Tropical equatorial rainforests (TER) are located in a band 5-10 degree north & south of the equator (Zero degrees latitude), mostly in the area between the Tropic of Cancer (23.5° N latitude) and the Tropic of Capricorn (23.5° S latitude). This 3,000 mile (4800 km) wide band is called the "tropics."
Fifty seven percent of all tropical rainforests are found in Latin America. One third of the world's tropical rainforests are in Brazil. Other tropical rainforests are located in Southeast Asia and the Pacific Islands (25% of the world's tropical rainforests) and West Africa (18%).
Rainforests now cover less than 6% of Earth's land surface. Scientists estimate that more than 50% of all the world's plant and animal species live in tropical rain forests. Tropical rainforests produce 40% of Earth's oxygen.
Hot and wet describes the tropical rainforest climate. The average daily temperature is around 28ºC with an exception of cool nights (> 22ºC). Participation varies widely from a low of about 250cm/year to about 450 cm/year. The humidity of a tropical rainforest is usually 85%. There are no seasons in the rainforest, and the weather is basically the same thing everyday. It's hot, humid and rainy. It seems as if it's always summer because of this. To summarise:
The most important climate control in regard to the tropical climate types relates to the position of the Inter Tropical Convergent Zone (ITCZ). The ITCZ is an area of low pressure and marks the point of trade wind convergence. The reason for TER climate is due to a feedback between low pressure convectional processes that result from the high altitude of the sun (ITCZ) and the high levels of soil moisture and interception of rainfall from the dense vegetation cover leading to transpiration. This feedback leads to a repetitive climate pattern of hot humid air, dry but misty mornings and late afternoon downpours and convectional storms.
The influence of land and sea also has a critical affect on the migration of the ITCZ. Due to the heat retention and stability of temperature within the ocean the ITCZ remains more anchored to one position over oceans. In contrast land temperature vary over the year and temperature is also influenced by altitude and relief. These factors create greater ITCZ migration and climatic variation north and south over continents.
The nature of a forest in terms of its ecology is due to the amount of energy from the sun that reaches plants and animals. Several vertical layers are found in tropical rainforests, with distinctive plant and animal species. The following table lists the characteristics and vegetation for each layer.
The tallest trees are the emergents, towering 40-76m above the ground with trunks up to 5m around. Most of these trees are broad-leaved, hardwood evergreens. The plants that are common in this strata are Terminalia oblonga, Hymenolobium mesoamericanum, and Lecythis ampla. Animals found are eagles, monkeys, bats and butterflies.
The broad crowns of trees in this layer form a continuous, tight, 30-45m high canopy. 90% of the organisms can be found here, most of them seeking the treetops for brighter light. The branches of these trees are usually entangled with liana vines and covered with epiphytes. Many animals such as snakes, toucans and treefrogs live here since food is abundant.
Only 5% of the sunlight on the canopy reaches this area so the plants have to grow larger leaves to reach the sunlight. They seldom grow to 3.5m. It is comparatively an open space containing leafy herbaceous plants and young trees that can tolerate less amount of light. Animals include jaguars, red-eyed tree frogs and leopards. There is a large concentration of insects here.
This layer gets less than 2% of the sunlight, hence is mostly devoid of vegetation apart from plants that are adapted to very low amounts of light. It is covered with a thin layer of branches, leaves, fruits, and seeds, which decompose very quickly. It teems with animal life, particularly insects. The growth of fungi in this layers helps in the decay of the dead flora and fauna present. Giant anteaters live in this layer.
The vegetation in the tropical rainforest has evolved characteristics which help it to survive in the hot, humid and wet environment. Rainforest plants have adaptations that enable them to shed water efficiently. They also have adaptations to take in what little sunlight is available on the dark forest floor. Large leaves are common; they increase the amount of sunlight a plant can capture.
Listed are some common adaptations in tropical rainforest:
With warm temperatures, water and an abundance of food, tropical rain forests support thousands of wildlife species. The competition means organisms must adapt or develop specialized traits to compete for environmental resources. Many rain forest animals use adaptations to carve out their own niches and protect themselves from predators.
Tropical rainforests are among the most threatened ecosystems globally due to large-scale fragmentation as a result of human activity. Major human activities in tropical rainforest can be summarised as:
Slash and Burn
Most clearances are still by the local people and tribes needing land on which to grow crops. They clear the forest by ‘slash and burn’. Vegetation is cut down and then burned. The ash acts like a fertiliser adder nutrients to the soil. When the soil begins to turn infertile (usually after 3-5 years) the people move on. This is called shifting cultivation. It is a sustainable method of farming in the rainforest. It ensures the forest will recover.
To support the development of rainforest for other uses. The Transamazon Highway has allowed increased access to the Amazon Rainforest.
Commercial logging is the major cause of primary rainforest destruction in South East Asia and Africa. Worldwide, it is responsible for the destruction of 5 million ha. per year. Logging roads enable landless people to enter the forest. In Africa, 75% of land being cleared by peasant farmers is land that has been previously logged.
Ranching is a major cause of deforestation, particularly in Central and South America. In Central America, two-thirds of lowland tropical forests have been turned into pasture since 1950.
An unlimited supply of water and ideal river conditions have led to the development of hydro electric power stations (HEP Stations).
A significant amount of rain forest area has been damaged by agricultural practices. Large areas of a rain forest are completely cleared so the land can be used for cattle grazing, food crops and tree plantations. Because of deforestation the soil doesn't stay fertile for longer than a few years. Farmers are forced to destroy more rain forest areas and move on to new soil for their crops.
The mining of iron ore, bauxite , gold, oil and other minerals have benefited many LEDCs. However, it has also devastated large areas of rainforest e.g. Amazon.
The relocation to reflect the the rapid population increase if other areas cannot support their population.
Hunting and Poaching
The overhunting and poaching of animals can cause irreversible damage to the rain forest's ecosystem. When one species of animal becomes extinct, many other species cannot survive without it. In some areas of the world, animals have become endangered due to too much hunting by humans.
( Animation shows deforestation of the Amazon Rainforest in the western Brazilian state of Rondônia from 1986 to 2010)
Deforestation is the biggest threat to tropical rainforests. There are many reasons why forests are being cut down which include: small scale farming, commercial logging, cattle farming and commercial agriculture. Deforestation can have dramatic social, environmental and economic impacts.
The following diagram illustrates the impact of human activity in TER. Click the pdf file link below to view the diagram in full scale.
Rainforests used to cover 14% of the Earth, and now we only have 6% left. Every second, a section the size of a football field is cut down. An estimated 18 million acres (7.3 million hectares) of forest — roughly the size of Panama — are lost each year, according to the United Nations' Food and Agriculture Organization (FAO). Scientists estimate that in about 40 years, the 6% will be gone as well.
Some other statistics:
Deforestation is considered to be one of the contributing factors to global climate change. Trees absorb greenhouse gases and carbon emissions. They produce oxygen and perpetuate the water cycle by releasing water vapor into the atmosphere. Without trees, forest lands can quickly become barren land.
Using the following interactive timelapse by Google Earth to view the deforestation in Amazon rainforest 1984-1912.
Effects of deforestation
Forests are complex ecosystems that are important to the carbon and water cycles that sustain life on earth. When they are degraded, it can set off a devastating chain of events both locally and around the world.
Loss of Species: 70% of the world’s plants and animals live in forests and are losing their habitats to deforestation. Loss of habitat can lead to species extinction. This is not only a biodiversity tragedy but also has negative consequences for medicinal research and local populations who rely on the animals and plants in the forests for hunting and medicine.
Carbon Emissions: Healthy forests help absorb greenhouse gasses and carbon emissions that are caused by human civilization and contribute to global climate change. Without trees, more carbon and greenhouse gasses enter the atmosphere.
Water Cycle: Trees play an important part in the water cycle, grounding the water in their roots and releasing it into the atmosphere. In the Amazon, more than half the water in the ecosystem is held within the plants. Without the plants, the climate may become dryer.
Soil Erosion Without tree roots to anchor the soil and with increased exposure to sun, the soil can dry out, leading to problems like increased flooding and inability to farm.
Life Quality: Soil erosion can also lead to silt entering the lakes, streams, and other water sources. This can decrease local water quality, contributing to poor health in the local population.
As a response to climate change the United Nations and World Bank are proposing REDD (Reduced Emissions from Deforestation and Degradation) which will give money to developing countries based on how many carbon emissions have been avoided by not cutting down trees. The video concludes REDD does not address the causes of deforestation and that for this to happen the global north must reduce its consumption of meat, food, fuel and fibre.
Any solution to deforestation that does not respect the rights of local peoples is both unjust and ineffective!
The world has lost close to half of its forests already today, and the continued high pace of deforestation contributes greatly to climate change and the loss of biodiversity.
The following is the new Google Earth file presents a geographical account of global deforestation.It provides deforestation data from a number of sources for individual countries, including a live ticker for each country. Country profiles are also included as pops ups. Explore the interactive map to find out the forest and deforestation facts for different countries. Click to view in Google Earth.
More deforestation maps are available on the links below.
Rainforest soils are known as latosols. They are very nutrient poor because:
There is a thin layer of nutrients in the top layer of soil, where organic matter is decaying. Trees keep their roots close to the surface in order to capitalise on these nutrients. Leaching occurs as a result of the high precipitation and is increased greatly by deforestation. Minerals such as Calcium and magnesium are lost. Bedrock is weathered quickly. The characteristic red colour of the soil is due to iron and aluminium accumulating.
Deficit (D): A soil moisture deficit occurs when the demand for water exceeds that which is actually available . In other words, deficits occur when potential evapotranspiration exceeds actual evapotranspiration (PE>AE).
Surplus (S): Surplus water occurs when Precipitation exceeds PE and the soil is at its field capacity (saturated). There is more water than actually needed given the environmental conditions at a place.
The soil moisture budget is high in tropical ecosystems because precipitation is higher than potential evaporation.
A sample nutrient cycle Gershemel diagram for TER
The rainforest nutrient cycling is rapid. The hot, damp conditions on the forest floor allow for the rapid decomposition of dead plant material. This provides plentiful nutrients that are easily absorbed by plant roots. However, as these nutrients are in high demand from the rainforest's many fast-growing plants, they do not remain in the soil for long and stay close to the surface of the soil. If vegetation is removed, the soils quickly become infertile and vulnerable to erosion. If the rainforest is cleared for agriculture it will not make very good farmland, as the soil will not be rich in nutrients.
Net primary productivity (NPP)
Amount of energy made available by plants to animals, only at the herbivore level, and is expressed as kg/m2/yr.
Net primary productivity is affected by temperature, the availability of water, carbon dioxide (CO2), nutrients and the efficiency of conversion of light energy to the chemical energy of carbohydrates. The biomass of tropical rainforests is larger than that of other vegetation. Measurements show that tropical rainforests typically have biomass values on the order of 400 to 700 metric tons per hectare, greater than most temperate forests and substantially more than other vegetation with fewer or no trees.
Since water, light, and high temperatures are readily available in TER, and there is a dense concentration of green plants at all levels from the lower stories to the canopy, it is no wonder that these forests have very high levels of productivity.
Biodiversity is the the number and types of organisms in an habitat, ecosystem, region or environment. It can refer to genetic, species, or habitat variation at any scale. It is most frequently quantified as the number of species.
Tropical rainforests support the greatest diversity of living organisms on Earth. Although they cover less than 6% of Earth's surface, rainforests house an estimated 50% of all life on the planet's land masses. No one knows exactly how many species live in the world's tropical rainforests — estimates range from 3 to 50 million species — rainforests are the undisputed champions of biodiversity among the world's ecosystems, containing far higher numbers of species on a per-area basis.
In addition to the aesthetic beauty added to the world by many different organisms, biodiversity ensures the availability of a rich variety of genetic material that may lead to future agricultural or medical discoveries. As diversity is lost, potential sources of these materials may be lost. However, humans are destroying other species as a result of population growth, consumption, and technology. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other factors is especially threatening current global biodiversity.
Sustainable development: at the confluence of three constituent parts
Sustainability is defined as the quality of not being harmful to the environment or depleting natural resources, and thereby supporting long-term ecological balance. In more general terms, it is the endurance of systems and processes.
The deforestation, agriculture and mining, etc. in TER cause changes to the environment and are ultimately unsustainable. However, utilising the rainforest as a resource can bring wealth into the area, provide fuel and provide jobs for local people. Therefore the best method would be to manage the rainforest sustainably and this can be done in a variety of different ways:
Reducing Demand for Hardwood
The Amazon rainforest is the biggest tropical forest in the world, covering some 40% of the continent of South America, spread across nine countries and 6.6m square kilometres. About 65% of the Amazon rainforest lies within Brazil and is home to 13% of the country's population. Since 1970 almost 700,000 square kilometres of the Brazilian Amazon have been cleared.
Cattle ranching is the leading cause of deforestation in the Brazilian Amazon. Since 1990, the number of cattle in the Amazon has more than doubled from 26 million to 57 million in 2002. The rise in production has been driven by a huge rise in beef exports - combined with a revaluation of the Brazilian currency, the Real, which made cattle ranching more profitable for farmers and encouraged them to deforest.
However, the greatest emerging threat to Amazon rainforests and communities is industrial soy plantations which are claiming bigger swaths of the rainforest.
In recent years, the seemingly unstoppable expansion of soy farming in the Amazon had become one of the main threats to the world's largest rainforest. Brazil is the world's second-largest producer of soybeans. Brazilian soybean production has increased more than 3000% in the last 35 years. Brazil overtook the US as the world's leading exporter of soybeans in 2005/6 (USDA).
To grow soybeans, vast expanses of land are needed. Production is overtaking huge areas in fragile ecosystems. This threatens wildlife and biodiversity. It also adversely affects people, the global climate, water reserves and soil quality.
Europe buys half the soya exported from Amazon atate of Mato Grosso where 90% of rainforest soya is grow. The soya is used to produced animal feed to meet the European demand for cheap supermarket meat. In the past 20 years, 30 million hectares of forest and savannah, one-third of the state's area have been converted into land for agricultural purposes among which 70% is used to grow soybeans.
The Amazon rainforest contains the largest collection of living plant and animal species in the world. The diversity of plant species in the Amazon rainforest is the highest on Earth. It is estimated that a single hectare (2.47 acres) of Amazon rainforest contains about 900 tons of living plants, including more than 750 types of trees and 1500 other plants. A single bush in the Amazon may have more species of ants than the entire British Isles. In fact, 1/5 of all the birds in the world live in the rainforests of the Amazon. To date, some 438,000 species of plants, including 1,000 different trees have been registered in the region, and many more have yet to be catalogued or even discovered.
According to figures from WWF, it is also home to 427 different mammals, 1,294 birds, as well as 30 million people, including more than 220 indigenous groups. It is home to over 30% of global biodiversity.
Deforestation affects the habitats of many plants and animals. Loss of forests equates to a loss of many species and is also totally irreversible. Cascading changes in the types of trees, plants, and insects that can survive in the fragments rapidly reduces biodiversity in the forest that remains. The loss of Amazon rainforests where many species of life are found will mean that potential knowledge, whether medicinal, sustenance sources, or evolutionary and scientific information etc. could be lost.
Sustainable development for Amazon will meet the needs of Brazil's population without compromising the needs of future generations. To ensure this, the primary task is to balance economic growth with the preservation of the rainforest. Possible strategies include:
Rehabilitation and increased productivity of formerly forested lands
Increasing productivity of cleared rainforest lands is possible using improved technology to generate higher yielding crops, hence diminish the need to clear additional rainforest. Rehabilitation to restore the habitat for endangered species by reforestation. According to WWF, the species in Amazon have recovered from a low of 200 wild animals recorded in the early 1970s to 1,000th wild birth in 2001.
Expansion of protection areas
The extension of protection to critically important habitats within the Amazon region is key to maximizing survival of biodiversity in Brazil.
Good cattle ranching practices
Education, policy reform and law enforcement
Use of satellite technology and photography to check that any activities taking place are legal and follow guidelines for sustainability.
Making a Living
Watch the animation below to see how an indigenous farmer might rotate his crops over the years to ensure good yields on his land. Each year he clears and plants a new section of land, leaving the old section to regrow as secondary forest. When you see the ?, it's your turn to decide where to plant crops for the coming year. Click on the section of land you would clear next and check if that is a sensible choice.
If you are interested, you can try Coffee and Conservation game to balance agriculture earning and forest conservation. You can also try The Ecotourism Game to plan and manage a locally-controlled ecotourism project and test if it is ecotourism sustainable.
Click the red circled island to view past and projected deforestation in Borneo 1950 - 2020.
Borneo, the world's third largest island, is divided among three countries: Brunei, Malaysia and Indonesia. It accounts for just 1% of the world's land yet holds approximately 6% of global biodiversity in its rich, tropical rainforests. Its species range from the distinct Bornean orangutans and elephants to the giant pitcher plants and Rafflesia flowers. Yet this diversity is under threat - Borneo has already lost over half its forests, and a third of these disappeared in just the last three decades.
Majoy human activitives in the Borneo rainforest are logging, land clearing for timber, palm oil, pulp, rubber and minerals. Not only is the clearing on the rainforest for the palm oil plantations, they are creating new roads along the island of Borneo which allows immigrant settlers, hunters, and land speculators to access the new areas causing more damage to the trees, land and even the animal species.
The following presentation reveals the causes for deforestation in Borneo.
Palm oil is an edible plant oil which has become a common ingredient in many consumer products. Today, around 50% of the goods we use every day contain palm oil, from processed foods to candles, grooming products and “biofuels”.
Oil palm is highly productive, capable of yielding more oil from less land than any other vegetable oil, with relatively modest inputs. As a result, palm oil production has become an important source of income and a major part of the economy in the regions where it is grown.
Palm oil plantations are the leading cause of deforestation in Indonesia and Malaysia. These two regions account for over 90% of global production of palm oil. As palm oil is the cheapest vegetable oil, the demand for this commodity as a source of food and energy is expected to rise rapidly. The demand for food alone is expected to double in the next decade, and the Indonesian government has responded by setting a target to increase oil palm production from 20 million tonnes in 2009 to 40 million tonnes in 2020.
A scenario released by UNEP in 2002 suggested that most natural rainforest in Indonesia would be degraded by 2032. Given the rate of deforestation in the past five years, and recent widespread investment in oil palm plantations and biodiesel refineries, this may have been optimistic. New estimates suggest that 98% of the forest may be destroyed by 2022, the lowland forest much sooner.
The Borneo rainforest is 130 million years old, making it the oldest rainforest in the world and 70 million years older than the Amazon rainforest. Borneo is very rich in biodiversity compared to many other areas, there are:
Borneo is the centre of evolution and radiation of many endemic species of plants and animals. Subject to mass deforestation, the remaining Borneo rainforest is one of the only remaining natural habitat for the endangered Bornean Orangutan. It is also an important refuge for many endemic forest species, as the Asian Elephant, the Sumatran Rhinoceros, the Bornean Clouded Leopard, and the Dayak Fruit Bat. It is one of the most biodiverse places on earth. The WWF has stated that 361 animal and plant species have been discovered in Borneo since 1996, underscoring its unparalleled biodiversity. In the 18 month period from July 2005 until December 2006, another 52 new species were found.
But all these diversity would be lost if Borneo’s highland forests are fragmented. With threats coming from all sides (illegal logging, forest fires and the development of palm oil plantations), these forests have to be a continuous whole. Successful rainforest conservation requires inter-connected forests, without which hundreds, or even thousands, of species would become extinct.
By piecing together a complex ecological puzzle, biologist Willie Smits believes he has found a way to re-grow clearcut rainforest in Borneo, saving local orangutans — and creating a thrilling blueprint for restoring fragile ecosystems.
Destruction of Borneo's rainforest would seriously affect the region’s water catchment role and would impact the region’s unique biodiversity. The unsuitability of the terrain may also result in large-scale soil erosion, flooding and increase the risk of fire.
In Borneo, sustainable development is possible, with greater benefits for everybody, including Indigenous communities and the poor. Practical steps could be taken towards sustainable development, such as:
• Environmental planning: Prepare coherent land use plans, including a category for “degraded land”, (to facilitate agricultural development on existing cleared land rather than natural forest), expand community forests and implement protection of river catchments.
• Protected areas: Protect natural habitats, and improve ‘passageways’ between protected areas.
• Forestry: Reduce impact logging and implement an international certification of sustainable forest management. Limit plantations to highly degraded or deforested areas that don’t have a high conservation value. Protect inactive forestry land to reduce degradation. In natural forest areas after logging, undertake forest restoration.
• Palm oil plantations: No expansion of palm oil plantations in any area of natural forest. Improve management practices, including fertilizer and pesticide application management in accordance with the recommendations of RSPO.
• Mining: Mining follows international good practice guidelines, with improved waste management treatment reducing impacts on air and water quality.
• Agriculture: Maintain and restore soil quality through sustainable agriculture practices., Reduce use of chemical fertilizers and expand upon the biodiversity gene bank to provide wild varieties that may be crossbred to ensure greater resilience to pests and diseases.
• Energy: Reduce domestic consumption of energy (especially of fossil fuels), expand renewable energy use to help reduce the costs and impacts of using fossil fuels.
• Biodiversity-based industries: Biodiversity-based industries either depend on biodiversity for their core business (for example, sustainability produced eaglewood or other non-forest products) or contribute to biodiversity conservation through their activities (for example, protecting and restoring abandoned logging areas). These businesses can reduce deforestation and biodiversity loss in the Borneo.
• Innovative green sectors: New business models build local economies, for example, using ‘waste products’ from waste produced by current industries.
The following file summarises the topics in this section. You can zoom in, or click the pdf file link below to view the file in full scale.