Tropical Rainforests: The Brazilian Amazon

 

Layer upon layer,

     reaching to the sky.

Home of millions,

Many to perish

     at the hand of the one.

 

         Virgin tropical rainforests have been yielding to the devastating actions of the ever-growing population of one species, Homo sapiens. About half of the world's animal and plant species live in tropical rainforests, and half of these live ONLY there. This means that loss of our rainforests will be accompanied by the simultaneous loss of at least one-quarter of all multicellular organisms on Earth. The destruction of our rainforests is in considerable measure responsible for the constantly increasing rate of species extinction worldwide. This rate is estimated to be about 50,000 species per year, a rate that is about 10⁵-fold greater than the background extinction rate in the absence of human activities.

          At what rate are we destroying the Earth's tropical rainforests? Conservative estimates suggest that this rate is about 30 acres per minute, or one football field every second. This amounts to about 50,000 acres per day or 2.5% of remaining rainforests every year. At that rate, we can expect tropical rainforests to be gone in a mere 40 years. It is upsetting to realize that purely as a result of human activities, one-quarter of all animal and plant species on Earth will be gone in 40 years.

         Tropical rainforests are found near the equator. Of these, 57% are found in Latin America, with about 40% present in the Brazilian Amazon. Remaining tropical rainforests are located in Southeast Asia and the Pacific Islands (25%) as well as West Africa (18%).

         Tropical rainforests contain an incredible diversity of life. The intense vegetation that comprises the lush tapestry of interdependent creatures can be found in four layers. The Emergent Layer includes the giant trees that thrust above the dense canopy layer. These trees receive the most sunlight and consequently fix CO₂ into solid matter at rapid rates. They are adapted to high temperatures, variable humidity and high winds.

          Below the Emergent Layer, the Canopy Layer is roughly 60-90 feet above the ground. Broad irregular crowns of trees can be found covered with epiphytes and tied together with vines. This layer provides homes for a majority of the larger organisms found in the rainforests.

         The top two layers are so thick that the Understory receives only 5-15% of the sunlight; it's therefore an usually dark place. Only along rivers and roads, or in areas where man has cut away the upper layers, is sunlight sufficient to allow the undergrowth to become thick and impenetrable.

         Finally, the forest floor receives only 2% of the sunlight, and consequently few kinds of plants can survive there. The floor is covered with decomposing leaves, fruits and branches. This decaying organic layer provides much of the nutrients for the upper three layers.

         As noted above, the largest of the Earth's tropical rainforests are found in the Brazilian Amazon. This area plays vital roles in maintaining biodiversity, but it also serves as a terrestrial carbon storage site, sequestering CO₂. Moreover, it strongly influences the local climate. Unfortunately, it is the site of the world's highest rate of forest destruction; about 4 million acres are destroyed per year.

         There are several causes of this rapid rate of deforestation, but all of them are man-related. First, non-indigenous populations in the Amazon have increased tenfold since the 1960s, mostly due to immigration, from about 2 million to 20 million people. Second, industrial logging and mining are growing as a result of expanding road networks that allow access to the heart of the forests. Third, deforestation due to infiltration by colonists and ranchers has changed spatial patterns of forest loss. Again, the new highways allow penetration deep into the central basin. Finally, human-ignited wildfires, particularly in logged or fragmented areas, complete the destruction, rendering rapid restoration of native conditions impossible.

         Many international initiatives have attempted to promote conservation or at least encourage sustainable development. The largest of these, the Pilot Program to Conserve the Brazilian Rainforest, channels nearly $400 million, most coming from Europe, Japan, the U.S. and Canada. However, these efforts pale in comparison to development activities promoted by the Brazilian government. Dozens of major infrastructure projects - intended to accelerate economic development - amount to investments totaling about $40 billion over an 8-year period. These allow for construction of new highways, railroads, gas lines and hydroelectric plants. Unfortunately, key environmental agencies such as the Brazilian Ministry of the Environment have been largely excluded from planning developments.

         The impact of these massive developmental projects has been assessed to predict the pattern and pace of forest degradation over the next 20 years. The results show that the Brazilian Amazon will be drastically altered, particularly along the Southern and Eastern areas of the basin, but also in the Central and Northern parts. By 2020, few pristine regions will survive outside of the Western quarter.

         What are the actual numerical rates of Amazon deforestation? These numbers are astounding! Between 500,000 and one million acres are completely lost every year, and the rate of conversion from pristine or lightly degraded forest to moderately or heavily degraded land is 3 to 5 million acres per year.

         A primary problem with the Brazilian government's developmental plan is that no attempt has been made to evaluate the environmental costs and risks. Moreover, once started, development, including colonization, logging, mining, and land speculation, is irreversible and uncontrollable.

         Just what does this mean in terms of global environmental impact? The destruction of each acre causes the release of about 100 metric tons of CO₂. Moreover, deforestation promotes flooding, soil loss, and climate instability, all of which are detrimental to a colonizing population. Other problems include loss of the indigenous Indian populations and consequent loss of ecotourism.

         The Brazilian Ministry of Foreign Affairs currently opposes allowing international carbon-offset funds to promote forest preservation - a stance opposed by the Ministry of the Environment. The current slash-and-burn farming projects, although most devastating, are favored for their short-term benefits. There seems little hope for long-term planning when short-term profits are to be had. There are viable alternatives, including sustainable development, but it is unlikely that these will be taken. At stake is the fate of the greatest tropical rainforest on Earth, and with it, up to half of the living species found on this planet.

 

 

 

Website: http://www.rain-tree.com/facts.htm

 

Laurance, W.F., Cochrane, M.A., Bergen, S., Fearnside, P.M., Delamonica, P., Barber, C., D'Angelo, S., and Fernandes, T. (2001). The future of the Brazilian Amazon. Science 291, 438-439.