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Abstract: Precise dating of the year of felling is one intended outcome of dendrochronology. However, occasionally some or all sapwood rings might be missing, either due to deterioration or because they were carved off, or for some other reason. Consequently, while heartwood is preserved, sapwood might be fully or partially missing. In such cases, the year of felling must be estimated by adding a suitable number of sapwood rings. A heartwood age rule (HAR) has been advocated for Scots pine and adapted to European larch and Cembra pine, implying a linear relationship between sapwood ring count and the square root of heartwood ring count, largely irrespective of position in the stem. The same rule applied to all observations of a species, irrespective of silviculture, location or fertility of the growth site. Scots pine had twice or thrice as many sapwood rings as Cembra pine, which had 10% more rings than larch. The magnitude of model residuals was proportional to estimated sapwood ring count. Relative residuals were roughly normally distributed. To be applicable in Bayesian modelling in dendrochronology analyses, detailed information on model errors has been provided. [Copyright &y& Elsevier]

Highlights: [•] Regeneration dynamics is a key factor in shaping high-altitude forests. [•] We used spatial statistics in three fully-mapped 1-ha plots on an elevation gradient in the Alps. [•] The spatial pattern of regeneration is surprising convergent among sites. [•] These similarities come out despite the species and stand features differences. [Copyright &y& Elsevier]

The article presents a study on the diversity pattern of Swiss stone pine, Pinus cembra L. along the Carpathian range. The range characteristics of nine Swiss stone pine populations were analyzed using six chloroplast DNA microsatellites (cpSSR). The study revealed that the most diverse populations can be found in the Retezat Mountains in South Carpathians and the High Tatras, while the diversity of population decreases towards Eastern Carpathian.

The article offers information on the investigation of characteristics of Swiss stone pine along the Carpathian Mountains range including the High Tatras, by using six chloroplast DNA microsatellites (cpSSR). It mentions the aim of an investigation as geographical range to detect genetically distinct regions by clustering of populations and also highlights restriction to the timberline ecotones with spruce larch (Larix decidua) or mountain pine (Pinus mugo.

Abstract: Proactive management should be applied within a forest conservation context to prevent extinction or degradation of those forest ecosystems that we suspect will be affected by global warming in the next century. The aim of this study is to estimate the vulnerability under climate change of a localized and endemic tree species Pinus cembra that occurs in the alpine timberline. We used the Random Forest ensemble classifier and available bioclimatic and ecological data to model present and future suitable areas for P. cembra and estimate its current and future vulnerability. Future projections for years 2020, 2050 and 2080 were simulated using two IPCC Special Report on Emission Scenarios run under four global climate models. The suitability model described the optimal environmental conditions for P. cembra. Model scores (κ =0.77, sensitivity=0.99 and specificity=0.80) are robust. The main factors defining the model were Kira''s warmth index and summer temperatures. Results show that there is potential for P. cembra to regenerate and persist in currently suitable areas. Future trends analysis suggested a cumulated mean loss of suitable areas of between 53% and 72% for different scenarios. All modeled projections predicted an upslope shift of the optimally suitable P. cembra belt and no downslope shift. We discuss environmental factors/plant interactions, the theoretical assumptions behind the model, model strengths and limitations, and we highlight the conservative traits of our analysis. The results suggest that forest management practices will play a fundamental role in the conservation of P. cembra habitats in the Alps. [Copyright &y& Elsevier]

Abstract: This paper presents a new method for the standardisation of tree-ring series, which attempts to remove the age effect from the low-frequency variations in the series. standardisation techniques based on the biological growth trend (RCS) only remove the trend linked to the age of the tree. However, in some trees, the trend is substantially different from the regional curve, and when the site fertility is not taken into account, the standardisation process may induce significant biases in the RCS standardised curve. An artificial neural network is used here to estimate an adaptive regional growth curve (ARGC) model. For each population or group of populations, the predictors are, in addition to the age (used by RCS) of each ring, the initial and the maximum growth rates (measured by the ring increments) of each tree. We have compared this method to the RCS method, using 20 Pinus cembra sites covering the Southern French Alps. The results show that the ARGC standardisation performs better for growth trend analysis and, by inference, for climate reconstruction. [Copyright &y& Elsevier]

Abstract: A potential limitation of tree-ring based climate reconstructions is related to climate signal age effects (CSAE). CSAE may arise if the climatic response of young tree-rings differs from that of old tree-rings. This could mean that climatic signals become stronger (or weaker) with tree aging, or that the seasonality of signals or the sensitivity to a specific element (e.g., temperature, precipitation) changes over time. Such changes would affect the interpretation of dendroclimatic reconstructions, as the tree-rings included in these records are generally oldest at the end of a record (e.g., 21st century)—which is the time period generally used for calibration with instrumental data. We here addressed this concern by analyzing young and old Pinus cembra trees from three high elevation sites in the central European Alps. Core and disc samples were collected in pre-defined plots to allow for a representative analysis of tree ages with tree-ring width (TRW) measurement series categorized into age classes (i) >1880, (ii) 1880–1939, and (iii) 1940–2002. Notably we report on the signal of the very young category (iii) not yet described in literature, and thus allow estimation of climate response and signal strength characteristics during the first years of the trees’ lifespans. Comparison of age classes (i)–(iii) revealed differences in TRW coherence and size, but little change in climatic signal. CSAE are in the order of the differences recorded among high elevation sites—a conclusion that holds for inter-annual to decadal scale TRW variations at near-treeline Swiss stone pine. Such data are typically included in regional and larger-scale temperature reconstructions; thus, our results add confidence to long-term climate estimates integrating a range of tree-ring age classes. Other findings, such as the reaction wood in juvenile tree-rings, and sensitivity of the climate signal to sample replication, suggest that comparisons of young and old age classes, and separate calibration of these categories against instrumental climate data might further the estimation of long-term uncertainty changes in tree-ring based climate reconstructions. [Copyright &y& Elsevier]

Abstract: We summarize what is known about the impact of ozone (O3) on Pinus cembra in the timberline ecotone of the central European Alps and the Carpathian Mountains. In the central European Alps exposure to ambient and two-fold ambient O3 throughout one growing season did neither cause any visible injury nor affect the photosynthetic machinery and biochemical parameters in current to 1-year-old needles. By contrast, in the southern French Alps and in the Carpathians 1-year-old needles of Pinus cembra trees showed visual symptoms similar to those observed in O3 stressed pine stands in southern California. For the southern French Alps the observed symptoms could clearly be attributed O3 and differences in O3 uptake seems to be the likely key factor for explaining the observed decline. For the Carpathians however, other reasons such as drought may not be excluded in eliciting the observed symptoms. Thus, the action of O3 has always to be evaluated in concert with other environmental impacts, determining the tree''s sensitivity to stress. [Copyright &y& Elsevier]

Abstract: During the last centuries forest management has changed the structure and species composition of central European forests. One option to assess forest management and how management impacts may affect forest development over time is the use of biogeochemical ecosystem simulation models. They integrate key ecosystem processes and have proven to be an appropriate diagnostic tool. If we consider that in the past, forest management has strongly affected the species distribution and the structure of central European forests, existing biogeochemical models need to integrate species-specific parameters so that they can adequately address forest management practices such as species changes, stand density etc. The purpose of this paper is to introduce species-specific parameters for one such model, Biome-BGC, for the following tree species as observed in central European forests: Fagus sylvatica, Quercus robur/petraea, Larix decidua, Pinus sylvestris, Pinus cembra as well as two sets of parameters for Picea abies growing at low and high elevations. We first evaluate and test model results obtained with parameters from the literature and single research plots. This evaluation procedure gives our final species-specific parameters that are then used in the model. Next we validate the quality of the model predictions using these parameters versus field observations covering the growing range of a given species by comparing standing tree volume, volume increment, soil carbon and soil nitrogen on 145 independent plots. Our results demonstrate that the species-specific parameters yielded consistent and unbiased predictions. [Copyright &y& Elsevier]

Summary: To assess daily relationships between xylem development and the environment, precise knowledge of tree-ring development is required. This includes accurate estimations of the rate and duration of the cell enlargement and wall thickening phases. This paper presents an application where the Gompertz equation is used to calculate cell number increase and to estimate both the rates and periods of the differentiation phases on a daily scale during the growing season. Tests were performed on two coniferous species, Abies balsamea (L.) Mill. and Pinus cembra L., growing in the Canadian boreal forest and on the Italian Alpine treeline respectively. Wood micro-cores, including the most recent tree-rings, were collected during the growing season of 2001. Cross-sections were cut with a microtome and stained with cresyl fast violet to differentiate xylem cells of the growing tree-ring. The number of cells within the zones of radial cell enlargement, secondary wall thickening and mature xylem were counted. The normalised cell number increases were fitted into a Gompertz function [y=f(t)]. The results showed that the function provided suitable descriptions of the cell increase for both Abies balsamea and Pinus cembra with R2 ranging between 0.60 and 0.90. Subsequently, to assess the development phases in time, the Gompertz equation was expressed in function of the independent variable [t=f(y)]. The use of only one equation for the estimation of both cell division and differentiation throughout the vegetative season has demonstrated to be an important improvement. [Copyright &y& Elsevier]

The chemistry of fine roots of conifers of five subalpine forest stands in Switzerland was measured and related to soil pH. In addition, starch concentrations and ‘vitality’ (dehydrogenase activity) of the fine roots were measured in order to relate them to the soil pH, to the fine root chemistry, and to the fine root Ca/Al molar ratio. In fine roots from mineral soils, significantly positive correlations between fine root elements and the soil pH occurred for Ca and Mg, as well as for the Ca/Al molar ratio, while significantly negative correlations occurred for the micronutrients and the heavy metals, in particular for Cu and Pb. In fine roots from the organic layer, most of the fine root elements were not or only weakly correlated with the pH, as well as the Ca/Al molar ratio. Fine root starch concentrations were highly significant positive correlated with the fine root elements Al, Fe, and Mo, whereas the fine root ‘vitality’ was it with P and K. The correlations between the fine root Ca/Al molar ratio and the fine root starch concentration or the ‘vitality’ were not significantly positive but negative correlated, suggesting that these two fine root parameters are not suitable as physiological indicators for fine root Ca/Al molar ratios or for possible fine root damage resulting from Al stress. [Copyright &y& Elsevier]

Ozone (O3) flux into Norway spruce (Picea abies) and cembran pine (Pinus cembra) needles was estimated under ambient conditions at six rural sites between 580 and 1950 m a.s.l. We also assessed age-related differences in O3 flux by examining changes in leaf conductance across the life span of Norway spruce. At the leaf level O3 flux into the needles was effectively controlled by stomatal conductance and, hence by factors such as temperature, irradiance and humidity, which control stomatal conductance. Seasonal variations in O3 flux were mainly attributed to the course of the prevailing temperature. During the growing season, however, data have emphasized leaf-air vapour pressure difference as the environmental factor most likely to control stomatal conductance and O3 flux into the needles. In the sun crown stomatal conductance averaged over the growing season decreased with increasing tree age from 42.0+/-3.5 mmol O3 m-2 s-1 in 17-year-old trees to 7.1+/-1.0 mmol O3 m-2 s-1 in 216-year-old trees, indicating that O3 concentration in the substomatal cavities is higher in young than in old trees. Independent from tree age stomatal conductance and O3 flux were approximately 50% lower in shade needles as compared to sun-exposed needles. Stomatal conductance was also greater in the current flush (24+/-5.6 mmol O3 m-2 s-1) and in 1-year old needles (16+/-4 mmol O3 m-2 s-1)than in older needle age classes (12+/-1 mmol O3 m-2 s-1, averaged across the four older needle age classes). In trees similar in age (60-65 years old) average O3flux into sun needles increased from 0.5510.36 nmol m-2 s-1 at the valley floor to 0.9 nmol m-2 s-1 in 1950 m a.s.l. Cumulative O3 uptake during the vege [ABSTRACT FROM AUTHOR]