although the timing and length of flowering and fruit-
ing of a species vary from year to year (as do weather
patterns). The altered climate of El Nino years can in-
terrupt or shift normal phenological patterns in some
species. Individual species flower on different sched-
ules, responding independently to a variety of environ-
mental cues to initiate flowering, so flowering and fruit-
ing can be observed in at least 10% of the species
during any month of the year. Blooming patterns can
point to ecological relationships with pollinators. For
example, species that produce a few flowers per day
over a period of several months (extended flowering
or the "trapline" strategy) may favor specialized polli-
nators such as hummingbirds, hawkmoths, or bats, in
contrast to mass flowering species, which bloom for
only a week or two (the "big bang" strategy) and often
attract large numbers of small unspecialized insects.
The timing of fruit production may also be linked with
the availability of appropriate seed dispersers (see
Chap. 8, Plant-Animal Interactions).
3.2.2. Flowering
Trees. In Monteverde, most phenological observa-
tions have been carried out on the upper Pacific slope
in the area between the cliff edge and the Continen-
tal Divide. In this area, the vast majority of trees flower
once per year and the blooming period occurs at about
the same time each year (W. Haber, G. Frankie, C.
Guindon, and H. Baker, unpubl. data). However, in
figs (Ficus spp.), individuals often flower out of syn-
chrony with each other and a single tree may flower
up to three times per year (Bronstein 1988a, b). The
weather at Monteverde varies substantially from year
to year (see Chap. 2, Physical Environment), and the
flowering phenology of most trees responds to this
variation. For example, during the abnormally dry
conditions of El Nino years, some species flowered 6
months out of the normal sequence, some flowered
twice, and others did not flower at all (W. Haber, pers.
obs.). In general, tree species flower at widely differ-
ent times, so that a minimum of about 60 species of
trees are flowering at once in any given month. Dur-
ing months of peak flowering (e.g., March-May), more
than 100 species can flower simultaneously. Mini-
mum flowering activity occurs during September-
October (the months of heaviest rainfall) and November-
December (the windy-misty season).
The apparent avoidance of flowering during the
windy-misty season may be due to the difficulty of
pollination under these conditions. Flowers become
soaked with rain, pollen gets wet, nectar is diluted, and
the cold and wind discourage the activity of pollinat-
ing insects. Hummingbirds are less deterred by cold
rainy weather than insects, but few trees have hum-
mingbird-pollinated flowers. Hummingbird-pollinated
plants display a small flowering peak during October-
November, the wettest period of the year (Linhart
et al. 1987).Understory plants. Flowering of shrubs and treelets
in the understory follows the pattern seen in trees, an
increase in flowering in late dry season through the
early wet season with a peak in May-June (Koptur
et al. 1988). Most species show a pattern of extended
flowering, with only 15% exhibiting the mass flow-
ering pattern that is common among trees.3.2.3. Fruiting
Trees. Fruit production is highest from September
through January and lowest from June to August.
However, 30—40 species of trees can be found in fruit
in any month of the year on the upper Pacific slope.
Some tree species (e.g., Matayba sp., Sapindaceae,
Beilschmiedia spp., Lauraceae) fruit heavily only at
2-year intervals and produce few or no fruits in al-
ternate years (Wheelwright 1986; W. Haber, pers.
obs.). The timing of fruit maturation can shift substan-
tially within certain species depending on weather
conditions.Understory shrubs and treelets. Although the fruiting
of understory shrubs is less seasonal than their flow-
ering and much less concentrated than in trees, most
species produce fruit during late wet season and early
dry season, as do trees (Koptur et al. 1988).3.2.4. Leaf Flushing
Trees. A peak in new leaf production in trees occurs
during the late dry season (February-April), whereas
minimum leaf flushing occurs from August through
December, the wettest period of the year. Two major
patterns of leaf flushing have been observed at Monte-
verde: (1) all old leaves drop and are quickly replaced
by an entire crown of new leaves, and (2) old leaves
are maintained with inconspicuous loss of individual
leaves, while the primary addition of new leaves oc-
curs during twig growth, often in April—May, preced-
ing the wet season. The flowering of mass-blooming
species is frequently associated with the period of new
twig growth and leaf flushing in both patterns (e.g.,
Ilex spp., Lonchocarpus spp., Ocotea spp., Xylosma
spp.). A few species of Monteverde trees are decidu-
ous (e.g., Cedrela tonduzii, Erythrina lanceolata,
Meliosma vernicosa, Ormosia cruenta, Per sea ameri-
cana, Sapium glandulosum, Styphnolobium monte-
viridis, Pouteria fossicola), dropping all their leaves
at once and remaining leafless for a period. In Monte-65 Plants and Vegetation