but not others. Despite extensive modelling, no one really knows what future climates will be like. Temperatures could rise anywhere from one to four degrees celcius by the end of the century in British Columbia, and precipitation could increase by anywhere from 10 to 20% in the same time span. This makes identifying migration sites difficult. There is also the fact that there can be considerable variation in trees of the same species, depending on where they are from. In the Australia high country, with many high elevation species now being geographically isolated from each other, it may be possible that a new location cannot be found for the various seperate communities. With limited alpine country, transplanting species into a new area would simply displace existing communities. The theory of assisted migration doesn’t seem like a viable option for a place like Australia.
Then there is the ‘cane toad’ syndrome: the often unintended consequences that can come from introducing species into new habitats. Most people are aware that radiata pine is an invasive species in a lot of the bush in south east Australia. But native species can be a worse form of invasive species because they may be harder to identify (and hence remove) and may cross breed with local trees, profoundly changing the local species.
And, as the author of the article, Asher Mullard, notes “a more global problem also looms: assisted migration is designed to treat the symptoms of climate change, but not the disease”.
There is no doubt that in an era of climate change and fragmented ecosystems, we will need more, rather than less human intervention in native ecosystems. As a life long advocate for the creation of wild areas, this realisation is not something that makes me happy. Our greatest efforts must be in the realm of mitigation – doing everything in our power to limit current and future warming. We need to consider if our reserve systems are continuous enough to allow ‘natural’ migration of native plant and animal species as the climate warms. But we do also need to consider where we need to intervene to give threatened indigenous species or communities the best chance of continuing to survive in the wild. This may need greater intervention in terms of where we plant or seed trees or release animals.