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“Arctic-boreal” includes arctic and boreal species (USDA hardiness zones 1–3), “temperate” includes warm and cold temperate species (USDA hardiness zones 4–8), “tropical” includes tropical lowlands (USDA zones 10–11, below 1500m elevation), tropical highlands (USDA zones 10–11, above 1500m elevation), and subtropics (USDA zone 9).
