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Lake-edge wetland types result from the influence of various hydrogeomorphological (HGM) predictors, such as water level, hydroperiod, and elevation. Climate and land-use changes could induce variations in lake water levels, and subsequently trigger changes in wetland type and area. This study aims to determine whether HGM predictors alone can be used to classify lake-edge wetlands. The resilience of these wetlands to different water level change scenarios was also evaluated. We sampled the plant communities of 37 lake-edge wetlands (peatland, ash and alder swamps) of a medium-size Canadian lake (12.9 km2), and computed 12 HGM predictors using a GIS software and commonly available landscape data. We used canonical redundancy analysis to evaluate the relationship between wetland types, plant communities, and HGM predictors. We then built a random forest model using these predictors to classify wetlands and to evaluate the impacts of small (± 0.5 m) and large (± 2 m) water level changes on wetland type and area. Our results show that elevation and slope were the two main HGM predictors of wetland plant communities and types. The random forest model was robust (89 % accuracy), but performed less well for swamps, likely because alder and ash swamps are similar systems, but at different successional stages. Finally, while small water level changes had minimal impacts on lake-edge wetland type and area (−0.6 %), larger changes triggered substantial gains (+ 13 %) or losses (−20 %) of tree-dominated wetlands. Considering that swamps harbour high species richness, landscape management should be carried out bearing in mind their greater vulnerability.

Past work shows a significant negative correlation between foliar oregonin concentration and western tent caterpillar (Malacosoma californicum Packard) feeding on red alder (Alnus rubra Bong.). Above an oregonin threshold of 20% leaf dry weight, little feeding by caterpillars is observed. Concentrations of defensive chemicals are influenced by plant genotype, environmental conditions, insect feeding, and the interactions of these factors. Our objective was to measure the effects of nitrogen (N) availability and wounding on foliar oregonin and condensed tannin concentrations in red alder genotypes. One-year-old seedlings from 100 half-sib red alder families were treated with two levels of ammonium nitrate (NH4NO3) for two growing seasons in a common garden. In the second year, leaves from 50 families from the fertilization experiment were used in a bioassay feeding experiment to determine the effects of N fertilization and genotype on WTC damage, and to identify a subset of 20 families with a range of damage to analyze for phytochemical composition. In separate experiments, wound-induction treatments were conducted outdoors and, in a greenhouse using the N treated trees in their third and fourth year, respectively. Foliar condensed tannin, oregonin and N concentrations were measured and ranked among the plant genotypes, and between the two N treatments and two wounding treatments. Results showed that oregonin and condensed tannin concentrations varied among the alder genotypes. Leaf N concentration was negatively correlated with concentration of oregonin. Neither of the measured phenolic compounds responded to wounding. The results suggest that red alder foliar oregonin and condensed tannin are likely constitutive defenses that are largely determined by genotype, and that the negative correlation of defense compounds with plant internal N status holds in this N-fixing tree.

Pollen threshold values used in public warning systems are intended to inform people of the risk of developing allergy symptoms. However, there is no consensus about which pollen concentrations provoke allergy symptoms. The aim of this systematic review was the evaluation of studies investigating the relationship between pollen concentrations (alder, ash, birch, hazel, mugwort and ragweed) and the number of cases in which participants visited a doctor, drug consumption and allergy symptoms. This systematic literature review is registered in PROSPERO (CRD42019112369). A PubMed search was applied and enriched by consultation with experts and a snowball strategy. The included studies were checked for risk of bias (RoB), and extensive data were extracted and compared. Of 511 studies, 22 were eligible according to the previously established inclusion criteria, and 17 from these showed a low RoB. The strongest evidence was reported for ash (Fraxinus) pollen, where an increase of number of doctor’s visits at an interquartile range (IQR) of 18–28 grains/m3 was detected by three studies. Five studies about birch (Betula) pollen showed a threshold value of 45 grains/m3 for increased drug consumption. The evidence of a threshold value was limited for alder (Alnus), hazel (Corylus), mugwort (Artemisia) and ragweed (Ambrosia) pollen. The inconsistent results concerning all types of pollen, except ash pollen, can be the result of multiple factors, e.g., age, gender, allergen content of pollen and individual sensitivity. These influencing factors should be investigated more closely in future research.

The twig method in climate chambers has been shown to successfully work as a proxy for outdoor manipulations in various experimental setups. This study was conducted to further establish this method for the investigation of allergenic pollen from tree species (hazel, alder, and birch). Direct comparison under outdoor conditions revealed that the cut twigs compared to donor trees were similar in the timing of flowering and the amount of pollen produced. Cut twigs were able to flower in climate chambers and produced a sufficient amount of pollen for subsequent laboratory analysis. The addition of different plant or tissue fertilizers in the irrigation of the twigs did not have any influence; rather, the regular exchange of water and the usage of fungicide were sufficient for reaching the stage of flowering. In the experimental setup, the twigs were cut in different intervals before the actual flowering and were put under warming conditions in the climate chamber. An impact of warming on the timing of flowering/pollen characteristics could be seen for the investigated species. Therefore, the twig method is well applicable for experimental settings in pollen research simulating, e.g., accelerated warming under climate change.

Calla palustris is a circumboreal species native to wetland habitats of the Northern Hemisphere. Information about the complex distribution, vegetation and ecology of C. palustris in Slovakia is still missing and scattered in several local published sources and herbaria. Therefore, we decided to (i) characterise its distribution and ecological pattern, and (ii) provide a complex vegetation affiliation of the species in this territory. C. palustris has been reported from almost 30 localities concentrated in the northern part of Central Slovakia, especially in the Zapadne Beskydy Mts. The number of records rapidly decreases towards southern and eastern Slovakia. The species prefers nutrient-poor and acidic sites in regions with humid and relatively cold climates. A vegetation analysis of available phytosociological releves revealed the presence of C. palustris in the vegetation of mires (classes Scheuchzerio-Caricetea fuscae, Oxycocco-Sphagnetea, Vaccinio-Piceetea), alder carrs (Alnetea glutinosae class) and marshes (Phragmito-Magnocaricetea class). The major environmental gradients responsible for the variation in species composition of the vegetation were analysed in Detrended correspondence analysis (DCA) using Ellenberg indicator values for vascular plants. The first DCA axis corresponded to the amount of nutrients, soil reaction and temperature. Based on our study, the inclusion of C. palustris among vulnerable species within the Slovak Plant Red List is considered correct.

In many watersheds, nitrogen (N)-fixing alder (Alnus spp.) provides key nutrient subsidies to terrestrial and aquatic ecosystems. The importance of these subsidies may increase as alder cover expands under climate warming at high latitudes. We assessed how landscape features and meteorological conditions affect aquatic N and phosphorus (P) availability and stoichiometry in 26 streams across natural gradients of alder cover in southwestern Alaska over the spring and summer, covering 4 years. Analyses of resin lysimeter samples from select watersheds showed that annually, soils under alder leached almost three times more N, and two times more P than under non-alder vegetation. Stream NO3− concentrations displayed a non-linear relationship with alder cover; NO3− was low where alder cover was 30%. Watershed elevation was inversely related to alder cover, stream NO3− concentrations, and stream NO3− yields. Dissolved and particulate stream P were unrelated to alder cover, watershed elevation or discharge, highlighting decoupling of controls on P between terrestrial and aquatic ecosystems. Snowmelt-associated nutrient pulses and hydrology likely resulted in greater stream N and P in the spring, compared to the summer. However, weather parameters only impacted stream N via their interaction with alder. Stream DIN:TP increased with alder cover and decreased with elevation, suggesting that alder intensified P-limitation. Hence, aquatic P-limitation may become increasingly pronounced as climate-induced alder expansion continues. These results demonstrate that the elevational gradient in watershed alder cover determined spatial patterns in stream N availability and nutrient limitation.

Converting data from national forest inventories to carbon stocks for greenhouse gas reporting generally relies on biomass expansion factors (BEFs) that expand stem volumes to whole tree volumes. However, BEFs for trees outside forests like trees in hedgerows are not yet included in the IPCC reports. These are expected to be different from forest trees as hedgerow trees are exposed to more solar radiation and have more growing space. We present age-dependent BEF curves for hedgerow-grown pedunculate oak (Quercus robur L.), common alder (Alnus glutinosa (L.) Gaertn.) and silver birch (Betula pendula Roth). We scanned 73 trees in northern Belgium using terrestrial LiDAR (Light Detection and Ranging). Via quantitative structure models, we estimated total volume and stem volume (diameter greater than 7 cm); we then calculated BEF as the ratio of total volume to stem volume. BEFs decreased exponentially with tree age, converging at 1.18, 1.9 and 1.92 for alder, birch and oak, respectively. For alder, this value is comparable to values of forest-grown alder; for birch and oak, these values are substantially higher, indicating a bigger part of the total volume is branch wood instead of stem wood. Total wood volume in hedgerows varied from 131.2 to 751.8 m3 per running kilometre, accounting for 30.0 to 222.8 Mg carbon stored, respectively. Only half of the produced wood in hedgerows was classified as stem wood, the other half as branch wood. Our findings show that hedgerow-specific BEFs should be used when applications for biobased economies are drafted. Also, hedgerows should be included in national carbon budgets as they represent non-negligible stocks.

Plants synthesize a wide range of bioactive secondary metabolites to defend against pests and pathogens. Red alder (Alnus rubra) bark, root, and leaf extract have a long history of use in traditional medicine and hygiene. Diarylheptanoids, especially oregonin ((5S)-1,7-bis(3,4-dihydroxyphenyl)-5-(β-D-xylopyranosyloxy)-heptan-3-one), have been identified as major bioactive constituents. Diarylheptanoids have become a focus of research following reports of their antioxidant, antifungal, and anti-cancer activities. Recent data suggest that high oregonin concentration is associated with resistance of red alder leaves to western tent caterpillar (Malacosoma californicum) defoliation. Here we test effects of this compound directly on leaf-eating insects. Purified oregonin was examined in insect choice and toxicity tests using lepidopteran caterpillars. The compound exhibited significant anti-feedant activity against cabbage looper (Trichoplusia ni), white-marked tussock moth (Orgyia leucostigma), fall webworm (Hyphantria cunea), and M. californicum at concentrations corresponding to oregonin content of the most resistant alder clones in previous experiments. Toxicity tests were carried out with cabbage looper larvae only, but no contact or ingested toxicity was detected. Our results suggest that oregonin at levels found in red alder leaves early in the growing season may contribute to protecting red alder from leaf-eating insects.

Phenology provides intimate insights into ongoing changes in nature and seasonality with respect to humans. In this study, the most complete volunteer observer phenological data set for the territory of Latvia from 1970 to 2018 was evaluated. The data set includes observations of 159 phases of eight taxonomical groups, as well as abiotic phenomena such as the first snow, last spring frost, and agrarian activities. With reducing dimensionality, a hierarchical cluster analysis was used to group the 66 phenological phases of most observations into 7 clusters. The largest changes were observed in the early spring phenological phases of the pioneer species such as the start of flowering of Corylus avellana (hazel), Alnus incana (grey alder) and Populus tremula (aspen), noted as -8 days/decade. The trend of the spring emergence of insects and spring migratory birds also showed a negative tendency. The phenology of crops and agrarian activities has not changed significantly. The trends of the autumn phases were heterogeneous-leaf colouration and fall for some species (Populus tremula) and (Acer platanoides, Norway maple) was recorded on average later; for other species, there was a slightly earlier trend (Betula pendula, silver birch; Tilia cordata, linden). Earlier onset of the spring phases affects the changes in the length of the growing season (for Acer platanoides + 7.7 days/decade; Betula pendula + 3.3 days/decade). Since 1990, it has been common that many phases have begun sooner (particularly spring phases), whilst abiotic autumn phases have been characterised by late years. This study has shown that significant seasonal changes have taken place across the Latvian landscape due to climate change.

Summary Background Globally, climate change is being observed. Pollen allergies have been increasing since the middle of the last century. Outdoors, sensitization against pollen allergens is responsible for the highest prevalence of allergies of eyes and airways. Hence, the following two questions arose: (1) How does climate change become manifest locally–regionally, and do temperatures and precipitation have to be considered exceptional in 2018? (2) How do changing meteorological conditions impact on pollination and pollen load? Methods Pollen data of the main allergenic plants—collected at the pollen monitoring station Linz, Upper Austria—were analysed; 2018 was compared to the years 1993–2017. By means of statistical methods, the impact of meteorological parameters on pollen seasons and pollen load were examined. Results Climate change was confirmed for the region. The regional climate has shifted from moderate to warmer and drier (semi-arid) conditions. Preseasonal cumulated meteorological parameters determined flowering and pollen seasons (PS). Start and duration of the pollination of hazel, alder, birch, and grass followed other rules than the seasonal pollen production, termed seasonal pollen integral (SPIn). By its hybrid character, the model-year 2018 offered the unique chance to generate and explain different scenarios of pollen emission and transmission. For the start of flowering of hazel (Corylus), alder (Alnus) and birch (Betula), the coincidence of cumulated mean daily warmth (MDWcumul) and a distinct threshold for the highest temperature of a day (HTD) is necessary and species-specific. In 2018, the earliest begin of the pollen season (PSB) was observed. Frost delayed the PSB. Preseasonal frost as well as cool temperatures caused SPIn of alder and birch to rise, whereas SPIn of hazel were increased by warmer temperatures. Warm weather prolonged pollen seasons of early flowering plants. Heat combined with drought shortened PS of birch in 2018. Cumulated relative humidity (RHcumul) correlated highly significant with the PSB of grasses. Warm and dry conditions in 2018 caused the earliest PSB of grass since 1993. Over the years, SPI and major pollen peaks of grasses have decreased, primarily due to dryness. Conclusion The assumption that climate warming in Linz over 26 years should have increased pollen concentrations of allergenic plants was not confirmed. On the contrary, trend analyses showed that the pollen load has decreased. Hence, the increase in sensitization to pollen allergens and of the prevalence of pollen allergies ask for other explanations.

The physiological and biochemical parameters and elemental composition of Hypogymnia physodes lichen samples from various phytocenoses differing in lighting conditions and atmospheric humidity were studied. A significant increase in the chlorophyll a and nitrogen contents, the maximal pheophytinization coefficient, and the minimum content of phenolic compounds were observed in H. physodes thalli under severe shading conditions in a spruce forest. Most of these biochemical parameters reached their minimum values with high insolation in birch and pine forests except for the content of phenolic compounds, which reached the maximum value. ICP–AES analysis of H. physodes thalli detected 20 elements (Al, B, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Pb, Sn, Sr, Tl, V, W, Zn) that were found in lichen samples from all studied natural phytocenoses except for Mo, which was absent in samples from a black alder forest. The maximum concentrations for almost half of the elements (Al, B, Fe, K, Mo, Na, Sn, Ti, V) were determined in samples from the spruce forest where the thalli were more often and consistently hydrated because of the high and more stable humidity level. A complex system of correlation relationships was established based on an analysis of cross-correlations of the physiological and biochemical parameters and the metal concentrations in the samples. The results indicated a high coordination of various physiological processes. Chlorophyll a played a crucial role in maintaining their consistency with changing environmental conditions. Its content was associated with a more significant number of different parameters and elemental concentrations.

A protocol has been developed for the propagation of Alnus glutinosa axillary shoots in liquid medium. The explants were cultured in Woody Plant Medium supplemented with 0.1 mg l− 1 benzyladenine and 0.5 mg l− 1 indole acetic acid. The effect of the bioreactor type (RITA® and Plantform™), frequency of the immersions, regulator concentrations, and volume of medium per explant was investigated. All the treatments with the temporal immersion systems (TIS) increased the proliferation rates. The best results were obtained on using the Plantform™ vessels and, unlike the shoots cultured in RITA® vessels, the culture in Plantform™ had very low hyperhydricity percentages. Shoots originating from the culture in semi-solid medium and in Plantform™ rooted in semi-solid medium with 0.1 mg/l indole butyric acid for 7 days. No significant differences were observed in the rooting or acclimatization percentages, with survival percentages greater than 85% being achieved. This is the first work on the use of TIS systems in alder propagation, with the results of this study providing new perspectives for its mass propagation., The authors would like to thank INLUDES (Diputación Provincial de Lugo) for the initial funding received for starting the works on alder micropropagation, as well as for the facilities provided to collect the material.

Aboveground dead wood has a range of important ecological functions, including carbon (C) storage. According to the Intergovernmental Panel on Climate Change guidelines for National Greenhouse Gas Inventories established on the basis of the United Nations Framework Convention on Climate Change and the Kyoto Protocol, Lithuania is encouraged to quantify C pools in forests, including C in living biomass, soil and dead wood. The aim of this study was to assess species-specific dead wood density (DWD) and carbon content (CC) per decay class for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.), silver birch or downy birch (Betula pendula Roth or Betula pubescens Ehrh.), European aspen (Populus tremula L.), grey alder (Alnus incana (L.) Moench), black alder (Alnus glutinosa (L.) Gaertn.), common oak (Quercus robur L.) and European ash (Fraxinus excelsior L.), as the main representative hemiboreal forest tree species. The study findings revealed that mean DWD significantly decreased, while mean CC slightly increased during the wood decomposition process, which led to carbon density (CD) reduction over five decay classes. The mean CC showed little variation among the eight tree species and ranged between 47 and 54%. The lower CDs in the dead wood of decay classes 1 and 2 were more associated with coniferous than deciduous species. The estimated CD significantly decreased in all species with increasing decay class. Dead wood at decay class 5 of Scots pine, silver or downy birch, European ash and common oak had the highest CD, followed by Norway spruce and grey alder, and the lowest CDs were obtained for European aspen and black alder.

Floodplain forests, as diverse plant communities commonly related to riparian zones, host plant species with various ecological niches and origins. The phytosociological context of floodplain forests has been well described on national level in many European countries, however, there are still regions with relatively poorly known variability of their species composition and environmental drivers controlling their vegetation patterns. Vegetation sampling of floodplain forests using traditional European phytosociological approach along with the recording of environmental (climatic, edaphic, topographic) variables was carried out in the northern part of the Western Carpathians (Slovakia and Poland) in period of 2011–2016. We gathered dataset of 135 original phytosociological releves, which were classified using modified TWINSPAN algorithm. Five associations were distinguished: (i) meso-eutrophic black alder swamp forests (Carici acutiformis-Alnetum glutinosae), (ii) montane oligotrophic mixed spruce-alder forests on waterlogged sites (Piceo abietis-Alnetum glutinosae), (iii) riparian willow forests (Salicetum fragilis), (iv) meso-hygrophilous riparian alder forests (Stellario nemorum-Alnetum glutinosae) and (v) riparian grey alder forests (Alnetum incanae). Canonical Correspondence Analysis (CCA) with forward selection was used to show effect of environmental factors on species composition variation. The explained variance declined from marginal (13.9%) and conditional (8.6%) to pure effect (7.5%), with altitude (1.6%), total soil nitrogen content (1.6%) and soil pH (1.4%) being the most important predictors accounted for the highest variation in species compositional data.

Alnus pollen has been frequently detected in the atmosphere of different airborne sampling sites of Southern Spain. However, Alnus sp. populations are very scarce and fragmented in the area, being restricted to a few river valleys in the southwest, and other further away regions of the Iberian Peninsula. This leads to think that the airborne pollen detected could be mainly the result of a medium- or long-distant transport. So, the aim of this study was to characterize the annual patterns of airborne Alnus pollen detected at three different locations of Malaga province, as well as to determine its possible origin, the pollen dispersion potential of these Alnus isolated populations, and their possible reproductive connectivity. Pollen sampling was conducted by means of three Hirst-type volumetric pollen traps. Samples were mounted and counted following the recommendations of the Spanish Aerobiology Network and the European Aeroallergen Society. The possible pollen sources were detected by means of a combination of meteorological information and backward air trajectories analysis. A high inter-annual variability in the annual pollen integrals was found in all the stations, favouring certain meteorological conditions a long-range transport and, therefore, causing the high concentrations detected in some specific days. Alnus pollen seems to have a heterogeneous origin with prevalence of the long-distant transport, which would suggest a possible reproductive connection among distant populations.

Symbiotic nitrogen- (N) fixing trees can influence multiple biogeochemical cycles by fixing atmospheric N, which drives net primary productivity and soil carbon (C) and N accumulation, as well as by mobilizing soil phosphorus (P) and other nutrients to support growth and metabolism. The soil micronutrient molybdenum (Mo) is essential to N-fixation, yet surprisingly little is known of whether N-fixing trees alter soil Mo cycling, and if changes to soil Mo are coupled to soil C, N, and P. We compared how symbiotic N-fixing red alder and non-N-fixing Douglas-fir trees modified surface soil C, N, P, and Mo across variation in climate and other site factors in the Pacific Northwest. We found that after two decades, N-fixing trees drove coupled increases in surface soil C, N, total P, and organic P. Consistent with contributions of N-fixing trees to soil organic matter, increased soil C and N were accompanied by lower δ13C in all sites, and lower δ15N in sites where non-fixer plots exhibited elevated soil δ15N. However, N-fixing trees did not affect surface soil Mo concentrations or fractions, suggesting that different factors control the cycling of P versus Mo over decadal timescales. Random forest analysis revealed that surface soil P was most strongly influenced by factors related to soil C accumulation, whereas surface soil Mo was related primarily to environmental factors, including potential differences in atmospheric Mo deposition across sites. Ratios of surface soil P:Mo were higher in extractable pools than in total soil digests, reinforcing the idea of stronger biotic cycling of P than Mo. Overall, our multi-site, multi-decadal field study found surprisingly small effects of N-fixing trees on soil Mo, despite rapid increases in soil organic C, N, and P. We hypothesize that, rather than direct effects of N-fixing vegetation, abiotic or indirect biotic factors such as soil sorption of atmospheric Mo inputs can link C–N–P–Mo cycles in terrestrial ecosystems on longer timescales.

Powerful alluvial rivers in the northern Alborz mountain ranges erode river banks due to having high slopes. Most of these rivers flow in forest areas. In this research, the rate of the river bank erosion was examined using the exposed roots of the trees. For this purpose, 8 reaches of Lavij Stream were investigated. To determine the first year of root exposure, two sets of macroscopic and microscopic indicators were utilized. Accordingly, the rate of the stream bank erosion was estimated. The results were analyzed by using statistical test, which showed insignificant differences between the two groups of indicators. Due to its more abundance (frequency) on the margins and easy detection of its root through the exposure (macroscopic and microscopic) indicators, Alnus glutinosa (black alder) species could be more easily and accurately analyzed as compared with any other tree species in the region. The mean erosion rate of the riverbank using the extruded roots was estimated to be 0.08 m/yr. The hydrological analyses of flood flows showed that 95% of Lavij Stream bank erosion was caused by the river bank full discharges with a return period of 1–3 years.

Wild pear (Pyrus pyraster (L.) Burgsd.) (P) and wild service tree (Sorbus torminalis (L.) Crantz) (S) are sporadic European tree species that are valued for their high-quality timber production. Although mixed plantations including companion species enhance timber quality of several trees, the performance of the association of P and S is not well known. The objective of this study was to assess growth and survival of P and S in pure plantations and in plantations mixed with other companion tree or shrub species in a non-native habitat. To answer the question of whether growth of these species is enhanced by mixtures, specific combinations of the main and companion species were established in central Chile and monitored for a 12-year period after planting. Besides each main species monoculture, five mixtures were tested: Mix1: P+S; Mix2: P+S+ the N-fixing tree Italian alder (Alnus cordata (Loisel.) Duby); and three associations of P and S including shrubs (Mix3: P+S+ Corylus avellana L., Mix4: P+S+ Sambucus ebulus L., and Mix5: P+S+ Sambucus nigra L.). Both P and S presented the highest height growth in Mix2, being 48.6% and 53.4% higher than in the monoculture, respectively. DBH growth was also enhanced in Mix2 for S. Wild service tree, which showed lower growth and survival than P, was more benefited from the mixture including Italian alder than P. Height growth, vigor and survival of the main species were highest in Mix2, even higher than in pure plantations and in Mix1 without companion species. Specific tree associations might increase the probability to obtain high-quality timber of noble species if a timely and adequate management of companion species is provided.

Plant interactions with single symbionts of nitrogen fixing bacteria or mycorrhizal fungi are well studied. However, less is known about how plants interact with multiple symbiont species. The aim of this study was to assess whether multiple symbionts had a synergistic effect on host plant performance compared with a single symbiont and whether increasing the number of non-specific fungal species would increase plant performance due to niche complementarity. Green alder (Alnus viridis ssp. crispa) were inoculated with non-specific ectomycorrhizal fungi (Lactarius torminosus, Lactarius theiogalus, Hebeloma crustuliniforme) alone or in combination, with and without Frankia, and grown in nutrient-poor soil. Frankia significantly increased plant growth by 48.5%, doubled the proportion of plants forming ectomycorrhizae, as well as increased root extracellular phosphatase activity by 8.8% compared to non-Frankia treatments. However, increasing number of fungal species decreased nodulated plant biomass. Plants that formed a Hartig net had reduced nodule number and nodule biomass allocation, as well as total nodule activity compared with plants with no Hartig net. Our results indicated that Frankia inoculation provided benefit for both host plants and ectomycorrhizal fungi in the nutrient-poor soil, while ectomycorrhizal fungi did not. These negative effects of mycorrhizal fungi are likely dependent on soil nutrient P availability.

Leaf litter decomposition in streams is a fundamental ecosystem process that allows for the cycling of nutrients. The rate at which leaf litter decomposes is greatly controlled by its intrinsic characteristics. However, intraspecific variation in leaf litter characteristics poses a major challenge for large-scale studies aiming at identifying the environmental moderators of leaf litter decomposition. Thus, several standardized organic substrates have been proposed as surrogates for leaf litter. Tea bags were proposed as a standardized alternative to leaf litter for studies in soil and their use in aquatic ecosystems has been growing in recent years. It is therefore necessary to evaluate how tea is colonized and decomposed by aquatic microbial decomposers to assess its usefulness as a surrogate for leaf litter in litter decomposition studies. Here we compared the microbial colonization (based on the reproductive activity of aquatic hyphomycetes) and decomposition of green and rooibos teas and native alder leaf litter in two streams differing in environmental conditions. Colonization of green tea was lower than that of alder leaf litter, but their decomposition rates were similar. In contrast, colonization of rooibos tea was similar to that of alder leaf litter, but it decomposed 3–4 × slower. Results were consistent in both streams. Despite differences in magnitude, dynamics of microbial colonization and decomposition of tea were similar to those of alder leaf litter and were sensitive to substrate characteristics. Tea may be used as a surrogate for leaf litter in studies addressing microbial-driven leaf litter decomposition in streams.

The effects of local and regional environmental variables as well as spatial gradients on the plant species composition of two types of alder-dominated forests (riparian forests and alder carrs) with contrasting connectivity were studied across the Western Carpathians from Hungary through Slovakia to Poland. We used large vegetation (240 sampling plots) and environmental (24 variables) datasets, which were accompanied by spatial variables represented by principal coordinates of neighbour matrices. Canonical correspondence analysis (CCA) of the two datasets revealed 13 and 29 variables with significant effects on variation in species composition of alder carrs and riparian alder forests, which jointly explained 41.2% and 36.4% of the variability, respectively. Altitude was the most important factor explaining 7.7% of the variability in the species composition of alder carrs and 8.2% in riparian alder forests. Variation partitioning in CCA revealed that local variables were crucial drivers for species composition patterns in alder carrs, while spatial processes unrelated to the measured environmental variables shaped the vegetation structure of riparian forests.

Phytoplasmas are associated with hundreds of plant diseases worldwide including many economically important crops. These bacteria are limited in their plant hosts to the phloem sieve tubes and are transmitted by phloem sap-sucking insect vectors. Research on these pathogens is hampered by the unavailability of axenic cultures and established cultivation methods despite their importance. Alder yellows (AldY) phytoplasma frequently infects Alnus spp. (black alder), and is closely related to the economically important phytoplasma causing Flavescence doree (FD) in grapevines, a quarantine pathogen. AldY strains had been transmitted to grapevines through an occasional grapevine-feeding vector from alders; consequently, AldY share a common European origin with FD. In contrast to FD, no phytoplasma typical infection-associated symptoms such as yellowing and decline can be observed for AldY. Here, we summarize the current state of the art of phytoplasmosis of black alder (Alnus glutinosa). The symptomless phytoplasmosis might be an interesting model for investigating host tolerance strategies in phytoplasma/host interactions.

Orientation of leaves in a mature hemiboreal mixed broadleaf stand (the Jarvselja RAMI birch stand) was measured using the high-density point cloud of terrestrial laser scanner hits. Leaf normal distribution in the upper part of crowns of tall aspen and birch trees is almost spherical, and slightly planophile in the lower part of crowns. Leaves of alder trees are rather planophile in the upper part of crowns, and strongly planophile in the lower part of crowns. Lime and maple trees form the lower layer of trees in the stand. Their crowns are mainly in shade, and therefore, their leaf orientation is strongly planophile throughout the whole crown. Parameters of beta distribution and elliptical distribution are provided for the approximation of empirical distributions. The acquired information about leaf orientation can improve performance assessment of radiative transfer models.

Desorption atmospheric pressure photoionization (DAPPI) is an ambient mass spectrometry (MS) technique that allows the analysis of both polar and nonpolar compounds directly from the surfaces of various sample types. Here, DAPPI was used to study the chemical profiles in different parts of birch and alder tree barks. Four distinct fractions of Betula pendula (silver birch) bark were collected from three different developmental stages of the stem, after which the chemical profiles of the different tissue types were measured. Of special interest were triterpenoids, a class of important defensive substances, which are found in the bark of the silver birch. Additionally, the chemical profiles of lenticels and the surrounding surfaces in the phellem of B. pendula (silver birch), Alnus glutinosa (black alder), and Alnus incana (gray alder) were screened with DAPPI. Another ambient MS technique, laser ablation atmospheric pressure photoionization (LAAPPI), was further used for the mass spectrometry imaging of lenticels on the B. pendula phellem. All the studied birch bark fractions showed individual chemical profiles in DAPPI. The mass spectra from the young apical stem and the transition zone resembled each other more than the mature stem. Instead, the phellem was found to contain a high amount of triterpenoids in all the developmental stages of the stem. The most intense peaks in the DAPPI mass spectra of the birch bark fractions were those of betulin and lupeol. Betulinic and betulonic acid peaks were intense as well, and these compounds were detected especially in the lenticels of the tree samples.

Although air pollution at the Central European “Black Triangle” sites has decreased since the 1990s, its legacy has persisted. Unlike the dominating Norway spruce that was planted again in order to restore forest cover, deciduous broadleaves were expected to improve soil. The objective of the study was to compare effect of N-fixing green alder on forest floor and soil properties compared to Norway spruce of comparable age. Forest floor layers [diagnostic horizons: litter (OL), fermentation (OF) and humified (OH)] and topsoil (A) were sampled in three replicates where green alder (GA), Norway spruce (NS), and mixture (GA + NS) were growing. Upper (OL, OF) horizons were affected positively where green alders were present and effect on OH and A horizons was weaker. Properties of GA + NS were in general intermediate to GA and NS. The improvement in soil was manifested by higher nutrient pools of N, P, K, Ca, and Mg in both OL and OF; more dry matter, organic carbon and higher cation exchange capacity were shown in OF and lower acidity in all analyzed horizons. Lower P concentrations were found in GA, nevertheless with no effect on P-pools. Forest floor and topsoil conditions confirmed green alder’s capability for improving chemistry of the formerly polluted mountain soil.

Shrub expansion has occurred across much of the arctic tundra over the past century. Increasing dominance of woody vegetation is expected to have global influences on climate patterns and lead to local changes in hydrological function and nutrient cycling. Changing abiotic conditions associated with shrubs will likely alter the relative fitness of neighbouring plants resulting in distinct community composition. Here, we use an extensive set of paired abiotic and biotic data to investigate the capacity for Alnus alnobetula (green alder) patches to modify the habitat of the local plant community at the taiga–tundra ecotone of the Northwest Territories, Canada. Plots were established across topographic positions in ten alder patches and adjacent, alder-free tundra. Habitat corresponded to the strongest gradient of among-site variation in abiotic measures and plant community composition, indicating that alder patch growing conditions were distinct from those of alder-free tundra. Slope position was generally unimportant in determining environmental conditions. Alder patches changed the vertical structure of the understory by increasing the maximum height of birch. Tall shrubs also decreased the richness of tundra specialists, suggesting that these species face competitive pressures from shrub expansion at the southern edge of their ranges. Our findings demonstrate that tall shrub patches can substantially modify their local environment in taiga–tundra ecotone systems, altering available habitat and acting as niche constructors for the local plant community. These habitats will therefore be important to consider in regional predictions of hydrology, nutrient cycling, and biodiversity as shrubs continue to expand across the arctic.

Simulations of soil organic carbon (SOC) stocks under climate change are partly subject to uncertainties deriving from the Global Climate Models (GCMs) used for weather projections of future climates. For this reason, SOC simulations are generally performed with a set of GCMs to avoid misleading results. SOC stocks were measured in different land covers in a forest area of Northern Iran (maple, alder, oak, cypress and a mixed natural forest), and the model RothC was used to predict SOC changes under climate change scenarios. We studied the effects on SOC stock changes deriving from an ensemble of nine GCMs and two Representative Concentration Pathways (RCPs), projected on four future periods (FPs) of 20 years between 2020 and 2099. The frequency analysis of SOC stock changes indicated a different effect of the GCMs/RCPs ensemble in the four future periods, with patterns showing more evident nonlinear probabilities of SOC changes in the 2030s and 2050s compared to the almost linear probabilities in the remaining future periods. This would imply that the effect of the GCMs/RCPs ensemble is more important in very close and intermediate future scenarios (the 2030s and 2050s) compared to fully realized climate change scenarios (the 2070s and 2090s). Results indicated the need to provide assistance in the management strategies in the reforestation sector in close and intermediate climate change scenarios. In fact, maple and quercus plantations had the highest probability of cumulated SOC change proving more sensitive to climate change. Conversely, cypress and alder plantations could limit the decrease of SOC stocks representing a good option for GHG mitigation in close and intermediate climate change scenarios and should be preferred in the afforestation of the degraded natural forest, and in mixed plantation systems within maple and oak stands.

Phytophthora is an important plant pathogen that can cause serious damage in a wide range of forest species. Understanding how this pathogen disseminates is fundamental to disease management. There is a continual need for improvement of Phytophthora species monitoring in natural ecosystems. However, currently there is little evidence for whether avian vectors may be transporting spores and contributing to the spread of the pathogen. This is the first survey of birds as vectors of Phytophthora species. Analysis of swabs from feathers from 112 birds belonging to seven species showed that most of them transmit P. cactorum and to a lesser extent P. plurivora. Pathogens of black alder − P. alni and P. multiformis were detected in the investigated area, but their frequency was low. This study showed that avian vectors are important in spreading Phytophthora. In addition, analysis of swabs from feathers can be sensitive method for detection of Phytophthora presence in ecosystems.

Alnus subcordata (Caucasian Alder, Betulaceae) is known as one of the most important tree species in wood industry with high nitrogen fixation capability and high rate of biomass production. In recent years, a disease symptom with the characteristics of alder bacterial leaf spot has been reported from the forests in Mazandaran province, Iran. To characterize the leaf spot causal agent, samplings were conducted from infected trees in different regions of Mazandaran forests. Characterization of the bacteria isolated from symptomatic tissues was performed based on classical and molecular methods. Twenty colonies were purified and tested by PCR using primers X1 and X2 specific for the genus Xanthomonas and biochemical analyses as well. Based on molecular and phenotypic identifications, the isolates were identified as genus Xanthomonas. Phylogenetic analysis was carried out based on PCR amplification and sequencing of gyrB genes for 14 selected isolates. Consequently, according to the molecular data all recovered isolates were determined as X. arboricola. Furthermore, multilucus sequence analysis using gyrB, fyuA, dnaK and rpoD for various pathovars of X. arboricola showed that our isolates clustered in a single clade sister to X. arboricola pv. juglandis. The results of pathogenicity tests on alder leaves seedlings confirmed that all the isolates were pathogenic and caused leaf spot on A. subcordata. To the best of our knowledge, this is the first comprehensive study on the molecular identification of the alder bacterial leaf spot disease in Iran.

Application of mulch on compacted soil is a common engineering measure to suppress runoff and soil loss during ground-based mechanized forest operations. Despite the expanded use, efficacy of these rehabilitation treatments on soil quality as well as seedling survival and growth rate are crucial issues that require further attention. This study aimed to assess the efficacy of two soil amendment techniques including straw (1.27 kg m−2) and litter (1.67 kg m−2) mulch on soil properties and growth properties of Caucasian alder. Three treatments: straw mulch (SM), litter mulch (LM) and untreated trail (U) were applied on newly established machine operating trails subjected to low, medium, and high machine traffic intensity classes and compared to the undisturbed area (i.e., control; UND). Approximately 22 months after ground-based machine traffic and mulching application, seeds of Caucasian alder were sown in each treatment and in the undisturbed area and further extracted after the first growing season to assess their growth rates. Three years after applying mulch on the compacted soil, recovery values of soil physical and chemical properties (with the exception of soil C/N ratio) in all traffic intensities were significantly higher in LM than SM, compared to U treatment. Nevertheless, recovery values of soil physical and chemical properties were still higher than values in UND area over a 3-year period. All the measured growth and biomass responses of Caucasian alder seedlings changed significantly with increasing traffic intensities (all P ≤ 0.05). Significantly higher seed germination percentage was recorded in LM with low traffic intensity (54%). Significantly higher seedling stem height (17.3 cm), main root length (23.6 cm), seedling total (7.68 g), shoot (2.87 g), and root dry (4.81 g) biomass were observed in the UND area followed by LM with low traffic ≈ LM with medium traffic treatments, whereas the lowest values of seedling size and biomass were detected on U with low, medium, and high traffic intensities. Seedling root mass ratio (RMR; 61%) and root to shoot ratio (R/S; 1.89) were greatest in the UND area, while the RMR (40%) and R/S (0.86) were least in the U plots with high traffic intensity. We can conclude that the highest seedling growth, biomass, and allocation ratios and favorable soil physical, chemical, and bio-chemical properties can be attributed to UND, LM with low and medium traffic, and SM with low traffic treatments.

Information about nutrient dynamics is of upmost importance in order to contribute to the restoration of degraded forest environments in the Andes of southern Ecuador. This study aims to investigate the differences of nutrient dynamics between a native alder (Alnus acuminata) and an exotic pine (Pinus patula) tree species in this region. Based on litterfall, forest floor and mineral topsoil (0–20 cm) of two pine and two alder plantations, we studied the litterfall production and its seasonality; temporal variations of nutrient concentrations, stoichiometric ratios and potential nutrient return (PNR) of leaf-litterfall; mean residence times (MRT) of nutrients in the forest floor; and assessed soil biogeochemical properties. Our results showed that total litterfall production in pine was twice as high as in alder. Litterfall biomass seasonality was similar for both species and highly associated to periods with less precipitation. Pine exhibited the highest seasonality of nutrient concentrations and stoichiometric ratios. PNR of N, K, Ca, and Mn exhibited the major differences between the species. The annual PNR of N and Ca were higher in alder, while those of K and Mn were higher in pine. Pine exhibited higher MRT values for C, N, P, S, Cu, and Zn, while alder showed the higher for Mg, K, Mn, and Ca. In soils, alder exhibited higher concentrations and stocks of nutrients, but not for C. Although, the soil microbial biomass was similar under both species, microbial activity was different. C and net N mineralization were higher in alder, and nitrification dominated over ammonification processes. In general, our findings show a faster cycling of nutrients in alder than in pine.

The radical scavenging activity and the content of proanthocyanidins, tannins, flavonoids, and total phenolic compounds in water extracts from whole bark and outer bark of alder (Alnus glutinosa (L.) Gaertn.), oak (Quercus robur L.) and pine (Pinus sylvestris L.) trees growing in the coastal and continental zones in Kaliningrad region (Russia) were evaluated. The content of proanthocyanidins was highest in extracts from whole alder bark collected in continental zone (3.8 ± 1.2 mg g−1), which was 34–38 times more than in outer part. No significant difference in tannin content in alder and oak bark extracts was revealed. Pine bark samples had less tannins. The whole alder bark showed higher content of flavonoids (9.7–21.5 mg g−1), compared to oak bark (7.2–8.4 mg g−1) and, in particular, pine bark (2.1–5.2 mg g−1). The maximal total phenolic content was found in whole alder bark from continental zone (29.0 ± 5.3 mg g−1). High content of phenolic compounds was determined in whole oak bark (about 18.1 ± 3.5 mg g−1). All investigated species showed approximately 1.3–2.5 times lower total phenolic content in outer bark in comparison to whole bark. Maximal radical scavenging activity of alder extracts (up to 276 ± 29 mg g−1) and minimal of pine extracts (up to 23.8 ± 4.0 mg g−1) was established. A higher level of radical scavenging activity for all samples from continental zone in comparison to samples from coastal zone was revealed. Based on the results of a cluster analysis, it was first demonstrated that the phenolic compounds content and radical scavenging of bark extracts are influenced by a complex of factors, such as tree species, part of the bark and the place of growth. The results of this study proved that whole bark of alder may be considered as a valuable source of phenolic compounds with radical scavenging properties.

Trophic interactions between birds and their prey often vary among habitat types, but they are poorly studied in low-latitude regions. We assessed the seasonal effect of larval abundance on the breeding performance of the Green-backed Tit (Parus monticolus), a caterpillar specialist, in broadleaf (mixed-oak forest) and coniferous (conifer plantation) habitats in subtropical Taiwan. We measured the biomass of Lepidoptera and Hymenoptera larvae in five tree species: two evergreen oaks and one deciduous alder in broadleaf habitat and two conifers in coniferous habitat. Alder supported a high larval biomass peak in early spring, dominated by noctuid and sawfly larvae, while the two oaks had later, lower peaks. The diversity of trees in the broadleaf habitat supported a broad food peak, spiking in early spring and gradually declining. In contrast, the coniferous habitat had a comparatively lower larval biomass that increased slightly over the season and included a high percentage of hairy lithosiines. Habitat-specific seasonality in larval abundance affected nestling conditions. Early-brood nestlings in the broadleaf habitat were heavier than those in the coniferous habitat. However, the between-habitat difference disappeared in the late broods because the mass of nestlings in the coniferous habitat increased significantly. We found a linear relationship between nestling condition and the total larval biomass available at demand peaks, but there were no differences in annual breeding density, late-brood frequency, laying date, clutch size, or fledging success between the two habitats. Food availability constrained nestling growth but not survival. Habitat-related trophic interactions are present in these subtropical montane forests.

A study was carried out to explore soil bacterial diversity associated with Himalayan Alder (Alnus nepalensis)-based shifting cultivation system in Khonoma Village, Nagaland. This agricultural system is well known for its traditional and sustainable form of shifting cultivation and natural biodiversity conservation in the Eastern Himalayan region of India. Surface soil samples (0–30 cm) were collected from alder-based crop fields in Khonoma, Nagaland, and brought to the laboratory for soil nutrient analysis and isolation of culturable bacteria. Standard methodologies were followed for soil nutrient and bacterial diversity analysis. Isolated bacteria were identified using 16S rDNA spacer sequence analysis. BLAST and phylogenetic analysis of molecular sequences identified a unique bacterial isolate in the soil. 16S rDNA partial sequencing of this bacterial strain showed 99% similarity with Kosakonia sacchari–type strain SP1T which has been named for its association with sugarcane. K. sacchari KhAn is a free-living, aerobic, gram-negative, non-spore-forming, and motile rod-shaped bacterium. This bacterial strain holds diazotrophic potential as it was able to grow in nitrogen-free medium and positive for nifH amplification. Furthermore, it showed positive test for ammonia production in peptone water. The soil under alder-based farming system was rich in organic carbon (3.60 ± 0.17%), available nitrogen (536.67 ± 9.28 kg ha−1), available phosphorous (77.35 ± 4.19 kg ha−1), and exchangeable potassium 127.88 ± 10.62 kg ha−1. The existing literature revealed that K. sacchari has not been reported from India until now; therefore, this is the first novel report from India. This contribution represents Eastern Himalaya, a Biodiversity hotspot of the country.

Leaf litter processing is an essential ecosystem function in freshwater systems, since much of the carbon and nutrients moving through freshwater food webs come from the surrounding terrestrial ecosystems. Thus, it is important to understand how the species performing this function differ, especially because many native species are being replaced by non-native species in aquatic ecosystems. We used a field experiment to examine leaf consumption rates of two common shredding macroinvertebrates (the native Gammarus fossarum and the non-native Gammarus roeselii). Leaves from three species, varying in resource quality, were added both in leaf monocultures and as a three-species mixture. Biomass-adjusted daily consumption rates were similar between the two amphipod species, and each consumed nitrogen-rich alder leaves faster than oak or beech leaves. However, because adult G. roeselii are approximately twice the size of G. fossarum, this led to systematic, though nonsignificant, differences in consumption rates at the per-capita or population level. Furthermore, we found nuanced effects of decomposer identity on leaf decomposition in mixtures. Only G. roeselii showed increased consumption of the preferred resource (alder) in the mixture, while G. fossarum consumed all leaves at the same proportional rates as in monocultures. This is an important distinction, as most measures of macroinvertebrate leaf shredding are made in the laboratory with only a single leaf resource available. Our results, based on a field experiment which could control the presence of dominant macroinvertebrates while still providing natural, biologically realistic context, suggest that even functionally similar species may subtly shift ecosystem processes.

The furniture sector worldwide is rapidly developing and diversifying. The furniture market faces nowadays a competition between various composites and solid wood furniture which is more reliable and environmentally-friendly. Various valuable species, such as oak, ash, and cherry, in addition to other common hardwood and softwood species are chosen by small- or medium-sized furniture companies. Due to its workability, properties, and appearance, black alder can be considered a suitable material for furniture manufacturing. This review offers an outline of the potential of black alder as a wood resource with an emphasis on applications in the furniture industry. Results from recent studies that have focused on active silviculture, uses, wood properties, color changes under air and light exposure, surface quality of processed surfaces during milling and sanding, coating properties, and process optimization are presented. Findings of these studies would help for practical applications so that this wood species can be processed more efficiently for value-added products with enhanced surfaces, improved appearance, and extended service life. Black alder as an under-utilized wood species has been shown to have good potential for the wood industry so that its use can successfully reduce import activities of other species and value-added furniture products can be manufactured. For further studies, the properties of plywood made of densified veneers, surface wettability, and coating performance of such products should be evaluated for the furniture industry.

Background and aims The aim was to assess possible benefits or drawbacks of arbuscular-mycorrhizal (AM) and ectomycorrhizal (EM) colonisation compared to no mycorrhizas (NM) in seedlings of the same host species. Eight broadleaf species were tested for mycorrhiza formation. Grey alder (Alnus incana) and four fungal species were selected for further experiments. Methods Grey alder seedlings were inoculated with AM fungi Rhizophagus intraradices and Glomus hoi or EM fungi Paxillus involutus plus an ascomycete isolated from Alnus roots or mock-inoculated (NM). Results EM formed in 70% of root tips and AM in 30% of root length. AM plants were smaller than EM and NM, but their specific root length (SRL) and specific leaf area (SLA) were highest. Net photosynthesis, stomatal conductance and shoot water potential did not differ between treatments. Foliar Ca, K, Mg, Mn, N, P and S concentrations (mg g−1) were highest in AM plants. However, total foliar contents (mg per plant) were lowest in AM plants, except for P, K and Zn. Conclusions The larger SRL and SLA suggest more efficient resource usage in AM plants, even though these were smaller than EM and NM plants. Grey alder is proposed as a new model species for comparisons between mycorrhiza types in cold climates.

The effects of mixing different leaf litter species on litter decomposition in streams have received considerable attention in recent years. However, contrasting results have been reported and the mechanisms behind the effects of litter diversity have been poorly examined. We compared the decomposition rates and associated fungi for two contrasting litter species, when incubated individually and in mixture, at two different current velocities. Coarse-mesh bags with alder litter individually, oak litter individually and with a mixture of both were incubated in a forest headwater stream over 32 days, under fast or slow current velocities. We determined litter decomposition rates, microbial oxygen consumption rates, and aquatic hyphomycete sporulation rates, species richness and community composition; litter species in the mixture were processed individually. Our results provided weak evidences for diversity effects on leaf litter decomposition. Generally, litter decomposition was unaffected by mixing contrasting litter species, with litter species in the mixture decomposing at the same rate as when incubated individually at both current velocities. The same pattern was observed for microbial variables. Decomposition rates and microbial colonization and activity depended primarily on the traits of the target litter species and were not affected by those of the companion species. However, litter-mixing effects were detected on oak litter at late decomposition stages under fast current velocity conditions, suggesting that both current velocity and the incubation time might influence diversity effects on litter decomposition in streams. This finding contributes to explain the lack of litter-mixing effects reported previously by many studies.

Plants have difficulty absorbing phosphorus from volcanic ash soils owing to the adsorption of phosphorus by aluminum and iron in the soils. Thus, on volcanic ash soils, the phosphorus source for natural vegetation is expected to be organic matter, however, there is a lack of experimental evidence regarding this occurrence. Here, we studied the effect of organic matter on plant growth of some species that occur in primary successions of volcanic ash soil ecosystems, based on growth experiments and chemical analyses. We found that a large amount of inorganic phosphorus (but only a limited amount of inorganic nitrogen) is leached from fresh leaf litter of the pioneer spices Fallopia japonica at the initial stage of litter decomposition. Phosphorus from the fresh litter specifically activated the growth of subsequently invading nitrogen-fixing alder when immature volcanic soil was used for cultivation. In contrast, old organic matter in mature soil was merely a minor source of phosphorus. These results suggest that fresh litter of F. japonica is essential for growth of nitrogen-fixing alder because the litter supplies phosphorus. We consider that rapid phosphorus cycles in fresh litter-plant systems underlie the productivity of natural vegetation even in mature ecosystems established on volcanic ash soils.

Exploratory hybridization of red alder (Alnus rubra Bong.) and white alder (Alnus rhombifolia Nutt.) was conducted to initiate a long-term investigation into the inter-specific taxon’s potential for biomass production. Red alder selections originated in stands west of Oregon’s Cascade Mountains, while white alder came from provenances west and east of the Cascades. White alder’s heretofore unknown chromosome number was determined equal to red alder (2n = 2x = 28) and included a pair of satellite chromosomes. An experimental crossing technique was proven, establishing the species’ reproductive affinity for the first time. Hybridization was substantially more productive when red alder served as the female parent as opposed to white alder. Hybridity was confirmed using four species-specific SSR markers developed from transcriptome resources for identifying sib relationships in domesticated populations. To begin a description of the inter-specific taxon, hybrids and their open-pollinated siblings were assessed at ages four through six for morphological and phenological traits and carbon and nitrogen isotopic ratios in a field planting in western Washington, USA. Principal component analysis of quantitative leaf and internode morphologies showed that red alder and hybrid alder are relatively comparable and both are distinct from white alder. Qualitative differences in leaf morphology are more diagnostic with inter-specific hybrids often intermediate to red and white alder. Principal coordinate analysis of molecular data cleanly separated the three taxa. Plans for continued investigation of the taxon as a biomass crop species are discussed including a potential role for inter-specific hybrids in adapting red alder to the effects of climate change.

In this paper, the analyses of wood remains from weapons that were found in early medieval graves in Belgium are presented. In addition, a large number of wood identifications from other early medieval weaponry from northwestern Europe (Germany, France, Switzerland, and England) was collected, resulting in a dataset of more than 800 items. The analysis of this dataset shows that the selection of wood taxa for specific weapons was largely similar all over northwestern Europe during this period and this selection can be explained by the physical and technical properties of each of these wood species. For instance, common ash (Fraxinus excelsior) being the preferred wood for arrow and spear shafts and alder (Alnus sp.) for scabbards. However, some regional differences emerged from this extensive dataset, e.g., the use of holly (Ilex aquifolium) for the production of axe handles being restricted to northern Belgium and poplar/willow (Populus sp./Salix sp.) being the preferred wood for shields in the UK, while these were mostly made from alder (Alnus sp.) in continental Europe. The results demonstrate the added value of wood anatomical analysis of mineralized wood particles preserved in the corrosion layer of metal objects, and weapons in particular, from archeological contexts. Clearly, taxonomic identifications have the potential to shed more light on material culture, technological craftsmanship, and the burial ritual in early medieval societies.

Although there is greater awareness of spatial variability of factors affecting plant growth, regression methods with residuals independently and identically distributed, are still used. Thus, we compared spatial and non-spatial regression models in evaluating the relationships between tree growth of different species and clones and environmental factors in a polycyclic tree plantation of Italy (about 20-ha size). Soil samples were collected at 106 georeferenced locations and analyzed for the main soil parameters; trunk diameter was measured for 2513 trees and used as a proxy of plant growth; geostatistical procedures were applied to soil data so as to map soil characteristics. Poplar and alder cover indices and altitude as a proxy of groundwater depth were estimated at each tree location. The study provides evidence that considering spatial correlation can: (i) reduce the possibility of falsely declaring significant effects (Type I errors), and (ii) perform more precise predictions. Overall the model choice influenced the identification of significant regressors and the trunk diameter predictions, leading to implications on management decisions, quantitative estimation of wood productions and species comparisons. The spatial model showed which specific factors had a significant impact on plant growth and for which of them spatial variability might be worth investigating: the impact of soil texture on tree growth was evident, with difference among the investigated species and clones; soil organic carbon content affected poplar tree growth but not that of the valuable species; alder cover promotes development of trees; unlike the poplar trees, the trunk growth of the valuable species was limited by carbonate content.

Assessment of soil nutrients and fertility status for three land use systems was carried out in Mokokchung, Nagaland, which lies under Eastern Himalayan region. Soil fertility indicators, viz., bulk density, soil pH, soil organic carbon, available Nitrogen (N), available Phosphorus (P), and available Potassium (K) were analyzed for Alder based fallow Jhum, Jhum and fallow Jhum lands, using standard procedures. Significant differences were observed in the soil properties, where the risk of top soil erosion along with nutrients was found to be more in Jhum lands. Alnus nepalensis (Alder) based fallow Jhum land system was found superior as significantly higher soil organic matter (3.20%) was detected that contributed to soil fertility and better nutrient cycling. Therefore, Alder based land use system may be replicated in other Jhum lands or areas for maintaining soil nutrients and soil fertility that is important for sustaining biodiversity and soil fertility.

The paper traces the early stages of Berni Alder's scientific accomplishments, focusing on his contributions to the development of Computational Methods for the study of Statistical Mechanics. Following attempts in the early 50s to implement Monte Carlo methods to study equilibrium properties of many-body systems, Alder developed in collaboration with Tom Wainwright the Molecular Dynamics approach as an alternative tool to Monte Carlo, allowing to extend simulation techniques to non-equilibrium properties. This led to the confirmation of the existence of a phase transition in a system of hard spheres in the late 50s, and was followed by the discovery of the unexpected long-time tail in the correlation function about a decade later. In the late 70s Alder was among the pioneers of the extension of Computer Simulation techniques to Quantum problems. Centered around Alder's own pioneering contributions, the paper covers about thirty years of developments in Molecular Simulation, from the birth of the field to its coming of age as a self-sustained discipline.

Differences among individuals within species affect community and ecosystem processes in many systems, and may rival the importance of differences between species. Intraspecific variation consists of both plastic and genetic components that are regulated by different processes and operate on different time scales. Therefore, probing which mechanisms can affect traits sufficiently strongly to affect ecosystem processes is fundamental to understanding the consequences of individual variation. We find that a dominant deciduous tree of Pacific Northwest riparian ecosystems, red alder, exhibits strong and synergistic responses to nutrient resources and herbivory stress. These induced responses, which include shifting nutrient and plant secondary metabolite composition, have cascading effects on aquatic ecosystem function. Defense responses suppress leaf litter decomposition in small streams, thus altering the rate of energy capture for one of the most abundant terrestrial carbon sources entering aquatic systems. We find that alder responses to herbivory stress largely depend on availability of soil nutrients, with modification of the highly cytotoxic diarylheptanoid group of secondary metabolites being favored in nutrient-poor environments and modification of the typically dose-dependent ellagitannins being favored in nutrient-rich environments. Importantly, these findings identify traits for herbivore resistance in alder trees and demonstrate that plastic responses occurring within a species and over short time scales substantially alter a key function of an adjacent ecosystem. Furthermore, demonstrating plasticity among alder secondary metabolites lends insight into this system, in which decomposer communities are known to adjust to the secondary chemistry of local alder trees to facilitate rapid decomposition of locally derived leaf litter.

This paper analyses long-term (1960–2015) onset of flowering in 16 native terrestrial plants (11 of them produce important allergens) recorded in different parts of the Czech Republic (southern, central and northern part) in relation to the North Atlantic Oscillation (NAO) index of the preceding winter and thermal data—growing degree-days (GDD) and soil temperature. Flowering occurred significantly earlier following positive winter NAO phases (causing spring to be warmer than normal in Central Europe) in nearly all early-flowering (February, March, April) species; high Pearson correlation values were recorded in, e.g. wood anemone, common snowdrop, goat willow, common hazel and common alder. There was found a difference between the southern and northern part of the country, e.g. in silver birch and pedunculate oak. Out of the later-flowering (May–July) plant species, black elder and meadow foxtail also significantly correlated with the winter NAO index, lime tree correlated less markedly. The best results of a threshold for calculation of GDD to onset of beginning of flowering were found in lime tree—it was 5 °C at all three stations. Results of other taxa were more variable (e.g. 4–7 °C in goat willow; 6–10 °C in silver birch). Pearson correlation coefficients between NAO index and GDD were negative in lime tree at all thresholds (5, 6, 7, 8, 9, 10 °C), while goat willow and silver birch were not so uniform (both positive and negative values). Correlation coefficients between phenophase onset and soil temperature (10 cm depth) had the highest values in silver birch, European larch and wood anemone. Stations situated at higher elevation showed negative correlation coefficient with soil temperature in common snowdrop, pedunculate oak, meadow foxtail and lime tree; other values were positive.

For the first time in Belgium, fluctuations in airborne pollen quantities over a 34 years period have been analyzed. Seven pollen types have been selected comprising the most clinically relevant in Belgium nowadays (birch, alder, hazel and grasses) and others that are known to be allergenic in other European countries and frequently found in Belgium (plane, ash and mugwort). Pollen monitoring was performed with a seven-day recording volumetric spore trap placed in Brussels. We measured increasing airborne pollen for four trees, namely alder, hazel, ash and plane. Although the total pollen index for birch has not increased significantly, an increasing trend in the annual amount of days above the concentration threshold of 80 pollen grains/m3 was clearly observed. Concerning temporal variations, the pollen season has tended to end earlier for birch, ash and plane and the peak concentration of the pollen of plane has been appearing earlier in the year. In the investigated period, the pollen seasons of grasses and mugwort have tended to become less severe. Furthermore, we reported a temporal shift of the grass pollen season, beginning and ending earlier, together with an advance of the annual peak date.

The aim of the study was to estimate how the deadwood of different tree species in various stages of decomposition affected nutrient dynamics. The deadwood of eight species (common alder, common aspen, common ash, silver fir, pedunculate oak, Norway spruce, common hornbeam and silver birch) was selected. Three logs from each species in the third, fourth and fifth decay classes were chosen for analysis. Wood in the third decay class was characterised by larger hard fragments, fragmented bark and no branches; in the fourth decay class, it was characterised by small pieces and a fragmented bark; and in the fifth decay class, it was characterised by a soft texture and no bark. The investigation was carried out in the Czarna Rozga Reserve in Central Poland. Tension lysimeters were installed under each log in the humus horizon. The water samples collected from tension lysimeters were chemically analysed in the laboratory. The water chemistry was analysed by means of ion chromatography using a DIONEX ICS 5000 unit. The leachate obtained from different tree species contained different ion concentrations. The high similarity of the concentration of total anions and statistically significant differences in the content of total cations were determined in the leachate from the wood of coniferous and deciduous species. The concentration of the cations increases with the advancement of the decomposition level. A general linear model analysis demonstrates that wood species and the decomposition classes are of equal importance in defining the ion composition of the filtrate leaching from deadwood. Wood at the highest decomposition stage releases more ions to the surface soil layers than wood at the lower decay class. An exception from the rule is the wood of birch, which in the III decay class releases more ions than in its higher decay classes. When comparing the ionic composition of leachate released from wood of coniferous and deciduous tree species, the latter are characterised by higher cation concentrations in comparison with coniferous species. Among the deciduous species, wood of such species as ash, hornbeam, aspen, birch and alder has the most favourable effects on the soil surface horizons through its supply with ionic substances. The ash wood releases high amounts of calcium, hornbeam wood releases magnesium and sodium, and aspen releases calcium, potassium and nitrate anion. From the analysed coniferous species, fir wood has a more favourable effect in terms of ion release to soil than spruce wood.

This article presents the results of the wood identification of 3,867 everyday objects dated from the 9th to the 15th century ad, which were excavated from 48 medieval strongholds and early urban centres in Poland. The analyses have shown that medieval craftsmen used the wood of 27 tree and shrub taxa. The timber used the most was Pinus sylvestris (pine), Quercus sp. (oak), Fraxinus excelsior (ash) and Alnus sp. (alder). Pine was used mainly to make vessels out of staves (curved pieces of wood) such as buckets and tubs, and for torches for lighting; oak was used for furniture, barrels, cart axles, spades and club hammers used by carpenters. Ash wood was the main material used for making turned bowls, and alder for making articles which were to be in long-lasting contact with water, such as beaters and scoops. Wood studies agree with historical records about the intensive use of yew wood, which finally caused the decrease of Taxus baccata in woodlands in the 14th and 15th centuries. Also, the wood of shrubs such as Euonymus sp. (spindle) and Sambucus sp. (elder) was quite often used. The choice of wood for the specific needs of a particular craft in medieval Poland was done selectively and it was determined by the particular function of the object being made, but at the same time it was limited by availability from the local woodlands. Regional differentiation in the selection of raw material is best indicated in the case of Abies alba (fir). Chronological analysis of the use of wood shows that the number of items made of timber from deciduous trees in all regions of Poland decreased in the late Middle Ages when compared to the Piast period of the early Middle Ages.

Although plants are recognized as conduits for soil-produced N2O, little is known about N2O fluxes from mature trees under field conditions as well as their contribution to total (soil + stem) N2O fluxes. Exclusion of tree-mediated N2O may thus underestimate total forest N2O fluxes. In the present study, our aims were to quantify tree-mediated N2O emissions and their seasonal patterns. We investigated in situ stem and soil N2O fluxes from mature alder trees on poorly-drained soil and mature beech and spruce trees on well-drained soils during March–October 2015. Alder, beech and spruce consistently emitted N2O via stems and all displayed clear seasonal patterns. Soil and air temperature, vapor pressure deficit, and soil N2O concentration influenced the temporal variability of stem N2O fluxes. Stem and soil N2O fluxes from the alder stand were higher than beech and spruce stands. Stem N2O fluxes accounted 8.8–9.8% of the total N2O fluxes in the beech and spruce stands but only 1.1% in the alder stand. Our study reveals the importance of field-based measurements across seasons in order to come up with reliable estimates of stem N2O fluxes. N2O estimates from temperate forests that are solely based on soil N2O flux measurements are probably conservative.