Diversity and distribution of stream bryophytes: does pH matter?

Bryophytes can strongly influence biodiversity and ecosystem function in low-order streams. Mosses and liverworts have substantial biodiversity and biomass in streams, yet few investigators have examined which factors influence bryophyte species distributions, and fewer have examined assemblages across a wide pH gradient. We examined bryophyte assemblages across a pH gradient in 26 southeastern New York (USA) streams. We recorded bryophyte species richness, diversity, and abundance, in conjunction with pH, width, depth, canopy cover, substratum size, temperature, dissolved O2, turbidity, conductivity, current velocity, dissolved organic C, dissolved Ca, Mg, Fe, NH4+, NO3−, soluble reactive P (SRP), and abundance of other autotrophs. pH ranged from ∼4 to 7 and corresponded to the type of underlying bedrock. Nearly all streams had low or undetectable concentrations of SRP. Several species, e.g., Hygrohypnum eugyrium and Codriophorus aduncoides, were apparent pH generalists, whereas others were pH sp...