Are nutrient availability and acidity-alkalinity gradients related in Sphagnum-dominated peatlands?

Gradients in acidity-alkalinity and nutrient availability were studied in 2 Sphagnum-dominated peatlands on the southeastern Italian Alps. Decreasing concentrations of most mineral elements (Ca2+, Mg2+, Mn2+, Al3+ and Si4+) in pore water indicated a progressively lower influx of mineralsoil water from the slightly minerotrophic conditions in the peatland margins to ombrogenous conditions in the central part of the peatlands. This was paralleled by decreasing concentrations of ash, bulk density, Ca, Fe and, partly, Mn in the peat. The nutrient gradient, as defined by pore water concentrations of N and P, was largely independent of the acidityalkalinity gradient: NO3- and PO43- had similar concentrations throughout the gradient, whereas NH4+ concentrations increased with increasing pore-water pH. In contrast, the peat nutrient gradient coincided with the acidity-alkalinity gradient, with total concentrations of N and P decreasing from the margin to the centre. Bryophytes and vascular plants had different responses along the acidity-alkalinity gradient and the nutrient gradient. Bryophyte distribution reflected the acidity-alkalinity gradient both in pore water and in peat. Vascular plant distribution was mainly influenced by variations in nutrient availability