First Impressions: Into the Forest
Welcome to the green and complex world of the
rain forest. As for first impressions, it doesn’t matter
whether you’re standing in Peruvian, Brazilian,
Ecuadorian, Belizean, Costa Rican, or Venezuelan
rain forest— at first glance it all looks pretty much the
same (plates 3- 1– 2). It even sounds, smells, and feels
generally the same. All over the equatorial regions of
the planet where rain forest occurs, the forest tends
to have a similar physical structure and appearance.
But this impression is deceptive. On closer inspection,
numerous differences become apparent in rain forests
both within and among various geographical areas. On
a global scale, evolution has produced very different
species, indeed different families of plants and animals
from one biogeographic region to another. One does
not find orangutans or rattan palms in Venezuela or
sloths or hummingbirds in Borneo. Leaf- cutter ants,
unmistakable and nearly ubiquitous throughout
the Neotropics, exist nowhere else. And within the
Neotropics, rain forests in Costa Rica are different in
many significant ways from their counterparts in Brazil.
And in Brazil, Amazonian forests show considerable
differences from site to site. Some sites have dense rain
forest, some more open forest with an abundance of
palms, some open forest without palms, and some
open forest with abundant lianas. Rain forests on poor
soils differ markedly from those on richer soils, just as
rain forests on terra firme (terra firme is a term used for
area of forest and savanna that occur off the riverine
floodplain) are distinct in some important ways from
those on Amazonian floodplains (várzea).
Yet the overall similarities, apparent as first
impressions, are indeed striking. Charles Darwin
(1906) wrote of his initial experience in tropical rain
forest:
When quietly walking along the shady pathways,
and admiring each successive view, I wished to find
language to express my ideas. Epithet after epithet
was found too weak to convey to those who have
not visited the intertropical regions the sensation of
delight which the mind experiences.
Imagine we are standing at the edge of a Neotropical
rain forest. It’s just after dawn; the hot sun has not yet
risen high, and the air is sufficiently humid that the
dampness makes it seem almost cool. Rain clouds are
already gathering, but it’s not yet raining. There is a
well- marked trail leading us into the forest. It rained
during the night, and the trail is muddy and slippery.
There is much to take in. It seems strangely quiet,
though a few bird and insect calls, especially those of
cicadas, periodically break the serenity. Eyeglasses fog
because the humidity is so high. The sky is pale, not
blue, and the brightness makes it difficult to discern
color on the large toucan that sits partially exposed on
a protruding bare limb high in the forest canopy. Fallen
dry leaves rustle, for some sort of animal, perhaps an
agouti or a tinamou, is moving through them. But it is
the trees, so many trees, to say nothing of the vines and
epiphytes, that first grab our attention.
How immense the forest seems, and how dark and
enclosing. Dense canopy foliage shades the forest
interior, especially in the attenuated early- morning
light. Even at midday, when the sun is high overhead,
only scattered flecks of sunlight dot the interior forest
floor. Shade prevents a dense undergrowth from
forming, and the forest floor appears fairly open, lacking
a thick shrub layer. Plants we’ve seen only as potted
houseplants grow here in the wild. There’s a clump of
Dieffenbachia directly ahead on the forest floor. Large
arum vines, philodendrons such as Monstera, with
its huge, sometimes deeply lobed leaves, are climbing
up some of the tree trunks. The biggest trees tend to
be widely spaced; many have large, flaring buttressed
roots, and some have long, extended prop roots. All
the trees are broad- leaved. Absent are the needle-
leaved trees of the temperate zone, the pines, spruces,
and hemlocks. Instead, palms abound, especially in the
understory, many with whorls of sharp spines around
their trunks. Tree boles are impressively straight,
rising to considerable height before spreading into
crowns, which are hard to clearly discern because so
much other vegetation grows among them. Clumps of
cacti, occasional orchids, many kinds of ferns, and an
abundance of pineapple- like plants called bromeliads
adorn the widely spreading branches. It’s frustrating
to try to see the delicate flowers of an orchid clump
so high above us, but binoculars help. Vines hang
seemingly haphazardly, some draping through several
nearby trees. Rounded, basketball- size termite nests
are easy to spot on the trees, and the dry tunnels made
by their colonial inhabitants vaguely suggest brown
ski trails running along the tree trunks. On the forest
floor we see trails made by the comings and goings ofChapter 3. Rain Forest: The Realm of the Plants
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