Understanding Ecosystems

Concept of An Ecosystem

• An ecosystem is a specific geographical area with a unique landscape like a forest, grassland, desert, wetland or coastal area.
• An ecosystem's nature is influenced by features like hills, mountains, plains, rivers, lakes, coastal areas, or islands, as well as climatic conditions like sunlight, temperature, and rainfall.
• The non-living components, the abiotic components, shape the conditions that support the plant and animal communities.
• The living component of the ecosystem is known as the biotic component.
• Ecosystems are categorized as either terrestrial (land-based) or aquatic (water-based), forming the two major habitat types for Earth's organisms.

Understanding Ecosystems

• Natural ecosystems include forests, grasslands, deserts, and aquatic environments like ponds, rivers, lakes, and oceans.
• Man-modified ecosystems include agricultural land and urban or industrial areas.
• Key features to analyze an ecosystem:
  • Appearance: Describe specific characteristics of the ecosystem.
  • Structure: Is it a forest, grassland, water body, agricultural, grazing, urban, or industrial area?
  • Species Composition: List the prevalent plants and animals, documenting their abundance and numbers.
  • Ecosystem Functioning: Observe and record the ecosystem's components, including abiotic factors (air, water, climate, soil) and biotic factors (plants and animals).
  • Interconnections: Observe how plants, herbivores, and carnivores form food chains, ultimately forming the web of life that humans depend on.

Ecosystem Degradation

• Ecosystems are crucial to life itself, providing products and essential ecological processes.
• Human activities often disrupt ecosystems, leading to the extinction of plant and animal species.
• 'Keystone' species, if eliminated, can severely impact the ecosystem's stability.
• Extinction is driven by land-use changes:
  • Deforestation for timber
  • Wetland drainage for agriculture
  • Conversion of semi-arid grasslands into irrigated fields
• Pollution from industries and urban waste also contribute to species extinction.
• Resource depletion stems from:
  • Population growth requiring resources
  • Affluent societies with high consumption and waste
• Resource extraction at the expense of natural ecosystems disrupts their vital functions.

Resource Utilisation

• Traditional societies generally utilized their environment sustainably.
• While societal inequality in resource use existed, a limited number of individuals consumed a large proportion of resources.
• In recent times, the population of affluent societies has grown rapidly, leading to significant resource inequality.
• Unsustainable resource extraction has intensified in the last century.
• The economically well-off have increased their use of forest products, while those living in forest regions have become impoverished.
• Large irrigation projects have benefited some areas but negatively impacted those relying on natural water sources.
• Equitable distribution of natural resources is crucial to reduce pressure on ecosystems.

Structure and Functions of an Ecosystem

• Structural aspects:*
• Inorganic components: Carbon, Nitrogen, Carbon Dioxide, Water
• Organic compounds: Proteins, Carbohydrates, Lipids (connect abiotic and biotic components)
• Climatic regimes: Temperature, Moisture, Light, and Topography
• Producers: Plants
• Macro consumers: Phagotrophs (large animals)
• Micro consumers: Saprotrophs, Absorbers (fungi)
• Functional aspects:*
• Energy cycles
• Food chains
• Diversity (interconnections between organisms)
• Nutrient cycles (biogeochemical cycles)
• Evolution

Producers, Consumers, and Decomposers

• Producers: Plants manufacture their food using solar energy.
• Herbivores: Primary consumers that consume producers.
• Carnivores: Secondary consumers that feed on herbivores.
• Decomposers: Organisms like worms, insects, bacteria, and fungi break down dead organic matter, returning nutrients to the ecosystem, making them essential for nutrient cycling.

Energy Flow In the Ecosystem

• Ecosystems are governed by interrelated mechanisms impacting human life, including the water cycle, carbon cycle, oxygen cycle, nitrogen cycle, and energy cycle.
• Each ecosystem has unique abiotic and biotic components, impacting its functions.
• All ecosystem functions are connected to plant and animal growth and regeneration.
• Cycles:*
• Water Cycle: Rainfall is vital for plant and animal life.
• Carbon Cycle: Carbon is essential for plant and animal growth. Plants regulate oxygen and carbon dioxide levels in the atmosphere.
• Oxygen Cycle: Plants produce oxygen through photosynthesis, while animals use oxygen for respiration.
• Nitrogen Cycle: Nitrogen-fixing bacteria and fungi in soil provide plants with nitrogen as nitrates, crucial for protein synthesis.
• Energy Cycle: Solar energy is converted by plants into plant material, driving energy flow through the ecosystem.

Food Chains, Food Webs, and Ecological Pyramids

• Food chains represent energy transfer through eating and being eaten.
• Energy is lost as heat during each transfer.
• Food chains are interconnected to form food webs.
• Each step in the food web is called a trophic level:
  • Green plants occupy the first level.
  • Herbivores occupy the second level.
  • Carnivores occupy the third level.
  • Secondary carnivores occupy the fourth level.
• These trophic levels collectively form the ecological pyramid.
• Food Chains and Webs:*
• The transfer of energy from plants to animals is a fundamental aspect of nature.
• The 'detritus' food chain involves organisms that feed on dead organic matter.