Tropical Climate And Evergreen Forest
The tropical climate is also known as rainforest climate or the equatorial climate. This type of climate has similar weather conditions throughout the year. The region is also a high energy region as it receives maximum insolation from the sun which explains its rich flora and fauna.
Tropical Climate And Evergreen Forest
Regions, where the tropical climate is found, are dominated by equatorial rainforests or the evergreen rainforests. They are broad-leaf forests which are a type of evergreen forests found on lowlands.
- This type of climate is found close to the Equator, usually within 5 to 10 degrees to the North and South respectively.
- This region is also known as the Equatorial doldrums.
- It is found across three continents - South America (Brazil, Bolivia, Colombia, Equador, Guyana, Peru, Suriname, and Venezuela), Africa (Congo, Burundi, Rwanda, Central African Republic etc.), Asia (Indonesia, Malaysia, Laos, Cambodia, Thailand etc.)
- The region experiences uniform temperatures throughout the year.
- The sun shines vertically over this region for most of the year. Hence the region doesn't experience any definite winter season.
- However, the daily temperatures do not cross 32 degrees centigrade even in the afternoons due to heavy precipitation which moderates the temperature.
- The average daily temperature is around 27 degrees centigrade for almost all the months in the year. There is very little annual variation in the mean temperature.
- The diurnal range is low too, with night temperatures not falling below 20 degrees centigrade.
- The diurnal range is greater than the annual range of temperature
- This region experiences very high precipitation throughout the year.
- There is no distinct dry season since rainfall occurs in all the months of the year.
- While the average annual precipitation is over 150 cm, some regions experience very high precipitation in the range of 250-300 cm.
- Rainfall peaks in the months of April and October (months following the equinoxes). Lowest rainfall occurs in the months of June and December, due to solstices.
- Continuous evaporation of seawater and the land and sea breezes are the reasons for such high levels of precipitation.
- Convectional air currents are responsible for the formation of thunderstorms in the afternoons, resulting in heavy downpours.
- Equatorial rainforests are the typical vegetation type found in this region.
- The region is characterized by broad-leaf trees with a tall and dense canopy.
- The canopy is so dense that very little sunlight reaches the surface of equatorial forests.
- Because of abundant sunlight and precipitation, the growing season exists all around the year. There is no distinct drying season where the trees shed leaves. Shedding and blooming of leaves and fruits occur throughout the year.
- The vegetation exists in layers with the bottom-most layer comprising of decaying organic matter, which is slow to decompose due to low sunlight. A very dense layer of canopy exists with trees growing as tall as 90 feet - this layers most of the wildlife of these forests. Above this lies the emergent layer of crowns of a few trees which protrude out of the dense canopy. This layer receives maximum sunlight and also has to endure strong winds.
- On the thick trunks of many of the trees, there is a layer of climbers known as the lianas. Epiphytes are small plants which grow on the trunks and branches of these broad-leaf trees.
- The rainforests of Amazon are known as Selvas (forests with a dense canopy)
- The trees of the hardwood variety. Prominent hardwood varieties include - Mahogany, Ebony, dyewoods etc.
- Apart from the dense hardwood forests, mangrove vegetation is also found in the swamps and coastal regions.
- Since the region is covered with dense vegetation, development of infrastructure networks for robust connectivity and efficient movement of goods is hampered.
- The variety of economic activities taken up in this region is hence limited.
- The region does not have adequate plain, grassland topography which can be used for crop cultivation. Hence the most common type of cultivation that is practised in this region is the shifting cultivation.
- Also known as the slash and burn cultivation, this involves cutting down and burning a piece of forest land on which crops are cultivated for 2-3 years, before shifting to a new piece of land.
- This type of cultivation is common with the indigenous inhabitants of rainforests - mainly the tribals. This is also practised in the rainforests of Andaman and Nicobar islands.
- Bananas, maize, tapioca, and groundnut are the plants cultivated under this practice of shifting cultivation.
- Apart from this, a primitive form of hunting-gathering is also practised due to the abundance of food resources.
- Plantations were introduced in this region by Europeans, especially in the Indonesian islands of Java, Sumatra, Malaysia, Equatorial West Africa, and Central America.
- Plantation crops require abundant sunshine and adequate precipitation throughout the year. Hence the equatorial rainforests are cleared to make space for plantation crops as the region offers suitable conditions for the cultivation of plantation crops.
- Brazil, Indonesia, and Malaysia were the leading producers of natural rubber. However, Brazil is no longer a leading exporter of natural rubber.
- Cocoa is cultivated in equatorial Africa, mainly in Ghana and Nigeria. This forms an important ingredient in the making of chocolate in Western countries.
- Indonesia and Malaysia have emerged as the leading producers of oil palm.
- Apart from the above, tea, tobacco, coconut, sugar, spices etc., are the important plantation crops cultivated in the equatorial region
- Extension of plantations has led to the clearing of almost half the rainforests in this region.
Important characteristics of equatorial regions
- Communicable diseases such as Malaria, Yellow Fever etc., are still widely prevalent in these regions because of high temperatures and humidity which favour the growth of disease spreading vectors such as mosquitoes and flies.
- Insects and pests also affect crop cultivation, apart from humans and cattle.
- Soils in this region are heavily leached due to intense rainfall washing away the major nutrients. Heavy downpours also result in soil erosion, washing out the topsoil. Hence it is difficult for forests to regrow in this region once they are cleared. It usually takes several decades for the soil to replenish its nutrients, to create favourable conditions for the growth of trees.
- This region is rich in mineral resources. Gold mining in Peru, oil and gas extraction in Indonesia, copper mining in Papua New Guinea, rare earth mining in Congo are the prominent examples. Mining is another reason for the rapid destruction of the rainforest ecosystem.