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

Abstract

The major environmental gradients underlying plant species distribution were outlined in two climatically and biogeographically contrasting mires: a Swedish bog in the boreo-nemoral zone, and an Italian bog in the south-eastern Alps. Data on mire morphology, surface hydrology, floristic composition, peat chemistry and pore-water chemistry were collected along transects from the mire margin (i.e., the outer portion of the mire in contact with the surrounding mineral soil) towards the mire expanse (i.e., the inner portion of the mire). The delimitation and the extent of the minerotrophic mire margin were related to the steepness of the lateral mire slope which, in turns, controls the direction of surface water flow. The mineral soil water limit was mirrored in geochemical variables such as pH, alkalinity, Ca 2+ , Mg 2+ , Al 3+ , Mn 2+ , and SiO 2 concentrations in pore-water, as well as Ca, Al, Fe, N and P contents in surface peat. Depending on regional requirements of plant species, different species were useful as fen limit indicators at the two sites. The main environmental factors affecting distribution of habitat types and plant species in the two mires were the acidity-alkalinity gradient, and the gradient in depth to the water table. The mire margin -mire expanse gradient corresponds to a complex gradient mainly reflected in a differentiation of vegetation structure in relation to the aeration of the peat substrate.

Fighting carbon loss of degraded peatlands by jump-starting ecosystem functioning with ecological restoration

“…As the average water table level could be re-established and maintained for 10 years, restoration of studied peatlands was successful in regaining the single most important condition needed for further recovery of ecosystem. Together with water table level, changes of pore water chemistry may influence peatland community composition and peatland functions (Tahvanainen et al 2002;Price et al 2005;Bragazza et al 2005). Our results show that differences between Pristine and Drained sites in chemistry are significant still after several decades.…”

The Essential Role of the Lagg in Raised Bog Function and Restoration: A Review

“…Calcium is thus a useful indicator of the lagg transition. Other ions that have been found in higher concentrations in the lagg than the bog itself, and which may be useful indicators of the mineral soil water limit, include sodium, magnesium, aluminum, manganese, and silicon dioxide (Bragazza and Gerdol 1999;Tahvanainen et al 2002;Bragazza et al 2005).…”

“…Several studies have investigated the poor-rich gradient in peatlands, whether between separate fen and bog sites (Glaser 1992;de Mars and Wassen 1999;Tahvanainen et al 2002;Hájková and Hájek 2004) or along the "mire marginmire expanse" gradient within a particular bog landscape unit (e.g., Sjörs 1950;Malmer 1986;Bragazza et al 2005;Sottocornola et al 2009). Most commonly, these studies attempt to isolate the key influences on plant species composition, such as depth to water table, acidity-alkalinity, and fertility (Bragazza et al 2005).…”

“…Most commonly, these studies attempt to isolate the key influences on plant species composition, such as depth to water table, acidity-alkalinity, and fertility (Bragazza et al 2005). Field researchers examining the transition from bog center to margin rarely extend beyond the mire margin into the surrounding minerotrophic ecosystem (e.g., forest), and therefore tend to ignore the variable chemical composition of runoff from the adjacent landscape.…”

Importance of water level dynamics for vegetation patterns in a natural percolation mire (Rospuda fen, NE Poland)

“…Recently, some authors (e.g. Hájková & Hájek, 2004;Bragazza et al, 2005) underlined the interplay of the poorrich gradient with the hydrological gradient as the major mechanism explaining the diversity of mire vegetation.…”