Species Translocations And Environmental Change: A Useful Tool For Biodiversity Conservation?

Published on 11 June 2010 in Ecosystems and biodiversity

Introduction

There is considerable evidence that as climate change progresses species are moving in order to track their preferred climate. However, not all species are able to undertake this “climate tracking”. In the case of plants, for example, some species produce very few, large seeds that tend to fall close to the parent. In the case of birds, in some species the offspring take a long time to reach breeding age, and then establish nests close to the nest in which they were raised. In both cases, the rate of spread of the species can be very low.

In addition to their ecology, habitat fragmentation can also be an important factor limiting the rate of species movement. Some species are dependent upon particular habitats – they cannot survive or reproduce outside of them. If there is not suitable habitat in the right place the species may be trapped and unable to move, perhaps forced to extinction as the climate changes around it.

Because of the possibility of species becoming stranded in this way, conservationists and researchers have started to discuss the potential to actively move - or translocate - species in order to either help them overcome dispersal barriers, or to establish them in sites that will be suitable in a future climate. However, this proposed conservation tool is also highly controversial. While translocations within a species’ current range are commonly used and widely accepted, it is felt that there may be particular problems associated with moving species’ outside of their range – a type of translocation which has been called assisted colonisation or assisted migration.

Key Points

Ongoing debate about the use of assisted colonisation is fuelled by a lack of information. Even for the more common technique of translocation within a species’ range, a recent review concluded that there are very few scientifically-rigorous assessments of its application. If we can address these uncertainties then we can assess whether translocation is a useful tool for conserving biodiversity during climate change.

This possible application of species translocations is, therefore, a clear target for research. Key questions that need addressing include:

• Can we predict where suitable sites for the species will occur in the future?
• How should we select material (e.g. individuals or seeds) for translocation from existing populations?
• How great are the risks of moving a species outside of its current range?
• What are the best techniques for moving particular species?
• How can we assess and manage any important interactions between species?

Although any one study will only be able to address a few of the considerable number of relevant questions, at present any scientifically-rigorous study will provide much-needed information.

 

Research Undertaken

The Macaulay Land Use Research Institute and Scottish Natural Heritage are undertaking a co-funded project “Feasibility study: translocation of species for the establishment or protection of populations in northerly and/or montane environments”. The first stage of this project has involved a substantial literature review. This has enabled us to define clearly the main areas of scientific uncertainty associated with assisted colonisation, and with translocation techniques in general. The review is currently in the process of being published by SNH.

The review explored the possible use of assisted colonisation within Scotland for three species groups: lichens and bryophytes, vascular plants, and terrestrial invertebrates. It considered the practicalities and risks of moving species from these groups into sites that might be considered climatically suitable in the future. One major risk frequently discussed is the possibility of translocated species becoming invasive in recipient sites. The review concluded that this was very unlikely for these these types of species within Scotland: likely targets would be relatively non-aggressive rare or alpine species, and movements would be over comparatively short distances. Overall our literature review agreed with previous reviews in concluding that although there was considerable debate there was very little in the way of empirical evidence to help inform decision making.

The next stage of the project – to be implemented in 2010 – is the establishment of field trials. The key question to be addressed by the field trials is: can we predict the location of suitable sites for receiving translocations both within and outside of a species’ current range? The response of species’ ranges to climate change, i.e. how the distribution of a species might move to track climatic conditions, has generally been modelled using climate envelope models. In essence, these assume a direct link between the range of a species and the climate conditions across that range. However, these models commonly work at a very large spatial scale. Consequently, although they might predict that suitable climatic conditions will occur within a 10 x 10 km area, the problem then is down-scaling that prediction to identify suitable sites on, for example, a particular mountainside.

Our field trial, focusing on the alpine lichen Flavocetraria nivalis in the Cairngorms, will assess the ways in which we might downscale climate envelope models. As part of this study we will also consider the extent to which the survival and growth of the lichen is dependent on having the right surrounding plant community as well as the right climatic conditions.

Importantly we are using this new study as an opportunity to develop links to other relevant research on species translocations, including work being undertaken at the University of Aberdeen and at the Royal Botanic Gardens Edinburgh.

Policy Implications

The information provided by our work will be of direct use to conservation agencies such as SNH, who are tasked with conserving biodiversity during a period of substantial and rapid climatic and land use change. Improving our knowledge of this technique will help to resolve some of the current debate about whether or not it is a useful conservation tool. If it is judged to be a useful and applicable technique, even under a limited set of circumstances, then it could be applied as part of the suite of conservation measures that will be necessary to conserve biodiversity during climate change.

Author

Dr Rob Brooker r.brooker@macaulay.ac.uk

Topics

Ecosystems and biodiversity

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