Ecology Biosphere

What is ecology? Biosphere The study of interactions that take place between organisms and their environment Biosphere The portion of earth that supports living things Extends from high in the atmosphere to the bottom of oceans

Biotic vs abiotic Non living environment – abiotic factors The non living parts of an organism’s environment are abiotic Ex- air currents, temp, moisture, light, and soil Living environment- biotic factors All the living organisms that inhabit an environment are biotic factors All organisms depend on others directly or indirectly for food, shelter, reproduction, or protection Biotic vs abiotic

Levels of organization Organism Population- all members of one species in an area Community- all populations in a given area Ecosystem- community + abiotic factors Biome- ecosystems with similar climate and communities Biosphere- abiotic + biotic factors of the entire earth Levels of organization

Energy flow All organisms need energy for life activities Energy comes from food, and ultimately the sun Consumption of food is an energy transfer Energy flow

autotrophs Ultimate source of energy for life is the sun An organism that uses light energy or energy stored in chemical compounds to make energy for itself is a producer, or autotroph Plants use the sun’s light energy to make food in photosynthesis Chemoautotrophs use chemical energy to produce food instead of light Ex- certain bacteria autotrophs

An organism that cannot make its own food and feed on others A heterotroph that only feeds only plants is a herbivore Heterotrophs that eat both plants and animals are omnivores Detritivores eat dead plants and animals (detritus) Some organisms such as bacteria and fungi are decomposers breaking down complex compounds of dead and decaying organisms that can be more easily absorbed Heterotrophs

Flow of matter and energy A food chain is a simple model used to show how matter and energy move through an ecosystem Nutrients and energy move from autotrophs to heterotrophs, and eventually to decomposers A food chain is drawn using arrows to indicate the direction in which energy is transferred from one organism to the next The amount of energy remaining in the final transfer is only a portion of what was available at the first transfer, 10% Most of the energy is given off as heat at each transfer, 90% Flow of matter and energy

Each organism in a food chain represents a feeding step or trophic level, in the passage of energy and materials Producers convert solar energy into organic compounds Primary consumers eat producers Secondary consumers eat primary consumers Tertiary consumers eat secondary consumers A food chain represents only one possible route for the transfer of matter and energy Food webs show all possible feeding relationships at each trophic level Trophic levels

An ecological pyramid shows the amount of energy or matter an ecosystem contains at each level The base represents the producers, at the first trophic level Higher levels are layered on top 3 different pyramids exist: energy, biomass, and numbers Ecological pyramids

The amount of available energy decreases at each succeeding trophic level The total energy transfer from one trophic level to the next is only 10% because Organisms fail to capture and eat all the food energy available Organisms use much of the energy for life processes Energy gets released as heat Energy pyramid

The total mass of living matter at each trophic level Biomass Pyramid

Shows that population numbers decrease at each higher trophic level Numbers pyramid

Cycles in nature Hydrologic Cycle 1. Precipitation- water vapor condensing 2. Evaporation- liquid water changing to gad 3. Transpiration- water evaporating from leaves Water is constantly moving between the atmosphere and earth, driven by the heat from the sun Cycles in nature

Cycles in nature Carbon Cycle Carbon and oxygen combine to form CO2 Plants use CO2 during photosynthesis to produce sugars Plants use sugars for growth and cellular respiration Herbivores eat plants, and incorporate sugar into their structures and for cell respiration Cell respiration breaks down sugar releasing CO2 and water back into the atmosphere Cycles in nature

CO2 is added to the atmosphere by cellular respiration, volcanic action, and burning fossil fuels It’s removed by plants Green house gases, like ozone, impede the escape of heat from earth’s surface This can lead to global warming or the long-term increase in temperature of the earth’s lower atmosphere Photosynthesis: sunlight + 6 H2O  C6H12O6 + 6 O2 Respiration: C6H12O6 + 6 O2  ~34ATP + 6 H2O Cycles in nature

Cycles in nature Nitrogen Cycle Relies heavily on bacteria Soil major reservoir 78% nitrogen Nitrogen found in proteins and DNA, RNA Plants need nitrogen in the form of nitrate NO3 Animals get nitrogen from proteins in food Cycles in nature

Cycles in nature Nitrogen Fixation- plants cannot use nitrogen gas Nitrogen fixing bacteria convert nitrogen gas into ammonia (NH3) and are found in the roots of legume plants Ammonia can be take up by plants Nitrification- nitrifying bacteria convert ammonia to nitrates and nitrites Denitrification- nitrogen often a limiting factor in ecosystems Nitrogen is lost from soils via leaching and runoff Denitrifying bacteria convert nitrates and nitrites into nitrogen gas Cycles in nature

Cycles in nature Phosphorous Cycle Phosphorous moves between the living and nonliving parts of the environment Main abiotic reservoir for phosphorous is rock Weathering of rock adds phosphorous to soil Plants absorb phosphates from soil and build organic compounds (ATP, DNA) Animals eat plants and incorporate phosphorous into compounds Cycles in nature

Nutrient limitation Primary Productivity The amount of light energy converted to usable energy by autotrophs Gross vs. Net primary productivity GPP- amount of light energy converted to chemical energy by photosynthesis per unit time NPP- GPP minus the energy used by primary producers for cellular respiration GPP-R = NPP What limits primary production? Aquatic ecosystems- light, nitrogen, phosphorous Terrestrial – temperature, moisture, minerals (potassium) Nutrient limitation