 The Five Tiny Kingdoms
Scientists
tell us that many tropical species remain to be discovered.
Did you know that some of these may be right in front of you, brushing
your
face as you thrust your way through the forest? The phyllosphere, the
world
on a leaf, can be home to many different forms of life, including
species
from the Plant Kingdom (the leaf itself), the Animal Kingdom (tiny
insects),
the Fungus Kingdom, the Algae Kingdom and the Bacteria Kingdom.
(These
are the five Kingdoms of Life.) There is even a special name for plants
that
live on other plants: epiphylls.
Mosses
and
Liverworts
The
family of mosses and liverworts, or bryophytes, seem to thrive on
certain types of leaves in the cloud forest. These epiphylls need
humidity and tend to colonize longer-living leaves with smooth
surfaces, which promote the
establishment of reproductive devices with adherent cells. An
example
of a leaf-loving liverwort is the one on the left. Some
liverworts
penetrate the leaf and may absorb water during the dry season, and many
absorb
minerals from their hosts.
Lichens
Like
Leaves
Lichens
consist of a fungus bound to a an algae or to cyanobacteria; thus they
bring together three of the Kingdoms. Costa Rica is the country with
the highest number of leaf-inhabiting (foliicolous) species of lichens,
with about 350 of the 550 species known worldwide. Indeed many species
of
lichen and other epiphylls can be found on a single leaf.
Do
Leaves
Like Lichens?
While
some epiphylls are semi-parasitic, their colonization may also benefit
the host plant, because lichens and liverworts provide a suitable
environment for nitrogen-fixing bacteria and cyanobacteria — the
forest’s fertilizers. They may also protect the leaves against
herbivores.
 Animal Life on a Leaf
Snails,
moth larvae, barklice, and worms are among the denizens of the
miniature zoo that thrives on (or under) the forest leaves. Minute
snails
and psocids (barklice) are some examples of invertebrates which feed on
foliicolous lichens and bryophytes. The damage caused by these animals
can
positively influence the diversity of life on individual leaves.
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