Measurement of Biodiversity (MoB): A method to separate the scale‐dependent effects of species abundance distribution, density, and aggregation on diversity change

1. Little consensus has emerged regarding how proximate and ultimate drivers such as abundance, productivity, disturbance, and temperature may affect species richness and other aspects of biodiversity. Part of the confusion is that most studies examine species richness at a single spatial scale and ignore how the underlying components of species richness can vary with spatial scale. 2. We provide an approach for the measurement of biodiversity (MoB) that decomposes scale-specific changes in richness into proximate components attributed to: 1) the species abundance distribution, 2) density of individuals, and 3) the spatial arrangement of individuals. We decompose species richness using a nested comparison of individual- and plot-based species rarefaction and accumulation curves. 3. Each curve provides some unique scale-specific information on the underlying components of species richness. We tested the validity of our method on simulated data, and we demonstrate it on empirical data on plant species richness in invaded and uninvaded woodlands. We integrated these methods into a new R package (mobr). 4. The metrics that mobr provides will allow ecologists to move beyond comparisons of species richness at a single spatial scale towards a more mechanistic understanding of the drivers of community organization that incorporates information on the scale dependence of the proximate components of species richness.