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Holly's
Shallow Dig on Decomposers: The Nutrient Cycle with a focus on the role of decomposer species: The cycling of materials such as carbon, water, and other nutrients is mainly dependent upon soil-dwelling decomposer organisms such as bacteria, fungi, earthworms, and insects. Bacteria and fungi are the most abundant of the microbial decomposers, numbering in the billions in only one handful of soil! As essential components of the environment, fungal and bacterial microbes break down dead and discarded organic materials, supplying a continuous source of nutrients for the plants in surrounding soil. In general, decomposers break down the proteins, starches, and other complex organic molecules that were all once the components of living organisms, and “as products of their own metabolism, [they] convert elements such as nitrogen, phosphorous, calcium, and sulfur into forms that can be utilized by plants” (Dirty, 2). According to several researchers at the University of Jyväskylä, "Reduction in the species diversity of the lowest levels (decomposer fungi) of the food web [become] particularly well manifested as reduced decomposition rate and stagnated nutrient dynamics." They also emphasized that certain variations of microorganisms can play a critical role in controlling nitrogen cycles and plant growth in general. In addition, it is true that decomposer species tend to be rather resistent to changes in the availablitiy of organic material or changes to the environment in general, but they are still affected by several key factors. For instance, increases in temperature will cause more rapid decomposition reactions--just as would occur for most chemical reactions. However, too high of an increase in temperature affects the microbes adversely. Moisture is also usually favorable unless there is so much moisture that the living environment is waterlogged. When waterlogging occurs, some microbes will die while others thrive on the excess moisture. On the other hand, light tends to be bad for most decomposer microbes. Concerning the issue of oil drilling on the North Slope of ANWR, one would expect an increase in the amount of organic as well as inorganic waste material in the local environment. This is important, because although fungi and microorganisms thrive off of organic materials such as animal flesh, fecies, dead plant matter, nut shells, etc., it is much harder and time consuming for them to decompose human-made materials that are either high in cellulose--i.e. cotton and paper-cardboard--or metallic or plastic. In fact, metals and plastics are almost impossible to decompose by the microorganisms and fungi--they break down primarily, and over a long period of time, due to weathering processes. Currently advances are being made in the development of biodegradable plastics, but there remains the majority of non-biodegradable plastics. Furthermore, if the diversity of decomposer species decreases in ANWR due to changes in their environment--whether the changes are related to climate, the introduction of oil drilling, or increases/decreases in populations of consumers--it can be assumed that all species that depend upon the decomposers are either directly or indirectly affected by such a flux. For a more detailed evaluation of soil dynamics and the nutrient cycle, please vi sit the web page by Team 5 (the "Characterization of the ANWR Ecosystem" team), at http://web.mit.edu/12.000/www/m2007/teams/5/research.html. For general information about decomposer species outlined in the following order, please click here.Likely Effect of Oil-Drilling on Decomposer Species: please click here. For more detailed
information concerning the facts about decomposer species existing in ANWR
and their relative importance in the decision to drill or not, please visit
my web site at:
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| Last updated: November 26, 2003 (6:08 am) | Webmistresses: Holly and Lia Team 7 - m2007-7@mit.edu |