Dataset for: Variations in the reproductive cycle of Bornean montane tree species along elevational gradients on ultrabasic and non-ultrabasic soils

Although lowland tree species in the ever-wet regions of Southeast Asia
are characterised by the supra-annual cycle of reproduction, the
reproductive phenology of montane tree species remains poorly understood.
In this study, we investigated the reproductive phenology of montane tree
species using litter samples that were collected every two weeks from six
rainforest sites, consisting of three elevations (1700, 2700, and 3100 m),
on Mount Kinabalu, Borneo. At each elevation, one site was on infertile
ultrabasic soil and one was on relatively fertile non-ultrabasic soil. We
used a composite sample from 10 or 20 litter traps per site and sorted it
by species. Therefore, the obtained data captured reproductive phenology
in the population of each species rather than in an individual tree.
Ten-year time series of flower and fruit litterfall were obtained for 30
and 39 tree species, respectively. Fourier analysis was used to identify
the dominant cycle of each time series. The most abundant cycle across
species was supra-annual, followed by sub-annual, and annual cycles. Many
species at higher elevations showed supra-annual cycles of flower
litterfall, whereas species in the 1700 m sites often showed annual or
sub-annual cycles regardless of soil type. No systematic differences were
found among sites for fruit litterfall. Mechanisms underlying these
elevational patterns in the reproductive cycle remain unclear but may
include more severe El Niño droughts, lower primary productivity, lower
soil fertility, and the absence of some sub-annually or annually
reproducing families at higher elevations.