Jan Šipoš

Phylogenetic composition of host plant communities drives plant-herbivore food web structure

Insects tend to feed on related hosts. The phylogenetic composition of host plant communities thus plays a prominent role in determining insect specialization, food web structure, and diversity. Previous studies showed a high preference of insect herbivores for congeneric and confamilial hosts suggesting that some levels of host plant relationships may play more prominent role that others. We aim to quantify the effects of host phylogeny on the structure of quantitative plant-herbivore food webs. Further, we identify specific patterns in three insect guilds with different life histories and discuss the role of host plant phylogeny in maintaining their diversity. We studied herbivore assemblages in three temperate forests in Japan and the Czech Republic. Sampling from a canopy crane, a cherry picker and felled trees allowed a complete census of plant-herbivore interactions within three 0·1xa0ha plots for leaf chewing larvae, miners, and gallers. We analyzed the effects of host phylogeny by comparing the observed food webs with randomized models of host selection. Larval leaf chewers exhibited high generality at all three sites, whereas gallers and miners were almost exclusively monophagous. Leaf chewer generality dropped rapidly when older host lineages (5-80xa0myr) were collated into a single lineage but only decreased slightly when the most closely related congeneric hosts were collated. This shows that leaf chewer generality has been maintained by feeding on confamilial hosts while only a few herbivores were shared between more distant plant lineages and, surprisingly, between some congeneric hosts. In contrast, miner and galler generality was maintained mainly by the terminal nodes of the host phylogeny and dropped immediately after collating congeneric hosts into single lineages. We show that not all levels of host plant phylogeny are equal in their effect on structuring plant-herbivore food webs. In the case of generalist guilds, it is the phylogeny of deeper plant lineages that drives the food web structure whereas the terminal relationships play minor roles. In contrast, the specialization and abundance of monophagous guilds are affected mainly by the terminal parts of the plant phylogeny and do not generally reflect deeper host phylogeny.

Dwarf pine: invasive plant threatens biodiversity of alpine beetles

Despite their small extent, alpine ecosystems belong to the most valuable, yet highly threatened natural biotopes worldwide. Alpine habitats are endangered particularly by anthropogenic influences and climate change as well as invasions of non-native plants. Although plant invasions are regarded as one of the most serious threats to biodiversity globally, the knowledge of their impact on the arthropod assemblages of alpine environments is virtually absent. Therefore, we studied the effects of the non-native dwarf pine Pinus mugo on a model group of carabid beetles in the alpine zone of the Hrubý Jeseník Mts., Czech Republic. We evaluated the effects of age, cover and distance from dwarf pine stands on the community structure and the functional diversity of the Carabidae. The majority of the species significantly declined in abundance with increasing age and cover of dwarf pine stands. Species surviving there were typically food generalists associated with the forest environment. In contrast, carabids with high conservation value bound to open habitats (e.g., Amara erratica and Carabus sylvestris) decreased in dwarf pine areas as well as food specialists (e.g., Cychrus caraboides) and large forest species in the genus Carabus. The decline in abundance of carnivorous species may be a consequence of the similar decline in herbivores dependent on the native vegetation. Concurring with this interpretation, abundance of many herbivorous species (e.g. Amara spp.) decreased within pine stands. The negative effect of dwarf pine stands on the community structure of montane carabids was also apparent in changes of functional diversity. Age and cover of dwarf pine significantly decreased functional richness and divergence of carabid trophic groups. Considering the small area of alpine tundra in the Central European mountain ranges, the expansive dwarf pine represents a serious threat to this unique montane biodiversity. Therefore we recommend the immediate reduction or removal of non-native dwarf pine stands.

Effect of canopy openness on the pressure of predatory arthropods and birds on epigeic insects

As canopy structure produces spatial heterogeneity of litter microclimatic conditions and thus is a crucial factor affecting ground insects, we hypothesized that low canopy openness has a positive effect on the activity of ground insect predators in forest and non-forest habitats. Blowfly larvae were used as bait along the canopy openness gradient (forest interior, forest edge, base of a solitary tree and meadow) and the attack rate was assessed after 30 min of exposure. Although the predation rate has a varying pattern throughout the year in different habitats, in contrast to previous studies, we observed a significant positive trend in predation rates toward the forest interior. A significant trend in predation rate was not observed in non-forest areas. We found that the trend was strongly influenced by ants as the most active taxon of predators (65%) attacking our baits, whereas ground beetles, the second-most active predators (21%), showed the opposite trend along the canopy openness gradient.

Enigmatic adult overwintering in damselflies: coexistence as weaker intraguild competitors due to niche separation in time

Odonata, like most freshwater invertebrates, tend to overwinter in water due to the thermal properties of a water environment. Winter damselflies (genus Sympecma), however, hibernate as adults in terrestrial habitats. The strategy of adult overwintering combined with high mortality is associated with several unique adaptations to semiarid conditions, but winter damselflies maintain this unique life history throughout almost the entire Palaearctic. We assume that the unique strategy of adult overwintering in temperate zones is indirectly maintained by niche separation in time. We used phenological data from the Czech Republic to compare the seasonal phenology of Sympecma spp. with other coexisting odonate species. Seasonal population growth patterns between S. fusca and other coexisting species representing different life histories were compared using GLMMs and LME. The models showed negative non-linear dependence between the population growth of S. fusca and the estimated abundance of compared species. We found that the specific strategy of adult overwintering makes it possible to avoid seasonal maxima of competition and predation in adult and larval stages. Adults may benefit from free niches during spring while larvae may benefit from size advantage among intraguild competitors and optimal conditions for development.

Assessment of trends in predation pressure on insects across temperate forest microhabitats

Experimental tests of whether predation pressure on insects is sometimes restricted to particular forest microhabitats have been carried out only in one or two vegetation periods and described for only a few predators. In the present study, we describe the seasonal dynamics of a wide spectrum of insect predators among forest microhabitats. We also examine the impact of weather conditions on insect predation, and predict that forest openness would influence the predation trends among forest microhabitats. The design of our experiments enabled direct measurement of relative predation pressure on bait (larvae of the blowfly Calliphora vicina) pinned onto selected microhabitats (the base, trunk and leaves of trees) within a temperate floodplain forest (Czech Republic). The most parsimonious generalized additive model showed significant trends in the predation rate among the forest microhabitats. The highest predation rate for bait was at the base of trees and the lowest predation rate was on leaves. We also observed significant differences in the species structure of predators in various microhabitats. The most common source of predation on trunks was from birds, whereas wasps were the most common predator on leaves and ants were the most common at the base of trees.

Trends and events through seven centuries: the history of a wetland landscape in the Czech Republic

Environmental change can be viewed as the combined result of long-term processes and singular events. While long-term trends appear to be readily available for observation (in the form of temporal comparisons or space-for-time substitution), it is more difficult to gain information on singular events in the past, although these can be equally significant in shaping ecosystems. We examined the past 700xa0years in the history of a lowland wetland landscape in the Czech Republic with the help of palaeoecological, ecological, landscape archaeological, and archival data. Macrofossil and pollen data were compared to known drainage works in the area and historical climatological data. Trends and events in habitat conditions were assessed using species indicator values. Results showed that ecological succession was the general process in the study area, detected as a trend towards eutrophication, desiccation, and vegetation closure. Short-term events influenced development at the sites mainly from the second half of the nineteenth century. This is consistent with drainage history, although bias related to sample frequency cannot be excluded. On the whole, long-term trends and discrete events were complementary on different scales. We conclude that humans facilitated and accelerated background processes, which can be most likely associated with the succession of open wetlands towards terrestrial ecosystems.

Dynamics of herbaceous vegetation during four years of experimental coppice introduction

Understanding the effects of coppicing on forest ecosystems is important for progress towards sustainable forest management. A newly established coppicing experiment in a secondary temperate deciduous forest in the SE Czech Republic provides a rather unique insight into succession driven by canopy thinning in a forest still lacking species typical for forests established a long time ago. Herbaceous layer vegetation was monitored for four subsequent years in 2012–2015. We focused on the influence of canopy thinning intensity in two different forest types defined by dominant tree species (oak and lime). Our results showed that the opening of the canopy had immediate effects on herbaceous vegetation. Coverage, species richness and compositional patterns followed the coppicing intensity gradient. The dominant tree species had contrasting effects. Under oak, the reaction to coppicing was weak. Under lime, strong reaction both related to coppicing intensity and temporal development was observed. Herbs with short life cycle had the greatest contribution, but perennial grasses also began to increase their coverage after coppicing. Several invasive species, mostly short-lived herbs, emerged but are supposed to retreat as the succession will proceed. We conclude that coppice introduction into a secondary forest led to contrasting patterns related to dominant tree species. The marked difference was probably due to the slow succession towards a future forest community saturated by species. This process may now be further diversified by coppicing management.

Vertical distribution of earwigs (Dermaptera: Forficulidae) in a temperate lowland forest, based on sampling with a mobile aerial lift platform

Although earwigs (Dermaptera) may be important components of ecosystems because of their locally high abundance and omnivory, their vertical distribution among forest strata is poorly understood. This study used a mobile aerial lift platform to survey the spatiotemporal distribution of earwigs along the vertical dimension in a forest. In 2013 and 2014, 57 trees in a lowland floodplain forest were sampled in the southeastern Czech Republic, Central Europe. Earwigs were collected along the complete vertical gradient of the foliage of the trees using square beating sheets and exhaustors. Of the three recorded earwig species (Apterygida media, Chelidura acanthopygia and Forficula auricularia), A.u2009media was the most abundant. The distribution of its abundance with the height from ground (in the tree leaf layer) was unimodal, with a peak at 4–10u2009m, indicating that A.u2009media is arboricolous. The vertical stratification of A.u2009media differed among developmental stages, and in its abundance among tree species. Investigation of insect vertical stratification in forests should be facilitated by the use of a mobile aerial lift platform.

Patterns of functional diversity of two trophic groups after canopy thinning in an abandoned coppice

Coppice abandonment had negative consequences for the biodiversity of forest vegetation and several groups of invertebrates. Most coppicing restoration studies have focused only on a single trophic level despite the fact that ecosystems are characterized by interactions between trophic levels represented by various groups of organisms. To address the patterns of functional diversity in the perspective of coppicing restoration, we studied the short-term effects of conservation-motivated tree canopy thinning in an abandoned coppice with standards in Central Europe, a region where such attempts have been rare so far. The functional diversity of vascular plants and spiders, chosen as two model trophic groups within the forest ecosystem, was compared between thinned and control forest patches. To characterize functional patterns, we examined several functional traits. These traits were assigned to two contrasting categories: response traits reflecting a change of environment (for both vascular plants and spiders) and effect traits influencing the ecosystem properties (only for vascular plants). Functional diversity was analysed by CCA using two measures: community-weighted means (CWM) and Rao’s quadratic diversity (RaoQ). CCA models revealed that the canopy thinning had a positive effect on the diversity of the response traits of both trophic groups and negatively influenced the diversity of effect traits. In addition, we found distinct seasonal dynamics in functional diversity of the spider communities, which was probably linked to leaf phenology of deciduous trees. We conclude that canopy thinning affected functional diversity across trophic groups during the initial phase of coppicing restoration. With necessary precautions, careful canopy thinning can be effectively applied in the restoration of functional diversity in abandoned coppices.

Consequences for selected high-elevation butterflies and moths from the spread of Pinus mugo into the alpine zone in the High Sudetes Mountains

Due to changes in the global climate, isolated alpine sites have become one of the most vulnerable habitats worldwide. The indigenous fauna in these habitats is threatened by an invasive species, dwarf pine (Pinus mugo), which is highly competitive and could be important in determining the composition of the invertebrate community. In this study, the association of species richness and abundance of butterflies with the extent of Pinus mugo cover at individual alpine sites was determined. Butterflies at alpine sites in the High Sudetes Mountains (Mts.) were sampled using Moericke yellow water traps. The results of a Canonical Correspondence Analysis (CCA) indicated that at a local scale the area of alpine habitats is the main limiting factor for native species of alpine butterflies. Butterfly assemblages are associated with distance to the tree-line with the optimum situated in the lower forest zone. In addition the CCA revealed that biotic factors (i.e. Pinus mugo and alpine tundra vegetation) accounted for a significant amount of the variability in species data. Regionally, the CCA identified that the species composition of butterflies and moths is associated with presence and origin of Pinus mugo. Our study provides evidence that the structure of the Lepidopteran fauna that formed during the postglacial period and also the present composition of species assemblages is associated with the presence of Pinus mugo. With global warming, Pinus mugo has the potential to spread further into alpine areas and negatively affect the local species communities.