"The Amazon is a library for life sciences, the world's greatest pharmaceutical laboratory and a flywheel of climate," says Thomas Lovejoy of the Smithsonian Institute. Such may be said of the Sunderbans or the hill forests of Chittagong as well. Many facts relating to our forest are unknown because of the lack of interest and research funding needed to make these discoveries. In the Brazilian part of the Amazon rain forest, one estimate by the U.S. Academy of National Sciences in 1982 states that a typical 4 square mile patch of forest may contain 750 species of trees, 125 kinds of mammals, 400 types of birds, 100 of reptiles and 60 of amphibians. Each type of tree may support more than 400 insect species. The forest region here, in our country, or in Brazil is a virtually untapped storehouse of evolutionary achievement that will prove increasingly valuable to mankind as it yields its secrets.

However, biologists who explore biodiversity see it vanishing before their eyes, amply demonstrated by the fact that they now live in a world of wounds and practice a scientific discipline with a deadline. The reason: deforestation. Further, deforestation has devastating impacts on climatic change and on natural processes upon which the Earth's delicate balance depends.

Brazil, home to about half the Amazonian basin, has shown reckless penchant for squandering resources that matter to all mankind. Says Al Gore, a conservationist and former US vice-president who visited the densely packed forest areas, "The devastation is just unbelievable. It's one of the great tragedies of all history."

How is biodiversity affected?
Damage to intact forests, specifically when they are broken up into isolated patches when partly logged or when fires are set (as has happened in Brazil and Indonesia) directly threatens biodiversity. While covering only 6% of the Earth's land surface -- about the same as the 48 contiguous United States -- the world's forests are losing an area of half the size of Florida, USA each year. With other rich environments under similar assault, including coral reefs (two-third's degraded) and salt marshes and mangrove swamps (half eliminated or radically altered), the extinction rate of species is rising everywhere.

Not all threatened species disappear immediately. Most suffer loss of their habitat ranges and gene pools to dangerously low levels, eventually descending to what biologists call the "living dead." Throughout the world 976 tree species are classified as critically endangered.

Why should we care about biodiversity?
Undeniably true, humanity's food supply comes from a narrow sliver of biodiversity. Throughout history, people have gathered or cultivated about 7000 plant species for food. Today only 20 species provide 90% of the world's food with maize, wheat and rice supplying more than half.

Natural pharmaceuticals offered by biodiversity are also underutilized. Only a few hundred wild species have served to stock our antibiotics, anticancer agents, painkillers and blood thinners. The biochemistry of the vast majority of species is an unfathomable reservoir of new and potentially more effective substances. Caught in an endless struggle for survival, these species have devised myriad ways to combat microbes and cancer-causing runaway cells. As the enhancement of agriculture and medicine become the mainstay for the survival of exploding populations in the world, there is hardly an alternative to conserving the forest.

Furthermore, the biosphere gives us renewed soils, energy, clean water, and the very air we breathe, all free of charge. The more species that compose wild communities, the more stable and resilient the planet becomes as a whole.

The forest as nutrient recycler
The forest functions like a delicately-balanced organism that recycles most of its nutrients and much of its moisture. Wisps of steam float from the top of endless palette of green as water evaporates off the upper leaves, cooling the trees as they collect the intense sunlight. Air currents over the forest gather this evaporation into clouds, which return the moisture to the system in torrential rains. Dead animals and vegetation decompose quickly, and the resulting nutrients move rapidly from the soil back to the growing plants. The forest is such an efficient recycler that virtually no decaying matter seeps into neighboring rivers.

Left to it's own devices, the rain forest or mangrove forest is an almost self-sustaining system that thrives indefinitely. But when stripped of its trees, the land becomes inhospitable. Most of the forest soil becomes nutrient-poor and ill-suited for agriculture. The rain forest or the mangrove forest has an uncanny capacity to flourish in soils that elsewhere would not even support weeds. It is worth noting that Henry Ford tried twice to carve rubber empires out of the rain forest in the 1920 and 30s.

But when the protective canopy was cut down, the rubber trees withered under the assault of sun, rain and pests. The story is the same here in our country. To encourage settlement in the Chittagong hill tracts, the government offered many incentives in the coastal region of the Sunderbans, allowing settlers to claim arable land by clearing off its trees. Unfortunately, for the settler's, their dreams of agriculture-based prosperity turned into bitter disappointment.

How do forests affect climate change?
Because of the huge volume of clouds it generates, the forest system plays a major role in the way the sun's heat is distributed around the globe. Any disturbance of this process could produce far-reaching, unpredictable effects. The Amazon alone stores about 75 billion tons of carbon in its trees, which when burned, spew carbon dioxide into the atmosphere. Since the air is already dangerously overburdened by carbon dioxide from the cars and factories of industrial nations, the torching of either the Amazon or the destruction of the Sunderbans could magnify the greenhouse effect, the trapping of heat by atmospheric carbon dioxide. Scientists fear that the globe will begin to warm up, catapulting dramatic climatic changes. This summer, most European countries and the U.S have recorded extreme temperatures (40 degrees centigrade) of which were previously unheard. This, in turn, has taken a heavy toll on human lives.

The culprits
Shrimp cultivation, logging, agriculture in forested areas, and insecticide-use are some of the major causes of forest destruction in bio-rich areas. In Bangladesh about 12,000 acres of the Chittagong coastal region that include Parabon, a man-made forest in offshore Sonadia and Ghatibhanga, have been encroached upon by ruling party men to create enclosures for shrimp cultivation. Shrimp cultivation has been known to increase water salinity, inhibiting growth of trees that depend on fresh water, such as mangroves. In the coastal waters surrounding the Sunderbans, a section of greedy fishermen use insecticides in the water area to amass bigger catches, which indirectly and adversely affects the growth of forest resources, including plants and animals. Forest areas that include innumerable channels are twice daily submerged by the polluted sea during high tide. In Peru, forests are being cleared to grow coca for cocaine production.

In Brazil, farmers and cattle ranchers engage in an annual rite of destruction: clearing land for crops and livestock by burning the rain forests of the Amazon. An estimated 12,350 square miles of Brazilian rain forest -- an area larger than Belgium -- has been reduced to ashes as a result. Similarly, in Bangladesh, the direct assault by humans on forest resources goes unabated. Landless farmers in Shyamnagar, Kaliganj and Assasuni Upazilla of Satkhira district encroach forest lands and its resources to earn their living. Hill forests in the Chittagong region and other forest areas in different parts of Bangladesh are logged to build housing for the country's exploding population.

The vast region of unbroken green that surrounds the Amazon river and its tributaries in the other part of the world or the coastal land surrounding the Sunderbans and the Rangamati forest areas of have been under assault by settlers and developers. True, time and again forests have defied the prediction that they were doomed. But the dangers are now real and imminent as loggers level trees, dams flood vast areas and shrimp cultivation in coastal lands claims land under forest cover.

The Bangladesh part of the Sunderbans spans about 6000 square kilometers, including a water area of about 1700 square kilometers. There is hardly a doubt in the researcher's claim that here might be hidden a variety of life forms that are yet to be catalogued. Researchers rarely brave trips to the densely-packed forest areas, teeming with wildlife, in absence of a suitable and safe river transport system in the interior forest lands. Yet loggers are reaching these parts, cutting down trees, destroying the very resources that support human life. Consequently, the forest area and the life forms that depend on them are disappearing at a faster rate than ever before. Most settlers find that the lush promise of the Amazon or the Sunderbans or the forest lands of Chittagong is fast becoming an illusion.

Too little too late
After years of inattention, the whole world has awakened at last to the magnitude of what is at stake in the regions like Amazon in Brazil, Indonesia, India or the Sundarbans and hill forests in Bangladesh.

Happily, scientists, environmentalists, print and electronic media persons have journeyed to the endangered areas to marvel and despair at the immolation of these forest resources. These committed groups have become the front lines in the battle to rescue the earth's endangered environment from humanity's destructive ways. "Save the forest" -- long a rallying cry for conservationists -- is now being heard from politicians to film stars. Sadly, the movement has sparked a confrontation between rich industrial nations, which are fresh converts to the environmental cause, and the poor nations of the Third World, which view outside interference as an assault on their sovereignty, creating a stalemate situation in biologically diverse and forest-rich regions of the world.

We can ill-afford to wait for this situation to lift. The destruction of rain forest in the Amazon or the mangrove forest in the Sunderbans portends an incalculable disaster for all of us on planet Earth. Most tropical and mangrove forests are distinguished by their canopies of interlocking leaves and branches that shelter creatures below from sun and wind and their incredible variety of animal and plant life. If the forests perish, so will more than 1 million species, a significant part of the earth's biological diversity and genetic heritage.

Researchers estimate if the current rate of habitat destruction were to continue in forests and coral reefs, half the species of plants and animals would be gone by the end of the 21st century. Our descendants would inherit a biologically impoverished and homogenized world. Not only would there be many fewer life forms, but also faunas and floras would look much the same over large parts of the world, with disaster species such as fire ants and house mice widely spreading. Humanity would then have to wait millions of years for natural evolution to replace what was lost in a single century. Then again, climate change may have already extinguished the very resources on which human life depend.

Md Asadullah Khan is a former teacher of physics and Contooller of Examination, BUET.