Odnowienie naturalne drzew w Puszczy Białowieskiej

Since several years already, a massive infestation of bark beetle has taken place in the Białowieża Forest, decimating a local Norway spruce population. In consequence, many open areas appeared, practically deprived of trees and other forest vegetation. The existence of such areas has a very negative impact on multiple values of the Białowieża Forest: natural, social, economical and landscape−aesthetic values. The local forest administration prepared a strategy aimed at active restoration of diverse woodland communities typical for the Białowieża Forest in all places, where bark beetle infestation wiped up the spruce stands. Those plans were criticized by representatives of the environmental organizations who blamed the foresters for transforming the Białowieża Forest into ‘plantation’ and claiming that such measures are inconsistent with the existing forest management and protection plan. The postulate of environmentalists is that the recovery of woodland communities should proceed completely naturally. Taking into account the above mentioned controversies, in this paper we examine the issue of natural regeneration in the Białowieża Forest in detail. In particular, we try to determine to which extent this method of forest reproduction enables re−establishment of compositionally diverse woodland communities, distinguished by a high level of biological diversity and able to provide a wide range of commodities and benefits important for today’s society. Based on an extensive literature review we show that a combination of different (abiotic and biotic) factors, influencing establishment and subsequent growth of seedlings and saplings in the Białowieża Forest has long been strongly unfavorable for many tree species. In this regard, one should particularly emphasize the negative role of large herbivores, especially red deer, which is present in the Białowieża Forest since the end of 19th century, when it became a private hunting ground for Russian tzars. The devastating effect of deer browsing on natural regeneration is a well−documented phenomenon and widely recognized problem in the forestry practice. The fencing of young forest generation against game pressure is an indispensable measure, needed to secure the continuous existence of several tree species (first of all those palatable and vulnerable to browsing). Very strong arguments for an active approach to the described problem delivers also a long−term study on natural forest dynamics conducted since 1936. It shows that under conditions of strict protection the regeneration capacity of the Białowieża tree species is very variable. These differences lead to the compositional simplification and impoverishment of many tree stands, with numerous negative consequences for local biodiversity. We underline that an active management strategy is a basic prerequisite for maintaining a diverse character of the Białowieża stands and their ability to provide all important ecosystem services on a sustainable basis. Such a strategy should include, beside of the phase of establishment, also the subsequent developmental stages of new forest generations. The general goal of such a strategy should be to secure a possibly high diversity of tree composition and to enable the development of tree species representing a full range of life−history strategies and playing different successional roles: from typical pioneer species, through intermediate, to climax species.