Seed storage behaviour of native forest tree species of northern Thailand

ABSTRACT: Storage of native forest tree seeds is essential for the development of seed-based forest restoration methods, such as direct or aerial seeding and for increasing representation of native trees in nurseries, for conventional tree planting. The study, presented here, investigated seed germination, dormancy and storage behaviour of 16 native tree species, used to restore upland evergreen forest in northern Thailand. Eleven of them, had orthodox seeds (storable at minus 20˚C and 5% moisture content): a proportion consistent with other studies of seasonally dry tropical forest: Acrocarpus fraxinifolius, Adenanthera microsperma, Alangium kurzii, Bauhinia variegata, Choerospondias axillaris, Gmelina arborea, Hovenia dulcis, Manglietia garrettii, Melia azedarach, Phyllanthus emblica and Prunus cerasoides. Four species had recalcitrant seeds: Artocarpus lacucha, Dimocarpus longan, Horsfieldia amygdalina and Syzygium albiflorum. All except D. longan set seed in the early rainy season and could therefore be used for direct or aerial seeding without storage. Inclusion of D. longan and Diospyros glandulosa (the latter classed as intermediate, with seeds that could be partially dried but not frozen) in forest restoration plantings will only be possible by nursery-based sapling production and conventional tree planting.