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.
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•We investigated Pinus cembra xylem anatomy at 6 sites in the Alps and Carpathians.•Climate responses were consistent across sites, but varied over the study period.•At all sites, we observed negative effect of high temperature on cell lumen area.•Climate warming can harm xylem hydraulic system of P. cembra in its entire range.
•Planting methods are crucial in shaping the C/N/P stoichiometry of soils and plants.•C/N/P stoichiometry is proven to be useful for reflecting the nutrient cycle.•N and P deficiencies are a limiting ...factor for plant growth in the mountains.•Enzyme activity proved to be useful for assessing the effect of various planting.•Extracellular enzyme stoichiometry is indicator of the nutrient availability.
C/N/P stoichiometry offers important indicators of ecosystem function and productivity. The aim of this research was to determine how planting methods in biogroups influence C/N/P stoichiometry in soil and plants. We hypothesised that planting methods, consisting in different initial spacing and shape would affect the growth characteristics of trees, and consequently, change soil properties – microbiological activity, in particular. This research examined two species that have different ecological requirements, silver fir (Abies alba Mill.) and Swiss stone pine (Pinus cembra L.), grown in the upper mountain zone, 1200 m above sea level. We established 48 experimental plots with two planting methods and two species in 2011. The soil and plant samples for laboratory analysis were taken in September 2020. In the first planting method 49 seedlings at regular 1 × 1 m spacing in a square plot (PM1) were planted, while in the second method 50 seedlings in two rhombus plots with 50 × 50 cm spacing (PM2) were planted. We determined the basic physicochemical properties and enzymatic activity in soil samples, and we recorded the content of C, N and P in testing needle samples from the trees. We also calculated the C/N, C/P and N/P ratios for both the soil samples and the plants. We found that the formation of biogroups with smaller spacing during stand renewal influenced the selected soil properties; within the biogroups with smaller spacing, an increase in soil biochemical activity was found. Our research confirms that planting methods and species are essential contributors to the C/N/P stoichiometry of soils and plants. The C/N/P stoichiometry of the soil samples from the different species and the different planting methods ranged between 928/37/1 and 1087/42/1. In the case of the Swiss stone pine needles, we noted a narrower C/N/P stoichiometry compared to the fir needles, regardless of the planting method. C/N/P stoichiometry is a useful tool for reflecting the nutrient cycle in mountain ecosystems, and our research shows that in the case of species with higher ecological requirements, stoichiometry can indicate nutrient limitation. In higher mountainous locations, nitrogen and phosphorus deficiencies are the main limiting factor. In the case of fir trees, the method of planting helps to reduce nutrient limitation and improve growth characteristics.
We analyse annually resolved tree‐ring stable carbon (δ13C) and oxygen (δ18O) isotopic chronologies from Swiss stone pine (Pinus cembra L.) in Romania. The chronologies cover the period between 1876 ...and 2012 and integrate data from four individual trees from the Calimani Mts in the eastern Carpathians where climatic records are scarce and starts only from 1961. Calibration trials show that the δ13C values correlate with local April–May relative humidity and with regional to larger scale (European) summer precipitation. δ18O correlates significantly with local relative humidity, cloud cover, maximum temperature, as well as European scale drought conditions. In all cases, the climate effects on δ13C values are weaker than those recorded in the δ18O data, with the latter revealing a tendency toward higher (lower) values of δ18O during extremely dry (wet) years. The most striking signal, however, is the strong link between the interannual δ18O variability recorded in the Calimani Mts and large‐scale circulation patterns associated with North Atlantic and Mediteraneean Sea sea surface temperatures. High (low) values of δ18O occur in association with a high (low) pressure system over the central and eastern part of Europe and with a significantly warmer (colder) Mediterranean Sea surface temperature. These results demonstrate the possibility of using tree ring oxygen isotopes from the eastern Carpathians to reconstruct regional drought conditions in eastern Europe on long‐term time scales and larger scale circulation dynamics over the preinstrumental periods.
Our results demonstrate the possibility of using tree ring oxygen isotopes from the eastern Carpathians to reconstruct regional drought conditions in eastern Europe on long‐term time scales and larger scale circulation dynamics over the preinstrumental periods. The composite map between high δ18O (> 1 SD) and summer sea surface temperature (SST). The hatching highlights significant values at a confidence level of 95%. Analysed period: 1876–2012.
Natural subalpine forests are considered to be sensitive to climate change, and forest characteristics are assumed to reflect the prevalent disturbance regime. We hypothesize that stand history ...determines different stand structures. Based on large full inventory datasets (including tree biometric data, spatial coordinates, tree age, and basal area increment) we assessed the size structure, tree recruitment dynamics and radial growth patterns in three permanent plots along an altitudinal gradient in a mixed coniferous forest (Picea abies and Pinus cembra) in the Eastern Carpathians. Both discrete disturbances (large scale or small scale) and chronic disturbances (climate change) were identified as drivers of stand structure development in the studied plots. A stand replacing wind disturbance generated a unimodal bell-shaped size and age distribution for both species characterized by a sharp increase in post-disturbance recruitment. By contrast, small-scale wind-caused gaps led to a negative exponential diameter distribution for spruce and a left-asymmetric unimodal for pine. Climate-driven infilling processes in the upper subalpine forest were reflected as J-shaped size and age distributions for both species, but with pine predating spruce. The growth patterns for both species demonstrated an increased basal area increment since the early 1900s, with an emphasis in the last few decades, irrespective of stand history. Pine demonstrated a competitive advantage compared to spruce due to the higher growth rate and size at the same age. Recognition of combined discrete and chronic disturbances as drivers of the tree layer characteristics in a subalpine coniferous forest is essential in both stand history analyses and growth predictions.
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•Different stand history induce different stand size and age structure.•Both large-scale and small-scale episodic disturbance and climate change structure mixed coniferous subalpine forests.•Basal area increment for spruce and pine from subalpine forest has accelerated in last decades.
Ongoing climate change strongly affects high-elevation environments in the European Alps, influencing the cryosphere and the biosphere and causing widespread retreat of glaciers and changes in ...biomes. Nevertheless, high-elevation areas often lack long meteorological series, and global datasets cannot represent local variations well. Thus, proxy data, such as tree rings, provide information on past climatic variations from these remote sites. Although maximum latewood density (MXD) chronologies provide better temperature information than those based on tree-ring width (TRW), MXD series from the European Alps are lacking. To derive high-quality temperature information for the Rhaetian Alps, Pinus cembra L. trees sampled at approximately 2000 m a.s.l. were used to build one MXD chronology spanning from 1647 to 2015. The MXD data were significantly and highly correlated with seasonal May-September mean temperatures. The MXD chronology showed a generally positive trend since the middle of the 19th century, interrupted by short phases of climatic deterioration in the beginning of the 20th century and in the 1970s, conforming with the temperature trends. Our results underline the potential for using Pinus cembra L. MXD to reconstruct mean temperature variations, especially during the onset and latter part of the growing season, providing additional information on parts of the growing season not inferred from TRW. Future studies on MXD for this species will increase the availability of temporal and spatial data, allowing detailed climate reconstructions.
1. Fungi are both agents of disease and mutualistic partners of plants. Previous studies have tested the effects of abiotic or biotic factors on plant-associated fungal communities in isolation. ...However, to better understand patterns of plant-fungal associations, the combined effects of abiotic and biotic drivers across environmental gradients may be important. 2. We investigated the effects of temperature, pH, soil moisture, vegetation cover and distance to host plant on the occurrence and abundance of fungi associated with Swiss stone pine (Pinus cembra). We did this by DNA metabarcoding 288 soil samples taken across and beyond the elevation range of P. cembra (i.e. 1,8502,250 m a.s.l.) in two valleys in the Swiss Alps. We modelled the effects of abiotic and biotic factors on DNA read abundance of pathogenic and mutualistic fungal operational taxonomic units (OTUs) associated with P. cembra. We also tested whether abiotic and biotic factors differentially affected fungi of varying host specificity (i.e. host generalists, host specialists). 3. We found that the occurrences of both host generalist and specialist fungi exceeded the current elevational range of their host plant. Abiotic factors had only minor effects on the abundances of all fungal OTUs. However, we found positive effects of the host plant on the abundance of a host specialist pathogenic fungus, providing support for a Janzen-Connell effect of high pathogen accumulation close to conspecific host plants. We also found a positive response to the host plant in a specialist ectomycorrhizal fungus, suggesting an "inverse" JanzenConnell effect. 4. Synthesis. Our findings imply that negative distance dependence shapes not only the distribution of host-specific fungal pathogens, but also host-specific fungal mutualists. We conclude that the occurrence of both pathogenic and mutualistic fungi beyond the current elevational range of host plants may determine their potential range shifts under projected climate warming.
Between the nineteenth and early twentieth centuries, large-scale afforestation projects were undertaken in the Swiss Prealps. The Swiss stone pine (
Pinus cembra
L.), an emblematic alpine tree with ...important economic potential, conservation value and ecological relevance, was one of the species used in these afforestation efforts. We investigated the distribution and site characteristics of all known natural populations and planted stands in the canton of Fribourg (Switzerland). Between 1885 and 1952, artificial afforestation was carried out in the mountainous regions of the canton of Fribourg. Nearly 450,000 seedlings of
P. cembra
were planted. One century later, only approximately 650 trees survived (0.15% of all planted trees). Moreover, no natural regeneration can be observed in the afforested stands. Since no known harvest activities were undertaken in these planted stands, the whole afforestation campaign of
P. cembra
in the canton of Fribourg can be described as a failure. Possible causes are investigated and discussed. In this region,
P. cembra
occurs naturally only in particular microrefugia with markedly rough topography. We argue that the lack of knowledge or consideration of the ecology of the species at a local scale can be an important factor leading to this failure. In the actual context of large-scale afforestation projects anticipating and mitigating the negative effects of global warming, our study highlights the importance of a precise understanding of species ecology and regional conditions.
Throughout 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.
Current distributions of Swiss stone pine mostly cover the mountain regions of Europe (Alps and Carpathians). Easternmost distribution of this species is located in western Ukraine. Due to ...environmental fragmentation in Eastern Carpathians and competition with Norway spruce and other species, marginal populations of Swiss stone pine create isolated island, where other species are not able to cope with harsh conditions. Still,
L. play an important role for soil-formation and soil-protection in high elevations. The evidence of recent reduction in the area of Swiss stone pine raises the question whether the introduction of this species at lower altitudes can be successful? According to the studies conducted on reciprocal transplant experiments, Swiss stone pine population from higher elevation are able to profit in low elevation sites. Thus, parallelly with gene conservation activity, the possibilities of assisted migration should be recognized for this species.
The essential oils from needles, twigs, bark, wood, and cones of Pinus cembra were analyzed by GC‐FID, GC/MS, and 1H‐NMR spectroscopy. More than 130 compounds were identified. The oils differed in ...the quantitative composition. The principal components of the oil from twigs with needles were α‐pinene (36.3%), limonene (22.7%) and β‐phellandrene (12.0%). The needle oil was dominated by α‐pinene (48.4%), whereas in the oil from bark and in the oil from twigs without needles there were limonene (36.2% and 33.6%, resp.) and β‐phellandrene (18.8% and 17.1%, resp.). The main constituents of the wood oil as well as cone oil were α‐pinene (35.2% and 39.0%, resp.) and β‐pinene (10.4% and 18.9%, resp.). The wood oil and the cone oil contained large amounts of oxygenated diterpenes in comparison with needle, twig, and bark oils.
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