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Ecology Basics 6 major terrestrial biomes • TRF • Desert • Tundra • Deciduous Forest • Coniferous Forest • Grasslands • Elevation • Precipitation • Substrate Aquatic biomes • Biomes that occur in the water differ from terrestrial biomes. • The major distinction in aquatic (water) biomes is whether or not the biome is comprised of salt or fresh water. • Therefore the 2 main aquatic biomes are fresh water biomes and marine biomes.(Salt containing) Special Aquatic Biomes • Estuaries are special aquatic biomes as they occur any where freshwater meets saltwater. • Does Arizona have any estuaries? Marine Zones are based on 2 main traits. • Depth (which impacts) – Light – Pressure – Temperature • Contact with coast (which impacts habitat) Specific Marine Sub-zones A)Intertidal/Neretic – highly photic has contact with coast B) Open Sea/Oceanic – photic but no contact with the coast C) Open Sea/Pelagic - non-photic no contact with land D) Deep sea/Benthic - non-photic, cold temps and high pressure Clean up crew! • Detritivores- (Detritus feeders) aka scavengers-EX: – Larger –will be regulated on energy pyramid (as secondary consumer) because of size. • Decomposers- EX: – Smaller-does not get regulated on energy pyramid because of size. • BOTH heterotrophs that feed on nonliving organic matter….. Ecological Population Dynamics Biotic potential • The maximum number of offspring an organism can produce is its biotic potential. • What keeps organisms from reaching their full biotic potential? • Environmental limits (not enough food, water, shelter or things like disease, predation). These limits are called environmental resistance. Population Growth Models Exponential model • idealized • Called “r populations” (J-curve) Logistic model • realized • Called “K populations” (S-curve) Which one happens most often? Why? Strategies to increase biotic potential • r-selected • • • • • (opportunistic) Short maturation & lifespan Many (smaller) offspring No/little parental care High death rate EX:? • K-selected (equilibrial) • Long maturation & lifespan • Few (larger)offspring; • Extensive parental care • Low death rate • EX:? Population limiting factorsEnvironmental resistance! • Density-dependent factors: • limited food water, shelter •predation • disease • Density-independent factors •weather/climate • These factors lead to K* • (*K=The max number of individuals an area can sustain/Carrying capacity) • Biotic potential vs Environmental resistance! (All life must deal with this) • Leads to adaptation Chemical Cycling Chemical Cycling Biogeochemical cycles: the various nutrient circuits, which involve both abiotic and biotic components of an ecosystem • • • • Water Carbon Nitrogen Phosphorous . Nitrogen Cycle • Nitrogen enters the atmosphere, in gaseous form N2. It has to be transformed into a usable form for organisms to use. • Nitrogen fixing bacteria convert N2 into NH4 in a process called nitrogen fixation. • NH4 is also produced by decomposers when breaking down organic matter in a process called ammonification. • Different bacteria take NH4 and covert it into nitrite (NO2-) and nitrate (NO3-) in a process called nitrification. (This allows producers to use the nitrogen now, assimilation) • Denitrifying bacteria convert nitrate (NO3-) back to N2 for release back into the atmosphere. Phosphorous Key Terms Leaching Weathering Runoff Chemical Precipitation Sedimentation Are ecosystems static or dynamic? Big Changes in the system • Primary succession- going from nothing (no soil)to pioneering community to climax community. • Why would there be nothing??? – Melting glaciers – Volcanic eruptions – Landslides – Strip mines • Secondary Succession - Re-establish an ecosystem after a disturbance • What could be a possible disturbance? – Flood – Fire