A monograph on the morphology and life and distribution traits of Prostomis west palearctic is proposed. Five species are recognized, one of which from southern Greece is unpublished and described: ...Prostomis hellenica n. sp. Two Eastern European species, whose types have not been consulted (P. grandis Fursov, 1935 and P. brunneus Fursov, 1935), are probably synonyms respectively of P. elburica Fleischer, 1919 and P. mandibularis (Fabricius, 1801). The morpho-specific diagnostic characters of five species are macro-photographed and an illustrated key is proposed to recognize them and guide possible new discoveries still possible in the west Palearctic.
Une monographie sur la morphologie, les traits de vie et la répartition des Prostomis ouest-paléarctiques est proposée. Cinq espèces sont reconnues, dont une du sud de la Grèce est inédite et décrite: Prostomis hellenica n. sp. Deux espèces d’Europe orientale, dont les types n’ont pas été consultés (P. grandis Fursov, 1935 et P. brunneus Fursov,1935), sont probablement des synonymes respectivement de P. elburica Fleischer, 1919 et P. mandibularis (Fabricius, 1801). Les caractères morpho-spécifiques diagnostiques des cinq espèces sont présentés et une clé dichotomique illustrée est proposée pour les reconnaitre et guider d’éventuelles nouvelles découvertes encore possibles dans l’ouest paléarctique.
▶ The contribution of each stratum to saproxylic biodiversity depends on dominant tree species. ▶ Canopy and ground strata harbor beetle specialist taxa in temperate forest. ▶ Canopy species ...assemblages are not nested subsets of species-richer ground assemblages. ▶ Forest management practices in favour of canopy micro-habitats have to be promoted.
Conserving saproxylic beetles in temperate forests will require a better understanding of habitat requirements. So far, quantitative community studies have rarely considered their vertical requirements. In comparison with the tropical forest canopy, it remains to be seen whether a comparably high level of beetle diversity exists in the temperate forest canopy.
We compared saproxylic beetle assemblages at two vertical levels in three temperate French forests. Two datasets originated from emergence traps of pine and oak deadwood substrates (mid-canopy and forest floor branches) in lowland forests. The third compared flying beetle fauna at mid-canopy and understory levels using pairs of flight interception traps in beech-fir mountain forests.
Our study provided contrasting results regarding the contribution of each stratum to biodiversity. Whereas higher abundance and species richness were apparent in understory samples in beech-fir stands and in oak branches, no difference for richness – or even the opposite pattern for abundance – was observed in pine branches. A significant inter-strata dissimilarity was revealed in all datasets. Each stratum harbored specialist taxa. Exclusive canopy species accounted for 20–40% of all species. In accordance with dissimilarity partitioning, arboreal saproxylic beetle communities were not just nested subsets of ground assemblages.
It is likely that microhabitat requirements, food availability and other non-resource-based factors (microclimate preference, species interactions) drive the stratification of beetle assemblages.
Our results lend support (i) to the recommendation of a multi-strata sampling strategy for forest insects and (ii) to management practices in favour of valuable canopy micro-habitats.
Deadwood is widely recognized to be an important issue for biodiversity conservation in forest ecosystems. Establishing guidelines for its management requires a better understanding of relationships ...between woody debris characteristics and associated species assemblages. Although deadwood diameter has been identified as an important factor predicting occurrence of many saproxylic species, the boundary between small and large diameter has not yet been precisely defined. In commercial forests, it is also of critical importance to know which diameter is large enough to host the beetle species associated with large logs in order to ensure cost-effectiveness of biodiversity conservation measures. We investigated the differences in saproxylic beetle assemblages among four different diameter classes of downed woody oak and maritime pine debris, in France. Beetles were sampled using in situ emergence traps. The diameter of deadwood pieces ranged from 1 to 40 cm. No patterns of nestedness associated with the gradient of diameter size were identified for either tree species. More indicator saproxylic species were observed in large logs and branches than in small logs. A clear distinction appeared in assemblage composition around the 5-cm diameter threshold whereas no similar pattern occurred around the 10 cm value, i.e. the classical threshold used in forestry to distinguish fine woody debris from coarse woody debris. For both tree species, the mean body length of beetles increased with the diameter of deadwood suggesting that the quantity of available resources per piece may constitute a limiting factor for large beetle species. This study confirms that not only large deadwood pieces are relevant for saproxylic biodiversity conservation but also the smallest pieces. Therefore, forest managers would be well advised to maintain a high diversity of deadwoods to maintain saproxylic biodiversity.
Marolia alicantina sp. nov. (Coleoptera: Melandryidae) from eastern Spain is described and illustrated. All specimens were collected using window traps on Quercus rotundifolia Lamarck, 1785 ...(Fagaceae) in the Carrascar de la Font Roja Natural Park (Alicante, Spain). M. alicantina sp. nov. is the only European Marolia having erect setae on the elytra and pronotum. M. alicantina resembles M. grandis Peyerimhoff, 1971 from north Africa, from which it can distinguished by the denser punctuation of the pronotum, shape of the base of the pronotum and shape of the aedeagus. Furthermore, unpublished records for other Marolia species are presented in this paper; in particular M. purkynei Mařan, 1933 is recorded for the first time in Croatia and Greece. The authors had the chance to study six specimens, subsequently labelled as syntypes, of the M. purkynei type series. The location of the remaining possible syntype remains unknown.
The study of insects inhabiting basal hollow trees presents a methodological challenge inducing the fact that there is very little research done on fauna of this habitat. Many endangered saproxylic ...species only develop in cavities located at ground level. One of the most emblematic species of the kind is the Violet Click Beetle (Limoniscus violaceus), included in Annex II of the UE “Habitats” Directive. Surveys have been conducted in five Natura 2000 areas using a new method to monitor L. violaceus: the emergence traps. A total of 376 beetle species, including 239 saproxylics, have been identified. Five are considered threatened and are registered on the European Red List of saproxylic beetles and three are included in Annex II of the “Habitats” Directive. Among 191 trees studied, 33 revealed the presence of L. violaceus. Sampling efforts required to detect at least one specimen have been evaluated. Our results show that sampling a minimum of 20 hollow trees in April and May with emergence traps is recommended to obtain a meaningful survey on the presence of the Violet Click Beetle.
Global warming and land-use change are expected to be additive threats to global diversity, to which insects contribute the highest proportion. Insects are strongly influenced by temperature but also ...require specific habitat resources, and thus interaction between the two factors is likely. We selected saproxylic beetles as a model group because their life cycle depends on dead wood, which is highly threatened by land use. We tested the extent to which higher temperatures compensate for the negative effects of low amounts of dead wood on saproxylic beetle species richness (Temperature–Dead wood compensation hypothesis) on both a macroclimate and a topoclimate scale (north- and south-facing slopes). We analyzed 1404 flight-interception trap catches across Europe to test for interaction effects of temperature and dead-wood amount on species richness. To experimentally test our findings from the activity trap data, we additionally reared beetles from 80 bundles of dead wood initially exposed at high and low elevations. At the topoclimate scale, we analyzed trap catches and reared beetles from dead wood exposed in 20 forest stands on south-facing and north-facing slopes in one region. On the macroscale, both temperature and dead-wood amount positively affected total and threatened species richness independently, but their interaction was significantly negative, indicating compensation. On both scales and irrespective of the method, species richness decreased with temperature decline. Our observation that increasing temperature compensates for lower amounts of dead wood has two important implications. First, managers of production forests should adapt their dead-wood enrichment strategy to site-specific temperature conditions. Second, an increase in temperature will compensate at least partially for poor habitat conditions in production forests. Such a perspective contrasts the general assumption of reinforcing impacts of global warming and habitat loss on biodiversity, but it is corroborated by recent range expansions of threatened beetle species.
Identification of forest stands with priority for the conservation of biodiversity is of particular importance in landscapes with a long cultural and agricultural history, such as Central Europe. A ...group of species with a high indicator value for the naturalness of forest ecosystems are saproxylic insects. Some of these species, especially within the order Coleoptera, have been described as primeval forests relicts. Here, we compiled a list of 168 “primeval forest relict species” of saproxylic beetles based on expert knowledge. These species can serve as focal and umbrella species for forest conservation in Central Europe. They were selected because of their dependence on the continuous presence of primeval forest habitat features, such as over-mature trees, high amounts of dead wood, and dead wood diversity, as well as their absence in managed Central European forests. These primeval forest relict species showed a moderately strong clumping pattern within the phylogeny of beetles, as indicated by phylogenetic signal testing using the
D
-statistic. When we controlled for phylogenetic relatedness, an ordinal linear model revealed that large body size and preference for dead wood and trees of large diameter are the main characteristics of these species. This list of species can be used to identify forest stands of conservation value throughout Central Europe, to prioritize conservation and to raise public awareness for conservation issues related to primeval forests.
Understanding the processes that shape biodiversity patterns is essential for ecosystem management and conservation. Local environmental conditions are often good predictors of species distribution ...and variations in habitat quality usually positively correlate to species richness. However, beside habitat limitation, species presence-absence may be constrained by dispersal limitation. We tested the relative importance of both limitations on saproxylic beetle diversity, using forest continuity as a surrogate for dispersal limitation and stand maturity as a surrogate for habitat limitation. Forest continuity relies on the maintenance of a forest cover over time, while stand maturity results in the presence of old-growth habitat features. Forty montane beech-fir forests in the French pre-Alps were sampled, under a balanced sampling design in which forest continuity and stand maturity were crossed. A total of 307 saproxylic beetle species were captured using flight-interception traps and Winkler–Berlese extractors. We explored the response of low- versus high-dispersal species groups to forest continuity and stand maturity. Saproxylic beetle diversity increased significantly with stand maturity and was mostly influenced by variables related to deadwood diversity at the stand scale and suitable habitat availability at the landscape scale. Surprisingly, no evidence of dispersal limitation was found, as diversity patterns were not influenced by forest continuity and associated variables, even for low-dispersal species. Our study demonstrates that in an unfragmented forest landscape, saproxylic beetles are able to colonize recent forests, as long as local deadwood resources are sufficiently diversified (e.g. tree species, position, diameter and/or decay stage).
Macroecologists seek to identify drivers of community turnover (
-diversity) through broad spatial scales. However, the influence of local habitat features in driving broad-scale
-diversity patterns ...remains largely untested, owing to the objective challenges of associating local-scale variables to continental-framed datasets. We examined the relative contribution of local- versus broad-scale drivers of continental
-diversity patterns, using a uniquely suited dataset of cave-dwelling spider communities across Europe (35-70° latitude). Generalized dissimilarity modelling showed that geographical distance, mean annual temperature and size of the karst area in which caves occurred drove most of
-diversity, with differential contributions of each factor according to the level of subterranean specialization. Highly specialized communities were mostly influenced by geographical distance, while less specialized communities were mostly driven by mean annual temperature. Conversely, local-scale habitat features turned out to be meaningless predictors of community change, which emphasizes the idea of caves as the human accessible fraction of the extended network of fissures that more properly represents the elective habitat of the subterranean fauna. To the extent that the effect of local features turned to be inconspicuous, caves emerge as experimental model systems in which to study broad biological patterns without the confounding effect of local habitat features.
Saproxylic insect communities inhabiting tree hollow microhabitats correspond with large food webs which simultaneously are constituted by multiple types of plant-animal and animal-animal ...interactions, according to the use of trophic resources (wood- and insect-dependent sub-networks), or to trophic habits or interaction types (xylophagous, saprophagous, xylomycetophagous, predators and commensals). We quantitatively assessed which properties of specialised networks were present in a complex networks involving different interacting types such as saproxylic community, and how they can be organised in trophic food webs. The architecture, interacting patterns and food web composition were evaluated along sub-networks, analysing their implications to network robustness from random and directed extinction simulations. A structure of large and cohesive modules with weakly connected nodes was observed throughout saproxylic sub-networks, composing the main food webs constituting this community. Insect-dependent sub-networks were more modular than wood-dependent sub-networks. Wood-dependent sub-networks presented higher species degree, connectance, links, linkage density, interaction strength, and were less specialised and more aggregated than insect-dependent sub-networks. These attributes defined high network robustness in wood-dependent sub-networks. Finally, our results emphasise the relevance of modularity, differences among interacting types and interrelations among them in modelling the structure of saproxylic communities and in determining their stability.
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