An Evaluation of Methods for Estimating the Net Aerial Primary Productivity of Estuarine Angiosperms

Abstract

Five harvest methods peak standing crop, and the methods of Milner and Hughes (1968), Smalley (1959), Valiela, Teal and Sass (1975), and Wiegert and Evans (1964) were used to estimate the net aerial primary production (NAPP) of angiosperm species [Borrichia frutescens, Distichlis spicata, Iva frutescens, Juncus gerardi, Phragmites communis, Spartina alterniflora, S. patens, S. cynosuroides and Sporobolus virginicus] in coastal salt marshes of eastern USA. Differences as great as 10-fold were found between the 5 methods. All methods except that of Wiegert and Evans underestimated NAPP. Wiegert and Evans'' method may have overestimated NAPP. The ranking of species by NAPP, which may be used as a measure of their importance to the estuarine system, varied between methods. The morphology of the species, the location and the general environmental conditions may affect the results of any single method. These factors must be considered before selecting a particular harvest method. Future work should assess the precision of the methodologies.