8. Ex situ conservation and integration with in situ methods
In the seventh and final review of this special issue, Pritchard et al. (2014) discuss ex situ conservation measures for trees, their integration with in situ approaches, and the particular roles of botanic gardens in conservation. Botanic gardens have participated widely in the collection and storage of tree seed, pollen and herbar- ium specimens, and in the establishment of living collections in vitro and in arboreta (BGCI, 2014; MSB, 2014). They have, how- ever, moved far beyond their traditional role in ex situ conservation and have been widely involved in forest inventory, biological char- acterisation and threat mapping initiatives that support in situ con- servation, as well as in the design of in situ reserves. From an ex situ collection perspective, of concern is the limited representativeness in collections of total intraspecific variation, as botanic gardens have traditionally been more interested in ‘capturing’ species than the genetic variation within them (Kozlowski et al., 2012; Oldfield, 2009). Difficulties in the regeneration of stored tree seed – such as the long period to maturity after planting, large growth form and the outbreeding reproductive system of most species – are also of concern, once seed viability under storage has decayed to the level at which regeneration is required (Dawson et al., 2013). Sig- nificant efforts are therefore being made to minimise the need for regeneration by ensuring optimal seed processing before stor- age and the maintenance of seed in the best possible storage conditions.