Glen: G’day and welcome to CSIROpod, I’m Glen Paul.
Conserving biodiversity under climate change is challenging the way scientists think and radical plans, such as the relocation of threatened species, is now a hotly debated topic. In a paper published recently in the journal Nature Climate Change CSIRO and University of Queensland researchers have put forward what they see as a no nonsense decision framework for determining when, if ever, to move species in the face of climate change.
Joining me online to discuss it is Doctor Tara Martin from CSIRO Ecosystem Sciences. I can see, Tara, why this topic would be generating discussion because if relocation went wrong potentially you could create a pest problem at the new target site. How strong is this argument?
Dr Tara Martin: This has been one of the main controversies about this adaptation strategy. We have a long legacy of moving species around the planet and many examples of where that hasn’t gone very well, particularly in Australia we have many examples which are causing us to spend enormous amounts of money now managing the threats posed by those invasive species. So for good reason people are hesitant of this idea of moving species that are threatened by climate change but there are some key points that need to be made of why this is potentially the only feasible action for some species. For species which are climate threatened and have no capacity to adapt because of the pace of climate change - for example, species that occur on the tops of mountains, some of our coral species or species which aren’t able to move because we’ve modified the habitats around where they’re currently located – for those species their only option may be intervention.
Glen: How do you establish that a species doesn’t have the capacity to just adapt to climate change if left alone in that current location?
Dr Tara Martin: That is a really good question and that’s something that many scientists are trying to work out right now through quite extensive of modelling of the requirements for species in terms of their habitat needs, but also their physiological responses to changes in climate parameters. That’s something that we’re working on and we have a fairly good idea of which species may be able to adapt versus which ones are unlikely to be able to adapt.
Glen: What checklist would you have to run through before considering relocating a species?
Dr Tara Martin: There are many things and this is what our framework tries to set out. The first thing that we need to understand is what is the impact of climate change on that species. We have a lot of different projections, climate projections that we use to get some idea of the variation that might be expected in this species ability to adapt under future climates. The first thing is to try and characterise the uncertainty or, in other words, how certain we are that climate change is the key driving factor for the decline in that species.
There are also a lot of other threats that are occurring at the same time as climate change. We need to be, first of all; sure that climate is the main driving factor of the decline in the species. The next thing we need to consider is what is the population size of that species and what is the ability of that species to recover if it was moved to a new location. Some species have very high growth rates, whereas others have quite low growth rates and we need to know something about the actual demographics of that particular species and the characteristics of that species to withstand a translocation. We also need to think about what is the potential of that species to become invasive or problematic in that recipient site which is the main argument, the idea that the species could become invasive is the main argument that people through up against this idea of moving species.
We can look at the species ability to adapt in this new environment, what potential interactions the species will have with other species that are important in this environment, is the species likely to disrupt important ecosystem processes and then finally it comes down to a value judgement about how much do people value that particular species? This strategy won’t be something that is used for most climate threatened species, it will be used sparingly and it will be used for things that people really care about.
Glen: Absolutely. Obviously relocations cost money and its unlikely there will be enough to go around so who then does decide which species is more valuable in terms of saving from extinction than another?
Dr Tara Martin: This is a very tough question. There’s actually a lot of research that has gone into what species get listed, for example, on our endangered species list versus those that don’t. There’s quite a huge taxonomic discrepancy in that we’ve got a lot of what we call higher order taxa listed than lower order fungi, bacteria etc listed. As humans we tend to value vertebrates more so than many of the lower order taxa. Who decides? It’s not an easy question but we already have a fair indication of what people tend to value. If, for example, we are faced with a situation of saving koala’s or saving a particular species of mangrove snail it’s probably quite clear where people would invest in that choice.
Glen: So cute, cuddly koalas. We do hear stories all the time about managed relocations due to threats like overgrazing or dams being built. What is the big difference here between that and moving species due to the threat of climate change?
Dr Tara Martin: Yes, we’re very familiar with translocations. In fact in Australia we’ve moved over 42 different species to various locations throughout as a result of different threats like overgrazing, predation by feral cats and foxes have also been one of the key reasons for translocating species. It’s something that we’re very familiar with, it’s a really important tool in our toolbox for managing species but the difference here is we’re talking about moving species to locations where they’ve potentially never occurred before. Most translocations in the past have been moving species to areas within their range.
Range may have contracted over time because of human threats however the translocation is generally moving it to another place it was formerly established. In this case we’re talking about moving things to areas where they may have never occurred before, certainly in terms of our human record. That’s the thing that I think worries people most, we’re potentially introducing species to quite novel habitats.
Glen: What if you found fossil evidence that said the species did once populate an area, would it therefore then be OK to return them there now?
Dr Tara Martin: That’s a good question and there’s an example where that’s been the case, the Mountain Pygmy Possum has been talked about as a candidate for managed relocation. It thrives in high altitude snow fields down south for thousands of years and it hibernates in deep snow during the winter. Recently the snow melt has occurred earlier in the season and it’s exposing these Pygmy Possums to harsher conditions and also exposing them at a time when food resources are low.
There’s been a lot of talk about the need to potentially move these species to areas where there would be better habitat and a more climatically favourable habitat. The issue that they’ve recently found is that they thought that this possum only occurred at high altitudes but fossil evidence has now shown that this possum was quite widespread at lower altitudes throughout forest and rainforest. The reason why they think maybe the Mountain Pygmy Possum’s current distribution has been focused in these high altitude areas is because it moved to higher altitude to evade predation from cats and foxes. I think understanding that early fossil record is actually really important for tempering arguments about where species are meant to be because often where they occur now is as the result of other human threats, not necessarily natural processes.
Glen: Right, so the Mountain Pygmy Possum is a candidate. Have there been any species relocated to date as a result of climate change?
Dr Tara Martin: Not in Australia. There’s been several species overseas that have been moved, species of butterfly in particular. In Australia there hasn’t been any species moved primarily because of climate change but there have been many species that have been moved because of other threats.
Glen: What areas of Australia are showing up in modelling as being under threat?
Dr Tara Martin: Quite vast areas, in fact. Our modelling suggests that many parts of Australia will undergo quite substantial changes in terms of their composition of plants and animals. There’s virtually no area of Australia that will be untouched by climate change, but we have a good indication now of which areas will be under higher levels of stress and those are the areas where we can start to think about which species occur there, which ones are likely to be able to adapt naturally and which ones will be candidates for translocation.
Glen: When do you think we’ll start to see relocation seriously being considered?
Dr Tara Martin: I think right now, there’s several species that people are working with right now that are candidates and it’s a matter of getting our regulatory framework and our policies in place that we can accommodate mandatory location. At the moment the translocation protocols do not accommodate moving species because of climate change, there’s some amendments that need to be made before people will be able to use this as a management strategy within Australia.
Glen: It’s a tricky topic, Tara, but it certainly would be nice to keep species alive for future generations. Thank you very much for talking to me about it today.
Dr Tara Martin: Thank you.
Glen: Doctor Tara Martin, for more information find us online at www.csiro.au and you can like us on Facebook or follow us on Twitter at csironews.