The tree species matters: Biodiversity and ecosystem service implications of replacing Scots pine production stands with Norway spruce

Ambio - The choice of tree species used in production forests matters for biodiversity and ecosystem services. In Sweden, damage to young production forests by large browsing herbivores is helping...     

Correction to: Keeping pace with forestry: Multi-scale conservation in a changing production forest matrix

Ambio - In the original published article, the sentence “Nevertheless, semi-natural forest remnants continue to be harvested and fragmented (Svensson et al. 2018; Jonsson et al. 2019), and...     

The effect of an active steering system on city bus drivers’ muscle activity

City bus drivers spend hours driving under time pressure, in congested traffic and in a monotonous sitting position. This leads to unhealthy working conditions, especially in terms of physical and psychological stress. The aim of this study is to investigate whether an active steering system can alleviate the musculoskeletal stress involved in manoeuvring a bus. Twenty bus drivers drove a city bus equipped with the Volvo dynamic steering (VDS) support system in real traffic. Steering effort was evaluated with electromyography and with a questionnaire. Compared to baseline, VDS significantly reduced the required muscle activity by on average 15–25% while turning, and up to 68% in the part of the manoeuvre requiring maximum effort. The bus drivers believed that VDS will help reduce neck and shoulder problems, and they expressed a desire to have VDS installed in their own bus.     

Effects of Population Size and Food Stress on Fitness-Related Characters in the Scarce Heath, a Rare Butterfly in Western Europe

Abstract: Knowledge about the effects of inbreeding in natural populations is scarce, especially in invertebrates. We analyzed to what extent fitness-related traits in the scarce heath (  Coenonympha hero ), a butterfly, are affected by population size and isolation and whether differences in food quality influence these effects. We categorized nine populations as either large or small and isolated. Full-sib groups of offspring from 27 females were followed under seminatural conditions. Because of increased zygote mortality, egg hatchability was significantly lower in the small and isolated populations than in the large ones. Population category had no effect on larval weight under optimal conditions, but weight was significantly lower in the small-isolated category with low food quality. The effects of inbreeding can thus be hidden when conditions are benign but can appear under stress. Survival also differed significantly between population categories, and larval developmental time tended to be longer in the small-isolated category, irrespective of food conditions. We suggest that the differences in fitness between offspring from large and small isolated populations are at least partly due to inbreeding. This adds a further threat to a species that is already suffering from decreasing population sizes and increasing isolation among populations.     

Seasonal polyphenism in life history traits: time costs of direct development in a butterfly

Insects with two or more generations per year will generally experience different selection regimes depending on the season, and accordingly show seasonal polyphenisms. In butterflies, seasonal polyphenism has been shown with respect to morphology, life history characteristics and behaviour. In temperate bivoltine species, the directly developing generation is more time-constrained than the diapause generation, and this may affect various life history traits such as mating propensity (time from eclosion to mating). Here, we test whether mating propensity differs between generations in Pieris napi, along with several physiological parameters, i.e. male sex pheromone synthesis, and female ovigeny index and fecundity. As predicted, individuals of the directly developing generation—who have shorter time for pupal development—are more immature at eclosion; males take longer to synthesise the male sex pheromone after eclosion and take longer to mate than diapause generation males. Females show the same physiological pattern; the directly developing females lay fewer eggs than diapausing females during the first days of their life. Nevertheless, the directly developing females mate faster after eclosion than diapausing females, indicating substantial adult time stress in this generation and possibly an adaptive value of shortening the pre-reproductive period. Our study highlights how time stress can be predictably different between generations, affecting both life history and behaviour. By analysing several life history traits simultaneously, we adopt a multi-trait approach to examining how adaptations and developmental constraints likely interplay to shape these seasonal polyphenisms.     

Female mate choice determines reproductive isolation between sympatric butterflies

Animal courtship rituals are important for species recognition, and a variety of cues might be utilized to recognize conspecific mates. In this paper, we investigate different species-recognition mechanisms between two sympatric butterfly sister species: the wood white (Leptidea sinapis) and Real’s wood white (Leptidea reali). We show that males of both species frequently court heterospecific females both under laboratory and field conditions. The long-lasting elaborate courtships impose energetic costs, since the second courtship of males that were introduced to two subsequent conspecific females lasted on average only one fourth as long as the first courtship. In this paper, we demonstrate that premating reproductive isolation is dependent on female unwillingness to accept heterospecific mates. We studied female and male courtship behavior, chemical signaling, and the morphology of the sexually dimorphic antennae, one of the few male traits visible for females during courtship. We found no differences in ultraviolet (UV) reflectance and only small differences in longer wavelengths and brightness, significant between-species differences, but strongly overlapping distributions of male L. sinapis and L. reali antennal morphology and chemical signals and minor differences in courtship behavior. The lack of clear-cut between-species differences further explains the lack of male species recognition, and the overall similarity might have caused the long-lasting elaborate courtships, if females need prolonged male courtships to distinguish between con- and heterospecific suitors.     

Rodent predation on hibernating peacock and small tortoiseshell butterflies

Insects that hibernate as adults have a life span of almost a whole year. Hence, they must have extraordinary adaptations for adult survival. In this paper, we study winter survival in two butterflies that hibernate as adults and have multimodal anti-predator defences—the peacock, Inachis io, which has intimidating eyespots that are effective against bird predation, and the small tortoiseshell, Aglais urticae, which does not have an effective secondary defence against birds. We assessed predation on wild butterflies hibernating in the attic of an unheated house, as well as survival of individually marked butterflies placed by hand on different sites in the attic. Our objectives were to assess (1) the number of butterflies that were killed during hibernation, (2) whether survival differed between butterfly species, and (3) how predation was related to hibernation site and the identity of the predator. There was a strong pulse of predation during the first 2 weeks of hibernation: 58% of A. urticae and 53% of I. io were killed during this period. Thereafter, predation decreased and butterfly survival equalled 98% during the final 16 weeks of hibernation. There was no difference in survival between the two butterfly species, but predation was site-specific and more pronounced under light conditions in locations accessible to a climbing rodent, such as the common yellow-necked mouse, Apodemus flavicollis. We contend that small rodents are likely important predators on overwintering butterflies, both because rodents are active throughout winter when butterflies are torpid and because they occur at similar sites.     

Spatial cost efficiency in waste paper handling: the case of corrugated board in Sweden

This paper analyzes the spatial cost efficiency of the Swedish legislation regarding waste disposal handling. We focus on the case of corrugated board and recognize that the different counties in Sweden possess different economic prerequisites in terms of waste paper recovery and utilization potential. We employ data for six corrugated board mills and 20 counties and a non-linear programming model to identify the least cost strategy for reaching the politically specified recycling target of a 65% recovery rate for corrugated board. That is, the total costs of recovering a minimum of 65% in each county are calculated and compared with the case when the country as a whole recovers 65% of all old corrugated board is collected but there exist no uniform target for each county. The conclusion is that from an efficiency point of view the recovery efforts should be concentrated to the highly populated and urbanized counties, and not be uniformly divided throughout the country. In the base case, the results suggest that the cost efficient county-specific recovery rates should range from 51 to 72%.     

Contrasting Landscape Influences on Sediment Supply and Stream Restoration Priorities in Northern Fennoscandia (Sweden and Finland) and Coastal British Columbia

Sediment size and supply exert a dominant control on channel structure. We review the role of sediment supply in channel structure, and how regional differences in sediment supply and landuse affect stream restoration priorities. We show how stream restoration goals are best understood within a common fluvial geomorphology framework defined by sediment supply, storage, and transport. Landuse impacts in geologically young landscapes with high sediment yields (e.g., coastal British Columbia) typically result in loss of instream wood and accelerated sediment inputs from bank erosion, logging roads, hillslopes and gullies. In contrast, northern Sweden and Finland are landscapes with naturally low sediment yields caused by low relief, resistant bedrock, and abundant mainstem lakes that act as sediment traps. Landuse impacts involved extensive channel narrowing, removal of obstructions, and bank armouring with boulders to facilitate timber floating, thereby reducing sediment supply from bank erosion while increasing export through higher channel velocities. These contrasting landuse impacts have pushed stream channels in opposite directions (aggradation versus degradation) within a phase-space defined by sediment transport and supply. Restoration in coastal British Columbia has focused on reducing sediment supply (through bank and hillslope stabilization) and restoring wood inputs. In contrast, restoration in northern Fennoscandia (Sweden and Finland) has focused on channel widening and removal of bank-armouring boulders to increase sediment supply and retention. These contrasting restoration priorities illustrate the consequences of divergent regional landuse impacts on sediment supply, and the utility of planning restoration activities within a mechanistic sediment supply-transport framework.