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

The rise in species richness with area is one of the few ironclad
ecological relationships. Yet, little is known about the spatial scaling
of alternative dimensions of diversity. Here, we provide empirical
evidence for a relationship between the richness of acoustic traits
emanating from a landscape, or soundscape richness, and island area, which
we term the SoundScape-Area Relationship (SSAR). We show a positive
relationship between the gamma soundscape richness and island area. 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 combined with acoustic niche
partitioning as an underlying mechanism. We conclude that the general
scaling of biodiversity can be extended into the realm of ecoacoustics,
implying soundscape metrics are sensitive to fundamental ecological
patterns and useful in disentangling their complex mechanistic drivers.