The forest is a complex ecosystem consisting mainly of trees that shield the earth and support innumerable life forms. A forest is an area, which has a very high density of trees. Trees are an important component of the environment. They clean the air, cool it on hot days, conserve heat at night, and act as excellent sound absorbers. Forests create a special environment, which, in turn, affects the kinds of animals and plants that can exist. Forests can develop wherever there is an average temperature greater than about 10° C in the warmest month and an annual rainfall in excess of about 200 mm annually, except where natural fire frequency is too high, or where the environment has been impaired by natural processes or by human activities. In any area having conditions above this range there exists an infinite variety of tree species grouped into a number of stable forest types that are determined by the specific conditions of the environment there. Forests can be broadly classified into many types, some of which are the Taiga type (consisting of pines, spruce, etc.) the mixed temperate forests with both coniferous and deciduous trees, the temperate forests, the sub tropical forests, the tropical forests, and the equatorial rainforests. The six major groups of forest in India are moist tropical, dry tropical, montane sub tropical, montane temperate, sub alpine, and alpine. These are subdivided into 16 major types of forests.

The scientific study of forest species and their interaction with the environment is referred to as forest ecology, while the management of forests is often referred to as forestry. Globally only two types of forests can be identified:

Natural forests, which contain only the original patterns of biodiversity. The native species occurring in established seral patterns. These formations and processes have not been impacted by humans with a frequency or intensity to change established seral patterns, and Anthropogenic forests, which have been impacted by humans with a frequency or intensity to change established seral patterns. Often, they contain elements of exotic species.

Types of Forests:
Climate, soil type, topography, and elevation are the main factors that determine the type of forest. India has a diverse range of forests: from the rainforest of Kerala in the south to the alpine pastures of Ladakh in the north, from the deserts of Rajasthan in the west to the evergreen forests in the northeast. Forests are classified according to their nature and composition, the type of climate in which they thrive, and its relationship with the surrounding environment.

Forests can be classified in other different ways and to different degrees of specificity. One such way is in terms of the "biome" in which they exist combined with leaf longevity of the dominant species (whether they are evergreen or deciduous). Another distinction is whether the forests composed predominantly of broadleaf trees, coniferous (needle-leaved) trees, or mixed. There is no Universally accepted or set principle to classify forests.

Rain Forest:
Rainforests are those forests, which are characterized by high rainfall between 1750mm and 2000mm. Rain forests belong to the tropical wet climate group. The temperature in a rain forest rarely gets higher than 93 °F (34 °C) or drops below 68 °F (20 °C); average humidity is between 77 and 88%; rainfall is often more than 100 inches a year. There is usually a brief season of less rain. Almost all rain forests lie near the equator.

Rainforests are home to two-thirds of all the living animal and plant species on the planet. It has been estimated that many hundreds of millions of new species of plants, insects and microorganisms are still undiscovered. Despite the growth of vegetation in a rainforest, the actual quality of the soil is often quite poor. Rapid bacterial decay prevents the accumulation of humus. The undergrowth in a rainforest is restricted in many areas by the lack of sunlight at ground level. This makes it possible for people and other animals to walk through the forest. Rainforests may also play a role in cooling air that passes through them. As such, rainforests are of vital importance within the global climate system. Rainforests support a very broad array of fauna including mammels, birds, reptiles like snakes, turtles, chameleons and others of the family. More than half of the world`s species of plants and animals are found in the rainforest. Insects, including brightly colored butterflies, mosquitoes, camouflaged stick insects, and huge colonies of ants make up the largest group of the rainforests.

Black Forest:
These are the Silent forests found in Germany. Covering nearly 160 km (100 miles) across southwest Germany, these Black Forests are the country`s largest national park. These forests have served as a source of timber and fuel wood, for hunting of animals, as watersheds for clean water, and for recreation. The Black Forest is abundant in its commercially valuable spruce tree, fir and other species of trees. But growing of a well planned, commercially structured and well-spaced valuable trees has reduced the structural diversity of the forest and old-growth forest conditions. Because of this commercialization, much of the previously abundant wildlife, which depended on these dense forests, has become very less common. The intensive forest management also has led to a decline in overall tree growth rate, soil productivity, and forest health.

Tropical Rain Forest:
Tropical rain forests blanket the Earth like a wide green belt around the equator. They are common in Asia, Africa, South America, Central America, and on many of the Pacific Ocean islands. Tropical Rainforests maybe called the lowland equatorial evergreen rain forests. These forests incur heavy showers of 100-600cm a year, and hence the name, Rainforests. For this reason, the soil can be poor because high rainfall tends to leach out soluble nutrients. Wherever temperature is high enough and rainfall heavy and regular enough, there is rain forest. These forests experience an average temperature of about 80° F (26° C), with no pronounced cold or dry spells. Not only the quantity of life found in these forests, but also its diversity makes them so vital. Some of the strangest and most beautiful plants and animals are found in rain forests. They are home to two-thirds of all the living animal and plant species on the planet. It has been estimated that many hundreds of millions of new species of plants, insects, and microorganisms are still undiscovered and as yet unnamed by science. Tropical rain forests are called the "jewel of the earth", and the "world`s largest pharmacy" because of the large amount of natural medicines discovered there. Rainforests are dominated by the broad-leaved evergreen trees, which form a leafy canopy over the forest floor. Taller trees, called emergents, may rise above the canopy. The upper portion of the canopy often supports a rich flora of epiphytes, including orchids, bromeliads, mosses, and lichens, who live attached to the branches of trees. The undergrowth or understory in a rainforest is often restricted by the lack of sunlight at ground level, and generally consists of shade-tolerant shrubs, herbs, ferns, small trees, and large woody vines which climb into the trees to capture sunlight. The relatively sparse understory vegetation makes it possible for people and other animals to walk through the forest. Coffee, chocolate, bananas, mangoes, papayas, avocados and sugar cane all originally came from tropical rainforests, and are still mostly grown on plantations in regions that were formerly primary forest.

Just a few thousand years ago rain forests covered 14 percent of the Earth`s land surface, or 5 billion acres. Humans already have destroyed half of this forest area, with most damage occurring in the last 200 years. With just 2.5 million square miles (647 million hectares) of tropical rain forest remaining, we continue to lose an estimated 93,000 square miles (150,000 square km) a year. Rain forests are being eliminated for timber, minerals, agriculture, and human settlement.

Temperate Deciduous forests:
Deciduous forests are those, which consist of predominantly broad-leafed trees. Deciduous forests are of two types: temperate and tropical. Temperate deciduous forests occur in areas of moderate temperature and rainfall with cold winters. Species belonging to these forests drop leaves in autumn. The deciduous forests in tropical areas shed leaves only by December (in the Northern Hemisphere) when water becomes scarce. The tropical monsoon deciduous forests are found in areas receiving annual rainfall of 100 to 200 cms in India, with a distinct dry and rainy seasons and a small range of temperature.

The deciduous can further be divided into moist and dry. The moist deciduous forests are found throughout India except in the western and the northwestern regions. They occur on the wetter western side of the Deccan Plateau, the northeastern part of the Deccan Plateau and the lower slopes of the Himalayas, on the Siwalik Hills from Jammu in the west to West Bengal in the east. The trees have broad trunks, are tall and have branching trunks and roots to hold them firmly to the ground. Some of the taller trees shed their leaves in the dry season. There is a layer of shorter trees and evergreen shrubs in the undergrowth. These forests are dominated by sal and teak, along with mango, bamboo, and rosewood. The Dry deciduous forests are found throughout the northern part of the country except in the Northeast. It is also found in Madhya Pradesh, Gujarat, Andhra Pradesh, Karnataka, and Tamil Nadu. The canopy of the trees does not normally exceed 25 metres. The principal trees of these forests are teak, sal, sandalwood, mahua, khair, mango, jackfruit, wattle and bamboo, semal, sisasm, myrobalan, arjun and the banyan tree.

Usefulness of Forests:
Forests are unique and irreplaceable. Forests serve as home to many of the unknown species of mammals, wildlife, reptiles, insects, birds and so many others, which are yet to be named by scientists. More forest leads to more greenery around, leading to more rainfall and better crops. Deforestation is one of the major reason for an increase in global warming.

Mankind has come a long way from the old, primitive way of living in the forest and discovering fire! So much so, as to now the same mankind who thought forests to be his home, is up to destroy them, avoiding to know its importance.

Human beings and forests have always had a complex relationship. We have depended on forests as long as we have inhabited the planet - getting clean air to breathe, food and water from it, fuel, shade and shelter, and now we need it for economic gain as well.

Early humans were known to worship trees, and even today, in some parts of the world, forests are regarded as places of awe, with spirits attributed to be living there. The worship of forests, plants and animals, and appeasing of animal and tree spirits are still quite common in some cultures, and the forest is treated with the kind of respect reserved for divine objects. Old growth forests are important for industries other than logging, such as tourism, wildflower picking, fine woodcraft and beekeeping. These industries are more ecologically sustainable than logging or mining in old growth forest because they don`t disturb the natural life cycle of the ecosystems. We need more old growth forest put into national parks and nature reserves for the increasing numbers of people wanting to appreciate our unique natural heritage.

We have been taking continuously from the forest to feed the ever - growing need for wood, and wood and non - wood products, to provide land for the ever increasing population for housing and cultivation! Forests are the Earth`s largest and most productive ecosystem, and tree their most visible and important constituent.