limiting roles of nitrogen and moisture on Sphagnum angustifolium growth over a depth to water table gradient

• Published in: Plant and soil 2016-07, Vol.404 (1-2), p.427-439
• Main Authors: Graham, Jeremy A, Dale H. Vitt
• Format: Article
• Language: English
• Subjects: biomass; Biomedical and Life Sciences; Bogs; bulk density; Climatology; Ecology; ecosystems; Fens; Growing seasons; Health aspects; Life Sciences; Limiting factors; Moisture; Moss; Mosses; Nitrogen; Nitrogen content; Nitrogen cycle; Peatlands; Plant Physiology; Plant Sciences; Plant-soil relationships; Plant-water relationships; Precipitation; Primary production; primary productivity; Regular Article; Soil moisture; Soil nitrogen; Soil Science & Conservation; Soils; Sphagnum; Sphagnum angustifolium; Water depth; Water table; Water table gradient; Water tables
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-016-2906-1

BACKGROUND AND AIMS: Boreal peatlands are projected to face numerous stressors in the future, including changes in precipitation and nitrogen cycle perturbations. Nitrogen is currently believed to be the limiting factor to peatlands of western Canada, including to Sphagnum, however new insights suggest the possibility of multiple limiting factors. METHODS: Growth, nitrogen assimilation, and annual retention of Sphagnum angustifolium, a species with a broad niche, were observed across a depth to water table gradient for three years to further understand the partitioning of key limiting factors. RESULTS: Within each year differences of linear growth were responsible for variations in net primary production (NPP), yet yearly differences of NPP were attributed to annual differences in bulk density. Sphagnum angustifolium on the wet end of the depth to water gradient is characterized as nitrogen limited with high growth and low N concentrations, compared to less growth and high N concentrations at the water limiting dry end. Of the nitrogen that is annually assimilated by S. angustifolium, approximately 1.3 g N m⁻² is lost from biomass one year subsequent to assimilation, demonstrating the rapid turnover of this nutrient. CONCLUSION: The depth to water table gradient is strongly related to many S. angustifolium growth parameters and is a pivotal mechanism in delineating limiting factors within a single complex peatland ecosystem.