Phenological shifts enable species to adjust the timing of life-history events to required resources. Climate change alters the spatiotemporal association between temperature and photoperiod, modifying the scope for temperature regulation. Here, we propose a model hypothesizing that dissimilar light requirements and constraints differently impact phenological responses in diurnal versus nocturnal ectotherms. Next, we investigate temporal shifts and latitudinal trends in phenology for 363 Lepidoptera species using 44 years of citizen science data. In agreement with model predictions, long-term shifts in the estimated onset, peak, termination, and duration of the flight period differed qualitatively between diurnal and nocturnal species, even after accounting for voltinism and overwintering stage, supporting that diel activity is a key regulator of phenology. Phenology showed intraspecific latitudinal trends, and the peak occurred later in the north in diurnal species but was independent of latitude in nocturnal species. These contrasting phenological shifts may impact community composition and ecosystem functioning.

1. Movement is fundamental to population persistence and metapopulation dynamics, but robust comparative estimates of dispersal remain scarce for threatened butterflies. Limited quantitative data on movement constrain effective conservation network design.

2. We focused on three threatened butterfly species-Euphydryas aurinia, Parnassius apollo and Phengaris arion-co-occurring on Gotland, Sweden, which together provide an ideal model for comparative dispersal analysis.

3. To quantify and compare movement patterns among species using extended capture-mark-recapture (CMR) data, test for random-walk behaviour, and identify the best-fitting dispersal kernels.

4. CMR datasets for E. aurinia and P. apollo were extended to 2024 and combined with comprehensive data for P. arion, yielding 9670 net-displacement observations (the distance between the first and last captures) collected from 2017 to 2024. One movement value per individual was used to avoid pseudoreplication, detection probabilities were estimated with Cormack-Jolly-Seber models, and four dispersal kernels were evaluated.

5. Median net displacement differed significantly among species (chi(2) = 450.14, p < 0.001): E. aurinia showed the lowest value (0.135 km), while P. apollo (0.253 km) and P. arion (0.252 km) were similar. Movements deviated from random-walk expectations (log-log slope = 0.431 versus 0.5 expected, p < 0.001), indicating area-restricted movement. Lognormal kernels best described E. aurinia and P. apollo, whereas an exponential distribution fitted P. arion best, with maximum displacements of 8.19, 10.69 and 4.31 km, respectively.

6. Even butterflies traditionally regarded as sedentary exhibit substantial dispersal capacity. Species-specific movement strategies influence metapopulation connectivity, and the derived parameters provide essential inputs for designing habitat networks within each species's dispersal range.

Long-term ocean warming impacts the marine environment, and these effects will be exacerbated by future climate change affecting, e.g., biogeochemical processes and microbial communities. However, how the sediment microbial cell abundance and live/dead ratio respond to warming is poorly understood. In this study, sediment core samples were collected from a Baltic Sea bay artificially heated on average 5°C for > 50 years above a nearby (control) bay unaffected by the heating. Contrary to the expected increased productivity in the heated bay, qPCR-based sediment cell abundances showed decreased cell numbers along the sediment depth gradient in the heated bay compared to the control bay. This could reflect that a portion of the cells' metabolic energy was diverted to a heat related stress response rather than being used for replication. In addition, live/dead cell ratios showed no clear differences in either bay suggesting the majority of the cells were alive. Finally, sediment depth gradient 16S rRNA gene sequencing confirmed previous studies, showing that prolonged warming shallows sediment biogeochemical zones and related microbial communities. In conclusion, future climate change related warming will likely decrease microbial cell abundances that form part of the food web base, potentially impacting the entire ecosystem.

Global forest ecosystems are experiencing increasingly frequent and severe insect outbreaks, driven by complex interactions among climate change, land-use alterations, and shifting species distributions. Species that are morphologically indistinguishable - often referred to as cryptic species - can differ significantly in distribution, host use, and susceptibility to natural enemies and might thereby differ in outbreak dynamics. Yet, the contribution of cryptic species to temporal changes in the frequency and severity of insect outbreak dynamics remains poorly understood. Motivated by recent defoliation events in northern European oak forests, we investigated an emerging leaf-miner outbreak in Sweden. Through targeted surveys, rearing from 22 sites and Malaise trapping at 34 sites (56 sites total), we identified a pronounced spatial clustering of outbreaks at higher latitudes. The newly recognised cryptic species Acrocercops andreneli was strongly associated with these outbreaks, whereas sites with only Acrocercops brongniardella never showed outbreaks. Host-parasitoid networks related to the two cryptic moth species were strikingly similar. Our findings demonstrate the importance of cryptic species for outbreak dynamics and their consequences for host plant health in ways that are easily overlooked by traditional taxonomy. Moreover, such outbreak dynamics cannot always be linked to a lack of top-down control by natural enemies.

Theory, manipulation experiments and observational studies on biodiversity and ecosystem functioning largely concur that higher intraspecific diversity may increase the overall productivity of populations, buffer against environmental change and stabilize long-term productivity. However, evidence comes primarily from small and short-lived organisms. We tested for effects of genetic diversity on variation in forest growth by combining long-term data on annual individual growth rate (basal area increment (BAI)) with estimates of intrapopulation genetic variation (based on RAD-seq SNPs) for 18 natural Quercus robur pedunculate oak populations. Higher total or adaptive genetic variability of populations was neither associated with faster average growth nor with increased temporal or spatial stability of growth nor with among-individual asynchrony in growth. However, as expected, we found that greater asynchrony of growth responses within the populations increased their temporal stability. Together, these findings point towards a negligible role of genetic variation in structuring growth patterns in natural populations of tree species. Identifying which environmental factors and phenotypic traits (and its genetic basis) contribute to asynchronous growth responses is an important next step towards a better mechanistic understanding of the causes of temporal stability in tree growth and forest productivity.

The spatial synchrony framework suggests that asynchrony among subpopulations in different branches of a river network should stabilize the metapopulation. However, how barriers affect this framework remains poorly understood. This is a significant knowledge gap given that population synchrony arises from dispersal and environmental similarity, both of which are influenced by barriers. We empirically evaluated how barriers impact fish population synchrony and, subsequently, the associations between synchrony and metapopulation persistence, productivity, stability and trajectory within fragments. We found that barriers demographically decouple populations by decreasing synchrony in brown trout (Salmo trutta) and Eurasian minnow (Phoxinus phoxinus), but not in northern pike (Esox lucius), suggesting species-specific responses to fragmentation. Additionally, asynchrony had a stabilizing portfolio effect on metapopulation stability at the fragment level that was statistically significant for S. trutta. Higher fragment synchrony also made S. trutta and P. phoxinus populations less stable. The impact of barriers on riverine fish population synchrony emphasizes the need to include barriers in future studies on the causes and consequences of synchrony in rivers. That asynchrony stabilizes populations in some riverine fishes suggests that conservation priorities should lie in restoring or retaining larger fragment sizes and higher branching complexity with intact connectivity.

Introducing non-native tree species into forest ecosystems is a growing trend, in part as climate change may cause a decline of native species and shifts in species distributions. In European forestry, Quercus rubra (northern red oak) has increasingly been considered a candidate substitute species for native oaks. However, it remains largely unknown how this substitution affects associated biodiversity. This study compares the biodiversity supported by the native oak species Q. petraea (sessile oak) and Q. robur (pedunculate oak) and the invasive Q. rubra in southern Sweden, focusing on both oak-associated organisms and general forest biodiversity. Arthropods were sampled using Malaise traps at the site level. At the same time, vascular plants, leaf herbivory and endophytic insects (leaf miners and gallers) were recorded at the tree level in three sites per oak species. Our results reveal guild-specific effects of oak species on biodiversity. The introduced Q. rubra supported significantly fewer endophytic insects than native oak species. Vascular plant species richness was marginally lower in Q. petraea and Q. rubra sites compared to Q. robur. In contrast, the species richness, abundance, biomass and community composition of arthropods and leaf herbivory did not differ significantly between the three oak species. These findings indicate that the ecological consequences for biodiversity of introduced tree species, such as Q. rubra, are most pronounced for specialised herbivores, including leaf miners and gallers, and suggest that broader forest biodiversity measures may be less responsive to changes in tree species than to local environmental conditions.

Zooplankton are crucial for food webs and biogeochemical cycles. However, warming associated with climatechange may alter their seasonal timing and reproductive strategies. This study investigated how long-termwarming impacted zooplankton (mainly copepods) phenology and overwintering strategies by comparing a Bal-tic Sea bay, heated by warm water discharge for more than 50 yr, with an unaffected control bay. Field observa-tions showed that copepod and phytoplankton population growth began earlier in the heated bay than in thecontrol bay, suggesting that copepod abundance was driven by both temperature and food availability in theheated bay and by a stronger temperature dependence in the control bay. Resting eggs are normally producedas a life-history strategy to survive unfavorable environmental conditions. Our laboratory incubation experi-ment showed fewer dormant resting eggs hatched from the heated bay sediment compared with the controlbay, supporting an evolutionary change in overwintering strategy. In conclusion, the results seemed to suggestthat copepods adjusted their life-history in elevated temperatures by relying less on the strategy of usingsediment-stored dormant eggs and instead started their spring development earlier, when phytoplankton foodwas available. Hence, this study suggests that climate change can shift copepod overwintering strategies, leadingto potential cascading effects in the food web and affecting overall biodiversity and productivity.

This study evaluates five sampling methods for characterising saproxylic beetle assemblages in a recently burned (18-21 June 2021) boreal forest in southeastern Sweden. We compared species richness and community composition in samples collected using trunk traps, flight-intercept traps, pheromone traps, Malaise traps, and manual searches, deployed in the Finsjöbrännan nature reserve between 2022 and 2024. A total of 2258 beetle specimens were collected, representing 559 species, including 36 red-listed taxa. Flight-intercept traps yielded the highest species richness (331 species) and abundance, while trunk traps were most effective at detecting red-listed species (13.4% of species captured by trunk traps were red-listed). Coverage-based rarefaction indicated that deploying trunk and flight-intercept traps together could detect approximately 89% of the beetle species (by extrapolated richness); however, this two-method combination necessarily spans different succession stages. Notably, 61.1% of the red-listed species were captured exclusively by a single trap type, underscoring the complementary nature of different sampling approaches. Although non-overlapping sampling years may have confounded the comparisons between trap types, these results suggested that methodological choices, combined with temporal factors, may strongly influence biodiversity assessments in post-fire habitats. We provide evidence-based recommendations for effective sampling protocols, emphasising the need for multi-method approaches and temporal consistency in conservation-focused monitoring. Implications for insect conservation: Post-fire forests represent critical habitats for numerous saproxylic beetles, including many species of conservation concern that depend on recently burned wood. Our results demonstrate that no single sampling method adequately captures the full diversity of post-fire beetle assemblages, as red-listed species often occur exclusively in one type of trap. Therefore, conservation monitoring and biodiversity inventories in burned forests should employ a combination of complementary methods-particularly flight-intercept and trunk traps-to maximise species detection. Standardising temporal deployment and ensuring sampling continuity across years are essential for reliable comparisons among fires and regions. Incorporating such multi-method protocols into long-term monitoring will strengthen assessments of post-disturbance recovery and support evidence-based management of fire-dependent insect communities.

Leaf phenology of trees responds to temperature and photoperiod cues, mediated by underlying genes and plasticity. However, uncertainties remain regarding how smaller-scale phenological variation in cold-limited regions has been affected by modified selection pressures from herbivores, pathogens, and climate conditions, and whether this leaves genetic signatures allowing for projections of future responses. We investigated environmental correlates and genetic variation putatively associated with spring and autumn leaf phenology in northern range margin oak (Quercus robur L.) populations in Sweden (55.6 degrees N-60.8 degrees N). Results suggested that budburst occurred later at higher latitudes and in locations with colder spring (April) temperatures, whereas leaf senescence occurred earlier at higher latitudes. Several candidate loci associated with phenology were identified (n = 40 for budburst and 47 for leaf senescence), and significant associations between these loci and latitude were detected. Functions associated with some of the candidate loci, as identified in previous studies, included host defence and heat stress tolerance. The proportion of polymorphic candidate loci associated with budburst decreased with increasing latitude, towards the range margin. Overall, the Swedish oak population seems to comprise genetic diversity in phenology-related traits that may provide resilience to a rapidly changing climate.