Keywords: wetland fi re, peat fi re, fen, wildfi re.
Abstract:Fire has considerable impact on vegetation and organic soils properties. As we observed that the differences between vegetation of burnt and unburnt areas on the rich fen are visible 11 years after the fi re, we assumed that the post-fi re changes are long lasting, yet limited exclusively to the burnt areas. In order to check this hypothesis we studied spatial differentiation of physical and chemical properties of soils, and productivity capacities of burnt and unburnt areas in the fen in Biebrza National Park. We took soil samples from the neighboring burnt and unburnt areas, from the depth of 0-30 cm and 30-50 cm. We analyzed 21 parameters of the soils including: pH, ash content, moisture, bulk density, exchangeable K, Na, Ca, available P, N-NH 4 + , N-NO 3 -, total N, C, K, Na, Ca, Mg, Fe, P; and calculated C:N, C:P ratios. Surface layer of the burnt soils differed signifi cantly from the unburnt soils in respect of 17 out of 21 parameters. The most pronounced difference was observed for available phosphorous (on average 6 times higher for the burnt soils). The differences in the deeper layer were mostly insignifi cant. The burnt areas were also characterized by twofold higher plant productivity than recorded for the unburnt areas. The infl uence of fi re on peaty soils was long lasting but mostly limited to the surface layer of the soils. In the case of particular soil features, the post-fi re differences were modifi ed by advanced muck formation (moorshing) processes in the unburnt areas. Since the fi re led to long lasting increase of fertility, the recovery of fen vegetation is unlikely.Unauthenticated Download Date | 5/11/18 2:35 PM 12 M. Sulwiński, M. Mętrak, M. Suska-Malawska of burnt soils. The duration of these changes depends on i.e. the amount and chemical composition of ashes. Elements released from peat and plant biomass during the fi re may be lost via volatilization (e.g. C, N, S) or with ashes transported with smoke by convection forces. After the fi re, remaining ashes can be removed by wind, water runoff, leaching downward soil profi le or by plant uptake. They may be also transformed into insoluble compounds or remain in exchangeable form (Neary et al. 1999, Certini 2005, Dikici and Yilmaz 2006, Qian et al. 2009a, Qian et al. 2009b.To the typical post-fi re changes of soils we may include: increase in pH, decrease in total amounts of nitrogen and carbon, and higher availability of P, K, Ca and Mg. The ranges of these alterations differ, depending on the type of soil and the fi re intensity (Neary et al. 1999, Marcos et al. 2007, Certini 2005, Ketterings and Bigham 2000, Arocena and Opio 2003, Dikici and Yilmaz 2006. Though the effects of fi re on mineral soils are well examined, there is not enough information on its infl uences on physical and chemical properties, especially long-term ones, of peaty soils (Dikici and Yilmaz 2006, Wang et al. 2015). Hence, we present a study carried out in the area of a burnt-out fen, 11 years a...