Jakub Horák

The species richness of click beetles in ancient pasture woodland benefits from a high level of sun exposure

Forests support high concentrations of species and beetles in particular are often used to evaluate forest biodiversity. Ancient pasture woodlands are facing a major decline in Europe mainly due to the abandonment of traditional management and subsequent succession. We studied click beetles (Coleoptera: Elateridae) in one of the largest central-European remnants of pasture woodland in Lány Game Park (Czech Republic) using flight interception traps placed at standing veteran trees. The gradient of sun-exposure, circumference of stem, height and vitality of tree and tree species were studied in relation to the species richness of click beetles and their ecological groups. Total species richness reached nearly one half of the recently documented fauna in the study area and species accumulations showed us that the majority of species were represented. Most species preferred solitary trees in sun-exposed habitats and avoided shaded trees in closed canopies. The same results were obtained for ecological groups, such as saproxylic and non-saproxylic species, functional groups and guilds. Our results showed that the species richness of one of the most ecologically diverse beetle families, click beetles, benefits from a high level of sun exposure. Thus, the long spatial and temporal continuity of sun-exposed veteran trees could be a good predictor for sustainable forest management.

Saproxylic beetle thrives on the openness in management: a case study on the ecological requirements of Cucujus cinnaberinus from Central Europe

Abstract.  1. Saproxylic beetles are a key group when assessing forest biodiversity, and biologists have been trying to explore their ecological requirements.

Effect of Site Level Environmental Variables, Spatial Autocorrelation and Sampling Intensity on Arthropod Communities in an Ancient Temperate Lowland Woodland Area

The interaction of arthropods with the environment and the management of their populations is a focus of the ecological agenda. Spatial autocorrelation and under-sampling may generate bias and, when they are ignored, it is hard to determine if results can in any way be trusted. Arthropod communities were studied during two seasons and using two methods: window and panel traps, in an area of ancient temperate lowland woodland of Zebracka (Czech Republic). The composition of arthropod communities was studied focusing on four site level variables (canopy openness, diameter in the breast height and height of tree, and water distance) and finally analysed using two approaches: with and without effects of spatial autocorrelation. I found that the proportion of variance explained by space cannot be ignored (≈20% in both years). Potential bias in analyses of the response of arthropods to site level variables without including spatial co-variables is well illustrated by redundancy analyses. Inclusion of space led to more accurate results, as water distance and tree diameter were significant, showing approximately the same ratio of explained variance and direction in both seasons. Results without spatial co-variables were much more disordered and were difficult to explain. This study showed that neglecting the effects of spatial autocorrelation could lead to wrong conclusions in site level studies and, furthermore, that inclusion of space may lead to more accurate and unambiguous outcomes. Rarefactions showed that lower sampling intensity, when appropriately designed, can produce sufficient results without exploitation of the environment.

Unexpected visitors: flightless beetles in window traps

Ancient woodlands are highly important for biodiversity. Flightless beetles and window traps may first appear to be incompatible as a study group and a study method. Little is known about the actual capability of window traps in monitoring of entire forest arthropod communities. We try to determine the possibility of using window traps (designed as tree traps) as an additional method to trap flightless beetles of the genera Carabus (Carabidae), Acalles and Trachodes (Curculionidae), as vulnerable representatives of wildlife forest fauna with high conservation value. From the environmental point of view, the occurrence of the studied flightless beetles was significantly more influenced by altitude than tree species as the studied environmental variables. Several beetles also showed positive significant species to species relationships during their observed phenological activity. Our results showed that the studied flightless beetles may reappear in secondary forests if these reach their optimal structure. On the other hand, they may be sensitive to large scale disturbances and not only to those caused by commercial forestry. The results also showed that window traps designed as tree traps could be used to successfully trap assemblages of forest fauna including flightless species.

Changing roles of propagule, climate, and land use during extralimital colonization of a rose chafer beetle

Regardless of their ecosystem functions, some insects are threatened when facing environmental changes and disturbances, while others become extremely successful. It is crucial for successful conservation to differentiate factors supporting species’ current distributions from those triggering range dynamics. Here, we studied the sudden extralimital colonization of the rose chafer beetle, Oxythyrea funesta, in the Czech Republic. Specifically, we depicted the range expansion using accumulated historical records of first known occurrences and then explained the colonization events using five transformed indices depicting changes in local propagule pressure (LPP), climate, land use, elevation, and landscape structure. The slow occupancy increase of O. funesta before 1990 changed to a phase of rapid occupancy increase after 1990, driven not only by changes in the environment (climate and land use) but also by the spatial accumulation of LPP. Climate was also found to play a significant role but only during the niche-filling stage before 1990, while land use became important during the phase of rapid expansion after 1990. Inland waters (e.g., riparian corridors) also contributed substantially to the spread in the Czech Republic. Our method of using spatially transformed variables to explain the colonization events provides a novel way of detecting factors triggering range dynamics. The results highlight the importance of LPP in driving sudden occupancy increase of extralimital species and recommend the use of LPP as an important predictor for modeling range dynamics.

Cucujus tulliae sp. n. – an endemic Mediterranean saproxylic beetle from genus Cucujus Fabricius, 1775 (Coleoptera, Cucujidae), and keys for identification of adults and larvae native to Europe

Abstract Cucujus tulliae sp. n. is described as a new member of genus Cucujus Fabricius, 1775 (Coleoptera, Cucujidae), which enumerates at present eleven species distributed in Eurasia and northern America. This saproxylic beetle is the first Cucujus species known only from Mediterranean and it is probably endemic to Calabria (Italy). The species was found especially in old–growth mountain forests of high conservation value (i.e. national parks) dominated by Calabrian pine (Pinus laricio calabrica). We hypothesize that Cucujus tulliae sp. n. probably evolved from isolated populations of Cucujus haematodes Erichson, 1845. The species is thus relictual and of high conservation value, corresponding at least to endangered (EN) category with respect to recent IUCN criterion. Cucujus tulliae sp. n. is here compared with two species native to Europe – Cucujus haematodes and Cucujus cinnaberinus (Scopoli, 1763) and with the Caucasian Cucujus haematodes caucasicus Motschulsky, 1845, which is confirmed as a valid subspecies. The male genitalia of this Caucasian form have been examined and illustrated for the first time. A comprehensive key to adults and larvae of European species is provided.

Ecological requirements of a rare saproxylic beetle Cucujus haematodes– the beetles’ stronghold on the edge of its distribution area

Abstract.  1. Cucujus haematodes is a rare obligate saproxylic beetle with Eurasian distribution range.

Can rove beetles (Staphylinidae) be excluded in studies focusing on saproxylic beetles in central European beech forests

Monitoring saproxylic beetle diversity, though challenging, can help identifying relevant conservation sites or key drivers of forest biodiversity, and assessing the impact of forestry practices on biodiversity. Unfortunately, monitoring species assemblages is costly, mainly due to the time spent on identification. Excluding families which are rich in specimens and species but are difficult to identify is a frequent procedure used in ecological entomology to reduce the identification cost. The Staphylinidae (rove beetle) family is both one of the most frequently excluded and one of the most species-rich saproxylic beetle families. Using a large-scale beetle and environmental dataset from 238 beech stands across Europe, we evaluated the effects of staphylinid exclusion on results in ecological forest studies. Simplified staphylinid-excluded assemblages were found to be relevant surrogates for whole assemblages. The species richness and composition of saproxylic beetle assemblages both with and without staphylinids responded congruently to landscape, climatic and stand gradients, even when the assemblages included a high proportion of staphylinid species. At both local and regional scales, the species richness as well as the species composition of staphylinid-included and staphylinid-excluded assemblages were highly positively correlated. Ranking of sites according to their biodiversity level, which either included or excluded Staphylinidae in species richness, also gave congruent results. From our results, species assemblages omitting staphylinids can be taken as efficient surrogates for complete assemblages in large scale biodiversity monitoring studies.

Fragmented habitats of traditional fruit orchards are important for dead wood-dependent beetles associated with open canopy deciduous woodlands

The conservation of traditional fruit orchards might be considered to be a fashion, and many people might find it difficult to accept that these artificial habitats can be significant for overall biodiversity. The main aim of this study was to identify possible roles of traditional fruit orchards for dead wood-dependent (saproxylic) beetles. The study was performed in the Central European landscape in the Czech Republic, which was historically covered by lowland sparse deciduous woodlands. Window traps were used to catch saproxylic beetles in 25 traditional fruit orchards. The species richness, as one of the best indicators of biodiversity, was positively driven by very high canopy openness and the rising proportion of deciduous woodlands in the matrix of the surrounding landscape. Due to the disappearance of natural and semi-natural habitats (i.e., sparse deciduous woodlands) of saproxylic beetles, orchards might complement the functions of suitable habitat fragments as the last biotic islands in the matrix of the cultural Central European landscape.

Tree level indicators of species composition of saproxylic beetles in old-growth mountainous spruce–beech forest through variation partitioning

Forest reserves can serve as an opportunity for studying natural processes in the wild. We studied the effect of easy-to-see tree level indicators on saproxylic beetles (Coleoptera), using window traps. Our study was conducted in old-growth mountainous spruce–beech forest Bukacka in the Orlicke Mts. (Czech Republic). Our analyses showed that the species composition of the study group and its response to tree level indicators in the relatively homogenous environment of old-growth mountainous forest area could be explained reasonably well through variance partitioning. The results indicated that the decay stage was the category hosting the highest level of explained variance with respect to saproxylics, followed by diameter and tree. Red-listed beetle species were nearly the same associated with conifers and broadleaves. Our results highlighted the desirability of using tree level indicators to assess insect diversity, using window traps on tree trunk.