Carbon cycle – human impact?
Human: Burning fossil fuels ↑ CO₂
Natural process: Photosynthesis (plants absorb CO₂), respiration, decomposition
Impact: Global warming, ocean acidification → habitat loss, temperature-sensitive species die
Nitrogen cycle – human impact?
Human: Fertiliser runoff ↑ reactive nitrogen
Natural process: Fixation → nitrification → assimilation → denitrification
Impact: Eutrophication → algal blooms → oxygen depletion → aquatic species die
Phosphorus cycle – human impact?
Human: Fertiliser/mining ↑ phosphate
Natural process: Weathering of rocks → uptake by plants → consumed by animals → decomposition → sedimentation
Impact: Runoff → eutrophication → dead zones → species die
How do humans disrupt ecological succession?
Disturbance removes vegetation or alters conditions → slows or resets succession → favours invasive/opportunistic species
How do microbes help nutrient cycling?
Break down dead matter → release N, P, C; some fix atmospheric nitrogen → plants can use → supports ecosystem growth.
