Old living oaks (Quercus robur) are known as a very species-rich habitat for saproxylic beetles, but it is less clear to what extent such veteran trees differ from an even rarer feature: downed trunks of large oaks. In this study, we set out to sample this habitat, using window traps, with two aims: (1) to describe the variation of assemblages among downed trunks of different type and (2) to compare beetles on downed oaks with data from veteran standing trees. The results showed that trunk volume and sun exposure better explained assemblages as well as species numbers on downed trunks than did decay stage. Furthermore, species classified as facultative saproxylic species showed weak or no differentiation among downed trunks. Species with different feeding habits showed no apparent differentiation among downed trunks. Furthermore, species composition on dead, downed oak trunks differed sharply from that of living, veteran oaks. Wood or bark feeders were more common on veterans than downed trunks, but there was no difference for those species feeding on fungi or those feeding on insects and their remains. In conclusion, for a successful conservation of the saproxylic beetle fauna it is important to keep downed oak trunks, and particularly large ones, in forest and pastures as they constitute a saproxylic habitat that differs from that of living trees.

Many saproxylic species are threatened in Europe because of habitat decline.Hollow trees represent an important habitat for saproxylic species. Artificial habitats mayneed to be created to maintain or increase the amount of habitat due to natural habitat decline.This study investigated the extent to which saproxylic beetles use artificial habitats in woodenboxes. The boxes were placed at various distances (0–1800 m) from known biodiversityhotspots with hollow oaks and studied over 10 years. Boxes were mainly filled with oak sawdust, oak leaves, hay and lucerne flour. In total, 2170 specimens of 91 saproxylic beetlespecies were sampled in 43 boxes. The abundance of species associated with tree hollows,wood rot and animal nests increased from the fourth to the final year, but species richnessdeclined for all groups. This study shows that wooden boxes can function as saproxylicspecies habitats. The artificial habitats developed into a more hollow-like environment duringthe decade long experiment with fewer but more abundant tree hollow specialists.

With steadily shrinking areas of species-rich semi-natural grasslands in Europe, the management of theremaining fragments becomes ever more crucial for the preservation of key elements of biodiversity inthe agricultural landscape. Detailed knowledge about species-wise, as well as group-wise, relationshipscan provide guidelines for conservation management and a basis for predictions about differentmanagement scenarios. In the present study, we related the occurrence of species of bumblebees (N = 12),butterflies (31) and day-flying moths (4) and their total richness in 424 sites in southern Sweden to threegrass sward attributes, (i)flower abundance, (ii) height of the grass sward and (iii) within-site variation inheight of vegetation. The abundance of nectar-bearingflowers proved overall the best predictor ofrichness and in most of the occurrence-based species-wise models. However, both high grass swardheight and high variation in grass sward height contributed significantly to species richness andoccurrence of individual species. There was a tendency for bumblebees to respond less positively toflower abundance and vegetation height than butterflies and moths. One expectation was that grasslandspecialists, red-listed species, or species decreasing in other part of Europe, would be more responsive totall vegetation orflower abundance but there was no support for this in the data. Hence, managementstrategies that promote common species will also benefit all, or most of, the rare ones as well.

Synanthedon vespiformis L. (Lepidoptera:Sesiidae) is considered a rare insect in Sweden, discoveredin 1860, with only a few observations recorded until a sexpheromone attractant became available recently. This studydetails a national survey conducted using pheromones as asampling method for this species. Through pheromonetrapping we captured 439 specimens in Southern Sweden at77 sites, almost tripling the number of previously reportedrecords for this species. The results suggest that S. vespiformisis truly a rare species with a genuinely scattereddistribution, but can be locally abundant. Habitat analyseswere conducted in order to test the relationship betweenhabitat quality and the number of individuals caught. InSweden, S. vespiformis is thought to be associated with oakhosts, but our attempts to predict its occurrence by theabundance of oaks yielded no significant relationships. Wetherefore suggest that sampling bias and limited knowledgeon distribution may have led to the assumption that thisspecies is primarily reliant on oaks in the northern part ofits range, whereas it may in fact be polyphagous, similar toS. vespiformis found as an agricultural pest in Central andSouthern Europe. We conclude that pheromones canmassively enhance sampling potential for this and otherrare lepidopteran species. Large-scale pheromone-basedsurveys provide a snapshot of true presences and absencesacross a considerable part of a species national distributionrange, and thus for the first time provide a viable means ofsystematically assessing changes in distribution over timewith high spatiotemporal resolution.

Fire-favoured insects are difficult to sampleexcept opportunistically after forest fires. Here, we tested ifsmoke from a small fire could be an efficient way to samplesuch insects. Insects were sampled over ca. 10 h hours, byhand-picking and netting on screens put up around the fire.Two specimens of the rare and redlisted Hormopeza spp.(Diptera, Empididae) were caught. Large numbers([20,000) of Microsania spp. (Diptera, Platypezidae) werecaught, but none in the absence of smoke. The numbers ofMicrosania spp. clearly peaked in late afternoon, and ashort sampling period would be sufficient if targeting onlythis taxon. Of the almost 200 species of Coleoptera, 17 %were considered as fire-favoured, contributing 9 % of thespecimens, suggesting low efficiency of the method for thisgroup. Using 23 sites differing in fire history, catches ofMicrosania spp. were unaffected by numbers and area offorest fire (preceding 5 years and within 10 km radius overthe sampling sites). In contrast, there was a weak trend forthe proportion of fire-favoured Coleoptera to increase withincreasing number of fires. To conclude, smoke as producedin our study can clearly attract fire-favoured Diptera,but smoke had only a weak effect on fire-favoured Coleopterain the study area. It is still likely that selectivelypicking specimens of species attracted to smoke is a morecost-efficient method than using, e.g., Malaise traps thatcatch indiscriminately.

Butterfly conservation in Europe is mainly focused on well-defined grassland habitat patches. Such anapproach ignores the impact of the surrounding landscape, which may contain complementary resourcesand facilitate dispersal. Here, we investigated butterfly species richness and abundance in a habitatnormally regarded as unsuitable matrix: production forestry clear-cuts. Butterflies were recorded in 48clear-cuts in southern Sweden differing with regards to the time since clear-cutting and land-use history(meadow or forest based on historical maps from the 1870s). All clear-cuts had been managed as productionforests for at least 80e120 years. A total of 39 species were found in clear-cuts of both land-usehistories, but clear-cuts with a history as meadow had on average 34% higher species richness and 19%higher abundance than did clear-cuts with a history as forest. No effect of the time since clear-cuttingwas found, irrespective of land-use history, which was likely due to the narrow timespan sampled (<8years). The absence of temporal effect suggests that clear-cuts may provide butterflies with valuableresources for 10e15 years. Assuming a 100 year forest rotational cycle, this means that 10e15% of thetotal forested area are made up by clear-cuts valuable to butterflies, which corresponds to an area aboutfour times as large as that of species-rich semi-natural grasslands. The study illustrates the importance ofconsidering land-use legacies in ecological research and question the landscape-ecological view thatclear-cuts make up an unsuitable matrix for butterflies. Moreover, forest conservation management withspecial attention to land-use history may increase the quality of the landscape, thus facilitating butterflymetapopulation persistence. Given their large area and assets of nectar and host plant resources, clearcutsmust be considered as a butterfly habitat in its own right. Being a man-made environment withshort history, we might call it a neo-habitat.

Losses of both habitat area and connectivity have been identified as important drivers of species richness declines, but littletheoretical and empirical work exists that addresses the effect of fragmentation on relative commonness of highly mobilespecies such as pollinating insects. With a large dataset of wild bee and butterfly abundances collected across Europe,we first tested the effect of habitat area and connectivity on evenness in pollinator communities using a large array ofindexes that give different weight to dominance and rarity. Second, we tested if traits related to mobility and diet breadthcould explain the observed evenness patterns. We found a clear negative effect of area and a weaker, but positive effectof connectivity on evenness. Communities in small habitat fragments were mainly composed of mobile and generalistspecies. The higher evenness in small fragments could thereby be generated by highly mobile species that maintain localpopulations with frequent inter-fragment movements. Trait analysis suggested an increasing importance of dispersalover local recruitment, as we move from large to small fragments and from less to more connected fragments. Speciesrichness and evenness were negatively correlated indicating that the two variables responded differently to habitat areaand connectivity, although the mechanisms underlying the observed patterns are difficult to isolate. Even though habitatarea and connectivity often decrease simultaneously due to habitat fragmentation, an interesting practical implicationof the contrasting effect of the two variables is that the resulting community composition will depend on the relativestrength of these two processes.

Biodiversity often suff ers from urbanization. In the present study, we focused on how the duration of urbanization aff ects therichness of 17 epiphytic lichen species and their cover on large oaks in urban environments in a city of 100 000 inhabitantsin southeast Sweden. We also surveyed trees in adjacent rural areas, selected to have similar distributions of tree trunkcircumference and surrounding oak density (within 300 m). Lichen richness and cover were lower on urban trees comparedto rural trees. Furthermore, richness and cover decreased with the length of time that urban trees had been surrounded byhouses. Most of the species that were analysed demonstrated a decline in occurrence with respect to the duration of housingdevelopment. Th e reduction in the probability of occurrence varied from 60% ( Calicium viride , Evernia prunastri ), 80%( Chrysothrix candelaris ) to 90% ( Ramalina spp.) during the considered 160-year period of urbanization. Th erefore, even ifvaluable trees survive over the course of development, their lichen biota is likely to become depleted over time.

The rare beetle Elater ferrugineus was sampled at 47 sites in the county of Östergötland, Sweden by meansof pheromone-baited traps to assess its value as an indicator species for hollow oak stands rich in raresaproxylic beetle species. In addition, Osmoderma eremita was also sampled with pheromone baits. Thesedata were then compared against species survey data collected at the same sites by pitfall and windowtraps. Both species co-occur with many Red Listed saproxylic beetles, with E. ferrugineus being a somewhatbetter indicator for the rarest species. The conservation value of a site (measured as Red List pointsor number of Red Listed species) increased with the number of specimens of E. ferrugineus and O. eremitacaught. Accuracy of sampling by means of pheromone trapping turned out to be radically different for thetwo model species. E. ferrugineus traps put out during July obtained full accuracy after only 6 days,whereas O. eremita traps needed to be out from early July to mid-August in order to obtain full accuracywith one trap per site. By using E. ferrugineus, or preferably both species, as indicator species, accuracywould increase and costs decrease for saproxylic biodiversity sampling, monitoring and identificationof hotspots.

Question

The management of species-rich semi-natural grasslands, a fragmented and threatened vegetation type in Europe, involves costs. Mowing is expensive and grazing can be difficult to achieve and maintain for logistical reasons. Is annual spring burning, which is potentially cheaper than mowing and grazing, a viable management tool for species-rich grasslands?

Location

Long-term field trials in 11 grasslands in southern Sweden.

Methods

We calculated the odds for a species being an indicator of good management, an indicator of poor management, or an indicator of nitrogen influence in spring-burned plots, grazed plots and annually mowed plots. Odds ratios contrasting spring-burned plots with grazed plots and spring-burned plots with mowed plots were subjected to meta-analyses in which we compared the odds ratios after 1, 8 and 14 spring burns. For a single trial, we also analysed data after 1, 8, 14, 28 and 39 spring burns.

Results

Compared with mowed and grazed plots, the odds of the four different indicators of good management decreased in spring-burned plots, while the odds for the two indicators of poor management increased. There was no trend in the two indicators of excess nitrogen. Therefore, the conservation value of vegetation in spring-burned plots becomes reduced over time relative to traditional management.

Conclusions

Spring burning is not an appropriate long-term management method if the aim is to maintain the conservation value of the vegetation in traditionally managed semi-natural grasslands.