Bryophyte communities in Quercus garryana ecosystems on South East Vancouver Island: Preliminary mesohabitat assessment

Abstract

Quercus garryana ecosystems are threatened Mediterranean-like sites that occur in a limited range on the west coast of North America. This ecosystem has higher plant diversity and rarity than any other in British Columbia with less than 10% remaining as relicts due to habitat loss, fragmentation, and degradation. The bryophyte component remains understudied, and identification of habitat associated communities could provide a more accurate picture of ecosystem health at remaining sites. We used floristic habitat sampling and multivariate analyses to determine bryophyte diversity and community composition among three prominent mesohabitats (meadows, outcrops, Quercus garryana epiphytes) in five intact sites. We found that total species richness was highest in meadows (67), high in outcrops (63), and lowest on Quercus garryana (40) and included 11 provincially rare species. Alpha diversity and mean transformed abundance classes were significantly lower in the Quercus garryana mesohabitat versus meadows and outcrops. Multi-response permutation procedure indicated the Quercus garryana epiphytic community as statistically unique, whereas there was no significant difference between meadow and outcrop mesohabitat communities. Several species were identified as indicators for each mesohabitat type. Observations were compiled with micrographic images as a special project using the citizen science application iNaturalist. This study of Quercus garryana ecosystems from southeastern Vancouver Island, B.C., provides a preliminary mesohabitat assessment for bryophytes in this rare and threatened heterogeneous ecosystem. These baseline results can help identify priority sites for restoration based on habitats associated with bryophyte species diversity.