tropical rainforests

tropical rainforests

1. WHAT ARE TROPICAL RAINFORESTS

   • CHARACTERISTICS OF TROPICAL RAINFORESTS
     • diversity of plant species
       • some studies suggest that an area of 0.01 sq km in the amazon rainforest in SA contains about 300 different species
     • structure of the tropical rainforest
       • three layered structure:
         • emergent layer (50m): formed by the crowns of the emergent trees, which are usually very tall, straight and smooth trunks with few branches
         • canopy layer (30m): lianas and epiphytes grow in this layer
         • undergrowth layer (20m): plants here are small, thin and widely spaced due to lack of sunlight because much of the sun's rays are blocked by the canopy above
     • adaptation of plants
       • specific features to adapt to the climatic conditions eg. leaves --> broad to capture sunlight for photosynthesis

2. USES OF TROPICAL RAINFORESTS

   • WATER CATCHMENT
     • refers to an area drained by a river and the smaller rivers that flow into it
     • TRs stop rain from reaching the ground directly, water drips from the trees and seeps into the groundwater in the soil
   • GREEN LUNGS OF THE EARTH
     • TRs absorb carbon dioxide from the atmosphere and release oxygen through the process of photosynthesis
   • HABITAT TO FLORA AND FAUNA
     • 1. sunlight is being converted by the plants into energy and food through photosysnthesis, the plants in turn are eaten by animals 2. the continuous canopy is a habitat where other organisms can grow and live in
   • HABITAT TO INDIGENOUS PEOPLE
     • about 60 million indigenous people are wholly dependent on the forest, many of them have been living in TRs for years
   • SOURCE OF TIMBER
     • provide wood for fuel in countries where people depend on fire to cook
   • MEDICAL APPLICATION
     • TRs known as 'the world's largest pharmacy' as they have been a huge source of medicine

3. DEFORESTATION

   • cutting down and removal of all or most of the trees in a forested area, if not managed properly can result in the permanent destruction of trees
   • DISTRIBUTION OF TRs
     • found in equatorial climates, TRs require abundant sunlight, high temperatures and heavy rainfall throughout the year
     • IN SINGAPORE, many parts of Singapore were originally covered with rainforests, but deforestation resulted in there only being two large areas of TRs left, the Central Catchment Nature Reserve and the Bukit Timah Nature Reserve
   • DISTRIBUTION OF DEFORESTED AREAS
     • happens in almost every area where TRs are found, eg. Borneo
   • CAUSES
     • AGRICULTURAL ACTIVITIES, shift from subsistence farming --> commercial farming eg. Borneo
     • CATTLE RANCHING, large areas of rainforest are cleared to create land for cattle to graze eg. Amazon
     • LOGGING, cutting down of trees for timber, commercial logging of tropical hardwoods in SEA for furniture, building materials eg. China
     • MINING, previous metals and gemstones are found beneath many TRs, forests are cleared to establish mines to extract these materials
   • IMPACTS
     • ENVIRONMENTAL IMPACT
       • LOSS OF BIODIVERSITY, due to the destruction of habitats of plants and animals --> extinction of certain species
       • LOSS OF WATER CATCHMENT AREAS, clearing of trees disrupt the water cycle --> drier climate and drier soils in the region eg. Amazon
       • INCREASED RISK OF FLOODING, without TRs the rainwater falls directly on the ground and flows over the surface as surface runoff. SOIL EROSION, tree roots hold the soil to the ground and keep the ground stable, removal of trees result in the soil being exposed to erosion AND SEDIMENTATION, increased sedimentation --> decrease in the surrounding water quality
       • ENHANCED GREENHOUSE EFFECT, removal of rainforests --> decreased CO2 capture --> increased in CO2 levels in the atmosphere which function as a greenhouse gas
     • ECONOMIC IMPACT
       • DEPLETION OF NATURAL RESOURCES, rapid deforestation destroys the rainforest faster than it can replenish itself --> many natural resources provided by the rainforest being depleted
     • SOCIAL IMPACT
       • IMPACT ON INDIGENOUS PEOPLE, they lose their homes and are forced to adapt to a new way of living --> their tribes to disperse and their cultures to dissapear
   • HOW TO MANAGE DEFORESTATION
     • IN THE AMAZON
       • PROTECTION OF FORESTED AREAS, eg. the Central Amazon Conservation Complex is the largest protected area in the Amazon Basin which has one of the highest biodiversities in the world
       • REFORESTATION, planting of trees in areas where the original forest has been cleared, involves NPOs, companies and local communities
       • CONTROLLED LOGGING, careful management of forests that are being logged, allows logging only in certain areas and in a sustainable manner eg. through penalties and education & research programmes
       • PUBLIC EDUCATION, people need to be told of the importance of rainforests and ways to contribute to conserving them
     • IN SINGAPORE
       • PROTECTION OF FORESTED AREA, protection through establishment of nature reserves like the BTNR and CCNR, and through legislation like the Parks and Trees Act 2005
       • REFORESTATION, intended to conserve and recover native plant species, done in botanic gardens and through projects like the Forests of Giants
       • PUBLIC EDUCATION, done by the Singapore Government to promote people's understanding of the forest in three key ways
     • BENEFITS AND CHALLENGES
       • protected areas are important in the conservation of our indigenous ecosystems and native biodiversity BUT protected areas are not fenced and are still vulnerable to human impact
       • soil fertility can be improved, thus sustaining plant growth in the long term BUT reforestation projects can be expensive and time-consuming
       • greater control of illegal logging can result in a decrease in deforestation BUT hard to implement especially over a large area eg. the Amazon
       • education has far-reaching effects, especially in the long term BUT turning environmental awareness into personal behaviour and action is difficult