β-aminobutyric acid does not induce defenses or increase Norway spruce resistance to the bluestain fungus Grosmannia penicillata.

Priming of Norway spruce (Picea abies) inducible defenses is a promising way to protect young trees from herbivores and pathogens. Methyl jasmonate (MeJA) application is known to induce and potentially prime Norway spruce defenses but may also reduce plant growth. Therefore, we tested β-aminobutyric acid (BABA) as an alternative priming chemical to enhance spruce resistance, using 2-year-old Norway spruce plants.

A synchronized, large-scale field experiment using Arabidopsis thaliana reveals the significance of the UV-B photoreceptor UVR8 under natural conditions.

This study determines the functional role of the plant ultraviolet-B radiation (UV-B) photoreceptor, UV RESISTANCE LOCUS 8 (UVR8) under natural conditions using a large-scale 'synchronized-genetic-perturbation-field-experiment'. Laboratory experiments have demonstrated a role for UVR8 in UV-B responses but do not reflect the complexity of outdoor conditions where 'genotype × environment' interactions can mask laboratory-observed responses. Arabidopsis thaliana knockout mutant, uvr8-7, and the corresponding Wassilewskija wild type, were sown outdoors on the same date at 21 locations across Europe, ranging from 39°N to 67°N latitude.

Legacies of invertebrate exclusion and tree secondary metabolites control fungal communities in dead wood.

During decomposition of organic matter, microbial communities may follow different successional trajectories depending on the initial environment and colonizers. The timing and order of the species arrival (assembly history) can lead to divergent communities through priority effects. We explored how assembly history and resource quality affected fungal communities and decay rate of decomposing wood, 1.

Fungal community dynamics across a forest-alpine ecotone.

Climate change is causing upward shift of forest lines worldwide, with consequences for soil biota and carbon (C) sequestration. We here analyse compositional changes in the soil biota across the forest line ecotone, an important transition zone between different ecosystems. We collected soil samples along transects stretching from subalpine mountain birch forests to alpine heath.

Establishment of spruce plantations in native birch forests reduces soil fungal diversity.

Plantations of Norway spruce have been established well beyond its natural range in many parts of the world, potentially impacting native microbial ecosystems and the processes they mediate. In this study, we investigate how the establishment of spruce plantations in a landscape dominated by native birch forests in western Norway impacts soil properties and belowground fungal communities. Soil cores were collected from neighboring stands of planted spruce and native birch forests.

Accumulation of phenolics and growth of dioecious Populus tremula (L.) seedlings over three growing seasons under elevated temperature and UVB radiation.

Accumulation of secondary metabolites may exhibit developmentally regulated variation in different plant organs. Moreover, prevailing environmental conditions may interact with development-related variations in plant traits. In this study, we examined developmentally regulated variation in phenolic accumulation in the twigs of dioecious Populus tremula (L.

Responses in growth and phenolics accumulation to lateral bud removal in male and female saplings of Populus tremula (L.) under simulated climate change.

The responses in growth and defense after tissue damage are highly variable in plants depending on species, damaged-tissue type and the intensity of damage. The prevailing abiotic conditions can also influence these responses. In this study, our aim was to examine how the removal of lateral vegetative buds affects the growth and accumulation of phenolics in saplings of the dioecious Populus tremula grown under simulated climate change.

Ultraviolet radiation accelerates photodegradation under controlled conditions but slows the decomposition of senescent leaves from forest stands in southern Finland.

Depending on the environment, sunlight can positively or negatively affect litter decomposition, through the ensemble of direct and indirect processes constituting photodegradation. Which of these processes predominate depends on the ecosystem studied and on the spectral composition of sunlight received. To examine the relevance of photodegradation for litter decomposition in forest understoreys, we filtered ultraviolet radiation (UV) and blue light from leaves of Fagus sylvatica and Betula pendula at two different stages of senescence in both a controlled-environment experiment and outdoors in four different forest stands (Picea abies, Fagus sylvatica, Acer platanoides, Betula pendula).

The influence of spectral composition on spring and autumn phenology in trees.

Several recent reviews highlight the molecular mechanisms that underpin phenological responses to temperature and photoperiod; however, these have mostly overlooked the influence of solar radiation and its spectral composition on these processes. For instance, solar radiation in the blue and ultraviolet (UV) regions of the spectrum, as well as the red/far-red (R:FR) ratio, can influence spring and autumn phenology. Solar radiation reaching the Earth changes diurnally and seasonally; however, rising global temperatures, latitudinal range shifts and light pollution are likely to produce novel combinations of phenological cues for tree species.

Spruce and beech as local determinants of forest fungal community structure in litter, humus and mineral soil.

Beech forests reaches its native distribution limit in SE Norway, but is expected to expand substantially northwards due to climate warming. This may potentially result in a fundamental transformation of contemporary Northern European forests, with tentative effects on the associated belowground fungi. Fungal communities mediate vital ecosystem processes such as ecosystem productivity and carbon sequestration in boreal forests.

Elevated air humidity increases UV mediated leaf and DNA damage in pea (Pisum sativum) due to reduced flavonoid content and antioxidant power.

Growth in high relative air humidity (RH, >85%) affects plant morphology and causes diminished response to stomatal closing signals. Many greenhouses are prone to high RH conditions, which may negatively affect production and post-harvest quality. UV radiation induces stomatal closure in several species, and facilitates disease control.

Fertilization Changes Chemical Defense in Needles of Mature Norway Spruce ().

Nitrogen availability limits growth in most boreal forests. However, parts of the boreal zone receive significant levels of nitrogen deposition. At the same time, forests are fertilized to increase volume growth and carbon sequestration.

Elevated temperature and CO affect responses of European aspen (Populus tremula) to soil pyrene contamination.

High northern latitudes are climatic sensitive areas, and are also regions to which polycyclic aromatic hydrocarbons (PAHs) easily transport and accumulate with potential risk to natural ecosystems. However, the effect of PAHs on northern woody plant growth and defense under climate change is very little studied. Here, we conducted a unique experiment in greenhouses to investigate sex-related responses of the dioecious Populus tremula to pyrene (50mgkg) and residue of pyrene in soils under ambient and elevated temperature (+1.

Sex-related responses of European aspen (Populus tremula L.) to combined stress: TiO nanoparticles, elevated temperature and CO concentration.

The combined effects of climate change and chemical contaminants on plant performance are still not well understood. Especially, whether different sexes of dioecious plants respond differently to combined stresses is unknown. In order to study the sex-related responses of European aspen to soil nTiO contamination (0, 50, 300 mg kg) under elevated temperature (+1.

A Seven-Year Study of Phenolic Concentrations of the Dioecious Salix myrsinifolia.

In boreal woody plants, concentrations of defensive phenolic compounds are expected to be at a high level during the juvenile phase and decrease in maturity, although there is variation between plant species. Females of dioecious species, like most of the Salicaceae, are expected to invest their resources in defense and reproduction, while males are expected to be more growth-oriented. We studied age- and sex-dependent changes in leaf and stem phenolics, and in height and diameter growth in a dioecious Salix myrsinifolia plants over a seven-year time period.

Effects of long-term UV-exposure and plant sex on the leaf phenoloxidase activities and phenolic concentrations of Salix myrsinifolia (Salisb.).

The accumulation of flavonoids on the leaf surface is a well-characterized protective mechanism against UV-B radiation. Other protective mechanisms, such as the induction of antioxidative enzymes and peroxidase-mediated lignification may also be important. The effects of UV-B radiation have mainly been considered in short-term studies, whereas ecologically more relevant long-term field studies are still rare.

Effects of soil pyrene contamination on growth and phenolics in Norway spruce (Picea abies) are modified by elevated temperature and CO.

With the constant accumulation of polycyclic aromatic hydrocarbons (PAHs) in soil and increasing temperature and CO levels, plants will inevitably be exposed to combined stress. Studies on the effects of such combined stresses are needed to develop mitigation and adaptation measures. Here, we investigated the effects of soil pyrene contamination (50 mg kg) on growth and phenolics of 1-year-old Norway spruce seedlings from five different origins in Finland at elevated temperature (+ 2 °C) and CO (+ 360 ppm).

Moose selecting for specific nutritional composition of birch places limits on food acceptability.

Despite decades of intense research, it remains largely unsolved which nutritional factors underpin food selection by large herbivores in the wild. We measured nutritional composition of birch foliage () available to, and used by, moose () in natural settings in two neighboring regions with contrasting animal body mass. This readily available food source is a staple food item in the diet of moose in the high-fitness region, but apparently underutilized by moose in the low-fitness region.

Effect of climate change on bud phenology of young aspen plants (. L).

Boreal tree species are excellent tools for studying tolerance to climate change. Bud phenology is a trait, which is highly sensitive to environmental fluctuations and thus useful for climate change investigations. However, experimental studies of bud phenology under simulated climate change outdoors are deficient.

Correction to: Compositional Changes in Foliage Phenolics with Plant Age, a Natural Experiment in Boreal Forests.

The article Compositional Changes in Foliage Phenolics with Plant Age, a Natural Experiment in Boreal Forests, written by Hilde Karine Wam, Caroline Stolter and Line Nybakken, was originally published electronically on the publisher's internet portal (currently SpringerLink) on August 29, 2017 without open access.

Compositional Changes in Foliage Phenolics with Plant Age, a Natural Experiment in Boreal Forests.

The composition of plant secondary metabolites (PSMs) extensively impacts ecosystem functioning. It is vital that we understand temporal patterns in the plants' allocation of resources to PSMs, particularly those influenced by human activity. Existing data are insufficient in the long-term perspective of perennial plants (age or ontogeny).

High daytime temperature delays autumnal bud formation in Populus tremula under field conditions.

The effects of warming on autumnal growth cessation and bud formation in trees remain ambiguous due to contrasting observations between a range of studies under controlled conditions and field experiments. High night temperature has been reported to advance growth cessation and bud formation in several tree species grown under controlled conditions. On the other hand, some recent field experiments have shown that autumn warming delays bud formation, although the temperature parameters that could account for this effect have not been identified.

The vegetative buds of Salix myrsinifolia are responsive to elevated UV-B and temperature.

The predicted rise in temperature and variable changes in ultraviolet-B radiation will have marked effects on plant growth and metabolism. Different vegetative parts of trees have been studied to detect the impacts of enhanced temperature and UV-B, but the effects on buds have rarely been considered. In the present study, Salix myrsinifolia clones were subjected to enhanced UV-B and temperature over two growing seasons starting from 2009, and measured springtime bud development and concentrations of phenolic compounds.