I det här kapitlet betonar vi gruppdiskussioners betydelse för att aktivera studenter och gynna deras lärande. Undervisningen på kursen "Evolution" bedrevs omväxlande i traditionell undervisningssal och i ALC. Tyngdpunkten på kursen ligger på studenternas gruppdiskussioner. Fokus i kapitlet ligger på de aktiviteter som studenterna genomför i ALC.

When assessing changes in populations of species it is essential that the methods used to collect data have some level of precision and preferably also good accuracy. One commonly used method to collect pollinators is colour pan-traps, but this method has been suggested to be biased by the abundance of surrounding flowers. The present study evaluated the relationship between pan-trap catches and the frequency of flowers on small (25 m2) and large (2-6 ha) spatial scales. If pan-traps work well, one should assume a positive relationship, i.e. more insects caught when they have more food. However, in contrast, we found that catches in pan-traps were often negatively affected by flower frequency. Among the six taxa evaluated, the negative bias was largest in Vespoidea and Lepturinae, while there was no bias in solitary Apoidea (Cetoniidae, Syrphidae and social Apoidea were intermediate). Furthermore, red flowers seemed to contribute most to the negative bias. There was also a tendency that the negative bias differed within the flight season and that is was higher when considering the large spatial scale compared to the small one. To conclude, pan-trap catches may suffer from a negative bias due to surrounding flower frequency and colour. The occurrence and magnitude of the negative bias was context and taxon dependent, and therefore difficult to adjust for. Thus, pan-traps seems less suited to evaluate differences between sites and the effect of restoration, when gradients in flower density is large. Instead, it seems better suited to monitor population changes within sites, and when gradients are small.

Methods 

STUDY SITES: Data were collected in 2015 in the province of Östergötland, southern Sweden. The landscape in the study area consists mainly of coniferous forest, but there are also bogs, lakes, small patches of seminatural grasslands and arable fields. Twelve clear-cuts were selected (2-6 ha and logged 4-6 years prior). Six of them had been marked as coniferous forests on maps from the 1870s when the other six were marked as meadows. Clear-cuts on former meadows have higher amounts of herbs than clear-cuts which were formerly forests. Hence, our site selection strategy covered the wide range of flower abundances that occur on clear-cuts in the study area. 

PAN-TRAPS: The pans used to collect pollinators were painted in one of the following colours: blue, white and yellow with UV-reflecting-colour (Soppec, Sylva mark fluo marker, Nersac, France). The pans had a diameter of 8.7 cm, a volume of 0.5 L and were filled with non-toxic propylene glycol (40% concentration), to conserve the pollinators and to decrease the surface tension. A small opening (4 mm in diameter) at the top of each bowl was made to ensure that rainwater could drain. One set of pan-trap consisted of three pans, one in each colour, placed on a steel stick.

Four sets of pan-traps were placed in each clear-cut, in the same height as the vegetation and in places that were considered representative for the clear-cut. During the main flight period of most pollinating insects, three sampling periods were conducted: in the beginnings of June, beginning of July and beginning of August. Each period lasted for one week and had at least some days with more than 17°C and wind velocity less than four on the Beaufort scale. The pans were covered with caps between collecting periods. When a new collecting period started, some sets of pan-traps were moved - at most 30 cm - or some of the vegetation was removed to prevent overgrowth.

In total there were 48 set of pan-traps collecting during each period, but a few sets of pan-traps had been knocked down by animals and were therefore excluded (1, 1 and 2 during the first, second and third period, respectively). In addition, a single blue pan went missing during the second period. 

Four taxonomic groups dominated the catches – Aculeata, Lepturinae, Cetoniidae and Syrphidae – and they were identified to species-level. Aculeata was subdivided as solitary Apoidea, social Apoidea (Bombus spp. Apis mellifera), and Vespoidea (including one species of Chrysidoidea). Other insects caught, that are not identified, were mainly small Coleoptera, small Lepidoptera and Symphyta.

FLOWER FREQUENCY: The clear-cuts were photographed in conjunction with each collecting period to estimate flower frequency. A 1 m2 square was placed on the ground and photographed from above (from c 160 cm height). Around each pan-trap, at least 25 such 1 m2 squares were photographed reflecting small-scale flower abundance (“trap scale”). An additional at least 100 pictures were systematically distributed along transects over the whole clear-cut reflecting large-scale (“clear-cut scale”) flower abundance. Photos were taken during each collecting period, or at most 5 days before or after. 

All 8048 photos taken were inspected to see if they held flowers within the 1-m2 square and if so of which colours (red, yellow, blue and white). The frequencies of colours (i) around set of pan-traps, and (ii) on clear-cuts were expressed as the odds for the colour occurring in a square metre plot: (0.5+p)/(0.5+(1-p)), where p=frequency of photos with the colour. Also, we calculated the odds for flower of any colour occurring in a plot.

Both agricultural intensification and abandonment have led to the loss of European semi-natural grasslands. Nature conservation management measures like mowing are essential for preserving the biodiversity of remaining grasslands. However, there are no conclusive results from studies examining effects of different mowing frequencies across Europe. To fill this gap, we evaluated data from European studies comparing mowing frequencies to determine which are the most beneficial from a nature conservation viewpoint. We searched literature for short- and long-term studies comparing the effects of different mowing frequencies on outcome measures relevant for biodiversity conservation. We found 29 relevant studies where mowing once per year was compared to higher or lower mowing frequencies. The studies covered various grassland types and organisms. The effects were analysed using response ratios, where mowing once per year, i.e. the traditional mowing frequency in semi-natural grasslands, was compared to mowing every fifth, third or second year and mowing two, three or four times a year. Overall, we found similar effects of the different mowing frequencies on the biodiversity of flora and fauna. More frequent mowing generally had a more positive effect, but differences between frequencies were small. Effects were habitat-specific, differing between site and study conditions. For example, a higher mowing frequency was more beneficial in more productive grasslands. These results suggest that in most European semi-natural grasslands, mowing less frequently is a way of using the limited funds available for management more efficiently while still maintaining grassland conservation values, but e.g. site productivity must be considered when determining a suitable mowing frequency.

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.

To maintain the high biodiversity of semi-natural grasslands, management by grazing or mowing isneeded. Given the limited resources and few remaining areas, the best management method should beused. However, only a few studies comparing the effects of mowing and grazing on grassland biodiversityexists. Therefore, the goal of the present review was to extract as much data as possible from theliterature and evaluate them using a meta-analysis approach. We searched scientific and grey literaturefor studies comparing the effects of grazing and annual mowing on outcomes relevant for biodiversityconservation. We identified 35 relevant studies on grazing and annual mowing that provided datasuitable for the meta-analysis. We found that grazing generally had a more positive effect on theconservation value of semi-natural grasslands compared to mowing, but effect sizes were generally smallto moderate for most contrasts. Furthermore, effects varied across some grassland characteristics e.g. fordifferent grassland types, with grazing and mowing having a similar effect or mowing having a morepositive effect in certain cases. Our results suggest, that in most cases grazing should be the preferredmanagement method when managing for grassland conservation.

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.

The Mediterranean basin exhibits a multitude of forest habitats affected by former and current exploitation and management. Recent afforestation programs have resulted in an increase in the proportion of coniferous trees, while oak stands, formerly utilized for coppicing and grazing, are abandoned or converted into coniferous plantations. The loss of oak stands might negatively affect birds dependent upon broadleaved forests. Studies confirming or rejecting that statement are scarce, particularly in the eastern part of the region. Using a study area in southwestern Turkey we applied a guild-based approach to investigate how pine and oak stands across a chronosequence differ in their capacity to support forest bird assemblages. Variables describing the vegetation were sampled to characterize the stands and relate bird assemblages to stand structure. Bird abundance and species richness was positively associated with age for both stand types. Richness and diversity was highest in oak stands, while there were no differences in bird abundance between the two forest types. Pine stands supported a different bird species composition compared to oak stands of the same age. Stand age and structure, rather than forest type, held the highest explanatory powers for bird assembly structure. Primary cavity-nesters and ground-nesters were more abundant in oak stands, possibly reflecting differences in stand structure and resource distribution. To support these birds with suitable habitats, oaks stands need conservation. Management practices in pine stands should strive for increasing the amount of old trees and retain vegetation in the understory to benefit breeding birds.