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.
Most people think that a tropical rainforest is the same as a ‘jungle’. This is not the case because a jungle is usually meant to describe an immature tropical rainforest. The word ‘jungle’ came from the Sanskrit term ‘jangala’ which was a description of a thick and impenetrable type of vegetation. This was however true based on the outer edges of the tropical rainforest and parts that are along the riverbanks. Observations into the deeper ends of a tropical rainforest indicate that the forest floor is uncluttered and open. Basing on this fact, then it will be wrong to conclude that a jungle means the same as a tropical rainforest.
Because tropical rainforest are known for their divergent vegetations, many people assume that the rainforest has a well drained and fertile soil which in real is not the case. Actually the opposite is true for this in that tropical rainforest does well in soils that are poor and not so deep in depth (around two or three inches towards the soil). The plants that grow in tropical rainforest have adapted themselves by spreading on a large area just below the surface of the soil. This enables the plants to be in a position to absorb water more easily from the environment and at the same time obtain mineral nutrients from the decaying plants and animal materials before they are leached into the soil. As a result of this, the plants in the tropical rainforest obtain a lot of nutrients compared to its environmental plants.
In order to cope up with the surrounding conditions, the tropical rainforest leaves have adapted themselves dutifully to climatic conditions in the tropical rainforest. The tall trees that have access to strong winds, low level of humidity and high temperatures, have their leaves so small in size. The small size of leaves cuts down the surface area when they are exposed to the harsh conditions of high temperatures and strong winds. Most of these plants that have small leaves are almost closely adapted to desert conditions. Down the layer into the canopy layer, the leaves become broader because there is lack of strong winds except for the increased temperatures and high humidity level. The road leaves enables the plants to absorb the maximum amount of light they get access to and use it to carry out the photosynthesis process.
Many of these plants in the tropical rainforest have dropping leaves which enables the plant to release excess water more efficiently. Some other plants have leaves with holes to prevent accumulation of water in the leaves. Another feature that is observed in the tropical rainforest plants is that the tall trees in the canopy layer have shallow root systems which give them support. Schneider and Root, (pp 712) indicated that the trees developed other root systems to increase stability in the ground. These trees developed buttress, aerial and stilt roots as a result. An example of a tree that developed buttress roots is the ‘kapok tree’. The tree root grew to a considerable height above the ground, sometimes 6.0 – 9.3 meters up the trunk. Stilt type of roots is seen in stilt palm and mangrove trees which grow in the wet and marshy region. They protrude from the trunks of trees above the ground and are at times called the ‘prop roots’. Aerial roots are seen in banyan tree which when growing spreads to greater distances. These roots grow from the branches and gives support away from the main trunk of the tree.
Tropical rainforest contains a large number of plants that grow on other plants without establishing contact with the ground or the floor of the forest. Such plants are referred to as ‘epiphytes’ and they obtain there nutrients from the air. They support themselves to the other plants in order to obtain sunlight from above the tall trees but they do not depend on them for nutrients (Osterndort et al, 2001). Examples of the known epiphytes include the orchids, mosses, bromeliads and ferns and have beautiful flowers.
Tropical rainforests plants have developed mechanisms that protect themselves from other plants and animals and as a survival strategy in the forest. Some of the plants have developed thorns and spines to keep away animals that may be tempted to climb on them. Some have smooth trunks and even shed their barks to prevent attachment of the epiphytes such as the fern or the vines. The plants that have holes in them prevent further attacks from the insects because it gives the impression that other insects have already eaten some parts of it or they are still in the process of eating it.
Scientists have estimated that there is over 40 000 plant species that are yet to be discovered in the tropical rainforest vegetation more especially in the Amazon basin. They have already identified over 300 species of plants in the Peruvian Amazon only. It is believed that the tropical rainforest has 50% to almost 80% of plants and animal species making it to be the most biologically diverse ecosystem on earth.
Morecroft and Keith (pp 300) discovered that much of what we use and eat today comes from the tropical rainforest and this includes food, spices, resins, oils, hardwood, canes and fibers. These are examples of things that we have come to depend on. Also evident is the fact that almost 30% of modern drugs are derived from compounds in plants that are obtained from the tropical rainforest. Heart medications, cancerous drugs, painkillers, anesthetics and relaxer drugs are just some of the drugs obtained from these forests.
It has been observed that the tropical rainforest trees receive more than 63 inches of rainfall yearly and this climate favors the growth of trees and plants in the tropical rainforest. Through the process of transpiration and evaporation, the trees in the tropical rainforest returns almost 80% of the rain water back to the surrounding therefore benefitting those living in the surrounding area. The plants also control the flow of water in the environment thus preventing occurrence of a flood or erosion (by wind or water). The existence of tropical rainforest also aid to prevent spread of diseases in that it controls the populations of disease causing insects and plants.
It has been observed that the most driving force to tropical rainforest destruction is the act of cutting trees for commercial or industrial use. Tropical hardwoods such as rosewood, teak and mahogany provide wood products that are great for timber production, charcoal, building and also exported to different countries. The slash and burn operations of tropical hardwoods have created deficiency of the trees in some countries which initially used to export the trees (Morecroft and Keith, 2009). Currently, Japan is the largest importer of the tropical hardwoods but it has been anticipated that countries such as Ivory Coast, Nigeria and Philippines may follow suit if they continue exporting the trees in the next five years.
In addition to logging of tropical trees for export, much of it is consumed locally by the individual countries such as the steel industry in Brazil. The steel industry that produces steel for making cars in Japan uses tons of wood to produce charcoal that can be used in the production process. Another consumer of the tropical rainforest trees is the paper industry that consumes over 4 billion tons of wood yearly to be able to meet the demands of customers. Most of the times when the timber is harvested, trees, plants and animals that have lived for long periods in the canopy layer and have become adapted to the environment, find it hard it hard to adapt themselves to an open environment of sunlight and therefore shifts or becomes extinct with time.
The demands for meat in the western regions, especially in Brazil, have contributed to destruction of rainforests to provide grazing land for animals. Most of the Latin and central rainforests have been lost due to cattle business in quest to satisfy the demand of consumers in the regions and other countries. The cattle operations have continued to move southwards towards the South America’s rainforests and it is estimated that the spread will continue further to some parts of Eastern America Rainforests.
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.
From the above observations made it is clear and evident that the tropical rainforest is one of the largest plant vegetation that has to be taken care of by those interacting with it. It has been established that the tropical rainforest woods may face extinction in the years to come because of the various operations that take place in the forest. Some of the identified operations include slash and burn for timber, cutting down the trees to provide land for grazing and use of timber for paper industry. The climate in the region has favored the growth of different species of plants which have been observed to contain useful compounds for making drugs and modern medicines.
Conclusively, it has also 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.
Work Cited List
Isaac, J. L and Williams, S. E “Climate Change and Extinctions” Encyclopedia of Biodiversity, 2007: 1-7. Print
Lewis S.L. “Tropical forests and the changing earth system.” Phil Trans R Soc B. 361, (2006): 195-210. Print
Malhi, Y and Phillips, O.L“Tropical forests and atmospheric carbon dioxide”. Trends in Ecology Evolution Journal 15, (2000): 332-337. Print
Martinelli, L., Moraes, J. , Ballester, M. V, Krushche, A. , Pellegrino, G. , Almeida, R and & Richey, J . “Surface air temperature variations in the Amazon region and its border during this century. “ Journal of Climate 1, 2008 : 1105-1110.Print
Morecroft, M. D and Keith, S. A “plant ecology as an indication of climate and global change.” Journal of Climate Change, 2009: 297-305. Print
Osterndorf, B, Hilbert D.W, and Hopkins M.S “The effect of climate change on tropical rainforest vegetation pattern.” Journal of Ecological Modelling 145, (2001): 211-224. print
Schneider, S. H and Root, T. L“Climate Change and Ecology, Synergism of.” Encyclopedia of Biodiversity, 2007: 709-725.Print