Tree Growth Potential Research Articles

Future carbon sequestration potential in a widespread transcontinental boreal tree species: Standing genetic variation matters!

Climate change (CC) necessitates reforestation/afforestation programs to mitigate its impacts and maximize carbon sequestration. But comprehending how tree growth, a proxy for fitness and resilience, responds to CC is critical to maximize these programs' effectiveness. Variability in tree response to CC across populations can notably be influenced by the standing genetic variation encompassing both neutral and adaptive genetic diversity. Here, a framework is proposed to assess tree growth potential at the population scale while accounting for standing genetic variation. We applied this framework to black spruce (BS, Picea mariana [Mill] B.S.P.), with the objectives to (1) determine the key climate variables having impacted BS growth response from 1974 to 2019, (2) examine the relative roles of local adaptation and the phylogeographic structure in this response, and (3) project BS growth under two Shared Socioeconomic Pathways while taking standing genetic variation into account. We modeled growth using a machine learning algorithm trained with dendroecological and genetic data obtained from over 2600 trees (62 populations divided in three genetic clusters) in four 48-year-old common gardens, and simulated growth until year 2100 at the common garden locations. Our study revealed that high summer and autumn temperatures negatively impacted BS growth. As a consequence of warming, this species is projected to experience a decline in growth by the end of the century, suggesting maladaptation to anticipated CC and a potential threat to its carbon sequestration capacity. This being said, we observed a clear difference in response to CC within and among genetic clusters, with the western cluster being more impacted than the central and eastern clusters. Our results show that intraspecific genetic variation, notably associated with the phylogeographic structure, must be considered when estimating the response of widespread species to CC.

Can SPAD Values and CIE L*a*b* Scales Predict Chlorophyll and Carotenoid Concentrations in Leaves and Diagnose the Growth Potential of Trees? An Empirical Study of Four Tree Species

Photosynthetic pigments are fundamental for plant photosynthesis and play an important role in plant growth. Currently, the frequently used method for measuring photosynthetic pigments is spectrophotometry. Additionally, the SPAD-502 chlorophyll meter, with its advantages of easy operation and non-destructive testing, has been widely applied in land agriculture. However, the application prospects of its test results in horticultural plants have not yet been proven. This study examines the reliability of SPAD values for predicting chlorophyll concentrations. Using fresh and senescent leaves from four common horticultural plants, we measured SPAD values, photosynthetic pigment concentrations, and leaf color parameters. A generalized linear mixed model demonstrated that SPAD values are a reliable indicator for predicting chlorophyll concentrations, yet interspecific variations exist. Based on the predictive power of SPAD values for chlorophyll, we first propose an Enrichment Index (CEI) and a Normal Chlorophyll Concentration Threshold (NCCT). The CEI can be used to compare SPAD values among different species, and the NCCT value can serve as a more accurate indicator for assessing the growth potential of old trees. However, due to a limited sample size, further research with larger samples is needed to refine the diagnosis of plant growth potential and enhance the management of ornamental plant cultivation.

Tree growth potential and its relationship with soil moisture conditions across a heterogeneous boreal forest landscape

Forest growth varies across landscapes due to the intricate relationships between various environmental drivers and forest management. In this study, we analysed the variation of tree growth potential across a landscape scale and its relation to soil moisture. We hypothesised that soil moisture conditions drive landscape-level variation in site quality and that intermediate soil moisture conditions demonstrate the highest potential forest production. We used an age-independent difference model to estimate site quality in terms of maximum achievable tree height by measuring the relative change in Lorey’s mean height for a five year period across 337 plots within a 68 km2 boreal landscape. We achieved wall-to-wall estimates of site quality by extrapolating the modelled relationship using repeated airborne laser scanning data collected in connection to the field surveys. We found a clear decrease in site quality under the highest soil moisture conditions. However, intermediate soil moisture conditions did not demonstrate clear site quality differences; this is most likely a result of the nature of the modelled soil moisture conditions and limitations connected to the site quality estimation. There was considerable unexplained variation in the modelled site quality both on the plot and landscape levels. We successfully demonstrated that there is a significant relationship between soil moisture conditions and site quality despite limitations associated with a short study period in a low productive region and the precision of airborne laser scanning measurements of mean height.

Species admixture can increase potential tree growth and reduce competition

Trees often show better growth in mixed as opposed to monospecific neighborhoods as consequence of competition reduction and facilitation between species. However, it can be challenging to discern the effect of these factors as they occur simultaneously, so often they are jointly refereed as complementarity. By using tree growth models based on potential tree growth reduced by a competition modifier and including species mixing effects on both components (potential tree growth and competition modifier), we aim to verify that tree potential growth is modified by admixture, which may provide further information on species interactions and complementarity.We used tree data from the Spanish National Forest Inventory, selecting plots located in two different mixtures, Scots pine – European beech and Scots pine – Oak mixtures, as well as in the corresponding monospecific stands of those species. To analyse whether the species mixture increases the potential basal area growth, we developed linear mixed quantile regressions to model the potential growth, while to analyse the competition reduction we developed linear mixed models. We include the Martonne aridity index as a measure of the site conditions in the models to explore whether climate conditions modify the effects of species mixture.Our results show a slight effect of the mixture on the potential basal area growth of pine while the potential growth of beech clearly benefited from the pine/beech mixtures. For the pine/oak mixtures the potential growth of both species was higher in mixtures than in monospecific stands. Moreover, we found a positive influence of humidity on potential growth for all the species and mixtures, although the magnitude of the effect was less important for beech and more notable in the case of the pine/oak mixtures. We also found that for the studied species, admixed species reduced competition, with lower inter-specific than intra-specific competition effects, and that these effects were mediated by climate conditions.We concluded that the potential tree basal area growth is influenced by the species admixture, which suggest that species mixing effects can be relevant also under low stand densities. Our results highlight the importance of integrating the effect of species interactions on both the potential growth of trees and the competition modifier when the aim of the research is to further our understanding of species interactions.

Pruning height and frequency of Moringa oleifera and Leucaena leucocephala in a silvopastoral system

Objective: To evaluate two different heights (50 and 70 cm) and pruning frequencies (60 and 135 days) in Moringa oleifera and Leucaena leucocephala in a developing silvopastoral system. Design/methodology/approach: Four treatments were established: T1=Moringa oleifera with pruning at 50 cm; T2=Moringa oleifera with pruning at 70 cm; T3=Leucaena leucocephala with pruning at 50 cm; and T4=Leucaena leucocephala with pruning at 70 cm. In all cases, pruning frequencies were 60 and 135 days. The number of sprouts, diameter, and length of the largest sprout, as well as the amount of biomass, were recorded. A mixed model, variance analysis, and Tukey's test were used to analyze the data. Results: The number of regrowths for L. leucocephala was higher than for M. oleifera. Treatment T2 had the highest performance at day 60; in the case of L. leucocephala, performance was similar between pruning frequencies. For T2, diameter and length were larger at both frequencies; for T3, at 60 days; and for T4, at 135 days. Biomass was higher for M. oleifera than for L. leucocephala, while pruning at 70 cm was better than at 50 cm. Pruning at 135 days produced a higher biomass than at 60 days. For T2, biomass was higher at 60 days, while for T1 and T4, it was higher at 135 days. Study limitations/implications: Forage species, as well as pruning frequencies and heights, determine tree growth potential and the amount of biomass available for animals. Findings/conclusions: The agronomic performance of Leucaena leucocephala has a better response to pruning, regardless of pruning height and frequency, in a silvopastoral system.

Selection in space and time: Individual tree growth is adapted to tropical forest gap dynamics.

Tropical forest dynamics are driven by growth and survival strategies of tree species in relation to treefall gaps; however, the ecological and evolutionary roles of intraspecific variation in the response to forest gaps remain unexplored. Here, we associated genomic data of three related tree species of the genus Symphonia in a French Guiana forest with (1) each individual tree's growth potential, and (2) with its light and competition environment estimated based on 33years of forest monitoring in plots covering 120ha. We show that individual trees within species have genetically determined growth strategies that are adapted to the local light and competition environments, which are shaped by the time since the last treefall. Within species, fast-growing genotypes are more frequent in light-enriched environments and slow-growing genotypes in more shaded environments. Forest gap dynamics is thus a strong selection driver that shapes adaptive strategies and maintains genetic variation within tropical tree species.

Effects of Stem Density on Crown Architecture of Scots Pine Trees.

Trees adapt to their growing conditions by regulating the sizes of their parts and their relationships. For example, removal or death of adjacent trees increases the growing space and the amount of light received by the remaining trees enabling their crowns to expand. Knowledge about the effects of silvicultural practices on crown size and shape and also about the quality of branches affecting the shape of a crown is, however, still limited. Thus, the aim was to study the crown structure of individual Scots pine trees in forest stands with varying stem densities due to past forest management practices. Furthermore, we wanted to understand how crown and stem attributes and also tree growth affect stem area at the height of maximum crown diameter (SAHMC), which could be used as a proxy for tree growth potential. We used terrestrial laser scanning (TLS) to generate attributes characterizing crown size and shape. The results showed that increasing stem density decreased Scots pine crown size. TLS provided more detailed attributes for crown characterization compared with traditional field measurements. Furthermore, decreasing stem density increased SAHMC, and strong relationships (Spearman’s correlations > 0.5) were found between SAHMC and crown and stem size and also stem growth. Thus, this study provided quantitative and more comprehensive characterization of Scots pine crowns and their growth potential. The combination of a traditional growth and yield study design and 3D characterization of crown architecture and growth potential can open up new research possibilities.

Tree potential growth varies more than competition among spontaneously established forest stands of pedunculate oak (Quercus robur)

Key messageAnalyses of dendrochronological data from 15 recently established tablished stands of pedunculate oak (Quercus robur L.) revealed that functions describing potential tree growth in the absence of neighbours varied more between stands than functions describing competitive effects of conspecific neighbours. This suggests that competition functions can more easily be transferred among stands than potential growth functions.ContextThe variability inherent in the natural establishment of tree stands raises the question whether one can find general models for potential growth and competition that hold across stands.AimsWe investigated variation in potential growth and competition among recently established stands of Q. robur and tested whether this variation depends on stand structure. We also tested whether competition is symmetric or asymmetric and whether it is density-dependent or size-dependent. Lastly, we examined whether between-year growth variation is synchronous among stands.MethodsPotential growth, competition and between-year growth variation were quantified with statistical neighbourhood models. Model parameters were estimated separately for each stand using exhaustive mapping and dendrochronology data.ResultsCompetition was best described with an asymmetric size-dependent model. Functions describing potential growth varied more among forest stands than competition functions. Parameters determining these functions could not be explained by stand structure. Moreover, annual growth rates showed only moderate synchrony across stands.ConclusionThe substantial between-stand variability in potential growth needs to be considered when assessing the functioning, ecosystem services and management of recently established Q. robur stands. In contrast, the relative constancy of competition functions should facilitate their extrapolation across stands.

Determination of Competition Factor for Tree Growth within A Stand

This study has two purposes; the first one is development of a new method in determining a competition factor for Pinus brutia trees grown in a stand, and the second one is development of a theoretical method for determination potential growth of individual trees within a stand. This potential growth can be used to estimate the growth of a tree as if it grows in a competition free area. Competition between trees has a strong effect on growth potential.  Dense forests need thinning to ensure providing the essential growth requirements. The developed factor can be used to give the answer for when and how much of stocking should be removed. Two samples of trees were selected, one from an open grown area and the other from forest stands. For each sample many regression equations were developed, for regressing, the diameter growth with different forms of diameter. The developed equations were undergone many tests of precision, to determine the one that best fits the dataset. At last the equation,, and equation  were finally selected for regressing the diameter growth with diameter at breast height for trees grown in a stand and open grown trees respectively. These selected equations were used to calculate the competition factor. Furthermore the equation; was finally selected among 23 others to be used for calculating the growth potential of trees grown within a stand.

Differences in tree growth of Norway spruce under rotation forestry and continuous cover forestry

In Fennoscandia there is still lack of information for comparing the traditional even-aged management approach, or Rotation Forestry (RF), with the alternative uneven-aged management, or Continuous Cover Forestry (CCF), especially at tree level. We compared the basal area growth of more than 9000 individual Norway spruces (Picea abies (L.) Karst.), repeatedly measured in long-term permanent sample plots in both RF and CCF stands (the latter managed with single tree selection). We fitted a descriptive model considering characteristics related to tree growth potential (tree size and crown ratio), stand characteristics, site fertility, and management activities (namely forest management type, intensity and timing of last cutting before growth). Variables related to the individual tree characteristics were the most important predictors for growth. The model included two competition indexes, asymmetric (based on total basal area) and symmetric (based on on the amount of overtopping), which had both a stronger negative effect in CCF than in RF. Stand development stage (expressed by the mean height) had a slightly negative effect only in RF. Variables directly describing the intensity and timing of the cuttings had such a negligible effect in both management systems that they were discarded, likely due to their already indirect effects on modifying the stand-level structure (i.e. in reducing the competition effect). Concluding, we successfully fitted a biologically sound and accurate descriptive model that can be used in the ongoing comparison of the two management approaches. CCF trees had a consistently lower growth due to a stronger effect of the competition variables in the model. Our methods show that there is need to account for the differences in the forest structure when building a model aimed at different management systems.

Low‐productivity boreal forests have high conservation value for lichens

Abstract Land set aside for preservation of biodiversity often has low productivity. As biodiversity generally increases with productivity, due to higher or more diverse availability of resources, this implies that some of the biodiversity may be left unprotected. Due to a lack of knowledge on the species diversity and conservation value of low‐productivity habitats, the consequences of the biased allocation of low‐productivity land for set‐asides are unknown. We examined the conservation value of boreal low‐productivity forests (potential tree growth <1 m3 ha−1 year−1) by comparing assemblages of tree‐ and deadwood‐dwelling lichens and forest stand structure between productive and low‐productivity forest stands. We surveyed 84 Scots pine‐dominated stands in three regions in Sweden, each including four stand types: two productive (managed and unmanaged) and two low‐productivity stands (on mires and on thin, rocky soils). Lichen species richness was the highest in low‐productivity stands on thin soil, which had similar amounts and diversity of resources (living trees and dead wood) to productive unmanaged stands. Stands in low‐productivity mires, which had low abundance of living trees and dead wood, hosted the lowest lichen richness. Lichen species composition differed among stand types, but none of them hosted unique species. The differences in both species richness and composition were more pronounced in northern than in southern Sweden, likely due to shorter history of intensive forestry. Synthesis and applications. Boreal low‐productivity forests can have as high conservation value as productive forests, which should be reflected in conservation strategies. However, their value is far from uniform, and conservation planning should acknowledge this variation and not treat all low‐productivity forests as a uniform group. Some types of low‐productivity forest (e.g. on rocky soil) are more valuable than others (e.g. on mires), and should thus be prioritized in conservation. It is also important to consider the landscape context: low‐productivity forests may have higher value in landscapes where high‐productivity forests are highly influenced by forestry. Finally, although low‐productivity forests can be valuable for some taxa, productive forests may still be important for other taxa.

Statistical Analysis of the Effects of Barking on Growth Potential in Xishuangbanna Area

Xishuangbanna is the most important tropical rainforest region in southwestern China, with important ecological and economic value. In order to obtain the huge economic benefits of planting Pu’er tea, the local people often use the method of ‘annular barking’ for the trees suitable for planting tea trees, so that the tea trees can absorb more nutrients and thus obtain higher economic benefits. In this paper, random sampling method is used to collect data of 12 species of trees totaling 1753 samples in Xishuangbanna where cases of barking happen frequently. By collecting the data such as the year of barking, the growth environment of trees and the growth potential of trees, using linear regression analysis, a regression equation for the tree growth potential and the year of the barking. Through analysis, it is found that the growth potential of the barked trees is negatively correlated with the years after being barked, and the regression equation for the relationship between survival rate and years after being barked is: Y=46.366-8.289x. The conclusion of this study will provide evidence of the tree damage and deaths caused by barking for forest police in Xishuangbanna, and provide strong theoretical support for the effective fight against criminals.

Use of Biostimulants for Organic Apple Production: Effects on Tree Growth, Yield, and Fruit Quality at Harvest and During Storage.

The experiment was conducted during two consecutive seasons (years 2016 and 2017) in an organic apple orchard of the cultivar Jonathan. Several biostimulants were tested (10 in total), including humic acids, macro and micro seaweed extracts, alfalfa protein hydrolysate, amino acids alone or in combination with zinc, B-group vitamins, chitosan and a commercial product containing silicon. Treatments were performed at weekly intervals, starting from the end of May until mid-August. The macroseaweed extract was effective in stimulate tree growth potential in both years, as shown by a significantly larger leaf area (+20% as compared to control) and by an higher chlorophyll content and leaf photosynthetic rate in year 2016. As for the yield performances and apples quality traits at harvest (average fruit weight, soluble solids content, titratable acidity, and flesh firmness), they were generally affected by the different climatic conditions that characterized the two growing seasons (year 2017 being characterized by higher maximal and average temperatures and by limited rainfalls at the beginning of the season). Treatments with macroseaweed extract, B-group vitamins and alfalfa protein hydrolysate were able to significantly improve the intensity and extension of the red coloration of apples at harvest. Correspondingly, the anthocyanin content in the skin of apples treated with the same biostimulants resulted significantly higher than control, highlighting the potential influence of these substances on the synthesis of secondary metabolites in apple. The incidence of physiological disorders was also monitored during apple storage period. Amino acids plus zinc application was effective in reducing (more than 50%) the incidence of the “Jonathan spot,” the main post-harvest disorder for this cultivar.

Simulating Climate Change Impacts on Hybrid-Poplar and Black Locust Short Rotation Coppices

In Brandenburg, north-eastern Germany, climate change is associated with increasing annual temperatures and decreasing summer precipitation. Appraising short rotation coppices (SRCs), given their long-time planning horizon demands for systematic assessments of woody biomass production under a considerable spectrum of climate change prospects. This paper investigates the prospective growth sensitivity of poplar and black locust SRCs, established in Brandenburg to a variety of weather conditions and long-term climate change, from 2015 to 2054, by a combined experimental and simulation study. The analysis employed (i) a biophysical, process-based model to simulate the daily tree growth and (ii) 100 realisations of the statistical regional climate model STAR 2K. In the last growing period, the simulations showed that the assumed climate change could lead to a decrease in the woody biomass of about 5 Mg ha−1 (18%) for poplar and a decrease of about 1.7 Mg ha−1 (11%) for black locust trees with respect to the median observed in the reference period. The findings corroborate the potential tree growth vulnerability to prospective climatic changes, particularly to changes in water availability and underline the importance of coping management strategies in SRCs for forthcoming risk assessments and adaptation scenarios.

Contrasting Patterns of Tree Growth of Mediterranean Pine Species in the Iberian Peninsula

Wood formation is the primary biological process through which carbon is durably sequestered in woody plants, and is thus a major contributor to mitigate climate change. We analyzed the tree growth patterns of four conifer species across the Iberian Peninsula (IP) based on a dense dendrochronological network (179 sites) combined with a high resolution climate dataset. Generalized linear-mixed models were used to predict the potential tree growth of different pine species under different climate conditions considering different age classes. We found a strong age dependency of tree growth, significant variations across the climate gradients, and a significant interaction of both age and climate effects on the four species considered. Overall, Pinus halepensis was the species with the highest climate sensitivity and the highest growth rates in all age classes and across its distribution area. Due to its stronger plastic character and its potential adaptability, Pinus halepensis was demonstrated to be the most suitable species in terms of tree growth and potentiality to enhance carbon sequestration in the IP. Since its potential distribution largely exceeds its actual distribution, P. halepensis arises as a key species to cope with future climate conditions and to keep fixing carbon regardless of the climatic circumstances.

Crown radius of pedunculate oak (Quercus robur L.) depending on stem size, stand density and site productivity

Crown size is a good indicator of the growth potential of trees and is often used in forest management for outlining thinning guidelines or constructing forest growth models. The aim of this study was to analyse mean crown radius as a function of stem size, stand density and site productivity in even-aged stands of pedunculate oak (Quercus robur L.). Data included measurements of 620 trees from 53 plots in nine thinning experiments and one operational stand in Sweden, Denmark and Great Britain, representing a wide spectrum of thinning practices ranging from the strictly unthinned control to extremely heavy thinning with essentially solitary trees. Three sets of models were constructed based on different predictor variables, including indicators of individual stem size (diameter at breast height, DBH), stand density/thinning grade (quadratic mean diameter and stand basal area) and site productivity (stand top height). Preliminary results indicated a significant effect of DBH and (nominal) thinning grade on crown radius. The response pattern of the final models indicated an increasing crown radius with increasing DBH, with increasing thinning grade (decreasing stand density) and with decreasing site productivity. The models are valid for predicting the crown radius of pedunculate oak in even-aged forest stands.

A spatial and temporal drought risk assessment of three major tree species in Britain using probabilistic climate change projections

Probabilistic climate data have become available for the first time through the UK Climate Projections 2009, so that the risk of change in tree growth can be quantified. We assessed the drought risk spatially and temporally using drought probabilities calculated from the weather generator data and tree species vulnerabilities using Ecological Site Classification model across Britain. We evaluated the drought impact on the potential yield class of three major tree species (Picea sitchensis, Pinus sylvestris, and Quercus robur), which cover around 59 % (400,700 ha) of state-managed forests, across the lowlands and uplands. We show that drought impacts result mostly in reduced tree growth over the next 80 years when using B1, A1B, and A1FI IPCC emissions scenarios, but varied spatially. We found a maximum reduction of 94 % but also a maximum increase of 56 % in potential stand yield class in the 2080s from the baseline climate (1961–1990). Furthermore, potential production over the state-managed forests for all three species in the 2080s is estimated to decrease due to drought by 42 % in the lowlands and by 32 % in the uplands in comparison to the baseline climate. Our results reveal that potential tree growth and forest production on the state-managed forests in Britain is likely to reduce, and indicate where and when adaptation measures are required. Moreover, this paper demonstrates the value of probabilistic climate projections for an important economic and environmental sector.

Estimation of potential impacts of climate change on growth and yield of temperate tree species

Studies assessing impacts of climate change on forests are numerous, but most evaluate potential tree growth for current and future conditions at discrete time intervals, which is generally insufficient for developing short to medium term forest policies and strategies. Analysis of forest growth and yield during the transition period of climate change is essential in supporting forest management activities in the midst of climate change. A gap model (JABOWA-3) was used to quantify the impact of climate change on major commercial tree species native to Nova Scotia, Canada. Tree species were projected to respond differently to the same level of temperature change. Yields from maples (Acer rubrum and saccharum), beech (Fagus grandifolia), and white pine (Pinus strobus) were projected to increase in response to increasing temperatures; whereas, yields from balsam fir (Abies balsamea), eastern larch (Larix laricina), red spruce (Picea rubens), trembling aspen (Populus tremuloides), and white birch (Betula papyrifera) were projected to decline. Species-specific modifiers of basal area (BA) yield calculated in this study can be used to adjust stand yield predictions. Nine species-specific regression models were developed to facilitate prediction of BA from current conditions as a function of growing degree days increments. Together, yield-modifiers and BA-response models have the potential to help with (1) understanding the climate change patterns of existing yield curves, and (2) development of mitigation and adaptation policies under scenarios of climate changes. This study indicates a general trend of tree-species response to climatic change, and its results should be interpreted with caution taking into account the limitations of model projections.

Modelling day-to-day stem diameter variation and annual growth of balsam fir ( Abies balsamea (L.) Mill.) from daily climate

In the present context of global climate changes and the continuous development of forest management strategies based on the concept of sustainable use, it is important to develop a better understanding of the climatic factors controlling the growth of boreal forests. In this study, we report the results of a five-year field research within which day-to-day balsam fir ( Abies balsamea (L.) Mill.) stem diameter variation was measured with dendrometers and examined in relation with various daily climatic variables. A model built with data from three growing seasons that included solar radiation, relative humidity, temperature and precipitation explained 84% of the variance in day-to-day stem diameter variation from June to September. The model has approximately the same predictive capability when validated with independent daily data from two other growing seasons. The model captured both the cumulative increment associated with the irreversible growth and the high frequency variation of day-to-day fluctuations associated to changes in the stem water content. In general, rainy days during which relative humidity was high and solar radiation was low favored stem diameter expansion (growth and swelling) while stem diameter decreased during periods of low relative humidity and high solar radiation. Similar models were obtained when the June–September period was divided into two parts (June–July and August–September) to better represent the period during which most of the cumulative annual stem increment is observed (June–July). Inter-annual variation in stem growth computed from the modeled day-to-day variation in stem diameter was significantly correlated to the inter-annual variation in annual growth determined from tree core measurements over a 10 year period ( p = 0.023). The model was notably able to capture a particularly poor growing year (2006) presumably due to a short-term heat stress period. Results suggest that the inclusion of daily data in growth–climate models may contribute to improve predictions of the potential tree growth response to climate by identifying particular climatic events that may escape to a classical dendroclimatic approach.

Growth patterns from different forest generations of Scots pine in Estonia

There is strong evidence that climate change alters tree growth in boreal forests. In Estonia, the analysis of ring measurements has been a common method to study growth changes. In this study, annual height growth data from dominant or co-dominant Scots pine (Pinus sylvestris L.) trees were used to develop a growth model for three forest generations. Stem analysis was applied and annual height growth was measured as the distance between whorls, as detected by branch knots of whorls on the split stem surface. Retrospective analysis of height growth produced comparative trends for three different age groups. Statistical analyses were used to estimate the impact of different factors on growth. Annual height growth was considered the best indicator for detecting possible trends in the growth potential of trees. Study results indicate that three generations (separated by time periods of 30–40 years) showed significant differences in growth patterns caused by shifts in climatic factors and management regimes (anthropogenic and natural disturbances).