Extending species-area relationships into the realm of ecoacoustics: The soundscape-area relationship

The rise in species richness with area is one of the best-studied patterns in ecology. Yet, little is known about the spatial scaling of alternate dimensions of diversity. Here, we provide empirical evidence for a relationship between the richness of acoustic traits emanating from the landscape, or soundscape richness, and the island area, which we term the Soundscape Area Relationship (SSAR). We show a positive relationship between the gamma soundscape richness and island area, with slope and R2-values of comparable magnitude to those reported in the literature. This relationship breaks down at the smallest spatial scales, indicating a small-island effect. Moreover, we demonstrate a positive spatial scaling of the plot-scale alpha soundscape richness, but not the beta soundscape turnover, suggesting disproportionate effects are an important underlying mechanism. We conclude that the scaling of biodiversity can be extended to the realm of ecoacoustics, implying soundscape metrics are sensitive to fundamental ecological patterns and useful to disentangle the complex mechanisms that drive them.