Does moisture affect the partitioning of bryophytes betweenterrestrial and epiphytic substrates within cool temperaterain forests?

摘要

Bryophyte communities are highly sensitive to moisture and/or humidity levels.Most studies on the subject focus on bryophytes on either tree or ground habitats and donot consider how bryophytes partition themselves across both ground and epiphyticsubstrates within the same forest. Sampling mesic temperate forest sites of the samephysiognomy from two Tasmanian regions with slightly different moisture levels (a wetternorthwest versus a drier northeast region), we examine various aspects of the communitystructure (overall liverwort and moss cover; species richness; and liverwort to moss ratios)of both tree and ground communities with respects to moisture availability. We then testthe hypothesis that a wetter site will exhibit a greater magnitude of bryophytes inhabitingboth tree and ground habitats. Results of the analyses show that the ground habitat in thenorthwest sites exhibited a significantly higher mean species richness, higher overall andmean liverwort to moss ratio, and a higher liverwort cover than the northeast sites. Thissuggests that the northwest had a more ameliorated ground microclimate than thenortheast. In terms of habitat partitioning, a significantly higher percentage of taxaoccupied both tree and ground habitats in the northwest, compared to the northeast,which exhibited a higher percentage of taxa restricted to trees. It is proposed that within asingle vegetation type, a higher site moisture level may create microclimates conducive tomore bryophyte species in both tree and ground habitats, especially the latter, therebyenabling taxa to colonize and coexist on both substrates more freely.