Ecosystems and their Ecosystems and their ComponentsComponents

Chapter 3Chapter 3

Ecosystem Components

The Earth is divided into four components that all interact together.

atmosphere (air)

hydrosphere (water)

geosphere (rock, soil and sediment)

biosphere (living things)

www.sws.uiuc.edu/nitro/biggraph.asp

Atmospherethin layer of gases surrounding earths surface.

layers of the atmosphere include:

troposphere

extends 11 miles above sea level at equator and 4 miles above sea level at poles.

contains all air we breathe, including nitrogen (78%), oxygen (21%), and greenhouse gases (natural greenhouse effect)

where all weather occurs

stratosphere

next layer, extends 11-31 miles above earth’s surface

contains ozone to help filter out UV radiation (98%); “global sunscreen”

Hydrosphereall water at or near the earth’s surface

founds as water vapor, liquid water, ice and frozen in permafrost

97% of the earths water is found in the ocean (cover 71% of earth’s surface)

GeosphereLayers of soil, rock and sediment at the earths surface and in layers below.

core: hot, molten inner layer, mostly iron

mantle: thick rock middle layer made of silicon, iron, oxygen and magnesium

crust: outermost layer, contains all nonrenewable fossil fuels and minerals, as well as renewable soil nutrients and organisms

Biosphere

Parts of atmosphere, hydrosphere and geosphere where all living components are found

Ecology: study of interactions between organisms and their environment

biotic and abiotic components

Energy in EcosystemsEcosystems are driven by

1. interactions between organisms

2. the flow of high-quality energy (sun)

most energy is absorbed or reflected back into space by the atmosphere

goes to generating winds (1%)

plants, algae and bacteria use to produce nutrients (.1%)

natural greenhouse effect (warms earth to sustain life)

3. cycling of nutrients

Within an Ecosystem...

Interactions happen between organisms, populations, and communities

includes both biotic and abiotic components

all organisms organized into trophic levels depending on source of food or nutrients

Trophic levels and feeding relationshipsProducers

autotrophs. use photosynthesis (water + carbon dioxide + light ---> oxygen and glucose)

includes plants, algae, phytoplankton and some bacteria (chemosynthesis)

Consumers

heterotrophs. obtain energy by feeding on other organisms.

primary consumers, secondary consumers, tertiary consumers.

herbivores, omnivores and carnivores.

Decomposers

consumers that release nutrients from the wastes of plants and animals and return those nutrients to the soil, air or water for reuse.

mostly bacteria and fungi.

detritivores: feed on the wastes and dead bodies of other organisms and break into smaller particles (detritus)

earthworms and insects; vultures (scavengers)

Cellular Respirationproducers, consumers, and decomposers within their cells use chemical energy to fuel their life processes

aerobic respiration

glucose + oxygen ---> carbon dioxide + water + energy

opposite of photosynthesis

anaerobic respiration

occurs in the absence of oxygen (fermentation)

end products include methane, ethyl alcohol, acetic acid or hydrogen sulfide

Energy Cycling

Illustrated through food chains and food webs

describes the flow of energy from one trophic level to another

photosynthesis, feeding, and decomposition

some energy lost to the environment as heat through these processes

biomass: weight of all organic matter contain it its organisms

chemical energy in biomass is transferred from one trophic level to another

energy is lost with each transfer, less is available to the next trophic level

general rule is only 10% of available energy is passed between trophic levels, the rest is lost (ecological efficiency)

explains why there are rarely more than 4-5 trophic levels (not enough energy to support), and why more organisms are found in lower trophic levels (fewer top carnivores)

biomass found in each ecosystem is determined by how much solar energy the producers can capture and store.

varies greatly depending on the ecosystem

gross primary productivity (GPP): rate at which an ecosystem’s producers convert solar energy into chemical energy; total amount of energy captured by producers

net primary productivity (NPP): rate at which producers use photosynthesis to produce and store chemical energy minus the rate at which they use some of this stored chemical energy through aerobic respiration

this ultimately limits the number of consumers that can survive on earth

more productivity = more organisms supported

highest in estuaries and rainforests

Cycling of Matter in Ecosystems

the elements and compounds that make up nutrients move continually through air, water, soil, rock, and living organisms.

This is illustrated through five biogeochemical (nutrient cycles)

water, carbon, phosphorus, nitrogen and sulfur cycles.

Importance of Ecosystems