Pinus Cembra Research Articles

Slow and diverse: Upslope expansion of tree species since 1854 in the Bavarian Alps (Germany) detected by citizen science

ABSTRACT We motivated mountain hikers to survey high-altitude occurrences of selected tree and shrub species in the Bavarian Alps in a citizen science portal and compared the observations with historical data collected by the botanist Otto Sendtner at the end of the Little Ice Age. For nine of ten species with sufficient numbers of historical and citizen science observations, currently uppermost outpost occurrences were verified after data curation and subsampling. Tree species of montane (Sorbus aucuparia: 342 m, Abies alba: 324 m, Acer pseudoplatanus: 273 m, Fagus sylvatica: 141 m) and of lower subalpine distribution (Betula pubescens: 278 m, Picea abies: 55 m) climbed significantly, whereas species found at the high subalpine tree line ecotone ascended less (Pinus mugo: 21 m, Larix decidua: 13 m, Alnus alnobetula: 6 m) or even appeared to lose elevation (Pinus cembra: −57 m). We explain the gap between realized and potential upslope shift of ca. 500 m suggested by the thermal elevation gradient by the lack of mature soils at high altitudes and low summit heights in the Bavarian Alps.

Holocene vegetation change at Grosssee, eastern Swiss Alps: effects of climate and human impact

AbstractPollen, spores, and microscopic charcoal from the sediments of Grosssee (1,619 m a.s.l.), a small lake in the lower subalpine vegetation zone of the Glarus Alps, Switzerland, were analysed to reconstruct vegetation patterns and land use over the past ca. 12,300 calibrated 14C years bp (cal bp). Pollen data revealed an open landscape covered with grasses and herbs such as Artemisia during the Late Glacial Period. The catchment was likely initially afforested with Betula and Pinus cembra or Pinus sylvestris during the Early Holocene. Thermophilous taxa such as Ulmus, Tilia, and Alnus glutinosa-type expanded from ca. 11,000–9,200 cal bp, and mesophyllic Picea abies and Fagus sylvatica followed, and expanded beginning from ca. 8,000–7,600 cal bp. Interestingly, Alnus viridis (synonym: A. alnobetula) expanded about 2,000 years earlier than at comparable sites in the northern Swiss Alps. Its expansion was profound and persistent, and percentages > 15% were already achieved by ca. 7,000 cal bp. Local erosion events that followed are well explained by vegetation changes and inferred human land use activities at Grosssee. In particular, this led to a more open landscape, and land uses (e.g. grazing) intensified from the Mid- to Late Holocene. Indicators of environmental disturbance including persistently high levels of A. viridis, monolete fern spores, and microscopic charcoal were pronounced after ca. 4,000 cal bp. At that time, high influxes of spores from coprophilous fungi and the consistent presence of cultural indicators (Cerealia-type, Plantago lanceolata) indicate increased grazing and high levels of human impact. Land use and grazing activities seemed to have been particularly pronounced and to have promoted diversity in the vegetation over the past 1,000 years.

Adaptability of Swiss Stone Pine (Pinus cembra) in Two Different Environmental Conditions of Romanian Carpathians

Swiss stone pine (Pinus cembra) is a feasible solution for increasing the resistance of future mixed spruce–pine stands to windfall at the upper altitudinal limit of Romanian forests. This study aims to analyze the adaptability of ten full-sib families in two different environmental conditions and their evolution in time for predicting forward selection. At a seedling age of 33, evaluations were carried out for survival rate (Sr), growth (diameter at breast height—Dbh, and trees’ height), and branch traits, as well as for stem straightness. The high level of genetic variability, inheritance rate, and trait–trait correlations, registered in both trials, ensure the success of the breeding program. The Swiss stone pine shows a very good adaptation on high-sloping lands from the upper altitudinal limit of Romania’s forests, with the cross-pollinated (CP) families registering a 28.5% better survival in the Rodna trial (34° slope) compared to the Păltiniș experiment (7° slope). The consanguineous families registered only an 11% Sr in Păltiniș, while in the Rodna trial, the Sr was four times higher (in both trials, consanguineous trees were dominated). The juvenile–adult correlations of growth traits were significant, indicating that early selection could be efficient. The forward selection of the best 10% of CP families for Dbh could be applied, ensuring a 9% to 15% genetic gain.

Microsite preferences of three conifers in calcareous and siliceous treeline ecotones in the French alps

AbstractSeedling establishment is crucial for elevational advance of tree species above the treeline ecotone, but the characteristics and availability of safe sites for tree regeneration in alpine ecosystems are not well understood. To better understand the potential of treeline ecotones to show infilling or upward shifts, we assessed microsite preferences of the conifers Larix decidua, Pinus uncinata, and Pinus cembra in upper treeline ecotones with different bedrock chemistry in the French Alps. At each of two sites on calcareous and two on siliceous bedrock, we compared microsites of 50 tree individuals to 50 randomly-selected reference microsites, considering substrate, ground cover, topography, and shelter proximity. In addition, we related these characteristics with the health of the individuals. We found that the three species were established in similar microsites, usually with some shelter. The occupied microsites reflected the available microsites in the area, but certain extreme microsite types remained unoccupied. Most individuals had a krummholz form or were bent, while only a small proportion presented signs of recent mechanical damage, desiccation, snow mold or herbivory, independent of microsite characteristics. Our study shows that the availability of safe sites unlikely limits the establishment of these conifers in the studied sites, suggesting that, instead, seed availability may be a major limitation for tree establishment in these alpine-treeline ecotones. Even in safe sites, the harsh alpine conditions limit the development of tree-species individuals into tree stature, but the strong recent length growth observed suggests favorable conditions for eventual tree expansion in and above current treeline ecotones.

Snowmelt and subsurface heterogeneity control tree water sources in a subalpine forest

AbstractIn high mountain areas, snowmelt water is a key—yet fading—hydrological resource, but its importance for soil recharge and tree root water uptake is understudied. In these environments, heterogeneous terrains enhance a highly variable availability of soil and groundwater resources that can be accessed by plants. We conducted a tracer‐based study on a subalpine forest in the Italian Alps. We investigated the isotopic composition (2H and 18O) of snowmelt, precipitation, spring water, soil water—at different locations and depths—and xylem water of twigs taken from alpine larch, Swiss stone pine and alpenrose plants during bi‐weekly field campaigns (growing seasons of 2020 and 2021). Mixing models based on δ18O revealed a large contribution of snowmelt to soil and xylem water, particularly during early summer. We investigated the contribution of water from different soil depths to xylem water, using the sap flow records to date back the end‐member signatures. We found a flexible use of shallow and deeper soil water by the investigated plants, with groundwater more likely used by larger trees and during the late summer. Results based on isotopic data were combined with geophysical observations of the subsurface structure to develop a conceptual model about the different exploitation of water by plants depending on their location (shallow soil on a slope vs. a saturated area). Our study highlights the relevance of snowmelt in high‐elevation terrestrial ecosystems, where heterogeneous substrates shape the water availability at different depths and, in turn, water uptake by plants.

Temperature-induced germination pulses above the alpine tree line

ABSTRACT Subject to a long research tradition, the tree line is considered an important biogeographic indicator of climate changes and associated range shifts. Realized tree line positions and the potential tree line isotherm are, however, rarely in equilibrium because trees are unable to track rapid temperature variations. Often ignored in tree line research, this dilemma constrains the suitability of tree line trees for understanding alpine vegetation responses to anthropogenic warming. Here, we present combined dendrochronological and wood anatomical assessments of 1,351 seedlings and saplings from three subalpine forest species—larch (Larix decidua Mill.), pine (Pinus cembra L.), and spruce (Picea abies)—collected between ~2,200 and 2,600 m.a.s.l. in the Swiss Alps. We found evidence for temperature-induced, pulse-like seedling germination, rather than a continuous, long-term upward movement. Though the species spread across overlapping elevational ranges, larch was found at the highest elevations, followed by spruce and pine. Surprisingly, we found a varying age structure, with no sign of decreasing age toward higher elevations. Spring and summer temperatures promoted germination pulses, but postgermination survival was likely facilitated by species-specific plant traits. Our study demonstrates the importance of seedling and sapling data from above the tree line to understand prevailing vegetation dynamics at cold temperature extremes and also suggests future tree line advancement in the Swiss Alps.

Five decades of ecological and meteorological data enhance the mechanistic understanding of global change impacts on the treeline ecotone in the European Alps

Understanding the dynamics of treeline ecotones under global change requires long-term ecological and environmental data. The Stillberg ecological treeline research site in the Swiss Alps was established in 1975 by planting 92,000 seedlings of Larix decidua, Pinus cembra and Pinus mugo ssp. uncinata, and has been continuously monitored since then. Here, we present curated long-term data acquired over almost 50 years at the Stillberg site, and we synthesise the major research findings. The long-term datasets comprise 6.5 million ecological and environmental records from the 40-year afforestation experiment, as well as from a 9-year free-air CO2 enrichment experiment crossed with a 6-year soil warming experiment, a 12-year nutrient addition experiment and an 8-year multifactorial tree seedling recruitment experiment. Our datasets further include 38 million records of 25 meteorological parameters measured at an hourly resolution from 1975 to 1996, and at a 10 min resolution since 1997. We provide all datasets and the corresponding metadata as open research data. Almost five decades of research in this treeline ecotone showed high mortality after tree establishment that was closely related to microclimatic variability. The two Pinus species survived at a much lower rate than L. decidua, due to indirect pathogen interactions. Furthermore, CO2 enrichment only increased growth of L. decidua, while warming increased growth of P. mugo ssp. uncinata and two Vaccinium shrub species. Enhanced nutrient availability stimulated growth in tree and understorey shrub species. In addition, soil warming and CO2 enrichment stimulated microbial activity and decreased soil carbon stocks. These findings improve our understanding of ecological processes in the treeline ecotone under global change and confirm the importance of tree growth and establishment limitations. The enhanced availability and quality of these long-term data are expected to foster whole-system approaches and transdisciplinary research syntheses, supporting the development of effective global change adaptation strategies.

Rapid advance of climatic tree limits in the Eastern Alps explained by on-site temperatures

In the European Alps, mean temperature has risen by 2.5 K since the end of the nineteenth century. A 2 K warming of the growing season has taken place in the last 4 decades only. The 2.5 K warming should rise the position of the climatic treeline by about 400 m. Actual shifts in uppermost tree positions reported here for the Austrian Defereggen Valley and the Swiss Lower Engadine region of the Eastern Alps reach only around 140 m of elevation above the limit of old trees that date back to the nineteenth century. Uppermost Pinus cembra trees of > 2 m height currently occur at c. 2500 m, representing elevation records for the Eastern Alps. In situ temperature records for 2022–2023 revealed seasonal mean temperatures for uppermost trees that are 1–3 K higher than the equilibrium treeline isotherm of c. 6 °C in both regions (corrected for temperature anomalies from long-term records). The 2 K span reflects microhabitat differences and two ways to define the season. Thus, tree advances lag behind the upslope shift of the treeline isotherm, on average, by more than 200 m. The uppermost trees currently grow under quite warm conditions with annual shoot length increments frequently reaching 20 cm. Even without additional future warming, the new steady-state climatic treeline will exceed the Holocene maximum elevation in the Eastern Alps substantially.

Scenting serenity: influence of essential-oil vaporization on dental anxiety - a cluster-randomized, controlled, single-blinded study (AROMA_dent)

Dental fear and anxiety (DFA) is known as an immense challenge in oral healthcare, which can result in compromised oral health, pain, and uncomfortable treatment. The objective of this study was to analyze the effect of essential-oil vaporization on acute anxiety of patients in dental practices. Four dental practices used five weekly cycles of vaporization with each scent: Orange (Citrus sinensis), Swiss Pine (Pinus cembra), Good Mood (blended essential oils: Citrus sinensis, Citrus aurantifolia, Citrus limon, Osmanthus fragrance (5%)), Forest Walk (blended essential oils: Abies grandis, Pinus cembra, Myrtus communis c. t. 1,8-cineol, Abies alba, Citrus paradisi, Abies sibirica, Pseudotsuga menziesii, Vetiveria zizanoides), and water. Acute anxiety was the primary outcome (state-trait-anxiety inventory (STAI-S)). Secondary outcomes were trait anxiety (STAI-T), dental anxiety (Kleinknecht dental fear survey), and pain perception in treatment (numeric rating scale). Across all patients (n = 486), STAI-S was slightly higher in the control group (40.7 ± 11.6) than in the intervention groups (38.4 ± 10.5). Post-hoc analyses revealed that the effect is only robust for the subgroup of female patients (n = 296, p = 0.044). We also conducted a post-hoc additional analysis on a subpopulation with an increased level of STAI-T ≥ 42 (n = 131 patients). For this group the difference in acute anxiety between the control group (51.1 ± 11.9, n = 30) vs. the intervention groups (46.8 ± 9.6, n = 118) was significant (T = 4.39, p = 0.0379). The results of the study indicate a promising potential of essential-oil vaporization to alleviate dental anxiety, particularly in the subgroups of patients with a high level of trait anxiety, and particularly in female patients. The calming effects of the essential-oil vaporization were also highlighted by the anecdotical statements of the dental-practice staff. The anxiety-reducing role of essential-oil vaporization alone and as one part of combined techniques to counter DFA should be further explored using multi-perspective methodological approaches in research.

Multiproxy tree ring reconstruction of glacier mass balance: insights from Pinus cembra trees growing near Silvretta Glacier (Swiss Alps)

Abstract. Glacier mass balance reconstructions provide a means of placing relatively short observational records into a longer-term context. Here, we use multiple proxies from Pinus cembra trees from God da Tamangur, combining tree ring anatomy and stable isotope chronologies to reconstruct seasonal glacier mass balance (i.e., winter, summer, and annual mass balance) for the nearby Silvretta Glacier over the last 2 centuries. The combination of tree ring width, radial diameter of earlywood cell lumina, and latewood radial cell wall thickness provides a highly significant reconstruction for summer mass balance, whereas for the winter mass balance, the correlation was less significant but still robust when radial cell lumina were combined with δ18O records. A combination of the reconstructed winter and summer mass balances allows the quantification of the annual mass balance of the Silvretta Glacier for which in situ measurements date back to 1919. Our reconstruction indicates a substantial increase in glacier mass during the first half of the 19th century and an abrupt termination of this phase after the end of the Little Ice Age. Since the 1860s, negative glacier mass balances have been dominant and mass losses accelerate as anthropogenic warming picks up in the Alps.

Fungal and bacterial communities and their associations in snow-free and snow covered (sub-)alpine Pinus cembra forest soils

BackgroundIn Europe, Pinus cembra forests cover subalpine and alpine areas and they are of high conservational and ecological relevance. These forests experience strong seasonality with alternating snow-free and snow covered periods. Although P. cembra is known for mycorrhization and mycorrhizae usually involve fungi, plants and bacteria, the community compositions of fungi and bacteria and their associations in (sub-)alpine P. cembra forests remain vastly understudied. Here, we studied the fungal and bacterial community compositions in three independent (sub-)alpine P. cembra forests and inferred their microbial associations using marker gene sequencing and network analysis. We asked about the effect of snow cover on microbial compositions and associations. In addition, we propose inferring microbial associations across a range of filtering criteria, based on which we infer well justified, concrete microbial associations with high potential for ecological relevance that are typical for P. cembra forests and depending on snow cover.ResultsThe overall fungal and bacterial community structure was comparable with regards to both forest locations and snow cover. However, occurrence, abundance, and diversity patterns of several microbial taxa typical for P. cembra forests differed among snow-free and snow covered soils, e.g. Russula, Tetracladium and Phenoliphera. Moreover, network properties and microbial associations were influenced by snow cover. Here, we present concrete microbial associations on genus and species level that were repeatedly found across microbial networks, thereby confirming their ecological relevance. Most importantly, ectomycorrhizal fungi, such as Basidioascus, Pseudotomentella and Rhizopogon, as well as saprobic Mortierella changed their bacterial association partners depending on snow cover.ConclusionThis is the first study researching fungal-bacterial associations across several (sub-)alpine P. cembra forests. The poorly investigated influence of snow cover on soil fungi and bacteria, especially those mycorrhizing P. cembra roots, but also saprobic soil organisms, underlines the relevance of forest seasonality. Our findings highlight that the seasonal impact of snow cover has significant consequences for the ecology of the ecosystem, particularly in relation to mycorrhization and nutrient cycling. It is imperative to consider such effects for a comprehensive understanding of the functioning resilience and responsiveness of an ecosystem.

A systematic review of studies on fine and coarse root traits measurement: towards the enhancement of urban forests monitoring and management

The analysis of fine and coarse roots’ functional traits has the potential to reveal the performance of the root system, which is pivotal in tree growth, development, and failure in both natural and urban forest ecosystems. Furthermore, root traits may be a powerful indicator of tree resilience mechanisms. However, due to the inherent difficulties in measuring ‘the hidden half,’ and despite the recent advancements, the relationships among root functional traits and biotic and abiotic drivers still suffer from a lack of information. Thus, our study aimed to evidence knowledge milestones and gaps and to categorize, discuss, and suggest future directions for effective experimental designs in fine and coarse root studies. To this end, we conducted a systematic literature review supported by backward manual referencing based on 55 root functional traits and 136 plant species potentially suitable for afforestation and reforestation of natural and urban forest ecosystems. The majority of the 168 papers on fine and coarse root studies selected in our review focused predominantly on European natural contexts for a few plant species, such as Fagus sylvatica, Picea abies, Pinus sylvestris, and Pinus cembra, and root functional traits such as standing biomass, phenology production, turnover rate, and non-structural carbohydrates (NSC). Additionally, the analyzed studies frequently lack information and uniformity in experimental designs, measurements, and statistical analysis, highlighting the difficult integration and comparison of outcomes derived from different experiments and sites. Moreover, no information has been detected in selected literature about urban forest ecosystems, while most of the studies focus on natural forests. These biases observed during our literature analysis led us to give key indications for future experiment designs with fine and coarse roots involved, which may contribute to the building up of common protocols to boost the monitoring, managing, and planning of afforestation and reforestation projects.

Ecological preferences of the Swiss pine (Pinus cembra L.) forests in the Gorgany Nature Reserve

Swiss pine (Pinus cembra L.) is a montane Carpathian (Alpine-Carpathian) species. The modern distribution of the Swiss pine is disjunct, the two isolated areas are located in western and central Europe (Alps) and the middle and high mountains of the Carpathians. The largest areas of Swiss pine in Ukraine are preserved in the Gorgany region at the altitude of 1250‒1450 m above sea level, where it forms the upper forest line. In the Gorgany Nature Reserve, P. cembra grows in the altitude range from 1070 to 1475 m ASL. The lower boundary, in the form of individual trees, descends to 1000 m ASL, and the upper boundary rises to 1585 m ASL. To define the ecological preferences of the Swiss pine, a series of route surveys were conducted and research sites (permanent forest monitoring plots, stationary research profiles, and stationary areas for the counting of natural forest regeneration) were established. The study of the plant communities with P. cembra on the southwestern slopes of the Dzhurdzhi tract showed the dependence of the forest species composition on the altitude above sea level. The forest stands quantitative composition and productivity are also significantly influenced by slope exposure. The proportion of P. cembra in the forests on steep slopes (30‒55°) of west and north-west exposure is relatively high (from 17.1% to 49.0%). Under other conditions, the proportion of P. cembra in the stand composition gradually decreases. Swiss pine is almost completely absent on the slopes of eastern and northern exposures except for rare single trees in Pinus mugo Turra scrub on northern slopes. The forests with P. cembra are typical of sunny slopes where the available sum of active temperatures ranges between 1000° and 1400° and the average ambient temperatures from -12.2°С to +16°С. The optimal environmental conditions for the relict species P. cembra in the Dovbushanski Gorgany region are on the western slopes with a steepness of 17‒55° and southwestern and northwestern slopes with a steepness of 35°‒42°. In terms of soil fertility, oligotrophic edaphotopes with moderate moisture are optimal for the growth of Swiss pine.

Genetic underpinning of historical afforestation with allochthonous Pinus cembra in the northwestern Swiss Alps

AbstractThroughout the last centuries, the structure and genetic composition of forests have been strongly affected by forest management. Over 30% of European forests are artificially regenerated, very often using translocated forest reproductive material, among these species the Swiss stone pine (Pinus cembra L.). In the late nineteenth and early twentieth centuries, the species was largely used for artificial afforestation in the northern Alps. However, only a few planted trees have survived. Therefore, we aimed to evaluate if the historical afforestation of P. cembra in the northwestern Swiss Alps relied on allochthonous material. We sampled 12 sites, genotyping 11 nuclear microsatellites, to infer the spatial genetic structure of regional populations, to test for genetic differences between natural and planted stands, and to infer potential source regions of planted stands using reference samples covering the entire Alps. Population genetic structure analysis allowed us to distinguish planted from natural stands and to determine that forest reproductive material used for plantations was not of regional origin. We found similar levels of genetic diversity between natural and planted stands. Assignment tests revealed that reproductive material for planting was translocated to the study area from two source regions, i.e., near the border of Switzerland and Austria, and further to the East, between Austria and Italy. Our study shows how genetic tools may inform about historical transfer of forest reproductive material, which still may affect the population genetic make-up of regional occurrences, e.g., because of reduced natural regeneration.

Some wood-inhabiting Basidiomycota from the primeval forests with Pinus cembra in Ukraine

The Pinus cembra communities belong to the rarest and least studied woody habitats in Europe. This article reports 30 species of lignicolous Basidiomycota revealed in primeval spruce stands with the admixture of arolla pine in Gorgany Nature Reserve (the Ukrainian Carpathians). Five species, namely Aphanobasidium subnitens, Ceraceomyces eludens, Hyphoderma occidentale, Hypochnicium albostramineum and H. cremicolor, are firstly reported in Ukraine. The records of Cystostereum murrayi, Phellinus viticola and Pycnoporellus fulgens deserve particular attention due to their value as bioindicators of natural forest ecosystems. The species composition of Basidiomycota per individual fallen log turned out to be rather poor. The fungi forming thin resupinate corticioid basidiocarps on the substrate underside prevail among the finds, indicating a lack of moisture in the surveyed treeline stands. Detailed descriptions of the substrate and collection site are given for each find. An overview of previous research on the diversity of lignicolous Basidiomycota in arolla pine forests is provided.

Palaeoecological multiproxy reconstruction captures long-term climatic and anthropogenic impacts on vegetation dynamics in the Rhaetian Alps

Alpine ecosystems are particularly affected by climate change due to their high sensitivity to temperature variations. Understanding the response of vegetation to rapid temperature increase and human impact is necessary to produce accurate and reliable predictions of future mountain vegetation and mitigate climate change impacts. Our multiproxy study reconstructs climate, fire, and vegetation dynamics over the last 14,200 cal. BP at Lai da Vons (1991 m a.s.l.), a subalpine lake situated in the treeline ecotone in Eastern Switzerland. Our results based on geochemical analysis (XRF), pollen and charcoal analysis, and high-resolution macrofossil analysis reveal that early afforestation started already at the onset of the Holocene, dominated by Pinus cembra and Larix decidua. Larch and stone pine formed closed forests at the site at 10,300 cal. BP. From 9500 cal. BP onwards, when summer temperatures were warmer than today, Picea abies expanded simultaneously with Abies alba. In the past 6500 years, increasing human impact, culminating during two main phases of landscape opening and intensification of fire regime, led to a progressive increase of species richness. Considering future climate change, an upward shift of treeline and timberline is expected in the absence of domesticated herbivores. We advocate that low-intensity pastoralism in such a cultural landscape is essential to preserve the plant diversity of species-rich mountain meadows.

Climate response of a glacial relict conifer across its distribution range is invariant in space but not in time

Climate change impacts on forest trees will be particularly severe for relict species endemic to the subalpine forest, such as Pinus cembra in the Alps and Carpathians. Most current knowledge about the response of this species to climate comes from tree-ring width analysis. However, this approach cannot perform in-depth and highly time-resolved analysis on the climate influence on specific growth processes and xylem functions. We analyzed xylem anatomical traits from six sites covering most of the longitudinal range of this species. Associations between climate and cell number, lumen area and cell wall thickness were computed for the 1920–2010 period using climate records aligned to degree-day temperature sum thresholds. The anatomical chronologies were clearly distinct between the Alps and Carpathians. However, climate responses were similar for all sites, suggesting common species-specific response mechanisms. Temperature showed a positive correlation with both cell number and cell wall thickness. Cell lumen size exhibited an early positive association, followed by strong negative association with temperature and a positive one with precipitation. This highlights that the cell enlargement process was negatively related to high temperature at high elevation, where meristematic processes are rather supposed to be constrained by low temperatures. Therefore, long-term climate warming can have negative consequences on the xylem potential to transport water at all investigated sites. Moreover, in the last 30 years, we observed a slight anticipation of some responses and a decrease in climate sensitivity of some xylem parameters. Our findings provide evidence of temporally unstable but spatially consistent climate response of Pinus cembra from the Alps to the Carpathians. The low diversity in xylem phenotypic responses to climate suggests that future warming could extensively and evenly affect the species throughout its entire distribution.

Phytochemical Analysis of Pinus cembra Heartwood-UHPLC-DAD-ESI-MSn with Focus on Flavonoids, Stilbenes, Bibenzyls and Improved HPLC Separation.

The heartwood of the Swiss Stone Pine, Pinus cembra L., has been scarcely investigated for secondary metabolites for a long period of time. Considering age and relative simplicity of heartwood investigations dating back to the 1940s to 1960s, we conducted the first investigation of P. cembra heartwood by HPLC, using UHPLC-DAD-ESI-MSn and HPLC-DAD techniques in combination with isolation and NMR spectroscopy, with focus on stilbenes, bibenzyls and flavonoids. Analytical problems in the HPLC analysis of Pinus stilbenes and flavonoids on reversed stationary phases were also challenged, by comparing HPLC on pentafluorophenyl (PFP) and C18 stationary phases. Seven flavonoids (1, 2, 3, 7, 8, 11, 12), four stilbenes (4, 6, 10, 13), two bibenzyls (5, 9), three fatty acids (14, 16, 17) and one diterpenic acid (15) were detected in an ethanolic extract of Pinus cembra heartwood. HPLC comparison of reversed stationary phases in HPLC showed that the antifungal, antibacterial and chemosensitizing dihydropinosylvin monomethyl ether (9) and pinosylvin monomethyl ether (10) can be separated on PFP, but not on C18 material, when eluting with a screening gradient of 20-100% acetonitrile. Flavonoid separation showed additional benefits of combining analyses on different stationary phases, as flavonoids 7 and 8 could only be separated on one of two C18 stationary phases. Earlier phytochemical results for heartwood investigations were shown to be mostly correct, yet expandable. Substances 5 to 12 were found in alignment with these references, proving remarkable phytochemical analyses at the time. Evidence for the described presence of pinobanksin could not be found. Substances 1 to 4 and 13 have to our knowledge not yet been described for P. cembra.

The Influence of Ecological Factors on the Phytochemical Characteristics of Pinus cembra L.

Pinus cembra L., also known as Swiss pine, is one of the lesser studied coniferous species, despite literature pointing out its great potential to be used for medical purposes due to its high contents in active phytochemicals. The aim of this study is to phytochemically assess rhytidome and periderm extracts obtained from Swiss pine from various locations and altitudes, so as to be able to deduce the best locations for harvesting samples with the highest biological activity. After the plant was analyzed histo-anatomically, hydroalcoholic extracts were obtained using ultrasounds, a rotary evaporator, and dry freezing. After determining the total polyphenolic content (TPC) in each sample, they were tested for antioxidant and enzymatic activity, while taking note of the influence of the varying altitudes and different harvesting regions on the intensity of each activity. The results from the TPC analysis show that rhytidome samples collected from the highest altitude (2429 m) displayed the highest content of polyphenols, with a general tendency for the amount of polyphenolic content to be directly correlated to altitude, this finding being further supported by the antioxidant activity also growing directly proportionally with the altitude. Enzymatic inhibition activity was found to be moderate for α-glucosidase and low for α-amylase. Following our findings, we can safely say that Pinus cembra L. extracts can be a great source of compounds with antioxidant activity; however, further studies are warranted to best determine the true potential of this species.

Unsuspected prevalence of Pinus cembra in the high-elevation sky islands of the western Alps

Unsuspected prevalence of Pinus cembra in the high-elevation sky islands of the western Alps