Abstract Detail

Ecological impacts and restoration of industrial sites: roles of bryophytes and graminoid vascular plants 

Caners, Richard [1], Lieffers, Victor [2].

Bryophyte decomposition in wooded moderate-rich fens following in situ oil sands exploration.

Northern peatlands are a major sink for atmospheric carbon, storing about one third of global soil carbon as peat. In Alberta, Canada, peatlands occupy approximately 18% of the land base with the majority of these being rich fens. Peatlands accumulate carbon because of cold and waterlogged soils with poor aeration that result in the slow decomposition of organic matter. Currently, in situ oil sands exploration (OSE) in the province is widespread in regions containing peatlands. These operations remove surface vegetation, expose lower layers of non-decomposed peat, and reduce variation in surface microtopography. The consequences of OSE on the peatland environment and subsequently organic matter decomposition are unknown but have major implications for carbon sequestration. We examined the decomposition of mosses (Sphagnum fuscum, Sphagnum angustifolium, Tomentypnum nitens, Polytrichum strictum) in 10 abandoned OSE drilling pads on wooded moderate-rich fens. Pads were constructed in winter, 10 years before study onset. Five of these pads had succeeded to sedge fens with a high water table, limited elevated microsites, and poor bryophyte development (“bryophyte-poor” habitat); the other five pads developed the bryophytes and vascular plants expected of intact wooded fens (“bryophyte-dominated” habitat). On each drilling pad and in adjacent undisturbed reference habitat, moss species and temperature sensors were buried for 360 days in highest and lowest microtopographic elevations. We hypothesized that decomposition would vary by local abiotic and biotic habitat conditions generated by OSE. Moss decomposition was closely associated with the successional pathway (bryophyte-poor or bryophyte-dominated) that characterized a site after drilling. The best environmental predictors of decomposition were microtopograhpic elevation and soil temperature. Decomposition also varied by taxon, with Sphagnum fuscum biomass being most resistant to decomposition. Bryophyte-poor OSE habitat had high soil temperatures, but as these pads had waterlogged soils and few microhabitats above the usual water table, samples had lowest mass loss (mean = 13.7 ± 1.1%) across all measured species. Bryophyte-dominated OSE habitat had higher mass loss (mean = 22.7 ± 0.9%), resulting mostly from high soil temperatures and higher microsite elevations above the water table, and was similar to adjacent reference habitat. Overall, despite the major alteration of peatland habitat following OSE, carbon loss through organic matter decomposition did not exceed that of reference habitat for the two observed successional pathways. However, OSE disturbance may have long-term implications for carbon sequestration through modification of successional development and organic matter accumulation.

1 - Royal Alberta Museum, Alberta Biodiversity Monitoring Institute, 12845 - 102 Ave., Edmonton, AB, T5N 0M6, Canada
2 - University of Alberta, Department of Renewable Resources, 751 General Services, Edmonton, AB, T6G 2H1, Canada

Keywords:
bryophytes
peatlands
decomposition
Carbon loss
Sequestered carbon
oil sands.

Presentation Type: Symposium Presentation
Session: SY07
Location: Hall C/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 9:15 AM
Number: SY07004
Abstract ID:429
Candidate for Awards:None