Monitoring pollinator populations is crucial for understanding biodiversity trends and ensuring the health of ecosystems, especially in agricultural landscapes. This study introduces the "Knautia Pollinator Walk" as a new method for tracking pollinator diversity and abundance. By observing pollinators visiting the inflorescence of Knautia arvensis, we found significant correlations between pollinators and land use, and there were significant differences in pollinator communities between regions. Our findings highlight the importance of habitat type in influencing pollinator populations, offering a valuable tool for conservation efforts. Declining populations of native pollinators, especially wild bees, underline the urgent need for effective monitoring within agricultural ecosystems. This study aims to (i) establish the 'Knautia Pollinator Walk' as an innovative pollinator monitoring method, (ii) examine the link between pollinator richness/density and land cover, and (iii) assess if specialist solitary bees indicate pollinator abundance and morphogroup richness. The approach involves surveying 500 Knautia arvensis inflorescences per site thrice per season. Observations of 11,567 pollinators across 203 taxa showed significant correlations between pollinator diversity and land use. Pollinator populations fluctuated with land cover type, increasing in open areas but decreasing or stabilising in forested and shrubby regions. Noteworthy differences in pollinator types were seen between Russia (solitary bees, small Diptera, Lepidoptera) and Sweden (bumblebees, beetles, furry Diptera). The "Knautia Pollinator Walk" shows promising signs of being an effective tool for monitoring spatiotemporal biodiversity trends. The method offers a scalable approach to pollinator monitoring, which is essential for developing conservation strategies and supporting pollinator populations.

Colour polymorphisms have long served as model systems in evolutionary studies and continue to inform about processes involved in the origin and dynamics of biodiversity. Modern sequencing tools allow for evaluating whether phenotypic differences between morphs reflect genetic differentiation rather than developmental plasticity, and for investigating whether polymorphisms represent intermediate stages of diversification towards speciation. We investigated phenotypic and genetic differentiation between two colour morphs of the butterfly Fabriciana adippe using a combination of ddRAD-sequencing and comparisons of body size, colour patterns and optical properties of bright wing spots. The silvery-spotted adippe form had larger and darker wings and reflected UV light, while the yellow cleodoxa form displayed more green scales and reflected very little UV, showcasing that they constitute distinct and alternative integrated phenotypes. Genomic analyses revealed genetic structuring according to source population, and to colour morph, suggesting that the phenotypic differentiation reflects evolutionary modifications. We report 17 outlier loci associated with colour morph, including ultraviolet-sensitive visual pigment (UVRh1), which is associated with intraspecific communication and mate choice in butterflies. Together with the demonstration that the wings of the adippe (but essentially not the cleodoxa) morph reflect UV light, that UV reflectance is higher in females than males and that morphs differ in wing size, this suggests that these colour morphs might represent genetically integrated phenotypes, possibly adapted to different microhabitats. We propose that non-random mating might contribute to the differentiation and maintenance of the polymorphism.

Context Conservation of endangered species necessitates an in-depth understanding of their ecological requirements. Particularly in landscape ecology, the behavioural tendencies of threatened butterfly species in Gotland, a biodiversity-rich island in the Baltic Sea, become crucial.

Objectives The primary aim of this study was to elucidate the movement patterns of three threatened butterfly species-Euphydryas aurinia, Parnassius apollo, and Phengaris arion-in Gotland and to identify the influence of specific land characteristics on these patterns.

Methods Our study, conducted from 2017 to 2020 across 60 km2 in Gotland, involved detailed capture-mark-recapture (CMR) efforts of 29,584 captures including 16,223 unique butterflies. We investigate the departure and arrival events of butterflies, specifically focusing on the associations between movements when individuals leave or enter a hectare grid different from their previously recorded location and key landscape features: open vegetated land, ground moisture, and forest cover. We model landscape features to examine the interplay between these and butterfly movement patterns, providing insights into preferred landscape features and conservation strategies.

Results Among the 4821 arrivals and 5083 departures documented, the species exhibited differential responses to the evaluated habitat features. Both E. aurinia and P. apollo displayed a positive density-dependent dispersal, while P. arion's movements were not significantly associated with any of the examined habitat features. Landscape properties like open vegetated land and ground moisture index statistically influenced the likelihood of arrival and departure.

Conclusions The study accentuates the relationship between land cover and the behavioural tendencies of the subject butterfly species. It has broader implications for the targeted habitat management strategies that would benefit threatened butterfly populations in Gotland.

Adaptive governance of areas set aside for future protection of biodiversity, sustainable production, and recreation requires knowledge about whether and how effects of area protection are modulated by climate change and redistribution of species. To investigate this, we compare biodiversity of plants (assessed using vegetation plots) and arthropods (collected with Malaise traps, analyzed using metabarcoding) and productivity (tree growth, determined using dendrochronology) in protected and non-protected oak ( Quercus spp.) forests along a latitudinal gradient (55.6 degrees N- 60.8 degrees N) in Sweden. We also compare historical, recent and projected future climate in the region. In contrast to established global latitudinal diversity gradients, species richness of plants and arthropods increased northwards, possibly reflecting recent climate-induced community redistributions, but neither was higher in protected than in non-protected areas, nor associated with contemporary ground temperature. Species composition of arthropods also did not differ between protected and non-protected areas. Arthropod biomass increased with latitude, suggesting that the magnitude of cascading effects mediated via their roles as pollinators, herbivores, and prey for other trophic levels, varies geographically and will change with a moving climate. Annual growth rate of oaks (an ecosystem service in the form of biomass increase and carbon sequestration) was independent of latitude and did not differ between protected and non-protected areas. Our findings question the efficacy of contemporary designation and management of protected oak forests, and emphasize that development and implementation of modified climate smart conservation strategies is needed to safeguard ecosystem functioning, biodiversity, and recreational values of protected forest areas against future challenges.

The dynamic interplay between anthropogenic activities and biodiversity conservation necessitates a nuanced understanding of habitat change, especially in contexts marked by transitions from grasslands to forested areas. This investigation utilised three threatened butterfly species-the Marsh Fritillary, Apollo, and Large Blue-as models to explore how grassland associated species respond to altered environmental conditions. The methodology encompassed extensive field surveys and statistical analyses with ecological niche modelling to determine their current and future distributions on the Island of Gotland. The species were surveyed under distinct years from 2017 to 2020 in a total of 3333 hectares in a 6000 hectare area-the Marsh Fritillary in 2017 (1232 hectares), Apollo in 2019 (2346 hectares), and Large Blue in 2020 (2256 hectares). Results revealed that the estimated current extents of suitable habitats were 49,104 hectares for the Marsh Fritillary (15.6% of the island), 45,646 hectares for Apollo (14.5%), and 33,089 hectares for Large Blue (10.5%). In general, increased forest and shrub cover and decreased heterogeneity negatively affected butterfly occupancy, but each species exhibited unique habitat preferences. The predictive modelling demonstrated that continued succession would reduce the amount of habitats predicted to be suitable and generated alarming forecasts-a twofold increase in forest and shrub cover suggests habitat declines of 41%, 47%, and 65% for the Marsh Fritillary, Apollo, and Large Blue, respectively. Given these findings, proactive measures are imperative for strategically managing these habitats to preserve landscape heterogeneity and accommodate diverse ecological needs. This study is important to conservation management providing, crucial insights amid anthropogenic and ecological changes.

1. Established butterfly survey methods that are useful for monitoring species that are widely distributed and numerous may be less accurate for more rare species. We therefore need new monitoring approaches.2. We describe a plot-based survey method, where butterflies or larvae nests are counted within 1-ha grid cells. The aim was to compare this grid method with more traditional transect counts and evaluate both methods in relation to high-quality capture-mark-release (CMR) population estimates (reflecting the 'true' population). We do this using data from a large population of the marsh fritillary butterfly in Sweden. Moreover, we followed the overall population trend from 2017 to 2021 for both adult butterflies and larvae.3. Results showed a higher detection probability using the grid method compared with transect counts, which for adult butterflies seem to be explained by time effort. Moreover, grid surveys of adult butterflies showed a clear significant relationship with the estimated 'true' population size from CMR, while transect counts did not. For larvae, both methods showed significant relationships with the estimated adult population size, but the grid method found 5.7 times more larvae. The overall popu-lation fluctuated significantly across years. In years with low densities, the transect method largely failed to detect the species.4. The grid method seems more reliable for detecting the marsh fritillary and for estimating its population size, and thus, tracking the population trend. We propose this novel method to be integrated into surveys and monitoring of biodiversity, especially when focusing on rare habitat specialists that are normally underrepre-sented in monitoring based on volunteer counts.

Species-rich semi-natural grasslands have been lost during the last century due to agricultural intensification. This has had large negative consequences for many specialised species, including grassland butterflies. To prevent further loss, management regimes in the remaining grasslands must maintain habitat quality over time, and we therefore need to understand the habitat preferences of specialised species and how different management regimes affect their survival. We studied the egg-laying preferences of the threatened marsh fritillary butterfly in relation to host plant properties, microclimate and management (grazing) on Gotland, Sweden. Moreover, we followed the survival of eggs and larvae from 27 egg batches during a period of 8 months (from June 2020 to March 2021) in grazed and ungrazed areas. We found 92 egg batches in total and the average number of eggs was 184.5. Egg-laying probability increased with increasing host plant size and abundance, and environmental variables associated with a warm microclimate (low grass cover, low vegetation height and south-facing edges). The 27 egg batches that were followed over time had on average 203 eggs in June. Roughly 28% of the eggs developed into larvae, and about 17% of these survived over the entire study period, resulting in an overall 4.7% survival. Egg survival was higher in ungrazed habitats compared with grazed; in March (post-hibernation), there were almost nine times more eggs in ungrazed habitats. This study highlights the complex habitat ecology of specialised butterflies and underscores the detrimental impact of intense grazing, advocating for rotational grazing or mowing regimes. We study oviposition preferences and survival of both eggs and larvae (post-hibernation) for the marsh fritillary, in relation to host plant availability, microclimate conditions and grazing management Egg-laying probability increased with increasing host plant size and abundance, and environmental variables associated with a warm microclimate (low grass cover, low vegetation height and south-facing edges) Egg survival was clearly higher in ungrazed habitats compared with grazed; in March (post-hibernation), there were almost nine times more eggs in ungrazed habitats. image

For two decades, DNA barcoding and, more recently, DNA metabarcoding have been used for molecular species identification and estimating biodiversity. Despite their growing use, few studies have systematically evaluated these methods. This study aims to evaluate the efficacy of barcoding methods in identifying species and estimating biodiversity, by assessing their consistency with traditional morphological identification and evaluating how assignment consistency is influenced by taxonomic group, sequence similarity thresholds and geographic distance. We first analysed 951 insect specimens across three taxonomic groups: butterflies, bumblebees and parasitic wasps, using both morphological taxonomy and single-specimen COI DNA barcoding. An additional 25,047 butterfly specimens were identified by COI DNA metabarcoding. Finally, we performed a systematic review of 99 studies to assess average consistency between insect species identity assigned via morphology and COI barcoding and to examine the distribution of research effort. Species assignment consistency was influenced by taxonomic group, sequence similarity thresholds and geographic distance. An average assignment consistency of 49% was found across taxonomic groups, with parasitic wasps displaying lower consistency due to taxonomic impediment. The number of missing matches doubled with a 100% sequence similarity threshold and COI intraspecific variation increased with geographic distance. Metabarcoding results aligned well with morphological biodiversity estimates and a strong positive correlation between sequence reads and species abundance was found. The systematic review revealed an 89% average consistency and also indicated taxonomic and geographic biases in research effort. Together, our findings demonstrate that while problems persist, barcoding approaches offer robust alternatives to traditional taxonomy for biodiversity assessment.

Oak species worldwide face substantial challenges in natural recruitment, significantly affecting biodiversity and ecosystem services. Oaks are a keystone species in northern temperate zones, influencing ecosystem dynamics. This study analysed oak regeneration patterns from 29 oak stands ( Quercus spp.) across southern Sweden up to the species ' northern range limit. The study focused on two native species, Q. robur and Q. petraea , and one introduced species, Q. rubra , used in Swedish forestry. We aimed to evaluate whether and how oak regeneration was i) associated with latitude, ii) influenced by ground moisture and nitrogen levels, and iii) correlated with stand age, as well as to iv) compare regeneration rates among the species. Contrary to the hypothesis that oak regeneration should decline towards the range margin, our results did not indicate any latitudinal association. This finding raises the possibility of a future northward range expansion for oaks. We also observed that oak regeneration was positively correlated with stand age, while increasing nitrogen and ground moisture levels were inversely related to regeneration. The positive age-dependent effect on recruitment also indicates that species recruitment dynamics within forests may be modified via age-dependent effects within the tree community, with implications for forestry and conservation management. Notably, the natural regeneration of the introduced Q. rubra indicates its successful adaptation to Swedish climate and forests. This study represents Sweden 's first large-scale analysis of oak regeneration across multiple oak species. Future research should prioritise longitudinal monitoring, particularly at the northern range limits, and further investigate the expansion of the potentially invasive Q. rubra .

Forests are pivotal for biodiversity, food webs, and human economies, and as carbon sinks their climate change mitigation potential is undisputed. However, whether trees continue to efficiently accumulate biomass at an increasing rate with age, how growth trajectories respond to climate change, and vary with latitude at species range margins is under debate. Here, we combine tree-ring data with biometric equation modeling to analyze how annual biomass increment varies according to tree age, species, latitude, and germination year. We generated 26,225 estimates of annual biomass increments for 136 individual trees, representing two evergreen gymnosperm conifer species ( Picea abies (L.) H.Karst., and Pinus sylvestris L.) and two deciduous angiosperm species ( Quercus spp. L. and Fagus sylvatica L.). Our dataset includes some old trees (range 150- 405 years), and samples from locations spanning >10 degrees latitude (55.0- 66.3 degrees N) in Sweden. Annual biomass increments varied considerably between species, years and among individual trees within stands. On average, biomass increment remained positive throughout the lifespan across trees, species, and latitudes. Age-specific biomass increment was higher in the deciduous than in the evergreen species and declined with increasing latitude within species. For spruce and beech, biomass increment increased significantly with germination year, possibly reflecting faster growth in recent times in response to a warmer climate. The findings have implications for forestry practices aimed at productivity, biodiversity conservation, and climate change mitigation.