Lecture Ecology F Chapter 54 ~ Ecosystems and the Biosphere F Chapter 55 ~ Ecology and the Geography of Life

Relationships, I F Trophic structure / levels ~ feeding relationships in an ecosystem F Primary producers ~ the trophic level that supports all others; autotrophs F Primary consumers ~ herbivores F Secondary and tertiary consumers ~ carnivores F Detrivores/detritus ~ special consumers that derive nutrition from non-living organic matter F Food chain ~ trophic level food pathway

Relationships, II F Food webs ~ interconnected feeding relationship in an ecosystem

Energy Flow, I F Primary productivity (amount of light energy converted to chemical energy by autotrophs) Gross (GPP): total energy Net (NPP): represents the storage of energy available to consumers Rs: respiration F NPP = GPP - Rs F Biomass: primary productivity reflected as dry weight of organic material F Secondary productivity: the rate at which an ecosystem's consumers convert chemical energy of the food they eat into their own new biomass

Energy Flow, II F Ecological efficiency : % of E transferred from one trophic level to the next (5-20%) F Pyramid of productivity : multiplicative loss of energy in trophic levels F Biomass pyramid : trophic representation of biomass in ecosystems F Pyramid of numbers : trophic representation of the number of organisms in an ecosystem

Chemical Cycling F Biogeochemical cycles: the various nutrient circuits, which involve both abiotic and biotic components of an ecosystem F Water – Water moves among ocean, land and atmosphere in the hydrologic cycle F Carbon – Carbon dioxide is the pivotal molecule in this cycle F Nitrogen – Bacteria are essential to this cycle F Phosphorus – This cycle lacks a gaseous component

Human Impact F Biological magnification : trophic process in which retained substances become more concentrated at higher levels F Greenhouse effect : warming of planet due to atmospheric accumulation of carbon dioxide and other gases F Ozone depletion : effect of chlorofluorocarbons (CFC’s) released into the atmosphere F Rainforest destruction F Cause: Overpopulation?

Abiotic factors F Biosphere ~the sum of all the planet’s ecosystems F Biome~ areas of predominant flora and fauna F Temperature F Water F Sunlight F Wind F Rocks & Soil F Periodic disturbances Ecotone: biome grading areas

Global climate F Seasons Precipitation & Winds

Aquatic biomes F Vertical stratification: F photic zone~ photosynthetic light F aphotic zone~ little light thermocline~ narrow stratum of rapid temperature change F benthic zone~ bottom substrate F Organisms –Phytoplankton ~ community of small free-floating producers –Zooplankton ~ community of small free-floating consumers –Nekton ~ community of larger free- floating consumers –Benthos ~ community of bottom- dwelling organisms F Detritus ~ dead organic matter; food for benthic organisms

Freshwater biomes F Littoral zone~ shallow, well- lit waters close to shore F Limnetic zone~ well-lit, open water farther from shore F Profundal zone~ deep, aphotic waters F Lake classification: oligotrophic ~ deep, nutrient poor eutrophic ~ shallow, high nutrient content mesotrophic ~ moderate productivity F Wetland ~ area covered with water F Estuary ~ area where freshwater merges with ocean

Lake stratification & turnover F Thermal stratification~ vertical temperature layering F Biannual mixing~ spring and summer F Turnover~ changing water temperature profiles; brings oxygenated water from the surface to the bottom and nutrient rich water form the bottom to the surface

Marine biomes F Intertidal zone ~ area where land meets water F Neritic zone ~ shallow regions over continental shelves F Oceanic zone ~ very deep water past the continental shelves F Pelagic zone ~ open water of any depth F Benthic zone ~ seafloor bottom F Abyssal zone ~ benthic region in deep oceans

Terrestrial biomes F Tropical forests~ equator; most complex; constant temperature and rainfall; canopy; dry and wet F Savanna~ tropical grassland with scattered trees; occasional fire and drought; large herbivores F Desert~ sparse rainfall (arid) (<30cm/yr) F Chaparral~ spiny evergreens at midlatitudes along coasts F Temperate grassland~ all grasses; seasonal drought, occasional fires; large mammals F Temperate deciduous forest~ midlatitude regions; broad-leaf deciduous trees F Coniferous forest~ cone-bearing trees F Tundra~ permafrost; very little precipitation