Ecosystem Structure

An ecosystem is community (living) plus abiotic (light, water, T, soil, pH). Habitat: address. Niche: job (what it eats, when, where). Population: one species in an area. Community: all species there. Biosphere: all ecosystems. Producers (autotrophs), consumers, decomposers. A pond, a forest, a crop field are exam ecosystems. Ecosystems are functional units of community plus environment. Energy flows one way; nutrients cycle. Producers capture energy; decomposers return minerals to the soil. A niche describes an organism role; a habitat describes where it lives.

ECOSYSTEM STRUCTURE is an independent FBISE learning unit because students must connect its structures and processes with their biological functions and examples.

ABIOTIC: Light limits photosynthesis. Water. Temperature enzymes. Soil ions. Wind. Salinity in a shore. These set who can live. Light intensity and quality affect photosynthesis rate. Temperature affects enzyme activity. Water availability limits distribution. Soil pH affects mineral uptake. Wind increases transpiration. Examples: Desert: water short; Deep sea: light short; pH of soil. BIOTIC: Competition, predation, mutualism, parasitism named. Decomposers close the cycle. Niche overlap -> compete. Two species, same niche: exclusion idea (Gause named if the book). Competition (same or different species). Predation controls population. Mutualism benefits both (bee + flower). Parasitism: one benefits, one harmed. Decomposers essential for nutrient cycling. Examples: Producer first; Decomposer always; Niche not just 'home'. Exam: habitat vs niche. Habitat is where. Niche is how it lives there (food, time, role). Two species can share a habitat with different niches.