Białowieża Forest: what it used to be, what it is now and what we want it to be in the future

For many centuries, management of the Białowieża Forest has not focused on timber production. Therefore, despite hunting, grazing by domestic animals and sporadic cutting of valuable trees the forest has retained its natural character. After World War I, a small part of the Białowieża Forest was protected as a reserve that later became a national park, while the remainder was managed for timber. After World War II, the protection status of the Polish part of the Białowieża Forest was maintained with the national park at the center surrounded by managed stands. During the last few decades, the national park was enlarged and new reserves were established. However, the majority of the Białowieża Forest is still managed for timber. The forest management has been sustainable for decades and in the last few years logging has even been strongly reduced, to a level comparable with some national parks. In recent years the Białowieża Forest, like many areas in Central Europe, has been plagued by a high spruce mortality caused by bark beetles. In managed forests, cutting the infested spruces and removing them from the forest is a standard practice aimed at reducing the growth rate of the bark beetle population. This, however, raises the question of whether we expect the Białowieża Forest to remain a managed forest, in which case the fight against bark beetles would be justified, or whether we want it to be converted into a large national park? In the latter case, cutting trees to fight bark beetles would be inconsistent with the aim of conservation. Recent discussions concerning the Białowieża Forest have been dominated by two different ideologies for nature protection. The first approach aims at protecting nature to make it sustainable, beautiful and healthy. In the second approach, protecting nature is achieved by removing any direct human influence, even if the resulting natural environment does not meet our expectations.

Indikatoren zur Schätzung des Trockenheitsrisikos in Buchen- und Fichtenwäldern

Indicators for quantitative assessment of drought risks in beech and Norway spruce forests The application of climate models to forecast future forest development asks for quantitative drought-response relationships, with the term “drought” first needing a definition. The long-term data series of an intercantonal forest observation program allowed to test various drought indicators, to compare them and to derive quantitative relationships for beech and Norway spruce. For basal area increment of both tree species indicators of the site water balance (SWB) performed best. For beech mortality site water balance and several indicators basing on the ratio between actual and potential evapo-transpiration (ETa/ETp) were equivalent, whereas for spruce mortality ETa/ETp during the first 80 days of the season was the best indicator. With these indicators the average drought related growth reduction after 2003 – a year with extreme drought – was estimated to amount to 32% for beech and 37% for Norway spruce. Mortality of Norway spruce increased by 130%, whereas the estimates for the increase of beech mortality vary between 54 and 110%, depending on the indicator. The observed quantitative relationships for growth were applied to map drought responses of growth for Switzerland. The maps clearly show the dry regions of Switzerland (northern Switzerland, southern Jura foothills, Lemanic region, Valais and Rhine valley around Chur), where basal area increment of beech and Norway spruce was reduced by more than 40%.

Impact of selected stand characteristics on the occurrence of the bark beetle Ips typographus (L.) in the Beskid Żywiecki Mountains

Recently, Norway spruce stands in Beskid Żywiecki (Western Carpathians) have been plagued by bark beetle outbreak affecting an extensive area over a large range of altitudes. Georeferenced data (2356 records) from 2009-2011 of the volume of felled spruces showing insect infestation in forest sub-compartments were analysed with respect to selected site and stand characteristics. The infestation intensity varied between individual parts of the examined area. Spruce mortality, recorded evenly across all slope expositions, was higher in the zones 800 m - 1000 m and above 1000 m than in the zone below 800 m. The infestation intensity increased slightly with spruce representation in the stands and was higher in stands older than 80 years. There was no clear correlation between spruce mortality and site quality. However, in areas with more diverse and fertile sites mortality was lower. In overall, the results obtained in this study are in line with previous knowledge on the subject, but patterns describing bark beetle preferences in infested areas appear to be less pronounced than those found in earlier publications. Risk assessment and current planning of forest protection measures in stands affected by bark beetle outbreaks should be based on the here described characteristics of spruce susceptibility to insect infection.

A comparison of lower montane natural forest (Abies, Fagus, Picea) in Oszast Reserve and spruce monocultures in the Żywiecki Beskid and Śląski Beskid

The aim of this research was to find out what changes occurred between 1999-2009 in Oszast reserve in the volume, species composition and diameter at breast height (dbh) distribution of the forest stand, and the number and height of regeneration. The objective was to determine what would be condition of these managed lower montane multispecies forest stands (Swiss irregular shelterwood method or selection cuttings) and what role spruce would play in them if they have not been replaced by spruce monocultures. The research was conducted on three permanent circular sample plots (s.p.), each had size of 1/3 ha. Over 10 years, standing volume of the forest stand increased on s.p. 1 (from around 562 m3/ha to 649 m3/ha) and s.p. 3. (from 653 m3/ha to 660 m3/ha), while decreased on s.p. 2. (from 421 m3/ha to 378 m3/ha). The species composition, defined on the basis of volume share (averaged for the three s.p. jointly), did not undergo consistent changes. However, the relative dominance of beech over spruce was determined based on tree numbers. The average spruce mortality (averaged from three s.p.) did not exceed 10% and was slightly higher than that of beech (6%), and lower than fir mortality (15%). Nevertheless, spruce did not show any symptoms of dieback. The reasons behind its mortality were fallen trees and windbreaks. In regeneration, on the whole, beech or sycamore predominated, and the proportion of spruce and fir was small. In the future spruce and fir may even decrease further by competitive ability of dynamically regenerating beech. Abandonment of forest management to promote greater diversity of species, may favour the formation of beech monocultures, or forest stands dominated by beech, everywhere that beech is already present or will be introduced. The maintenance of stable, multispecies forest stands, with co-dominant fir, beech and spruce of native origin, requires natural or artificial regeneration of spruce and fir, manipulated to restore fir up to about 30%, and reduce spruce down to about 40%. This would be possible through the use of the Swiss irregular shelterwood method and selection system, and by continuous tending of regeneration