The natural distribution of P. radiata is limited to a handful of remaining

populations in Mexico and the USA where it has no role in commercial forestry ( Rogers, 2004). The species was introduced into Australia in the 1850s for ornamental plantings and R&D work started there one hundred years later, resulting in significantly improved germplasm ( Wu et al., 2007). Today, P. radiata is widely planted in diverse countries including Chile and New Zealand, in addition to Australia ( Rogers, 2004). Germplasm transfer of currently widely-used tropical and subtropical plantation trees such as Acacia, Eucalyptus Bcl-2 inhibitor and Pinus spp. started soon after their native ranges were colonised by Europeans ( Bennett, 2011). The development Erastin cost of their historical transfer patterns is similar to that of the temperate and boreal species:

large-scale tree planting efforts first created demand for germplasm transfer for production purposes and, later, germplasm was also transferred increasingly for R&D. By the 19th century, collection and export of Acacia and Eucalyptus spp. seed from Australia was well organized. During the same century, eucalypts, including E. camaldulensis, E. globulus and E. tereticornis, were widely planted throughout the temperate and Mediterranean-like climatic regions of the world ( FAO, 1979 and Freeman et al., 2007). Acacias such as A. saligna, A. cyclops and A. longifolia were similarly exported to southern Africa ( Carruthers et al., 2011). Exploration, collection and assessment of these species

and the transfer of their germplasm for production purposes were intensified in the 20th century, and more systematic R&D work was initiated around 50 years ago. Eucalyptus camaldulensis and E. globulus, for example, have been introduced from Australia to 91 and 37 countries, respectively ( Table 1). Of the more than 600 Eucalyptus species, just nine cover 90% of the planted eucalypt area globally: E. camaldulensis, E. dunnii, E. grandis, E. globulus, E. nitens, E. pellita, E. saligna, E. tereticornis and PRKACG E. urophylla ( Harwood, 2011). Of the 1,012 Australian Acacia species, it is estimated that 386 have been introduced by humans outside Australia ( Richardson et al., 2011), though R&D efforts in the last decades have largely focused on just a few tropical species, most notably A. mangium and A. crassicarpa. Today, A. mangium is estimated to be planted in 25 countries outside its native range ( Table 1). In addition to Acacia and Eucalyptus species, the germplasm of several fast-growing pines, predominantly from Central America, Mexico and the southern Unites States, has been transferred for establishing plantations throughout the tropics and subtropics. In Mexico, one of the first collections of Pinus patula seed was carried out in the early 20th century and the material was transferred to South Africa for establishing the first pine plantations in the country ( Butterfield, 1990).