What is the relevance of smallholders' agroforestry systems for conserving tropical tree species and genetic diversity in circa situm, in situ and ex situ settings? A review Ian K. DawsonManuel R. GuariguataJudy LooJohn C. Weber • Ard LengkeekDavid BushJonathan CorneliusLuigi Guarino • Roeland KindtCalleb OrwaJoanne RussellRamni Jamnadass

Smallholders' agroforests may be valuable for conserving tropical trees through three main mechanisms. First, trees planted and/or retained by farmers in agri- cultural landscapes where wild stands were once found may be circa situm reservoirs of biodiversity. Second, farmland trees may support conservation in situ by providing an alternative source of product to reduce extraction from forest, and by acting as 'corridors' or 'stepping stones' that connect fragmented wild stands. Third, the additional value that