KEY PROCESSES

Figure 6.0 Showing some of the key processes which occur in the Tropical Rainforest

The soil of the tropical rainforest is described as being thin, infertile, poor, and nutrient deficient. This is attributed to the vast amount of rainfall that quickly washes away the nutrients from the soil. In some instances, trees have the ability to absorb the nutrients from the soil before it is washed away.

However, the rain results in leaching of the soil and the depletion of the nutrients that are essential for activities of plants.

Tropical rainforests are teeming with

diversity in all aspects. These ecosystems are essential in the regulation of the Earth’s climate and biochemical cycles which are done through the exchange of energy, water, and nutrients within the atmosphere. As the name suggests, the tropical rainfall experiences high percentages of precipitation annually. Rainfall in this ecosystem provides dual effects in the form of benefits and disadvantages to both biotic and abiotic counterparts. Even though rainfall evokes negative effects, it is equally as important as the positive attributes as it is the rainfall that spearheads many of the ecological processes that occur due to interactions between the various organisms, the environment, and the atmosphere. Ecological processes, whether they be physical or biochemical, are the driving forces behind the sustenance and maintenance of the tropical rainforest

ecosystem.

Figure 6.1 Showing the soil profile of the Tropical Rainforest

Figure 6.2 Showing Fungi seen on forest floor

KEY PROCESSES

DECOMPOSITION

How then does the tropical rainforest maintain its lush, picturesque beauty and carry out its functions? The negative effects of rainfall in the ecosystem are counteracted by the successive, quick, and constant turnover of nutrients in the various nutrient cycles. Nutrient cycles are extremely rapid due to the humid conditions that allow the decomposition of matter to occur at an accelerated speed.

When vegetation die, whether it be trees, shrubs, or the leaves of plants, and descend to the forest floor, decomposers and detritovores begin their work of breaking down the substances into organic matter. Trees that may have toppled over as a result of natural phenomena are also broken down.

THE NITROGEN CYCLE

This process is involved in the cycling of nitrogen which results in the production of organic nitrogen and ammonia. Bacteria, fungi, termites, and other insects are just a few key players in the process of decomposition and the nitrogen cycle. The faeces from animals present within the tropical rainforest adds nutrients to the soil as well.

Figure 6.3Showing the settling of the mist in the forest

KEY PROCESSES

Figure 6.4 Showing the Heliconia rostrata, commonly known as the Balisier

B

Beneficiaries of the decomposed organic matter and the animal droppings include trees, which take the nutrients in their roots through osmotic processes, epiphytes or “air plants”, worms’ millipedes and beetles. Once eaten, the nitrogen cycle moves into the phase of assimilation as the consumed nitrogen by these organisms is utilized for growth and replication.

THE WATER CYCLE

The positive attributes of rain in the Tropical rainforest can be demonstrated in the hydrologic cycle and photosynthesis which works in conjunction with the carbon cycle. The hydrologic cycle is described as the movement of water between the earth and the atmosphere. As the sun’s rays reach the plants of the ecosystem, its light is not only absorbed for the process of photosynthesis, but it aids in the evaporation of water from water reservoirs and the surface of the leaves in a process known as transpiration. Once the water vapor is in the atmosphere, it cools and condenses to form clouds. When the clouds become heavy, precipitation occurs, and water is returned to the earth. Infiltration occurs as water moves into the soil. The rainwater travels down the slope of the mountains where it is collected by rivers. The water does not stay there, but it flows through the valleys that are found in the Vermont Rainforest in St. Vincent and then runs off into the sea.

PHOTOSYNTHESIS

Water is also used in the process of photosynthesis. The carbon cycle and photosynthesis are two process that work hand in hand. Because of the low water potential of the roots, water moves via the process of osmosis from the soil and into the plants. The plants then absorb carbon dioxide from the atmosphere. The pigments that are present in plants whether primary or accessory allow the plant to absorb different wavelengths of light. These reactants, carbon dioxide and water, in the presence of an energy source, which is sunlight, produce glucose and a byproduct of oxygen. This process, known as photosynthesis, is the process by which plants make their own food.

THE FLOW OF ENERGY

Photosynthetic energy is passed through the ecosystems through food chains, food webs and energy pyramids. A food chain shows the flow of energy between organisms within an ecosystem. A food web is described as an interconnection between food chains. An energy pyramid not only shows the flow of energy between organisms, they allow one to see the various trophic levels in the ecosystems and the energy lost as one moves higher up on the pyramid. These structures are inclusive producers, which are found on the first trophic level of producers and consumers, otherwise referred to as autotrophs and heterotrophs. Autotrophs have the ability to make their own food whereas heterotrophs obtain their food sources by eating other plants and animals in the ecosystem. Heterotrophs contain subclasses which are herbivores carnivores and omnivores. Herbivores, first order heterotrophs, are plant eating organisms. Carnivores, can be second order or third order heterotrophs, depending on whether the animal they consume is an herbivore or a carnivore, respectively.