UNDERSTANDING
- Most species occupy different trophic levels in multiple food chains
- A food web shows all the possible food chains in a community
- The percentage of ingested energy converted to biomass is dependent on the respiration rate
- The type of stable ecosystem that will emerge in an area is predictable based on climate
- In closed ecosystems energy but not matter is exchanged with the surroundings
- Disturbance influences the structure and rate of change within ecosystems
APPLICATIONS
- Conversion ration in sustainable food production practices
- Consideration of one example of how humans interfere with nutrient cycling
SKILLS
- Comparison of pyramids of energy from different ecosystems
- Analysis of a climograph showing the relationship between temperature, rainfall and ecosystem type
- Construction of Gersmehl diagrams to show the inter-relationships between nutrient stores and flows between taiga, desert and tropical rainforest
- Analysis of data showing primary succession
- Investigation into the effect of an environmental disturbance on an ecosystem
NATURE OF SCIENCE
- Models are representations of the real world: pyramids of energy model the energy flow through ecosystems
TROPHIC LEVELS
Most species occupy different trophic levels is its feeding position in a food chain. Because feeding relationships within an ecosystem are often web-like, an organism can occupy more than one trophic level. For example, the diet of an owl involves animals which occupy different trophic levels
An owl pellet is a mass of undigested parts of the owl's set which it regurgitates. The contents of the pellet can be used to gather information about the owl and its community without disturbing the bird. The contents might include such things as exoskeletons of insects, bones, fur and claws
If the species found within the pellet can be identified, their trophic level can be found. Alternatively, it may be possible to deduce the trophic elves from the adaptations. The contents of a pellet often show that an owl has been feeding at more than one trophic level
- Most species occupy different trophic levels in multiple food chains
- A food web shows all the possible food chains in a community
- The percentage of ingested energy converted to biomass is dependent on the respiration rate
- The type of stable ecosystem that will emerge in an area is predictable based on climate
- In closed ecosystems energy but not matter is exchanged with the surroundings
- Disturbance influences the structure and rate of change within ecosystems
APPLICATIONS
- Conversion ration in sustainable food production practices
- Consideration of one example of how humans interfere with nutrient cycling
SKILLS
- Comparison of pyramids of energy from different ecosystems
- Analysis of a climograph showing the relationship between temperature, rainfall and ecosystem type
- Construction of Gersmehl diagrams to show the inter-relationships between nutrient stores and flows between taiga, desert and tropical rainforest
- Analysis of data showing primary succession
- Investigation into the effect of an environmental disturbance on an ecosystem
NATURE OF SCIENCE
- Models are representations of the real world: pyramids of energy model the energy flow through ecosystems
TROPHIC LEVELS
Most species occupy different trophic levels is its feeding position in a food chain. Because feeding relationships within an ecosystem are often web-like, an organism can occupy more than one trophic level. For example, the diet of an owl involves animals which occupy different trophic levels
An owl pellet is a mass of undigested parts of the owl's set which it regurgitates. The contents of the pellet can be used to gather information about the owl and its community without disturbing the bird. The contents might include such things as exoskeletons of insects, bones, fur and claws
If the species found within the pellet can be identified, their trophic level can be found. Alternatively, it may be possible to deduce the trophic elves from the adaptations. The contents of a pellet often show that an owl has been feeding at more than one trophic level
FOOD WEBS
A food web shows all the possible food chains in a community
Trophic relationships within ecological communities tend to be complex and web-like. This is because many consumers feed on more than one species and are fed upon by more than one species. A food web is a model that summarizes all of the possible food chains in a community.
When a food web is constructed, organisms at the same trophic level often shown at the same level in the web. This isn't always possible, as some organisms feed at more than one trophic level.
A food web shows all the possible food chains in a community
Trophic relationships within ecological communities tend to be complex and web-like. This is because many consumers feed on more than one species and are fed upon by more than one species. A food web is a model that summarizes all of the possible food chains in a community.
When a food web is constructed, organisms at the same trophic level often shown at the same level in the web. This isn't always possible, as some organisms feed at more than one trophic level.
THE IMPACT OF CLIMATE ON ECOSYSTEM TYPE
The type of stable ecosystem that will emerge in an area is predictable based on climate.
Climate is a property that emerges from the interaction of a number of variables including temperature and precipitation.
Temperature influences the distribution of organism. Temperature influences rates of cell respiration, photosynthesis, decomposition and transpiration and ultimately has an impact on productivity
Precipitation also impacts productivity by influencing rates of photosynthesis and rates of decomposition. Information about the relative combinations of these two factors in an area can allow for predictions about what kind of stable ecosystem will exist in that area.
RESPIRATION RATES AND BIOMASS ACCUMULATION
The percentage of ingested energy converted to biomass is dependent on the respiration rate
Production in plants happens when organic matter is synthesized by photosynthesis. In animals it occurs when food is absorbed after digestion. Energy units are usually used for measuring production e.g. kilojoules. The amounts of energy are given per unit area, usually per m2 and per year. Gross and net production value can be calculated using this equation:
net production = gross production - respiration
Gross production is the total amount of organic matter produced per unit area per unit time by a trophic level in an ecosystem
Net production is the amount of gross production remaining after subtraction of the amount used for respiration by the trophic level
In the early stages of primary production, the high availability of sunlight means that gross production is high and there is little total biomass in the community. As a result, the total amount of respiration to support the small biomass is low. As succession proceeds, the standing biomass increases and the total amount of respiration increases. Further, the amount of gross production begins to decline once all available spaces for stems become filler. An equilibrium is reached where the total community production total community respirations ration equals 1. When this occurs, the ecosystem has reached a relatively stable stage.
SECONDARY SUCCESSION
Disturbance influences the strict and rate of change within ecosystems.
Secondary succession takes place in areas where there is already, or recently has been, an ecosystem. The succession is initiated by a change in conditions. Construction sites or roads might become disused and eventually plants grow up in the remains.
The type of stable ecosystem that will emerge in an area is predictable based on climate.
Climate is a property that emerges from the interaction of a number of variables including temperature and precipitation.
Temperature influences the distribution of organism. Temperature influences rates of cell respiration, photosynthesis, decomposition and transpiration and ultimately has an impact on productivity
Precipitation also impacts productivity by influencing rates of photosynthesis and rates of decomposition. Information about the relative combinations of these two factors in an area can allow for predictions about what kind of stable ecosystem will exist in that area.
RESPIRATION RATES AND BIOMASS ACCUMULATION
The percentage of ingested energy converted to biomass is dependent on the respiration rate
Production in plants happens when organic matter is synthesized by photosynthesis. In animals it occurs when food is absorbed after digestion. Energy units are usually used for measuring production e.g. kilojoules. The amounts of energy are given per unit area, usually per m2 and per year. Gross and net production value can be calculated using this equation:
net production = gross production - respiration
Gross production is the total amount of organic matter produced per unit area per unit time by a trophic level in an ecosystem
Net production is the amount of gross production remaining after subtraction of the amount used for respiration by the trophic level
In the early stages of primary production, the high availability of sunlight means that gross production is high and there is little total biomass in the community. As a result, the total amount of respiration to support the small biomass is low. As succession proceeds, the standing biomass increases and the total amount of respiration increases. Further, the amount of gross production begins to decline once all available spaces for stems become filler. An equilibrium is reached where the total community production total community respirations ration equals 1. When this occurs, the ecosystem has reached a relatively stable stage.
SECONDARY SUCCESSION
Disturbance influences the strict and rate of change within ecosystems.
Secondary succession takes place in areas where there is already, or recently has been, an ecosystem. The succession is initiated by a change in conditions. Construction sites or roads might become disused and eventually plants grow up in the remains.
CLOSED ECOSYSTEMS
In closed ecosystems energy but not matter is exchanged with the surroundings
There are three categories of systems that can be modeled. Open systems exchange matter and energy with their surroundings. Closed systems exchange energy but not matter with the surroundings. Isolated systems, which are largely theoretical, exchange neither matter nor energy with their surroundings. Ecological systems exist along the continuum. Natural systems exchange both matter and energy with their surroundings and so are categorized as open systems. In undisturbed systems, the rate of exchange of matter with the surroundings occurs most notable due to theater cycle and nutrient cycles that have a gaseous phase. Human interference increases the exchange of matter either through harvesting of crops or addition or depletion of nutrients.
In closed ecosystems energy but not matter is exchanged with the surroundings
There are three categories of systems that can be modeled. Open systems exchange matter and energy with their surroundings. Closed systems exchange energy but not matter with the surroundings. Isolated systems, which are largely theoretical, exchange neither matter nor energy with their surroundings. Ecological systems exist along the continuum. Natural systems exchange both matter and energy with their surroundings and so are categorized as open systems. In undisturbed systems, the rate of exchange of matter with the surroundings occurs most notable due to theater cycle and nutrient cycles that have a gaseous phase. Human interference increases the exchange of matter either through harvesting of crops or addition or depletion of nutrients.
Theory of Knowledge
Do the entities in scientist's models, for example trophic levels or Gersmehl diagrams, actually exist, or are they primarily useful inventions for predicting and explaining the natural world?
I believe it is of human nature to always want to search and actually find an explanation to every question that can be asked regarding the reason our world functions in a certain way. It is the task of scientist to find an answer to these type of questions (e.g. why is most of the population born with two arms and two legs while there is a great chance of error in reproduction?) and the purpose of these models is to explain why the natural world works in a way the seems to be the most rational. Thus, I disagree with anyone who says these models actually exist; these models are created with a lot of thinking so that they can be a close and logical representation of what we think reality is like, but in actual reality, the world is too big and there can be many different possibilities as to how nature works. One person is way less than just 1% of the earth as whole, not even a 100 scientists working together would get close to being that 1%; claiming that a model is the exact representation of how nature works would be nothing but a false statement.
Do the entities in scientist's models, for example trophic levels or Gersmehl diagrams, actually exist, or are they primarily useful inventions for predicting and explaining the natural world?
I believe it is of human nature to always want to search and actually find an explanation to every question that can be asked regarding the reason our world functions in a certain way. It is the task of scientist to find an answer to these type of questions (e.g. why is most of the population born with two arms and two legs while there is a great chance of error in reproduction?) and the purpose of these models is to explain why the natural world works in a way the seems to be the most rational. Thus, I disagree with anyone who says these models actually exist; these models are created with a lot of thinking so that they can be a close and logical representation of what we think reality is like, but in actual reality, the world is too big and there can be many different possibilities as to how nature works. One person is way less than just 1% of the earth as whole, not even a 100 scientists working together would get close to being that 1%; claiming that a model is the exact representation of how nature works would be nothing but a false statement.