Ecosystems Overview of 8-3 Ecosystems Ecosystem Classification
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Ecosystems Overview of 8-3 Ecosystems Ecosystem Classification of Organisms in an Ecosystem Trophic levels Biomass Flow of Energy Through Ecosystems Producers, Consumers & Decomposers Ecological Pyramid Ecosystem Productivity Ecology The study of interactions among and between organisms in their abiotic environment Broadest field in biology Bioticliving environment Includes all organisms Abioticnon living or physical environment Includes living space, sunlight, soil, precipitation, etc. Ecosystem All the organisms (living things) in a given area and the abiotic (physical, non-living) environment Organisms and abiotic features interact in an ecosystem Ecosystems can vary in size Ecosystems can overlap and organisms can move between ecosystems Biotic Features All the living things in a given area, include: Species A group of similar organisms whose members freely interbreed and produce fertile offspring Population A group of organisms of the same species that occupy that live in the same area at the same time Community All the populations of different species that live and interact in the same area at the same time Abiotic Features All the non-living things in a given area, include: Weather Water Topography Nutrients Physical features Atmosphere 1 Law of Conservation of Energy Energy cannot be created or destroyed; it can change from one form to another Ex: organisms cannot create energy they need to survive- they must capture it from another source When energy is converted form one form to another, some of it is degraded to heat Law of Conservation of Matter Matter cannot be created or destroyed; it can change from one form to another Ex: plants convert carbon dioxide and water into glucose and oxygen Solar Energy About 1022 Joules of energy from the Sun reaches the Earth each day Only 1% of that energy (1020 Joules) is captured by plants (producers), the other 99% is reflected or absorbed by soil, rocks, water, and clouds Energy Reactions in an Ecosystem Photosynthesis or Chemosynthesis – transform solar energy or chemical energy from inorganic substances into chemical energy that living things can use Respiration - releases energy trapped by photosynthesis or chemosynthesis in the cells of living things to do biological work Happens in the mitochondria of cells and uses oxygen Photosynthesis Biological process by which energy from the sun (radiant energy) is transformed into chemical energy of sugar molecules Energy captured by plants via photosynthesis is transferred to the organisms that eat the plants Cellular Respiration The process where the chemical energy captured in photosynthesis is released within cells of plants and animals This energy is then used for biological work Creating new cells, reproduction, movement, etc. Trophic Levels Trophic Level- includes a group of organisms that obtain food in a similar manner Producers – convert solar or chemical energy into chemical energy that can be used by living things Herbivores – consume only producers, plants, algae, and other plant-like protists Carnivores – consume other animals Omnivores – consume both plants and animals Detritivores - consume dead organic material rather than living organisms Scavengers – feed from remains of organisms killed by omnivores or carnivores, insects, vultures, hyenas, and the like Bacteria Fungi – mold, mushrooms Energy Flow Passage of energy in a one-way direction through an ecosystem Producers ο Primary consumers ο Secondary consumers ο Decomposers Food Chains- The Path of Energy Flow Energy from food passes from one organisms to another Each “link” is called a trophic level 2 Food webs represent interlocking food chains that connect all organisms in an ecosystem Ecological Pyramids Graphically represent the relative energy value of each trophic level Important feature is that large amount of energy are lost between trophic levels to heat Three main types Pyramid of numbers Pyramid of biomass Pyramid of energy Pyramid of Numbers Illustrates the number of organisms at each trophic level Usually, organisms at the base of the pyramid are more numerous Pyramid of Biomass Illustrates the total biomass at each successive trophic level Biomass: measure of the total amt of living material (dry material) Only uses samples from populations, so difficult to measure biomass exactly. Time of year that biomass is measured affects the result. Organisms of the same size do not necessarily have the same energy content. Pyramid of Energy Illustrates how much energy is present at each trophic level and how much is transferred to the next level Most energy dissipates between trophic levels During the transfer of energy from organic food from one trophic level to the next, only about ten percent of the of energy from organic matter is stored as flesh – which is measured as biomass. The remaining is lost during transfer, broken down in respiration, used to help the organism grow and reproduce, or lost because higher trophic levels can’t digest it. General pyramid trends A healthy ecosystem will always have the most energy available in the first trophic level. The number of trophic levels are limited. At each trophic level, there is a dramatic reduction in energy. Eating at lower trophic levels means more resources available. For example: Herbivores have more resources available than 2nd level carnivores. Summary: The energy of an ecosystem is derived from the energy of the Sun. Plants use the Sun’s energy for photosynthesis to produce their own food. When herbivores eat the plants, energy from the plants is obtained by the herbivores. When carnivores eat herbivores, they obtain energy from the carnivores. When scavengers consume carnivores, they obtain the energy from the carnivores. The energy at each level of an ecosystem is contained in the biomass of organisms at that level. Therefore energy is transferred from one level to another as consumers in one level eat the biomass from the level below. In Investigation 1, students modeled the trophic layers of an ecosystem and determined the amount of energy transferred between them. The amount of energy in an ecosystem is affected by the amount of energy that plants are able to capture through photosynthesis. The amount of energy in an ecosystem is also 3 determined by the amount of biomass in the ecosystem since a greater amount of biomass in the producer level results in a greater amount of the Sun’s energy that can be captured. In Investigation 1, the relationship between the biomass of each layer and the energy of each layer was modeled. The amount of photosynthesis determines the amount of energy that is stored by the producers in their biomass and can move through the ecosystem. The amount of energy that can be captured by plants is determined by the amount of energy that reaches the earth from the Sun. The efficiency of energy transfer is affected by the use of some energy by an organism to survive. All organisms must use some energy to live, and therefore cannot store all the energy that they consume. Therefore, the transfer of energy from one level to another is not 100% efficient. This was demonstrated by the “Live Herbivore” model in Investigation 2. The “Live Herbivore” consumed oxygen, indicating that it was using energy to live and survive. The energy used by the herbivore to live was no longer available to any organism that might consume the herbivore. The “Dead Herbivore” model was not able to consume oxygen, indicating that it could not use energy. The amount of energy stored by producers determines the amount of biomass they can form. The amount of biomass and energy in the producer level determines the amount of biomass and energy that can be produced in each of the upper levels of the ecosystem. As the amount of biomass and energy increases in upper levels, the greater the number of levels an ecosystem can support. This was demonstrated in Investigation 3 when a greater number of herbivores was able to support a greater and more diverse number of carnivores. Trends – the amount of biomass decreases as they progress upward through the ecosystem. The same is true for the numbers of animals in each level of the ecosystem. Formulas to use: Total biomass in ecosystem = biomass per square meter x area of ecosystem Number of herbivores in a level = Number of carnivores A = Number of carnivores B = πππ‘ππ πππππ‘ ππππππ π πππππ‘ ππππππ π πππ π»πππππ£πππ πππ‘ππ π»πππππ£πππ ππππππ π π»πππππ£πππ ππππππ π πππ πΆπππππ£πππ π΄ πππ‘ππ πΆπππππ£πππ π΄ ππππππ π πΆπππππ£πππ π΄ ππππππ π πππ πΆπππππ£πππ π΅ Etc. 4
