Vaccinium Vitis-idaea Research Articles

Comparisons of Large (Vaccinium macrocarponAit.) and Small (Vaccinium oxycoccosL.,Vaccinium vitis-idaeaL.) Cranberry in British Columbia by Phytochemical Determination, Antioxidant Potential, and Metabolomic Profiling with Chemometric Analysis

There is a long history of use and modern commercial importance of large and small cranberries in North America. The central objective of the current research was to characterize and compare the chemical composition of 2 west coast small cranberry species traditionally used (Vaccinium oxycoccos L. and Vaccinium vitis-idaea L.) with the commercially cultivated large cranberry (Vaccinium macrocarpon Ait.) indigenous to the east coast of North America. V. oxycoccos and V. macrocarpon contained the 5 major anthocyanins known in cranberry; however, the ratio of glycosylated peonidins to cyanidins varied, and V. vitis-idaea did not contain measurable amounts of glycosylated peonidins. Extracts of all three berries were found to contain serotonin, melatonin, and ascorbic acid. Antioxidant activity was not found to correlate with indolamine levels while anthocyanin content showed a negative correlation, and vitamin C content positively correlated. From the metabolomics profiles, 4624 compounds were found conserved across V. macrocarpon, V. oxycoccoS, and V. vitis-idaea with a total of approximately 8000-10 000 phytochemicals detected in each species. From significance analysis, it was found that 2 compounds in V. macrocarpoN, 3 in V. oxycoccos, and 5 in V. vitis-idaea were key to the characterization and differentiation of these cranberry metabolomes. Through multivariate modeling, differentiation of the species was observed, and univariate statistical analysis was employed to provide a quality assessment of the models developed for the metabolomics data.

Decreased frost hardiness of Vaccinium vitis‐idaea in reponse to UV‐A radiation

The aim of this study was to investigate plant frost hardiness responses to ultraviolet (UV) radiation, since the few results reported are largely contradictory. It was hypothesized that functional adaptation of life forms could explain these contradictions. Dwarf shrubs and tree seedlings, representing both evergreen and deciduous forms, were tested (Vaccinium vitis-idaea, Vaccinium myrtillus, Pinus sylvestris, Betula pubescens and its red form f. rubra). The research was performed in Sodankylä, Northern Finland (67°N), with enhanced UV-B- and UV-A-radiation treatments between 2002 and 2009. Plant frost hardiness was determined using the freeze-induced electrolyte leakage method in early autumn, during the onset of the frost hardening process. Additional physiological variables (malondialdehyde, glutathione, total phenols, C and N contents) were analyzed in V. vitis-idaea to explain the possible responses. These variables did not respond significantly to UV-radiation treatments, but explained the frost hardiness well (r² = 0.678). The main finding was that frost hardiness decreased in the evergreen shrub V. vitis-idaea, particularly with enhanced UV-A radiation. No significant responses were observed with the other plants. Therefore, this study does not support the idea that enhanced UV radiation could increase plant frost hardiness.

Protection of human erythrocytes against oxidative stress by berries

Berries contain several bioactive compounds that can protect against oxidative stress. In this study we evaluated the protective effect of different sequential extracts (ethyl acetate, ethanol and water) of seven berry species: bilberry (Vaccinium myrtillus), blackcurrant (Ribes nigrum), elderberry (Sambucus nigra), lingonberry (Vaccinium vitis-idaea), rose hips (Rosa sp.), sea buckthorn (Hippohae rhamnoides) and strawberry (Fragaria × ananassa). The protective effect was tested on human erythrocytes and the antioxidant capacity was also evaluated in vitro by the FRAP assay. In the erythrocyte assay all sea buckthorn extracts were superior in antioxidant effect to other berry extracts. The ethyl acetate extract of bilberries, and the ethanol and water extracts of blackcurrants, also protected the erythrocytes from oxidation. In contrast, water extracts of rose hips, bilberries and strawberries had a pro-oxidant effect on erythrocytes. The water extract of rose hips was superior to the other berry extracts in the FRAP assay. Thus, the results of the erythrocyte assay did not correlate with the results of the FRAP assay, but provided additional insights into the potential protective effects of berry extracts against oxidative stress.

Fatty acid and phytosterol contents of some Romanian wild and cultivated berry pomaces

AbstractThe total oil content and composition of fatty acids and phytosterols of five Transylvanian (Romania) pomaces of wild and cultivated blueberries (Vaccinium myrtillus), wild cowberry (Vaccinium vitis-idaea) and raspberry (Rubus idaeus), and cultivated black chokeberry (Aronia melanocarpa), were determined by capillary gas chromatography. Out of the five pomace oils, the percentages of polyunsaturated fatty acids (PUFAs) ranged from 37 % to 69 %. The lipid classes analysed (PLs — polar lipids, TGs — triacylglycerols, SEs — sterol esters) were separated and identified using thin-layer chromatography. TGs showed the highest PUFAs content (ranging from 41.9 % to 72.5 %) and PUFAs/SFAs (saturated fatty acids) ratios (in the range of 5.8–33.1 %). In the case of PL and SE fractions, the levels of SFA were significantly higher than in TGs. The total amount of sterols was in the range of 101.6–168.2 mg per 100 g of lipids of the pomaces analysed. The predominant phytosterols were β-sitosterol, stigmastanol + isofucosterol, and campesterol. The results indicated that the investigated pomace oils, due to their good balance between n-6 and n-3 fatty acids (except for chokeberry) and high β-sitosterol content, could be excellent sources of PUFAs and phytosterols, thus suggesting potential value-added utilisation of berry waste oils for preparing functional foods or food supplements.

Lingonberry (Vaccinium vitis-idaea L.) grown in the Pacific Northwest of North America: Anthocyanin and free amino acid composition

Lingonberries and their products are popular and generally accessible in Europe, though in the US they are uncommon and considered a minor berry/fruit crop. The on-going interest in potential health benefits from berry consumption has heightened interest in broadening the selection of berry/fruit crops in the US. This study measured total phenolics, total tannins, complete anthocyanin content, and total (and individual) free amino acid composition for each of five lingonberry cultivars. Cultivars Ida, Koralle, Linnea, Sanna, and Sussi were grown in Oregon, USA, and had only been evaluated previously for their horticultural traits. All five cultivars contained the three anticipated anthocyanins (by HPLC): cyanidin-3-galactoside (main anthocyanin found in these berries), cyanidin-3-glucoside, and cyanidin-3-arabinoside. These lingonberries’ total anthocyanin content ranged from 27.4 (‘Linnea’) to 52.6 (‘Ida’)mg/100g fw. They contained 22 free amino acids (FFAs) and total FAAs ranged from 28.92 (‘Sanna’) to 70.38 (‘Koralle’)mg/100g fw. Asparagine (ASN) was the leading FAA (22–34% of the total FAAs) for all five cultivars. This is the first report on lingonberry FAA content.

Ground vegetation under natural stress conditions in Scots pine forests on fixed sand dunes in southwest Estonia

Ecosystems on dunes are influenced by critical environmental factors (mineral nutrients, water deficiency, etc.) considered decisive for their existence. The present paper is based on studies carried out on dunes on the coastal area of the Baltic Sea, southwest Estonia. The nature of forest ecosystems on dunes was studied from the aspects of chemical characteristics of soil, vascular plant species richness and diversity. Sampling sites on the dunes with different heights were selected in Cladina and in Vaccinium vitis-idaea site-type Scots pine forests. Vascular plant species richness and diversity were related to edaphic gradients. On the dune with a height of 32.1 m a.s.l., significant relationships were revealed between the number of species of ground vegetation, pH, volumetric water content in soil and the position of the sample plots. No relationships were revealed between the number of vascular plant species, soil pH, volumetric water content and mineral nutrients on the dune with a height of 9 m a.s.l. The most frequent and abundant plant species on the higher dune were Deschampsia flexuosa, Vaccinium vitis-idaea and V. myrtillus; the highest number of species were found at the bottom of the dune, while on the top only some xeromorphic species such as Festuca ovina, Sedum acre and Crepis tectorum occurred. On the lower dune, the most frequent were Vaccinium vitis-idaea, V. myrtillus and Melampyrum pratense, while V. uliginosum was found only on the bottom and slope and Empetrum nigrum on the top of the dune.

Lingonberry juice improves endothelium-dependent vasodilatation of mesenteric arteries in spontaneously hypertensive rats in a long-term intervention

Phenolic compounds of berries, fruits and vegetables affect vascular health. Endothelium-dependent vasodilatation has an important role in blood pressure development by controlling the vascular tone. Endothelial cells produce and release various relaxing and contracting factors, like nitric oxide (NO), cyclo-oxygenase (COX)-derived prostanoids and endothelium-derived hyperpolarizing factor (EDHF). The purpose of this study was to investigate whether 8 weeks treatment with Finnish berry juices, cranberry ( Vaccinium oxycoccos), lingonberry ( Vaccinium vitis-idaea) and blackcurrant ( Ribes nigrum) affects blood pressure and vascular function of spontaneously hypertensive rats (SHR). After 8 weeks treatment the mesenteric arteries of the rats were taken for vascular reactivity studies. Lingonberry treatment normalized the impaired endothelium-dependent relaxation seen in the cranberry, blackcurrant and control rats. In the arteries of lingonberry treated rats the relaxation was partly due to NO, but also dependent on EDHF. It can be concluded that long-term lingonberry juice treatment improves endothelium-dependent vasodilatation of SHR.

Two centuries of vegetation succession in an inland sand dune area, central Netherlands

Questions: (a) What are the rates and directions of vegetation succession in an inland sand-dune system? (b) What are the differences in successional trajectories in different relief types? and (c) Is it possible to preserve the last areas of still active dunes and under what circumstances? Location: The study sites were located in the northern part of the Veluwe Region, central Netherlands; longitude 5°44′ E, latitude 52°20′ N, altitude 9 to 24 m a.s.l. Methods: Vegetation and relief mapping was conducted in three permanent plots, 200 m × 200 m in size, in 1988 and 2003. Phytosociological releves (2400) were recorded in each 10 m × 10 m subplots. Age of woody species was determined by wood coring. Geographic Information System, ordination analyses, and TWINSPAN were used for data exploration and elaboration. Results: A total of 70 vascular plants and 19 bryophytes were recorded over successional stages spanning approximately190 years. The following dominant species formed the sequence of successional stages, but not all participated in all relief types: Ammophila arenaria, Festuca arenaria, Corynephorus canescens, Festuca ovina and Agrostis capillaris, and pine forest dominated in its herb layer at first by Deschampsia flexuosa and later by either Empetrum nigrum, Vaccinium myrtillus or Vaccinium vitis-idaea. Conclusions: The successional trajectory is basically unidirectional for more than 100 years; no clear multiple successional pathways were observed, as is frequent in coastal dunes. Successional divergence was observed after approximately 130 years in the composition of the herb layer in the closed pine forest. The obvious vegetation heterogeneity in the still active sand-blown area is related to differences in timing of vegetation establishment on particular relief types, thus the succession exhibits a terrain-dependent asynchronous character. We conclude that the last patches of still-active sand dunes can be preserved only by repeated strong artificial disturbances.

Plant and soil properties determine microbial community structure of shared Pinus-Vaccinium rhizospheres in petroleum hydrocarbon contaminated forest soils

Rhizosphere communities are critical to plant and ecosystem function, yet our understanding of the role of disturbance in structuring these communities is limited. We tested the hypothesis that soil contamination with petroleum hydrocarbons (PHCs) alters spatial patterns of ecto- (ECM) and ericoid (ERM) mycorrhizal fungal and root-associated bacterial community structure in the shared rhizosphere of pine (Pinus contorta var. latifolia) and lingonberry (Vaccinium vitis-idaea) in reconstructed sub-boreal forest soils. Pine seeds and lingonberry cuttings were planted into containers with an organic (mor humus, FH or coarse woody debris, CWD) layer overlying sandy mineral horizons (Ae and Bf) of forest soils collected from field sites in central British Columbia, Canada. After 4 months, 219 mg cm-2 crude oil was applied to the soil surface of half of the systems; systems were sampled 1 or 16 weeks later. Composition, relative abundance and vertical distribution of pine ECMs were assessed using light microscopy; community profiles were generated using LH-PCR of ribosomal DNA. Multivariate analysis revealed that plant and soil factors were more important determinants of community composition than was crude oil treatment. Fungal communities differed between pine and lingonberry roots; ECM communities were structured by soil layer whereas ERM communities varied between FH and CWD soil systems. Bacterial communities varied between plants and soil layers, indicating properties of ECM and ERM rhizospheres and the soil environment influence bacterial niche differentiation. This integration of mycorrhizal and bacterial community analysis contributes to a greater understanding of forest soil sustainability in forest ecosystems potentially contaminated with PHCs.

Exobasidium darwinii, a new Hawaiian species infecting endemic Vaccinium reticulatum in Haleakala National Park

Hawaii is one of the most isolated archipelagos in the world, situated about 4,000 km from the nearest continent, and never connected with continental land masses. Two Hawaiian endemic blueberries, Vaccinium calycinum and V. reticulatum, are infected by Exobasidium species previously recognized as Exobasidium vaccinii. However, because of the high host-specificity of Exobasidium, it seems unlikely that the species infecting Vaccinium calycinum and V. reticulatum belongs to Exobasidium vaccinii, which in the current circumscription is restricted to Vaccinium vitis-idaea. We collected a fresh specimen of Exobasidium on Vaccinium reticulatum in Haleakala National Park, and analysed it by a combined morphological and molecular approach. The morphological and phylogenetic analyses (based on the LSU and the concatenated ITS+LSU sequence data) showed that Exobasidium on Vaccinium reticulatum belongs to an undescribed species, distinct from Exobasidium vaccinii and any other species. The name Exobasidium darwinii is proposed for this novel taxon. This species is characterized among others by the production of peculiar witches’ brooms with bright red leaves on the infected branches of Vaccinium reticulatum. Relevant characters of Exobasidium darwinii are described and illustrated, additionally phylogenetic relationships of the new species are discussed.

Recovery of photosynthetic capacity in Vaccinium vitis-idaea during mild spells in winter

Recent studies suggest that evergreen plants may maintain their photosynthetic capacity through the winter. Since mild winters are predicted to be more frequent in the future, the metabolic activity of plants is also likely to increase. The aim of the present study was to assess how various environmental factors, such as temperature, photoperiod and preceding frost, affect the recovery of photosynthesis during a mild spell in winter. The recovery of photosynthesis was studied in a series of growth chamber experiments where the overwintering of lingonberry (Vaccinium vitis-idaea) was interrupted by an intermittent warm spell of 1 week during different phases of winter. Rapid activation was observed in all the experiments during the first 3–4 days. No obvious effects of the phase of winter or photoperiod on the recovery of photosynthesis were observed, but a severe freezing treatment prior to the warm spell retarded the recovery significantly. Once recovered, however, lingonberry was able to maintain high rates of photosynthesis even at near-freezing temperatures, which prevail in their natural sub-nivean environment. The apparent quantum yield of photosynthesis remained high through the winter for lingonberry. This may prove advantageous for evergreen dwarf shrubs which overwinter in dim environments under snow.

Diverse Helotiales associated with the roots of three species of Arctic Ericaceae provide no evidence for host specificity

Ericoid mycorrhizal fungi differ in their abilities to use nitrogen sources and may be integral to maintaining fungal and plant diversity in ecosystems in which Ericaceae occur. In this study, we tested whether the fungal communities differ among three species of co-occurring Ericaceae. Fungi colonizing Cassiope tetragona, Empetrum nigrum and Vaccinium vitis-idaea roots in the Arctic tundra were characterized via culture-dependent and culture-independent techniques. The cultured fungi were tested for their ability to colonize Vaccinium uliginosum in laboratory-based assays. The pure-cultured Helotiales were grouped into eight clades and dominated by the Phialocephala-Acephala complex. Representatives of these clades, plus an unknown basidiomycete with affinity to the genus Irpex (Polyporales), colonized V. uliginosum intracellularly. The Helotiales detected by direct PCR, cloning and sequencing were assigned to 14 clades and dominated by members of the Rhizoscyphus ericae complex. Ordination analyses indicated that culture-dependent and culture-independent assays provided distinct views of root fungal communities, but no evidence for host specificity. These data suggest that ericaceous roots host diverse fungal communities dominated by the Helotiales. However, these fungal communities are unlikely to be controlled by fungal host preferences. The mechanisms maintaining high diversity in root-symbiotic communities remain to be elucidated.

Phenolic compounds in berries and flowers of a natural hybrid between bilberry and lingonberry ( Vaccinium × intermedium Ruthe)

Hybridization between species plays an important role in the evolution of secondary metabolites and in the formation of combinations of existing secondary metabolites in plants. We have investigated the content of phenolic compounds in berries and flowers of Vaccinium × intermedium Ruthe, which is a rare natural hybrid between bilberry ( Vaccinium myrtillus L.) and lingonberry ( Vaccinium vitis-idaea L.). The berries and flowers of the hybrid showed characteristics inherited from both parent species in the distribution and contents of phenolic compounds. Bilberry is known as one of the richest sources of anthocyanins and to have a profile of 15 major forms combining cyanidin, delphinidin, petunidin, peonidin and malvidin with galactose, glucose and arabinose. Lingonberry contains only cyanidin glycosides. Hybrid berries contained all bilberry anthocyanins with pronounced cyanidin content. With regard to proanthocyanidins and flavonol glycosides, the hybrid inherited diverse profiles combining those of both parental species. The distribution of hydroxycinnamic acids was quite uniform in all studied berries. Of the identified compounds, 30 were detected in lingonberry, 46 in bilberry, 53 in hybrid berries and 38 in hybrid flowers. Hence, compared with the parent species, hybrid berries possess a more diverse profile of phenolic compounds and, therefore, can offer interesting material for breeding purposes.

Lateral Picea shadow effects on Populus tremuloides understory vegetation in central Yukon, Canada

Laterally cast Picea albertiana ssp. albertiana (western white spruce) shadows were analyzed to determine their effect on understory plant abundance in two high-latitude (62.7°N) boreal Populus tremuloides (trembling aspen) forest stands. Each stand had a uniform and continuous overstory, and occurred on level to gently sloping terrain with a submesic moisture regime. Picea >1 m tall had <20% cover in each stand, with few trees equalling or exceeding the height of the P. tremuloides canopy. Understory vegetation composition was sampled in 30-m × 30-m plots that were subdivided into 1.5-m × 1.5-m cells (200 sampled per plot). Picea shadow locations and their areal extent were determined on an hourly basis (7:00–19:00 h Pacific Standard Time on the summer solstice) for individual plot cells using silhouette diagrams constructed from tree height and canopy-related data ( n = 140 trees). Shadow data were analyzed using the lower- ( Q L , minimum to first-quartile values) and upper-most ( Q U , third-quartile values to maximum) portions of each species’ abundance distribution. Kruskal–Wallis tests ( P < 0.001) indicated that greater Arctostaphylos uva-ursi (bearberry) abundance occurred where shadow cover was the least (daytime average ∼24%); whereas Geocaulon lividum (toadflax), Hylocomium splendens (stairstep moss), and Shepherdia canadensis (buffaloberry) incurred the most shadows (>34% cover) and had the shortest periods of continuous (<6 h) sunlight exposure with <30% Picea shadow cover. Hylocomium and Shepherdia also occurred nearer Picea than Arctostaphylos. Rosa acicularis (wild rose), Linnaea borealis (twinflower), Vaccinium vitis-idaea (bog cranberry), Chamerion angustifolium (fireweed), and Calamagrostis purpurascens (purple reedgrass) incurred intermediate amounts of shadow. Differences in hourly shadow abundance values ( Q U minus Q L plot cells) were greatest for Arctostaphylos (−14.7%) and Rosa (−10.8%), but H. splendens (+3.8%) and Geocaulon had the least (+1.7%). Greater Hylocomium and Shepherdia abundance occurred in plot cells with more shadow indicating a tolerance for shade, which was contrary to the other species. These differences may represent examples of niche partitioning based on relative light availability. Individual understory species based on percent cover and species richness were more strongly correlated with Picea shadow cover than canopy cover. As a direct representation of impeded light transmittance, assessment of lateral tree shadows may represent a viable approach for investigating within stand compositional variation and temporal change among forest understory species, when a distinct physiognomic difference occurs between seral and climax overstory species.

Food Grade Lingonberry Extract: Polyphenolic Composition and In Vivo Protective Effect against Oxidative Stress

Fractionation of the polyphenols constituting a food grade lingonberry extract (Vaccinium vitis-idaea) highlighted a composition more complex than described until now in the berry. Procyanidins B1, B2, and A2 were identified by UPLC/ESI-MS(2) along with the presence of other flavanol oligomers. Processing induced the release of large amounts of aglycones for ferulic acid, p-coumaric acid, and quercetin. The described anthocyanic composition of lingonberry was completed with hexoside derivatives of peonidin, petunidin, malvidin, and delphinidin. Besides confirmation of in vitro antioxidant activity, in vivo study was performed on rats fed a diet inducing oxidative stress. Supplementation with lingonberry extract significantly decreased the total oxidant status and favorably affected antioxidant defense enzymes in red blood cells and liver. A drop in the serum reduced glutathione level was also prevented, and uric acid was maintained at low level, confirming the antioxidant activity of the extract (5% proanthocyanidins) from a dosage of 23 mg/kg of body weight.

Lingonberry (Vaccinium vitis-idaea) and European Cranberry (Vaccinium microcarpon) Proanthocyanidins: Isolation, Identification, and Bioactivities

European, small-fruited cranberries (Vaccinium microcarpon) and lingonberries (Vaccinium vitis-idaea) were characterized for their phenolic compounds and tested for antioxidant, antimicrobial, antiadhesive, and antiinflammatory effects. The main phenolic compounds in both lingonberries and cranberries were proanthocyanidins comprising 63-71% of the total phenolic content, but anthocyanins, hydroxycinnamic acids, hydroxybenzoic acids, and flavonols were also found. Proanthocyanidins are polymeric phenolic compounds consisting mainly of catechin, epicatechin, gallocatechin, and epigallocatechin units. In the present study, proanthocyanidins were divided into three groups: dimers and trimers, oligomers (mDP 4-10), and polymers (mDP > 10). Catechin, epicatechin, A-type dimers and trimers were found to be the terminal units of isolated proanthocyanidin fractions. Inhibitions of lipid oxidation in liposomes were over 70% and in emulsions over 85%, and in most cases the oligomeric or polymeric fraction was the most effective. Polymeric proanthocyanidin extracts of lingonberries and cranberries were strongly antimicrobial against Staphylococcus aureus, whereas they had no effect on other bacterial strains such as Salmonella enterica sv. Typhimurium, Lactobacillus rhamnosus and Escherichia coli. Polymeric fraction of cranberries and oligomeric fractions of both lingonberries and cranberries showed an inhibitory effect on hemagglutination of E. coli, which expresses the M hemagglutin. Cranberry phenolic extract inhibited LPS-induced NO production in a dose-dependent manner, but it had no major effect on iNOS of COX-2 expression. At a concentration of 100 μg/mL cranberry phenolic extract inhibited LPS-induced IL-6, IL-1β and TNF-α production. Lingonberry phenolics had no significant effect on IL-1β production but inhibited IL-6 and TNF-α production at a concentration of 100 μg/mL similarly to cranberry phenolic extract. In conclusion the phenolics, notably proanthocyanidins (oligomers and polymers), in both lingonberries and cranberries exert multiple bioactivities that may be exploited in food development.

Phenotypic and genotypic differentiation ofVaccinium vitis-idaeabetween coastal barrens and forests in Nova Scotia, Canada

Coastal barrens and forests are very different environments, making it surprising that some plant species grow in both habitats. Vaccinium vitis-idaea L., common in both habitats, was studied for phenotypic and genotypic differences that may correlate with the different environments. Of the measured phenotypic traits, leaf thickness demonstrated the best response to differences between habitat types. Amplified fragment length polymorphisms were used to assess the genetic diversity of 85 V. vitis-idaea plants between habitats. The overall genotypic diversity (D = 0.99) and evenness (E = 0.77) from this study were higher than that found in other studies on V. vitis-idaea, and were likely influenced by the sampling methods used. Although the harsh environment of the coastal barrens was expected to increase clonal reproduction, we found no evidence of extensive cloning in either habitat type. An AMOVA revealed that genetic variation was highest (87.8%) within populations, and that V. vitis-idaea was not genetically distinct between the coastal barrens and forests. This outcome is consistent with the hypothesis that coastal barrens and forest habitats along the Nova Scotia coast represent extremes of a successional continuum, rather than discrete plant communities.

Overwintering stress of Vaccinium vitis-idaea in the absence of snow cover

A snow manipulation experiment aimed to assess risks of direct freezing injury, freeze-induced dehydration and winter desiccation in the absence of snow cover on lingonberry ( Vaccinium vitis-idaea). Frames with sheet-plastic sides and removable lids were used in this experiment for two purposes: to prevent accumulation of snow in mid-winter and to provide extra heat during early spring. Leaves were analyzed for frost hardiness, tissue water content and osmotic concentrations, and photoinhibition (Fv/Fm) during the period from the 10th of February to the 7th of April. The natural snow accumulation was low indicated by a minor difference in minimum temperatures between the frame treatment and naturally snow-covered plots. The heating effect of the frames started gradually at the end of February along with increasing solar elevation angles, and was highest at the beginning of April. Frost hardiness peaked in March as a consequence of cold periods, but it was practically lost by the beginning of April. Tissue water content decreased gradually at first, becoming greatly decreased later due to the extra heat. In accordance, the tissue osmotic concentrations increased first gradually, followed by a dramatic increase. Photoinhibition increased uniformly with increasing solar radiation, but at the end showed a sharp increment within a few days, obviously also indicating the effect of heating. It was concluded that neither lethal freezing stress nor significant freeze-induced dehydration occurred during the experiment. However, plants that overwintered without snow suffered from severe winter desiccation injuries due to the combination of solar heat and frozen soil. Although the desiccation stress was possibly a lethal factor, it was preceded by long-term and continued photoinhibition. It was concluded that during overwintering, chamaephyte species may suffer from both freezing and winter desiccation in the absence of protecting snow cover. However, during mild winters provided by climatic change scenarios, the risk of winter desiccation will be more probable. In relation to the future climate, it was concluded that winter desiccation and photoinhibition may develop gradually during a snowless winter and would, even if they did not reach a lethal level by themselves, possibly reduce frost hardiness.

Phytosociological studies of the forests with sessile oak and Norway spruce from South-Eastern Transylvania

The forests with sessile oak (Quercus petraea) and Norway spruce (Picea abies) from south-eastern Transylvania represent a peculiar type of phytocenoses, rather unusual for the present-day vegetation of Romania’s territory. Aim of the study is to provide a detailed description of the vegetation and to identify the phytosociological and typological units to which it could belong. Beside this, stand structure and regeneration status of the main tree species are illustrated. The studied area is located around Carpathian intermountain depressions Brasov and Ciuc, where vegetation had a peculiar history and today sessile oak forests on high altitude exists, interfering with spruce forests. The hypothesis of the process naturalness is supported by vegetation history in the area, climate, stand structure and peculiarities of herb layer composition (the mixture of relic of both mountain-boreal origin and south-European origin, like Vaccinium vitis-idaea, Pyrola rotundifolia and respectively Potentilla micrantha, Lathyrus venetus respectively. Sintaxonomically, studied phytocenoses with sessile oak and spruce belong mainly to acidophilus oak forests (Luzulo luzuloidis-Quercetum petraeae), but some of them resemble oak-hornbeam forests (Carici pilosae-Carpinetum), indicating a more recent change in stand structure and suggesting that not the soil, but the climate is the driving force of succession. Regeneration of sessile oak is at least satisfactory, but the expansion of spruce in such stands could seriously restrict the survival of sessile oak. A new typological unit will be appropriate, for a better management of sessile oak forests with spruce admixture.

ライチョウLagopus mutus japonicusの餌内容の季節変化

Lagopus mutus japonicus is the southernmost subspecies of Rock Ptarmigan. This susbspecies is a relic population, remaining after the most recent ice age, isolated on mountain peaks and ridges of central Honshu, Japan, where it inhabits the alpine zone. Seasonal changes in food items were investigated by observations of ptarmigan foraging behavior on Mt. Norikura. Among the total 46,523 pecks observed throughout a year, 92.9% of them were made at vegetable matter, 4.7% at animal matter and the remaining 2.4% were made at inorganic matter such as grit. Rock Ptarmigan in Japan winter in the subalpine area below 2,600 m where their main winter food consists of the buds of Betula ermanii extending above the snow. After returning to the alpine zone in April, their main diet changed for the leaves of evergreen-dwarf-shrubs including Empetrum nigrum, Vaccinium vitis-idaea, and Arcterica nana. During May and early June they were also observed feeding on small insects, Aeolian plankton, deposited on the snow surface by updrafts from the lowlands. In addition to the leaves of evergreen-dwarf-shrubs, the flowers of deciduous-dwarf-shrubs and herbaceous plants were their main foods in summer. Many kinds of fruits and seeds are eaten in autumn. It was found that the diet of ptarmigan in Honshu, changed considerably both in quantity and in quality with seasonal changes in snow conditions and plant growth. The close relationship between the seasonal diet and the life history of the ptarmigan in the alpine environment was discussed.