Ecosystem – Composition, Structure, Function & Productivity YouTube Lecture Handouts

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Watch video lecture on YouTube: Ecosystem - Biotic & Abiotic (Components), 3 Types & 2 Functions Ecosystem - Biotic & Abiotic (Components), 3 Types & 2 Functions
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Ecosystem

  • Self-regulated & self-sustaining

  • Structural and Functional unit of nature includes living beings and environment

  • Interact and exchange material

  • Open System – input of energy and matter

  • Result in productivity

Types of Ecosystem

Homeostasis/Biological Equilibrium

Functional balance which is not static and fluctuates within limits

Controls

  • Carrying Capacity

  • Recycling Waste

  • Self-Regulation

  • Feedback System

📝 Components of Ecosystem

👌 Biotic – food contains energy for body building, growth and functions

  • Producers (Autotrophs)

  • Consumers (Heterotrophs)

  • Decomposers (Reducers)

Abiotic – non-living factors

  • Temperature

  • Light

  • Wind

  • Humidity – epiphytes that grow

  • Precipitation

  • Water – xerophytes & hydrophytes

  • Background – Chameleon (change color); praying mantis & frog are green

  • Gases

  • Soil – water retention, aeration & minerals

  • pH – acidic (Euglena & flagellates) or basic (calcareous shells)

  • Relief – north & south faces of hill

  • Mineral Elements

Structure

  • Species Composition – identify and enumerate plants and animals

  • Stratification – vertical layers

  • Trophic Levels

  • 👌 Standing Crop – living biomass in unit area (dry weight is preferred as is independent of moisture differences)

  • 👌 Standing State – inorganic nutrients in ecosystem (non-living)

📝 Ecosystem Functions

  • Productivity

  • Decomposition

  • Energy Flow

  • Nutrient Cycling

Image of pond ecosystem

Image of Pond Ecosystem

Image of pond ecosystem

Productivity

  • Rate of synthesis of energy containing biomass by any trophic level per unit area in unit time

  • Measured as

  • Measured as

  • 👌 Primary Productivity – energy accumulation in green plants per unit area over time

  • Secondary Productivity – Rate of re-synthesis of material by consumers

  • Respiration loss is 20% for autotrophs, 30% for herbivores and 60% for carnivores

  • Maximum productivity – tropical rainforest

  • Minimum productivity – desert or Arctic regions

  • Order of productivity:

  • Tropical Rainforest > Tropical Deciduous > Temperate Deciduous > Temperate Coniferous > Savannah > Temperate Grassland > Scrub

Factors Affecting Productivity

  • Solar radiation - maximum in tropics and so photosynthesis and NPP highest in tropics

  • Temperature – temperate forest have lesser productivity due to cold climate

  • Moisture

  • Nutrients

  • Photosynthetic Efficiency

Decomposition

Detritus

  • Above Ground – litter (plant driven), dried plants

  • Below Ground – dead roots, underground dead animals

👌 Process

  • Fragmentation of Detritus (earthworm as farmer’s friends)

  • Catabolism

  • Leaching – soluble substances are subject to leaching

👌 Products formed

  • Humus by humification – humus is dark colored organically rich in lignin and cellulose

  • Inorganic nutrients by mineralization – both non mineral ( ) & mineral ( ) from organic matter

Factors Affecting Decomposition

  • Temperature

  • Moisture – excess moisture impedes decomposition due to anaerobiosis

  • pH – alkaline soils are rich in detrivores and acidic nature decreases detrivores

  • Composition – chitin and lignin are slow to decompose

  • Aerobiosis – aerobic conditions are required