ch2 Flashcards
System =
regularly interacting and interdependent components forming a unified whole
Ecosystem
= an ecological system;
= a community and its physical environment treated together as a functional system
Ecology
(from Greek: “house”, or “environment”; “study of”) is the scientific analysis and study of interactions among organisms and their environment.
It is an interdisciplinary field that includes biology, geography, and Earth science.
OR, MORE SIMPLY
an ecosystem is composed of
(size)
the organisms and physical environment of a specified area.
SIZE: micro to MACRO
THE RULES OF ECOLOGY
F. A. BAZZAZ
H. T. Odum
F. A. BAZZAZ:
- Everything is connected to everything else.
- Everything must go somewhere.
- There is no such thing as a free lunch.
H. T. Odum:
To understand any system you must understand the next larger system.
ENERGY FLOW IN ECOSYSTEMS
All organisms require energy,
for growth, maintenance, reproduction, locomotion, etc.
Hence, for all organisms there must be:
- A source of energy
- A loss of usable energy
Types of energy
heat energy
mechanical energy (+gravitational energy, etc.)
chemical energy = energy stored in molecular bonds
Transformations of energy
How is solar energy converted to chemical energy?
How does this process influence life as we see it on earth?
The transformations of energy from solar radiation to chemical energy and mechanical energy and finally back to heat are a traditional topic of Ecosystem Ecology.
An ecosystem has ………………….. and …………………… components
An ecosystem has abiotic and biotic components:
An ecosystem has abiotic and biotic components:
ABIOTIC components:
- Solar energy provides practically all the energy for ecosystems.
- Inorganic substances, e.g., sulfur, boron, tend to cycle through ecosystems.
- Organic compounds, such as proteins, carbohydrates, lipids, and other complex molecules, form a link between biotic and abiotic components of the system.
BIOTIC components:
- The biotic components of an ecosystem can be classified according to their mode of energy acquisition.
- In this type of classification, there are: Autotrophs and Heterotrophs
Autotrophs
(=self-nourishing) are called primary producers.
Photoautotrophs
fix energy from the sun and store it in complex organic compounds
(= green plants, algae, some bacteria)
Chemoautotrophs
(chemosynthesizers) are bacteria that oxidize reduced inorganic substances (typically sulfur and ammonia compounds) and produce complex organic compounds.
Other chemoautotrophs:
Nitrifying bacteria in the soil under our feet!
Heterotrophs
- Heterotrophs (=other-nourishing) cannot produce their own food directly from sunlight+ inorganic compounds.
- They require energy previously stored in complex molecules.
(this may include several steps, with several different types of organisms)
Heterotrophs can be grouped as:
- consumers
- decomposers
Consumers feed on
organisms or particulate organic matter
Decomposers utilize
complex compounds in dead protoplasm.
………………………………………… are the main groups of decomposers
Bacteria and fungi
………………………… are the main feeders on animal material.
bacteria
Bacteria are the main
feeders on animal material
…………………….. feed primarily on plants
fungi
Fungi feed primarily on plants, although bacteria also are important in
some plant decomposition processes
Bacteria and fungi are the main groups of
decomposers
Energy flow is a
one-directional process.
sun—> heat (longer wavelengths)
FIRST LAW of THERMODYNAMICS:
Energy can be converted from one form to another, but cannot be created or destroyed
SECOND LAW of THERMODYNAMICS
- Transformations of energy always result in some loss or dissipation of energy
or - In energy exchanges in a closed system, the potential energy of the final state will be less than that of the initial state
or - Entropy tends to increase (entropy = amount of unavailable energy in a system)
or - Systems will tend to go from ordered states to disordered states (to maintain order, energy must be added to the system, to compensate for the loss of energy)
SECOND LAW of THERMODYNAMICS example
Internal combustion engines in cars are 25% efficient in converting chemical energy to kinetic energy; the rest is not used or is lost as heat.
Energy flow
diagram
This pattern of energy flow among different organisms is the TROPHIC STRUCTURE of an ecosystem.
trophic
TROPHIC: Describing the relationships between the feeding habits of organisms in a food chain
It is useful to distinguish different types of
organisms within these major groups, particularly within the consumer group.
We can further separate the TROPHIC LEVELS, particularly the
consumers
We can further separate the TROPHIC LEVELS, particularly the Consumers:
Producers (Plants, algae, cyanobacteria; some chemotrophs)–capture energy, produce complex organic compounds
Primary consumers–feed on producers
Secondary consumers–feed on primary consumers
Tertiary consumers–feed on secondary consumers
Algae are
a diverse group of aquatic organisms that have the ability to conduct photosynthesis.
more trophic levels other than (producers, primary consumers, secondary, tertiary)
Detritivores–invertebrates that feed on organic wastes and dead organisms (detritus) from all trophic levels
Decomposers–bacteria and fungi that break down dead material into inorganic materials
decomposers: is a ……………………………….. while …………………………………… are one of the classifications of decomposers
“Decomposer” is a general term while detritivores are one of the classifications of decomposers.
2.Decomposers…………………………….. through …………………….. while the detritivores ………………………………………..
break down the dead organisms
decomposition
consume the decaying organisms.
Most decomposers are in the forms of ………………………… whereas the detritivores come in …………………………………………………………
bacteria or fungus
different forms, namely; worms, millipedes, dung flies, and slugs in the terrestrial aspect.
Alternate Terminology
producers
herbivores
carnivores
omnivores
Producers = plants etc. that capture energy from the sun
Herbivores = plant-eaters
Carnivores = animal-eaters
Omnivores–eat both animals and plants
- Producers = plants etc. that capture energy from the sun
- Herbivores = plant-eaters
- Carnivores = animal-eaters
- Omnivores–eat both animals and plants
Specialized herbivores:
Granivores–seed-eaters
Frugivores–fruit-eaters
Carnivores can be further divided into groups:
quaternary carnivore (top)
tertiary carnivore
secondary carnivore
primary carnivore
top carnivore
The last carnivore in a chain, which is not usually eaten by any other carnivore
Food chains
the problem with this food chain is its
- Too simplistic
- No detritivores
- Chains too long
food chains
- Too simplistic
- No detritivores
- Chains too long
More typically, there are
multiple interactions, so that we end up with a FOOD WEB.
Primary productivity
Primary productivity is the rate of energy capture by producers.
= the amount of new biomass of producers, per unit time and space
Secondary productivity is
the rate of production of new biomass by consumers, i.e., the rate at which consumers convert organic material into new biomass of consumers.
Secondary productivity is the rate of production of new biomass by consumers, i.e., the rate at which consumers convert organic material into new biomass of consumers.
Note that secondary production simply involves
the repackaging of energy previously captured by producers–no additional energy is introduced into the food chain.
Ecological pyramids
The standing crop, productivity, number of organisms, etc. of an ecosystem can be conveniently depicted using “pyramids”, where the size of each compartment represents the amount of the item in each trophic level of a food chain.
Ecological pyramids
The standing crop, productivity, number of organisms, etc. of an ecosystem can be conveniently depicted using “pyramids”, where the size of each compartment represents the amount of the item in each trophic level of a food chain.
note that
the complexities of the interactions in a food web are not shown in a pyramid; but, pyramids are often useful conceptual devices–they give one a sense of the overall form of the trophic structure of an ecosystem.
Pyramid of energy
A pyramid of energy depicts the energy flow, or productivity, of each trophic level.
Pyramid of energy
A pyramid of energy depicts the energy flow, or productivity, of each trophic level.
Due to the
Laws of Thermodynamics, each higher level must be smaller than lower levels, due to loss of some energy as heat (via respiration) within each level.
Pyramid of numbers
A pyramid of numbers indicates the number of individuals in each trophic level.
Pyramid of numbers
A pyramid of numbers indicates the number of individuals in each trophic level.
Since the size of individuals may
vary widely and may not indicate the productivity of that individual, pyramids of numbers say little or nothing about the amount of energy moving through the ecosystem.
Pyramid of standing crop
A pyramid of standing crop indicates how much biomass is present in each trophic level at any one time.
Pyramid of standing crop
A pyramid of standing crop indicates how much biomass is present in each trophic level at any one time.
As for pyramids of numbers, a pyramid of standing crop may
not well reflect the flow of energy through the system, due to different sizes and growth rates of organisms.
(at one point in time)
Inverted pyramids
A pyramid of standing crop (or of numbers) may be inverted, i.e., a higher trophic level may have a larger standing crop than a lower trophic level.
Inverted pyramids
A pyramid of standing crop (or of numbers) may be inverted, i.e., a higher trophic level may have a larger standing crop than a lower trophic level.
This can occur if
the lower trophic level has a high rate of turnover of small individuals (and high rate of productivity), such that the First and Second Laws of Thermodynamics are not violated.
(at one point in time)
Pyramid of yearly biomass production
If the biomass produced by a trophic level is summed over a year (or the appropriate complete cycle period), then the pyramid of total biomass produced must resemble the pyramid of energy flow, since biomass can be equated to energy.
Note that pyramids of energy and yearly biomass production can
never be inverted, since this would violate the laws of thermodynamics.
Note that pyramids of energy and yearly biomass production can never be inverted, since this would violate the laws of thermodynamics.
Pyramids of standing crop and numbers can
be inverted, since the amount of organisms at any one time does not indicate the amount of energy flowing through the system.
Ecosystem diversity
It is the variation in the ecosystems found in a region or the variation in ecosystems over the whole planet.
Ecological diversity includes the variation in both terrestrial and aquatic ecosystems.
Ecological diversity can also take into account the variation in the complexity of a biological community, including the number of different niches, the number of trophic levels and other ecological processes.
Ecosystem diversity example
An example of ecological diversity on a global scale would be the variation in ecosystems, such as deserts, forests, grasslands, wetlands and oceans.
Ecological diversity is the largest scale of biodiversity, and within each ecosystem, there is a great deal of both species and genetic diversity.
