TEMPE, Ariz. -- Anyone who has thrown a backyard barbecue knows that hot dogs are inexplicably packaged in different numbers than buns eight hot dogs per pack versus 10 hot dog buns. Put in ecological terms, this means that weenie roasts are hot-dog limited the extra buns are worthless without hot dogs to fill them.
Such limiting factors are a cornerstone of natural ecology, where phosphorus or nitrogen limits plant production in most ecosystems. According to the customary model, the relative importance of these two key nutrients varies by ecosystem; but a group of researchers led by Arizona State University professor James Elser has found that this view might need to be updated.
Their paper, Global analysis of nitrogen and phosphorus limitation of primary producers in freshwater, marine and terrestrial ecosystems, is highlighted in the News and Views section of the October 25 edition of Nature. The most comprehensive study of its kind, this meta-analysis of more than 300 publications in the field of nutrient limitation in ecosystems was recently published online in the journal Ecology Letters.
Like all living things, plants require a number of chemical elements in order to flourish, including carbon, hydrogen and oxygen. They also need nitrogen, a building block of proteins; and phosphorus, used to make the nucleotides that compose DNA and RNA. The interplay of these elements affects the growth of the food webs foundational plants, and so understanding their interplay is of vital environmental and commercial concern.
Nitrogen and phosphorus, both widely used in fertilizers, must be in proper balance to be effective. Adding nitrogen alone to an ecosystem is helpful only up to a point, after which plants stop benefiting unless phosphorus also is added. If such a system responds positively to the initial nitrogen addition, it is said to be nitrogen-limited, because the availability of nitrogen instantaneously constrains
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Arizona State University