Impacts of soil conditions and light availability on natural regeneration of Norway spruce Picea abies (L.) H. Karst. in low-elevation mountain forests

& Key message Natural regeneration of P. abies (L.) H. Karst. may reach high densities in lower mountain elevations. The highest densities were found in sites with moderate light availability, with low pH, and not near the riverbank. However, age-height classes differed in the predicted magnitude of response, but were consistent in response directions. Mosses and understory species typical of coniferous forests were positively correlated with regeneration density. & Context Norway spruce Picea abies (L.) H. Karst. in Central Europe is at risk under climate change scenarios, particularly in mountain regions. Little is known about the impact of environmental factors on the natural regeneration of P. abies in lowelevation mountain forests. & Aims We aimed to assess impacts of distance from the riverbank, soil pH, and light availability on natural P. abies regeneration. We hypothesized that (1) natural P. abiesregeneration would depend on light availability and soil pH and (2) there are understory plant species which may indicate the microsites suitable for natural regeneration of P. abies. & Methods The study was conducted in the Stołowe Mountains National Park (SW Poland, 600–800 m a.s.l.). We established 160 study plots (25 m2 ) for natural regeneration, light availability, soil pH, and understory vegetation assessment

Białowieża Forest as a biodiversity hotspot

Białowieża Forest (BF) is widely known for its outstanding natural values. The debate about the management/protection model, able to maintain all relevant values of BF on a sustainable basis, has a very long history. Currently, the main role in this debate is played by groups and organizations claiming that the major threat for the biological richness of BF is related to local forest management. In this paper, an attempt is made to verify this thesis. The extensive literature research reveals that vascular plants are one of the most threatened (and best documented) groups of organisms occurring in BF. It was found, for example, that in case of Serratulo−Pinetum (one of the most important woodland community type occurring in BF) the floristic diversity declines at the rate 0.6 species per year. However, similar situation concerns many other groups of species (e.g. lichens) as well. The recession of many species does not take place in the managed part of the BF only. This problem concerns also the areas which, since a long time already, have been subjected to the strict protection, like the ‘Strict Reserve' of the Białowieża National Park (comprising ca. 7% of the BF, under strict protection since ca. 100 years). Several factors and agents responsible for the general deterioration of natural values of BF were identified. Among other things, many authors underline the negative impacts of natural, successional processes taking part in areas which were ‘liberated' from the direct human impacts. Such processes are a direct cause of loss among many herbaceous species, particularly helio− and termophilous plants. Another important reasons for decreasing trends in many important elements of the local biodiversity are: strong reduction of open and semi−open areas (disappearance of the so called ‘cultural landscapes'), climate change, air pollution, deer overabundance, compositional impoverishment of many tree stands, invasive species of plants and animals. In conclusion, there are many factors responsible for decreasing diversity of BF and most of them have nothing to do with the local forest management. To preserve possibly high levels of the natural values of BF for future generations, a wise and complex conservation strategy is needed. As many other similar examples from different places over the world clearly show, the core element of such a strategy should be the principle of active management approach and not the out of action principle of ‘doing nothing'

Wpływ trzebieży na zróżnicowanie strukturalne drzewostanów sosnowych

The impact of two different kinds of thinning on structural diversity of pure, even−aged Scots pine stand, is analysed. The real thinning, performed in the field, is compared with simulated computer thinning. Both thinnings make use of the same set of future (elite) trees, but differ in respect to method of marking of trees for removing. To determine the impact of thinning mode on stand structure, the overall diameter distributions, as well as some structural indices (diameter differentiation, dominance index, contagion index), before and after thinnings, are analysed and compared

Tree biogroups in natural forests: was prof. Włoczewski right?

The contagion index [Gadow i in. 1998] is used to analyse a spatial pattern of trees in a natural forest stand occurring on a permanent study plot, located in a compartment 319 of the Białowieża National Park. By means of this index it is found that at a small spatial scale, the random occurrence of trees is a dominating mode of tree spatial pattern. At the same time, the share of trees forming biogroups is estimated to ca. 25% (at average). The results are compared with similar analysis performed by means of the Donnelly index and the Ripley's K function