Conservation ex-situ and translocation of plant material into the wild
In 1992 the Convention on Biological Diversity (CBD) set out with the purpose of halting the worldwide decline of biodiversity, by providing a framework for national governments to create legislation to protect their biodiversity. This was the first step that prompted conservation efforts at a government level through the participating nations. Currently in 2020, nearing the end of the Global Strategy for Plant Conservation (GSPC) and at the separating of the UK from the European Union and break from the EU’s conservation policy, it is an uncertain and exciting time for plant conservation in the UK.
Ex situ conservation defines conservation benefits that occur away from the affected habitat, that contribute toward the preservation of a threatened species. This article reviews the merit of the GSPC, the benefits and the challenges facing ex situ plant conservation.
The GSPC was introduced in 2002, updated in 2010 with targets to be achieved by 2020. The strategy has 16 targets, which aim to reduce plant diversity loss in wild and crop species through measurable actionable targets including the implementation of biosecurity, education and in situ and ex situ conservation procedures. The GSPC is a strong driver behind ex situ conservation in the UK.
The Royal Botanic Garden Edinburgh stores 86% of threatened Scottish species of plants, in response to the GSPC target 8 which states that ‘at least 75% of threatened plants in ex situ collections in the country of origin’. The Royal Botanic garden Kew acted on target 1 of the GSPC, launching ‘the plant list’ in 2010, a precursor to World Flora Online which was launched in 2012. Botanic gardens and academic institutions have been the biggest players in enacting the GSPC targets. Legislation such as that provided by the GSPC, and through it the CBD, is essential for acting bodies to receive funding from government because it provides a way for national governments to fulfil some of the CBD’s conservation goals. The legislation also provides an accessible entry to the CBD for institutions that want to contribute to the conservation of plants, on an international level. The GSPC has succeeded in mobilising the international botanical community around achievable goals. Both Kew and Edinburgh botanical gardens implement the education of the public and future actors in conservation, through the publication of literature, educational programs and ex situ living collections.
Ex situ collections include seed banks, for example the Millennium Seedbank at Kew botanic gardens, London. In 2009 the Millennium Seedbank succeeded in storing all the UK’s native plant species, excepting very rare or hard to store seeds. Sharing of genetic resources around the world can minimise the chance of losing genetic material. In 2015 the International Centre for Agricultural Research in Dry Areas (ICARDA) were the first to withdraw seeds from the Global Seeds Vault in Svalbard. This was to start propagation of replacement seeds for the ICARDA bank, away from Syria, where conflict rendered the gene bank in Tel Hadya, on the outskirts of Aleppo, impossible to access for staff. Ex situ conservation can be defined by splitting it into two actions; insurance and re-establishment. Maintaining an ex situ collection is both insurance against loss and future potential to re-establish a population.
translocation/reintroduction from ex situ collections
The International Union for Conservation of Nature (IUCN) guidelines state that the risk from translocation must balance with the potential conservation benefit. Risks to the translocated plant in short term include predation and exposure, and long term risks include difficulty finding a reproductive partner, lack of suitable pollinators, changing land use, climatic change and subsequent unpredictability in weather patterns.
The IUCN guidelines for conservation define translocation as the ‘human-mediated movement of living organisms from one area, with release in another’ with ‘conservation benefit’. Conservation benefit is an ambiguous term; the IUCN guidelines are not tailored specifically for plants and have to be applicable for a range of species. Conservation benefits of translocation include genetic rescue through introduction of new genotypes to populations with low genetic difference.
Ecological replacement is the ‘intentional movement and release of an organism outside its indigenous range to perform a specific ecological function’, according to the IUCN guidelines. An example of this is the translocation of a keystone species into a habitat to perform the role of another keystone species that was previously lost from the habitat. Ecological replacement at Knepp estate within a large area of fallow uncultivated farmland aided the increase in Nightingale (Luscinia megarhynchos), a species that has seen large declines in the UK. So perhaps by this example, ‘conservation benefit’ can be had through the indirect ‘top down’ management of an ecosystem by ecological replacement. This concept is perhaps more suitable for large animal species. Although by changing an ecosystem or habitat through restoration, bottom up change is just as transformative and could change niches and attract species. This is seen in the restoration of peat bogs by sowing Sphagnum moss under mulch, utilising the absorbent cell structure of the mature moss to prevent drying of the peat which stabilises the habitat.
Risks to ex situ collections and translocation
Contamination of pathogens can occur through the transport of live plant material, in the soil, or on or within seed. Pathogens could be introduced to nurseries, and spread to other conducive hosts, and effect other valuable collections. A pathogen picked up from ex situ cultivation in a nursery environment could infect the plant population at the centre of the ex situ conservation effort, through reintroduction and then spread to other susceptible hosts. Pathogens such as Phytophthora can remain in contaminated soil for long periods of time and infect a wide range of hosts, and potentially cause a lot of damage to the environment. If Phytophthora spreads to a plantation local to the reintroduced area it could cause economic loss for external bodies and defamation for the conservation work and institution undertaking the work. As 2020 is the Food and Agriculture Organisation (FAO) of the United Nations’ year of plant health, it is important to include biosecurity in the discussion.
Non-native invasive species, that proliferate and affect native species such as Rhododendron ponticum, a species which shades out saplings and prevents woodland recruitment in the UK, can be spread through translocation. A similar risk is that plants in ex situ collections can potentially hybridise, corrupting genomes and rendering a collection unsuitable for relocation. A plant grown in a managed ex situ environment may become unsuitable for reintroduction, as it becomes used to richer soil and sheltered propagation. These can be considered pre translocation issues. Post translocation, a plant will need monitoring in the new habitat, which requires money, time and skills depending on the length of the plant’s establishment period. A translocation project that does not have a long-term plan in place may fail, wasting time, energy and resources.
The ethics of translocation could be considered here as humans are assuming ‘god’ role by moving species between habitats. Creating land corridors between current and potentially suitable habitat or addressing current destructive land management practises could be less invasive ways of helping a species in decline.
The climate is predicted to continue changing on its current trajectory and species that have a low resilience to climatic change could be eligible for translocation. This could be impractical for species that are already at the edge of their range or with very restricted habitat. Conserving species in a habitat that has become unsuitable through climate change, could be considered a misuse of resources if there are healthy populations elsewhere in the world. Translocation is not a solution to climate change itself, as the rate of change may be too fast. The process can be expensive and the results are often uncertain.
A simple limitation to translocation and reintroduction is that you need to establish an ex situ collection to accumulate healthy material. This requires skills, infrastructure and funding that some countries or institutions may not have.
Conclusion
In conclusion, ex situ conservation as a safeguard against genetic loss through habitat destruction is an effective way of safeguarding genetic diversity. Risks of pathogen contamination through translocation of living plant material, transferral of non-native weed species, hybridisation and dependence on cultivation are all risks that can be reduced through careful collection management. Ex situ collections should be a supplement to in situ conservation efforts, to act as a support for species and population recovery. Collections will become more and more vital as conflict over land use in face of a rising human population puts pressure on plant populations. Knowledge transfer between institutions, and between countries is vital for effective conservation, which is included within the GSPC framework.
If ex situ conservation is to continue to be enacted effectively by botanic institutions, the GSPC framework should be implemented post 2020. The framework should also focus on the implementation of the goals at national government level, as currently most work toward the goals is implemented by non-governmental and botanic institutions. If the framework for plant conservation is adopted at government level, it would be implemented into other government policy. This is essential for the benefit of plant conservation in a world where climate change is changing ecosystems and global population is set to increase 10% by 2030.
[essay written in February 2018]
