Moisture
In contrast, many bryophytes can thrive under continuously wet conditions (Proctor 2000). Thus, bryophyte biomass is generally highest in rainforests,
However, the typical abundance sequence (bryophytes—cyanolichens—chlorolichens) recurs along gradients of decreasing moisture availability at multiple spatial scales.
Relative heights of peak abundances for the different epiphyte groups vary according to the prevailing moisture regime. In rainforests, bryophytes are abundant throughout the vertical profile and lichens are only abundant in the upper canopy (Sillett and Goward 1998; Ellyson and Sillett 2003).
In moist montane forests, bryophytes dominate the lower canopy, (McCune 1993; Sillett and Rambo 2000).
In relatively dry montane forests and wet interior forests, bryophytes are restricted to the lower canopy and understory (Lesica et al. 1991; McCune et al. 1997; Clement and Shaw 1999).
In very dry interior forests, bryophytes are essentially restricted to the forest floor.