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The rate at which plants and other photosynthetic organisms produce organic compounds in an ecosystem.

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Primary Productivity

Primary productivity is a term used to describe the rate at which plants and other photosynthetic organisms produce organic compounds in an ecosystem. There are two aspects of primary productivity:

Gross productivity = the entire photosynthetic production of organic compounds in an ecosystem.

Net productivity = the organic materials that remain after photosynthetic organisms in the ecosystem have used some of these compounds for their cellular energy needs (cellular respiration).

Since oxygen is one of the most easily measured products of both photosynthesis and respiration, a good way to gauge primary productivity in an aquatic ecosystem is to measure dissolved oxygen. We cannot measure gross productivity directly because respiration, which uses up oxygen and organic compounds, is always occurring simultaneously with photosynthesis-but we can measure it indirectly. Let's see how to do this.

We can measure net productivity directly by measuring oxygen production in the light, when photosynthesis is occurring.

We can also measure respiration without photosynthesis by measuring O₂ consumption in the dark, when photosynthesis does not occur.

Since net productivity = gross productivity − respiration, we can calculate gross productivity.

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Primary productivity is a term used to describe the rate at which plants and other photosynthetic organisms produce organic compounds in an ecosystem. There are two aspects of primary productivity: Gross productivity = the entire photosynthetic production of organic compounds in an ecosystem.

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How energy moves through living organisms in an ecosystem

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How energy moves through living organisms in an ecosystem

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Energy starts with plants and trees using photosynthesis to create energy from the sun. Then the plants either get eaten or decompose which feeds about 10% of the original energy to the herbivore that eats it. The 10% of remaining energy that gets transferred into the next organism is called biomass. Then another animal, this time a carnivore eats that herbivore, getting about 1% of the original energy. Now another carnivore can eat that carnivore and get about 0.1% of the original energy. This explains why Carnivores need more food than herbivores because the carnivores aren't getting as much energy from their food.

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To many people, the most familiar forms of renewable energy are the wind and the sun. But biomass (plant material and animal waste) is the oldest source of renewable energy, used since our ancestors learned the secret of fire.

Biomass is a renewable energy source not only because the energy in it comes from the sun, but also because biomass can re-grow over a relatively short period of time compared with the hundreds of millions of years that it took for fossil fuels to form. Through the process of photosynthesis, chlorophyll in plants captures the sun's energy by converting carbon dioxide from the air and water from the ground into carbohydrates-complex compounds composed of carbon, hydrogen, and oxygen. When these carbohydrates are burned, they turn back into carbon dioxide and water and release the energy they captured from the sun.

Several recent studies show little to no economic potential to increase biopower in the U.S. over the next two decades because of its relatively high costs compared with other renewable energy and low carbon technologies ( EIA 2015, EPA 2015, NREL 2015, UCS 2014, UCS 2015). Other studies of nearly decarbonizing the power sector by mid-century show that more efficient, advanced biopower technologies using low-carbon feedstocks, such as agricultural residues and energy crops, could provide a modest contribution of up to 15 percent of U.S. electricity generation ( NREL 2012, UCS 2013).

But like all our energy sources, biopower has environmental risks that need to be mitigated. If not managed and monitored carefully, biomass for energy can be harvested at unsustainable rates, damage ecosystems, produce harmful air pollution, consume large amounts of water, and produce net global warming emissions.

Assessing the potential role of biopower as a climate solution requires a look at its lifecycle carbon emissions-which vary according to the type of feedstock, the manner in which it is developed and harvested, the scale at which it is used and the technology used to convert biomass into electricity. The lifecycle carbon emissions of biopower should also be compared to the fossil fuels it's displacing and other zero and low carbon solutions it's competing with.
NOTE: We are currently in the process of updating the content on this page to reflect the latest research and understanding of key biomass issues. Check back soon for updates.

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How biomass energy works. Renewable energy technologies tap into natural cycles and systems, turning the energy all around us into usable forms. Wind, solar, geothermal, hydroelectric, and biomass energy are all clean, natural resources that can supply our needs in a sustainable way.

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Tropical Rainforest

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Energy is flowing in a cycle

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Mr G's Environmental Systems " 1.1. 7: Flows and Storages

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Energy Flows through an ecosystems in the form of carbon-carbon bonds within organic compounds. These bonds ae broken during respiration when carbon joins with oxygen to produce carbon dioxide. Respiration releases enrgy that is either used by organisms (life processes) or is lost as heat.

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C6H12O6+6 O2+6 H2O -->12H2O+6 CO2

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Food Chain

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Food Web

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Example of Energy Through a Pyramid Model

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Example of Energy Through a Pyramid Model

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Energy/Ecological Pryamid

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Energy Efficiency Model

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Plants that use photosynthesis=Producers
Organisms that eat the plants= Comsumers

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Scientists refer to green plants as producers because they effectively produce the food for the entire food chain. Green plants use the process of photosynthesis to capture light energy, combine it with carbon dioxide and water, and then form sugars to store the energy chemically. The organisms that eat these plants are called consumers. Sometimes a distinction is drawn between primary consumers, which eat green plants, and secondary consumers, which eat other consumers.

The amount of energy present at each step in the process is much less than was in the preceding step. This means that eventually, the energy is gone, and no further energy is left. At the bottom of the food chain, organisms called scavengers feed off the last remaining bits of energy in an organism. These scavengers then release the remaining minerals and nutrients from their food into the environment where they are recycled.
Learn more about Earth Science

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How Does Energy Move Through an Ecosystem?

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Scientists refer to green plants as producers because they effectively produce the food for the entire food chain. Green plants use the process of photosynthesis to capture light energy, combine it with carbon dioxide and water, and then form sugars to store the energy chemically. The organisms that eat these plants are called consumers.