The main tree commodity crops have all been subject to formal breeding, although the efforts involved have often been ad hoc based on the availability of germplasm to the breeders involved (Mohan Jain and Priyadarshan, 2009). Partly, ad hoc approaches reflect the fact that the main centres of production of tree commodities are spread across the tropics and are often outside their native ranges (see Fig. 1 for the five examples discussed in Section 4.1; UNCTAD, 2011). As such, tree commodities provide an excellent example of how the international transfer of plant genetic resources (both for breeding purposes and simply for planting by farmers) has been and will continue to be important for supporting smallholders’ livelihoods (the importance of international tree germplasm exchange is more widely discussed by Koskela et al.,
2014, this special issue).