Estimating the abundance of subterranean propagules of submersed aquatic plants

SUMMARY 1. Data on sample means (x|) and variances (s2) of propagule abundance for five typos of aquatic plants growing in a variety of habitats were collected. The data set consisted of 379 values for x| and s2, based on 4942 individual sample units (sediment samples), drawn from the literature or from data collected as part of this study. 2. Regression analysis relating log s2 to log x| yielded an equation which was solved for the number of sample units (n) required to achieve a given degree of precision. For precise estimates [standard error (SE) = 20% of x|], values of n between twenty-seven and 234 are required when propagule density is low (