2.2.20—Human activity impacts

Human actions change where energy is used and where matter is stored, moved or lost from ecosystems.

Harvest removes biomass, dams redirect water and burning transfers stored chemical energy to heat and gases. Track the pathway rather than labelling an action simply good or bad.

Fertiliser can raise crop production, but runoff moves nitrogen to a lake and can increase algal growth and oxygen demand.

Both: nitrogen moved into the lake, while extra algal growth changed energy flow and respiration.

Matter is not destroyed by harvesting; it is relocated, transformed or exported from the system.

Burning fossil fuels raises carbon dioxide but warming and co-pollutants can reduce primary productivity; deforestation removes producer biomass and transpiration; urbanization replaces productive habitat and fragments food webs; agriculture redirects production into harvest and can export nutrients through runoff. For each activity, trace the changed storage or flow, its effect on photosynthetic capacity or trophic links, and any displaced impact rather than assuming one universal outcome.