title: Irregular droughts trigger mass flowering in aseasonal tropical forests in asia.
abstract: General flowering is a community-wide masting phenomenon, which is thus far documented only in aseasonal tropical forests in Asia. Although the canopy and emergent layers of forests in this region are dominated by species of a single family, Dipterocarpaceae, general flowering involves various plant groups. Studying proximate factors and estimating the flowering patterns of the past and future may aid our understanding of the ecological significance and evolutionary factors behind this phenomenon. Here we show that this phenomenon is most likely triggered by irregular droughts based on 10 years of observations. In the aseasonal forests of SE Asia, droughts tend to occur during transition periods from La Niña to El Niño, which results in an irregular 6-7-yr cycle involving a dry period with several droughts and a wet period without droughts. The magnitude of a flowering event also depends on the timing of droughts associated with the El Niño southern oscillation (ENSO) cycle, with the largest events occurring after an interval of several years with no flowering. Because most plant species can only reproduce successfully during large flowering events, changes in the ENSO cycle resulting from global warming, may have serious ramifications for forest regeneration in this region.
authors.affiliation: Center for Ecological Research, Kyoto University, Otsu 520-2113, Japan;
authors.forename: Shoko
authors.initials: S
authors.lastname: Sakai
authors.forename: Rhett D
authors.initials: RD
authors.lastname: Harrison
authors.forename: Kuniyasu
authors.initials: K
authors.lastname: Momose
authors.forename: Koichiro
authors.initials: K
authors.lastname: Kuraji
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Nagamasu
authors.forename: Tetsuzo
authors.initials: T
authors.lastname: Yasunari
authors.forename: Lucy
authors.initials: L
authors.lastname: Chong
authors.forename: Tohru
authors.initials: T
authors.lastname: Nakashizuka