ABIOTIC FACTORS Of Ecosystems

*ABIOTIC FACTORS: physical aspects of the environment *can limit the size of a population *include: water, carbon, nitrogen, soil, light, and temperature

1. WATER: *Why important? *necessary for survival (i.e. metabolism), cells contain 70% - 90% water, acts as home to organisms

*also returns to air b/c animals breathe out water vapor/ urinate *takes place between Earth and atmosphere *water falls to Earth—plants pull water from ground *plants lose water through leaves (water back to air) (TRANSPIRATION) *also returns to air b/c animals breathe out water vapor/ urinate *also returns to air due to evaporation

= water changes from gas to liquid = rain falls to Earth =plants lose water through leaves =water changes from liquid to gas = water filters through soil– ground water

2. CARBON: *all living organisms need carbon *starts w/ autotrophs—photosynthesis—converts CO2 into usable energy (C- based) (takes C out of atmosphere) *Heterotrophs feed on autotrophs—growth and energy *as heterotrophs use C (energy), release CO2 back into air (respiration) *decomposers release CO2 back into atmosphere when they break down organic compounds *burning of fossil fuels also releases C back to atmosphere *how fast the cycle goes depends on whether C found in soil, leaves, roots, oil, fossils, etc.

*120 billion tons of C exchanged each year

3. NITROGEN *78% of air = Nitrogen *bacteria change N to usable form for plants (takes place in soil) *plants use N to make proteins—animals eat plants and make other proteins *urination by animals—contains excess N—returns to soil *also returns to soil when animals decay—plants can then reobtain N *Soil bacteria also act on dead—puts N back into the atmosphere

NITROGEN FIXATION: process of converting N gas to *NITROGEN FIXATION: process of converting N gas to nitrates (plants can use) *NITROGEN FIXING BACTERIA: convert N gas to ammonia, then nitrite, then nitrate *AMMONIFICATION: decomposers break down dead/ wastes and release N as ammonia *NITRIFICATION: bacteria in soil take up ammonia and oxidize it into nitrites (NO2-) & nitrates (NO3-) *DENITRIFICATION: anaerobic bacteria break down nitrates and release N gas into atmosphere

OTHER ABIOTIC FACTORS: 4. SOIL: *source of water/ minerals for plants *home to microorganisms *HUMUS: decayed remains of organisms that enrich soil *pH and type affects which plants grow

5. LIGHT: *source of energy for ecosystems *amount affects type of plants/ location of plants *also important for vision, migration patterns, vitamin production *heat produced by absorption of light contributes to water cycle

6. TEMPERATURE: *wind, amount of rainfall affect this *temperature decreases from surface upward and as move away from equator *varies with time (of day, of year) *air temperature varies more than water temperature *signals certain biological processes to start (i.e. blooming, migration) *organisms have adaptations for changes in temperature (i.e. perspiration)