Cryptic diversity in bryophyte soil-banks along a desert elevational gradient
Robert J. SmithRobert J. Smith (email@example.com), School of Life Sciences, Univ. of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154-4004, USA.
Propagule soil-banks are important for colonization and for the maintenance of regional diversity among bryophytes of temperate regions, yet they have not previously been reported from hot desert ecosystems, and little is known about the relationship between soil-bank diversity and elevation. I used emergence germination methods to explore patterns of species composition and richness in bryophyte soil-banks along a 1400 m elevational gradient spanning three major vegetation zones in the Mojave Desert (southwestern USA). A total of 17 bryophyte taxa were present in soils collected at twelve sites. Community compositions shifted with increasing elevation, suggesting that soil-banks along the gradient are an important ‘cryptic’ component of the regional species pool. Bayesian linear regressions revealed that three measures of community diversity were positively associated with elevation: species richness (SR), Shannon entropy (H’), and phylogenetically-controlled species richness (PSR). Positive diversity–elevation trends in soil-banks of the Mojave Desert are the likely product of increasing moisture availability and frequent propagule production at higher elevations in dry mountain ranges.