Lecture Notes: Ecosystems and Ecology (ESS Series Episode 2)

Overview

• Focus on ecosystems and ecology, applying theoretical frameworks to practical examples.
• Introduction to components of ecosystems, their interactions, and governing laws.

Key Concepts

• Abiotic vs. Biotic Factors:
  • Abiotic Factors: Non-living factors (e.g., temperature, sunlight, pH).
  • Biotic Factors: Living factors (e.g., predation, herbivory, parasitism).
• Limiting Factors:
  • Affect population size and growth.
  • Split into density-dependent (competition, predation, disease) and density-independent factors (weather extremes, natural disasters).
• Carrying Capacity:
  • Maximum number of organisms an environment can sustainably support.
  • Population growth approaches this as resources become limited.

Population Growth Curves

• J Curve: Exponential growth with abundant resources.
• S Curve: Logistic growth; population stabilizes at carrying capacity due to limiting factors.

Energy Flow in Ecosystems

• Food Chains and Webs:
  • Food Chain: Linear sequence of organisms, each feeding on the previous.
  • Trophic Level: Position in a food chain.
  • Food Web: Complex network of interrelated food chains.

Important Ecosystem Players

• Producers (Autotrophs): Convert atmospheric carbon to organic form.
• Consumers (Heterotrophs): Eat other organisms.
• Decomposers: Break down dead organic matter, recycle nutrients.

Ecosystem Processes

• Succession:
  • Describes temporal changes in ecosystem following disturbances (e.g., forest fire recovery).
• Zonation:
  • Describes spatial changes across an ecosystem (e.g., variation in species across a shoreline).

Key Definitions

• Species: Organisms that can interbreed and produce fertile offspring.
• Population: Group of organisms of the same species in a particular area.
• Community: Different populations living in the same area.
• Habitat: Natural environment where a species lives.
• Niche: Role of an organism within its ecosystem.