Trophic Levels
-Most species occupy different trophic levels in multiple food chains -This is because organisms don't eat only one specific organism, they eat a variety of organisms (just like we don't just eat one specific food) -These variety of organisms can also come from a variety of trophic levels, making the organism feeding on them belong to different trophic levels in different food chains In the picture: The tuna belongs to both the secondary and the tertiary trophic levels because it eats both small fish (which belong to the primary tl) and mackerel (which belongs to the secondary tl) |
Food Webs
-A food web shows all the possible food chains in a community
-This is used to simplify all the possible predator relations, since an organism can consume a variety of organisms and be consumed by a variety of organisms
-A food web shows all the possible food chains in a community
-This is used to simplify all the possible predator relations, since an organism can consume a variety of organisms and be consumed by a variety of organisms
Respiration Rates and Biomass Accumulation
-The percentage of ingested energy converted to biomass on the respiration rate -Gross production is the total amount of organic matter (originating with carbon compounds) produced by the intake of energy -The net production is calculated by subtracting the organic matter released through respiration from the gross production -To reach a stable community, there has to be an equilibrium between the community production and the community respiration (meaning that the consumers from the higher trophic levels will start decreasing in number because the energy passed on to them is very limited, and not all organisms from these trophic levels would obtain energy or organic matter) |
The Impact of Climate on Ecosystem Life
-The type of stable ecosystem that will emerge in an area is predictable based on climate -Climate is mostly composed of two variables: temperature and precipitation -Temperature has an impact on cell respiration, photosynthesis, decomposition, and productivity -Precipitation affects photosynthesis and decomposition. high rainfall leads to forests and low rainfall leads to deserts In the picture: flows and storage of nutrients in biomass, litter, and soil in different biomes (Gersmehl diagram) |
Secondary Succession
-Disturbance influences the structure and rate of change within ecosystems
-Secondary succession happens in areas where there is already an ecosystem living and there is a change in conditions
(abandoned meadows or construction sites)
-The slow change in the ecosystem makes the respiration and productivity increase. In result, the biomass accumulates
-The change reaches a "climax" in which the changes slow down, the community is sustainable and resistant to change
Human Impact
-Humans disturb the nutrient cycles happening in an ecosystem because of their use of nature in their industries
-Agriculture, for example, makes an ecosystem lose biomass when the crops are harvested and shipped to be commerced. This loss of biomass leads to a loss of nutrients to the cycle since these crops can't decompose and pass on the nutrients, which is why we have to constantly add fertilizers to the soil
-Disturbance influences the structure and rate of change within ecosystems
-Secondary succession happens in areas where there is already an ecosystem living and there is a change in conditions
(abandoned meadows or construction sites)
-The slow change in the ecosystem makes the respiration and productivity increase. In result, the biomass accumulates
-The change reaches a "climax" in which the changes slow down, the community is sustainable and resistant to change
Human Impact
-Humans disturb the nutrient cycles happening in an ecosystem because of their use of nature in their industries
-Agriculture, for example, makes an ecosystem lose biomass when the crops are harvested and shipped to be commerced. This loss of biomass leads to a loss of nutrients to the cycle since these crops can't decompose and pass on the nutrients, which is why we have to constantly add fertilizers to the soil
Closed Ecosystems
-In closed ecosystems energy but not matter is exchanged with the surroundings
-Open systems exchange matter and energy with it's surroundings, closed materials exchange energy but not matter, and isolated systems do not interact with it's surroundings
-Natural Sciences fall under open ecosystems and interacts with it's surroundings (most notably on the water cycle)
-In closed ecosystems energy but not matter is exchanged with the surroundings
-Open systems exchange matter and energy with it's surroundings, closed materials exchange energy but not matter, and isolated systems do not interact with it's surroundings
-Natural Sciences fall under open ecosystems and interacts with it's surroundings (most notably on the water cycle)
TOK: Although the models and systems used to organize and categorize ecosystems and their communities are a useful tool to understand the basic content of what we have learned and discovered about the world it is very possible that there are unknown ecosystems that do not correlate with these models. Yes, it has been found that be true with most of the cases, but we cannot assume that these systems will match with all organisms in the planet. For example, maybe there is an unknown and undiscovered ecosystem in which there are producers in small numbers and higher trophic levels in abundance because they're flow of energy travels in a different mechanism.