Search

Nowadays, the large-scale disturbance and subsequent temporary deforestation of mountain forests are widely discussed phenomena. In this study, we built both a logistic regression model (LRM) and a generalised additive model (GAM), in order to understand the drivers of deforestation after the Elisabeth windstorm (2004) in the Central Low Tatras, Slovakia. A set of topographic and biotic characteristics was selected as explanatory variables, while the presence of deforestation was a response variable. The results show that the most prone to windstorm-driven damage are forests growing at a high elevation, in the ridge’s surroundings, and on gentle slopes exposed to the wind during the disturbance. Moreover, the stands with a high proportion of Norway spruce and with medium-diameter trees, which are under forest management, were identified as more vulnerable. Additionally, both models were used to identify those stands, which would be most susceptible to damage by future windstorms. According to its explanatory power and building efficiency, we propose using of LRM rather than GAM in similar large-scale studies. The addressed methods can be used in local forest management, as scientifically based decision-making appears to be crucial for maintaining mountain forests resistant to gusty winds, as well as other disturbing agents.

The aim of this study was the evaluation of the spruce natural regeneration growth and development in Modrava and Plechý areas, which represent the first and late bark beetle attack areas. Study was done on 13 permanent research plots, partly with vital tree layer and canopy cover and partly characteristic by open or none canopy, due to bark beetle attack. Actually amount of this regeneration is sufficient (average over 12,000 pcs/ha in the living stands and almost half of this amount in the declined stands) on the both types of plots. Faster growth is usually on the declined plots, with saplings larger amount and height increments, in the higher height classes. Particular interest was aimed to the microhabitat conditions, especially herbal cover influence. There were statistically important differences in the amounts and height growth of the first height class on the different microhabitats. As the most sufficient for the seedlings occurrence appeared to be the dead wood and the least suitable were fern and grasses. For the height growth the least suitable was vital tree foot with litter cover. The results indicate, that declined stands, without vital mature trees and without seed source, will likely develop into more or less even-aged forest.

Humus forms dynamics and characteristics of different forest sites were studied in the area of Smrčina Mt. in the Šumava National Park territory. The study was performed in vital Norway spruce forest, dead Norway spruce forest (bark beetle Ips typographus infestation) and on a clear-cut area (site conditions were comparable for all three plots). The amount of surface organic matter was not affected by forest decline or by clear-cut (95.5 t/ha, 73.1 t/ha and 100.2 t/ha, respectively), pH being comparable (between 2.3 and 3.2 pH KCl). A slight favourable effect of grass litter on pH increase was obvious; higher leaching of bases occurred in lower horizons. Nitrogen losses were detected from the L + F horizons, falling from 1.93-1.83% (living stand) to 1.73-1.83% (clear-cut area). Higher ammonia production was documented in substrates (F and H horizons) from the living stand (from 263 and 103 mg/kg before incubation to 610 and 248 mg/kg after incubation - nitrogen content in ammonia form), and higher nitrification rates (nitrogen content in nitrate form) were recorded on the clear-cut area (103 and 80 mg/kg to 153 and 87 mg/kg) and especially in the dead stand (160 and 93 mg/kg to 216 and 139 mg/kg). Respective values for the living stand increased from 52 and 61 mg/kg to 119 and 84 mg/kg. Respiration activity, both potential and basic, was more balanced, indicating more intensive dynamics in the case of dead stand and clear-cut area.

Changes in the herb and moss layers of mountain spruce (Picea abies (L.) Karst.) forests after bark beetle (Ips typographus (L.)) outbreak were compared with and without forestry intervention. The study area is situated in the Šumava National Park (Czech Republic, Central Europe), where an extensive bark beetle outbreak occurred in the 1990s. Parts of forests were left without interventions, while salvage logging was applied in other areas. Altogether, 18 permanent research plots were established in: (1) climax stands with completely dead canopy, (2) climax stands where salvage logging was applied (clearcuts), and (3) waterlogged stands with only partly dead canopy. Vegetation composition of the ground layer and species numbers were evaluated in 1997 and 2002. The effect of salvage logging on vegetation was greater than that of the bark beetle outbreak itself. Forest herb species and partly also bryophytes survived relatively well under untouched dead canopy. The fewest changes occurred under the partly dead canopy in waterlogged forests. The herb layer expanded in clearcuts originated due to salvage logging, being dominated by grasses. Bryophytes were more susceptible to logging than herbs; their cover in clearcuts was markedly lower and composition changed towards pioneer species. The results show that a natural succession of mountain spruce forests after a bark beetle outbreak, if left without interventions, will probably avoid a pioneer stage and direct recovery of the forests will be possible. Salvage logging had negative effects on species composition of the spruce forests, delayed the forest recovery, and should not be permitted in the national park. [Copyright &y& Elsevier]