Rapid assessments of biodiversity are needed for swift management and conservation policies. In  a preliminary study, the efficiency of two area-based rapid assessment protocols (strip and variable transect methods) were compared and tested with actual census data in a 16-ha plot. The protocols greatly underestimated the plot’s diversity even with the use of species richness estimators. As this may be attributed to sampling insufficiency, the area needed for sound estimation of the plot’s species richness and diversity was approximated in this study using cumulative 1-ha quadrats. The minimum area needed to accurately measure the plot’s diversity was 3 ha to estimate Fisher’s α, and 4 ha to estimate species richness by jackknifing. Other measures needed areas ranging from 4 ha to the entire 16 ha of the plot. The strip transect method covered 0.1 ha per replicate, while the variable transect method covered 3.1 ha. The variable transect method is thus able to better represent the 16-ha plot in terms of species diversity, and should be considered in rapid assessments of sites.