Abstract:
Abstract Flowering and fruiting as phenological events of
12 tree species in an evergreen tropical mountain rain forest
in southern Ecuador were examined over a period of 3–
4 years. Leaf shedding of two species was observed for
12 months. Parallel to the phenological recordings,
meteorological parameters were monitored in detail and
related to the flowering and fruiting activity of the trees. In
spite of the perhumid climate of that area, a high degree of
intra- and inter-specific synchronisation of phenological
traits was apparent. With the exception of one species that
flowered more or less continuously, two groups of trees
could be observed, one of which flowered during the less
humid months (September to October) while the second
group started to initiate flowers towards the end of that
phase and flowered during the heavy rains (April to July).
As reflected by correlation coefficients, the all-time series
of meteorological parameters showed a distinct seasonality
of 8–12 months, apparently following the quasi-periodic
oscillation of precipitation and related cloudiness. As
revealed by power spectrum analysis and Markov
persistence, rainfall and minimum temperature appear to
be the only parameters with a periodicity free of long-term
variations. The phenological events of most of the plant
species showed a similar periodicity of 8–12 months,
which followed the annual oscillation of relatively less and
more humid periods and thus was in phase or in counterphase
with the oscillations of the meteorological parameters.
Periods of unusual cold or dryness, presumably
resulting from underlying longer-term trends or oscillations
(such as ENSO), affected the homogeneity of quasi-12-
month flowering events, fruit maturation and also the
production of germinable seeds. Some species show
underlying quasi-2-year-oscillations, for example that
synchronise with the development of air temperature;
others reveal an underlying decrease or increase in
flowering activity over the observation period, influenced
for instance by solar irradiance. As Ecuador suffers the
highest rate of deforestation in South America, there is an
urgent need for indigenous plant material for reforestation.
A detailed knowledge of the biology of reproduction in
relation to governing external factors (mainly climate) is
thus required.
