Indian Rainforests

An article by Mohan Pai

The Indian Rainforests

Rainforests - the Lungs of the Planet Earth

Tropical rainforests are vital to the global ecosystem and human existence. They are a world like no other and are unparalleled in terms of their biological diversity. Tropical rainforests are a natural reservoir of genetic diversity which offers a rich source of medicinal plants, high-yield foods, and a myriad of other useful forest products. They are an important habitat for migratory animals and sustain as much as 50 percent of the species on Earth, as well as a number of diverse and unique indigenous cultures. Tropical rainforests play an elemental role in regulating global weather in addition to maintaining regular rainfall, while buffering against floods, droughts, and erosion. They store vast quantities of carbon, while producing a significant amount of the world's oxygen. Rainforests once covered 14% of the earths surface and even though they now only cover 6% of the earth, they are home to almost half of the worlds population of mammals, amphibians, reptiles, insects, bird life and plant life.

Tropical rainforests are located in a band around the equator (Zero degrees latitude) in the area between the Tropic of Cancer (23.5° North latitude) and the Tropic of Capricorn (23.5° South latitude).This 3,000 mile (4800 kilometres) wide band is known as the 'tropics'.

The equator is a line that circles the centre of our global world and is situated halfway between the north and south poles. Temperatures at the equator are high. These high temperatures cause accelerated evaporation of water, which results in frequent rain in rainforests in the tropics.

World Rainforests

Tropical rainforests are found between latitudes 10° N and 10° S. This includes the Amazon Basin of South America, the Zaire Basin of Africa and the islands and peninsulas of South-east Asia.In Southeast Asia, the tropical rainforests are found in India, Bangladesh, Sri Lanka, Malaysia, Brunei, Indonesia, Burma and Papua New Guinea. The rainforests found in India, Bangladesh and Sri Lanka are in small patches and strips, while on the other hand, Indonesia contains one-tenth of the world’s rainforest and 40% of all Asian rainforests! However sadly, as Indonesia is progressing further into modernisation, it is losing its rainforests to commercial logging and human settlements. Malaysia too has lost about two third of its lowland forest to plantations. On a brighter side, Papua New Guinea still has areas of rainforest yet to be disturbed, due to its mountainous terrain. Papua New Guinea is home to many amazing animals, one being the largest butterfly in the world; the Queen Alexandra’s birdwing. Its wing span can reach up to 10 inches wide!

Although they cover less than 2 percent of Earth's surface, they house an estimated 50 percent of all life on the planet. The immense numbers of creatures that inhabit the tropical rainforests are so great—an estimated 50 million species— they are almost incomprehensible. The sheer range of numbers alone suggests the limited extent of our knowledge of these forests. For example, whereas temperate forests are often dominated by a half dozen tree species or fewer that make up 90 percent of the trees in the forest, a tropical rainforest may have more than 480 tree species in a single hectare (2.5 acres). A single bush in the Amazon may have more species of ants than the entire British Isles. This diversity of rainforests is not a haphazard event, but is the result of a series of unique circumstances.

Layers

A tropical rainforest is typically divided into four main layers, each with different plants and animals adapted for life in that particular area: the emergent, canopy, understory, and forest floor layers.

Emergent layer

The emergent layer contains a small number of very large trees called emergents, which grow above the general canopy, reaching heights of 45-55 m, although on occasion a few species will grow to 70-80 m tall. They need to be able to withstand the hot temperatures and strong winds in some areas. Eagles, butterflies, bats, and certain monkeys inhabit this layer.

Diagram: Coutesy Animal Corner

Canopy layer

The canopy layer contains the majority of the largest trees, typically 30-45 m tall. The densest areas of biodiversity are found in the forest canopy, a more or less continuous cover of foliage formed by adjacent treetops. The canopy, by some estimates, is home to 50 percent of all plant species, suggesting that perhaps half of all life on Earth could be found there. Epiphytic plants attach to trunks and branches, and obtain water and minerals from rain and debris that collects on the supporting plants. The fauna is similar to that found in the emergent layer, but more diverse. A quarter of all insect species are believed to exist in the rainforest canopy. Scientists have long suspected the richness of the canopy as a habitat, but have only recently developed practical methods of exploring it. As long ago as 1917, naturalist William Beebe declared that "another continent of life remains to be discovered, not upon the Earth, but one to two hundred feet above it, extending over thousands of square miles." True exploration of this habitat only began in the 1980s, when scientists developed methods to reach the canopy, such as firing ropes into the trees using crossbows. Exploration of the canopy is still in its infancy, but other methods include the use of balloons and airships to float above the highest branches and the building of cranes and walkways planted on the forest floor. The science of accessing tropical forest canopy using airships, or similar aerial platforms, is called dendronautics.

Understory layer

The understory layer lies between the canopy and the forest floor. The understory (or understorey) is home to a number of birds, snakes, and lizards, as well as predators such as jaguars, boa constrictors, and leopards. The leaves are much larger at this level. Insect life is also abundant. Many seedlings that will grow to the canopy level are present in the understory. Only about 5 percent of the sunlight shining on the rainforest reaches the understory. This layer can also be called a shrub layer, although the shrub layer may also be considered a separate layer.

Forest floor

The forest floor, the bottom-most layer, receives only 2 percent of sunlight. Only plants adapted to low light can grow in this region. Away from riverbanks, swamps, and clearings

where dense undergrowth is found, the forest floor is relatively clear of vegetation because of the low sunlight penetration. It also contains decaying plant and animal matter, which disappears quickly due to the warm, humid conditions promoting rapid decay. Many forms of fungi grow here which help decay the animal and plant waste. It takes up to 20 minutes for rain to actually touch the ground from the trees. Forest floor - Mahadayi Valley, Karnataka.

Because of the ample solar energy, tropical rainforests are usually warm year round with temperatures from about 72-93F (22-34C), although forests at higher elevations, especially cloud forests, may be significantly cooler. The temperature may fluctuate during the year, but in some equatorial forests the average may vary as little as 0.5F (0.3C) throughout the year. Temperatures are generally moderated by cloud cover and high humidity.

PRECIPITATION
An important characteristic of rainforests is apparent in their name. Rainforests lie in the intertropical convergence zone where intense solar energy produces a convection zone of rising air that loses its moisture through frequent rainstorms. Rainforests are subject to heavy rainfall, at least 80 inches (2,000 mm), and in some areas over 430 inches (10,920 mm) of rain each year. In equatorial regions, rainfall may be year round without apparent "wet" or "dry" seasons, although many forests do have seasonal rains. Even in seasonal forests, the period between rains is usually not long enough for the leaf litter to dry out completely. During the parts of the year when less rain falls, the constant cloud cover is enough to keep the air moist and prevent plants from drying out. Some neotropical rainforests rarely go a month during the year without at least 6" of rain. The stable climate, with evenly spread rainfall and warmth, allows most rainforest trees to be evergreen—keeping their leaves all year and never dropping all their leaves in any one season. Forests further from the equator, like those of India, Thailand, Sri Lanka, and Central America, where rainy seasons are more pronounced, can only be considered "semi-evergreen" since some species of trees may shed all of their leaves at the beginning of the dry season. Annual rainfall is spread evenly enough to allow heavy growth of broad-leafed evergreen trees, or at least semi-evergreen trees. The moisture of the rainforest from rainfall, constant cloud cover, and transpiration (water loss through leaves), creates intense local humidity. Each canopy tree transpires some 200 gallons (760 liters) of water annually, translating to roughly 20,000 gallons (76,000 L) of water transpired into the atmosphere for every acre of canopy trees. Large rainforests (and their humidity) contribute to the formation of rain clouds, and generate as much as 75 percent of their own rain.

The Amazon rainforest is responsible for creating as much as 50 percent of its own precipitation. Deforestation and climate change may be affecting the water cycle in tropical rainforests. Since the mid-1990s, rainforests around the world have experienced periods of severe drought, including southeast Asia in 1997 and 2005 and the Amazon in 2005. Dry conditions, combined with degradation from logging and agricultural conversion, make forests more vulnerable to wildfire.

Rainforests Waters

Tropical rainforests have some of the largest rivers in the world, like the Amazon, Madeira, Mekong, Brahmaputra, Negro, Orinoco, and Zaire (Congo), because of the tremendous amount of precipitation their watersheds receive. These mega-rivers are fed by countless smaller tributaries, streams, and creeks. For example, the Amazon alone has some 1,100 tributaries, 17 of which are over 1,000 miles long. Although large tropical rivers are fairly uniform in appearance and water composition, their tributaries vary greatly. Many tropical rivers and streams have extreme high and low water levels that occur at different parts of the year. In addition to rivers, rainforests have conventional, free-standing lakes and so-called oxbow lakes, formed when a river changes course. These lakes are home to species adapted to the quiet, stagnant conditions. Tropical waters, whether they be giant rivers, streams, or oxbow lakes, are almost as rich in animal species as the rainforests that surround them. But they, too, are increasingly threatened by human activities, including pollution, siltation resulting from deforestation, hydroelectric projects, and over-harvesting of resident species.

Forest - the mother of rivers
There is an umbilical connection between healthy forests and water regimes. Forests are nurseries and cisterns for our life giving rivers. Forest areas give birth to all the major and minor rivers. Most of the rivers spring from some unknown forests. Because of the slope the rain water cannot stay to soak into the earth, it flows downhill rapidly taking some of the earth with it This run-off on the hillsides will only be halted, and water will percolate into the earth where there is a good tree cover. In fact a forest “traps” rainwater and channels it into underground streams.

World’s Largest Pharmacy

Medicinal plants and herbs which are in great demand by Pharmaceutical MNCs e.g. Mappia foetida used for the treatment of ovarian colon cancers. The tree is the richest source of Camptothetician (CPT) used in the treatment of these cancers.

Tropical rainforests are called "the world's largest pharmacy" because of the large amount of natural medicines discovered in rainforests that are derived from rainforest plants. For example, rain forests contain the basic ingredients of hormonal contraception methods, cocaine, stimulants, and tranquilizing drugs. Curare (a paralyzing drug) and quinine (a malaria cure) are also found there.

CONSEQUENCES OF DEFORESTATION
Rainforests around the world still continue to fall. Does it really make a difference? Why should anyone care if some plants, animals, mushrooms, and microorganisms perish? Rainforests are often hot and humid, difficult to reach, insect-ridden, and have elusive wildlife.

Actually the concern should not be about losing a few plants and animals; mankind stands to lose much more. By destroying the tropical forests, we risk our own quality of life, gamble with the stability of climate and local weather, threaten the existence of other species, and undermine the valuable services provided by biological diversity. While in most areas environmental degradation has yet to reach a crisis level where entire systems are collapsing, it is important to examine some of the effects of existing environmental impoverishment and to forecast some of the potential repercussions of forest loss. Continuing loss of natural systems could make human activities increasingly vulnerable to ecological surprises in the future. The most immediate impact of deforestation occurs at the local level with the loss of ecological services provided by tropical rainforests and related ecosystems. Such habitats afford humans valuable services such as erosion prevention, flood control, water treatment, fisheries protection, and pollination—functions that are particularly important to the world's poorest people, who rely on natural resources for their everyday survival. Forest loss also reduces the availability of renewable resources like timber, medicinal plants, nuts and fruit, and game. Over the longer term, deforestation of tropical rainforests can have a broader impact, affecting global climate and biodiversity. These changes are more difficult to observe and forecast from local effects, since they take place over a longer time scale and can be difficult to measure.

Deforestation and the Global Carbon Cycle

Carbon dioxide ( CO2) is the major gas involved in the greenhouse effect, which causes global warming. All the things that produce CO2 (like car burning gas) and the things that consume Co2 (growing plants) are involved in the “global carbon cycle”. Tropical forests hold an immense amount of carbon, which joins with oxygen to form CO2. The plants and soil of tropical forests hold 460-575 billion metric tons of carbon worldwide. Each acre of tropical forest stores about 180 metric tons of carbon.

Deforestation increases the amount of CO2 and other trace gases in the atmosphere. When a forest is cut and replaced by cropland and pastures, the carbon that was stored in the tree trunks (wood is about 50% carbon) joins with oxygen and is released into the atmosphere as Co2.The loss of forests has a great effect on the global carbon cycle. From 1850 to 1990, deforestation worldwide (including that in the United States) released 122 billion metric tons of carbon into the atmosphere, with the current rate being 1.6 billion metric tons per year. In comparison all the fossil fuels (coal, oil and gas) burned during a year release about 6 billion tons per year.Releasing CO2 into the atmosphere increases the greenhouse effect, and may raise global temperature. The role of fossil fuels burned by cars and industry is well known, but tropical deforestation releases about 25% of the amount released by fossil fuel burning. Tropical deforestation, therefore, contributes a significant part of the increasing CO2 in the atmosphere.

Today tropical rainforests are disappearing from the face of the globe. Despite growing international concern, rainforests continue to be destroyed at a pace exceeding 80,000 acres (32,000 hectares) per day. World rainforest cover now stands at around 2.5 million square miles (6 million square kilometers), an area about the size of the contiguous 48 United States or Australia and representing around 5 percent of the world's land surface. Much of this remaining area has been impacted by human activities and no longer retains its full original biodiversity.

The Rainforests of India

The rainforests in India are the centres of species richness and endemism and due to this has the status of being one of the 12 mega-biodiversity countries in the world. Even the two hotspots in India, the Western Ghats and the Eastern Himalayas, owe their status due to the presence of rainforests therein. These forests form very important catchments areas for major river systems, maintain soil and water fertility not only in the immediate vicinity but also hundreds of kilometers away, harbours rich indigenous culture with long traditions of sustainable use of traditional knowledge systems especially on medicines and wild relatives of cultivate crops. It is to these rainforests that more than 80% of the endemic flora and fauna of India are confined. Being the most complex ecosystem, the rain forests are living laboratories in which complex ecological, biological and evolutionary processes that have shaped the Earth.

Bamboo brakes, Muthodi, Karnataka

Tropical forest cover in India has been reduced to two major areas: the coastal hills of the Western Ghats (about 55,000 square miles or 135,000 sq. km) and 14,000 square miles (34,500 sq. km) in Northeastern India. Very little of India's forest cover is considered pristine. 22.8% —or about 67,701,000 hectares—of India is forested. Change in Forest Cover: Between 1990 and 2000, India gained an average of 361,500 hectares of forest per year. The amounts to an average annual reforestation rate of 0.57%. Between 2000 and 2005, the rate of forest change decreased by 92.3% to 0.04% per annum. In total, between 1990 and 2005, India gained 5.9% of its forest cover, or around 3,762,000 hectares. Measuring the total rate of habitat conversion (defined as change in forest area plus change in woodland area minus net plantation expansion) for the 1990-2005 interval, India gained 1.0% of its forest and woodland habitat.Biodiversity and Protected Areas: India has some 2356 known species of amphibians, birds, mammals and reptiles according to figures from the World Conservation Monitoring Centre. Of these, 18.4% are endemic, meaning they exist in no other country, and 10.8% are threatened. India is home to at least 18664 species of vascular plants, of which 26.8% are endemic. 4.9% of India is protected under IUCN categories I-V.

The Rainforests of the Western Ghats

The Western Ghats hill range in India contains spectacular landscapes and an incredible array of wild species, many found nowhere else in the world. One among the world’s 34 most biologically diverse “hotspots”, the region has representation of a wide variety of natural ecosystems from grasslands and dry forests to rainforests, rivers, and streams, threatened by a multitude of human activities such as industrialisation, agriculture, grazing, hunting, deforestation, fragmentation, and degradation. Today, rainforests in the Western Ghats occur largely as fragments within a landscape matrix dominated by commercial plantations of tea, coffee, and other cash crops. With an annual deforestation rate of 1.2%, the southern Western Ghats is losing about 500 square kilometres of forest every year. NCF’s programme focuses on human impacts on wild species and habitats, biological surveys, human-wildlife conflict research and mitigation, and restoration to turn the tide of destruction towards conservation.

Forests of the western slopes of the Western Ghats, Konkan
The northern portion of the range is generally drier than the southern portion, and at lower elevations makes up the North Western Ghats moist deciduous forests ecoregion, with mostly deciduous forests made up predominantly of teak. Above 1,000 meters elevation are the cooler and wetter North Western Ghats montane rain forests, whose evergreen forests are characterized by trees of family Lauraceae.The evergreen Wayanad forests of Kerala mark the transition zone between the northern and southern ecoregions of the Western Ghats. The southern ecoregions are generally wetter and more species-rich. At lower elevations are the South Western Ghats moist deciduous forests, with Cullenia the characteristic tree genus, accompanied by teak, dipterocarps, and other trees. The moist forests transition to the drier South Deccan Plateau dry deciduous forests, which lie in its rain shadow to the east.

Clear felling, Mahadayi Valley, Karnataka

Above 1,000 meters are the South Western Ghats montane rain forests, also cooler and wetter than the surrounding lowland forests, and dominated by evergreen trees, although some montane grasslands and stunted forests can be found at the highest elevations. The South Western Ghats montane rain forests are the most species-rich ecoregion in peninsular India; eighty percent of the flowering plant species of the entire Western Ghats range are found in this ecoregion.

Tropical Montane - Bedthi River Valley, Karnataka

The animal life of the Indian peninsular region is characterised by the absence of many of the Indo-Malay species which are so abundant in the hill forests of the Himalayas. It is the home of the true Indian fauna of which the spotted deer, the nilgai, the blackbuck, the four-horned antelope, and the sloth bear are typical representatives. They are found no where else. Other species like the gaur, the sambar and the muntjac (barking deer) occur both in India and Malay countries. The Western Ghats, in sharp contrast to the adjoining dry zone of the Deccan present a region of great humidity and heavy rainfall. The forests covering the western slopes are at times very dense and composed of lofty trees, festooned with perennial creepers. Bamboos form a luxuriant undergrowth. In parts of the range the forests are more open and the banks of clear streams running through them are covered with spice and betel groves.
The Nilgiris, an offshoot of the Western Ghats, rise precipitously to form extensive grassy downs and tablelands seamed with densely forested gorges or Sholas. They are composed of evergreen trees with dense undergrowth.








1. Malabar Giant Squirrel 2. Lion tailed Macaque

Among the species limited to these forests are the Nilgiri langur, the Lion-tailed macaque, the Nilgiri brown mongoose and the striped necked mongoose, the Malabar civet, and the spiny mouse. In the higher levels of the Nilgiris and the Anaimalais are found such characteristically Himalayan animals as the tahr, the pine marten and the European otter.

Endemic species of the Western Ghats
One hundred and twenty species of mammals are known from the Western Ghats of which fourteen species are endemic (found only in that area).

Nilgiri Tahr

The mammalian fauna of the Western Ghats is dominated by insectivores (11 species), bats (41 species) and rodents (27 species including porcupine). Few studies have, however, paid attention to the community structure and organisation of these small mammals in the Western Ghats, although there have been attempts to review our understanding of the status and ecology of smaller cats and lesser carnivores.

The Rainforests of the Northeast India

The Northeast India lying between 22-30 degree N latitude and 89-97 degree E longitude, and sprawling over 2,62,379 sq.km., Northeast India represents the transition zone between the Indian, Indo-Malayan and Indo-Chinese biogeographic regions and a meeting place of the Himalayan Mountains and Peninsular India. It was the part of the northward migrating ‘Deccan Peninsula’ that first touched the Asian landmass after the break up of Gondwanaland in the early Tertiary Period. Northeast India is thus the geographical ‘gateway’ for much of India’s flora and fauna, and as a consequence, the region is one of the richest in biological values. It is in this lowland-highland transition zone that the highest diversity of biomes or ecological communities can be found, and species diversities within these communities are also extremely high.

Northeast India is blessed with a wide range of physiography and ecoclimatic conditions. The State of Assam has extensive flood plains, while Khangchendzonga in Sikkim stands 8586 m. tall. Cherrapunjee in the State of Meghalaya holds the record for the highest rainfall in a single month (9,300 mm) as well as the most in a year (26,461 mm) in India, while the nearby Mawsynram has the world’s highest average rainfall (11,873 mm). The forests in the region are extremely diverse in structure and composition and combine tropical and temperate forest types, alpine meadows and cold deserts. There are regions, for example, in the State of Sikkim, where the faunal assemblages also change rapidly from tropical to subtropical, temperate, alpine and finally to cold desert forms.

After the Andaman and Nicobar Islands and the Western Ghats, Northeast India forms the main region of tropical forests in India, especially the species-rich tropical rain forests. The tropical semi-evergreen and moist deciduous forests in the lowlands of this region extend south and west into the subcontinent, and east into Southern China and Southeast Asia. The subtropical forests of the region follow the foothills of the Himalaya to the west; also extend into Southeast China in the east. Himalayan temperate and subalpine zone forests extend from northern Pakistan and adjacent Afghanistan through Northeast India to Southwest China. Each of the eight States of the region, namely Arunachal Pradesh, Assam, Meghalaya, Manipur, Mizoram, Nagaland, Sikkim and Tripura, boast of several endemics in flora as well as fauna. This region represents an important part of the Indo-Myanmar biodiversity hotspot.

1. Dooars forests, North Bengal 2. Golden Langur

The primary vegetation in extensive areas of the Northeast India has been disturbed and modified and in some places destroyed by seismic activities, frequent landslides and resultant soil erosion. While these natural causes have contributed only marginally to the change in vegetation type, it is the activity of Man that has led to the irreversible transformation in the landscapes and has resulted in colossal loss of biodiversity in the entire region. Human influences have pushed many species to the brink of extinction and have caused havoc to natural fragile ecosystems. Such devastations to natural ecosystems are witnessed almost everywhere in the region and is a cause of great concern.

1. Slow Loris 2. Reticulated Python

Northeast India has 64% of the total geographical area under forest cover and it is often quoted that it continues to be a forest surplus region. However, the forest cover is rapidly disappearing from the entire region. There has been a decrease of about 1800 sq.km. in the forest cover between 1991 and 1999. More worrisome still is the fact that the quality of the forest is also deteriorating, with the dense forests (canopy closure of 40% or more) becoming degraded into open forest or scrub. Though there is a succession of several edaphic formations, a vast area of land has already been transformed into barren and unproductive wastelands. This being the case, the statistics of ‘more than 64 % of the total geographic area in this region under forest cover’ could be misleading. For example, though the forest cover in Manipur extends to 78% of the total geographic area, only 22% of forest area is under dense forest cover and the rest has been converted to open forests.

Except in the Brahmaputra and Barak valleys of Assam where substantial areas are under agriculture, little of the land is available for settled cultivation. Hence, shifting agriculture or slash-and-burn agriculture is the major land use in Northeast India and extends over 1.73 million ha. Different agencies have come up with different figures concerning the total area under shifting cultivation (jhum) in the region. What is not disputable is that with an ever shortening jhum cycle, the other human influences have caused environmental degradation with disastrous consequences.The forests of Assam once acted as a sponge, absorbing the tremendous impact of the monsoons. The natural drainage of the vast northeastern Himalaya is channelled through Assam and with the loss of thick forest cover, Brahmaputra, one of the largest and fastest flowing rivers of the subcontinent is creating havoc in the State. Floods that have devastating effects are now common to Northeast India and protecting the forests is a difficult problem.

The Rainforests of the Andamans & Nicobar Islands

The Andamans and Nicobar Islands have tropical evergreen rain forests and tropical semi-evergreen rainforests as well as tropical monsoon moist monsoon forests.

There are 572 islands in the territory, of which only approximately 38 are permanently inhabited. Most of the islands (about 550) are in the Andamans group, 26 of which are inhabited. The smaller Nicobars comprise some 22 main islands (10 inhabited). The Andamans and Nicobars are separated by a channel (the Ten Degree Channel) some 150 km wide.The total area of the Andaman Islands is some 6,408 km²; that of the Nicobar Islands approximately 1,841 km².

Aerial view -Andamans & Nicobar Islands

Andaman & Nicobar Islands are blessed with a unique tropical rainforest canopy, made of a mixed flora with elements from Indian, Myanmarese, Malaysian and endemic floral strains. So far, about 2,200 varieties of plants have been recorded, out of which 200 are endemic and 1,300 do not occur in mainland India.The South Andaman forests have a profuse growth of epiphytic vegetation, mostly ferns and orchids. The Middle Andamans harbours mostly moist deciduous forests. North Andamans is characterised by the wet evergreen type, with plenty of woody climbers. The north Nicobar Islands (including Car Nicobar and Battimalv) are marked by the complete absence of evergreen forests, while such forests form the dominant vegetation in the central and southern islands of the Nicobar group. Grasslands occur only in the Nicobars, and while deciduous forests are common in the Andamans, they are almost absent in the Nicobars. The present forest coverage is claimed to be 86.2% of the total land area.

References: Wikipedia, Mongabay,com, Animal corner.com, The Western Ghats by Mohan Pai, Nature Conservation Foundation, Biodiversity of Northeast India an Overview -V.Ramakantha, A.K.Gupta, Ajith Kumar

For more information log on to:

http://rainforests.mongabay.com/

http://www.animalcorner.co.uk/rainforests/rainforests.html

Bamboo - the Grass of Heaven

An article by Mohan Pai

Bamboo - the Grass of Heaven

(Bambusa)

Is Bamboo a tree or grass ?

The Bamboo is one of the most fascinating plants on the earth but is Bamboo a tree or grass ? Indian Forest Act 1927 under section 2(7) has defined the bamboo as a tree ! The bamboos are a group of woody perennial plants in the true grass family Poaceae, subfamily Bamboosoideae, tribe Bambuseae. Some are giant bamboos, the largest member of grass family.
To a layman all bamboos look alike but actually there are more than 70 genera divided into about 1000 different kinds species in the world. Because of their large size these arborescent grasses are also called ‘elder brother of grasses’. Bamboos have age-old connections with the material needs of man and are fascinating to the artist, the poet, the craftsman and the scientist. Aptly called the ‘poor man’s timber’ bamboos are of great importance to the people of the East where they are found in greatest abundance and variety. Several Asian cultures, including that of the Andaman islands, believe thatHumanity has emerged from the bamboo stem. They are of considerable economic and high cultural significance in East Asia and South East Asia where they are used extensively in gardens, as building material, and as a food source.

Bamboos are the fastest growing woody plants in the world. Their growth rate (up to 60 centimeters (24 in.) a day) is due to a unique rhizome-dependent system, but is highly dependent on local soil and climate conditions.

The Bamboo in India

While 150 species are found in the Indian subcontinent, India alone accounts for more than 115. Spread over an area of 10 million hectares or 13 per cent of the total forest area of the country, perhaps the world’s largest reserves of bamboos consisting of over 115 species both wild and cultivated exist in India; areas particularly rich being the northeast region and the Western Ghats. The bamboos in India have a wide range of distribution and found in all parts of the country except in Kashmir valley.
As an understorey they form rich belts of vegetation in well-drained parts of tropical and subtropical habitats and grow up to 3,700 m in the Himalayas. The distribution of bamboos, however, has been greatly altered by human intervention and natural stands have at places been more or less cleared off for shifting cultivation. The other intervention comes from the paper industry which cuts or grows bamboos according to its needs.

Garden variety

The structural foundation of the plant is the underground, segmented and condensed rhizomes which goes on propagating vegetatively. The arterial part (stem) is called the culm and several culms arising out of the ramifications of the rhizome are collectively called the clump. Bamboo-culms are branched at the nodes. The branches are sometimes spiny as in the case of Spiny bamboo. Depending on the species they may be mere shrubs with culms no thicker than a pencil as most hill bamboos are, or they may become giants reaching a height of 37 m and a diameter of more than 0.25 m as in the case of the Giant bamboo of Burma, which is cultivated at Dehra Dun and some other places. Whereas most of the bamboos are erect, quite a few are scramblers and even climbers, stretching over the crowns of tall forest trees.
Nearly all species are green when fresh but some like the pantropical Tiger bamboo are of a beautiful golden colour with green stripes or otherwise variegated. An occasional species has near black colour. Most species have hollow culms but some like the Male bamboo (so called because of its strength) - have solid culms.

Growth

Bamboo is the fastest-growing plant on Earth; it has been measured surging skyward as fast as 121 cm (47.6 inches) in a 24-hour period and can also reach maximal growth rate exceeding one meter (39 inches) per hour for short periods of time. Many prehistoric bamboos exceeded heights of 75 meters (250 feet). Primarily growing in regions of warmer climates during the Cretaceous, vast fields existed in what is now Asia. Modern bamboos can only sustain their maximal growth rate for short periods of time.

Unlike trees, all bamboos grow to full height and girth in a single growing season of 3–4 months. During this first year the young shoots strike skyward supported by photosynthesis from the rest of the clump with no time to sprout their own branches and leaves. Over the next year the pulpy wall of each culm slowly dries and hardens, sprouting branches and leaves during the second year from juvenile sheathes that form from each node. Over the following year the culm hardens still further shedding its juvenile sheaths and commencing its life as a fully mature culm. over the next 2–5 years depending on species, fungus and mould begin to form on the outside of the culm, eventually penetrating and overcoming the culm so that by around 5 – 8 years depending on species and climate the culms begin to collapse and decay. This brief life means culms are ready for harvest and suitable for use in construction from 3-5 or 7 years.

Mass flowering

Although some bamboos flower every year, most species flower infrequently. In fact, many bamboos only flower at intervals as long as 60 or 120 years. These taxa exhibit mass flowering (or gregarious flowering), with all plants in the population flowering simultaneously. The longest mass flowering interval known is 130 years, and is found for all the species Phyllostachys bambusoides. In this species, all plants of the same stock flower at the same time, regardless of differences in geographic locations or climatic conditions, then the bamboo dies. The lack of environmental impact on the time of flowering indicates the presence of some sort of “alarm clock” in each cell of the plant which signals the diversion of all energy to flower production and the cessation of vegetative growth. This mechanism, as well as the evolutionary cause behind it, is still largely a mystery.One theory to explain the evolution of this semelparous mass flowering is the predator satiation hypothesis. This theory argues that by fruiting at the same time, a population increases the survival rate of their seeds by flooding the area with fruit so that even if predators eat their fill, there will still be seeds left over. By having a flowering cycle longer than the lifespan of the rodent predators, bamboos can regulate animal populations by causing starvation during the period between flowering events. Thus, according to this hypothesis, the death of the adult clone is due to resource exhaustion, as it would be more effective for parent plants to devote all resources to creating a large seed crop than to hold back energy for their own regeneration.A second theory, the fire cycle hypothesis, argues that periodic flowering followed by death of the adult plants has evolved as a mechanism to create disturbance in the habitat, thus providing the seedlings with a gap to grow in. This hypothesis argues that the dead culms create a large fuel load, and also a large target for lightning strikes, increasing the likelihood of wildfire. Because bamboos are very aggressive as early successional plants, the seedlings would be able to outstrip other plants and take over the space left by their parents.However, both have been disputed for different reasons. The predator satiation theory does not explain why the flowering cycle is 10 times longer than the lifespan of the local rodents, something not predicted by the theory. The bamboo fire cycle theory is considered by a few scientists to be unreasonable because, as argued by fires only result from humans and there is no natural fire in India. This notion is considered wrong based on distribution of lightning strike data during the dry season throughout India.

The mass fruiting also has direct economic and ecological consequences, however. The huge increase in available fruit in the forests often causes a boom in rodent populations, leading to increases in disease and famine in nearby human populations. For example, there are devastating consequences when the Melocanna bambusoides population flowers and fruits once every 30–35 years around the Bay of Bengal. The death of the bamboo plants following their fruiting means the local people lose their building material, and the large increase in bamboo fruit leads to a rapid increase in rodent populations. As the number of rodents increase, they consume all available food, including grain fields and stored food, sometimes leading to famine. These rats can also carry dangerous diseases such as typhus, typhoid, and bubonic plague, which can reach epidemic proportions as the rodents increase in number.

Woven Basket from Bamboos

Poor Man’s Timber

The number of ways bamboos enter into the diverse phases of human life is astonishing. It has been said that these giant grasses are one of those providential developments in nature which, like the horse, the cow, wheat and cotton, have been indirectly responsible for man’s own revolution. Bamboo is a material that is sufficiently cheap and plentiful to meet the vast needs of the human population - from the child’s cradle to the dead man’s bier.

Bamboo House

Role of Bamboo

The qualities which make bamboo so versatile are the strength of culms, their straightness, lightness combined with hardness, range in size, abundance, , easy propagation, and the short period in which they attain maturity. The culms can be easily split with ordinary hand tools. In the humid tropics whole houses are built entirely of bamboo without using a single nail; huge suspension bridges made solely of canes and bamboos are marvels of indigenous engineering skill typical of tribal expertise. In fact there is no limit to the varieties of articles that can be made out of the bamboo.
Thomas Edison had used the carbonized filament of bamboo for his early electric lamps; the razor sharp peel has been, at times used in place of the surgical knife.
Chinese wood carving - late Qing Dynasty

Among the more sophisticated uses of the Bamboo are the manufacture of a large variety of writing papers, charcoal for electric batteries, liquid diesel fuel obtained by distillation, enzymes and media for culturing pathogenic bacteria from shoot extracts and the white powder produced on the outer surface of young stems for the isolation of crystalline compound similar in nature for female sex hormones. Tabasheer or banslochan, the fine siliceous matter deposited in the hollow stems of some species, has excellent properties as a catalyst for certain chemical reactions, though in the subcontinent it is prized as a restorative tonic and aphrodisiac.

Another aphrodisiac use, though nefarious one, is attributed to the rhizome of Rhino bamboo (D. Hamiltonii) which is an exact replica of a rhinoceros horn that fetches a fabulous price; only an expert perhaps can identify the imitation rhino horn from the real. Recently a new use of bamboo, ‘Bamboo reinforced cement concrete construction’, has been evolved where bamboos have been used as reinforcing material replacing steel in the construction of roof-slabs, beams, electric posts, etc.

Bamboo, the main diet of the Giant Panda

Bamboo are used for thatching and are also valued as fodder; elephants in particular are fond of it. The Giant Panda’s diet is entirely made up of bamboo leaves. Dried and matured leaves are also used for deodorising fish oil. Bamboo sheaths are used in lining of hats and sandals. As a popular ornamental, bamboo is used for hedges and in landscape gardening. It is valuable as a wind-break and is particularly useful for preventing soil erosion on account of its interwoven root system.

Culinary Uses

The shoots (new bamboo culms that come out of the ground) of bamboo are edible and most popular and relished food in Chinese and Asian Cooking. They are used in numerous Asian dishes and broths, and are available in supermarkets in various sliced forms, both fresh and canned version.The bamboo shoot in its fermented state (called khorisa) forms an important ingredient in the cuisine of Assam.In Indonesia, they are sliced thin and then boiled with santan (thick coconut milk) and spices to make a dish named gulai rebung. Other recipes using bamboo shoots are sayur lodeh (mixed vegetables in coconut milk) and lun pia (sometimes written lumpia: fried wrapped bamboo shoots with vegetables). The shoots of some species contain toxins that need to be leached or boiled out before they can be eaten safely.

Pickled bamboo, used as a condiment, may also be made from the pith of the young shoots.The sap of young stalks tapped during the rainy season may be fermented to make ulanzi (a sweet wine) or simply made into a soft drink. Zhúyèqing jiu is a green-coloured Chinese liquor that has bamboo leaves as one of its ingredients.Bamboo leaves are also used as wrappers for zongzi, a steamed dumpling typical of southern China, which usually contains glutinous rice and other ingredients.The empty hollow in the stalks of larger bamboo is often used to cook food in many Asian cultures. Soups are boiled and rice is cooked in the hollows of fresh stalks of bamboo directly over a flame. Similarly, steamed tea is sometimes rammed into bamboo hollows to produce compressed forms of Pu-erh tea. Cooking food in bamboo is said to give the food a subtle but distinctive taste.In Sambalpur, India, the tender shoots are grated into juliennes and fermented to prepare kardi. The name is derived from the Sanskrit word for bamboo shoot, "karira". This fermented bamboo shoot is used in various culinary preparations, notably "amil", a sour vegetable soup. It is also made into pancakes using rice flour as a binding agent. The shoots that have turned a little fibrous are fermented, dried, and grounded to sand size particles to prepare a garnish known as "hendua". It is also cooked with tender pumpkin leaves to make sag green leaves.In addition, bamboo is frequently used for cooking utensils within many cultures.
MedicineBamboo is used in Chinese medicine for treating infections. It is also used for healing. It is also a low calorie source of potassium. It has also been known for its sweet taste and good source of nutrients and protein. In Ayurveda, the Indian system of traditional medicine, the silicious concretion found in the culms of the bamboo stem is called banslochan. It is known as tabashir or tawashir in Unani-Tibb the Indo-Persian system of Medicine. In English this concretion is called "bamboo manna". This concretion is said to be a tonic for the respiratory diseases. This concretion, which was earlier obtained from Melocanna bambusoides is very hard to get now and has been largely replaced by synthetic silcic acid. In most Indian literature, Bambusa arundinacea is described as the source of bamboo manna.


What is lucky bamboo?

'Lucky bamboo' is a popular plant, increasingly available in shops and stores. The plant is probably of West African origin. It is easy to maintain. It thrives without soil in a few inches of water, and requires only a little sunlight to grow. It is however not bamboo. It is Dracenia sanderiana, a member of the lily family.


References Encyclopedia of Indian Natural History (Bombay Natural history Society), Wikipedi