Grade 11 Botany Note
About one third of the land surface is covered by the forest. According to the department of forest and natural resources survey 29% land is covered by forest. Protection, preservation and utilization of forest product are called forest conservation. Ecological studies have shown that the forest helps to maintain the level of rainfall. Forest is necessary to check the floods and soil erosion and are important for wild life, human recreation etc. the forest helps to maintain the gases.
Important of forest:
1. Forest occupies the central position in the nature which provide the wood, food, fodder and the raw material for various industry.
2. Habit and habitat for the wild animal.
3. Forest balance the various gaseous cycles in nature.
3. Water cycle maintain in nature.
4. Forest provides the medicinal plant, which are widely used.
5. Reduced the problem of global warming and green house, soil erosion.
Types of forest in Nepal
Altitude and climate, different types of forest is found in Nepal, they are
1. Tropical forest:
1000m from the sea level occupied by the tropical zone forest, extended from east to west. It is characterized by the abundant rainfall and high temperature, different kinds of deciduous trees dominated by the sal forest. The other tree species are Adina cordifolia(karma), Terminalia bellirica (barro), Acacia catechu (khair) is the most common. Reverine forest includes Alibizzia procera (siris), Bombax ceiba (simal), Cassia fistula (amaltus).
2. Sub-tropical forest:
This forest lies in between 1000-2100m. It is characterized by the moderately warm and humid climate. The trees mainly Schima wallichi, Castonopsis indica in the central and eastern region and in western region-Alnus nepalensis and Pinus
3. Temperate forest:
This lies in between 2100-3000m.this mainly characterized by the presence of laural, evergreen oak, mixed broad-leaved deciduous and Rhododendron forest in the eastern and the central region of Nepal, while in western –evergreen coniferous forest and deciduous forest.
4. Sub-alpine and alpine forest:
Sub-alpine lies in between 3000-4000m. And the alpine lies in between 4000-5000m, mountain country of Nepal comes under the Alpine zone. The climate is very cold, dry and windy. The sub-alpine region mainly consists of Betula utilis-Rhodendron companulatum at the upper region of sub- alpine near the timber line.
Alpine zone mainly consists of grasses, herbs, and dwarf shrubs. Some of the well-known ones are Juniperus spp. and Rhodondren spp.on exposed slopes.
Due to the rapid increase in the growth rate of population there is increase in the demand, to complete their demand they mainly depends on forest product. In Nepal rate of deforestation has been 2% per year. The major cause of deforestation is:
1. Over grazing:
Due to increase in population, there is also increase the livestock to sustain their life activity and their increase in problem, due to presence of only limited land area so to solve the problem they used the forest for grazing.
2. Road construction and industries:
Another major cause of deforestation is construction of road , building, other infrastructure. It affect the stability of hill slopes, damage the protective vegetation, block natural drainage causes the flood and landslide. Increasing the population they need their basic things and they construct the house and industries due to this over-exploitation occur.
3. Fuel wood collection and timber wood collection:
Over collection of tree for wood and timber for firing and to build the infrastructure causes the deforestation.
4. Forest fire:
Serious damage of fire has been observed in dry deciduous forest. Fire only the destroy the standing tree but also destroy the fallen leaves, organic leaves which causes the decrease in the content of humus.
Air pollution, acid rain causes the serious damage to forest vegetation through the world.
Hazards of deforestation:
1. It causes the irregular rainfall sometimes heavy rainfall.
2. It leads to soil erosion and landslide.
3. It leads into the imbalance in water cycle, gaseous cycle also increase the greenhouse effect and global warming
4. Increase in the flood, landslide.
Methods of forest conservation:
1. Conservation from over grazing:
2. Control of fuel wood and timber collection
3. Intensive plantation
4. Production\ capitative plantation:
5. Community forestry
6. Afforestation of wet land
7. National legislation