A major part of the botanical gardens conservation work consists of ex-situ collections. The aim of these collections is to safeguard a representative sample of the genetic diversity of each population targeted. The ex-situ collections act as insurance against the loss of populations in the wild. Before 2005 the RTBG's conservation programs largely consisted of potted collections of rare & threatened Tasmania flora. From 2006, with the advent of the Tasmanian Seed Conservation Centre the RTBG's ex-situ collections now primarily focus on the storage of seed collections.
Prior to the seedbank our ex-situ collections consisted of 128 individuals representing 20 threatened taxa curated by the gardens nursery. As of the 15th of May 2013 the seedbank holds 371 collections of 253 threatened taxa, totalling 9.5 million seeds.
The nursery now focuses it's conservation efforts on those threatened species that do not set seeds (like Lomatia tasmanica) and seed orchards of species difficult to collect directly in the field.
The Gardens maintains several species in potted ex-situ collections, for one or more of the following of reasons –
- some species do not produce viable seed,
- some species are being grown for re-introduction purposes,
- some are maintained for educational display purposes, and
- some are being grown as seed orchards for the Tasmanian Seed Conservation Centre
Of this last category, since 2007 the RTBG Nursery has grown 39 different species for seed orcharding, with 25 of the 39 being rare and threatened plants in Tasmania. Sixteen of these have been completed (ie. the seed has been successfully harvested and banked), 18 are still active and 5 are in propagation.
Some notable successes over the last six years include...
2008 Cyphanthera tasmanica (threatened & Endemic) - 16,000 seeds
2009 Phebalium daviesii (threatened & Endemic) - 34,700 seeds
2010 Boronia rhomboidea - 83,400 seeds
2011 Xerochrysum bicolor (threatened) - 455,300 seeds
2012 Australina pusilla ssp muelleri (threatened) - 527,200 seeds
2013 Mentha australis (threatened) - 29,100 seeds