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Ecological traits of the circumboreal plant Viburnum opulus were examined to improve understanding of the variation of populations occurring in the same biome but on different continents. Seedling development/emergence is shown to be highly similar but some degree of variation was present in other traits, among populations., Background and aims Temperate forests are disjunct in the Northern Hemisphere, having become fragmented from the earlier widespread (Tertiary) boreotropical forest. We asked ‘What are the contemporary patterns of population variation in ecological traits of a Tertiary relict in a macroecological context?’. This issue underpins our understanding of variation in populations occurring in the same biome but on different continents. Methodology We examined characters associated with root and shoot emergences among populations of Viburnum opulus in temperate forests of Asia, North America and Europe. This species has complex seedling emergence extending over several years and requiring various temperature cues. Principal results Populations varied in germination responses and clustered into groups that were only partly related to varietal status. Whereas roots (at warm temperatures) and shoots (following a cold period) simultaneously emerged from seeds of all populations when simulated dispersal occurred in winter, they were delayed in some populations when dispersal occurred in summer. Conclusions Viburnum opulus populations, some separated by 10 300 km, showed high similarity in seedling development and in germination phenology, and we suggest that stabilizing selection has played a key role in maintaining similar dormancy mechanisms. Nevertheless, there was some degree of variation in other germination characters, suggesting local adaptation.

The objectives of this study were to describe the intra-specific variation in herbicide response of weed populations when subjected to new vs. well-established herbicides, and to assess distributions of logLD(50)- and logGR(50)-estimates as a potential indicator for early resistance detection. Seeds of two grass weeds (Alopecurus myosuroides, Apera spica-venti) were collected in southern Sweden, mainly in 2002. In line with the objectives of the study, the collections sites were not chosen for noted herbicide failures nor for detected herbicide resistance, but solely for the presence of the target species. For each species, seedlings were subjected to two herbicides in dose-response experiments in a greenhouse. One herbicide per species was recently introduced and the other had been on the market for control of the species for a decade, with several reports of resistance in the literature. Fresh weight of plants and a visual vigour score were used to estimate GR(50) and LD50, respectively. Resistance to fenoxaprop-P-ethyl in A. myosuroides was indicated by the LD50-estimates to be present in frequencies sufficient to affect the population-level response in 9 of 29 samples, and was correlated to response to flupyrsulfuron, while low susceptibility to isoproturon in A. spica-venti populations was not linked to the response to sulfosulfuron. In the study as a whole, the magnitude of the estimated herbicide susceptibility ranges differed irrespective of previous exposure. No consistent differences were found in the distribution of LD50-estimates for new and "old" herbicides, and normality in the distribution of estimates could not be assumed for a non-exposed sample, even in the absence of an indication of cross-resistance. Original Publication:Liv A Espeby, Hakan Fogelfors and Per Milberg, Susceptibility variation to new and established herbicides: Examples of inter-population sensitivity of grass weeds, 2011, CROP PROTECTION, (30), 4, 429-435.http://dx.doi.org/10.1016/j.cropro.2010.12.022Copyright: Elsevier Science B.V., Amsterdam.http://www.elsevier.com/

Monitoring of butterflies is often directed only towards grassland fauna. Species associated with other habitats, as well as the impact of the surrounding landscape, are often neglected. The aim with this study was, in contrast, to perform and evaluate a landscape-based monitoring method for butterflies in diverse habitats and more specifically to (i) evaluate the impact of environmental variables on butterfly abundance; (ii) compare the distribution of butterflies in different habitats; and (iii) analyse data from the study with the aim of improving the method. Eight randomly placed study sites (750 m x 750 m) located in south-eastern Sweden were used. The vegetation composition (tree cover, percentage of coniferous and deciduous forest, shrubs, dry, mesic, damp and wet land) inside the squares was analysed using aerial photos and habitats along transects were categorised in the field. The butterfly composition varied depending on the landscape composition. Tree cover had the largest impact on butterfly abundance with a negative relationship between abundance and increasing tree cover. The most species-rich habitats were other grasslands (abandoned fields and fallows), clear-cuts, semi-natural grasslands, and bogs, each habitat also harbouring unique species. Clear-cut was the habitat harbouring the highest abundance and other grasslands the highest diversity of butterflies. Semi-natural grasslands, where the nationally based monitoring of butterflies in Sweden currently is being performed, constitutes andlt;1% of the total land area in Sweden, indicating a current bias in monitoring directed towards only a part of the species pool. The landscape-based form of monitoring presented here can, if performed regularly, increase our knowledge of how structural changes of landscape affect butterflies and thereby improve conservation efforts. Original Publication:Dennis Jonason, Per Milberg and Karl-Olof Bergman, Monitoring of butterflies within a landscape context in south-eastern Sweden, 2010, JOURNAL FOR NATURE CONSERVATION, (18), 1, 22-33.http://dx.doi.org/10.1016/j.jnc.2009.02.001Copyright: Elsevier Science B.V., Amsterdamhttp://www.elsevier.com/

Cover estimates by eye is a prevailing method to assess abundance. We examined cover estimates with regard to bias and random variation. Ten observers working with a national forest vegetation survey estimated sixteen 100 m(2)-plots, placed in two different vegetation types. These had similar species composition but were clearly distinguishable in the field. In species-wise analyses, observer bias varied greatly, with Dicranum spp., Vaccinium vitis-idaea and Vaccinium myrtillus having the largest bias. Experience had a surprisingly small impact on variation. Power analysis revealed only small differences between observers in the ability to distinguish the two vegetation types, and little value in averaging the assessments from two, three or four observers. Cover estimates did better than presence/absence data in separating the two vegetation types and multivariate analyses were more powerful than univariate ones. The original publication is available at www.springerlink.com:Johan Bergstedt, Lars Westerberg and Per Milberg, In the eye of the beholder: bias and stochastic variation in cover estimates, 2009, PLANT ECOLOGY, (204), 2, 271-283.http://dx.doi.org/10.1007/s11258-009-9590-7Copyright: Springer Science Business Mediahttp://www.springerlink.com/

In an ecological context, knowledge of intra-species variation in dormancy and germination is necessary both for practical and theoretical reasons. We used four or five seed batches (replicates) of four closely related annuals co-occurring in arable fields in Sweden: Lamium amplexicaule, L. confertum, L. hybridum and L. purpureum. Seeds used for experiments stemmed from plants cultivated on two sites, each site harbouring one population of each species, thereby ensuring similar environmental history of seeds. Seeds were tested for germination when fresh and after three different pre-treatments (cold or warm stratification, or dry storage) for up to 24 weeks. Seeds were also sown outdoors. Despite substantial intra-species variation, there were clear differences between species. The general seed dormancy pattern, i.e. which environmental circumstances that affect dormancy, was similar for all species; dormancy reduction occurred during warm stratification or dry storage. Even though the response to warm stratification indicate a winter annual pattern, successful plants in Sweden were mostly spring emerged. Germination in autumn occurred, but plants survived winters poorly. Consequently, as cold stratification did not reduce dormancy, strong dormancy in combination with dormancy reduction during dry periods might explain spring germination. It is hypothesized that local adaptations occur through changes mainly in dormancy strength, i.e. how much effort that is needed to reduce dormancy; strong dormancy restrict the part of each seed batch that germinate during autumn, and thus risk winter mortality, in Sweden. Original publication: Laila M. Karlsson and Per Milberg, Variation within species and inter-species comparison of seed dormancy and germination of four annual Lamium species, 2008, Flora, (203), 5, 409-420. http://dx.doi.org/10.1016/j.flora.2007.08.001. Copyright: Elsevier B.V., http://www.elsevier.com/

Background and Aims: Comparative studies of closely related taxa can increase understanding of adaptations and changes in seed dormancy and germination preferences in an evolutionary perspective. For such studies, a method to describe and compare the performance of taxa in a general way is needed. The germination ecology of four Papaver taxa was studied with the aim of describing and comparing their responses to different seasonal temperature regimes. Methods: Germination of Papaver argemone, P. rhoeas, P. dubium ssp. dubium and P. dubium ssp. lecoqii was investigated in three different artificial climates over 2.5 years. Seeds were collected in southern Sweden, and samples from different populations were used as replicates of taxa. Key Results: Despite substantial intra-taxa variation, there were clear taxon-specific responses. Most germination occurred in the warmest climate. In general, the warmer the climate the more germination occurred in autumn instead of spring. Papaver argemone, phylogenetically most distant from the others, was, in contrast to the other taxa, restricted to germinating only at lower temperatures. Conclusions: Seed dormancy and germination may be described by dormancy pattern, germination preferences and dormancy strength. The general dormancy pattern was a common feature for these taxa and therefore probably an evolutionary conservative character. Germination preferences varied between taxa, resulting in different temperature optima and intervals for germination, and dormancy strength was to some extent taxon-specific, but highly variable. The dormancy pattern explained how the taxa can perform as winter annuals in warmer climates, but mainly as summer annuals in colder climates. Hence, there is no need to interpret the within-taxon temporal differences in seedling emergence as local adaptations. In the field, an entire seed cohort will not germinate during a single season. Instead, emergence will be distributed over several seasons, regardless of local climate, weather and soil cultivation methods. The original article is: Laila M. Karlsson and Per Milberg, A Comparative Study of Germination Ecology of Four Papaver Taxa, 2007, Annals of Botany, (99), 935-946. http://dx.doi.org/10.1093/aob/mcm045.