Explaining the large-scale diversity of soil organisms that drive biogeochemical processes-and their responses to environmental change-is critical. However, identifying consistent drivers of belowground diversity and abundance for some soil organisms at large spatial scales remains problematic. Here we investigate a major guild, the ectomycorrhizal fungi, across European forests at a spatial scale and resolution that is-to our knowledge-unprecedented, to explore key biotic and abiotic predictors of ectomycorrhizal diversity and to identify dominant responses and thresholds for change across complex environmental gradients. We show the effect of 38 host, environment, climate and geographical variables on ectomycorrhizal diversity, and define thresholds of community change for key variables. We quantify host specificity and reveal plasticity in functional traits involved in soil foraging across gradients. We conclude that environmental and host factors explain most of the variation in ectomycorrhizal diversity, that the environmental thresholds used as major ecosystem assessment tools need adjustment and that the importance of belowground specificity and plasticity has previously been underappreciated.

Soil and moisture conditions are key factors for vegetation establishment in reclamations of lands after mining. These factors play a more important role if the area is under extreme environmental conditions. Záhorská lowland belongs to the most extreme areas in Slovakia and it is characterized by drought and warm climate.Besides high average temperature and precipitation deficit this area is negatively affected by wind. Light sandy soil is damaged by wind erosion (Serdel 1973). These factors affect artificial forest regeneration and reclamation. Therefore it is needful to draw up new or modified procedures for the improvement of soil moisture conditions. The aims of these procedures should be to increase planting stock survival and field performance after planting.In the last years, a new generation of hydrogels was developed, highly cross-linked polyacrylamides with 40% of the amides hydrolyzed to carboxylic groups. According to Bouranis et al. (1995) these hydrogels are able to absorb and store water up to 400 times their own weight, and consequently, reduce water stress for the trees. Hydrogels of STOCKOSORB belong to these new hydrogels.Different hydrogel fractions are used commensurate with an application -STOCKOSORB Powder (fraction size < 0.2 mm, for the root system protection during planting, handling, storing and transporting). STOCKOSORB AGRO and MICRO (0.2-0.3 mm) are used for direct application to planting holes before planting. These hydrogels are frequently used for afforestation in semi-arid areas (Roldan et al. 1996;Tognetti et al. 1997). On the other hand, little information is available about the use of these hydrogels under environmental conditions in Central Europe.The aim of this study was to determine the effect of hydrogel STOCKOSORB application on the survival and growth of pine (Pinus sylvestris L.) seedlings in the reclamation of a sand pit. MATERIAL AND METHODS Pieskovňa I -Plantation 2002On In this study results of hydrogel application in reclamations are presented. The application of hydrogel affected the survival of pine seedlings during two vegetation periods after planting. Double application of STOCKOSORB AGRO (gel) on the root system after lifting caused an about 19% higher survival rate compared to control variants. The application of 7 g/planting hole of STOCKOSORB MICRO granules caused overdosage and plant mortality. The application of hydrogel granules is simple but it is very complicated not to cause the overdosage because of the very high swelling capacity of hydrogel. Research should be carried out to determine suitable hydrogel application rates for different environmental conditions and tree species. To design a technology with regard to the economic effectiveness of application will be a very important task.

Spatially explicit knowledge of recent and past soil organic carbon (SOC) stocks in forests will improve our understanding of the effect of human- and non-human-induced changes on forest C fluxes. For SOC accounting, a minimum detectable difference must be defined in order to adequately determine temporal changes and spatial differences in SOC. This requires sufficiently detailed data to predict SOC stocks at appropriate scales within the required accuracy so that only significant changes are accounted for. When designing sampling campaigns, taking into account factors influencing SOC spatial and temporal distribution (such as soil type, topography, climate and vegetation) are needed to optimise sampling depths and numbers of samples, thereby ensuring that samples accurately reflect the distribution of SOC at a site. Furthermore, the appropriate scales related to the research question need to be defined: profile, plot, forests, catchment, national or wider. Scaling up SOC stocks from point sample to landscape unit is challenging, and thus requires reliable baseline data. Knowledge of the associated uncertainties related to SOC measures at each particular scale and how to reduce them is crucial for assessing SOC stocks with the highest possible accuracy at each scale. This review identifies where potential sources of errors and uncertainties related to forest SOC stock estimation occur at five different scales-sample, profile, plot, landscape/regional and European. Recommendations are also provided on how to reduce forest SOC uncertainties and increase efficiency of SOC assessment at each scale.

The research site “Vrchslatina” was established in the spring of 2009 with the aim of studying production processes and the structure of net primary productivity in young forest stands. The beech and spruce stands grown at the site were selected because they originated from natural regeneration and are nearly of the same age. In 2009, we established 5 research plots in each stand with the aim of measuring basic tree characteristics. Moreover, we excavated entire trees to construct allometric relations for the specific tree compartments. In the consecutive years (2010, 2011 and 2012), we also included grass communities dominated by Calamagrostis epigejos in our studies. Besides studying production processes of all tree compartments (i.e. for trees: foliages, branches, stem, coarse and fine roots, for grasses and herbs: below- and above-ground parts), we monitored several atmospheric characteristics, followed by soil characteristics and eventually added a measurement of soil respiration. The results indicated that forest stands (even though they were in their initial growth stages) sequestrated much more carbon than the grass communities. Moreover, we proved the considerable influence of climatic conditions (especially the sum of precipitation) in the particular years for net primary productivity.

We focus on the analysis of sap flow and stem circumference changes in European beech (Fagus sylvatica, L.) in relation to available soil water and weather conditions during the growing seasons 2012 and 2013. The objective was to examine how soil water potential affects growth and transpiration of a mature beech stand situated at the lower distributional limit of beech in Slovakia. To be able to evaluate beech response to soil water shortage, we irrigated a group of 6 trees during the period of pronounced drought, while the control group of other 6 trees remained exposed to actual weather conditions. Mean air temperatures of both seasons were considerably above the long-term average and the temporal pattern of precipitation differed between the years. During the whole growing season 2012, beech samples transpired an average volume of 6.9 m3 of water in the control and 7.7 m3 in the irrigated group. A slightly higher average volume was found in the growing season 2013 under both treatments (7.7 m3 in control and 10.5 m3 in irrigated trees). In the drought period 2012, when the irrigation experiment was commenced, the sap flow in the control group was reduced by 30% as compared with the irrigated group. In 2013, a 38.1% difference in sap flow was observed between the groups. Sap flow in the non-irrigated trees decreased with reducing soil moisture, and ceased at soil water potential -0.6 MPa. In both treatments and years, we found significant correlations between hourly sap flow and investigated weather variables. A reduction in stem circumferences of the control trees, which was observed during stem shrinkage phase, was up to 19% in 2012 and 10% in 2013. We conclude that stem circumference shrinkage during the peak of soil drought was induced by the cessation in the sap flow process.