No abstract

2004. Interspecific synchrony among foliage-feeding forest Lepidoptera species and the potential role of generalist predators as synchronizing agents. Á/ Oikos 107: 462 Á/470.While synchrony among geographically disjunct populations of the same species has received considerable recent attention, much less is known about synchrony between sympatric populations of two or more species. We analyzed time series of the abundance of ten species of spring foliage feeding Lepidoptera sampled over a 25-year period at 20 sites in the Slovak Republic. Six species were free-feeders and four were leaf-rollers as larvae. Twenty-nine percent of interspecific pairs were significantly synchronous and correlations were highest among species exhibiting similar feeding strategies. Similar patterns of interspecific synchrony have been previously demonstrated in several other taxa, and the synchronizing effects of weather and/or specialist predators have been proposed as mechanisms. As an alternative explanation, we explored a model in which two species within the same feeding guild were synchronized by the functional response of generalist predators. In this model, species remained unsynchronized in the complete absence of predation or when predatory pressures were applied to only one species. Pairs of prey species projecting relatively similar search images to predators were more highly synchronized than species with relatively different search images. Prey handling time only influenced synchrony when it was very high relative to the total time prey was exposed to predators. Our model's prediction of greater synchrony among species that project similar search images to predators was in agreement with our field study that showed greater synchrony among species sharing similar larval feeding strategies and morphologies.

We describe a series of experiments on the protection of Norway spruce (Picea abies (L.) Karst.) logs and standing trees against Ips typographus L. (Coleoptera: Scolytidae). The tested protective materials were applied 1) at point sources and 2) area-covering using zeolite-based dispensers. We performed 11 terrestrial and one aerial application (using a helicopter) between 1992 and 2001. We gradually replaced polyethylene-bag verbenone dispensers by composite dispensers releasing verbenone and non-host volatiles (NHV: green leaf volatiles, trans-conophthorin, and C8-alcohols). Many experiments did not give statistically significant results, due to the low number of true replicates and the spatial heterogeneity of beetle attacks. The protection of horizontal objects like logs or lying trees with anti-attractants was not always successful. In the future, positive results can be expected with an area covering spray applied by zeolite dispensers containing mixtures of verbenone and NHV. A similar approach could probably be used in aerial spraying of anti-attractants.We have succeeded in our attempt to protect zones of standing spruce trees from I. typographus attacks. We used dispensers with a combination of verbenone and a full blend of NHV compounds. The protection is not complete, but in both 2000 and 2001, the treatment significantly decreased the probability of the insect attack on trees by 60-80 %.

We analysed climate change impacts on the growth and natural mortality of forest tree species and forest carbon (C) balance along an elevation gradient extending from the Pannonian lowland to the West Carpathian Mountains (Central Europe). Norway spruce Picea abies, European beech Fagus sylvatica, and oak Quercus sp. were investigated for 2 future time periods: 2021-2050 and 2071-2100. The period 1961-1990 was used as reference. Forest growth simulations were based on the SIBYLA tree growth simulator (an empirical model), and C cycle-related simulations were performed using BIOME-BGC (a process-based biogeochemical model). Growth simulations indicated that climate change will substantially affect the growth of spruce and beech, but not of oak, in Central Europe. Growth of spruce and beech in their upper distribution ranges was projected to improve, while drought-induced production decline was projected at the species' receding edges. Beech was the only species projected to decline critically at lower elevations. C cycle simulations performed for the zone of ecological optima of the 3 tree species indicated that these forests are likely to remain net carbon dioxide sinks in the future, although the magnitude of their sequestration capacity will differ. Increasing nitrogen deposition and atmospheric carbon dioxide concentration were projected to greatly affect the forest C cycle. A multi-model assessment based on SIBYLA and BIOME-BGC simulations performed for the zone of ecological optima suggested that oak production will either remain the same as in the reference period or will increase. Future production of beech seems uncertain and might decline, while spruce production is likely to increase. The results also confirmed the value of multi-model approaches for assessing future forest development under climate change.KEY WORDS: Norway spruce · European beech · Oak · Forest carbon cycle · Tree production · Tree mortality · BIOME-BGC model · SIBYLA tree growth simulator Resale or republication not permitted without written consent of the publisher

• 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.