Nutrient availability indicators

Bridgham S. D., Updergraff K., and Pastor J. (2001) A comparison of nutrient availability indices along an ombrotrophic-minerotrophic gradient in Minnesota wetlands. Soil Sci. Soc. Am. J. 65, 259—269. 

The effects that changes in vegetation have on soil carbon pools and nutrient availability are also difficult to evaluate. However, several models have been successful in predicting vegetation-soil nutrient relationships because they assume that such changes occur as a result of different rates of decomposition and nutrient release from leaf litter of different taxa 50, 60), Such predictions could be tested and the models refined or parameterized for new taxa by measuring soil nutrient availability and respiration in stands of different species on the same soil type. For example, fifty years ago the U.S. Civilian Conservation Corps (CCC) established such stands as species trial plots measurements in some indicate large differences in soil nutrient availability (48), Further measurements in these stands would now occur at the same time-scale at which we expect the feedback between species replacement and soil processes to occur. 

The increased input of nutrients and other pollutants to rivers and estuaries may have been exacerbated by the destruction of large areas of fresh and salt water wetlands, often for agriculture (Figs 2 and 3). For example, in the United States, in 1950 there were over 100,000,000 acres (over tOx I0 > hectares) of wetlands being drained (Shaw and Fredine, 1956). The impact of wetlands on water quality is difficult to quantify (Nixon, 1980), but the few annual mass balance studies that are available indicate that these environments serve as sinks (though of widely varying strength) for nutrients (Fig. 4) and a number of... 

Tiessen, H., Stewart, J.W.B. and Oberson, A. (1994) Innovative phosphorus availability indices assessing organic phosphorus. In Havlin, J.L., Jacobsen, J., Fixen, J. and Hergert, C. (eds) Soil Testing Prospects for Improving Nutrient Recommendations, SSSA Special Publication 40. Soil Science Society of America, Madison, Wisconsin, pp. 141-1 62. 

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