A comparison of three methods to survey saproxylic beetles in hollow oaks

One of the most endangered assemblages of species in Europe is insects associated with old trees. For that reason there is a need of developing methods to survey this fauna. This study aims at comparing three methods — window trapping, pitfall trapping and wood mould sampling — to assess species richness and composition of the saproxylic beetle fauna in living, hollow oaks. We have used these methods at the same site, and to a large extent in the same trees. Useful information was obtained from all methods, but they partially target different assemblages of species. Window trapping collected the highest number of species. Pitfall trapping collected beetles associated with tree hollows which rarely are collected by window traps and therefore it is profitable to combine these two methods. As wood mould sampling is the cheapest method to use, indicator species should preferrably be chosen among species which are efficiently collected with this method

The influence of forest regrowth, original canopy cover and tree size on saproxylic beetles associated with old oaks

Abandoned management has caused many sites with free-standing, large oaks (Quercus robur) to become more shaded. This study shows how forest regrowth affects beetle species associated with old oaks in south-eastern Sweden. Beetles were trapped by pitfall traps placed in hollows and window traps placed near hollows in oak trunks in pasture woodlands. We assessed the influence of forest regrowth, tree size and original canopy cover on the species richness of saproxylic beetles (a total of 120 species identified) and the occurrence of 68 saproxylic beetle species in particular. Species richness was greatest in stands with large, free-standing trees. Large girth as well as low canopy cover increased frequency of occurrence for several species. Forest regrowth was found to be detrimental for many beetle species. As most localities with endangered beetles living in old oaks are small and isolated, ongoing management and the restoration of abandoned pasture woodlands should have a high priority in nature conservation

Bargaining Around the TRIPS Agreement: The Case for Ongoing Public-Private Initiatives to Facilitate Worldwide Intellectual Property Transactions. A Comment on the Paper Presented by David Lange and J.H. Reichman

Light trapping is an ideal method for surveying nocturnal moths, but in the absence of standardised survey methods effects of confounding factors may impede interpretation of the acquired data. We explored the influence of weather, time of year, and light source on nightly catches of macro moths in light traps, and compared four strategies for sampling by estimating observed species richness using rarefaction. We operated two traps with different light sources for 225 consecutive nights from mid-March to the end of October in eastern Germany in 2011. In total, 49 472 individuals of 372 species were recorded. Species richness and abundance per night were mainly influenced by night temperature, humidity and lamp type. With a limited sample size (less than10 nights) it was slightly better to concentrate sampling on the warmest summer nights, but with more sampling nights it was slightly better to sample during the warmest nights in each month (March to October). By exploiting the higher moth activity during warm nights and an understanding of the species phenology, it is possible to increase the number of species caught and reduce effects of confounding abiotic factors

Epiphyte metapopulation dynamics are explained by species traits, connectivity, and patch dynamics

The colonization-extinction dynamics of many species are affected by the dynamics of their patches. For increasing our understanding of the metapopulation dynamics of sessile species confined to dynamic patches, we fitted a Bayesian incidence function model extended for dynamic landscapes to snapshot data on five epiphytic lichens among 2083 mapped oaks (dynamic patches). We estimate the age at which trees become suitable patches for different species, which defines their niche breadth (number of suitable trees). We show that the colonization rates were generally low, but increased with increasing connectivity in accordance with metapopulation theory. The rates were related to species traits, and we show, for the first time, that they are higher for species with wide niches and small dispersal propagules than for species with narrow niches or large propagules. We also show frequent long-distance dispersal in epiphytes by quantifying the relative importance of local dispersal and background deposition of dispersal propagules. Local stochastic extinctions from intact trees were negligible in all study species, and thus, the extinction rate is set by the rate of patch destruction (tree fall). These findings mean that epiphyte metapopulations may have slow colonization-extinction dynamics that are explained by connectivity, species traits, and patch dynamics

The influence of tree age and microhabitat quality on the occurrence of crustose lichens associated with old oaks

Questions: How do tree age, microhabitat characteristics and epiphytic competitors affect the occurrence of crustose lichens associated with old oaks? How do microhabitat characteristics and microclimate affect the cover of competitors (bryophytes and macrolichens)? How do microhabitat characteristics cor¬relate with microclimatic variables? Location: Southeast Sweden. Methods: Eight crustose lichen species were surveyed on 165 Quercus robur trees, 17-478 years old, at three study sites. The occurrence patterns of these species were examined at two spatial scales: among trees and within trees. Occurrence patterns within trees were examined in 10 cm × 10 cm plots at all four cardinal aspects at different heights from 0.5 to 4.5 m above the ground. Results: At the tree level, age-related factors were the most important predictors of species occurrence. All species were more frequent on trees > 100 years than on younger trees. At the plot level, the frequency of occurrence increased with increasing bark crevice depth. The frequencies of all study species de¬creased with increasing cover of bryophytes. Bryophytes were in turn more frequent in plots that were exposed to rainwater and showed a low evaporation rate. Patches most exposed to rainwater were directed upwards, and the lowest evaporation rates occurred on the northern side of the trunks. Conclusions: For many crustose lichens the association with old oak trees seems at least partly to depend on their preference for the deep bark crevices that only occur on old trees. Trees represent epiphyte habitat patches that differ in size due to within-tree variability in habitat quality, such as bark crevice depth and microclimate. This study shows that variability at a finer scale, within habitat patches, contribute to explain species occurrence patterns at habitat patch level

Habitat associations and occupancy patterns of burnet moths (Zygaenidae) in semi-natural pastures in Sweden

Burnets were surveyed in 100 semi-natural pastures in the province of Östergötland, southeastern Sweden. We analysed the presence/absence of burnets in relation to habitat characteristics, and species richness of butterflies and plants. Five species were found (Adscita statices, Zygaena osterodensis, Z. viciae, Z. filipendulae and Z. lonicerae), all occurring in 33%–36% of the localities. Among these, four are nationally red-listed. More species were found on (1) large semi-natural pastures, compared with small, (2) low- to medium-grazed semi-natural pastures, compared with heavily grazed, and (3) open semi-natural pastures, compared with wooded. A. statices and Z. viciae had a higher frequency of occupancy at localities surrounded by a large density of pastures, but the occurence of the other species did not rely on this variable. The number of burnet species per locality was positively correlated with the number of butterfly species, and slightly positively correlated with species richness of plants. The difference in species richness among burnets, butterflies and plants may be explained by different responses to grazing pressure; the species richness of burnets and butterflies peaked in localities with a lowgrazing pressure, while species richness of plants was unaffected by grazing. As burnets are easily surveyed and indicate a high butterfly-species richness, they may be suitable indicators of species richness of pastures. As uniform management with heavy grazing is detrimental for burnets and for many butterflies, it should be avoided at localities with a speciesrich fauna

The usefulness of surrogates in biodiversity conservation: a synthesis.

Preserving biodiversity requires extensive information on species distributions and effectiveness of conservation actions. A surrogate approach, where a small number of species act as surrogates for broader groups of species, can simplify this task. Types of surrogates include indicator, umbrella, keystone and flagship species, and using diversity of higher taxonomic levels to represent species diversity. An overview of the empirical evidence of the usefulness of surrogates as a conservation tool is missing. We synthesised knowledge on if and when surrogate species are useful by systematically searching for meta-analyses and literature reviews assessing this. Results from 34 reviews revealed weak correlations between diversity of indicator species and other species and that umbrella species were not consistently useful for prioritising conservation actions. However, diversity of higher taxonomic levels can be representative of species diversity. No reviews have assessed the usefulness of keystone or flagship species. Thus, surrogate taxa often do not represent biodiversity or threatened species, and conservation actions aimed at surrogates might not necessarily benefit other species. However, surrogates are more likely to be useful when using a higher-taxon approach, when strong ecological similarities exists between a surrogate and other species, when surrogates are used at regional or landscape rather than local scales, and when using sets of multiple species as surrogates. As some use of surrogate species will always be necessary, surrogates should be carefully selected and their usefulness and cost-effectiveness should be assessed, including the risk that conservation actions aimed at that surrogate have unintended effects on other species

Microclimate in hollow trees and how it affects an inhabiting beetle species, Osmoderma eremita

Studies of species' responses to microclimatic conditions have increased our understanding of their habitat requirements and possible responses to climate warming. However, little is known about the role of microclimate for insects inhabiting hollow trees. We explored the relationship between tree characteristics and microclimate, and analysed how the microclimate in tree-hollows affects the occurrence and body size of an endangered beetle species, Osmoderma eremita. We placed temperature data-loggers in wood mould (= loose material in tree-hollows) and surveyed O. eremita in 47 hollows in oak pastures in south-eastern Sweden. We found that tree characteristics previously known to be associated with occurrence of beetle species confined to tree-hollows (larger diameters, more wood mould, entrances higher up, and not directed upwards) tend to decrease moisture and moisture variation, while their effects on temperature and temperature fluctuations differ during different seasons. This indicates that microclimatic conditions are important for beetles in hollow trees, and many specialised species seem to avoid conditions that are too moist. O. eremita occurred more frequently in trees with a warmer and more stable microclimate, while adult body size decreased with a warmer microclimate. A positive effect of a warmer microclimate was expected, since the study was done near the northern margin of the species' range. O. eremita is confined to living in hollow trees, which may be due to the microclimate there being more stable in comparison to both the ambient climate and the microclimate in standing and downed dead wood

Microclimatic conditions mediate the effect of deadwood and forest characteristics on a threatened beetle species, Tragosoma depsarium

While climate change has increased the interest in the influence of microclimate on many organisms, species inhabiting deadwood have rarely been studied. Here, we explore how characteristics of forest stands and deadwood affect microclimate inside deadwood, and analyse how this affects wood-living organisms, exemplified by the red-listed beetle Tragosoma depsarium. Deadwood and forest variables explained much of the variation in temperature, but less of the variation in moisture within deadwood. Several variables known to influence habitat quality for deadwood-dependent species were found to correlate with microclimate. Standing deadwood and an open canopy generates warmer conditions in comparison to downed logs and a closed canopy, and shaded, downed and large-diameter wood have higher moisture and more stable daily temperatures than sun-exposed, standing, and small-diameter wood. T. depsarium occupancy and abundance increased with colder and more stable winter temperatures, and with higher spring temperatures. Consistently, the species occurred more frequently in deadwood items with characteristics associated with these conditions, i.e. downed large-diameter logs occurring in open conditions. Conclusively, microclimatic conditions were found to be important for a deadwood-dependent insect, and related to characteristics of both forest stands and deadwood items. Since microclimate is also affected by macroclimatic conditions, we expect species' habitat requirements to vary locally and regionally, and to change due to climate warming. Although many saproxylic species preferring sun-exposed conditions would benefit from a warmer climate per se, changes in species interactions and land use may still result in negative net effects of climate warming

Relative importance of habitat characteristics at multiple spatial scales for wood-dependent beetles in boreal forest

Species distributions are influenced by habitat conditions and ecological processes at multiple spatial scales. An understanding of the importance of habitat characteristics at different spatial scales is important when developing biodiversity conservation measures.We investigated the effect of habitat characteristics or amount at three spatial scales on the occurrence of saproxylic (=dead wood-dependent) beetles.Saproxylic beetles were sampled under the bark of dead wood in a managed forest landscape in central Sweden. We modelled the occurrence probability in dead wood items of 44 species (all species occurring in > 2 % of the items), based on dead wood item characteristics, forest stand characteristics, and habitat connectivity (i.e. area of potentially suitable forest stands in the surrounding of each stand), using hierarchical Bayesian regression.For the majority of species, dead wood item characteristics (especially tree species and whether standing or downed) were more important than measured stand characteristics and habitat connectivity. Whether the stands were clear-cuts, mature forests, or reserves affected some species, whereas the stand-level amount of dead wood per hectare was not important for any species. Habitat connectivity improved the occurrence models for about a half of the species, but there were both positive and negative relationships, and they were generally weak.Forest management should include creation and retention of a high diversity of dead wood to sustain habitat for all species. In a forest-dominated landscape, the spatial distribution of dead wood is of little importance for common saproxylic beetle species