Stein Joar Hegland

• PhD in Ecology
• Professor (Full) at Western Norway University of Applied Sciences

QuestionsHow does the understorey plant community in a boreal forest respond to variations in red deer herbivory intensity? Do the conclusions depend on the organizational level (taxon, growth form or functional trait) used for the analyses, and does red deer herbivory create more winners or losers?LocationSvanøy, western Norway.Methods We modelled...

Plant‐pollinator interactions are highly important because of its direct link to plant fitness and because such interactions involve species at different trophic levels. Our understanding of competitive and facilitative interactions among plants for pollination is of large importance to govern conservation of species and management of crop producti...

Climate warming affects the phenology, local abundance and large-scale distribution of plants and pollinators. Despite this, there is still limited knowledge of how elevated temperatures affect plant-pollinator mutualisms and how changed availability of mutualistic partners influences the persistence of interacting species. Here we review the evide...

Dense ungulate populations in forest accompanied by high grazing intensities have the potential to affect plant population dynamics, and such herbivory effects on populations are hypothesised to differ along environmental gradients. We investigated red deer grazing and resource interaction effects on the performance and dynamics of the functionally...

Research focus on the phenology of plants has accompanied current trends in climate warming, because the two are inextricably linked. Warmer temperatures have led to advanced plant phenology in a range of systems, although some responses are species specific. However, other stressors, such as herbivory, can delay or advance plant phenology, and few...

Climate change, landscape homogenization, and the decline of beneficial insects threaten pollination services to wild plants and crops. Understanding how pollination potential (i.e. the capacity of ecosystems to support pollination of plants) is affected by climate change and landscape homogenization is fundamental for our ability to predict how su...

Climate change impacts on species and ecosystem functioning may depend on climatic context and study systems. Climate warming and intensified herbivory are two stressors to plants that often appear in combination and are predicted to increase in cold environments. Effects of multiple drivers on plant performance are difficult to predict and warrant...

Understanding how niche‐based and neutral processes contribute to the spatial variation in plant–pollinator interactions is central to designing effective pollination conservation schemes. Such schemes are needed to reverse declines of wild bees and other pollinating insects, and to promote pollination services to wild and cultivated plants. We use...

Den 29. april 2022 overleverte VKM rapporten Impacts of climate change on the boreal forest ecosystem1 (VKM Report 2022:15) til Miljødirektoratet som svar på oppdraget som er beskrevet under. I prosessen ble det bestemt at rapporten også skulle utgis i en forkortet versjon på norsk. Dette er denne utgaven. I tillegg til å forkorte og sette søkelys...

During the main COVID-19 global pandemic lockdown period of 2020 an impromptu set of pollination ecologists came together via social media and personal contacts to carry out standardised surveys of the flower visits and plants in gardens. The surveys involved 67 rural, suburban and urban gardens, of various sizes, ranging from 61.18° North in Norwa...

In this report, we summarize the current state of knowledge and best estimates of how climate change is expected to impact Norwegian forest ecosystems from now to the year 2100

Predicting plant–pollinator interaction networks over space and time will improve our understanding of how environmental change is likely to impact the functioning of ecosystems. Here we propose a framework for producing spatially explicit predictions of the occurrence and number of pairwise plant–pollinator interactions and of the species richness...

Recent increases in ungulate herbivore populations have intensified browsing pressure in northern forest ecosystems. High browsing pressure affects recruitment into tree populations and saplings are among the most impacted and critical tree stages. This calls for research on factors that enhance sapling survival and promote recovery of herbivore pr...

Ecological theory predicts the strongest ecosystem effects of herbivory when dominant and ecologically important species are consumed. Bilberry, Vaccinium myrtillus, is such a key plant species, attractive to many other species in the boreal forests, for example ungulate and invertebrate herbivores. Large herbivores may remove substantial biomass a...

The activation of plant defense systems in response to herbivory or experimentally applied methyl jasmonate (MeJA) involves the production of chemical defense substances functioning as warning signals to repel herbivores and protect against pathogens. They also serve as signals detectable by undamaged neighboring plants, a phenomenon called plant–p...

Abstract Plants have the capacity to alter their phenotype in response to environmental factors, such as herbivory, a phenomenon called phenotypic plasticity. However, little is known on how plant responses to herbivory are modulated by environmental variation along ecological gradients. To investigate this question, we used bilberry (Vaccinium myr...

Climate change is a worldwide threat to biodiversity and ecosystem structure, functioning, and services. To understand the underlying drivers and mechanisms, and to predict the consequences for nature and people, we urgently need better understanding of the direction and magnitude of climate‐change impacts across the soil–plant–atmosphere continuum...

Pollinator‐mediated reproductive interactions among co‐flowering plant species are prime examples of how species interactions may affect fitness and community assembly. Despite considerable interest in these issues, statistical methods for assessing signal of reproductive interactions in observational data on co‐flowering species are currently lack...

Background Bilberry (Vaccinium myrtillus L.) is one of the most abundant wild berries in the Northern European ecosystems. This species plays an important ecological role as a food source for many vertebrate and invertebrate herbivores. It is also well-recognized for its bioactive compounds, particularly substances involved in natural defenses agai...

Defenses induced by herbivore feeding or phytohormones such as methyl jasmonate (MeJA) can affect growth, reproduction, and herbivory, not only on the affected individual but also in its neighboring plants. Here, we report multiannual defense, growth, and reproductive responses of MeJA‐treated bilberry (Vaccinium myrtillus) and neighboring ramets....

Changes in large herbivore distribution and abundance can have effects that potentially cascade throughout the trophic structure of an ecosystem. Little is known about these indirect trophic effects of ungulate herbivory, so the aim of this study was to investigate the role of red deer (Cervus elaphus) in determining the distribution and diversity...

On 28 April 2018 the European Parliament voted for a complete and permanent ban on all outdoor uses of the three most commonly used neonicotinoid pesticides. With the partial exception of the state of Ontario, Canada, governments elsewhere have failed to take action. Below is a letter, signed by 232 scientists from around the world, urgently callin...

Browsing by ungulates may induce plant responses and affect subsequent plant food quality for other animals. Populations of many deer species have increased to unprecedented levels in Europe and North America. In Norway, population densities of red deer (Cervus elaphus) have increased over the past decades, but little is known about how increased d...

Human outdoor activities commonly affect animal behaviour. Ungulates often avoid roads and trails and increase their avoidance with expanding and intensifying human recreational activity. Recently, mountain biking has become increasingly popular in many regions in Norway, but we still have limited knowledge about how mountain biking may affect wild...

Deer-vehicle collisions (DVCs) cause animal suffering, traffic safety problems and socioeconomic costs and must be assessed in landscape planning and road management. We investigated whether landscape composition and configuration across spatial scales could predict DVCs and be used for mitigation actions and planning processes. We used data on DVC...

Aim Because the ecological similarity between species is expected to increase with relatedness and that speciation is a local process, phylogeny may provide a common measure for the influence of ecological and biogeographic processes on community assembly. We tested if similarities in floral visitation patterns within communities and the phylogenet...

Inducible plant defense is a beneficial strategy for plants, which imply that plants should allocate resources from growth and reproduction to defense when herbivores attack. Plant ecologist has often studied defense responses in wild populations by biomass clipping experiments, whereas laboratory and greenhouse experiments in addition apply chemic...

Selective herbivory can influence both spatial and temporal vegetation heterogeneity. For example, many northern European populations of free-ranging ungulates have reached unprecedented levels, which can influence plant species turnover, long-term maintenance of biodiversity and the subsequent stability of boreal ecosystems. However, the mechanism...

Wild ungulates are key determinants in shaping boreal plant communities, and may also affect ecosystem function through inducing the plant defence systems of key plant species. We examined whether winter browsing by deer could increase the resistance of bilberry (Vaccinium myrtillus). We used three indicators of induced bilberry defence: reduced gr...

Competition and facilitation in species interactions attract much attention in ecology, but their relative importance has seldom been evaluated in a community context. We assessed competitive and facilitative interactions for pollinator visitation among co-flowering species in a plant community, investigated the subsequent consequences for plant re...

Conservation practitioners often lack tools to monitor functioning of communities because time and monetary constraints create a gap between the optimal monitoring methods and the practical needs in conservation. Interaction networks provide a framework that has proven useful in ecological research. However, they are considered time consuming and t...

Background/Question/Methods Climate change affects the distribution and phenology of species and contrasting responses to climate change might cause temporal and/or spatial mismatches between interacting species. In a resent review we found a potential for both spatial and temporal mismatches in wild plant-pollinator interactions as a result of i...

Plant–pollinator interactions provide ideal frameworks for studying interactions in plant communities. Despite the large potential influence of such interactions on plant community structure, biodiversity and evolutionary processes, we know surprisingly little about the relative importance of positive and negative interactions among plant species f...

Pollen limitation on a plant community level has received little attention, although it might show which pollination-related traits may cause pollen limitation to vary among species. To address several central questions in plant reproductive biology, we investigated pollen limitation in 11 plant species, including visitation and specialisation leve...

The pollination syndrome hypothesis has provided a major conceptual framework for how plants and pollinators interact. However, the assumption of specialization in pollination systems and the reliability of floral traits in predicting the main pollinators have been questioned recently. In addition, the relationship between ecological and evolutiona...

Pollen limitation on seed production appears to be widespread among the angiosperms. However, few studies have examined if pollen limitation affects population growth. We supplementally hand-pollinated all flowers of 20 individuals of Ranunculus acris in the temperate meadow Rudsviki, Kaupanger, west Norway in 2003. The seed production did not resp...

A growing number of studies on naturally occurring plant species have shown that plant-plant interactions for pollination vary from competitive to facilitative. In reviewing the seven published studies on how alien species can affect the pollination success in natives, we found that all authors suggest competitive effects to dominate, either throug...

1. Does the diversity and abundance of one trophic level affect another? Several studies at the landscape level have found a positive relationship between the diversity of floral resources and the diversity and abundance of pollinators. However, little is known about the relationship between these trophic levels on a smaller spatial scale, and the...

The impact on the performance of dwarf shrub Vaccinium myrtillus L. (bilberry) subjected to differing natural intensities of grazing by Cervus elaphus L. (red deer) was examined in a mature Scandinavian pine forest, on Svanoy, an island on the western coast of Norway. All the study sites were in forest where bilberry dominated the forest floor and...

Knowledge about plant-plant interactions for pollinator service at the plant community level is still scarce, although such interactions may be important to seed production and hence the population dynamics of individual plant species and the species compositions of communities. An important step towards a better understanding of pollination intera...

Invasive species are regarded as one of the largest global threats to biodiversity, but little is still known about the invasion of exotic plants into tropical forests. In this paper, we examine how the size and canopy openness of human-created gaps inside the Mabira forest-reserve in Uganda, affect the invasion of one of the world's most noxious w...

1. We need to understand how threatened plant species respond to natural or management-induced habitat changes to conserve them successfully. Because long-term demographic studies are not feasible for large numbers of species, there is a clear need for simple short-term methods to assess demographic responses. 2. The population structure of 23 popu...