Field and ground layer vegetation in a mature Norway spruce (Picea abies L.) forest of Myrtillus-type in Kuorevesi, southern Finland, was sampled on 31 plots of sizes 0.5, 1 and 2 m to find optimal balance among sampling effort, number of observed species, and accuracy of mean species-cover estimates. Rarefaction and bootstrapping were used in the data analysis. According to the results, the ad...