Spruce Radial Growth Research Articles

Forward modelling of white spruce radial growth at trailing edge demonstrates high plasticity

Climate conditions throughout the 21st century across much of western Canada's boreal forest have been drier than normal leading to significant impacts on forest productivity and tree growth. Determining the limiting factors of radial growth in common boreal tree species under current and future conditions is crucial to reconcile how they will continue to respond to climate change. In this study, we used a network of 26 white spruce tree-ring chronologies south of its natural range as an artificially constructed trailing edge to assess climate-growth relationships and limiting factors by identifying seasonal climate relationships and using the Vaganov-Shashkin Lite (VS-Lite) model, respectively. Analysis revealed that white spruce in the study region is positively correlated to precipitation and negatively associated with temperature from the current and previous growing seasons. VS-Lite showed that moisture was the primary limiting factor in growth across the entire study area. The modelled radial growth from the VS-Lite model showed moderate success (14 of 26 site models were significant) and was more variable than measured tree-ring index values. The model systematically overestimated drought-related impacts on radial growth, especially during the middle portion of the growth season (June–August) indicating white spruce likely employs a conservative approach to carbohydrate storage as the region is much more susceptible to moisture deficits. The outcome of our research illustrates that white spruce may be resilient to hotter, drier conditions through environmental plasticity in the Boreal Plains.

Local Topography Has Significant Impact on Dendroclimatic Response of Picea jezoensis and Determines Variation of Factors Limiting Its Radial Growth in the Southern Sikhote-Alin

Climate change significantly influences forest communities, even leading to their complete transformation. In the case of boreal and temperate forests, it is particularly important to understand how dominant tree species respond to climate changes, as they largely determine the structure of forest communities. In this study, we focus on the Jezo spruce (Picea jezoensis (Siebold & Zucc.) Carriere), which is widespread in Northeast Asia. We investigated the climate parameters affecting the radial growth of Jezo spruce and how their influence changes along environmental gradients. For the research, 500 tree cores were collected from 10 sites located at elevations ranging from 460 to 1060 m. We found a negative response of Jezo spruce radial growth to precipitation in July–August and SPEI in July of the current year, maximum temperatures in July–August and November of the previous year. On the other hand, we observed a positive response to the maximum temperatures in January of the current year. Furthermore, we established that the influence of these climatic parameters depends on local topography, with 74.3% of the variance in response values being explained by elevation, slope, and the Topographic Position Index. The results obtained demonstrate that the reaction of Jezo spruce radial growth to climate change will be complex, and the balance between negative and positive effects will depend significantly on local topography.

Management can mitigate drought legacy effects on the growth of a moisture-sensitive conifer tree species

Understanding the impact of management upon post-drought tree growth recovery and drought legacy effects is among the fundamental challenges hindering the improvement of forest conservation strategies in the face of increasingly frequent, longer, and intensified extreme droughts under ongoing climate change. Yet surprisingly little is known to date about how management practices can influence drought legacy effects; and previous studies of management impacts on forest resilience to drought have reached inconsistent and contentious conclusions. This study sought to tackle these pressing questions and gain insight by analyzing tree-ring datasets from non-managed and managed Qinghai spruce forests in northwestern China. The results show improved growth resilience to drought of those trees under management practices. Moreover, Qinghai spruce radial growth in non-managed forest exhibited significant legacy effects of extreme drought, whereas such legacy effects were mitigated in managed forest. Nevertheless, both the resilience augmentation and the mitigation of drought legacy effects by management were much weaker in the face of a three-year persistent drought than a single-year event. Hence, we may conclude that current management practices are advantageous and necessary for forest conservation under exacerbated drought conditions, for which strategies and measures should be better thought out and tailored to specific situations, rather than being “one-size-fits-all”, to better serve the goals of forest managers and conservationists.

Радиальный рост ели (Picea abies (L.) Karst. × P. obovata Ledeb.) в условиях горных разработок

A dynamic of radial growth of spruce near a quarry of kimberlite pipes is investigated in this study. The quarry is considered as a potential source of anthropogenic impact. The research takes place at the central part of the White Sea Kuloi plateau, at the diamond deposit named after M.V. Lomonosov. The wood cores for dendrochronological analysis are from six trail plots located at different distances from the active quarry. The annual radial increment of spruce in all plots ranges from medium to high or very high. It is noticed that spruce trees have different durations of depression and expression cycles. The growth rates of the trees from the same plot do not coincide, or they show similarities to certain periods of tree’s life with cyclical patterns. In most cases, minimum and maximum extremes are observed near the well-known values of solar activity cycles. An inverse relationship is found between duration and repetition of the cycles. The measurements from all trail plots show a decrease in the amplitude of radial growth, which started in 2000. It took much greater extent in the period from 2010 to 2019. The samples of the spruce, which were taken from the oligotrophic habitats located near the quarry, indicate an increase of width of annual rings in the last 10–20 years. Fifty percent of them reveal a distinct radial extent. The trees from the most distant trail area are characterized by high simultaneity in the dynamics of the annual layers. Moreover, it is found a decrease in the maximum value of radial growth relative to the entire series of observations. Likewise, a reduce in the amplitude of increments is noted as a rise in the repeatability of relative growth indices below the regular values. It can be assumed that the change in the trend of radial growth in spruce in the oligotrophic habitats is mostly associated with the formation of а depression cone and, as a result, a general lowering of the groundwater level. For citation: Barzut O.S., Surso M.V. Radial Growth of Spruce (Picea abies (L.) Karst. × P. obovata Ledeb.) in the Conditions of Mining Impact. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 2, pp. 58–72. (In Russ.). https://doi.org/10.37482/0536-1036-2023-2-58-72

Space-Time Variability of the Climatic Signal in Spruce Radial Growth in the Pechora River Basin

Space-Time Variability of the Climatic Signal in Spruce Radial Growth in the Pechora River Basin

The Climate-Growth Relationship between Picea smithiana (Wall.) Boiss. and Abies pindrow (Royle ex D.Don) Royle along the Latitudinal Gradient in Northern Pakistan

A changing climate and global warming have adversely affected Pakistan’s moist and dry temperate vegetation. Abies pindrow (fir) (Royle ex D.Don) Royle and Picea smithiana (spruce) Wall.) Boiss are the two major representative species of the moist and dry temperate forests in Northern Pakistan. The dendroclimatic study of both species is crucial for the assessment of climate variability at various spatial and temporal scales. This study examined the dendroclimatology of fir and spruce, and analyzed the growth–climate relationship along the latitudinal gradient. Two hundred and nineteen samples (ring cores) of the two species were collected from five different sites (Shogran (SHG), Upper Dir (UDS), Bahrain Swat (BSG), Astore Gilgit (NPKA), and Sharan Kaghan (SHA)) in Northern Pakistan. The cores were cross-dated, and chronologies were generated for the species and climatic data (precipitation, temperature, and Palmer Drought Severity Index (PDSI)) correlated with radial growth. The interspecies correlations for fir were calculated as 0.54, 0.49, 0.52, 0.60, and 0.48 for SHG, UDS, BSG, NPKA, and SHA, respectively, whereas in the case of spruce, the interspecies correlations were 0.44 for SHG, 0.55 for UDS, and 0.49 for BSG. Climate variability was observed in the samples of both species, which showed significant drought and humid years at specific intervals. With respect to the correlation between tree-ring width and climatic factors, a positive correlation was observed between fir growth and summer season precipitation, mean temperature, and PDSI in the spring, summer, and autumn seasons. Similarly, the growth of spruce was positively correlated with precipitation (in February, September, and May) and PDSI (in the summer and autumn seasons); however, no correlation was observed between monthly temperature and spruce growth. The relationship of fir and spruce growth with seasonal precipitation and PDSI showed a change from a negative to a positive correlation after 1980, following rapid warming. During the winter and spring, the correlation coefficient between fir radial growth and seasonal temperature showed an initial upward trend followed by a progressive decrease along with increasing latitude. Seasonal variations were observed regarding the correlation coefficient between spruce radial growth and increasing latitude (increasing in winter; a decreasing trend in spring and summer; an initial increase and then a decrease in autumn). In the same way, the correlation of seasonal temperature and PDSI with the radial growth of both species showed increasing trends with increasing latitude, except in the autumn season.

Priraščanje navadne smreke (Picea abies (L.) Karst.) in evropskega macesna (Larix decidua Mill.) na nekdanjih novinah v koprivni v Karavankah

Based on previous measurements from 1962 to 2017 on forest research plots located on former slash-and-burn farming areas in the cadastral municipality of Koprivna, the diameter and height increment as well as volume increments of the two main tree species - spruce and larch - were calculated. These set-aside natural research plots have a smaller mean basal area diameter, but the number of trees is higher than in comparable managed forests. Due to the high-density of tree stands over the past thirty years, radial increment of spruce and larch has declined. To determine the influence of environmental factors on radial growth of spruce and larch, a dendrochronological analysis was conducted. According to the dendrochronological analysis of radial increment of trees, the number of years with a negative response has been higher since 1984.

Radial growth of Scots pine and Norway spruce stands as an indicator of soil and environmental conditions

The study presents an analysis of radial growth of Scots pine and Norway spruce trees growing on drained soils formed on varved clays at the sample sites of the Lisino Experimental Forestry (Lisino). Based on dendrochronological studies in Lisino, it has been found that the radial growth of Scots pine and Norway spruce is a sensitive indicator of changes in the soil water regime, climate, and phytocenotic relationships. On the basis of the character of tree-ring width growth, the growth charts allowed distinguishing zones with close to average growth values, as well as with increased and decreased values of radial growth. The cyclical pattern of tree ring width is well expressed in the successive change of zones. The availability of dendrochronological research materials with precise spatial and temporal reference makes it possible to organize monitoring of radial growth of trees as an indicator of changes in climate and habitat conditions.

Is the Radial Growth of Irrigated Urban Trees More Strongly Correlated to Light and Temperature than Water?

Background: Real-time monitoring of tree growth can provide novel information about trees in urban/suburban areas and the myriad ecosystem services they provide. By monitoring irrigated specimen trees, we tested the hypothesis that in trees with sufficient water, growth is governed by environmental factors regulating energy gain rather than by factors related to water use. Methods: Internet-enabled, high-resolution dendrometers were installed on 3 trees in Southampton, NY, USA. The instruments, along with a weather station, streamed data to a project web page that was updated once an hour. Growing periods were determined using a Hidden Markov Model based on a zero-growth model. Linear models and conditional inference trees correlated environmental variables to growth magnitude and rate of growth. Results: Growth was governed by the interacting environmental variables of air temperature, soil moisture, vapor pressure deficit (VPD), and took place primarily at night. Radial growth of spruce began April 14 after the accumulation of 69.7 °C growing degree days and ended September 7. Cedar growth began later (April 26) after the accumulation of 160.6 °C and ended later (November 3). During the observation period, these 3 modest suburban trees sequestered 115.1 kg of CO2. Conclusions: Though irrigated, residential tree growth in our experiment was affected by environmental factors relating to both water use and energy gain through photosynthesis. Linking tree growth to fluctuations in environmental conditions facilitates the development of a predictive understanding useful for ecosystem management and growth forecasting across future altering climates.

Divergent responses to permafrost and precipitation reveal mechanisms for the spatial variation of two sympatric spruce

AbstractThe ranges of black and white spruce are largely sympatric, suggesting both species have similar climate requirements. The two species, however, are highly segregated across the landscape with black spruce most common on nutrient‐poor sites with cold, poorly drained soils and white spruce more common on productive sites with warmer, well‐drained soils. Because site conditions influence tree climate–growth responses, it is difficult to compare white and black spruce climate–growth responses as these responses are confounded by the differences in site conditions in which the two species naturally occur. As the climate warms dramatically in northern latitudes, it is critical to understand how a changing climate and associated changes in permafrost and fire regimes will interact to shape future species composition and ecosystem functioning in the boreal forest. In this study, we examined the climate–growth responses of black and white spruce growing in the same sites. This approach eliminates the confounding factor of site conditions and facilitates our understanding of how these two species respond to climate. We included standardized thaw depth of the active layer in our analysis as a representation of permafrost, which is a key factor delineating these two species' habitat preferences and is actively warming and thawing as the climate warms. Our most important finding was that the climate–growth responses of the two species, but especially white spruce, hinged on the thaw depth of the active layer. Specifically, with increasing June–July temperatures white spruce radial growth increased in areas with deep thaw or no near‐surface permafrost, but strongly decreased when growing in areas with near‐surface permafrost. Black spruce radial growth was less sensitive to June–July temperature than white spruce but had a consistent and more positive response to summer precipitation. These findings point to a primary mechanism potentially driving the positioning of these two tree species within the landscapes of boreal interior Alaska and imply widespread thawing of permafrost may foster expansion of white spruce in this region at the expense of black spruce, but that in a wetter climate, black spruce may gain competitive advantage over white spruce in some landscape positions.

Formation and structure of wood and phloem in Norway spruce

Wood and phloem formation databases are important for understanding the effects of climate change and extreme weather events on species composition, tree vitality, wood production and wood quality in Slovenian forests. In this paper, we present the latest results on the radial growth of Norway spruce (Picea abies (L.) Karst.) at two sites in Slovenia, Panška reka (PAN – 400 m a. s .l.) and Menina planina (MEN – 1200 m a. s .l.) in 2009–2011. The focus was on the seasonal dynamics of early and latewood, and early and late phloem formation. We found that site conditions greatly affected the seasonal dynamics of wood and phloem formation, which was reflected in the width and structure of annual increments. At the higher elevation MEN site, the growing season was about a month shorter (about 4 months long), which resulted in 39% and 15% narrower wood and phloem increments, respectively. At MEN, the transition from early to latewood was observed on average only a week later than at PAN, while the transition from early to late phloem occurred on average 20 days later at MEN than at PAN. Information on the impact of site conditions on radial growth of spruce and wood quality is important for all stakeholders in the forest-wood value chain, as it can help to take appropriate management measures of adaptation to changing conditions.

Lodgepole pine and interior spruce radial growth response to climate and topography in the Canadian Rocky Mountains, Alberta

Climate change may have spatially variable impacts on growth of trees in topographically diverse environments, making generalizing across broad spatial and temporal extents inappropriate. Therefore, topography must be considered when analyzing growth response to climate. We address these topo-climatic relationships in the Canadian Rocky Mountains, focusing on lodgepole pine (Pinus contorta Douglas ex Louden) and interior spruce (Picea glauca (Moench) Voss × Picea engelmannii hybrid Parry) growth response to climate, Palmer drought severity index (PDSI), aspect, and slope angle. Climate variables correlate with older lodgepole pine growth on south- and west-facing slopes, including previous August temperature, winter and spring precipitation, and previous late-summer and current spring PDSI, but younger lodgepole pine were generally less sensitive to climate. Climate variables correlate with interior spruce growth on all slope aspects, with winter temperature and PDSI important for young and old individuals. Numerous monthly growth–climate correlations are not temporally stable, with shifts over the past century, and response differs by slope aspect and angle. Both species are likely to be negatively affected by moisture stress in the future in some, but not all, topographic environments. Results suggest species-specific and site-specific spatiotemporally diverse climate–growth responses, indicating that climate change is likely to have spatially variable impacts on radial growth response in mountainous environments.

Multi-year white spruce drought legacies in southern Saskatchewan

In many regions across western Canada’s boreal forest, drought impacts on long-term white spruce (Picea glauca (Moench) Voss) radial growth are poorly understood. This is also the case for white spruce shelterbelt trees south of their natural range in agricultural regions of the Canadian Prairies. Understanding how white spruce has responded to drought in the past will be vital for management purposes for those who rely on shelterbelts and will help develop a better understanding of how white spruce in the Canadian Boreal Forest will be impacted by climate change. Using tree-rings, we tested how radial growth responds to different drought magnitudes, time-steps, and timing in southern Saskatchewan during and after droughts. White spruce radial growth is statistically associated to 3-month June-August and July-September Standardized Precipitation-Evapotranspiration Index (SPEI) values. Drought severity has a greater impact on radial growth compared to timing and time-step during the drought year and the five years after. Three-month, extreme droughts from July-September appear to have the greatest overall negative impact on white spruce growth in southern Saskatchewan. Our results indicate that white spruce has a complex multi-year response to varying drought conditions in southern Saskatchewan although the physiological mechanisms behind radial growth changes are yet unknown. This research augments our current understanding of white spruce’s drought-growth relationship and provides new information useful for understanding how the shelterbelts in southern Saskatchewan and the Canadian Boreal Forest may respond to different characteristics of moisture deficit conditions in the future where longer and more pronounced droughts are projected to occur.

Mixed vs. monospecific mountain forests in response to climate change: structural and growth perspectives of Norway spruce and European beech

Mixed forests play a key role in terms of stability, production potential and adaptation to climate change. Norway spruce [PA, Picea abies (L.) Karst] and European beech (FS, Fagus sylvatica L.) are among the most important tree species in Europe. The aim of the study was to determine the influence of the species composition of these two tree genera on the production, structure, diversity and growth of mixed Fageto-Piceetum acidophilum stands in the Krkonoše Mountains, in the Czech Republic. The following 5 variants (ratios) of mixture were compared in 6 replications (30 research plots in total): PA 100%, PA 75:25 FS, PA 50:50 FS, PA 25:75 FS and FS 100%. Based on 178 tree core samples, the research also focused on the influence of climatic factors (temperature, precipitation) and air pollution (SO2, NOX, AOT40F) on the radial growth of these tree species of particular variants. Mixed forests showed a timber production higher by 7.7% (-10.8 to 31.5%) in comparison to spruce monocultures, and by 47.3% (21.9–79.7%) compared to beech monocultures. The largest production as well as the highest diameter increment were documented in PA 75:25 FS (656 m3 ha−1). In addition, this variant had the lowest extreme decreases/fluctuations in radial growth in both tree species. Over the last 50 years, the increment in beech increased by 7.9% and by 2.5% in spruce. The cyclical behavior in the radial growth of both tree species occurred in the short-term solar cycles of 9–11 and long-term periods of 50–75 years, while the spruce showed higher cyclic intensity. The concentration of both SO2 and NOX had a significant negative effect on the radial growth of spruce. In both tree species, the negative effect of air pollution lessened with their decreasing share in the stand. Similarly, precipitation and temperature had a more significant effect on the growth of monospecific variants in both tree species, especially in beech. Temperatures, when compared to precipitation, had a greater effect on the radial growth of both tree genera, especially during the vegetation period. In terms of diversity, mixed stands achieved significantly higher structural (diameter, height, crown) differentiation and overall diversity compared to monospecific variants. In general, mixed stands can achieve higher production potential, diversity and especially resistance to climate extremes and air pollution in relation to climate change in the water-sufficient highland and mountain areas of the Czech Republic. Differences between mixed stands vs. monocultures, i.e. the effect of tree species mixing, depend on suitable ratios of tree species and their spatial pattern.

Impacts of Climatic Variation on the Growth of Black Spruce Across the Forest-Tundra Ecotone: Positive Effects of Warm Growing Seasons and Heat Waves Are Offset by Late Spring Frosts

Climate strongly limits the physiological processes of trees near their range limits, leading to increased growth sensitivity. Northeastern North America is experiencing considerable warming, so the growth of trees near the northern treeline represents a key indicator of forest responses to climate change. However, tree-ring series and corresponding climatic data are scarce across the forest-tundra ecotone when compared to southern boreal regions, resulting in fewer studies on growth-climate relationships focused on this ecotone. Using daily climatic data, we identified trends in growing season heat accumulation and the intensity of acute climatic events over the last several decades in the southern and the northern parts of the forest-tundra ecotone in northeastern North America, and investigated their influence on black spruce radial growth. We found that black spruce trees responded positively to the increase in growing season temperatures and heat wave intensity, suggesting that growth is currently limited by suboptimal temperatures. While tree growth in the southern region generally benefited from warm spring temperatures, vulnerability to late spring frosts reduced tree growth in the northern region and increased probability of abrupt growth decline. In this region, late spring frosts offset approximately half of the additional growth that would otherwise occur over the course of a warm growing season. This vulnerability of northern trees may result from local adaptations to short growing seasons, which initiate biological activities at colder temperatures in the spring. Overall, our results highlight the need to explicitly incorporate acute climatic events into modeling efforts in order to refine our understanding of the impact of climate change on forest dynamics.

Радіальний приріст ялини європейської (Picea abies L.) в осередку її всихання (Горгани, Українські Карпати)

Упродовж останніх років відбувається інтенсивне всихання ялинових лісів в Українських Карпатах. Цей процес завдає економічних збитків, призводить до погіршення життєвого стану ялинників та зниження рівня надання екосистемних послуг лісами. Для встановлення щорічного радіального приросту ялини європейської та його динаміки, а також подальшого обґрунтування лісівничих заходів у гірському масиві Горган у дуже ослаблому за санітарним станом та складним за структурою мішаному деревостані в 2019 р. здійснено дендрохронологічні дослідження. Виявлено стрімке зниження приросту ялини, починаючи із першого класу віку, яке може бути пов'язане (окрім інших факторів) із міжвидовою конкуренцією (ялини і ялиці). Середній приріст деревостану за досліджуваний період становить 1,97 мм/рік. Найменші радіальні прирости ялини (1,05 мм/рік) були в 1980–2000 рр., коли деревостан проходив стадію розладнання. За останні 20 років середній приріст дещо збільшився (1,19 мм/рік), очевидно, внаслідок розрідження деревостану. Коливання відносних індексів приростів знаходяться в межах 84,24–115,52 %. Середня тривалість циклів приростів 8 років. Починаючи із середини ХХ ст., частота коливань приростів збільшилася, а отже, умови середовища стали екстремальнішими для росту ялини. Теперішній склад підросту свідчить про те, що в майбутньому на дослідному об'єкті відбудеться зміна біоценозу. Під час дендрохронологічних досліджень в осередках всихання ялини, необхідна різнобічна інформація про природні й антропогенні фактори, які можуть впливати на радіальний приріст дерев та його мінливість.

Effect of climate and air pollution on radial growth of mixed forests: Abies alba Mill. vs. Picea abies (L.) Karst.

Abstract Norway spruce (Picea abies [L.] Karst.) and silver fir (Abies alba Mill.) are main tree species of Central Europe that are currently highly vulnerable in times of global climate change. The research deals with the effect of climate and air pollution on radial growth of silver fir and Norway spruce in mixed age-varied (56 – 146 years) forests in the Jeseníky Protected Landscape Area, the Czech Republic. The objectives were to evaluate biodiversity, structure and production, specifically interaction of radial growth of fir and spruce to air pollution (SO2, NOX, tropospheric ozone) and climatic factors (precipitation, air temperature). Concentration of SO2 and NOX had negative effect on radial growth of fir, while radial growth of spruce was more negatively influenced by tropospheric ozone. Fir showed higher variability in radial growth and was more sensitive to climatic factors compared to spruce. On the other hand, fir was relatively adaptable tree species that regenerated very well when the pressure of stress factors subsided (air pollution load, Caucasian bark beetle, frost damage). Low temperature was a limiting factor of radial growth in the study mountainous area, especially for fir. Fir was significantly sensitive to late frost, respectively, spruce to winter desiccation and spring droughts with synergism of air pollution load. Generally, older forest stands were more negatively influenced by air pollution load and climatic extremes compared to young trees.

Adaption of Norway spruce and European beech forests under climate change: from resistance to close-to-nature silviculture

Abstract In time of climate change, close-to-nature silviculture is growing in importance as a tool for future forest management. The paper study the tree layer and natural regeneration of monospecific Norway spruce (Picea abies [L.] Karst.), trough mixed spruce-beech to dominant European beech (Fagus sylvatica L.) forests in Jizerské hory Mts., the Czech Republic. In the locality, shelterwood and selection system have been applied since 2000. The research objectives were to evaluate production parameters, structural diversity, species richness, natural regeneration dynamics and radial growth of individual tree species in relation to climatic factors and air pollution. The stand volume on permanent research plots amounted to 441 – 731 m3 ha−1 in initial stage of transformation. Natural regeneration showed high expansion of beech and decrease of spruce compared to mature tree species composition. Radial growth of spruce was in significant negative correlation with SO2 and NOX concentrations compared to no effect on beech increment. Moreover, spruce was more sensitive to significant years with extreme low radial growth. Beech was more stable in radial growth. Spruce was more resistant to air pollution and climatic stress in mixed stands. Low temperature was limiting factor of radial growth together with climate extremes (such as strong frosts and more frequent droughts) and biotic factors (bark beetle, beech scale). Close-to-nature management supporting admixed tree species should lead in future to diversification of stand structure toward higher species, spatial and age structure to mitigate negative effect of climatic change.

Interspecific difference of relationship between radial growth and climate factor for Larix olgensis and Picea jezoensis var. komarovii in Changbai Mountain, Northeast China.

To clarify the responses of radial growth of different tree species to climate change and its stability, we explored the relationships between radial growth and climate factors of larch (Larix olgensis) and spruce (Picea jezoensis var. komarovii) distributed at high altitude (1600-1750 m) on the northern slope of Changbai Mountain, using the chronological method. The results showed that the growth of larch was significantly positively correlated with the maximum temperature in June and negatively correlated with the precipitation in June. The radial growth of spruce was significantly positively correlated with the maximum temperature in May. Results from redundancy analysis showed that larch growth was mainly affected by summer temperature, while spruce growth was significantly restricted by spring temperature. During 1959-2014, the relationship between larch growth and summer temperature was relatively stable. For spruce, the correlation between radial growth and spring temperatures had gradually weakened since 1986, mainly due to the growth slowdown because of decreased maximum air temperature. Our results provide theoretical references for predicting the growth response of conifers at Changbai Mountain region in the context of climate change.

The influence of atmospheric emissions from Arkhangelsk pulp and paper mill on radial growth of spruce

Spruce is sensitive to atmospheric pollution and can serve as a bioindicator of environmental quality. Dendrochronological studies revealed no significant changes in the radial growth of spruce in the zone of influence of the Arkhangelsk PPM. Correlation coefficients between the total annual emissions of the Arkhangelsk PPM into the atmosphere and the values of the radial annual growth of individual trees during the period from 2001 to 2016 did not prove the connection between them, both when comparing these parameters in the year of the event and with the delay for the year.