grandis germplasm in the region (e.g., Kjaer and Siegismund, 1996). Systematic R&D
on T. grandis started long after the species was introduced from Asia to other regions. According to Mathauda (1954), one of the first provenance trials for the species was established in India in 1930. It was not until the early 1970s, however, that the first series of international provenance trials was established. A total of 75 provenances, including many African and Latin American landraces, were collected between 1971 and 1973 and distributed for 48 trials established in India, Southeast Asia and West Africa, as well as in Central and South America ( Keiding et al., 1986). These provenance trials continue to provide valuable information on the performance and traits of T. grandis seed sources for plantation and improvement programmes ( Kjaer et al., 1995). Khaya senegalensis offers find more an example of the second PLX3397 supplier above-mentioned category of tropical hardwoods.
For centuries, the species was exploited for various purposes within its natural distribution range in West and Central Africa ( Karan et al., 2012), before introduction to other regions started a few decades ago. In the late 1960s, K. senegalensis germplasm from 24 seed sources, spanning 11 of the 19 African countries where the species occurs naturally, was transferred to Australia for R&D ( Nikles, 2006 and Nikles et al., 2008). Later, K. senegalensis was established in Asia and tropical America. There is continued interest especially in Australia to transfer more germplasm for further R&D ( Fremlin, 2011 and Karan et al., 2012). Other examples where tropical hardwood germplasm transfer has increased following initial R&D include Swietenia macrophylla and Cedrela odorata, the most important native hardwoods of Central America. Since 1980, the demand for seed of CYTH4 these two species and other native trees has increased considerably in Central America, after R&D efforts spearheaded by the Tropical Agricultural Research
and Higher Education Centre (CATIE) and other research institutes. This research demonstrated the potential of these species to provide high quality timber from a relatively short rotation. Today, S. macrophylla and C. odorata are also planted widely in other regions, such as Africa and Asia. There are many other emerging high-value tropical hardwoods for which R&D has been intensified recently (e.g., Nichols and Vanclay, 2012, Camcore Annual Report, 2011 and Midgley et al., 2010). These include Milicia excelsa in Africa, Pachira quinata and Terminalia amazonia in the tropical Americas, Ochroma pyramidale, Endospermum medullosum and Santalum spp. in the Pacific, and Dipterocarpus spp. in Southeast Asia. These species have often been unsustainably harvested from natural forests, but efforts are now being made to conserve their genetic resources and to develop plantation-based industries (e.g.