The bottom layer of the reference forest was characterized by over 70% cover of P. schreberi in the moss bottom layer and the shrub understory was over 50% cover of dwarf shrubs. In contrast the spruce-Cladina forest had less than 3% cover Nutlin-3 order of P. schreberi and over 50% cover of Cladina in the bottom layer and about 18% cover of all dwarf shrubs in the understory. Soil characteristics in open spruce stands with Cladina understory were notably different than those found in neighboring spruce, pine, feathermoss forest stands within the

same area. Recurrent use of fire reduced the depth of O horizon by an average of 60% across all three forest sites. Both total N capital ( Fig. 1a) and total concentration ( Table 2) associated with the O horizon were significantly reduced by historical burning practices. Total N concentration in the O horizon decreased by about 50% where total N capital decreased by a factor of 10. Nitrogen capital values of greater than 800 kg N ha−1 exist on the reference forest stands as compared to less than 80 kg N ha−1 on the spruce-Cladina forests. Total C in the O horizon was also much lower in the spruce-Cladina forests ( Table high throughput screening assay 2 and Table 3, Fig. 1b), but not to the extent of

N. Mineral soil total C and N were not significantly different between the spruce-Cladina and reference forest stands. Total P and extractable Mg are the only other nutrients in the mineral soil that have been significantly influenced by the years of periodic burning (Fig. 2 and Fig. 3). There were no differences in total Zn or exchangeable Ca concentrations in the mineral soil of the two forest types (Table 4). Total N:P (Fig. 4) of the O horizon were low for both forest types, but were significantly higher in the spruce-Cladina forests, likely as a result of reduced N2 fixation and increased net P loss from these soils. Ionic resins buried at the interface of the O horizon and mineral soil in both forest types revealed noted differences in N turnover between the spruce-Cladina forests

and the reference forests. Averaged across the three sites, NO3−-N accumulation on ionic resins was significantly greater in the degraded lichen-spruce isothipendyl forest than that in the reference forest ( Fig. 5a). Resin adsorbed NH4+-N concentrations were notably greater in the reference forests ( Fig. 5b). Previous pollen analyses from the two sites Marrajåkkå and Marrajegge demonstrated a decline in the presence of Scots pine and juniper in conjunction with a great increase in the occurrence of fire approximately 500 and 3000 years BP, respectively (Hörnberg et al., 1999). The pollen record from Kartajauratj showed the same trend with a general decrease in the forest cover over time and the occurrence of charcoal indicates recurrent fires (Fig. 6).