Impacts of Human Activity on Tropical Rainforests (Cambridge (CIE) AS Environmental Management)

Human Impacts on Tropical Rainforests

• Tropical rainforests 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 of tropical rainforest ecosystem are in the following countries:

  • Amazon, which is the largest remaining rainforest on Earth (usually associated with Brazil but covers parts of seven other countries)

  • 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

• Current threats in tropical biomes mainly revolve around the removal and degradation of tropical rainforests through deforestation:

  • Deforestation involves the clearing of large areas of tropical rainforests for various purposes, leading to fragmentation where isolated patches of forest remain

• Deforestation is caused by many different human activities, including:

  • Fuel wood and timber collection

  • Agricultural expansion particularly large scale slash and burn 

  • Mining (mineral extraction)

  • Hydroelectric and reservoir projects

  • Road building and settlements

  • Wildfires (although natural, increasing frequency and severity is linked to human-driven climate change)

• Brazil, India, Indonesia and Malaysia are experiencing the highest levels of deforestation in the world

Climate Change

• In addition to direct threats to the tropical rainforest there are indirect threats

• Climate change is the most significant of these:

  • The rainforest is dependent on high levels of precipitation 

  • Climate change negatively impacts the amount and frequency of rainfall

• Recent droughts have occurred in 2005, 2010, 2015, 2016 and 2020

• Droughts can lead to the rainforest emitting carbon dioxide rather than absorbing it

• Droughts lead to stress on tropical rainforest ecosystems due to:

  • Decomposer organisms and insects dying as the leaf litter is too dry:

    • This will lead to a decrease in soil fertility and negative impacts on the nutrient cycle

  • Trees and plants lose more leaves than usual, decreasing the supply of food for primary consumers:

    • Fewer leaves will mean less evapotranspiration, which may further decrease the amount of rainfall

  • Lack of food for herbivores reduces animal populations and impacts on the food web

  • Reduced nutrient input into streams and rivers impacts on tropical rainforest aquatic life

• Higher temperatures may lead to the death of animals in large numbers e.g. whole colonies of flying fox bats have been killed by extreme high temperatures

Managing Human Impacts on Tropical Rainforests

Legislation & International Agreements

• Implementation of laws and international agreements to regulate and mitigate human impacts on tropical rainforests:

  • Examples include national forestry laws, the Convention on Biological Diversity (CBD, 1992) and the Paris Agreement (2015)

• Evaluation:

  • Strengths: Legislation provides a legal framework for protecting forests, setting standards for sustainable resource use and enforcing penalties for illegal activities

  • Weaknesses: Enforcement may be challenging due to limited resources, corruption and conflicting interests between stakeholders

Sustainable Harvesting

• Practices that promote the extraction of forest resources in a manner that maintains ecosystem health and biodiversity:

  • Includes selective logging, agroforestry, and community-based forest management

  • Agroforestry combines agriculture with forestry, which means some trees remain, which:

    • Decreases deforestation

    • Provides shade as well as increases infiltration and interception, which reduces soil erosion

    • Provides organic matter from the trees and adds nutrients to the soil

    • Increases biodiversity due to the variety of plants grown

• Evaluation:

  • Strengths: Sustainable harvesting can generate income for local communities, reduce pressure on primary forests, and support long-term forest conservation

  • Weaknesses: Requires careful planning, monitoring and enforcement to prevent overexploitation, habitat degradation and loss of biodiversity

Debt for Nature Swaps

• These are formal, legally binding agreements where a portion of a country's foreign debt is forgiven or restructured in exchange for conservation commitments:

  • Funds freed up from debt payments are allocated to conservation projects

  • For example, in 2010 the USA converted US$13.5 million of debt from Brazil into a fund to support the protection of the rainforest

• Evaluation:

  • Strengths: Debt-for-nature swaps provide financial incentives for forest conservation, promote international cooperation and support local communities

  • Weaknesses: Implementation challenges include ensuring transparency, equity and long-term funding for conservation initiatives

Creation of Protected Areas

• Establishment of national parks, reserves and protected areas to conserve biodiversity and ecosystem services:

  • Areas may be designated for strict protection, sustainable use, or multiple land-uses

• Evaluation:

  • Strengths: Protected areas provide critical habitat for endangered species, safeguard ecosystem functions and promote ecotourism and scientific research

  • Weaknesses: Limited resources for management and enforcement, conflicts with local communities over land rights and encroachment from illegal activities pose challenges to effective protection