Victor Johansson

• PhD
• Researcher at Linköping University

Butterfly populations in Europe are declining, necessitating efficient conservation strategies. Understanding butterfly behaviour in relation to habitat quality is important, and one aspect is flight behaviour at habitat edges. This study investigates flight patterns of the marsh fritillary (Euphydryas aurinia) in relation to edges between intensiv...

Simple Summary How far in space and time should conservation burns be conducted to provide most benefit to beetles favoured by forest fires? We systematically sampled forest reserves with different fire history and found that most pyrophilic beetles were found when fires in the vicinity of the reserves were close and quite recent. Abstract The num...

Boreal forests undergo rapid transformation from more or less intact states to even-aged production stands, due to the expanding clearcutting practice. Deepened knowledge on how species diversity and composition vary with local resource availability, such as dead wood, as well with remaining never clearcut forest (having long continuity = ‘continui...

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 mov...

This study investigates the ecology of three threatened butterfly species on a 60 km ² site in Gotland, Southeast Sweden, using mark–recapture methods from 2017 to 2020. Nearly 30,000 captures were recorded, with average lifespans of 6 days for Euphydryas aurinia (Lepidoptera: Nymphalidae) and Parnassius apollo (Lepidoptera: Papilionidae) and 2 day...

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...

The extent to which weeds in arable land are useful to pollinators depends in part on the temporal pattern of flowering and insect flight activity. We compiled citizen science data on 54 bees and hoverflies typical of agricultural areas in southern Sweden, as well as 24 flowering weed species classified as pollinator‐friendly in the sense that they...

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 nee...

When restoring habitats, an important question is whether the spatial distribution of habitat affects its contribution to biodiversity conservation. In Sweden, high-cut stumps are routinely created at forestry operations. By counting the number of exit holes of a red-listed beetle, Peltis grossa, we assessed occurrence, colonisations and extinction...

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. 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 m...

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 mo...

It remains unclear to what extent yearly weather variation and spatial variation in microclimate influences the outcome of interacting plant-animal species and whether responses differ between life stages. We collected data over several years on 46 ha on File Hajdar, Gotland, Sweden, and executed a complete mapping of larva nests (n = 776) and imag...

We used observational data collected during a mark-recapture study that generated a total of 7503 captures of 6108 unique individuals representing three endangered butterfly species to quantify inter-and intraindividual variation in temperature utilization and examine how activity patterns vary according to season, time of day, and ambient temperat...

When restoring habitats, an important question is whether the spatial distribution of habitat affects its contribution to biodiversity conservation. In Sweden, high-cut stumps are routinely created at forestry operations. By counting the number of exit holes of a red-listed beetle, Peltis grossa , we assessed occurrence, colonisations and extinctio...

In Europe, Natura 2000 sites should protect threatened target species and networks of habitats. The management of Natura 2000 grasslands is often financed by subsidized grazing as part of the Common Agricultural Policy (CAP). We studied the extent of CAP grazing for Natura 2000 management and how this affects a butterfly target species (the marsh f...

Extreme weather events are becoming more frequent due to climate change. We therefore need to understand how species respond to these events. In 2018, the worst drought ever recorded hit the island of Gotland in the Baltic Sea, which led to a major decline of the threatened marsh fritillary ( Euphydryas aurinia ) the succeeding summer. We compared...

Increased frequency and new types of disturbances caused by global change calls for deepened insights into possible alterations of successional pathways. Despite current interest in disturbance interactions there is a striking lack of studies focusing on the implication of decreasing times between disturbances. We surveyed forest‐floor vegetation (...

Questions Do burn severity and soil chemistry drive species and trait composition on recently burned clear‐cuttings? Does the spatial distribution of common, easily dispersed colonizers vary with distance to fire perimeter? Location A 13,000 ha production forest landscape in boreal southern Sweden burned in a wildfire in 2014. Methods Vascular pl...

Insect pollinators are declining, which often is related to intensified agriculture. Less focus has been on the effect of forestry. In many boreal forests, clear-cutting has replaced fire as the main disturbance agent, which has been negative for many species. Therefore, prescribed burning is performed, often on clear-cuts. Knowledge on the effect...

Extreme weather events can be expected to increase in frequency in the future. Our knowledge on how this may affect species persistence is, however, very limited. For reliable projections of future persistence we need to understand how extreme weather affects species' population dynamics. We analysed the effect of extreme droughts on the host plant...

Grazing generally benefits grassland biodiversity as it prevents shrub and tree succession. However, too intense grazing may have negative effects for example many grassland insects. EU-subsidies for grazing of some habitats, aimed at promoting biodiversity, still require a relatively intense grazing, and could therefore have negative consequences...

Protected areas are a key component in biodiversity conservation strategies, but evaluations of how effective they are in capturing species diversity is lacking for many ecosystems. We compared different protection types (animal sanctuaries, nature reserves and unprotected areas) using data on species richness and occurrence of coastal breeding bir...

Dispersal is a fundamental biological process that can be divided into three phases: release, transportation, and deposition. Determining the mechanisms of diaspore release is of prime importance to understand under which climatic conditions and at which frequency diaspores are released and transported. In mosses, wherein spore dispersal takes plac...

Abstract. Maintaining biodiversity in urban landscapes requires a well-functioning green infrastructure for the landscape to remain ecologically functional. However, city planners often lack knowledge to iden- tify how well different parts of the green infrastructure are connected, and tools to estimate the accessibility to important habitats for d...

Question Many species‐rich communities are associated with a foundation species. While we often have detailed information about the foundation species, we know less about its associated species. We explore such a situation, comparing the responses of lichen species associated with different tree taxa, which differ in successional strategy, to the e...

Tree retention on clear-cuts is a relatively new measure in forestry aimed at ‘lifeboating’ forest species during young seral periods. However, the effectiveness of tree retention for maintaining biodiversity for more than a few years is still poorly known. We investigated lichen persistence in retained buffer strips along small streams after clear...

Stumps and slash resulting from forest clearcutting is used as a source of low-net-carbon energy, but there are concerns about the consequences of biofuel extraction on biodiversity. Logging residues constitute potentially important habitats, since a large part of forest biodiversity is dependent on dead wood. Here we used snapshot field data from...

Roads may act as barriers to animal movements, but direct barrier effects on insects have rarely been studied. In this study we collected data on bees and wasps along two sides of a large road in Sweden using yellow pan traps. We then analyzed if the species composition differed between the two sides of the road; first for the whole community, and...

To replace fossil fuel and thereby mitigate climate change, harvesting of wood such as stumps for bioenergy will likely increase. Coarse deadwood is an important resource for biodiversity and stumps comprise the main part of the coarse deadwood in managed forests. We provide the first integrated analysis of the long-term climate and biodiversity im...

Understanding the complete dispersal process is important for making realistic predictions of species distributions, but mechanisms for diaspore release in wind‐dispersed species are often unknown. However, diaspore release under conditions that increase the probability of longer dispersal distances and mechanisms that extend dispersal events in ti...

Green tree retention is often applied in forests otherwise harvested by clearcutting. Its aim is to support biodiversity by contributing to a continuity of living trees and large-diameter dead wood in the new generation of a forest. However, high levels of mortality can undermine the aims of tree retention and pose a concern for forest managers. Th...

For efficient conservation, we need to consider both what kinds of habitat species require and the landscape-level supply of these habitats. We examined the relative importance of stand and dead wood types for wood-dependent lichens in two managed boreal forest landscapes in Sweden. We found 20 species and modelled their abundance based on stand ty...

Forest pest insects may cause large-scale tree growth reductions and tree mortality during outbreaks. The large-scale development of outbreaks has frequently been studied, while the colonization-extinction dynamics during outbreaks is less known. We study the colonization-extinction dynamics of a severe tree-killing bark beetle, Ips typographus, du...

Dead wood is an important resource for biodiversity, which has often decreased due to forest management. There is an increasing interest in extracting woody residues on clear-cuts for bioenergy production, which will further decrease dead wood amounts. Empirical studies show that such extraction decreases habitat availability for many species at a...

Wind is the main dispersal agent for a wide array of species and for these species the environmental conditions under which diaspores are released can potentially modify the dispersal kernel substantially. Little is known about how bryophytes regulate spore release, but conditions affecting peristome movements and vibration of the seta may be impor...

Context Species distributions are influenced by habitat conditions and ecological processes at multiple spatial scales. An understanding of the importance of habitat characteristics at different spatial scales is important when developing biodiversity conservation measures. Objectives We investigated the effect of habitat characteristics or amount...

Adequately describing the dispersal mechanisms of a species is important for understanding and predicting its distribution dynamics in space and time. For wind‐dispersed species, the transportation of airborne propagules is comparatively well studied, while the mechanisms triggering propagule release are poorly understood, especially for cryptogams...

Population fluctuations and synchrony influence population persistence; species with larger fluctuations and more synchronised population fluctuations face higher extinction risks. Here, we analyse the effect of diet specialisation, mobility, length of the flight period, and distance to the northern edge of the species' distribution in relation to...

Old trees have declined in E urope due to agricultural intensification and forestry. For shade‐intolerant epiphytic species occurring on old trees in semi‐open landscapes, host tree numbers have further decreased because of shading by developing secondary woodland. Moreover, in this habitat, regeneration that could replace the extant old trees is l...

G amla träd utgör en viktig livsmiljö för många organismer, men har minskat kraftigt i det moderna skogs-och jordbrukslandskapet (Kirby m.fl. 1995, Nilsson 1997). I södra Sverige återfinns riktigt gamla träd främst i hagmarker och andra kvarvarande rester av gamla odlingslandskap. Skötseln av dessa är därför mycket viktig för den långsiktiga överle...

Habitat loss is a major cause of species decline and extinction. Immediately after habitat loss, species occurrences are not in equilibrium with the new landscape and more closely reflect the previous landscape structure. Species with slow colonisation-extinction dynamics may display long time-lags before reaching a new equilibrium. We investigated...

The colonization-extinction dynamics of many species are affected by the dynamics of their patches. For increasing our understanding of the metapopulation dynamics of sessile species confined to dynamic patches, we fitted a Bayesian incidence function model extended for dynamic landscapes to snapshot data on five epiphytic lichens among 2083 mapped...

We modelled presence/absence per tree of beetles and pseudoscorpions living in tree hollows in relation to trunk circumference, habitat openness, and connectivity (=density of hollow oaks in the surrounding area), using data from 281 oaks. The presence/absence models were then used to predict species’ occurrences in a county (11,600km2) in southeas...

This study aimed at comparing six patch connectivity measures by fitting them to field data. We used occupancy data for eight beetle and two pseudoscorpion species from 281 hollow oaks in southeast Sweden. Species occupancy was modelled in relation to tree characteristics and one measure of patch connectivity at a time. For each connectivity measur...

Questions: What are the detection probabilities of epiphytic crustose lichens on oak (Quercus robur) when only the lowest 2 m of the trunk are surveyed? How does the abundance of lichen species change with height above the ground, and is the change related to tree age? How well can total abundance (0-6 m) be predicted based on data from the lowest...

Oaks (Quercus robur) can reach a considerable age, which makes them an important substrate for many epiphytic lichens, including several red-listed species. We studied the importance of tree size and other environmental factors for the occurrence of six epiphytic lichens at two sites, in southeastern Sweden, differing in quality as judged by tree s...