Explaining species diversity in a fractal world

We investigated emergent rock (ER) distributions from two sets of streams in SE Scotland and SE Australia. ER were counted and channel morphology noted in contiguous 5-m segments along the study lengths (685 - 1000 m of each stream). ER of the Scottish streams were originally surveyed by Lancaster et al. [2010] and the Australian streams were surveyed during the Austral summer (December - February) of 2016/17. ER were defined as any rock protruding above the water surface, with a maximum b-dimension (width, perpendicular to longest axis) of at least 5 cm and in at least 5 cm of water. These surveys were carried out at or near summer base flow.Lancaster, J., B. J. Downes, and A. Arnold (2010), Environmental constraints on oviposition limit egg supply of a stream insect at multiple scales, Oecologia, 163(2), 373-384.