Tropical Biomes & Sustainable Development (SL IB Environmental Systems & Societies (ESS))

Tropical Biomes

• Tropical biomes are mainly found in a band between 15° north and 15° south of the equator within the equatorial climate zone
• Covering only 6% of the Earth's surface, the main areas covered by tropical ecosystems are in the following countries:
• Amazon - the largest remaining rainforest on Earth usually associated with Brazil but covers parts of seven other countries in South America
• Central America - including parts of Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama
• Central Africa -  including Cameroon, the Central African Republic, the Republic of Congo, the Democratic Republic of Congo (DRC), Equatorial Guinea and Gabon
• Indo-Malaysia - including Malaysia, Indonesia and a number of other countries in South-East Asia

Distribution of the equatorial climate

Characteristics of Tropical Biomes

Exploitation in Tropical Biomes

• Tropical biomes (particularly tropical rainforests) have some of the highest levels of biodiversity of any ecosystem
  • The wet and warm climate means there is year-round growth 
  • Wide variety of plants provides a range of habitats and food 
  • Rapid nutrient cycling increases plant growth
  • Lack of human activity in the past meant that plants and animals have remained undisturbed

• The abiotic and biotic components in tropical rainforests are all interlinked and changes in one can lead to changes in the others - this is known as interdependence

Factors contributing to high biodiversity in tropical rainforests

• Most tropical biomes occur in LEDCs and therefore there is a conflict between exploitation, sustainable development and conservation
• Current threats in tropical biomes mainly revolve around the removal and degradation of rainforest ecosystems. This deforestation is due to human activities, including:
• Agriculture, particularly large scale slash and burn 
• Mining
• Hydroelectric power
• Logging
• Road building and settlements
• Wildfires (although natural, increasing frequency and severity is linked to climate change)

Human causes of deforestation

• The interdependence of the rainforest components means that when one element is affected it then impacts all the other components
• For example, a decline in one species (especially if it is a keystone species) can lead to a decline in other species 
• The Zam tree produces seeds which are food for agouti, who disperse the seeds 
• The agouti is hunted for meat reducing their populations this means fewer seeds are dispersed
• Fewer new Zam trees will germinate and so there is less food for leaf cutter ants which in turn means less food for the tree frogs and the snakes which prey on the frogs
• The Zam tree is pollinated by a particular species of butterfly. Without the flowers the numbers of the butterfly species will decline - this also affects the beetles which lay their eggs in the butterfly faeces

• Plant and animal species may become extinct - this may happen to some before they are even discovered
• Important medicinal plants and potential medicinal plants may become extinct
• Indigenous communities may be forced to abandon their traditional lifestyle due to the lack of food to hunt and gather
• In summary, unsustainable exploitation in tropical biomes results in massive losses of biodiversity and their ability to perform globally important ecological services, such as carbon sequestration and climate regulation

Tropical rainforest food webs are highly complex with high interdependence amongst species

Coral Reefs of Southeast Asia

Photo by yang wewe on Unsplash 

Coral reefs are ecosystems under threat

• An example of an area of great biological significance that has been impacted by human activity is the coral reefs of Southeast Asia, particularly the reefs surrounding Indonesia and the Philippines
  • These coral reefs are some of the most diverse ecosystems on the planet, providing habitat for thousands of species of fish, invertebrates, and other marine organisms
  • However, human activity in the form of overfishing, pollution, and climate change is causing significant damage to these fragile ecosystems

• Overfishing is a major threat to the biodiversity of coral reefs in Southeast Asia, with many species of fish and other marine organisms being overexploited for food and other uses
  • This has led to declines in populations of many important species and disruptions to the ecological balance of the reef ecosystem

• Pollution from land-based activities, such as agricultural runoff and sewage discharge, is also a significant threat to coral reefs
  • This is leading to reduced water quality and increased stress on the corals

• Finally, climate change is causing the ocean to warm and become more acidic
  • This is leading to coral bleaching and death

• The conflict between exploitation, sustainable development, and conservation in the coral reefs of Southeast Asia is complex and challenging
  • Economic interests in the form of tourism and fishing drive the exploitation of these ecosystems, while conservation efforts seek to protect them
  • Sustainable development seeks to balance economic growth with environmental protection, but it is often difficult to achieve in practice

• One approach to addressing this conflict is through the establishment of marine protected areas (MPAs)
  • MPAs can help to protect coral reef ecosystems by limiting fishing and other human activities, allowing damaged reefs to recover and promoting biodiversity
  • However, the success of MPAs depends on effective management and enforcement, which can be difficult to achieve in practice

Eastern Himalayas

Photo by Uriel Soberanes on Unsplash 

Snow leopards are vulnerable species found in the Eastern Himalayas that are threatened by illegal hunting

• Another example of an area of biological significance is the Eastern Himalayas, which is home to a vast array of plant and animal species found nowhere else in the world
• The following are some of the ways human activity has affected the biodiversity of this region:
• Deforestation:
  • The Eastern Himalayas have experienced significant deforestation, primarily for agriculture, timber, and fuelwood
  • Deforestation has led to habitat loss and fragmentation, which can lead to the displacement or extinction of species

• Poaching and hunting:
  • The Eastern Himalayas are also home to many endangered and vulnerable species, including tigers, snow leopards, and rhinoceroses
  • Poaching and hunting of these animals for their meat, hides, and other body parts have put many of these species at risk of extinction

• Climate change:
  • Many species in the Eastern Himalayas are highly adapted to the specific temperature ranges and other climatic conditions in this area
  • This means they are vulnerable to climate change, which can affect the growth and survival of many plant and animal species in the region

• The conflict between exploitation, sustainable development, and conservation in the Eastern Himalayas is highly complex
  • Economic development and poverty reduction are important goals, and the region's resources can contribute to these goals
  • However, this often comes at the expense of environmental protection and conservation
  • Sustainable development seeks to balance economic growth with environmental protection, but it can be challenging to achieve in practice

• The governments of the countries that share the Eastern Himalayas have made efforts to protect the region's biodiversity, including the establishment of protected areas and the implementation of policies to reduce deforestation and illegal poaching
  • However, these efforts have been met with resistance from powerful interest groups, including logging companies and poachers