Tree Increment Research Articles

DEBLJINSKI PRIRAST STABALA KAO BIOINDIKATOR NJIHOVE VITALNOSTI: STUDIJA SLUČAJA SA PODRUČJA DESPOTOVCA

Istraživanje procesa devitalizacije i sušenja stabala vršeno je u veštački podignutoj sastojini crnog borana području Despotovca, Srbija. Analiziran je debljinski prirast 30 dominantnih stabala, razvrstanihna osnovu okularne ocene intenziteta devitalizacije u tri kategorije: zdrava (bez vidljivih simptomasušenja), devitalizovana (stabla sa proređenim krošnjama i slabo izraženim simptomima sušenja) i jakodevitalizovana (stabla sa suvim većim delom krošnje). Nakon procesa sinhronizacije debljinskog prirastastabala definisani su indeksi debljinskog prirasta ove tri kategorije stabala. U cilju kvantitativne ocenedevitalizacije i utvrđivanja procenta gubitka prirasta kod devitalizovanih i jako devitalizovanih stabalaračunati su i dvostruki indeksi, nastali stvaljanjem u odnos indeksa debljinskog prirasta jako devitalizovanihi devitalizovanih stabala sa indeksima debljinskog prirasta zdravih stabala.Rezultati su pokazali da kod svih kategorija stabala u periodu od 1960. do 2000. godine postoje slučajnevarijacije indeksa debljinskog prirasta i preklapanje linija njihovih tokova, bez nekih jasnih razlika u‘’šablonu’’ reakcije na prisutne stimulativne i ograničavajuće faktore rasta. Jasna i izražena odstupanjau prirastu zdravih, sa jedne strane i devitalizovanih i jako devitalizovanih stabala, sa druge strane,utvrđena su od 2008. godine. Prirast jako devitalizovanih stabala u 2014. godini iznosio je nešto manjeod 42%, a devitalizovanih 67% ostvarenog prirasta zdravih stabala. Daljom analizom indeksa prirastastabala uočeno je da razlike u prirastu ovih kategorija stabala počinju da se pojavljuju još od 2000. godine.Ova činjenica upućuje na zaključivanje da je proces stvarne devitalizacije stabala počeo pre oko15 godina, kada nije bilo nikakvih vidljivih simptoma.

Impacts of climate change on annual diameter increment of natural Calabrian pine (Pinus brutia Ten.) forests in Kahramanmaras

The effects of global warming on climate change have been recognized in global scale and it is expected that these effects will become even more obvious in near future. The climate change, especially in arid, semi-arid, and semi-humid regions, may result in detrimental effects on forests and water resources. Turkey is among the most affected countries from climate change due to located in Mediterranean region. With the global climate change, dams and ponds also influence on tree growth. This study was carried out in Menzelet watershed dam located in Kahramanmaras, Turkey. Menzelet dam was established during 1980-1989 and water deposition started in 1990. The climate of research area is semi-arid and characterized by extreme summer drought. The purpose of this study was to investigate the local climate effects on diameter increments resulted by Menzelet Dam Lake on the naturally distributed Calabrian pine (Pinus brutia Ten.) forests. Therefore, sampling areas were chosen from two different places namely as dam site and control site. Sample plots in dam site and control site were selected from the same stand structure and have the same properties such as site index, altitude, age distribution classes and aspect. Increment cores were taken from 20 Pinus brutia trees using increment borer at breast height (1.30 m) in each sample plots and two increment cores were taken from each tree. WinDENDRO software package was used on the measurement and determination of annual diameter increment. Annual diameter increment of trees in dam site and control site were compared with independent t test using SPSS 20.0 statistical program. The relationships between annual diameter increment and climatic factors such as temperature and precipitation were evaluated using Pearson correlation analysis. According to results, there is a statistically significant difference between average annual diameter increment in dam site and control site and dam influenced forest areas positively with respect to annual diameter increment. The values of the mean annual diameter increment of the trees in dam site are greatly higher than trees in control site. According to correlation analysis, temperature increase negatively affects annual diameter increment in control site. Important increase or decrease of annual total rainfall cause more significant changes in annual diameter increment in control site compare to dam site.

Radial increment dynamics in Pinus sylvestris stands within the Northern Steppe of Ukraine

The parameters of periodic increment (5-years) and peculiarities of its change depending on age, diameter, height and volume of trunk of Scots pine are determined. The influence of climate conditions (air temperature and precipitation) on the dynamics of radial increment change of Scots pine trees are established. The results of experimental studies, obtained from 20 temporary sample plots of pine stands within the Northern Steppe of Ukraine are presented. We conducted an estimate of radial increment of Scots pine trunks as a basis for development of normative and information support for assessment of biotic productivity of this category of forest. All selected sample trees had different age and biometric parameters. The age of sample trees ranged from 9 to 90 years; diameter at breast height – from 4.0 to 41.7 cm; height – from 4.2 to 30.0 m, trunk volume – from 0.002 to 1.748 m3. It is found that the radial increment of pine stem was significantly dependent on tree age. The highest values of radial increment of Scots pine trees were observed for trees aged up to 20 years. With increasing age, radial increment had a decreasing trend, including 90-year old trees. Regression models of the dependence of radial increment of pine trees on the age and diameter are presented. In the article, the dependence of the values of radial increment of sample trees from types of forest are demonstrated. The highest values of Scots pine radial increment was observed in sugruds and gruds, which were presented in tree samples of 20 years. Comparative analysis of radial increment change in the trees of one age category, which grew in different conditions, was conducted. The older trees had the maximum increment in the conditions of dry sugrud, and the minimum increment in conditions of fresh subor. Also in this article we used generalized chronology of Scots pine radial increment reflecting regional variability of growth in pine trees. The results supplemented the research obtained earlier with new data on the dependence of the pine radial growth rate on forest-biometric parameters. These experimental data, their graph-analytical evaluation yielded an information basis for modeling the radial increment of pine trees, created on the basis of dependence of this parameter on biometric indexes – age and diameter at breast height.

Validation and application of a new microwave-digestion/ICP-MS method for the analysis of trace metals in tree increment cores

Validation and application of a new microwave-digestion/ICP-MS method for the analysis of trace metals in tree increment cores

Enhancing binomial and trinomial equity option pricing models

We extend the classical Cox–Ross–Rubinstein binomial model in two ways. We first develop a binomial model with time-dependent parameters that equate all moments of the pricing tree increments with the corresponding moments of the increments of the limiting Itô price process. Second, we introduce a new trinomial model in the natural (historical) world, again fitting all moments of the pricing tree increments to the corresponding geometric Brownian motion. We introduce the risk-neutral trinomial tree and derive a hedging strategy based on an additional perpetual derivative used as a second asset for hedging at any node of the trinomial pricing tree.

Extreme mid-winter drought weakens tree hydraulic-carbohydrate systems and slows growth.

Rising temperatures and extended periods of drought compromise tree hydraulic and carbohydrate systems, threatening forest health globally. Despite winter's biological significance to many forests, the effects of warmer and dryer winters on tree hydraulic and carbohydrate status have largely been overlooked. Here we report a sharp and previously unknown decline in stem water content of three conifer species during California's anomalous 2015 mid-winter drought that was followed by dampened spring starch accumulation. Recent precipitation and seasonal vapor pressure deficit (VPD) anomaly, not absolute VPD, best predicted the hydraulic patterns observed. By linking relative water content and hydraulic conductivity (Kh ), we estimated that stand-level Kh declined by 52% during California's 2015 mid-winter drought, followed by a 50% reduction in spring starch accumulation. Further examination of tree increment records indicated a concurrent decline of growth with rising mid-winter, but not summer, VPD anomaly. Thus, our findings suggest a seasonality to tree hydraulic and carbohydrate declines, with consequences for annual growth rates, raising novel physiological and ecological questions about how rising winter temperatures will affect forest vitality as climate changes.

Competition Indices and Their Relationship With Basal Area Increment of Araucaria

Models that report the effect of competition are important for forest management since forests with higher levels of competition have lower increment rates, and their use is necessary to plan forest interventions. Thus, this study aimed to assess the effect of competition in the basal area increment of individual trees of Araucaria angustifolia (Bertol.) Kuntze in a natural forest. A total of 397 subject trees were measured, covering the diametric range. The dendrometric and morphometric characteristics of subject trees and their competitors were obtained, and 22 distance-dependent and distance-independent competition indices were calculated, in addition to increment cores extracted radially from the trunk at diameter at breast height. The relationship between models of periodic annual increment in basal area based on competition indices has allowed to obtain R2 values of 0.425 and Syx% ≥ 50.2. The multivariate technique of principal component analysis has shown that three principal components explain 78.43% of total variation. The first component was responsible for explaining 52.95%, with similar eigenvector for 11 competition indices, evidencing that these models can be used to describe especies competition, although they show different variables and mathematical equations in calculations. Results show the importance of competition to predict increment of Araucaria in individual trees.

A Distributed Indexing Method for Timeline Similarity Query

Timelines have been used for centuries and have become more and more widely used with the development of social media in recent years. Every day, various smart phones and other instruments on the internet of things generate massive data related to time. Most of these data can be managed in the way of timelines. However, it is still a challenge to effectively and efficiently store, query, and process big timeline data, especially the instant recommendation based on timeline similarities. Most existing studies have focused on indexing spatial and interval datasets rather than the timeline dataset. In addition, many of them are designed for a centralized system. A timeline index structure adapting to parallel and distributed computation framework is in urgent need. In this research, we have defined the timeline similarity query and developed a novel timeline index in the distributed system, called the Distributed Triangle Increment Tree (DTI-Tree), to support the similarity query. The DTI-Tree consists of one T-Tree and one or more TI-Trees based on a triangle increment partition strategy with the Apache Spark. Furthermore, we have provided an open source timeline benchmark data generator, named TimelineGenerator, to generate various timeline test datasets for different conditions. The experiments for DTI-Tree’s construction, insertion, deletion, and similarity queries have been executed on a cluster with two benchmark datasets that are generated by TimelineGenerator. The experimental results show that the DTI-tree provides an effective and efficient distributed index solution to big timeline data.

The facultative bimodal growth pattern in Quercus ilex – A simple model to predict sub-seasonal and inter-annual growth

In Mediterranean climates, bimodal growth patterns, corresponding to two peaks in radial increment during favorable seasons, have been described in several tree species. However, we lack a better mechanistic understanding of bimodality and its potential responses to the predicted warming and aridification trends. Filling this research gap is important since growth duration affects the capacity of trees to form wood and uptake carbon. Here we used an 11-year (1994–2004) long record of dendrometer data of the Mediterranean Holm oak (Quercus ilex) and compared how climate related to radial increment in trees from the south- and the north-facing slopes. We also related climate variables to tree-ring width and the production of intra-annual density fluctuations (IADFs), which reflects bimodality. In this paper, we introduce a model called VS-Lite2 to simulate tree-growth dynamics, which is a modified version of the process-based Vaganov-Shashkin Lite model. The VS-Lite2 model adequately reproduced the bimodal intra‐annual pattern of radial growth, IADFs, and annual tree growth. Trees from the south-oriented slope grew more, produced more IADFs and showed a more marked bimodal pattern than trees from the north-facing slope. These differences agree with the observation that late-summer drought constrained growth. Therefore, radial-growth models should consider plastic bimodality and micro-environmental conditions in areas subjected to seasonal droughts.

Stability of tree increment in relation to episodic drought in uneven-structured, mixed stands in southwestern Germany

Future increases in temperature and changes in precipitation patterns may negatively affect the growth performance of economically important tree species such as Norway spruce, which in the past have often been established and managed in monocultures. Structural diversity has been advocated as a silvicultural approach to increase resistance and resilience of forests to climate change extremes. Whether it promotes growth stability during and following drought years has not yet been analyzed. We investigated stem growth reactions to the extreme drought of 2003 in 23 uneven-structured, mixed Norway spruce and Silver fir stands in southwestern Germany. Using linear mixed-effects models we analyzed the resistance and resilience of basal area increment in relation to species identity, drought intensity, tree size, competition, density and diversity. Structural diversity, measured as variation in tree diameter at breast height, had no influence on increment stability during the extreme summer drought of 2003. Likewise, the effect of species diversity was weak and inconclusive. However, a higher presence of Silver fir in the mixture appeared to reduce increment stability in 2003 for both fir and spruce. Reducing competition through thinning counteracted this effect and promoted increment stability. Our findings indicate that the species identity of competitors in mixtures is a better predictor of stem growth reactions to drought than diversity. They support the conclusion that diversity does not generally increase stability to drought stress. Silver fir consistently showed a substantially higher increment resistance and resilience than spruce. Its resistance increased with diminishing drought intensity, yet spruce reacted uniformly, manifesting a low resistance across the whole drought intensity gradient. Spruce did not regain pre-drought growth levels within the first three years after drought, whereas fir did. We conclude that fir may be able to act as a silvicultural alternative to spruce under changing climatic conditions, given appropriate sites and thinning regimes. Considering the expected increase in drought intensity and frequency in the 21st century, understanding species interactions at the local scale emerges as an essential prerequisite for developing resilient forest stands.

Forest gardens management under traditional ecological knowledge in West Kalimantan, Indonesia

Winarni B, Lahjie AM, Simarangkir B.D.A.S., Yusuf S, Ruslim Y. 2018. Forest gardens management under traditional ecological knowledge in West Kalimantan, Indonesia. Biodiversitas 19: 77-84. Local wisdom of Dayak Kodatn people in West Kalimantan in forest management shows that human and nature are in one beneficial ecological unity known as Traditional Ecological Knowledge (TEK). Former cultivation forest areas are managed in various ways, including planting forest trees, fruit-producing plants, and rubber trees until they transform into the forest garden. This research used three models, monoculture rubber cultivation (Model 1), combined rubber and camphor cultivation (Model 2), and combined rubber and durian cultivation (Model 3). This research intended to: (i) analyze the production of rubber latex and durian fruit; (ii) analyze the growth increment of camphor and durian trees; (iii) analyze the financial feasibility of rubber tree plantation, combined rubber and camphor tree plantation, and combined rubber and durian trees plantation; (iv) formulate the model of rubber cultivation. This research also used measurement methods other than field measurement, which were tree diameter and height, rubber latex and durian fruit weight, and questionnaire interviews. The maximum productions of rubber latex from three models were achieved at the age of 17 years, while maximum production of durian fruits was achieved at the age of 55 years. The maximum growth increment of camphor and durian trees were achieved at the age of 40 years. Based on NPV analysis and IRR, those three models were worthy of being cultivated. Financially, the combined rubber and durian cultivation (Model 3) was the most profitable, followed by monoculture rubber cultivation (Model 1), and lastly the combined rubber and camphor cultivation (Model 2).

Ispitivanje korelacije između defolijacije izazvane ishranom larvi žutotrbe i prirasta infestiranih stabala hrastova kitnjaka i cera

The paper presents the results of the study research on the effect of the leaf mass reduction caused by the intensive nutrition of an oak defoliating insect - the brown-tail moth Euproctis chrysorrhoea on the annual increment of sessile oak and Turkey oak trees in the coppice forests of the Novi Pazar region (SE Srbijašume, FE Šumarstvo Raška, Novi Pazar Forest Administration, FMU Blizanac-Debelica and FMU NinajaKoznik).

Rehabilitation and soil conservation of degraded land using sengon (Falcataria moluccana) and peanut (Arachis hypogaea) agroforestry system

Sarminah S, Karyati, Karmini, Simbolon J, Tambunan E. 2018. Rehabilitation and soil conservation of degraded land using sengon (Falcataria moluccana) and peanut (Arachis hypogaea) agroforestry system. Biodiversitas 19: 222-228. Rehabilitation and soil conservation effort on degraded lands is not always a success. Multiple factors, such as the field’ biogeophysical conditions and the choice of suitable plant species determine the effectivity of the rehabilitation program. Our research aimed to implement agroforestry system of sengon (Falcataria moluccana) and peanut (Arachis hypogaea) on degraded land at different soil slopes (a steep and a slightly steep slope gradient) and to analyze the effect of the system on silvicultural and hydro-orological aspects of the degraded land. The silvicultural parameters examined in this study were the ground coverage of peanut growth and the stem diameter and height of sengon trees. Meanwhile, the hydro-orological parameters included potential erosion rate, erosion hazard index, and erosion hazard level. Our study revealed that on the land with the slightly steep slope (15-25%), the survival rate of sengon reached 90%, the ground coverage of the peanuts was 70-80%, the diameter and height increment of sengon trees reached 2.47 cm/year and 17.58 cm/year, respectively. Meanwhile, the potential erosion rate was 20.05 ton/ha/year, with an erosion hazard index of 0.80 (low) and a low hazard level. In the steeper ground (25-40%), the survival rate of sengon reached 90%, the peanut coverage was 50-60% and the diameter and height increment of the sengon were 2.37 cm/year and 16.41 cm/year, respectively. In the steep ground, potential erosion rate was 45.50 ton/ha/year, with an erosion hazard index of 3.25 (moderate) and a low hazard level. We concluded that the rehabilitation and soil conservation using sengon-peanut agroforestry system effectively suppressed erosion rate to a low erosion hazard.

Dynamics of natural conditions around modern glaciation location at the Eastern Sayan

Mountain massif Munku-Sardyk presents the highest mountain range and adjacent Stanovoy ridge highlands of the Eastern Sayan. There is situated modern glaciation site which was the most studied in the course of last 160 years. This periglacial area experienced different periods of cooling and warming in the Holocene and retained traces of the Sartan glaciation of Subboreal (3000–5000 years ago), the Little Ice Age, the evidences of Holocene optimum and general warming last time. The authors examined the variability of activity of modern glaciation and variation of natural conditions of the periglacial zone on climate and on dendrochronological data. Results of larch and Siberian stone pine growth data were revealed at the higher border of forest communities. Analysis of the growth of the “fossil” tree in the Holocene optimum showed that the absolute magnitude of its increment was two times higher than for up-to-date long-lived trees. Identified periods of the Peretolchin glacier retreat in 1900–1965 and 1983–2000 years took place with increased growth of trees and the rate of sedimentation in proglacial lake, and vice versa glacier advance on in 1965–1980 years was accompanied by slowing of tree increments and reduction in sedimentation rate. Since 2000, there has been growth of trees instability associated with a decrease in average monthly summer temperatures.

Regression Modeling of the Radial Increment Dynamics in Scots Pine in Forests Contaminated with Radionuclides in Bryansk Oblast

We study the dynamics of radial increment in Scots pine in the forests of Bryansk oblast contaminated with radionuclides after the Chernobyl disaster. We have developed regression models of the relationship between specific soil activity and the radial increment of trees for the transition stage of the disaster in 1987–1989 and four 5-year-long periods from 1990 to 2009, characterizing 20 years of the recovery period. We have found a strong positive correlation between the radial increment and specific soil activity. The correlation coefficients vary from 0.695 ± 0.198 to 0.895 ± 0.124 for early increment, and from 0.549 ± 0.231 to 0.937 ± 0.097 for late increment in different time periods. It is found that the cubic parabolic equation is the optimal statistical description of the relationship between the radial increment and concentration of radiocesium in soil. The minimal effective specific soil activity for the stimulation of radioactivity decreased from 25–26 kBq kg–1 in 1987–1989 to 9–10 kBq kg–1 in 2004–2009. The same value for the late increment varied from 20–21 to 16–17 kBq kg–1 in the same periods. The maximal effective specific soil activity indicative of the highest effect of radiation decreased consequently from 110–120 kBq kg–1 in 1987–1989 to 60–70 kBq kg–1 in 2004–2009 for early increment. The same value for late increment varied in the same range with no tendencies in the same periods. Based on the model of radial increment dynamics, we assessed the role of radiation in the elevation of standing volume in a typical pine forest in the study area 25 years after the Chernobyl disaster.

Dynamic growth models for continuous cover multi-species forestry in Iranian Caspian forests

This study concerns some of the relevant topics of the Iranian Caspian forestry planning problem, in particular the first central components in this modelling process, such as forest modelling, forest statistics and growth function estimations. The required data was collected from Iranian Caspian forests. To do so, 201 sample plots were determined and the parameters such as number of trees, tree diameter at breast height and tree height were measured at each sample plot. Three sample plots at different 3 elevations were chosen to measure the tree increment. Data has been used to estimate a modified logistic growth model and a model that describes the growth of the basal area of individual trees as a function of basal area. General function analysis has been applied in combination with regression analysis. The results are interpreted from ecological perspectives. Furthermore, a dynamic multi-species growth model theory is developed and analysed with respect to dynamic behaviour, equilibria, convergence and stability. Logistic growth models have been found applicable for continuous cover forest management optimization. Optimization of management decisions in a changing and not perfectly predictable world should always be based on adaptive optimization.

Влияние метеофакторов на радиальный прирост культур дуба черешчатого в правобережном лесничестве УОЛ ВГЛТУ имени Г.Ф. Морозова

Exploring linkages between trees increment and meteorological elements is of great importance for understanding biological processes, assess of environmental determinants, defining growth and productivity of forest communities, forecasting growth in connection with changing climatic conditions. Dendroclimatic analysis can be used in planning and implementation of many forestry activities. The paper presents data on the effect of meteorological factors on the radial increment of English oak in isotopologues cultures originating from glague oak forest of serotinous variety. Dendrochronological analysis of radial growth was carried out in accordance with existing methodological developments. In the dynamics of radial growth of trees of English oak, periodicity is observed. 2-3-, 5-7-, 11-, 22-year cycles are seen more clearly. Growth depression is mainly due to the summer droughts with temperatures above average standards and rainfall less than average annual norms. Periods with high radial growth occur in years with high air temperatures and rainfall more than average standards. In terms of impact on the radial increment of English oak meteorological elements are arranged in the following order: hydrometric ratio; precipitation – autumn-winter, summer, annual; air temperature in the vegetation period of active growing season (April, May), summer, annual. Data on the influence of meteorological elements are confirmed by the results of analysis of variance. The highest power of the influence of the hydrothermal coefficient (HTC) is 0.39, with precipitation of the warm period of is, the sum of precipitation for the year of is, the lowest effect with temperature is 0.20. Between the air temperature and increment in the warm period there is an inverse relationship: the increase in air temperature reduces growth. Both excess of precipitation and the shortage contribute to the reduction of radial growth.

Anthropogenic nitrogen deposition alters growth responses of European beech (Fagus sylvativa L.) to climate change.

Global change affects the functioning of forest ecosystems and the services they provide, but little is known about the interactive effects of co-occurring global change drivers on important functions such as tree growth and vitality. In the present study we quantified the interactive (i.e. synergistic or antagonistic) effects of atmospheric nitrogen (N) deposition and climatic variables (temperature, precipitation) on tree growth (in terms of tree-ring width, TRW), taking forest ecosystems with European beech (Fagus sylvatica L.) as an example. We hypothesised that (i) N deposition and climatic variables can evoke non-additive responses of the radial increment of beech trees, and (ii) N loads have the potential to strengthen the trees' sensitivity to climate change. In young stands, we found a synergistic positive effect of N deposition and annual mean temperature on TRW, possibly linked to the alleviation of an N shortage in young stands. In mature stands, however, high N deposition significantly increased the trees' sensitivity to increasing annual mean temperatures (antagonistic effect on TRW), possibly due to increased fine root dieback, decreasing mycorrhizal colonization or shifts in biomass allocation patterns (aboveground vs. belowground). Accordingly, N deposition and climatic variables caused both synergistic and antagonistic effects on the radial increment of beech trees, depending on tree age and stand characteristics. Hence, the nature of interactions could mediate the long-term effects of global change drivers (including N deposition) on forest carbon sequestration. In conclusion, our findings illustrate that interaction processes between climatic variables and N deposition are complex and have the potential to impair growth and performance of European beech. This in turn emphasises the importance of multiple-factor studies to foster an integrated understanding and models aiming at improved projections of tree growth responses to co-occurring drivers of global change.

Stem and root diameter growth of European beech and Norway spruce under extreme drought

Abstract Current and future climate change will be accompanied by more frequent and more severe drought events, with potential impacts on tree growth and forest stand productivity. Tree growth response may depend on its water status and on the competition or facilitation of the neighbouring trees. We analysed inter- and intra-annual diameter increments of European beech and Norway spruce trees within a mixed forest stand for two treatments, i.e., with and without rainfall exclusion and for two neighbourhood competition situations of the two climatically contrasting years 2014 and 2015. Rainfall exclusion by roofs at about 3 m height induced soil drought under 116 trees, particularly supported in the year 2015 by hot and dry weather conditions. The effects of extreme drought was examined at three levels, i.e. at two stem heights and at the main coarse root of 48 trees with inter- and intraspecific neighbourhood. We found species specific diameter growth performances during the year at all three levels. Compared to beech trees annual diameter increments of spruce trees were in most cases significantly higher in the year 2014, while in the drought year 2015 no significant differences between the two species were obvious. Under the heavy drought by the rainfall exclusion experiment and by the hot year 2015 diameter increments were significantly smaller for spruce trees at all three levels whereas for beech trees at all levels no significant differences were obvious. The diameter growth differences between inter- and intraspecific neighbourhood were in most cases small and not significant. In the drought year 2015 beech trees in intraspecific neighbourhood grew better at all levels compared to interspecific neighbourhood, with a significantly higher growth rate at the upper stem level. Reasons for the species specific reactions patterns on drought were discussed (phenology, water balance, species specific physiological reactions).

Long-term trends in leaf level gas exchange mirror tree-ring derived intrinsic water-use efficiency of Pinus cembra at treeline during the last century

The ability of treeline conifers in the Central European Alps to cope with recent climate warming and increasing CO2 concentration is still poorly understood. We determined basal area increment (BAI) and tree ring stable carbon isotope ratios (δ13C) of Pinus cembra trees from 1925 through 2013. Stable isotope ratios and BAI were compared with leaf level gas exchange measurements carried out in situ between 1934 and 2012, and thus, provided new insights into long-term trends of tree-ring derived intrinsic water-use efficiency (iWUE). Mature P. cembra trees at treeline responded to increasing Ca and air temperature with a parallel increase in maximum net CO2 uptake rate at ambient CO2 (Amax) and tree-ring-derived intercellular CO2 partial pressure (Ci). Amax tripled and was positively correlated to BAI and Ci. The latter increased in parallel with ambient CO2 concentration and stomatal conductance. In contrast to the instantaneous gas exchange parameters, δ13C derived iWUE informs about the long-term changes in the carbon water relations. These data showed three changes in the iWUE chronosequences, which could be identified with different long term gas exchange patterns: (1) from stomatal controlled functioning from 1925 to 1981, to a situation where (2) both net CO2 fixation (A) and leaf conductance for water vapour (gw), responded to the environment from 1982 to 1997, and (3) back to a stomata controlled pattern over iWUE from 1998 onwards. This temporal pattern was also mirrored in leaf level gas exchange assessments, suggesting a parallel increase of A and gw of P. cembra at treeline during the last nine decades.