1. Ecosystems and their Components
Chapter 3

2. 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)

4. Atmosphere thin 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 miles above earth’s surface
contains ozone to help filter out UV radiation (98%); “global sunscreen”

5. Hydrosphere all 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)

6. Geosphere
Layers 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

7. 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

8. Energy in Ecosystems Ecosystems 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

9. 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

10. Trophic levels and feeding relationships
Producers
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)

11. Cellular Respiration
producers, 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

12. 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

13. 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)

14. 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

15. 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.

16. Importance of Ecosystems