Abstract Detail

Ecological Section

Haughian, Sean Ryan [1], Frego, Katherine A. [2].

Epixylic bryophyte growth response to substrate moisture capacity on synthetic and natural logs under thinned and intact forest canopies.

Coarse woody debris (CWD) is an important substrate in forest ecosystems, serving as habitat for many unique and rare taxa, especially bryophytes. Many have suggested that CWD is important because it serves as a moisture-reservoir, thereby ensuring a humid microclimate and facilitating greater bryophyte growth, however none have tested this connection experimentally. We hypothesized that, if microclimatic regulation was the primary mechanism contributing to high bryophyte abundance and diversity on CWD, then epixylic bryophytes growth would increase with the size of the moisture reservoir. Twelve replicates of four different substrates (three synthetic and one natural rotting log) were equally distributed between the recently thinned (40% basal area from below) and intact canopies of 27-year-old white spruce plantations and inoculated with two replicate mesh bags of Dicranum flagellare. The three synthetic substrates were identical in size and shape, but had modified cores to provide a gradient of moisture reservoir size, while the natural substrates were well-decayed birch and cedar logs. After almost two years of growth, surprising patterns emerged: (1) under a closed forest canopy, the type of log is not a significant determinant of bryophyte growth; (2) under an open forest canopy, bryophyte growth is significantly faster on natural substrates than synthetic ones; (3) under an open forest canopy, bryophyte growth is negatively correlated with the size of the moisture reservoir in synthetic substrates. These results suggest: (1) the provision of a humid microclimate, as mediated through substrate moisture capacity, is apparently less important as previously thought for promoting bryophyte growth, (2) light availability and/or precipitation interception may be limiting the growth of epixylic bryophytes in closed-canopy forests, and (3) improving conservation of bryophytes in managed forests requires consideration of both substrate and canopy characteristics.

Related Links:
Research Gate Profile for Sean Haughian

1 - University of New Brunswick, Biology, PO Box 5050, 100 Tucker Park Rd, Saint John, NB, E2L4L5, Canada
2 - University of New Brunswick, Biology, 100 Tucker Park Circle, Saint John, NB, E2L4L5, Canada

Keywords:
moisture
Bryophyte
synthetic log
canopy
epixylic
forests
thinning.

Presentation Type: Oral Paper:Papers for Sections
Session: 21
Location: Salon 17/18/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 2:30 PM
Number: 21005
Abstract ID:498
Candidate for Awards:Cinq Mars Award