Manipulation of Snow in Small Headwater Catchments at Storgama, Norway: Effects on Leaching of Inorganic Nitrogen

Abstract

We have manipulated the winter-time soil temperature regime of small headwater catchments in a montane heathland area of southern Norway to study the possible effects on concentrations and fluxes of inorganic nitrogen in runoff. The experiments included extra insulation of soils in two catchments to prevent subzero temperatures during winter, and removal of snow in two other catchments to promote soil frost. Increased soil temperatures during winter increased the springtime concentrations and fluxes of ammonium (NH4) and nitrate (NO3) in runoff. By contrast, snow removal with development of significant soil frost showed no systematic effects on mean concentrations or fluxes of inorganic N. The results from our experiments suggest that warmer soils during winter caused by exceptionally mild winters, or alternatively a heavy snowpack, imply a greater risk for inorganic N leaching in this region than a possible increase of soil frost events because of reduced snow cover.

Litter decomposition rate and soil organic matter quality in a patchwork heathland of southern Norway

“…The relatively small amount of water extracted by centrifugation limited the number of possible analyses, preventing N speciation. TDN therefore included both organic N and inorganic N, the latter amounting to 25-50 % of TDN in soil water from southern Norway Kaste et al, 2008).…”

Mountain soils under a changing climate and land-use

“…In a recent snow manipulation experiment in the Norwegian mountains, addition of snow induced a soil warming and resulted in increased fluxes of inorganic N during spring runoff, whereas snow removal causing soil frost had no systematic effect (Kaste et al 2008). In contrast, neither the soil warming nor soil frost in winter had a pronounced effect on concentrations and fluxes of dissolved organic carbon (DOC).…”

Consequence of altered nitrogen cycles in the coupled human and ecological system under changing climate: The need for long-term and site-based research

“…In mountainous and northern regions, soil temperatures and ecosystem respiration rates tend to be higher in winters with high amounts of snowfall than in winters with less or no snow (Monson et al 2006). On the other hand, experimental snow manipulation at a mountain site in Norway indicated that no increase of inorganic N fluxes was associated with snow removal (Kaste et al 2008), suggesting that the effects of decreased snow on the N cycle varies among locations. Coherent patterns of variation in NO 3 -leaching are sometimes evident over large spatial scales and across catchments covering wide altitudinal gradients and land-use classes (e.g., Rogora et al 2008;Evans et al 2010).…”

“…Lake manipulation experiments have been undertaken in Canada, Norway, the USA, and Finland (e.g., Carpenter et al 2001;Harris et al 2014). There have also been a number of snow manipulation experiments in the USA, Norway, and Germany (e.g., Kaste et al 2008;Wipf and Rixen 2010). While contributing to our current understanding of N cycling in ecosystems, they also reveal significant gaps in knowledge which will require a continued commitment to long-term research and a broadening of international perspectives to address.…”