Tropical forest ecosystems: The pinnacle of life on Earth
12 October 2015 (4055 visits)Tropical rainforests are among the most outstanding natural ecosystems on the planet, representing the pinnacle of life on Earth. Vegetative production (2 kilos per square meter each year) is more than double that found in the most productive temperate forests, while species diversity is enormous and as a whole the tropical forest system has been identified as the most important natural regulator of the Earth's climate.
Tropical rainforests, among which the Amazon is the largest single tract on Earth, ring the entire globe between the tropics, where rainfall exceeds an average of 1500 mm per year (6 feet) and where temperatures do not fall below an average of 17ºC throughout the year.
Rainforests are an entirely self-sufficient ecosystem, requiring only the steady input of sunlight to maintain plants, which in turn maintain fauna through complex webs of interactions, checks and balances.
Plants form the basic structure of the forest upon which everything else depends. Vegetation is broadly arranged into strata. The most readily observable division is between the canopy –a stratum exposed to the full effects of sun and wind- and the undergrowth, which is relatively poorly lit. The contrast between these microclimates can be striking and goes some way towards explaining the complexity of life forms adapted to a unique array of microclimates and the micro ecosystems they contain.
Animal life is adapted to the forest's complex structure. In the different strata the availability of food, opportunities for concealment and possible modes of locomotion vary greatly. Animals living in the treetops can readily obtain large quantities of vegetative foods (flowers, leaves, fruit, etc.) but must have limbs adapted to climbing, swinging, jumping, gliding or flying from tree to tree. In contrast, ground dwellers have little or no climbing ability and depend largely on food falling down from above.
Only recently has the treetop community of plants and animals become a focus of interest to biologists, and the canopy is being revealed as exceedingly rich in life forms. More than half of all the forest's animals are now believed to be arboreal (tree-dwelling), with the majority of these species completing their entire lifecycles without ever descending to ground level.
