Does the similarity of the species-time and species-area relationships depend on the spatial dimension of the sample?

The species-time relationship (STR) and species-area relationship (SAR) are empirically similar; however, species tend to accumulate more rapidly in time than in space. It is likely that the differences between STRs and SARs are dependent on the nature of temporal vs. spatial sampling. The purpose of this study was to ascertain whether a SAR derived from one spatial dimension (1D; i.e. a transect) would be more similar to the STR than a SAR derived from two spatial dimensions (2D; i.e. nested square plots). We conducted our study in the grasslands of the Tallgrass Prairie Preserve in NE Oklahoma. For the 1D SARs, we recorded the presence of all vascular plant species in 1 m2 continuous quadrats along linear transects. The STRs and 2D SARs were calculated from 10 years of data collected at twenty 100 m2 quadrats at five nested spatial grains. The 1D SARs did appear more similar to the STRs than the 2D SARs. All three relationships were well characterized by power functions; however, we detected similar patterns of deviation from the fitted lines for all the relationships. Our results suggest that differences in the SAR and the STR can be explained in part by the spatial dimension of the sample.