Data from: Species-specific flowering cues among general flowering Shorea species at the Pasoh Research Forest, Malaysia

1.In a unique phenomenon restricted to the ever wet forests of Southeast
Asia, hundreds of species from dozens of plant families reproduce
synchronously at irregular, multi-year intervals. The proximate
environmental cues that synchronize these general flowering events have
not been evaluated systematically because there have been no long-term,
high temporal-resolution, species-level records from the region. 2.We
present 13 years of weekly flowering records for five Shorea species as
well as daily temperature and rainfall records from the Pasoh Forest
Reserve, Peninsular Malaysia. We constructed models to evaluate
hypothesized relationships between flowering and cool temperature,
drought, and additive and synergistic effects of cool temperature and
drought for each species. Model parameters include periods of time for
floral cue accumulation and flower development and temperature and/or
rainfall thresholds required for floral initiation. Parameters estimated
using flowering observations from 2001–2011 were used to forecast
flowering for 2011–2014. 3.We show that drought and cool temperatures
acting synergistically best explain the timing of flowering events for all
Shorea species in the section Mutica and forecast the largest general
flowering event accurately. Periods estimated for signal accumulation
ranged from 54 to 90 days among species. Periods estimated for flowers to
develop ranged between 43 to 96 days and closely followed the
interspecific sequence of flowering in the Shorea species. Drought and
temperature thresholds also varied among species, with S. maxwelliana
requiring the most severe drought and S. leprosula the lowest
temperatures. 4.Synthesis. Our results indicate that cool temperatures and
low rainfall occurring on seasonal time scales of about two to three
months rather than brief cold snaps or brief droughts best explain general
flowering in Shorea species at the Pasoh Forest Reserve. Low rainfall is
equally likely in winter (December–February) and summer (July–August) and
cool temperatures are most likely in winter at Pasoh, which explains why
general flowering events are restricted to spring and fall, with more
frequent and stronger flowering in spring. In addition, species-specific
sensitivity to environmental cues suggests that future climate change will
have differential impacts on the frequency of reproduction, with potential
consequences for regeneration of these dominant species of lowland
tropical forests.