Abstract Detail

Bryological and Lichenological Section/ABLS

Baldwin, Lyn, K. [1], Bradfield, Gary, B. [1].

Remnant patch size influences bryophyte richness and abundance in British Columbia temperate rainforests: implications for management.

The species richness and abundance of bryophytes within taxonomic and functional groups was examined in relation to the size of 20 old-growth forest remnant patches remaining after logging in two forest types on Vancouver Island, British Columbia. To control for the confounding effects of habitat diversity and patch area, bryophytes were sampled in sixty-three 10 cm x 30 cm microplots on three substrate-types (forest floor, downed logs and tree bases). Generalized linear models demonstrated that decreasing patch size was associated with diminished bryophyte richness and abundance. In particular, the richness and abundance of dispersal-limited groups (perennial stayers) and microclimate sensitive groups (closed canopy species and liverworts) showed significant declines in either richness or abundance as patch size decreased. In contrast, groups expected to increase as patch size decreased (colonists and open canopy species) showed little association (positive or negative) with patch size. The abundance of seven species (all species typically found under closed forest canopies) was significantly related to patch size. The use of bryophyte functional groups illustrates that although overall bryophyte richness was significantly correlated with patch size, this relationship is not true for all groups. Furthermore the influence of the three smallest patches (sized 0.6, 0.7, and 1.8 ha) in the regression model implies that variable retention practices implemented with larger patches (i.e., greater than 3.5 ha) would have a greater potential to provide reservoirs of bryological diversity in harvested landscapes.

1 - University of British Columbia, Botany Department, 3529-6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada

Keywords:
patch size
bryophyte
species richness
fragmentation
variable retention logging
old-growth
temperate rainforests
functional groups.

Presentation Type: Paper
Session: 47-6
Location: Magpie (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 10:15 AM
Abstract ID:184