Rainforest Information, and Description
Text and photographs by David Ross

Tropical rainforests contain 1/2 of all of the worlds species. They are a biological treasure, a source medicines and foods of today and untold potential for future generations. Rainforest are an engine of oxygen production, and a regulating system for weather processes on a global scale. This forest biome, despite the continued and heroic efforts to protect it, is still under attack, and is declining at an alarming rate.

Tropical, merely means lying in the latitudes between the Tropic of Cancer (north of the Equator) to the Tropic of Capricorn (south of the equator). It is however the tropical climate, of regular warm temperatures, and an average annual rainfall of at least 100 inches, that results in conditions favoring the development of tropical rainforest.

Forest of course conjures the image of trees. Trees growing for upwards of hundreds of years if left untouched by natural disaster, or the steel of axe or chainsaw's tooth. Such forest grow under relatively stable conditions of warm temperatures and high humidity. The dense canopy (the roof containing the majority of biomass, branch-leaf, bugs and bigger critters) acts as an insulating layer, further regulating (keeping constant) the temperature and humidity within and through the layers below. Ecologist have long described forest as having strata or layers. The uppermost zone of taller canopy forming trees, is the canopy, below this slightly shorter trees may form a zone or sub canopy, below this, an area where trees and taller shrubs grow in the shade of the larger trees is a zone called the understory. Below all of these strata or layers of vegetation, is the herbaceous layer, which is comprised of plants growing close to the forest floor, the dirt or soil.

Plants do not obey boundaries drawn on biologists' diagrams. The zones described are descriptive, applicable in general terms or on average. There are canopy trees tall enough to stand apart and above their would-be canopy competitors. These are trees that break through the roof. These are the canopy emergents. A troop of howler monkeys will often roost in such a tree at night for safety. In the predawn the males will roar in chorus across from such a perch, and their thundering voice will spread outward into the forest, to announce their presence to others as far as a kilometer away.

The battle for sunlight on leaves, has resulted in a variety of strategies beyond typical roots, trunk and "limbing" ones leaves towards light. The health and wealth of a forest, it's level of pristine-ness (being left untouched for centuries) might be measured by the number and size of climbing vines, or lianas. For every rainforest movie clip in which the explorer slashes a machete through a thick vine for a drink, or to penetrate "the jungle", there is a plant that had eked out it's existence by spiraling and climbing through the branches over the decades, that has been killed or severely damaged. Lianas may start there piggybacking path to light, from a ground planted seed along a clearing, along the riverbank or a tree fall gap, or from the canopy itself.

Many of the thousands of plant species found in this biome, count on birds to disperse and ultimately plant their seeds. The seeds are wrapped in an attractive edible fruit, colorful berries signal birds and other vertebrates that there is food to be had. The birds eat the berries, and deposit the seeds in their droppings. Several species of plants get their head start by being deposited in the canopy. They start to grow from the the top, getting enough light, moisture and some nutrients from organic material in the canopy, to send thin strands towards the forest floor.

There are other plants that do not bother with seeking water and nutrients from the soil below. These plants derive their water from the rain and moisture from the air and the canopy itself. They obtain nutrients by collecting detritus (dead plant bits) from the plants above them, and creatures that live about them. Many vines, bromeliads, ferns, orchids, lichens, mosses and even certain cacti are referred to as air plants. Air plants or epiphytes, contribute to the biomass in the canopy, and to the unparallel biodiversity of rainforest.

The above descriptions may give a glimpse at the structure of the plant community of this species rich, and amazingly diverse environment. But myths prevail. One such myth is that of the impenetrable jungle, the dense wall of vegetation that requires a sharp machete and strong arm to traverse. There are areas where forest presents itself as a wall of green. These areas are usually at the forest edge. It is the common view from the river edge, or camp clearing. Where a rainforest giant has fallen, where a large canopy tree has succumb to age or wind, a large gap in the canopy can be created. Such a tree fall gap will often be choked with vines and a tangle of brush, and competing seedlings and saplings racing to fill the void, and drink in a quantity of light that forest floor may not have seen for hundreds of years--here a machete might be useful, if one had not the ability to simply go around it!