Ecology and Ecosystems

Introduction to Environmental Studies

• Environmental studies is a multidisciplinary academic field that studies human interaction with the environment.
• The study of functional intricacies of the environment in relation to an organism is known as environmental studies.
• The field has various branches, including autecology and synecology.

Scope and Importance of Environmental Studies

• Environmental studies creates awareness about renewable and nonrenewable resources.
• It provides knowledge about ecological systems, cause and effect relationships, and biodiversity richness.
• The study helps understand natural disasters, environmental issues, and skills and technologies to address them.
• It also enables citizens to make informed decisions about environmental protection and sustainable utilization of resources.

Elements of Environment

• The environment consists of three elements: physical, biological, and cultural.
• Physical elements include space, landforms, water bodies, soil, rocks, and minerals.
• Biological elements include plants, animals, and microorganisms present in the biosphere.
• Cultural elements include economic, social, and political factors that are essentially human-made features.

Multidisciplinary Nature of Environmental Studies

• Environmental studies encompasses subjects like physics, chemistry, biology, geography, anthropology, economics, and statistics.
• It addresses various aspects, including pollution, biodiversity, deforestation, desertification, and waste management.

Sustainability and Sustainable Development

• Sustainability refers to the ability of people to coexist on earth without compromising the ability of future generations to meet their needs.
• Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.
• It has three dimensions: environmental, economic, and social.

Ecosystems

• An ecosystem is a natural unit that includes a community of organisms and their complex environmental factors, interacting to produce a stable system.
• Ecosystems can be classified into natural and artificial ecosystems.
• Natural ecosystems are classified into terrestrial and aquatic ecosystems.
• Terrestrial ecosystems include forest, grassland, and desert ecosystems.
• Aquatic ecosystems include saltwater and freshwater ecosystems.

Structure and Functions of Ecosystems

• An ecosystem consists of two major interacting structural components: abiotic and biotic components.
• Abiotic components include non-living factors like light, soil, air, and water.
• Biotic components include living organisms like microorganisms, plants, and animals.
• Autotrophs are organisms that produce their own food using sunlight, carbon dioxide, and water.
• Heterotrophs are organisms that cannot produce their own food and are dependent on autotrophs or other heterotrophs.

Functions of Ecosystems

• The flow of energy in an ecosystem occurs through various trophic levels.
• The ecosystem also involves the cycling of materials like carbon, oxygen, and nutrients.
• Decomposers play a crucial role in the ecosystem by breaking down organic matter and recycling nutrients.### Biogeochemical Cycle
• A cyclical passage in which nitrogen, oxygen, sulphur, phosphorus, and water circulate between living and non-living components of an ecosystem.

Flow of Energy

• The main source of energy for an ecosystem is light energy derived from the sun.
• The passage of energy comprises 6 processes:
  • Autotrophs (green plants) convert radiant energy into chemical energy through photosynthesis.
  • Part of this chemical energy is used for metabolic activities, with some energy lost as heat.
  • Autotrophs become the food and energy source for herbivores (primary consumers).
  • Energy is again lost as heat in the form of compounds such as urea and uric acid.
  • Carnivores (secondary consumers) consume herbivores and use them as a source of energy.
  • Decomposers degrade dead bodies of plants and animals, returning energy to the abiotic environment.

Trophic Level

• The flow of energy at successive stages in an ecosystem is known as a "trophic level".
• Trophic level comprises a group of organisms that obtain their food in the same general way.
• Typically, an ecosystem has 3 to 4 trophic levels through which energy flows.

Food Chain

• A food chain is a sequence of organisms in which one organism feeds on the preceding one.
• The trophic structure of an ecosystem is the basis of a food chain.
• A food chain consists of producers, herbivores, carnivores, and decomposers.

Food Web

• A food web is multiple feeding interactions between each species.
• A food web consists of all the food chains in a single ecosystem.
• Each living thing in an ecosystem is part of multiple food chains.

Aquatic Ecosystem

• An aquatic ecosystem is an example of a water-based ecosystem.
• Aquatic ecosystems are divided into saltwater and freshwater ecosystems.
• Saltwater ecosystems include marine and estuarine habitats.
• Freshwater ecosystems are divided into lentic (ponds and lakes) and lotic (rivers and streams) systems.

Pond Ecosystem

• A pond ecosystem is a type of aquatic ecosystem.
• Abiotic components of a pond ecosystem include light, water, and dissolved salts and gases.
• Biotic components of a pond ecosystem include autotrophs (producers), heterotrophs (consumers and decomposers), and macroscopic plants.

Functional Aspect of Pond Ecosystem

• Producers synthesize food through photosynthesis.
• Energy is passed sequentially from primary to tertiary consumers.
• Decomposers are responsible for recycling minerals in the ecosystem.

Ecological Succession

• Ecological succession is the successive replacement of communities in an area over time.
• There are two types of succession: primary succession (in barren areas) and secondary succession (in areas where vegetation has been destroyed).
• The process of succession involves the replacement of pioneer species with late successional species, ultimately leading to a climax community.

Natural Resources

• Natural resources are living and non-living factors of nature used by humans for various purposes.
• Types of natural resources:
  • Biotic resources (come from living things or organic materials, e.g. plants, animals, fossil fuels)
  • Abiotic resources (come from non-living and inorganic materials, e.g. land, air, sunlight, water, minerals)
• Natural resources can be classified based on the stage of development:
  • Potential resources
  • Actual resources
  • Reserve resources
  • Stock resources### Natural Resources
• Potential resources: resources that remain in the earth's crust and may be used in the future, e.g. petroleum, solar power, wind power, mineral oil, and paper.
• Actual resources: resources that have been surveyed, quantified, qualified, and are currently being used, e.g. wood and wind.
• Reserve resources: part of an actual resource that can be developed profitably in the future, e.g. wind, soil, mines, and trees.
• Stock resources: resources that have been surveyed but cannot be used due to lack of technology, e.g. gases like hydrogen and sea water.

Land Resources

• Land resource: land available for exploitation, e.g. non-agricultural lands for buildings, developing townships, etc.
• Land use: characterization of land based on what can be built on it and what the land can be used for, e.g. determining what sort of community, environment, or settlement can be used on a specific type of land.
• Land use change: process that transforms the natural landscape by direct human-induced activities, e.g. settlements, commercial, and economic uses, and forestry activities.

Land Degradation

• Definition: change in the characteristic and quality of soil that adversely affects its fertility, e.g. loss of natural fertility, less vegetation cover, changes in soil characteristics, pollution of water resources, and changes in climatic conditions.

Soil Erosion

• Definition: detachment and transportation of soil, especially the fertile top soil, by natural agencies like water and wind.
• Types of soil erosion:
  • Water erosion: transportation of soil by flowing water, e.g. sheet erosion, rill erosion, and gully erosion.
  • Wind erosion: transportation of soil particles by wind, e.g. suspension, saltation, and surface creep.
  • Stream bank or riparian erosion: erosion of river banks due to flood water.

Methods of Soil Conservation

• Protecting the top soil from direct impact of rain drops.
• Decreasing the speed of surface run-off of water.
• Reducing the velocity of wind.
• Increasing the moisture and organic matter content of soil.

Desertification

• Definition: gradual process by which a fertile, productive land is converted into unproductive land and finally into barren desert-like area.
• Causes of desertification:
  • Overgrazing
  • Deforestation
  • Farming practices
  • Excessive use of fertilizers and pesticides
  • Overdrafting of groundwater
  • Urbanization and other types of land development
  • Climate change
• Effects of desertification:
  • Decrease in crop yield
  • Increase in hunger
  • Scarcity of water
  • Decrease in biodiversity
  • Endangerment of species

Forest Resources

• Definition: complex land ecosystems that support a wide variety of plants, trees, and animals.
• Types of forests:
  • Evergreen forests
  • Deciduous forests
  • Scrub forests
• Non-timber forest products:
  • Fruits and nuts
  • Vegetables
  • Fish and game
  • Medicinal plants
  • Resin and essences
  • Barks and fibres, e.g. bamboo, rattans, and palms

Water Resources

• Definition: most abundant, inexhaustible renewable resource.
• Uses of water:
  • Domestic
  • Agricultural
  • Industrial
  • Hydropower
  • Drinking water

Over-Utilization of Surface and Ground Water

• Causes of over-utilization:
  • Increased population and industrial growth
  • Decreased rainfall
  • Increased extraction of groundwater
  • Decreased water table
  • Decreased pressure in aquifers
  • Saltwater intrusion
  • Earthquakes and landslides

Flood and Drought

• Definition: extreme negative situations caused due to water imbalances.
• Causes of flood:
  • Ice and snow melt
  • Lack of vegetation
  • Broken dams
  • Heavy rains
  • Climate change
  • Emission of greenhouse gases
• Effects of flood:
  • Harm to wildlife
  • Contamination and disease
  • Loss of goods and life
  • Soil erosion
• Definition of drought: prolonged period of dryness in the natural climate cycle.
• Causes of drought:
  • Overpopulation
  • Over cultivation
  • Deforestation
  • Less rainfall
• Effects of drought:
  • Hunger
  • Lack of water
  • Wildfire
  • Damage to wildlife