III.10
Nutrient Cycling and Biogeochemistry
Peter M. Vitousek and Pamela A. MatsonNutrient Cycling and Biogeochemistry
OUTLINE
| 1. | Element cycles in terrestrial ecosystems |
| 2. | Global element cycles |
| 3. | Illustration: Nutrient cycling in practice |
GLOSSARY
biological nitrogen fixation. The enzyme-mediated reduction of atmospheric dinitrogen (N2) to chemical
forms that can be used by most organisms.eutrophication. Overenrichment of ecosystems resulting from excessive additions of nutrients; eutrophication may create anaerobic conditions (“dead
zones”) in aquatic ecosystems.mineralization. With reference to phosphorus and
nitrogen, mineralization is the microbially mediated conversion of organically bound nutrients to
soluble, biologically available inorganic forms.mycorrhizae. Mycorrhizae are a symbiosis between the
roots of most higher plants and several groups of
fungi, in which the fungal partner typically derives
energy from the plant and the plant receives nutrients from the fungus.nitrification. The biologically mediated oxidation of
ammonium (NH4) to nitrate (NO3); specialized
microorganisms derive their energy from this transformation.nutrient limitation. Nutrient limitation occurs where
the rate of a biological process like productivity or
decomposition is constrained by a low supply of one
or more biologically essential elements.weathering. The breakdown of rocks and minerals, at
least partly into soluble and biologically available
components.within-system cycle. Transfers of nutrients among
plants, animals, microorganisms, and soil and/or
solution, within the boundaries of an ecosystem.We define a “nutrient” as an element that is required
for the growth of some or all organisms—and one that
plants typically acquire from soil or solution (as opposed to the uptake of carbon from gaseous forms).
The cycles of nutrients are interesting to ecologists for
many reasons, including the following:| • | A low supply of a nutrient can constrain the growth and populations of organisms and the productivity, biomass, diversity, and dynamics of entire ecosystems. |
| • | Losses of nutrients from terrestrial ecosystems represent inputs to aquatic systems and to the atmosphere. In the atmosphere, reactive nitrogen gases influence atmospheric chemistry and climate; in freshwater and marine systems, inputs of N and P can drive eutrophication (overenrichment). Element losses thus represent a useful currency for evaluating land–water and landatmosphere interactions. |
| • | The cycles of multiple elements are altered on regional and global scales by human activity. Much research in this area has focused on the global cycle of carbon, in part because of the importance of CO2 in the climate system, but |
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Questia, a part of Gale, Cengage Learning. www.questia.com
Publication information:
Book title: The Princeton Guide to Ecology.
Contributors: Simon A. Levin - Editor.
Publisher: Princeton University Press.
Place of publication: Princeton, NJ.
Publication year: 2012.
Page number: 330.
This material is protected by copyright and, with the exception of fair use, may not be further copied, distributed or transmitted in any form or by any means.
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