An evaluation of methods for estimating the net aerial primary productivity of estuarine angiosperms.
Harvest methods (peak standing crop, and the methods of Milner and Hughes, Smalley, Valiela, Teal & Sass, and Wiegert & Evans) were used to estimate the net aerial primary production (NAPP) of angiosperm spp. including Spartina alterniflora, S. patens, S. cynosuroides, Sporobolus virginicus, Phragmites communis [P. australis] and Distichlis spicata in coastal salt marshes in Maine, Delaware and Georgia, USA. Differences as great as 10-fold were found between the 5 methods. All methods except that of Wiegert & Evans underestimated NAPP. Wiegert & Evans method may have overestimated NAPP. The ranking of spp. by NAPP, which may be used as a measure of their importance to the estuarine system, varied between methods. It was concluded that the morphology of the sp., the location, and the general environmental conditions affect the results of any single method and that these factors must be considered before selecting a particular harvest method. In addition, future work should assess the precision of the methodologies.