Ecology 5


An ecosystem consists of all the organisms living in a community as well as all the abiotic factors with which they interact. Ecosystems are typically understood in terms of:

  • Energy flow through ecosystems
  • Chemical cycling within (and through)  ecosystems

Ecosystems contain essentially two kinds of commodities: matter (nutrients) and energy. The sun is the largest source of energy for the ecosystem. Light energy from the sun is converted to chemical energy by autotrophic organisms, passed to heterotrophs in the organic compounds of food, and dissipated in the form of heat. Energy flows through ecosystems mostly as bonds between carbon atoms and bonds between carbon and hydrogen atoms. Energy does not cycle through ecosystems, but instead enters ecosystems and is used up within ecosystems. Energy and matter dispense through ecosystems when organisms metabolize other organisms. Energy flow is the amount of energy that moves through a food chain (trophic levels/ Energy levels). The movements of energy and matter through ecosystems are related because both occur by the transfer of substances through feeding relationships. Unlike energy, matter is recycled. Therefore, energy flow through the ecosystem and matter flow within.

Biogeochemical Cycles

The biogeochemical cycles are pathways by which matter travel through both biotic and abiotic aspect of the earth. There are three major biogeochemical cycle: Carbon, Water and Nitrogen.

Carbon Cycle

It’s important to note that all living things are made up of carbon compound; thus making it a fundamental building block of life. It’s also a vital part of many chemical reactions. Carbon exist in the atmosphere primarily as CO2. The amount of CO2 in the atmosphere is influence mainly by the burning of fossil and also making changes to land. It is important to point out that CO2 is one of the major substance driving Global Warming, because it traps long wave radiation within our planet atmosphere. Planet Earth atmosphere constantly exchanges CO2 with the ocean. This help to regulate the amount of atmospheric CO2 level.

Video of Carbon Cycle

Water Cycle

The water cycle show how water is recycle on our planet. During cycle, water changes from liquid to solid to gas and vice versa. The water cycle is power by heat. Remember heat determine the state of matter. All living thing needs water.

Video of Water Cycle

Nitrogen Cycle

The nitrogen cycle highlights how nitrogen is converted between it’s different chemical forms. The changes involving, nitrogen can occur by both chemical and physical means. The nitrogen cycle is composed of fixation, ammonification, nitrification, and de-nitrification. Atmospheric nitrogen is not accessible to most organisms. The earth atmosphere is 78% nitrogen, making it the most abundant gas in the atmosphere. Nitrogen is a fundamental requirement for life on earth. It is needed by all living thing. Nitrogen is a key component in amino acids (protein) and nucleic acid (RNA and DNA). It’s also important for photosynthesis (chlorophyll molecules). Gaseous nitrogen is unusable to plant and therefore required conversion through fixation. Nitrogen fixation is done by bacteria (rhizobium bacteria) that converts gaseous nitrogen into compound such as nitrate and ammonia. Those compound are usable by plants.

Video of Nitrogen Cycle


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