Last week, Associate Editor, Pieter De Frenne commented on the article Tiny niches and translocations: the challenge of identifying suitable recipient sites for small and immobile species. By Brooker et al. Now the authors share their thoughts on the well-debated topic of translocation.
Climate change and its effects on some species has sparked a debate among scientists about whether moving species to more suitable places is the correct thing to do. Called translocation, it sees plants or animals shifted in a bid to conserve them and the debate centres on the morality of this intervention and if we should let nature run its course.
There are concerns that this approach has risk attached to it. Things could go wrong at the donor site as scientists may be forced to move individuals from populations of plants, animals or lichens which are already threatened.
Or it could go wrong at the recipient site as new species – both intentionally and as piggy-backers – would be introduced to new environments. And we all know how well that can work out e.g. when introduced species become invasive.
You might think there is lots of useful information out there to guide this technique. Many translocation trials have been undertaken, but until recently these were often disconnected from long-term monitoring so it was hard to know why – or even if– they had been successful.
And while more robust trials have recently been undertaken they tend to use species that are mobile – at a small scale at least. If you put such an organism in roughly the right spot, it has a chance to search around for conditions which suit.
We felt the challenge of successful translocation would be much greater for immobile species, especially those from harsher environments such as alpine, arctic, or desert ecosystems.
The problem of immobility is obvious: where you get put is where you have to stay – and if it’s not perfect; that’s too bad. In these situations, small distances can mean big changes in conditions. If you’re out in your site location by just a few centimetres, it could make all the difference between life and death.
In our new paper, Tiny niches and translocations: The challenge of identifying suitable recipient sites for small immobile species we describe a study which examined this issue. We studied alpine lichen Flavocetraria nivalis, sometimes called the Crinkled Snow Lichen. Using a survey of sites in the Cairngorms, we developed a model which attempted to predict the location of suitable sites.
We then moved lichens within a focal study site, and examined if the survey-based model allowed us to predict the survival of our lichen transplants.
Initially, our models for predicting lichen survival had room for improvement, but they improved in two ways:
Firstly, model fit improved – it took a long time for lichens to die, and the distribution of surviving lichens was somewhat mismatched with the location of suitable conditions. This demonstrates the importance of long-term monitoring.
Secondly, our models could be improved by including local-scale measures of environmental conditions. In particular we included data from data loggers close to the lichens, indicating the importance of local conditions in determining whether or not our transplants survived.
Lessons learned are that it is tricky to move immobile species in severe environments as they have to be placed in just the right spot. Models can help and these can be improved by local-scale data, but it’s probably best to combine modelling and expert knowledge.
Also, expect mortality. This latter point challenges the use of assisted colonisation as a last-ditch conservation action, or at least the notion of what that might look like. If species are from harsh environments and are immobile, you might need many more transplants than under other circumstances.
We feel more experimental studies like this are needed to help us adapt the approach we take to assisted colonisation to the characteristics of the environment and species involved – should we choose to do it at all.
Read the full article, Tiny niches and translocations: the challenge of identifying suitable recipient sites for small and immobile species in Journal of Applied Ecology and share your thoughts in the comments below.
Read the Associate Editor’s post on this article here.