Tropical rainforests are located some distance around the equator and it is one of the earth’s spectacular wonders. It runs from the tropic of cancer in the northern side of the equator to tropic of Capricorn in the southern part of the equator. Examples of largest known tropical rainforests are found in Brazil (South America), South East Asia, Indonesia (islands near the Indian Ocean), and Democratic Republic of Congo (Africa), and in the Caribbean Islands (Isaac and William, 2007). The largest tropical rainforest is the Amazon rainforest found in the South America and which covers almost two thirds of the United States continent (Malhi and Philips, 2000). Tropical rainforests are defined by their wet climate condition in that it receives 400 to 760 cm of rainfall each year as observed by Morecroft and Keith (pp 298). The climate consists of uninterrupted warm temperatures, high humidity and high rainfalls. Its temperatures range between 25 to 30 Degrees Celsius. This paper will look at the climate that exists in the tropical rainforest and how it affects the growth of a variety of plants in the tropical rainforest.
The tropical rainforests made is made up of mostly wet seasons and its climatologic regions lie within the inter-tropical convergence zone. The different types of rainforests are categorized according to the different types of weathers they experience during the year and considering their geographical location (Osterndort et al, 2001). These rainforests includes the monsoon, subtropical and the equatorial type. The rain is experienced almost every day and it lies between 1500 to 2500mm throughout the year. The temperatures vary during the day and night in that during the day, the temperatures range between 30 to 35 degrees Celsius while during the night, the temperature drops to between 19 and 24 degrees Celsius. The type of climate experienced in the tropical rainforest is the equatorial climate and it is characterized by high relative humidity ranging from 77% to 88% and this supports a variety of plant species (Martinelli et al, pp 1107).
The tropical rainforest is filled with green vegetables throughout the seasons because of the high rate of rainfall which encourages growth of trees that form canopies which provide shade to other plants and animals living in the area. The atmosphere is always humid, hot and damp due to the canopies that are formed from the trees. The rainforest provides a home to different types of animals and contains many species of plants more than any other type of vegetation areas known. Its climate has no pronounced summer and winter in that the temperature differences between the day and night is observed to be larger than the differences in temperature between summer and winter.
The climatic characteristics that defines the tropical rainforest includes average daily temperature of around 27 degrees Celsius, the diurnal temperature change is between 2 and 5 degrees Celsius, the latitude comes under the doldrums low pressure belt all the year round, the rainfall is usually convection al and finally the midday sun is always near the vertical and is overhead twice a year at the equinoxes. The rainforest soils are not usually fertile and this is because the continuous rains wash away the valuable nutrients. The daily weather cycle of the tropical rainforest begins in the morning when the sun shines, heats up the ground making hot and wet air rise in the atmosphere then in the afternoon, the dark clouds brings the rain and thunderstorms in the rainforest and this cycle is repeated continuously each day resulting to an ever wet area (Lewis, 2006).
The rainforest is made up four layers namely; the emergent layer, the canopy, the understory and lastly the plants that make up the forest floors. Firstly, the emergent layer consists of a small number of trees that are tall which is referred to as ‘Emergents’. The trees grow above the canopy that is has been created by the other trees and reaches to a height of about 54m. These trees are adapted to withstand strong winds and high temperatures from the direct sunlight. It is usually in habited by eagles, monkeys, bats and some butterflies.
Secondly, we have the canopy layer which also consists of tall trees of height 45m maximally. The canopy is estimated to contain an almost 50% of different plant species as it has been discovered to be the densest area of biodiversity. It contains epiphytic plants which attach themselves to tree trunks and branches for support. These plants also obtain water and mineral salts from rain and debris that is collected from the other supporting plants in the canopy region (Schneider and Root, pp 710).
Thirdly, we have the understory layer which is located in the region between the forest floor and the canopy. These area forms a habitat to snakes, lizards, leopards, boa constrictors, birds and other predators. The region does not receive enough sunlight due to the canopy layer above it in that approximately, the under story receives 5% of total sunlight. It is sometimes referred to as a shrub layer’. The last layer is the forest floor which is estimated to receive only 2% of sunlight. The area is characterized by low vegetations because of the relatively low sunlight penetration and only plants that are adapted to low light survive in this region. The rate of decay in plants and animal matter are sped up by the availability of warm and humid conditions. The presence of fungi also speeds up the rate of decay of plants and animals.
For many years it was thought that plants in the tropical rainforest were unaffected by the equatorial climate but recent studies indicated that the warm temperatures of tropical rainforest affected the growth of a variety of plants in the region. Lewis (pp 198), stated that the drier conditions in the cloud forest could lead to extinction of some species of plants more especially the orchids. He also monitored tree growth, tropical temperatures and level of carbon dioxide released as a result of high humidity and warm climate. His researches on the matter revealed that the tropical rainforest trees gave off more carbon dioxide than they could use and this resulted to a change in the composition of forest. He also noted that the trees at times grew at a slower rate when the nights were warm. Other studies by Osterndort et al (2001) indicated that some trees grew at a faster rate when the level of carbon dioxide rose while other tree types declined in vitality.
Lewis (pp 200), indicated that an increase of carbon dioxide in the tropical rainforest was the main reason for the abrupt shifts in species growth and this, he noted, could lead to serious ecological repercussions in the area experiencing these.
The type of climate experienced in the tropical rainforest has made plants growing in the area to adapt themselves so that they can survive the existing conditions such as growth of bushes and canopies. Examples of such plants and how they have adapted themselves includes; lianas which have thick vines that loops around the trunk of trees to reach the top and receive sunlight. Usually their stems come in different shapes and varying length. Their life begins from the forest floor but they grow upwards depending on trees for support until they reach to the top of the tall trees. When they reach at the top, they then spread towards other lianas and trees and wound themselves tightly so that they can be in a position to resists strong winds.
Another type of plant in found in the warm environment of tropical rainforest is the fern. The ferns grow in the forest floor as they are well adapted to survive on such a condition. Apart from these, we also have the epiphytes or air plants which perch themselves high on the branches as they become detached from the ground. They begin their life from the canopy from seeds taken there by wind or birds. Some of the tallest trees have buttress roots system which ensures total stability against strong wind and to increase the surface area under which they obtain their nutrients from (Morecroft and Keith, 2009).
The diversity in plant species is said to be highest in the tropical rainforest region and it is the responsibility of individuals to ensure that the trees are maintained to allow growth of these trees. Tropical rainforest is reported to maintain a clear environment that is safe for human stay in that it uses up all the carbon dioxide in the air and releases a clean atmosphere.
Conclusively, it has been observed from the above that the equatorial climate in the tropical rainforest favors the growth of a variety of plant species. It is noted that the tropical rainforest is the largest ecological area that supports and gives a habitat to a diversity if plants and animals. The climatic changes have been observed by Malhi and Philips (2000), to be unchanging and are characterized by high levels of rainfall and high humidity. The climatic condition has created the emergence of different layers which contains a variety of plant species making it one of the earth’s most spectacular scenery