Jacek Hilszczański

Saproxylic and non-saproxylic beetle assemblages in boreal spruce forests of different age and forestry intensity.

Current clear-cutting forestry practices affect many boreal organisms negatively, and those dependent on dead wood (saproxylics) are considered as particularly vulnerable. The succession of species assemblages in managed forest habitats regenerating after clear-cutting is, however, poorly known. We compared beetle assemblages in three successional stages of managed boreal spruce forests established after clear-cutting and two types of older spruce forests that had not been clear-cut. We also assessed whether saproxylic and non-saproxylic beetle assemblages show similar biodiversity patterns among these forest types. Beetles were collected in window traps in nine study areas, each encompassing a protected old-growth forest (mean forest age approximately 160 years, mean dead wood volume 34 m3/ha), an unprotected mature forest (approximately 120 years old, 15 m3/ha), a middle-aged commercially thinned forest (53 years old, 3 m3/ha), a young unthinned forest (30 years old, 4 m3/ha), and a clearcut (5-7 years after harvest, 11 m3/ha). Saproxylic beetles, in particular red-listed species, were more abundant and more species rich in older forest types, whereas no significant differences among forest types in these variables were detected for non-saproxylics. The saproxylic assemblages were clearly differentiated; with increasing forest age, assemblage compositions gradually became more similar to those of protected old-growth forests, but the assemblage composition in thinned forests could not be statistically distinguished from those of the two oldest forest types. Many saproxylic beetles adapted to late-successional stages were present in thinned middle-aged forests but absent from younger unthinned forests. In contrast, non-saproxylics were generally more evenly distributed among the five forest types, and the assemblages were mainly differentiated between clearcuts and forested habitats. The saproxylic beetle assemblages of unprotected mature forests were very similar to those of protected old-growth forests. This indicates a relatively high conservation value of mature boreal forests currently subjected to clear-cutting and raises the question of whether future mature forests will have the same qualities. Our results suggest a high beetle conservation potential of developing managed forests, provided that sufficient amounts and qualities of dead wood are made available (e.g., during thinning operations). Confirming studies of beetle reproduction in dead wood introduced during thinning are, however, lacking.

Micro and Macro-Habitat Associations in Saproxylic Beetles: Implications for Biodiversity Management

Restoration of habitats is critically important in preventing full realization of the extinction debt owed as a result of anthropogenic habitat destruction. Although much emphasis has been placed on macrohabitats, suitable microhabitats are also vital for the survival of most species. The aim of this large-scale field experiment was to evaluate the relative importance of manipulated microhabitats, i.e., dead wood substrates of spruce (snags, and logs that were burned, inoculated with wood fungi or shaded) and macrohabitats, i.e., stand types (clear-cuts, mature managed forests, and forest reserves) for species richness, abundance and assemblage composition of all saproxylic and red-listed saproxylic beetles. Beetles were collected in emergence traps in 30 forest stands in 2001, 2003, 2004 and 2006. More individuals emerged from snags and untreated logs than from burned and shaded logs, but species richness did not differ among substrates. Assemblage composition differed among substrates for both all saproxylics and red-listed saproxylic species, mainly attributed to different assemblage composition on snags. This suggests that the practise of leaving snags for conservation purposes should be complemented with log supplementation. Clear-cuts supported fewer species and different assemblages from mature managed forests and reserves. Neither abundance, nor species richness or assemblage composition differed between reserves and mature managed forests. This suggests that managed stands subjected to selective cutting, not clear-felling, maintain sufficient old growth characteristics and continuity to maintain more or less intact assemblages of saproxylic beetles. Thus, alternative management methods, e.g., continuity forestry should be considered for some of these stands to maintain continuity and conservation values. Furthermore, the significantly higher estimated abundance per ha of red-listed beetles in reserves underlines the importance of reserves for maintaining viable populations of rare red-listed species and as source areas for saproxylic species in boreal forest landscapes.

The oak buprestid beetle,Agrilus biguttatus (F.) (Col., buprestidae), a recent factor in oak decline in Europe

During last years, the populations of the oak buprestid beetleAgrilus biguttatus (Fab.) in Europe have increased. In several countries, the beetles’ attacks have become a new component in oak dieback. The larvae excavate galleries under the bark of weakened trees, which are killed through the girdling. Because of the difficult diagnosis it is necessary to draw more attention to the infestations. Therefore, this paper presents a review on the literature concerning the recognition of the infestations by the insect and its bionomics.

Insect natural enemies of Ips typographus (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.

Management Strategies for Bark Beetles in Conifer Forests

Several species of bark beetles (Coleoptera: Curculionidae, Scolytinae) are capable of causing significant amounts of tree mortality in conifer forests throughout much of the world. In most cases, these events are part of the ecology of conifer forests and positively influence many ecological processes, but the economic and social implications can be significant. Several tactics are available to manage bark beetle infestations and to reduce associated levels of tree mortality. Direct control involves short-term tactics designed to address current infestations by manipulating beetle populations, and typically includes the use of fire, insecticides, semiochemicals, sanitation harvests, or a combination of these treatments. Indirect control is preventive and designed to reduce the probability and severity of future infestations within treated areas by manipulating stand, forest and/or landscape conditions by reducing the number of susceptible hosts through thinning, prescribed burning, and/or altering age classes and species composition. The purpose of this chapter is to synthesize information related to the management of bark beetles in conifer forests.

The effect of temperature and humidity changes on insects development their impact on forest ecosystems in the expected climate change

Abstract Ongoing climate change is mainly evident as increased in average temperature. It is expected to have a significant impact on world’s biomes, with forest ecosystems especially vulnerable to these changes. The effect of climate change on forests is both indirect, through its impact on various tree species of different ecological requirements, and direct, through its impact on all living components of the forest ecosystem. Among the latter, insects are the group of the greatest importance, including species detrimental to forest health. The impact of climate change on forest insects may be reflected in their distribution, phenology, activity, number of generations and, indirectly, through impact on their natural enemies. Predicting the future direction and pace of the climate change, as well as direct and indirect consequences of its effect on forest insects is difficult and often subject to considerable inaccuracy. The paper presents a review of data from the published literature in this area of study. The influence of the basic climate parameters, temperature and humidity, on forest herbivore insects is discussed, particularly in the context of the most probable scenarios of climate change, i.e. the gradual increase in the average temperature. Observed and projected impacts of climate change in relation to the influence of herbivorous insects on forest ecosystems are characterized. We present some of the possible adaptation strategies of forest management to the expected climate changes.

Surrogate tree cavities: boxes with artificial substrate can serve as temporary habitat for Osmoderma barnabita (Motsch.) (Coleoptera, Cetoniinae)

Abstract Many saproxylic insects have declined or became extinct, mainly due to habitat loss and fragmentation, and their survival increasingly depends on active conservation. Efforts to achieve this goal may be supported by the introduction of new methods, including creation of artificial habitats. Here we present results of studies on the use of wooden boxes mimicking tree cavities for an endangered saproxylic species, Osmoderma barnabita. Boxes were filled with the feeding substrate for larvae and installed on trees. Second and third-instar O. barnabita larvae were introduced in half of the boxes; the remaining ones were left uninhabited. Later inspection of boxes showed a high survival rate of introduced larvae, as well as successful breeding of a new generation inside the boxes. At the same time boxes were not colonized by the local population of O. barnabita, although other cetoniids did so. The co-occurring larvae of other cetoniids did not affect O. barnabita larvae. Thermal conditions inside boxes and natural tree cavities were almost identical and based on the results of our studies we conclude that wooden boxes may serve as temporary habitat for O. barnabita. They may be particularly useful in cases of destruction of species’ natural habitat, in restoration programs, and have the potential to act as a ‘stepping stones’ in cases of a lack of habitat continuity.

Tree species and position matter: the role of pests for survival of other insects

We investigated insects overwintering in Norway spruce and Scots pine killed by cambium‐feeding beetles. The study was conducted in five large forests in north‐eastern Poland. Insects were reared from wood samples cut from the upper and lower parts of trees growing in both shaded and sun‐exposed conditions. We found that the species richness of overwintering insects on killed trees was mainly driven by the position in the lower trunk strata rather than in crowns or along a sun–shade gradient. Even though pine and spruce shared almost the same species composition, spruce hosted a significantly higher number of species, including beneficial ones. These results support the hypothesis that disturbance regimes change the spatial distribution of biodiversity, which is higher in low strata, as is known for abiotic disturbances that change the environment of the forest. One of the most important messages emerging from the present study is that pest beetle disturbance during non‐outbreak periods creates habitats that are necessary for the survival of myriads of other insects. Thus, maintaining parts of the trees that were killed by bark and wood‐boring beetles, especially high stumps, would help to support biodiversity in managed forests.

Saproxylic moths reveal complex within-group and group-environment patterns

We investigated saproxylic moths of the family Tineidae, a neglected group inhabiting wood-decaying fungi and dead wood, within the Białowieża Primeval Forest in Poland. Study data were obtained from the collection of 280 fruiting bodies of wood-decaying fungi and the subsequent rearing of adults. Spatial and statistical distribution of saproxylic moths, relationship among species and the influence of environment reflected by interaction with tree and fungal species together with tree and stand level characteristics were studied. Fifteen species and 533 individuals of saproxylic moths were reared. The fungal species, number of fruiting bodies and standing position of a tree influenced species richness. Moth abundance was influenced by fungal species, coniferous trees, increasing tree diameter, number of fruiting bodies and brown rot. Moth abundance was also enhanced by standing dead trees located in managed forests with higher canopy closure. Analyses indicate that several moth species favor a particular rot type and that some fungi host a richer fauna than others. Furthermore, our results indicate mutually independent fungal colonization events by saproxylic moth species, and thus a possible mechanism exists for competition avoidance with other saproxylic moths. Saproxylic moths revealed complex within-group patterns that responded differently to environmental variables. Thus, potential conservation of these organisms requires various approaches including ecosystem management, especially in the context of addressing their diverse habitat requirements.

European species of subgenus Moerophora Foerster of Xorides Latreille (Hymenoptera: Ichneumonidae: Xoridinae), with descriptions of two new species

The European species of the subgenus Moerophora Foerster, 1869, of the genus Xorides Latreille, 1809 (= Xorides rufipes species-group, Wahl 1997) (Ichneumonidae: Xoridinae) are reviewed. A key to the species and notes on their distribution are provided. Seven species are recorded from Europe: X. (M.) austriacus (Clement), X. (M.) ephialtoides (Kriechbaumer), X. (M.) jakovlevi (Kokujev), X. (M.) rufipes (Gravenhorst), X. (M.) rusticus (Desvignes) and two new species, X. (M.) flavotibialis and X. (M.) ilignus, which are described. Macrosterotrichus bischoffi (Clement) is synonymized with Xylonomus rusticus Desvignes. Xorides (M.) rufipes is recorded as new to Croatia and Bosnia.