Ecosystem components — A/L Biology

What must I remember about Ecosystem components?

• An ecosystem is a dynamic functional community comprising living biotic components interacting with their physical abiotic environment through energy flow and chemical nutrient cycling.
• Abiotic components include climatic factors (solar radiation, temperature, rainfall, wind, humidity) and edaphic factors (soil pH, texture, mineral composition, water retention capacity, topography).
• Biotic components are organized into trophic levels: Primary Producers (autotrophs: photoautotrophs fixing solar energy, chemoautotrophs), Consumers (heterotrophs: primary herbivores, secondary/tertiary carnivores, omnivores), and Decomposers / Saprotrophs (fungi, heterotrophic bacteria breaking down dead organic detritus).
• Ecological Niche vs Habitat: Habitat is the specific physical geographical location where an organism resides ('address'); Ecological Niche encompasses the organism's full functional role, resource utilization, and interactions in the ecosystem ('profession').
• Fundamental vs Realized Niche: Fundamental niche represents the total theoretical range of environmental conditions and resources an organism could utilize in the absence of biotic competition; Realized niche is the actual restricted portion occupied due to interspecific competition and predation.

Test yourself (1 minute)

1. Competitive Exclusion Principle (Gause's Law)

   Two competing species with identical ecological niches cannot coexist indefinitely on the same limiting resources; the more efficient competitor eventually eliminates the other, leading to niche differentiation (resource partitioning).

2. Resource Partitioning mechanism

   Sympatric species diverge morphologically or behaviorally to exploit different resources or microhabitats (e.g., Anolis lizards foraging at different tree heights, warblers feeding on different tree canopy zones).

3. Keystone Species concept

   A species having a disproportionately large impact on its community structure relative to its abundance (e.g., Pisaster sea star controlling mussel monocultures, top carnivores preventing herbivore overgrazing).

Practise Ecosystem components questions today

Source: NIE G.C.E. (A/L) Biology Syllabus & Resource Book, Unit 6

What comes next?

Next in the syllabus

Where does Ecosystem components fit in the syllabus?

Year 2 · Term 2