Since 2014, the International Conifer Conservation Programme (ICCP) has been planting conifer conservation hedges. This initiative is being driven by the potential for relatively large numbers of genotypes from a single threatened species being stored in a linear space. For example, save for some species of the Pinaceae and Araucariaceae, most of the 29 Critically Endangered conifer species could be effectively cultivated in hedges. See Gardner et al. (2018) Conservation Hedges - Modern-day Arks. Sibbaldia 17:1.30
The Value of Conservation Hedges
If botanic gardens are going to have any valid claim to use their collections as a conservation genetic resource, then they need to be more than stamp collections of single individuals. Certainly, in the climate of reduced fieldwork funding and the stifling effect of the Nagoya Protocol for transferring material, every opportunity needs to be taken with all available space being fully utilised to accommodate ‘hard-won‘, naturally sourced plant material. After all, this is what underpins the vital research of botanic gardens and supports the wider, equally important remit of conserving plant biodiversity in the face of global environmental change and mass extinctions. Conservation hedges provide an ideal opportunity for maximising the number of genotypes in a linear space, hence helping to preserve the evolutionary potential of the species.
The RBG Edinburgh Yew Conservation Hedge
In 2014 work commenced on replacing the RBG Edinburgh Garden’s perimeter hedge of IIex aquifolium which had little or no scientific value, with almost 2,000 trees of Taxus baccata with research and conservation benefits. The hedge comprises two categories of plants: about 30 per cent are from cuttings from iconic heritage yew trees throughout the UK and Ireland, and about 70 per cent are from seed collections made from native trees from across the natural distribution of Taxus baccata. Each plant in the hedge is labelled with a unique accession number and qualifier and is digitally mapped.
1. Dundonnel House 2. Great Fraser 3. Crathes Castle 4. Fortingall 5. Dunkeld Cathedral 6. Robert The Bruce 7. Broich House 8. Whittingehame 9. Finlaystone House 10. Colinton Church Manse 11. Ormiston Hall 12. Malleny Garden 13. Craigends House 14. Kelburn Castle 15. Loudon Castle 16. Traquair House 17. Dryburgh Abbey 18. Martindale 19.Borrowdale 20. Muncaster Castle 21. Florence Court 22. Crom Castle 23. Taxal 24. Llangernyw 25. Nantglyn 26. Buttington 27. Muckross Abbey 29. 28. Much Marcle 29. Stow-on-the-Wold 30. Bampton 31. Ankerwycke 32. Down House. 33. Crowhurst 34. Selborne 35. Twyford 36. Ashbrittle
Since the establishment of the yew conservation hedges further opportunities have arisen to plant more conservation hedges at RBGE and other gardens which form part of the network of ‘safe sites’ for the ICCP. Four hedges are at have been planted using the threatened Chilean endemic Prumnopitys andina (the Chilean plum yew).
In 2016, 151 plants of Saxegothaea conspicua were planted in a hedge that surrounds the newly re-built Botanics Cottage. To our knowledge, this is the first time that Saxegothaea conspicua has been used as a hedging plant. The hedge comprises 59 genotypes from five accessions collected from Reserva Biológica Huilo Huilo in Chile’s Los Ríos Region.