Leaf flushing during the dry season: The paradox of Asian monsoon forests

Abstract

Aim: Most deciduous species of dry monsoon forests in Thailand and India form new leaves 1-2 months before the first monsoon rains, during the hottest and driest part of the year around the spring equinox. Here we identify the proximate causes of this characteristic and counterintuitive 'spring-flushing' of monsoon forest trees. Location: Trees of 20 species were observed in semi-deciduous dry monsoon forests of northern Thailand with a 5-6-month-long severe dry season and annual rainfall of 800-1500 mm. They were growing on dry ridges (dipterocarp-oak forest) or in moist gullies (mixed deciduous-evergreen forest) at 680-750 m altitude near Chiang Mai and in a dry lowland stand of Shorea sia..