Negative changes in composition, structure and functioning of an ecosystem is known as ecosystem degradation. Degradation in ecosystem reduces the biodiversity and the rate of nutrient cycle of the ecosystem. Ecosystem degradation can take place because of natural calamities or human activities, or both. The impact of natural calamities is quite intense, as they affect large geographical areas in a limited time. Some natural calamities are of common occurrence while others are restricted only to specific areas. However, we cannot stop ecosystem degradation happen through natural calamities.
Ecosystem degradation due to natural calamities
Natural calamities like forest fires, floods, earthquakes, droughts, famines, etc. degrade our ecosystem.
1. Forest fires:
• Forest fires destroy large regions of forest.
• Rare species of plants or trees are destroyed. Many important commercial trees are destroyed during forest fires.
• Biodiversity gets lost.
• Forest fires affect people's livelihood, which are directly dependent on the forest resources.
• Resident animals are killed or forced to migrate.
• Pollutants can be emitted due to forest fires.
2. Floods: Floods are caused due to high torrential rains or release of excess water from dams or melting of snow.
• Crops in the flooded farms get affected.
• Floods can cause spread of water-borne diseases like malaria, typhoid, etc due to mixing of sewage water.
• Floods can death of a large number of animals and humans.
• Animals get drowned in flood water. Many animals migrate because of floods.
• Severe earthquakes can change the topography of the affected areas.
• Plants, animals and human beings die due to earthquakes.
• They also change water levels of reservoirs like wells, lakes, or rivers.
4. Droughts: A period of unusual dry weather arising due to lack of water is called drought.
• Soils dry out plants and animals die under the conditions of drought.
• Droughts affect agriculture adversely and destroy crops and livestock.
• The flow of streams and rivers declines. Chances of soil erosion also increase due to droughts.
• Fall in the levels of water in lakes, wells and reservoirs.
5. Famines: Extreme shortage of food in an area is called famine.
• Roots of plants hold soil tightly. Due to absence of plants, soil becomes more prone to erosion and degradation.
• Famines affect ecosystems by increasing pressure on resources, both in the areas of drought as well as the places to which people and animals migrate.
• Animals have to migrate from the famine affected area in search of food. People also have to migrate in search of food and job.
Ecosystem destruction due to human activities
Human activities such as mining/conversion of the wetlands into human settlements, uncontrolled hunting and migration, etc. can cause destruction of the eco-systems. The main types of causative factors of ecosystem degradation by human activities are as follows:
1. Population explosion
4. Industrialization and transportation
5. Shifting cultivation
7. Construction of dams
1. Population explosion
• As the population grows, the basic essentials needed for survival is increased. To meet these increasing needs man overharvests the eco-systems.
• Due to change in lifestyle, use of synthetic materials has also increased. Some synthetic materials cannot be recycled in natural cycles and contribute to increasing quantity of wastes.
2. Migration: The movement of population from one place to another place because of specific reasons is called migration.
• Migration creates imbalance of population.
• The imbalance of population in the newly migrated area affects eco-systems surrounding that area.
3. Urbanisation: The process of formation of large urban areas is called urbanisation.
• Cities grow at the cost of natural eco-systems and therefore it results in environmental degradation. Due to this, the ecosystems are destroyed completely.
4. Industrialization and transportation:
• Industries require large amount of raw materials such as metal ores, wood and sand.
• This demand for wood is accomplished by converting natural forests into plantations.
• Various pollutants from various industries are released into the environment. These pollutants, like mercury enter the food chain and are magnified through the process of biomagnification. This process disturbs the natural balance of the ecosystem.
• Dumping of earth and rocks, after the process of extracting ores, onto forest areas or wetlands causes disturbances in balance of eco-system.
• Construction of highways and railways across forest disturbs the natural habitats of wildlife and also affects migration of animals.
5. Shifting cultivation:
• Shifting is also known as 'slash-and-burn' system of agriculture. The forest land is cleared by felling trees and later burning the leaves and twigs in the spread-out manner as they lie. This makes the land cultivable.
• The land is abandoned after a few years because such lands are only temporarily fertile.
• The farmers then move onto the adjoining areas and repeat the process.
• After a considerable lapse of time (some 20 years or so) the abandoned patch grows into a forest land naturally. The farmers come back to 'slash-and-burn' the patch again.
• In modern times, the interim period between 'slash-and-burn' has significantly increased. It has degraded the eco-system severely.
6. Tourism: Tourism is practiced for different purposes like sight-seeing, recreation and pilgrimage.
• Tourism supports the livelihood of thousands of people all over the world.
• It has detrimental effects on local ecosystems.
• Hunting, poaching and disturbing the animals cause reduction in wild life.
7. Construction of dams:
• Dams create large reservoirs of water.
• The ecosystem of the upstream side is forcibly converted into an aquatic ecosystem.
• The downstream ecosystem is changed from a flowing water system to an ecosystem of dry bed of sand and stones.
• Displacement of native people takes place due to construction of large dams and this leads to increased pressure on the ecosystem in the neighbouring areas.
8. Wars: Wars occur as a result of competition and conflict between nations.
• Wars take heavy toll of life.
• Natural resources are used during wars. Natural ecosystems are destroyed partially or completely.
Natural calamities and certain human activities prove harmful to natural ecosystems. However, we cannot control degradation caused due to natural calamities but can control destruction caused from man-made activities. Natural ecosystems play a key role in maintaining environmental balance in the biosphere. Hence, the ecosystems must be protected.