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Safeguarding Extinct Plants In Ex Situ Collections

Volume 7 Number 1 - January 2010
Rafael Govaerts

Ex situ collections may provide the only lifeline for an increasing number of species – but are we taking the necessary steps to ensure their survival?

Background

For threatened plants, ex situ conservation is generally considered to be a temporary or transitional stage in a long-term strategy aimed at achieving conservation in situ. However, for those taxa that are extinct in the wild, ex situ conservation in living plant collections provides the only lifeline. For such plants, their natural habitat may have entirely disappeared or their seeds cannot be stored.

Since the late 1980's, I have maintained a database of those taxa that are documented to be extinct (EX) or extinct in the wild (EW) as defined by IUCN (2001). This is by no means a complete list as only published documented cases are included. This is to prevent the inclusion of species such as Tecophilaea cyanocrocus (Watson, 2008) which was listed as extinct until extensive in situ surveys were conducted and the species was rediscovered in great abundance.

Of the 844 extinct taxa in the database, 72 are listed as still being present in cultivation. Having monitored these taxa for more than 20 years, I have been surprised at the lack of focus on these taxa and am concerned about their continued long-term survival. I have also identified 39 taxa that used to be in cultivation but have now apparently disappeared altogether. The reasons for the apparent lack of interest is possibly because conservation conventions and infrastructure have largely used ex situ collections as a means to support in situ conservation rather than as a conservation focus in itself. For threatened plants that survive in situ, this is of course the right strategy. However this can mean that those species that are extinct in the wild are not given the attention they deserve.

“I am concerned by the lack of focus on conserving plants that are extinct in the wild”

Although Target 8 of the Global Strategy for Plant Conservation (GSPC) focuses on ex situ conservation, no specific measures or infrastructure have been established to deal with the specific vulnerabilities of EW plants in cultivation. The only targeted publication to date was one published by IUCN/BGCI in 1989. As we are only dealing with a small number of taxa, I believe that with little effort an effective infrastructure could be set up to ensure the long-term survival of EW taxa in ex situ collections. It is especially important for these taxa to conserve all the surviving genetic diversity- in other words - every individual counts.

“When dealing with nearly extinct taxa, every individual counts”

Over the years I have identified a range of problems faced by extinct taxa. These are listed below, together with some possible solutions. Although many of the examples are from the Royal Botanic Gardens (RBG), Kew (my home institutions), this is not because the situation here is particularly bad, but rather that it is representative of the general situation. It should also be noted that many extinct taxa are being grown at RBG Kew and the gardens have had notable success in saving a number of taxa from certain extinction.

1. Trophy plants

The best example in this category is undoubtedly Encephalartos woodii which is widespread in collections (11 are listed in the BGCI PlantSearch database). Although individual trophy plants are normally well taken care of, little effort may be made to propagate them. After all if you have more than one in your collection you can no longer tell the visiting public that it is the only surviving specimen. The danger of course is that when the one individual dies, none are left. Encephalartos is after all relatively easy to propagate from leaf-cuttings. There is also the option of multiplying the plant by micropropagation, with the view of potentially creating female specimens in the future. The quest for the creation of a female specimen has for the moment been taken up by a commercial company (Hurter, 2008), possibly due to the limited resources available in many botanic gardens. E. relictus is in an identical situation to E. woodii. Although it is less of an icon, there is still the need for a well organised strategy to be in place to ensure the survival of this taxon.

Trophy plants, by their very nature, are especially vulnerable to theft. With specimens of E. woodii being valued at $20,000 on the open market, it is not surprising that plants are regularly stolen from collections.

Although trophy plants can be useful in promoting awareness amongst the public of plant extinction risks, it is important that the bigger picture is not forgotten, and efforts are made to continue propagating the taxon. Of course only one individual need be put on display to maintain the power of its story.

2. Horticultural fashions

Some of the extinct plants in cultivation are widely grown and easy to cultivate, such as Tulipa sprengeri. The original plant was collected in Amasya, Turkey and it has been maintained in horticulture and botanic gardens ever since (18 gardens are listed in BGCI’s PlantSearch database). As it is commonly seen in gardens, is easy to cultivate and often naturalises from seed, it may not be considered important and may end up in a forgotten corner somewhere. The danger is that because of this lack of vigilance, the specimens may be accidentally destroyed. Tulips suffer from a multitude of diseases so it is a distinct possibility that a disease could appear and destroy all plants in a given locality in a short period of time. As mentioned before, it is very important for the survival of a species to maintain all existing diversity, even for a common taxon.

The greatest danger of relying on horticulture for long-term survival is of course that fashions change and the plant may become unpopular. The species may then disappear from horticulture altogether, as is the case with Hindsia violacea, now thought to be completely extinct.

“As fashions change, rare species may disappear from horticulture altogether”

Conservation of extinct plants should remain immune from fashion and each species, even each individual, should be valued equally. For a species like T. sprengeri, seed banking would probably be the best option for long term conservation. Unfortunately however, many seed banks have a policy of storing only seeds collected from wild origin plants – thus excluding species that are extinct in the wild. It is good to know that the Millennium Seed Bank at Wakehurst Place has recently relaxed its rules and now has a programme of collecting seeds from threatened plants in cultivation.

3. Project – the dirty word

Much conservation work is funding as projects. The first problem with this is that projects are by definition short-term, mostly 3-5 years. This may be the right strategy for many aspects of plant conservation but is definitely inadequate for the long-term survival of species. Kew has been involved in saving a number of species before they became extinct in the wild. Typically these species are a priority for a few years, but once the initial rescue project is completed, resources are focussed elsewhere and the species’ survival prospects decline. Commidendrum rotundifolium for example was discovered as a single surviving tree in 1982. Thanks to the skills of Kew's micropropagation unit, the species was successfully propagated. In 1986 the single wild tree was destroyed by a severe gale and by 1991 the last remaining plant at Kew Gardens had died as well. Now only a few trees remain in cultivation on St. Helena seemingly unable to produce viable seeds.

The defined nature of projects can also pose a problem, with activities lying outside such projects not being supported. One such example is that of Anthurium leuconeurum. This species was only collected once in Chiapas, Mexico and has not been seen since. Although it is widespread in cultivation, until 1999 it had never been recorded to produce seeds (Govaerts & Frodin, 2002). However, once seeds were produced, no institution could be identified with a relevant conservation project into which continued work on this taxon could fit. Consequently, an opportunity was missed to take the survival of this species forward with a possible view to reintroduce it into the wild.

4. Refocus and restructuring

These are words commonly used these days, all too frequently as a euphemism for financial and staff cuts. Such cuts often go unnoticed and may result in extinct plant material dying or being destroyed. One such example is Bromus eburonensis, the only Belgian endemic (except for perhaps some microspecies like Rubus prei). It, together with the near-endemic B. bromoideus and artificial crosses used in research experiments were for many decades cultivated at the Botanical Garden of the University of Liège. However, when the activities were scaled down and the area transformed to a public park, the plants disappeared as well.

This situation could be avoided if an international infrastructure were to be set up to track which institutions care for extinct taxa, and identifying when they are no longer able to continue to do so. A simple allocation of responsibilities and annual reporting on the state of health of extinct taxa might be trialled.

The bottom line of course is that sufficient funding should be made available for institutions to continue to maintain important collections of threatened plants.

5. Knowledge is survival

Even though we live in the age of instant access to information and most botanic gardens have their collections databased, with the possibility to include IUCN red list categories, this information does not always get to the horticulturalists and gardeners that look after the actual plants. A recent example is that of Aechmea serrata. The Bromeliad living collection, as well as the electronic data attached to it, is very well managed at Kew Gardens. Nevertheless the Conservation category for this taxon was blank. So the person in charge was not aware of the importance of this plant and the possible conservation implications.

While it is important for databases to be more closely linked so that relevant information is always available, a more practical, immediate action could be to use red-coloured labels for extinct and critically endangered plants. In this way, the information is not lost when staff change or temporary staff take over the care of these valuable plants.

Conclusion

After monitoring extinct plants in cultivation for more than twenty years, I'm afraid the conclusion must still be that most are not yet safe from accidental loss. The main solution must certainly be better access to information by linking garden databases directly to the IUCN red list (this can be done through BGCI’s PlantSearch database) as well as appropriate labelling. Also better communication between botanic gardens and conservation organisations should be pursued by creating a framework that monitors, either formally or informally, extinct plants in cultivation. This could be strengthened by providing a protocol to which participating gardens would commit.

Saving the last individual from extinction can be very expensive - efforts should be made to ensure this does not need to happen again and again.

References

BGCI Plant Search, published on the internet [http://www.bgci.org/plant_search.php]. accessed September 2009.

Govaerts, R. and Frodin, D.G. 2002. World Checklist and Bibliography of Araceae (and Acoraceae). 560 pp. The Board of Trustees of the Royal Botanic Gardens, Kew.

Hurter, M. 2008. The different Encephalartos woodii plants. Encephalartos 94: 31-35.

IUCN. 2001. 2001 IUCN Red List Categories and Criteria version 3.1. [http://www.iucnredlist.org/static/categories_criteria_3_1]

IUCN Botanic Gardens Conservation Secretariat. 1989. Extinct plant species of the world.

Watson, J.M. 2008. Tecophilaea cyanocrocus: demolishing bad science. Herbertia 62: 209-240.

Rafael Govaerts
World Checklist Programme Herbarium, Library, Art and Archives
RBG Kew, TW9 3AE, UK
Email: R.Govaerts@kew.org