Ecology
The study of how organisms interact with each other and their environment.
🌍 Ecosystems
An ecosystem includes all the living organisms in an area plus the non-living components (soil, water, air, sunlight). Energy flows from producers (plants) to primary consumers (herbivores) to secondary consumers (carnivores), losing about 90% at each level.
🕸️ Food Webs
More realistic than simple food chains, food webs show the complex feeding relationships in an ecosystem. Keystone species have disproportionate effects: removing wolves from Yellowstone changed river courses by altering elk grazing behavior (trophic cascade).
🌱 Biogeochemical Cycles
Nutrients cycle through ecosystems. The carbon cycle moves carbon between atmosphere, oceans, and living things. The nitrogen cycle converts atmospheric nitrogen into forms usable by plants. Human activity has significantly disrupted both cycles.
🦋 Biodiversity
Earth has an estimated 8.7 million species (only 1.3 million described). Tropical rainforests contain about 50% of species on 7% of land. We are currently in the sixth mass extinction, with species disappearing 100-1,000x faster than the background rate due to habitat loss and climate change.
☢️ Radiation Ecology
The Chernobyl Exclusion Zone, despite high radiation levels, has become an unexpected wildlife refuge. Without human activity, populations of wolves, lynx, bears, and wild horses have rebounded. Studies show complex effects: some animals show DNA damage, others appear unaffected.
🌡️ Climate and Ecology
Climate change is shifting species ranges poleward and to higher altitudes. Phenological mismatches occur when species that evolved together (flowers and pollinators) change their timing at different rates. Ocean acidification from CO2 threatens coral reefs and shellfish.