As the climate continues to change, entire ecosystems are becoming increasingly threatened by shifting abiotic conditions. Many communities of plants and animals that are part of these threatened ecosystems have a limited ability to disperse to more amenable habitats. While climate change may make some sites uninhabitable for a given community, it can also make other sites more suitable. Boreal forests are a prime example of how climate change is irreparably damaging ecosystems (and biomes). Increasing temperatures are melting permafrost resulting in ‘drunken forests’ and vast releases of methane and CO2. Higher temperatures can also result in forest fires, drought, and outbreaks of pest insects. Can anything be done about this?
While climate change may make some sites uninhabitable by a given community it can also make other sites more habitable. Traditionally when a charismatic species becomes threatened one option is to translocate it to another habitat, but this does not preserve all of the complex community interactions that make that species and the ecosystem it was part of special. So what happens to the populations of plants and animals with insurmountable barriers to dispersal? What happens to the unique soil fauna and flora? Without intervention many of these less mobile organisms may die-off in places or potentially go extinct altogether. Ecosystem-scale translocation (EST) could be a useful tool in our mitigation toolkit.
EST involves moving a large sub-set of an ecosystem, including the topsoil, plants, invertebrates, and other animals that inhabit it. In the mining industry this is known as vegetation direct transfer (VDT) and involves using diggers and trucks to move 2-3m² ‘sods’ consisting of the top 30cm of topsoil with plants and small animals. It used as an ecological restoration tool to save sections of an ecosystem prior to mining so they can be put back after mining has been completed. Importantly, this topsoil also contains much of the bacteria and fungi that are essential to plant growth. The plants that are growing in the sods can also contain communities of epiphytes, invertebrates, and algae.
A paper published by Boyer et. al. this year touts EST as way of relocating parts of threatened ecosystems from their current climatically unstable sites to more stable ones. Boyer also discusses it in a blog post in ‘The Conversation’ from his experience at the Soild Energy Stockton coal mine in New Zealand. As the authors point out the major hurdle to overcome is in selecting the ideal receptors sites for the translocation. However, using existing data and GIS they were able to identify countries that contain large areas of potential source (sites under threat by climate change) and corresponding suitable receptor sites where EST could be employed.
The other key limitation highlighted is the high cost of this method. Despite these limitations, the technique has been used widely with success in the mining industry. The authors list no less than 26 examples of projects where it has been used successfully in Germany, United States, United Kingdom, China, and New Zealand. What the authors fail to mention is that in all of these cases the habitat types for VDT contained mainly low vegetation, such as grasslands and shrublands. As these guidelines for mine rehabilitation in New Zealand show, where trees are present, they must be felled before sods can be translocated. It seems that this technique cannot be used to transfer segments of forest.
VDT/EST has only been found to be effective for saving some habitat types. Many of the countries that were identified as ideal candidates to trial EST actually contain large tracts of forests which are not suitable for EST, and this should have been discussed in Boyer et. al.’s paper and included in their GIS model.
So, can we save entire ecosystems from climate change by simply moving them? The simple answer is maybe in some cases, but not for most ecosystems.
The author Ross Carter-Brown is a postgraduate student in the Master of Science taught at Lincoln University. He wrote this article as part of her assessment for ECOL 608 Research Methods in Ecology.