The Biosphere Chapter 3

What is Ecology?  scientific study of interactions among organisms and between organisms and their environment

Biosphere  Combined portions of the planet in which all of life exists, including land, water and air or atmosphere  Extends from 8 kilometers above Earth’s surface to 11 kilometers below the surface of the ocean

Interactions and Interdependence  Interactions within the biosphere produce a web of interdependence between organisms and the environment in which they live

Levels of Organization  Individual: interactions between an organism and its surroundings  cottontail rabbit  Population: groups of individuals that belong to the same species and live in the same area  group of cottontail rabbits

Levels of Organization  Communities: different populations that live together in a defined area  rabbits, coyotes, ravens, lizard  Ecosystem: collection of all the organisms that live in a particular place, together with their nonliving, or physical, environment  rabbits, coyotes, ravens, lizard, rocks, dirt, climate, water

Levels of Organization  Biome: group of ecosystems that have the same climate and dominant communities  desert, tundra, tropical rain forest  Biosphere: planet Earth

Ecological Methods  Three approaches to ecological research:  Observing: Use of 5 senses to ask ecological questions  Experimenting: Used to test hypotheses  artificial environment in a lab  within natural ecosystems

Ecological Methods  Modeling: Used to gain insight into complex phenomena such as the effects of global warming  may include mathematical formulas based on data collected through observation and experimentation  predictions tested by further observations and experiments

Energy Flow  Energy flows from the sun or inorganic compounds to producers.  Consumers eat producers to get energy.  The primary source of energy on Earth is the sun!!

Producers  Autotrophs – “self feed”  Use sunlight to create carbohydrates via photosynthesis  Ex – Plants, algae and some bacteria  Some bacteria create organic compounds from inorganic chemicals – Chemosynthesis  Live in remote places.

Producers

Consumers  Heterotroph – “Different food”  Must eat to obtain energy.  Ex – animals, fungi, some protists

Types of Heterotrophs  Herbivore – eats plants  Carnivore – eats animals  Omnivore – eats plants and animals  Detritivore – eats detritus (plant and animal remains)  Ex- snails, crabs, earthworms  Decomposer – breaks down organic matter  Ex – bacteria and fungi

Feeding Relationships  Energy flows through an ecosystem in one direction,  from the sun or inorganic compounds  autotrophs (producers)  various heterotrophs (consumers).

Food Chain  A series of steps in which organisms transfer energy by eating and being eaten.  i.e. Wheat  mouse  snake  hawk

Food Chain Example

Food Web  Network of complex interactions formed by the feeding relationship among the various organisms in an ecosystem.

Trophic Levels  Each step in a food chain or food web  1 st level = producers  2 nd, 3 rd, or higher levels = consumers  Usually no more than 5 levels because 90% of energy is lost at each level.

Ecological Pyramid  A diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web.  Energy, biomass, and population numbers can all be represented by a pyramid.

Ecological Pyramid

Cycles of Matter  Recycling in the Biosphere  Matter is recycled within and between ecosystems.  Matter moves through an ecosystem in biogeochemical cycles.

Water Cycle

Carbon Cycle

Nitrogen Cycle N 2 in Atmosphere NH 3 NO 3 - and NO 2 -

Nitrogen Cycle  78% of Earth’s atmosphere is Nitrogen gas = N 2  Nitrogen containing products:  Ammonia (NH 3 )  Nitrate ions (NO 3 -)  Nitrite ions (NO 2 -)  Nitrogen is needed for protein and nucleic acid synthesis

Nitrogen Cycle  Converting nitrogen gas into ammonia is called nitrogen fixation.  Only certain types of bacteria can do this.  Plants use the converted products (NH 3, NO 3 -,& NO 2 -) to make plant proteins.  Some bacteria convert nitrates into nitrogen gas (denitrification).

Phosphorus Cycle

 Phosphorus is important for the formation of DNA and RNA molecules.  Phosphorus is not very common and does not enter the atmosphere, instead it is found mostly on land in rock and soil.

Primary Productivity  The rate at which producers create organic matter.  Determines the size of the community.  Limited by availability of nutrients.  Land – phosphorus (P), nitrogen (N), potassium (K)  Marine – nitrogen  Fresh water - phosphorus

Algal Bloom