Download Biological Production and Ecosystem Energy Flow

AP Environmental Chapter 9
Unit 2
Energy Flow
 Movement of energy through an ecosystem from
the environment, through organisms, and then
back to the environment
 Inputs:
 Energy fixed by organisms
 Energy transferred as heat through the air, water
or land currents
Energy Flow
 Kinetic energy in the environment can be visible as
heat in living organisms
 The infrared picture on
the right shows clover
leaves with and without
ozone exposure
st
1
Law of Thermodynamics
 “Conservation of Energy”
 States that in any change energy is neither created
or destroyed
nd
2
Law of Thermodynamics
 Whenever work is done some energy is always lost
to heat and cannot be efficiently recovered
 This decrease in order (disorganization of energy)
is called entropy
nd
2
Law of Thermodynamics
 For an ecosystem to function energy must
continuously be added to replace energy lost by
metabolic processes
Energy Efficiency
 As energy flows through a food web, it is degraded,
and less and less is useable.
 Energy efficiency- the ratio of output to input
 The amount of useful work obtained from some amount
of available energy
Energy Efficiency
 Trophic-level efficiency- the ratio of production of one
trophic level to the production of the next trophic
level.
 Never very high
 1-3% in natural ecosystems
 10% may be maximum
 90% of all energy lost as heat
Biological Productivity
 The goal of ecological communities is to efficiently
use energy for the production of biomass
(biological material)
 Energy is the ultimate
limiting factor for the
growth of a species or
population
Biological Productivity
 Biomass- the total amount of organic matter on
Earth or in any ecosystem or area.
 Usually measured as the amount per unit
surface area
 Biological production- the capture of usable
energy from the environment to produce organic
compounds in which that energy is stored.
Biological Productivity
 Change in biomass over a given time is called net
production.
 Three measures used for biological production
 Biomass
 Energy stored
 Carbon stored
Types of Production
 Autotrophs
 Make their own organic matter from energy
source and inorganic compounds
 Primary production
 Most photosynthesize, some chemoautotrophs
 Heterotrophs
 Cannot make their own organic compounds and
must feed on other living things
 Secondary production
Biological Productivity
• Primary production generates
the most biomass
• Secondary production stores
or uses biological energy
through processes like tissue
growth or respiration to create
smaller amounts of biomass
• In a food chain decomposers
carry out decomposition of
biomass into abiotic nutrients
Biological Productivity
 Use of energy from organic matter by both
heterotrophic and autotrophic organisms is done by
respiration.
 Organic matter (glucose) combines with oxygen
 Releases energy stored in chemical bonds along with
carbon dioxide and water
 Respiration- the use of biomass to release energy that
can be used to do work.
Gross and Net Production
 Production of biomass for use as energy
 1. An organism produces organic matter in its body.
(gross production)
 2. It uses some of this new organic matter as a fuel for
respiration.
 3. It stores some of the newly produced organic matter
for future use. (net production)
Gross and Net Production
 Gross Primary Production(GPP) is the total amount
of CO2 that is fixed by the plant in photosynthesis.
 Net Primary Production (NPP) = GPP – Respiration
 Net Ecosystem Production (NEP) =
GPP – Respiration from all sources in the ecosystem
Primary Production
 There are 2 ways to measure the primary production of
a biological community
 Rate of photosynthesis (measurement of CO2 depletion
or O2 production)
 Rate of increase in plant biomass (weight of organic
tissue)
What are the sources of errors in both methods for a
natural environment?
Biological Productivity
 Depending on the situation involved there are
different ways to measure productivity of a system
 Standing crop: measure of the biomass of a system at a
single point in time (Ex: the amount of corn growing
in a corn field)
 Energy output (Ex: machinery)
Biological Productivity
 Biomass can be gained through
ingestion of chemical energy
created by primary production
 Biomass is lost through excretion
(decomposition or respiration)
 Assimilation is the amount of
biomass created overall
 Assimilation = ingestion-excretion
Biological Productivity
 Different ecosystems reach different levels of
productivity based on environmental factors
Biological Productivity
 Worldwide production based on the area covered by
the ecosystem globally
Ecological Succession
 Ecosystems are dynamic systems that are constantly
changing and requiring change
 If systems are disturbed then the recovery process is
called ecological succession
Ecological Succession
 Succession is represented by gradual changes in the
species within a community over time
 Two types:
 Primary succession: the establishment of an ecosystem
where one did not exist before
 Secondary succession: the re-establishment of an
ecosystem after a disturbance where remnants of a
biological community have been left behind
Primary Succession
 Begins in a place that has no soil and no living species
 The first species that move into an area are called
pioneer species
Lichen is an example of a
pioneer species that is able to
break solid rock down into soil
through chemical weathering
processes
Primary Succession
 Lichens: a symbiotic relationship between algal or
cyanobacterial cells that are photosynthetic and a
fungus.
 The fungi provides support, water and minerals and are
able to decompose organic material.
 The algae or bacteria provide sugars through
photosynthesis.
Primary Succession
 As lichens die they break down into
organic material that enters the
newly made soil
 Once nutrient rich soil has been
created other small plant species
are able to enter the ecosystem and
find the nutrients necessary to
survive
Primary Succession
 As small plants continue to add organic matter to the
soil larger organisms are then able to be supported by
the ecosystem
Secondary Succession
 With soil and some biologic activity in the
environment secondary succession takes less time to
develop nutrients to support larger organisms
Climax community
 A climax community is the goal of succession in an
environment because it marks a period of stability after a
disturbance and is characterized by mature organisms
that are able to reach sustainability in the ecosystem
Succession patterns in NC
 The types of intermediate and
climax plants that arise during
succession depend on the
surrounding environment
 Succession in most North
Carolina environments result in
pine species during the
intermediate phases that then
give way to hardwood species
like oak and hickory trees
Succession patterns in NC
 During the intermediate stages pine tree development
occurs relatively quickly and creates a forest canopy that
blocks sunlight from reaching shrubs and underbrush
 Without sunlight, the forest floor clears and creates a
bed of leaf litter that chokes out new pine seedlings
leaving room for the hardwood saplings to take root and
thrive
 As hardwoods flourish they choke out the pine trees to
reduce competition for nutrients
Succession Patterns in NC