Ex situ conservation in botanical gardens in theory and practice

Three papers on the role of botanic gardens in ex situ conservation have recently come across my desk, one of them a meta-level thing, the other two more fine-grained. I think it may be worth discussing them all together.

Science had a longish piece by Elizabeth Pennisi out in the 5 October edition entitled “Tending the Global Garden.” ((Pennisi E (2010). Tending the global garden. Science (New York, N.Y.), 329 (5997), 1274-7 PMID: 20829463)) It reviewed how botanic gardens, “[i]n addition to leading efforts to tally the world’s plants,” have also “made progress in setting up seed banks and native plant collections. In some cases, they have even reintroduced endangered species back into native habitats.” This has been rather a change of emphasis for botanic gardens, which had been “somewhat resistant to conservation as a main activity,” according to the retired president of the Missouri Botanical Garden, Peter Raven.

A turning point came in 1999, at the International Botanical Congress in St. Louis. There, Raven appealed to the broader botanical community and was cheered when he called for a global initiative to save plants. By 2002, botanists, policymakers, and other interested parties had come up with the Global Strategy for Plant Conservation: 16 specific targets or goals ranging from a worldwide list of plants to conserving plants and educating the public. That same year, national delegates approved incorporating the strategy as part of the CBD.

One result is the recently unveiled master list of the world’s plant names, surely a major achievement. However, a global Red List of threatened plants is lagging behind, which is affecting other goals of the Global Strategy for Plant Conservation, such as 60% of threatened plants to be conserved ex situ, and 10% of threatened species to have recovery and restoration programmes.

There’s been modest progress toward both goals. In 2002, just an estimated 15% of threatened plant species had been incorporated into in these ex situ collections, with only 2% in recovery projects. By 2007, the numbers were 35% and 5%, respectively, according to the Convention on Biological Diversity Plant Conservation Report assessing progress on the initiative.

That hasn’t stopped botanists fiddling with the targets:

That the native habitats of many plants are becoming unsuitable homes has made ex situ collection a higher priority, say conservation scientists. They are therefore updating their global plant conservation strategy and have proposed a 2020 goal of having 75%, instead of 60%, of endangered plants in protective programs, and 20%, not 10%, targeted for recovery and restoration. But… the lack of a global Red List for plants makes it difficult to know how accurate these numbers are.

Funding is, of course, the perennial problem.

In the developing world, where botanic gardens struggle to get any funding, “many governments are beginning to focus in on one priority, poverty,” says Stella Simiyu of BGCI. She argues that to stay relevant and survive, botanic gardens in such places will need to focus on facilitating the sustainable use of plants, particularly of medicinal plants, which are in high demand and have dwindling numbers. They will need to partner with government and nongovernmental agencies to coordinate education programs that help promote judicious use or protection of rare resources. “Typically, botanic gardens don’t work like that,” says Simiyu.

Neither do genebanks, one is tempted to add. Pity that crop wild relatives were not mentioned, for example in the context of the work of the Millennium Seed Bank at Kew. That would surely be another way for botanic gardens to show their relevance to the development imperative.

After that romp through the upper reaches of policy, it was nice to get down and dirty. First up was a paper on Vavilovia, a rare(ish)wild relative of the pea, in GRACE. ((Akopian, J., Sarukhanyan, N., Gabrielyan, I., Vanyan, A., Mikić, A., Smýkal, P., Kenicer, G., Vishnyakova, M., Sinjushin, A., Demidenko, N., & Ambrose, M. (2010). Reports on establishing an ex situ site for ‘beautiful’ vavilovia (Vavilovia formosa) in Armenia Genetic Resources and Crop Evolution DOI: 10.1007/s10722-010-9606-0)) It has already been deconstructed over at Vaviblog, but I bring it up here because it shows a botanical garden in hot ex situ conservation action. It turns out that…

…Vavilovia has periodically been grown in the research and display plot Flora and Vegetation of Armenia in the Yerevan Botanic Garden since 1940. This living exhibition reflects the botanical diversity of the country. The creation of the alpine rock habitat was preceded by a period of long-term research into the biology and ecology of the alpine plants, which facilitated their introduction into relatively low-altitude cultivation from their native 2,800–3,500 m.

A nice idea for education and public awareness, but it’s been a struggle for the Vavilovia to acclimitize, and it’s still not clear that it will be possible to establish a population. If it does indeed turn out to be possible, the third paper in this botanic gardens trifecta will come into play. ((Enßlin, A., Sandner, T., & Matthies, D. (2010). Consequences of ex situ cultivation of plants: Genetic diversity, fitness and adaptation of the monocarpic Cynoglossum officinale L. in botanic gardens Biological Conservation DOI: 10.1016/j.biocon.2010.09.001))

This compared populations of the rare perennial Cynoglossum officinale kept in various German botanical gardens with natural populations. Although average levels of genetic diversity were similar in the two kinds of populations, clear evidence was found of genetic change, with seed dormancy lower in the botanic garden populations and contrasting responses to high nutrient levels. This was considered to be probably due to “unconscious selection by gardeners” over in some cases decades of continuous cultivation.

The changes observed are similar to those found in crop plants in response to cultivation… Such adaptations to cultivation could be maladaptive in nature.

So, even if botanic gardens manage to hit the 75% target of endangered plants in protective programs, they’ll have to be careful that they use the right material in trying to meet the 20% target for recovery and restoration. Probably best to go back to the seed that was collected from the original natural population and stored in a genebank, rather than seed from things like the Flora and Vegetation of Armenia plot, as wonderful as that may be for educational purposes:

…botanic gardens should pay more attention to the problem of potential genetic changes and avoid as far as possible practices that result in strong selection, in particular for species with short generation times.