Search Results (127)

Against the background of global warming, forests across environmental gradients show distinct responses to climate change, necessitating research on tree growth patterns under specific conditions. Climate and competition are critical factors affecting tree growth, yet their combined effects across altitudinal gradients remain unclear, especially in arid regions such as Central Asia. This study investigated how climate and competition influence radial growth of Picea schrenkiana Fisch. et C.A.Mey. across altitudinal gradients (1500–2670 m) in the Middle Tianshan Mountains. Using dendroclimatology, competition indices, multivariate statistical analyses, and nonlinear models across 12 plots, we examined spatial variability in growth responses. Results revealed significant altitudinal differences in growth responses to climate and competition across altitudes. At low elevations, growth is primarily limited by water availability; drought indices and spring precipitation exert positive effects, while high temperatures inhibit growth. At mid-elevations, climate becomes the dominant driver, particularly spring temperature and precipitation playing key roles, while competition has no significant effect. At high elevations, temperature becomes the primary driver of growth; however, the overall sensitivity to climate is reduced compared to lower elevations. Multiple regression analyses confirm that water-related factors drive growth at lower and middle elevations, whereas temperature is the primary driver at higher elevations. Further model comparison indicates that while nonlinear models performed slightly better at mid-elevations, linear approaches similarly provided interpretable climate–growth relationships. This study demonstrates significant spatial variation in growth determinants, with water-driven controls dominating at lower elevations and competition effects ranging from significant to non-significant as altitude increases. Future warming may further intensify drought stress at lower elevations, and whether or not the weak positive responses currently observed at higher elevations will persist remains uncertain. These findings provide a scientific basis for sustainable management of arid mountain forests under climate change. Full article

With the intensification of global climate change and human activities, coniferous species as the main components of natural forests in the Altay Mountains are facing the challenges of aging and regeneration. This study systematically analyzed structural heterogeneity and regeneration of three coniferous stand groups, Larix sibirica Ledeb. stand group, Abies sibirica Ledeb.-Picea obovata Ledeb.-Larix sibirica mixed stand group, and Picea obovata stand group, respectively, across western, central, and eastern forest areas of the Altay Mountains in Northwest China based on field surveys in 2023. Methodologically, we integrated Kruskal–Wallis/Dunn’s post hoc tests, nonlinear power-law modeling (diameter at breast height (DBH)–age relationships, validated via R², root mean square error (RMSE), and F-tests), static life tables (age class mortality and survival curves), and dynamic indices. Key findings revealed structural divergence: the L. sibirica stand group exhibited dominance of large-diameter trees (>30 cm DBH) with sparse seedlings/saplings and limited regeneration; the mixed stand group was dominated by small DBH individuals (<10 cm), showing young age structures and vigorous regeneration; while the P. obovata stand group displayed uniform DBH/height distributions and slow regeneration capacity. Radial growth rates differed significantly—highest in the mixed stand group (average of 0.315 cm/a), intermediate in the P. obovata stand group (0.216 cm/a), and lowest in the L. sibirica stand group (0.180 cm/a). Age–density trends varied among stand groups: unimodal in the L. sibirica and P. obovata stand groups while declining in the mixed stand group. All stand groups followed a Deevey-II survival curve (constant mortality across ages). The mixed stand group showed the highest growth potential but maximum disturbance risk, the L. sibirica stand group exhibited complex variation with lowest risk probability, while the P. obovata stand group had weaker adaptive capacity. These results underscore the need for differentiated management: promoting L. sibirica regeneration via gap-based interventions, enhancing disturbance resistance in the mixed stand group through structural diversification, and prioritizing P. obovata conservation to maintain ecosystem stability. This multi-method framework bridges stand-scale heterogeneity with demographic mechanisms, offering actionable insights for climate-resilient forestry. Full article

A deeper understanding of growth–climate relationships in natural forests (NFs) and planted forests (PFs) is crucial for the prediction of climate change impacts on forest productivity. Yet, the mechanisms and divergences in climatic responses between these forest types remain debated. This study investigated P. tabulaeformis NFs and PFs in China using tree-ring chronologies to analyze their radial growth responses to climatic factors and associated temporal–spatial dynamics. The results reveal significant negative correlations between radial growth and mean temperatures (Tmean) in August of the previous year and June of the current year, and positive correlations were observed with the September standardized precipitation evapotranspiration index (SPEI) of the previous year and May precipitation (PPT) and SPEI of the current year. Compared with NFs, PFs exhibited a heightened climatic sensitivity, with stronger inhibitory effects from prior- and current-year growing-season temperatures and greater SPEI influences during the growing season. Moving window analysis demonstrated higher temporal variability and more frequent short-term correlation shifts in PF growth–climate relationships. Spatially, NFs displayed latitudinal divergence, autumn Tmean shifted from growth-suppressive in southern regions to growth-promotive in the north, and winter SPEI transitioned from positive to negative correlations along the same gradient. However, PFs showed no significant spatial patterns. Relative importance analysis highlighted water availability (PPT and SPEI) as the dominant driver of NF growth, whereas temperature, moisture, and solar radiation co-regulated PF growth. These findings provide critical insights into climate-driven growth divergences between forest types and offer scientific support for the optimization of NF conservation and PF management under accelerating climate change. Full article

Climate change has affected forest ecosystems across the world over the past century. However, its impact is particularly high in the Himalayas due to increasing temperatures, extreme precipitation events, and regional droughts. In this context, a review of the current stage of research was deemed necessary to understand the adaptation of a key conifer species to climate variability in the Central Himalayas. Hence, we conducted a systematic review of published peer-reviewed journal articles addressing the growth performance of Abies spectabilis (D. Don) Spach in the Central Himalayas. From this review, three main patterns of climate response have emerged: a positive correlation of radial tree growth with temperature of the current and previous growing seasons, tree growth limitation by winter temperature, and by temperature or moisture in the pre-monsoon season. Overall, results indicate an elevation-dependent temperature sensitivity, a crucial role of moisture availability, and seasonal shifts in climate–growth relationships, reflecting the species’ adaptability to changing climate conditions. Our review revealed that studies on elevation-dependent adaptation of wood anatomical traits by A. spectabilis are still rare. The tree-ring growth of this species shows a complex response to climate variability, with increasing as well as decreasing growth trends across its distribution range. Full article

Climate change may induce regional climate shifts, profoundly affecting plant growth, distribution, and ecosystems. This study collected 37 Sabina chinensis (Sabina chinensis (L.) Ant. cv. Kaizuca) tree cores (74 samples) from a site in the Yangtze River Delta (YRD) coastal region. Utilizing traditional dendrochronological principles and methods, a standardized tree-ring width chronology was developed to detect climate shift points and explore the differences in Sabina chinensis radial growth responses to climate factors, before and after these shifts. The findings are as follows: (1) Between 1967 and 2020, temperature emerged as the main climate factor influencing the radial growth of Sabina chinensis in the study area. (2) There are differences in the correlations between the tree radial growth of Sabina chinensis and climate factors in different months and seasons, before and after climate change. (3) Moving correlation analysis indicated that the relationships between radial growth and precipitation and temperature gradually altered. The study reveals the intricate influencing mechanisms of different climate factors on Sabina chinensis radial growth, before and after climate shifts, offering valuable references for other similar dendrochronological studies. Full article

Swiss stone pine (Pinus cembra L.) may represent a vital species for afforestation at the upper altitudinal limits of forests due to its adaptability to challenging environmental conditions. In this study, we aimed to analyze the variability in ring width (radial growth, RW, earlywood, EW, latewood, LW, and latewood proportion, LWP) and the influence of different sites on the climatic resilience of twelve European provenances of Swiss stone pine to identify the best-adapted provenances. Five provenances from the Alps and seven from the Carpathians were tested across two 27-year-old field trials conducted in the Eastern and Southern Carpathians. Moderate genetic differentiation among the provenances was noted, which could ensure the success of breeding programs. Based on ring width and latewood proportion, we successfully selected the 25% best-performing provenances and recommend them for use in the provenance regions where have performed. The significant influence of the testing site and the different outcomes of the provenances necessitate extreme attention during the transfer of forest reproductive materials. Additionally, the breeding strategies applied in the two trials differed, consisting in individual selection in the Cugir trial and provenance selection in the Cârlibaba trial. The low resistance of all provenances shown in both trials, particularly in the Cugir trial, is worrying in the context of global warming. Full article

Yunnan is located in the southwestern part of China, with rich tea tree germplasm resources and diversified geomorphological and climatic features, which help us to carry out research related to tea tree chronology and provide scientific and effective support information for enriching the database of tree rings in western Yunnan. This study took the Brown Mountain tea tree in Xishuangbanna as the research object, collected tea tree sample cores through tree growth cone sampling, measured the width of the annual rings, cross-dated them, and established a chronology of the width of the annual rings of the tea tree. The R language was used to analyze the response function of the tea tree’s annual ring chronology with the climatic factors of the study site, discussed the relationship between the radial growth of the tea tree in subtropical regions and climatic factors, and determined the main factors that affected the radial growth of the tea tree. The results of the study showed that the chronology of the tea tree’s whorl width spanned 70 years (1954–2023), with an average annual growth rate of 1.283 mm/year; the average sensitivity was 0.514, which indicated that the chronology contained richer climatic information. The representativeness of the sample group of the whorl width index (EPS) was 0.716, indicating that the consistency of the growth inter-annual variations was better among the different trees. The radial growth was correlated with climatic factors such as temperature and moisture; the radial growth of the tea tree was usually more sensitive to moisture availability, limited by hydrological and climatic factors throughout the rainy season of the year, and positively correlated with the temperature in summer and autumn. In terms of the stability of the radial growth of the tea tree in relation to the climatic response, the growth of the tea tree in the study area may have benefited from future warming of the climate and reduction in precipitation. Full article

Forest health monitoring is crucial for sustainable management, especially with the challenges posed by climate warming. Remote sensing data provide vegetation indices, such as the Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI), that are widely used in assessing forest health. However, studies considering the validation of these data with field assessments of tree vigor are still scarce. To address this issue, we explored the relationships in declining (D) and non-declining (N) silver fir (Abies alba Mill.) stands from the Spanish Pyrenees between changes in canopy (a proxy of vigor), vegetation indices (NDVI, EVI) and climate variables. We compared trends in the NDVI and EVI for the period of 1984–2023 for D and N stands showing high and low crown defoliation levels, respectively. The EVI values allowed for the separation of stands according to their vigor earlier and more clearly than NDVI values, which did not show clear patterns throughout the time series. Significant negative correlations were found between the EVI and stand defoliation (r = −0.57) or mean radial growth (r = 0.81). Late-spring drought reduced the EVI. The EVI series reflected similar spatial patterns in terms of stand defoliation and tree growth, offering complementary information, along with the strengths of remote sensing with respect to its spatial and temporal coverage, for the early detection of forest dieback. This study also contributes to a better understanding of remote sensing indices, which is useful for forest health monitoring. Full article

Understanding how forest ecosystems respond to climate variability is critical for predicting the impacts of climate change on semi-arid and temperate regions. This study examines the climatic drivers of radial growth in Larix sibirica Ledeb in the Kanas Lake region, northern Xinjiang, China, to explore how climate change may alter forest growth patterns. Using tree-ring chronologies, we examine the relationships between temperature, precipitation, and drought conditions, as well as the influence of large-scale atmospheric circulation patterns on growth. Results indicate that high summer temperatures negatively affect tree growth, while adequate precipitation plays a crucial role in mitigating water stress, especially during key growth periods. Positive correlations with the Palmer Drought Severity Index further underscore the importance of long-term moisture availability. Moreover, the study highlights the role of the El Niño-Southern Oscillation in influencing moisture transport, with significant correlations between sea surface temperatures in the Niño 4 region and tree-ring growth. Future growth simulations under two climate scenarios suggest that moderate warming (SSP 2–4.5) may enhance growth, while more extreme warming (SSP 5–8.5) introduces greater uncertainty and potential growth instability. These findings provide critical guidance for forest management strategies in the face of climate change. Full article

The overall objective of our study was to examine the influence of climatic factors and tree-based competition on the radial growth of jack pine (Pinus banksiana) forests affected by the fungal pathogen, Diplodia pinea. Our study utilized dendroclimatic techniques to examine how past annual diameter growth can be influenced by the historical climate of the region. Twenty jack pine sites were sampled in Michigan within the Upper Peninsula (UP) and the Lower Peninsula (LP) region. Furthermore, two condition levels of forest health (D. pinea-affected vs. healthy reference stands) were considered between two levels of stand density (i.e., high vs. low density). The relationships between radial growth and climate identified in this study indicated that jack pine radial growth was typically affected by the climatic moisture index, whereas the response to temperature variables was weak to non-existent. In the Upper Peninsula region, crown damage likely sustained during harsh winters could have made jack pine stands prone to D. pinea by facilitating a point of entry for infection; furthermore, higher-density stands infected by D. pinea were influenced by moisture stress that occurred during the summer of the prior year. In the LP region, regardless of stand density, D. pinea was sensitive to moisture stress in the summer of the prior growing season; furthermore, negative relationships with precipitation in the spring may have improved spore dispersion in D. pinea-affected stands. Overall, our study provides improved understanding of the interactive role of climatic stress and forest pathogens on jack pine productivity. Full article

Fires affect forest dynamics in seasonally dry regions such as the Mediterranean Basin. There, fire impacts on tree growth have been widely characterized in conifers, particularly pine species, but we lack information on broadleaf tree species that sprout after fires. We investigated post-fire radial growth responses in two coexisting Mediterranean hardwood species (the evergreen Quercus ilex, the deciduous Celtis australis) using tree-ring width data. We compared growth data from burnt and unburnt stands of each species subjected to similar climatic, soil and management conditions. We also calculated climate–growth relationships to assess if burnt stands were also negatively impacted by water shortage, which could hinder growth recovery. Tree-ring data of both species allowed us to quantify post-fire growth enhancements of +39.5% and +48.9% in Q. ilex and C. australis, respectively, one year after the fire. Dry spring climate conditions reduced growth, regardless of the fire impact, but high precipitation in the previous winter enhanced growth. High June radiation was negatively related to the growth of unburnt Q. ilex and burnt C. australis stands, respectively. Post-fire growth enhancement lasted for five years after the fire and it was a transitory effect because the growth rates of burnt and unburnt stands were similar afterwards. Full article

Forests are critical in regulation of carbon and water cycles and mitigation of climate change. Forest water-use efficiency (WUE) refers to the ratio of biomass produced (or assimilated carbon) to the amount of water used by forests, which indicates how effectively a forest utilizes water to achieve productivity. Climate change and its impact on forest WUE are important research directions that explore the complex relationship between global environmental change and the forest ecosystem dynamics. The global intensification of climate change underscores the need for an inclusive understanding of forest water use and makes it crucial to know how forests balance carbon and water resources, which is essential for effective forest management and predicting ecosystem responses to climate change. This study aims to comprehensively and objectively analyze current research trends and future directions related to the response of forest WUE to climate change. Our database included 1755 research papers from the Web of Science Core Collection, spanning from 2000 to 2023. Our analysis included cooperative networks of countries, authors, and institutions, as well as the most frequently cited journals and articles, keyword co-occurrence analysis, and a keyword burst analysis. The results showed that the top cooperative country, author, and institution is PR China, Prof. Dr. Jesús Julio Camarero from the Consejo Superior de Investigaciones Científicas (CSIC), and the Chinese Academy of Sciences, respectively. The leading journal in this field is “Global Change Biology”. Critical research hot topics include gas exchange, modeling, altitudinal gradients, tree growth dynamics, net carbon exchange, global change drivers, tropical forests, nitrogen stoichiometry, Northern China plains, and extreme drought conditions. Frontier topics that have emerged in recent years include studies on China’s Loess Plateau, stable isotopes, radial growth, gross primary productivity, and Scots pine. The insights from this analysis are vital for researchers, decision-makers, and forestry professionals aiming to mitigate the impacts of climate change on forest WUE and overall ecosystem health and resilience. This study emphasizes the importance of sustained research efforts and global research collaboration in addressing the intricate challenges posed by climate change to forest ecosystems. Full article

Pollarding has historically been used in broadleaf tree species across European woodlands. However, despite pollarding enhances vigor growth in the short term, it is still unclear how long this effect lasts and whether it can alleviate drought stress in seasonally dry regions. We compared the radial growth and wood δ¹³C (¹³C/¹²C), a proxy of intrinsic water-use efficiency (iWUE), of trees pollarded 10 and 20 years ago in two black poplar (Populus nigra L.) riparian stands located in North Eastern Spain and subjected to different ecohydrological conditions. We also assessed if pollarded trees showed different leaf phenology as compared with uncut trees of coexisting white poplar (Populus alba L.) trees. The relationships between growth, climate variables, drought severity and river flow were quantified. Pollarded and uncut trees showed a similar leaf phenology with a trend towards earlier leaf unfolding as springs become warmer. Pollarding increased growth rates by 54% (ratio between trees pollarded 10 and 20 years ago, respectively), but this enhancement was transitory and lasted ca. 10 years, whereas wood δ¹³C decreased −5%. The growth of black poplar increased in response to high precipitation in the previous winter, cool wet conditions, and a higher river flow in summer. Pollarding improves growth and relieves drought stress. Full article

Pinus pinea is an important Mediterranean species due to its adaptability and tolerance to aridity and its high-quality pine nuts. Different forest types located in Mediterranean native and non-native environments provide the opportunity to perform comparative studies on the species’ response to climate change. The aims of this study were to elucidate growth patterns of the species growing in native and exotic habitats and to analyze its response to climatic fluctuations, particularly drought, in both geographical contexts. Understanding stone pine (Pinus pinea) growth responses to climate variability in native and exotic habitats by comparing natural stands and plantations may provide useful information to plan adequate management under climate change. By doing so, we enhance the understanding of P. pinea’s adaptability and provide practical approaches to its sustainable management. In this study, we reconstructed and compared the stem radial growth of seven stone pine stands, two in southern Spain and five in central–southern Chile, growing under different climatic conditions. We quantified the relationships between growth variability and climate variables (total rainfall, mean temperature, and SPEI drought index). Growth was positively correlated with autumn rainfall in plantations and with autumn–winter rainfall in natural stands. Growth was also enhanced by high autumn-to-spring rainfall in the driest Chilean plantation, whereas in the wettest and coolest plantation, such correlation was found in winter and summer. A negative impact of summer temperature was found only in one of the five Chilean plantations and in a Spanish site. The correlation between SPEI and tree-ring width indices showed different patterns between and within countries. Overall, exotic plantations showed lower sensitivity to climate variability than native stands. Therefore, stone pine plantations may be useful to assist in mitigating climate change. Full article

Radial tree growth at high-elevation and high-latitude sites is predominantly controlled by changes in summer temperature. This relationship is, however, expected to weaken under projected global warming, which questions the reliability of tree-ring chronologies for climate reconstructions. Here, we examined the growth–climate response patterns of five tree-ring width (TRW) and maximum latewood density (MXD) chronologies of larch (Larix sibirica) from upper-treeline ecotones in the Altai Mountains, which is a key region for developing millennial-long dendroclimatic records in inner Eurasia. The TRW and MXD chronologies exhibited significant year-to-year coherency within and between the two parameters (p < 0.001). While TRW is mostly influenced by temperature changes during the first half of the growing season from June to July (r = 0.66), MXD is most strongly correlated with May–August temperatures (r = 0.73). All seasonal temperature signals are statistically significant at the 99% confidence level, temporally stable back to 1940 CE, the period with reliable instrumental measurements, and spatially representative for a vast area of inner Eurasia between northeastern Kazakhstan in the west, northern Mongolia in the east, southern Russia in the north and northwestern China in the south. Our findings demonstrate the paleoclimatic potential of TRW and especially MXD chronologies and reject any sign of the ´divergence problem´ at these high-elevation, mid-latitude larch sites. Full article