Nitrogen fixation - bacteria fix N 2 with hydrogen to become ammonia Nitrification - bacteria convert most of the ammonia in soil to nitrite ions (NO 2 - ) and nitrate ions (NO 3 - ) Assimilation - plants absorb ions Ammonification - decomposers releasing nitrogen in form of ammonium (NH 4 + ) Denitrification - “unfixing” nitrogen back into free nitrogen
WHAT IS THE EL NINO-SOUTHERN OSCILLATION (ENSO)?
Normal Conditions Cold water Warm water Thermocline SOUTH AMERICA Warm waters pushed westward AUSTRALIA EQUATOR Surface winds blow westward
El Niño Conditions Cold water Thermocline Warm water Warm water deepens off South America SOUTH AMERICA Warm water flow stopped or reversed AUSTRALIA EQUATOR Drought in Australia and Southeast Asia Winds weaken, causing updrafts and storms
the greenhouse effect 1)Water vapor H 2 O 2)Carbon dioxide CO 2 3)Methane CH 4 4)Nitrous oxide N 2 O 5)Chlorofluorocarbons CFCs Major Greenhouse Gases
a Winds carry moisture inland from Pacific Ocean b Clouds, rain on windward side of mountain range c Rain shadow on leeward side of mountain range Moist habitats Dry habitats the rain shadow effect
Ages 0-14 Ages 15-44 Ages 45-85+ Rapid Growth Guatemala Nigeria Saudi Arabia Rapid Growth Guatemala Nigeria Saudi Arabia Slow Growth United States Australia Canada Slow Growth United States Australia Canada Male Female Zero Growth Spain Austria Greece Zero Growth Spain Austria Greece Negative Growth Germany Bulgaria Sweden Negative Growth Germany Bulgaria Sweden
Food webs and energy flow Water regulation Influence local-regional climate Numerous habitats and niches Air purification Carbon sequestration