Nitrogen cycle control

Model populations or communities can be established in the laboratory or in the field which they simulate, but they do not exactly reproduce the real situation. They can be used to run controlled experiments with adequate replication and can demonstrate the effects of chemicals on ecological processes such as the carbon and nitrogen cycles discussed in Chapter 7. 

In both proposed feedback mechanisms, the dominant controUing factor is the surface ocean NO3 to PO ratio (see Fig. 1.16). Both feedbacks are expected to operate in situations of excess NO3 (i.e., high NOj to PO ratio, shown at the bottom of the feedback loop in Fig. 1.16), as well as in situations ofNO deficiency (i.e., low NO to PO ratio, shown at the top of the feedback loop), if this view is correct, these two feedbacks would provide a rather tight control of the marine nitrogen cycle, creating a well balanced homeostasis. A further consequence is that... 

Figure l.l6 Schematic representation of feedbacks within the marine nitrogen cycle. The inner light grey ellipse shows the two nitrogen cycle internal feedback loops that tend to be stabilizing. These two feedback are proposed to be mainly controlled by the NO to (N P) ratio in sur-... 

Eyre, B. D., and Ferguson, A. J. P. (2005). Benthic metabolism and nitrogen cycling in a subtropical east Australian estuary (Brunswick) Temporal variability and controlling factors. Limnol. Oceangor. 50(1), 81-96. 

Pedersen, A. G. U., Bemtsen, J., and Lomstein, B. A. (1999). The effect of eelgrass decomposition on sediment carbon and nitrogen cycling A controlled laboratory experiment. Limnol. Oceanogr. 44(8), 1978-1992. 

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