ecology forest
TRANSCRIPT
ECOLOGY :
PART 1 – FORESTS
Ecology
(from Greek: οἶκος, "house", or "environment"; -λογία,
"study of" [A]) is the scientific analysis and study of
interactions among organisms and their environment. It
is an interdisciplinary field that includes biology,
geography and Earth science.
Flora (forests) and fauna(animals) are one of the renewable resources of
our country. The flora of India is diverse. It is estimated that our country
possesses 45,000 different species of plants. This is the widest range of
diverse plants found in any country in the world. Nearly 5000 species are
found exclusively in India. We can subdivide the forests of India into five
classes. They are:
1. Tropical Rain Forests (Ever green forests)
2. Tropical Deciduous Forests
3. Thorn and Scrub Forests
4. Tidal Forests (Mangrove Forests)
5. Mountain Forests
Forest in india
Distribution of forest cover
1. Tropical Rainforests (Ever Green Forests):
These forests grow in areas having a rainfall of more than 200 cms.
These are found in the mountain ranges of North-eastern India, in
the western slopes of the Western Ghats, along the foot-hills of the
Himalayas and in the Andaman and Nicobar Islands. The trees of
these forests don’t shed their leaves in any season of the year. They
always looks green. So they are called ‘Evergreen Forests’. Trees
like Ablus, Mahogany, ebony, rosewood, sisham (Dalbergia Sissoo),
Sandalwood (Santalum album) grow in these forests. The trees are
tall and form a dense canopy overhead. Trees of these forests
reaches up to a height of 60 meters or even more.
2. Tropical Deciduous Forests: • Deciduous forests are called Monsoon Forests. This is because they form
the natural cover almost all over India particularly between regions of 200
and 75 cms of rainfall. This forest- cover accounts for more than half of
the total forest area of India. They are very Important from economic point
of view.
•They are called ‘deciduous forests’ because the trees of these forests
shed their leaves in the dry season of the year.
•Trees like Teak (Tectona gradis), Sal(Shorea rabusta), Sandalwood
(Santalum album), Shisham (Dalbergia sissoo), Hurra (Terminalia chebula),
Khair(Acacia catechu), Bamboo and Cane grow in these forests.
•These forests are confined to north-eastern India, eastern slopes of the
Western Ghats, the Eastern Ghats, Chhotnagpur Plateau, Orissa,
Chhatisgarh and Madhya Pradesh.
3. THE THORN AND SCRUB FORESTS:
These are confined to areas with a rainfall of less than 75cms. It spreads over
north-western part of the country from Saurashtra in the south to Punjab plains in
the north.
It is found in parts of Rajasthan, Punjab, Uttar Pradesh, Madhya Pradesh, Haryana
and also in parts of south India. Kikar, babul, khair, acacia, munj and sawai grass
are found in these forests. These forest areas are being converted into residential
areas due to population pressure. Thorn and cactus are found in western Punjab
and western Rajasthan where the rainfall is less than 50 cms.
4. TIDAL FORESTS:
The tidal areas along the coast of India particularly the lowlands and river-mouths
of the eastern coast is covered with mangrove forests. Mangrove trees can
survive both in fresh and saline water- the major characteristic of the tidal areas.
Sundari is a well-known mangrove tree. It is after the name of this tree that the
name sundarban has been given to the vast tidal mangrove forests of the Ganga-
Brahmaputra delta in West Bengal. Due to the abundance of Hental trees, the
mangrove forests of the Mahanadi-Brahmani mouth are called ‘Hentalban’. It is
also called ‘The Little Sundarbans’.
5. MOUNTAIN FORESTS (ALTITUDINAL ZONES OF VEGETATION IN
MOUNTAINOUS REGIONS OF INDIA):
•Altitude is an important factor in the distribution of vegetation in the
mountainous regions because of the decrease of temperature with the increase
of altitude.
•The Himalayas are covered with all types of vegetation starting with tropical
rain forests in the foothills to tundra vegetation on the peaks. Due to the hot
and humid climate, siwaliks, the foothills of the Himalayas are covered with
tropical rain forests and moist deciduous flora. Sal is the most important and
dominant species. It is then succeeded by wet hill forest between 1000 and
2000 meters. Evergreen broad leave oaks, chestnuts and apple trees are
common trees in these altitudes.
•Further up between 1600 and 3300 meters above sea level, pine, cedar,
spruce and silver fir are found which are some of the most important species in
these altitudes. These forests are the coniferous forests of the temperate
regions of the world found in these altitudes of the Himalayas.
• Temperate coniferous forests is succeeded by Alpine Forests which is found
generally at altitudes between 2750 to 3600 meters above sea level. These
forests are covered with species like silver firs, pines, birches and junipers.
Above 3600 meters above sea level, Alpine Forests give way to Alpine
Grasslands. The peaks of the Himalayas are covered with perpetual snow.