18.11 Ecosystems and Habitats

Overview

• Organisms live and interact in communities, forming complex networks of relationships within specific environments.
• These interactions, along with their environment, define ecosystems, which can vary greatly in size and complexity.

Key Definitions

1. Ecosystem:

• A relatively self-contained system comprising:
  • A community of organisms (living organisms of all species in the area).
  • The environment (physical and chemical factors) with which they interact.
• Includes biotic and abiotic components such as:
  • Living organisms: Plants, animals, fungi, microbes.
  • Physical environment: Soil, water, air, rocks.
  • Chemical factors: Nutrients, gases, pH.

1. Community:

• All the living organisms of all species found in a particular ecosystem at a particular time.

1. Habitat:

• The physical place where a species lives within an ecosystem (e.g., tree bark, water, soil).
• Provides the resources necessary for survival.

1. Niche:

• The role or function of an organism within an ecosystem.
• Includes:
  • Physical location (e.g., where it lives).
  • Energy source (e.g., feeding behavior).
  • Interactions with other species (e.g., predators, competitors) and the environment.
• Complex and specific, encompassing an organism’s behavior, diet, and survival strategies.

Features of Ecosystems

• Diversity:
  • Ecosystems range from simple (e.g., deserts) to complex (e.g., tropical rainforests, coral reefs).
  • Example:
    • A pond is a small ecosystem with distinct organisms compared to the surrounding soil or air.
    • The open ocean is a vast, interconnected ecosystem.
• Interconnectivity:
  • No ecosystem is fully isolated.
  • Examples:
    • Birds migrating between ecosystems.
    • Rivers linking terrestrial and aquatic ecosystems.

Examples

• Tropical Forests:
  • Highly diverse ecosystems like Costa Rica’s rainforests.
  • Epiphytes (plants growing on other plants) create habitats for smaller organisms, such as beetles.
  • One tropical tree can host up to 1200 beetle species.
• Great Egret:
  • Habitat: Freshwater ecosystems and nearby trees for nesting.
  • Niche: Includes feeding behaviors in water and roosting in trees.

Comparison: Ecosystem vs. Niche

Summary

• Ecosystems represent broad, interactive systems of organisms and their environment, while niches focus on the specific roles and behaviors of individual species within these systems.
• Organisms adapt to their habitats and perform unique functions in their niches, contributing to the complexity and sustainability of ecosystems.