Trends in Plant Science
ReviewSpecial Issue: Plant science research in botanic gardensPerspectives on orchid conservation in botanic gardens
Section snippets
Botanic gardens and conservation
As we face the sixth great extinction event, the question remains of what can be done to arrest the extinction crisis for plants [1]. With over 2500 sites worldwide (see: http://www.bgci.org/), botanic gardens represent the single largest biological institutional capacity, able to deliver effective plant conservation on all continents. But just how well are botanic gardens placed to meet the global extinction crisis? Are there models that demonstrate how to link ex situ conservation collections
Orchids as a scientific focus plant group in botanic gardens
With an estimated 25 000 species, orchids are the most species-rich of all angiosperm families [2]. They are found on all inhabited continents and are symbolic of the conservation crisis facing global plant life [3], with more orchid species listed as threatened on the International Union for Conservation of Nature (IUCN) Red List than species from any other plant family [4].
Threats to orchid populations include many of the major hazards facing plant life in general, such as overexploitation,
Pollination ecology
Since Darwin ignited world interest in orchid pollination [8], there is a growing body of literature showing how diversification of the family might be linked to pollinator specialization [9]. No other plant family engages in such an array of pollination syndromes. Rodents to birds, food rewards (oils to nectar), food and nest-site deception and a variety of mimicry systems ensure pollination success in orchids [10]. However, it is in the mechanism of sexual deception where orchids excel,
Mycorrhizal biology
Orchid-mycorrhizal biology has a long scientific history beginning in the 19th century, with several wide-ranging reviews of the biology, ecology and fungal associates of orchids (e.g. Refs 19, 20, 21). Whereas most orchids investigated have an association with fungi, only some studies demonstrate ecological specificity or the ecological reliance of the orchid for a fungal associate. The nature of this association, although historically considered mutualistic, has more recently been recognised
Conservation genetics
The past two decades have seen an increase in the use of molecular techniques in the field of orchid conservation, from protein studies (mostly alloenzymes) to DNA-based methods [amplified fragment length polymorphisms (AFLPs), microsatellites and DNA sequencing] [37]. Research groups in botanic gardens worldwide, often in collaboration with universities, have had a seminal role in the development of molecular approaches, with the Jodrell Laboratory at the RBG Kew representing a standout
Propagation
Outside of the large amateur interest in the propagation and culture of orchids, botanic gardens remain the major institutional organizations involved in orchid horticulture. The integration of scientific disciplines with practical horticulture found in many botanic gardens provides an ideal platform for combining knowledge acquisition with horticultural practice and presents exciting opportunities for botanic gardens to have a major role in translocation programs [7].
Unlike their epiphytic
Seed bank development
One characteristic of orchids that provides outstanding opportunities for conservation is their dust-like seed. A single seed capsule is capable of producing tens of thousands to millions of seeds [57], providing a ready and effective way to seed bank a species with as little as one seed capsule.
Despite the popularity of orchids, seed banking is in its infancy, with few empirical studies and a lack of general guiding principles, unlike the sophisticated approaches developed for seed banking of
Conservation priorities and education
Without doubt, the financial and time resources available to conserve biodiversity adequately are insufficient. Priority setting for conservation is usually focused on the conservation status of a species, or based on its evolutionary and taxonomic significance, with programs implemented often without analysis of the cost of management and likelihood of success [64]. Orchid conservation programs are no exception and often it is the most charismatic (e.g. the lady's slipper orchid project) or
Conclusion
The complexities of an orchid conservation program represent significant infrastructure and intellectual investment. Although relatively straightforward for epiphytic species, conservation of the one third of species that are terrestrial can represent significant technological challenges, as we move from species with low levels of biotic specialization and specificity to species with intricate and obligate ecological requirements. For some areas of specialization, such as mycorrhizal
Acknowledgements
The authors acknowledge the many colleagues and partner institutions who share our passion for conservation of orchids and who continue to marvel at these most beguiling of plants.
Glossary
- Achlorophyllous
- plants without chlorophyll.
- Adaptive radiation
- process in which one species gives rise to multiple species that exploit different niches.
- Axenic culture
- the culture of an organism that is entirely free from other contaminating organisms.
- Epiphyte
- a plant growing on another plant for mechanical support, although not parasitic, deriving its moisture and nutrients from the rain and air.
- Genetic bottleneck
- occurs when a portion of a population is either killed or prevented from reproducing
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Cited by (98)
Identifying gaps in the ex situ conservation of native plant diversity in China
2023, Biological ConservationTerrestrial and epiphytic orchids exhibit different diversity and distribution patterns along an elevation gradient of Mt. Victoria, Myanmar
2023, Global Ecology and ConservationAssessing conservation efforts against threats to wild orchids in China
2020, Biological ConservationCitation Excerpt :Botanical institutes with orchid ex situ collections are expected to play leading or assisting roles in conservation translocations - more so than for most other groups of plants - because of the dependency of orchid seeds on mycorrhizal fungi for germination (Swarts and Dixon, 2009b). Overcoming this dependency requires specific technical knowledge when establishing ex situ collections and carrying out reintroductions (Swarts and Dixon, 2009b). China is among the world's plant diversity centers with >31,000 (~10%) of the world's known vascular plant species native to the country (Wu et al., 2013; Wang et al., 2015; Qin et al., 2017a; Ren et al., 2019).
A comprehensive review on threats and conservation status of orchids
2024, Journal of Applied Biology and Biotechnology