Damage reduction and performance of mass trapping devices for forest protection against the spruce bark beetle, Ips typographus (Coleoptera Curculionidae Scolytinae)

? The spruce bark beetle, Ips typographus, is one of the main European forest pests, and mass trapping is probably the most common strategy applied to reduce its population density. However, the results concerning the effectiveness of this control system are often controversal, and many studies consider only the trapping performance with no attention to the damage reduction.

? During spring-summer 2005, a control program against I. typographus outbreaks was set up in NE Italy. Twenty-four spruce forests heavily infested by I. typographus were studied: six protected by pheromone slot-traps, six by horizontal trap-logs and six by standing trap-logs; six untreated stands were kept as controls. Trap-logs were baited with a pheromone specific to I. typographus and treated with insecticide. Each type of device was tested at high, medium and low density in relation to the number of trees infested during the previous year. New damage occurring in the investigated stands was later monitored for one year.

? Protected forests showed mean damage about 80% lower in 2005 than in 2004, with no statistical difference among traps, trap-logs or standing trap-logs. Instead, unprotected forests (controls) suffered damage to a similar extent in both years. Trapping devices showed no statistical differences among mean captures. Device densities showed similar results in damage reduction and insect trapping.

? The results support the hypothesis that intensive trapping performed at stand level may be useful for protecting forests against I. typographus, locally reducing population density and tree mortality.

     

Effects of forest restoration treatments on the abundance of bark beetles in Norway spruce forests of southern Finland

Restoration of protected areas in boreal forests frequently includes creating substantial volumes of dead wood. While this benefits a wide range of dead wood dependent invertebrate species, some of these are regarded as forest pests. Therefore, the risk of elevated levels of tree mortality in surrounding commercial forests must be considered. In a large-scale field experiment in southern Finland, we studied the effects of restoration treatments on the abundance of bark beetles within and in the vicinity of restored areas, in particular focusing on Ips typographus and Pityogenes chalcographus. The treatments applied to managed Norway spruce forests were controlled burning and partial harvesting combined with retaining 5, 30 or 60 m³/ha of cut down wood. We found that the abundance of bark beetles increased by both burning and harvesting with down wood retention, being highest where burning and harvesting had been combined. The actual volume of down wood retention had no significant effect. The effect of burning on the number of bark beetles along host tree boles was negative which suggests that burnt spruces provided a less suitable resource for bark beetles than unburnt dead spruces. The abundance of bark beetles along host trees also decreased with increasing volume of down wood retention. The abundance of P. chalographus was slightly elevated up to 50 m outside restored areas but the abundance was very low compared to that within the areas. The abundance of I. typographus was extremely low outside restored areas. We conclude that restoration treatments increase the abundance of bark beetles via increased availability of resources, but that the effect of burning is likely to be counteracted by decreased resource quality. Thus, burning might be the “safest” way to produce large quantities of dead wood. Furthermore, the fact that only few beetles were collected in adjacent areas suggests that restored areas pose little threat of serving as refugia in which bark beetle populations increase in sufficient numbers to attack live trees in adjacent forests. However, restoration actions repeated at consecutive years within a small area might enable the populations to grow to outbreak levels.     

Fungi associated with Ips typographus on Picea abies in southern Poland and their succession into the phloem and sapwood of beetle‐infested trees and logs

This study dealt with the species distribution and frequency of fungi associated with the bark beetle Ips typographus (Scolytidae) on spruce trees of various states of health in southern Poland. The spruce trees were assessed by their degree of defoliation and damage of their crowns and trunks after attack by I. typographus. The state of health of trees from which samples were obtained was related to varying stages of brood development of I. typographus. Fungi were isolated from phloem taken from and around insect galleries and the sapwood underneath brood systems. Samples were taken from ‘healthy‐looking’, weakened, wind‐fallen and wind‐broken trees as well as from trap trees. The mycobiota associated with I. typographus was quite diverse in respect of the number of detected species, 65 fungal taxa were obtained from the phloem of trees infested by I. typographus, and 36 taxa occurred in the sapwood underneath insect galleries. The spectrum of fungi mainly consisted of ascomycetes and anamorphic fungi. The ophiostomatoid fungi were represented by 14 species and were the most numerously represented group in all niches examined. The most frequent ophiostomatoid species were Ceratocystis polonica, Ophiostoma ainoae, O. bicolor, O. penicillatum, O. piceae and O. piceaperdum. The frequency of occurrence of ophiostomatoid fungi differed significantly between the phloem and sapwood as well as in relation to the varying states of health of the spruce trees. These quantitative differences in the mycobiota of I. typographus between spruce trees belonging to different health categories can be explained by successional patterns of fungal colonization of host tissues following attack by I. typographus. The pathogenic species C. polonica was the primary invader, occurring most frequently in the sapwood of ‘healthy‐looking’ trees. Ophiostoma bicolor, O. penicillatum and O. piceaperdum also occurred during the early stages of brood development of I. typographus on ‘healthy‐looking’ trees, but they mainly colonized the phloem. In contrast, O. ainoae, O. minuta and O. piceae likely follow the aforementioned species as secondary and tertiary invaders into the phloem and the sapwood of spruce trees.     

Persisting bark beetle outbreak indicates the unsustainability of secondary Norway spruce forests: case study from Central Europe

? Context

Secondary Norway spruce forests in the Western Beskids are among the most damaged forests in Europe. Although spruce bark beetle (Ips typographus) has been recently causing large-scale damage to these forests, our understanding of I. typographus dynamics in this environment is inadequate for evaluating forest sustainability.

? Aim

This study aims to evaluate the patterns of damage caused by I. typographus to spruce forests with compromised ecological stability.

? Methods

Forest infestation by I. typographus was inferred from sanitary felling data collected from 1998 to 2004. Stand and site data were obtained from forest management plans. Spatial-dependence analysis, ordinary kriging and neural network-based regression modelling were used to investigate the patterns of infestation and the casual relationships in the studied ecosystem.

? Results

I. typographus long-distance dispersal substantially decreased with outbreak culmination. The spread of infestation was only weakly related to stand and site parameters. Infestations spread isotropically at the stand and patch level but directionally at the regional scale.

? Conclusions

The large-scale spread of infestation can be explained by the uniform age and species composition of the investigated forests and by the ability of populations to overwhelm suboptimal trees. The observations presented here suggest that secondary spruce forests in Europe may be unsustainable due to unprecedented bark beetle outbreaks, which can be further amplified by changing climate.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Spatiotemporal Availability of Dead Wood in Protected Old-growth Forests: A Case Study from Boreal Forests in Eastern Finland

Spatiotemporal patterns of standing and fallen dead trees were examined in two protected Scots pine ( Pinus sylvestris L.)-Norway spruce ( Picea abies (L.) Karst.) forests in eastern Finland (Pahkavaara and Pönttövaara). In Pahkavaara the volume of standing dead trees was 10 m 3 ha -1 and the volume of fallen logs was 66 m 3 ha -1 , and in Pönttövaara the values were 48 m 3 ha -1 and 107 m 3 ha -1 , respectively. The areas differed with respect to the tree species composition, whereas the proportion of different decay stages was similar. Decay stage and dendrochronological analyses revealed the continuity of dead wood formation. The spatial pattern of standing dead trees was usually towards clustered. The volumes of fallen logs showed a spatial autocorrelation up to distances of 10-20 m. The results also suggest that the current amount and diversity of dead wood is rather high, but that forest succession is likely to lead to a less diverse state in the future.     

Insect natural enemies of <Emphasis Type="Italic">Ips typographus</Emphasis> (L.) (Coleoptera,Scolytinae) in managed and unmanaged stands of mixed lowland forest in Poland

We tested the effects of forest management type (managed vs. unmanaged) on the abundances of Ips typographus (L.) (Col., Curculionidae, Scolytinae) and related parasitoids and predators reared from spruce bolts exposed in Białowieża, Poland. Habitat availability for these species differed between forest types mainly as a result of regular sanitary fellings occurring in managed forests. Populations of the common polyphagous insect predators Paromalus paralellepipedus (Herbst) and Plegaderus vulneratus (Panz.) (Col., Histeridae) or parasitoids Rhopalicus tutela (Walk.), Dinotiscus eupterus (Walk.) and Roptrocerus xylophagorum Ratz. (Hym., Pteromalidae) related to I. typographus did not differ between managed and unmanaged forests. Only Thanasimus spp. (Col., Cleridae) was significantly more abundant in managed forest, possibly because it was favored by the more open, sunny stands. However, the experiment was performed in stands where spruce is only a minor component and during the non-epidemic phase of the bark beetle population, so further experiments may be necessary to determine if the effects of sanitary fellings are greater in different forest types and at different stages of the population cycle.     

Estimating risks for spruce bark beetle (Ips typographus (L.)) damage using pheromone‐baited traps and trees

The risk for damage associated with spruce bark beetle attacks on living trees was estimated in 12 forest districts in the Nordic countries during three years. Pheromone‐baited traps and trees were used. Five groups of three traps were deployed annually on fresh spruce clear‐fellings in each district. The mean catches within districts and years ranged from 950 to 46000 beetles per trap group. The standard error averaged 15 % of the mean catch. One tree was baited annually at each of five other sites in each district. The mean number of trees colonized by Ips typographus in each district and year ranged from 0 to 5 per site. The standard error was high, averaging 44% of the mean. Inventories of tree mortality within the districts yielded values ranging from 0 to 150 killed trees per km of spruce forest edge. There was a strong linear correlation between mean catches in traps and log‐transformed tree mortality (r=0.82). The correlation between colonization success at tree‐baiting sites and tree mortality was weaker (r=0.59), owing to one deviant observation. The results indicate that pheromone traps and baited trees may be used to assess the risk for damage caused by Ips typographus.     

Hosts and distribution of the intersterility groups of Heterobasidion annosum in the highlands of Greece

The intersterility groups of 127 pure cultures of H, annosum collected from different host trees in 12 mountain areas in Greece were identified. The F group commonly caused butt rot on the fir species Abies cephalonica and Abies borisii regis. It was the only type of H. annosum found in pure fir forests. The P group caused serious root rot in pinus sylvestris stands in north-eastern Greece. In more southern mountain areas it often colonized stumps of pinus nigra but seldom killed this tree species. The S group was found in natural forests of Picea abies in northern Greece, causing butt rot of spruce. In mixed forests, the intersterility groups of H. annosum were found relatively often in stumps of tree species other than their main hosts, although some host preference seemed to occur also in stump colonization.     

Windthrow after Shelterwood cutting in Picea abies Peatland forests

The aim of the study was to address the question of whether shelterwood cutting should be discouraged as a forest regeneration method in Norway spruce (Picea abies (L.) Karst.) forests on highly productive peatlands due to a higher risk of windthrow in such forests. The total extent of windthrow was observed during six years after shelterwood cutting in nine spruce forests on fertile peatlands in north, central and south Sweden. Shelterwoods at densities of 140 and 200 stems ha^‐1 were studied. At the end of the six year study period, 43% of all trees in the sparser shelterwoods and 38% of the trees in the denser shelterwoods had blown down. With respect to results from recent studies of the development of naturally regenerated and planted seedlings under the shelter trees, the extent of windthrow was regarded acceptable. Analysis of wind data from national weather stations close to the experiments showed that the acceptable extent of windthrow could not be explained by low frequencies of high winds during the shelterwood period. On the contrary, according to the wind observations made at the weather stations selected in central and south Sweden, the annual number of days with high winds (>21 ms^‐1) during the six years after the shelter‐wood cutting was larger than the average high wind frequency for the last 40 years. Observations of maximum wind speeds show that the mean annual gale force during the shelterwood period was higher than the long term average. Thus, the results from this study do not justify avoidance of shelterwood cutting in spruce peatland forests because of the risk of windthrow. Each of the shelterwoods in the experiment was located close to a large clearcut, and the shelterwood cuttings were carried out as heavy thinnings. For further reduction of windthrow, denser shelterwoods and no clearcutting in adjacent stands are suggested when using shelterwood systems in practical forestry.     

Retention patches maintain diversity of epiphytic and epixylic indicator lichens more effectively than solitary trees

The effectiveness of retention trees and patches in preserving diversity of nine epiphytic and epixylic old-growth forest lichens was studied in north boreal spruce forests in Finland. We compared (1) 7–8-year-old retention cuts, with at least 5–10 living or dead retention trees per hectare, (2) 10–12-year-old clear-cuts, with some scattered living and dead retention trees on the sites, (3) old-growth spruce forests, and (4) 7-8-year-old retention patches (0.06–0.45?ha) representing the original tree species composition of old-growth forests. The occurrence of indicator lichens was studied on 150 deciduous trees and snags in each forest category. The species richness was significantly higher in old-growth forests than in the clear-cuts and retention cuts, but did not differ between old-growth forests and retention patches. Only three species were found in clear-cuts and two in retention cuts. Foliose cyanolichens Leptogium saturninum and Nephroma bellum thrived on solitary retention trees, whereas humidity-requiring pin lichens from the genus Chaenotheca were found only in old-growth forests and retention patches. Our results suggest that the ability of epiphytic and epixylic species to survive on retained trees depends on several factors: (1) substrate quality (tree species, tree type and diameter of a tree), (2) environmental factors (e.g. humidity, slope exposition), and (3) morphological and physiological characteristics of species. Besides of substrate trees, the retained conifers (esp. spruce) seem to be important in retention patches to provide the shading necessary to maintain humidity.     

Risk of Snow Damage in Unmanaged and Managed Stands of Scots Pine,Norway Spruce and Birch

The aim of this study was to assess the risk of snow damage to trees in unmanaged and managed stands of Scots pine (Pinus sylvestris L.), Norway spruce [Picea abies (L.) Karst.] and birch (Betula spp.) over a rotation. The risk assessment was based on the prediction of critical snow loads in interaction with the windspeed at which trees can be expected to break or be uprooted, and on the frequency of long-term extremes of precipitation and of suitable temperature conditions for the accumulation of snow on the tree crowns. The Scots pine stands were found to be more susceptible to snow damage than the others, and an unmanaged stand of Scots pine to be more susceptible to break and uproot than a managed one. Correspondingly, an unmanaged stand of Norway spruce was more susceptible to stem breakage than a managed one, but less susceptible to uprooting. Neither unmanaged nor managed birch stands were likely to suffer any kind of snow damage. The susceptibility of unmanaged stands is caused by low tapering of the trees. Based on the frequency of long-term extremes in precipitation at the temperatures needed for snow accumulation on tree crowns, critical snow loads of 10-19, 20-29 and 30-39 kg m^-2 occurred 19.3, 3.3 and 1.3 times in a decade in southern Finland. Critical snow loads of 10-19, 20-29, 30-39 and 60-69 kg m^-2 occurred in northern Finland 17.0, 6.3, 1.7 and 0.3 times in a decade.     

Types of bark beetle (Coleoptera: Scolytidae) infestation in spruce forest stands affected by air pollution, bark beetle outbreak and honey fungus (Armillaria mellea)

583 spruce stands in an area affected by air pollution and bark beetle outbreak in Eastern Slovakia were studied in 1996. According to bark beetle infestation of dominant and codominant trees, stands were classified into following types of spruce stand decline:Ips typographus-A,Ips typographus-B,Polygraphus poligraphus, I. typographus/P. poligraphus—A,I. typographus/P. poligraphus—B. The presence of attacked trees in forest edges, bark beetle spots and forest interior was the key important factor for the classification. Data from forest inventory and forest management evidence together with data on types of spruce stands decline were used in further analyses. Results shows that the distribution of forest stands classified into different types or uninfested stands is related mainly to host size and site quality. The percentage of spruce, exposition of stands and stand density showed significant effects. The mechanisms of spreading of studied bark beetle outbreak could be explained by direct effects of stress of trees caused by an abrupt increase of level of solar irradiation and by weakening of trees by the honey fungus.     

A review： chemical ecology of Ips typographus （Coleoptera, Scolytidae）

Chemical ecology of the spruce bark beetle lps typographus （L.） was reviewed. The outbreak of 1.typographus in central Europe triggered extensive research on chemical ecology, Males initiate host location and produce semiochemicals which attract both males and females, A successful mass attack must first overcome the resistance of the host tree. Pioneer I. typographus evolved to use the resin flow of host trees as kairomones in host location, and synthesized semiochemicals initially to detoxify the resin. If small bark beetle populations infest healthy trees, mass attack is prevented by host resistance, Nine monoterpene alcohols were found in male hind-guts, including cis-verbenol （cV） and 2-methyl-3-buten-2-ol （MB） which are regarded as primary aggregation pheromones, and a low proportion of lpsdienol （ld） which increases attractiveness of cV and MB, Verbenone （Vn） and Ipsenol （le） are anti-aggregation pheromones, that play important roles in adjusting attack density and insect density under the bark. Non-host volatiles are repellent to L typographus, so that beetles do not waste energy boring into non-host trees. The relationship between host resistance, pheromone compounds and behavior, non-host volatiles, bioassays and mass trapping are reviewed, Results of field bioassays stressed that traps baited with specific pheromones could be used as a reasonable protection measure.     

Post-windthrow management in protection forests of the Swiss Alps

The two storms Vivian (1990) and Lothar (1999) left an area of roughly 9000 ha of fully damaged protection forests in Swiss mountain regions. Given this huge dimension, questions arose on how to manage these areas to keep the protection gap, i.e. the time period with reduced overall protection against natural hazards, short. Quantifications are presented for the stability of lying logs left in place, the frequency of post-disturbance mass movements, and the tree regeneration in windthrow areas. The average height above ground of unsalvaged lying logs decreased from 2.1 m shortly after disturbance to 0.8 m 20 years later. In the period 1990–2014, the number of avalanches in windthrow areas was markedly small, and annual rates of shallow landslides and debris flows in windthrow areas did not differ from rates in comparable undamaged forested areas. Regeneration density rarely exceeded 4000 stems ha^?1 20 years post-windthrow at elevations above 1200–1500 m a.s.l. Mean height of tallest trees reached 5.6 m in areas that were cleared and 6.5 m in those left unsalvaged. Trees planted post-windthrow were 1.0–2.4 m taller than naturally regenerated ones. Practitioners rated the protective effect to be acceptable 24 years post-disturbance in only 5 out from 16 observed windthrow areas (31%), with planting trees as the main cause of success. We conclude that in protection forests the regeneration speed after disturbance rarely meets practitioner’s expectations in terms of both stem density and stand structure. However, leaving woody debris from wind disturbance in place proved to replace protective effects for an astonishingly long time. An intensive management with salvage logging, planting and even technical constructions seems therefore only inevitable on windthrown areas where risks seem too high based on hazard, damage potential and possible spread of bark beetles to nearby protection forests. A management alternative applicable to many other cases of windthrown protection forests is to plant trees between lying stems.     

Some reactions of<Emphasis Type="Italic"> Ips typographus</Emphasis> (L.) (Col.: Scolytidae) to changing breeding conditions in a forest decline area in the Sudeten Mountains,Poland

Investigations on I. typographus populations were conducted in 1992–1994 in the Sudeten (south-western Poland), in Norway spruce stands that were devastated previously by insect outbreaks and that exhibited severe forest decline. Crown defoliation and the volume of infested trees per hectare were used as indices of stand health and breeding conditions; variability in the infestation density, gallery length, and body length of beetles were parameters that were used to estimate the response of I. typographus populations to changing stand conditions. In stands located in the zone above 800 m a.s.l. where both the level defoliation and tree mortality were higher, the infestation density and body length of I. typographus were higher than in the zone below 800 m a.s.l., where stands were less damaged. Contrarily, the gallery length was higher in lower montane zone, where lower infestation densities and body length values were found. A proposed mechanism for this interaction, which is attributed mainly to better breeding conditions for I. typographus populations in weakened stands, is presented and discussed.     

Regeneration in windthrow areas in hemiboreal forests: the influence of microsite on the height growths of different tree species

Natural regeneration of windthrow areas is an important issue when planning forestry measures after forest disturbances. Seedling recruitment was investigated in storm-damaged hemiboreal mixed forests in eastern Estonia. The establishment and growth of seedlings from natural regeneration was registered for tree species in soil pits and in mounds of uprooted trees in stands that were either heavily or moderately damaged. Seedling growth is expected to be better in large but shallow soil pits created by uprooted Norway spruce [Picea abies (L.) Karst.] and poorer in small but deep pits created by the hardwoods in the area, silver birch (Betula pendula Roth.) and European aspen (Populus tremula L.). The most abundant regenerating species was birch. Pits hosted larger seedling numbers than mounds, due to soil instability in mounds. Rowan (Sorbus aucuparia L.) showed significantly faster growth than the other seedling species. Norway spruce pits were preferred to pits of other species by both birch and spruce seedlings. Black alder [Alnus glutinosa (L.) J. Gaertn.] did not show a preference for pits of a certain species of uprooted tree. Both spruce and rowan preferred hardwood mounds over spruce mounds. Storm severity also affected species composition: birch predominantly occurred on pits and mounds in heavily disturbed areas, while spruce was more abundant in the moderately damaged areas. The effects of advance regeneration and surrounding stands on seedling microsite preferences should be considered in future research and subsequent management recommendations.     

The spreading of the S type of Heterobasidion annosum from Norway spruce stumps to the subsequent tree stand

The occurrence of Heterobasidion annosum in stumps and growing trees was investigated on 15 forest sites in southern Finland where the previous tree stand had been Norway spruce (Picea abies) infected by H. annosum, and the present stand was either Scots pine (Pinus sylvestris), lodgepole pine (Pinus contorta), Siberian larch (Larix siberica), silver birch (Betula pendula) or Norway spruce 8–53 years old. Out of 712 spruce stumps investigated of the previous tree stand, 26.3% were infected by the S group and 0.3% by the P group of H. annosum. The fungus was alive and the fruit bodies were active even in stumps cut 46 years ago. In the subsequent stand, the proportion of trees with root rot increased in spruce stands and decreased in stands of other tree species. On average, one S type genet spreading from an old spruce stump had infected 3.0 trees in the following spruce stand, 0.5 trees in lodgepole pine, 0.3 trees in Siberian larch, 0.05 trees in Scots pine and 0.03 trees in silver birch stand. Although silver birch generally was highly resistant to the S type of H. annosum, infected trees were found on one site that was planted with birch of a very northern provenance.     

Availability of standing trees for large cavity-nesting birds in the eastern boreal forest of Québec,Canada

Large cavity-nesting birds depend on large-diameter trees for suitable nest sites. The increased spatial extent of commercial timber harvesting is modifying forest structure across the land base and may thus compromise the availability of large trees at the landscape scale. In this study, our objectives were to (1) characterize the availability of large living and dead trees in old-growth stands dominated by different tree species and surficial deposits that encompass the range of natural cover types of eastern Québec's boreal forest; (2) analyze the distribution of trees among decay-classes; and (3) compare the availability of large trees in unharvested, remnant, and harvested stands for the entire range of decay-classes. A total of 116 line transects were distributed across unharvested forests, remnant linear forests, and cutblocks in cutover areas. Unharvested forest stands (black spruce [Picea mariana], balsam fir [Abies balsamea]–black spruce, balsam fir–white spruce [Picea glauca] and balsam fir) reflected a gradient of balsam fir dominance. The remnant forests selected were isolated for 5–15 years. Analyses were performed at two diameter cut-off values. Trees with DBH ≥20 cm were considered for availability of total trees whereas trees with DBH ≥30 cm were considered for availability of large trees. Forest stands comprised high proportions of standing dead trees (33% of all stems, 8% were large dead stems). Availability of total and large standing trees increased with the dominance of balsam fir in stands. Forest stands located on thick surficial deposits showed higher densities of large dead trees for every stand type suggesting a higher productivity on those sites. Availability of stems according to decay-classes showed a dome-shaped distribution with higher densities of snags in intermediate decay stages. However, for large stems, black spruce stands showed a significantly lower availability that was consistent across all decay-classes. In linear remnant forests, pure balsam fir stands were absent. Remnant stands thus showed a much lower availability in large trees when compared with unharvested balsam fir stands. Clearcuts had the lowest densities of dead trees across sampled stands. Current even-aged management practices clearly affect availability and recruitment of large trees, therefore forest-dwelling wildlife relying on these structures for breeding is likely to be affected by large-scale harvesting in coniferous boreal forests.     

Fungi isolated from Picea abies infested by the bark beetle Ips typographus in the Białowieża forest in north‐eastern Poland

The assemblage of fungi occurring in the sapwood of Norway spruce (Picea abies) and in bark beetle galleries following attack by the Eurasian spruce bark beetle Ips typographus was investigated in the Bia?owie?a forest in north‐eastern Poland. Fungi were isolated from blue‐stained sapwood of beetle‐infested spruce trees in June 2002, and a few isolates were also obtained from ascospores and conidia taken from perithecia and asexual structures occurring in the gallery systems of the insects. The mycobiota of I. typographus in the Bia?owie?a forest was dominated by ophiostomatoid fungi, which were represented by seven species. Four species, including Ceratocystis polonica, Grosmannia penicillata, Ophiostoma ainoae and Ophiostoma bicolor were isolated at high frequencies, whereas three other taxa, Ceratocystiopsis minuta, Ceratocystiopsis alba and a Pesotum sp. were rare. The anamorphic fungus Graphium fimbriisporum and yeasts also occurred occasionally. In addition, the basidiomycete Gloeocystidium ipidophilum was relatively common. The pathogenic blue‐stain fungus C. polonica was the dominant fungal associate of I. typographus in the Bia?owie?a forest, which is consistent with a previous study at this area in the 1930s. Ceratocystis polonica was the most frequently isolated species at the leading edge of fungal colonization in the sapwood and had on an average penetrated deeper into the wood than other fungal associates. This suggests that it acts as a primary invader into the sapwood after attack by I. typographus in the Bia?owie?a forest, followed by O. bicolor, O. ainoae, G. ipidophilum and G. penicillata. Thus far, the Bia?owie?a forest is one of the few areas in Europe, where C. polonica has been reported as a dominate fungal associate of I. typographus.