General recommendations for conservation of relict trees via living ex situ collections
To secure the survival of threatened relict trees in the long run, international coordination between botanic gardens and arboreta needs to be significantly improved. Additionally, maintaining of living ex situ collections should ideally be part of an overall conservation strategy including other actors (local administration, national parks, foresters, etc.) as well as other ex situ and in situ approaches, which can be exemplified by successful conservation of Abies nebrodensis (Raimondo and Schicchi 2005; Saporito et al. 2009). Such integrated conservation actions, therefore, should be always chosen for relict trees with extremely low number of remaining individuals or for species not reproducing sexually, which is clearly the case for Z. sicula.
Thus, a number of scientific questions remain to be answered, particularly how to establish and maintain living ex situ collections that represent the entire range of the taxa’s genetic diversity including the scientific documentation of the provenance data. The following general conclusions and recommendations are drawn from our survey concerning the conservation of the relict trees by means of living ex situ collections:
| 1. |
Establishment of a global priority list of the most important relict trees including their global conservation status. |
| 2. |
Botanic gardens and arboreta in regions and countries with emblematic relict trees should integrate the ex situ conservation of these taxa into their conservation strategies and action plans. |
| 3. |
For relict genera with several species, conservation priority should be given to the most threatened taxa and/or to narrow endemics. |
| 4. |
Botanic gardens and arboreta should ensure that their ex situ collections and associated data (e.g. list of relict trees in cultivation, their origin and collection size) are accessible to the scientific and conservation community. |
| 5. |
Botanic gardens and arboreta should develop public awareness and outreach programmes in regions where relict tree species are most at threat. As with all successful conservation activities, the involvement of local communities and organisations is critical to the long term conservation of threatened species, and should be encouraged and supported from the earliest stages of conservation planning. |
| 6. |
For newly created ex situ collections only well-documented plant material with detailed information on its origin should be used, while for existing, often very old collections, a thorough investigation of the provenance data for all relict trees in cultivation should be undertaken. |
| 7. |
Large scale genetic studies should be undertaken, ideally at genus level, in order to verify and/or clarify provenance of ex situ collections of threatened relict trees in cultivation. |
| 8. |
Further research concerning the minimum number of cultivated trees per botanic garden and taxon in order to assure the conservation of a maximum of the genetic diversity for a given taxon should be carried out. |
| 9. |
For the most threatened relict tree species and/or genera, well-coordinated specialist groups should be created in order to act globally and to develop a long term ex situ conservation strategy for these taxa. These specialist groups should define, among others, the geographical distribution of ex situ collections and assure the genetic and biogeographical representativeness of used plant material. |
| 10. |
Botanic Gardens Conservation International ( http://www.bgci.org) and the Global Tree Specialist Group of the Species Survival Commissions of IUCN ( http://www.globaltrees.org) are ideally placed to coordinate the development of comprehensive global ex situ conservation research and action for threatened relict trees through its numerous botanic garden members and affiliated partners. |
