The aim of the study was to compare the effect of windthrow treatments established after the windstorm in 2004 on the activity of enzyme dehydrogenase (DHA) in forest topsoils. We also focused on the effect of the recent windthrow (May 2014) on the DHA in topsoil. Soil samples were collected in July 2014 from four sites in the Tatra National Park: EXT -tree trunks and wood debris extracted after the windstorm in 2004, NEX -area left for self-regeneration after the windstorm in 2004, REX -tree trunks and wood debris extracted after the windstorm (May 2014), REN -Norway spruce stand set as a control plot. We measured pH, dry weight %, soil organic matter (SOM), carbon content in microbial biomass (C bio ) and DHA. Dehydrogenase activity at studied plots was the lowest at the EXT plot and the highest values were measured at the REN plot. DHA at NEX was similar to REN suggesting comparable ecological conditions at these plots comparing to EXT. Carbon content in microbial biomass at plots reflected intensity of dehydrogenase activity in sequence EXT < REX < NEX < REN.

The formation and quality of soil organic matter (SOM) highly depends on the input of organic material and microbial enzymatic activities. Soil extractions with specific nonpolar and polar extractives can be used to identify qualitative changes in SOM. The aim of this paper was to understand the correlations among microbial enzymatic activity and specific organic fractions in acidic spruce forest soil. Klason lignin (KL), acid soluble lignin (ASL), holocellulose (HC), SOM content, and potential enzymatic activity (FDA and phosphatase) was measured and analyzed. We sampled Dystric Cambisol of forest spruce stands (Picea abies) in Tatra National Park (Slovakia). The SOM fractions were determined gravimetrically based on their extractivity in nonpolar (dichloromethane (DME)) and polar (acetone (AE), ethanol (EE), water (WE)) solvents Total extractives content was 0.079% and nonpolar extractives 0.036%. The mean amount of polar extractives tented to increase in the order EE<AE<WE. The total lignin content was determined to be 1.079% and HC 0.774%. FDA negatively correlated with KL (r=-0.873 p<0.05) and DME (r=-0.913 p<0.05). Phosphatase positively correlated with WE (r=0.972 p<0.01) and KL (r=0.957 p<0.01).

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There has been much more damage to forests in the Slovak Republic in the second half of the 20th century than to other European countries. Forested mountain massifs have become a filter of industrial and transportation emissions from abroad, as well as from domestic origins. There are not only acidic deposits of sulphur and heavy metals present in forest soils, but other additional environmental problems, such as climate change, storms, fires, floods, droughts, are worsening the situation. Therefore, forest terrestrial ecosystems are becoming more vulnerable due to changes in natural and environmental conditions. In the High Tatra Mountains in Slovakia, which are protected as a national park, four internationally monitored localities were established after the windthrow disaster in 2004 and fire in 2005: REF, with intact forest; EXT, with extracted wood mass; NEX, with non-extracted wood mass; and FIR, the burnt locality. Soils from these localities were microbiologically analysed with special attention to fungi. Bacterial microbiota detected by high-throughput sequencing showed the prevalence of the genera Acidothermus, Mycobacterium, and Nocardia, and a very low presence of the genera Acidibacter, Burkholderia-Paraburkholderia, Optitus and the uncultured genus Desulfurellaceae H16 in the soil sample from the burnt locality when compared with the unburned sites. Additionally, soil mycocoenoses showed a low similarity between the locality with an intact forest ecosystem and the localities with extracted (REF–EXT) and non-extracted (REF–NEX) wood mass. There was no similarity with the burnt locality (FIR), where heat-resistant fungi dominated. It was shown that the windthrow disaster and subsequent extraction or non-extraction of wood mass did not affect the soil microbial communities or their development. On the other hand, the influence of fire was significant.