Ecology and Sustainability
Core concepts
Ecology studies interactions between organisms and their environment. Populations are groups of one species; communities include multiple species; ecosystems add abiotic factors. Producers make energy, consumers eat, and decomposers recycle nutrients. Food chains and webs show energy flow; only about 10% passes to the next trophic level. Carrying capacity limits population growth; predator-prey cycles show feedback. Biodiversity supports resilience. Sustainability means meeting present needs without compromising future generations. Human impacts include habitat loss, pollution, invasive species, and climate change. Bioaccumulation concentrates toxins up food chains.
Traps to watch
- Confusing a food chain with a food web.
- Assuming energy cycles; matter cycles, but energy flows and is lost as heat.
- Thinking a population can grow indefinitely.
- Treating an introduced species as always harmless.
- Ignoring abiotic factors in ecosystem questions.
Worked example
If producers have 10,000 J, primary consumers receive about 1,000 J, secondary consumers about 100 J, and tertiary consumers about 10 J. This explains why top predators are fewer and why toxins can concentrate at higher levels.
Rule of thumb
Energy decreases up each trophic level; matter cycles. Identify the trophic level before calculating energy transfer.