Effects of mineral and nutrient input on mire bio‐geochemistry in two geographical regions

Abstract

Summary 1We assessed the role of climatic conditions and the effects of different, long-term atmospheric depositions in controlling the mineral and nutrient contents in pore-water, surface peat and in living Sphagna at a boreo-nemoral mire in Sweden and an alpine mire in Italy. 2 The terrestrial contribution of Ca 2+ , Mg 2+ and in bulk precipitation was much greater at the Italian mire, in accordance with the different bedrock in the region and the higher level of atmospheric pollution. 3 At both mires, the contribution of bulk precipitation to the concentration of major ions in mire pore-water was much greater in the ombrotrophic than in the minerotrophic part, because of the raised morphology of the mires, which limited the inflow of mineral soil water to the margins. The only ions strongly depleted in mire pore-water compared with precipitation were K + , and and these were therefore limiting to plant growth. 4 Higher concentration in pore-water at the Swedish mire, which experienced lower atmospheric inputs of sulphate, was probably caused by oxidative processes during a long dry period in the summer before sampling. 5 Higher rates of , , as well as atmospheric inputs at the Italian mire were reflected in significantly higher N and, partly, S concentrations in ombrotrophic Sphagna. Higher concentration in pore-water at the Italian mire was associated with a lower N retention coefficient of the ombrotrophic Sphagnum plants, suggesting a reduced nitrogen filtering ability of the moss layer.

The Geochemistry of Ombrotrophic Sphagnum Species Growing in Different Microhabitats Of Eight German and Belgian Peat Bogs and the Regional Atmospheric Deposition

“…Yet, the Sphagnum concentration values are thought to be quite reasonable because of the huge amount of samples investigated, whereas deposition monitoring data are restricted to some solitary monitoring sites only, which might not reflect reasonably well the atmospheric deposition into the peat bogs studied. However, Proctor (1992) and Bragazza et al (2003) found that the bulk precipitation data did not sufficiently explain the cation contents in surface or pore-waters of ombrotrophic peat bogs. They con- Atmospheric deposition [kg ha -1 a -1 ]…”

Multiple gradients in mire vegetation: a comparison of a Swedish and an Italian bog

“…Indeed, at both mires pH, alkalinity, Ca 2+ , Mg 2+ , Al 3+ , Mn 2+ , and SiO 2 concentrations in pore-water were higher in the lagg fen than in the expanse (Shotyk 1988;Gerdol 1995;Vitt et al 1995;Reeve et al 1996;Mullen et al 2000;Tahvanainen et al 2002). Geochemical differences in pore-water between the Swedish and the Italian mire are the consequence of different environmental conditions at the two sites concerning atmospheric chemistry and climate (Bragazza et al 2003). In particular, higher values of pH and Mg 2+ in pore-water at the Italian mire (P < 0.05) are related to the higher deposition of alkaline dust on Wölfl Moor in accordance with the higher pH of precipitation at Wölfl Moor (pH = 5.19, Tait and Thaler 2000), compared to Ryggmossen (pH = 4.64, Swedish Environmental Research Institute, unpublished data).…”

Long-term nitrogen deposition increases phosphorus limitation of bryophytes in an ombrotrophic bog

“…Although some species of bryophytes take up nutrients from the substrate upon which they are growing (Ayres et al 2006), most obtain much of their nutritional requirements by intercepting ions from rainwater. They are therefore sensitive indicators of their environment (Turner et al 2001) that have been used to predict past levels of atmospheric deposition (Bragazza et al 2003(Bragazza et al , 2005 and closely reflect the level of external pollutant loads (Turner et al 2001). As a consequence there has been considerable interest in the potential use of bryophyte responses as bio-indicators of N deposition in a range of ecosystems (Pitcairn and Fowler 1995;Gidman et al 2006).…”