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Norway spruce (Picea abies) forests in temperate zones are already reacting to short-term extreme summer heatwaves, threatening the vitality of trees and forest productivity, and can even lead to local and regional dieback events. Examining quantitative wood anatomy can provide helpful information in terms of understanding the physiology mechanisms and related responses of conifer trees to local environmental interactions in relation to tracheid adaptive capacity. This study analysed the tracheid functional anatomical traits (FATs) plasticity of six young Norway spruce trees growing in two mesic research plots with high annual precipitation (~43%) and air temperature differences during 2010–2017. The research plots are located in the sub-mountainous (Rájec Němčice) and mountainous (Bílý Kříž) belts of the Moravia region, Czech Republic. Vapour pressure deficit and cell wall reinforcement index (CWRI) were shown to be the most representative environmental parameters as proxies of dry conditions. Tracheid FATs indicated latewood phenological plasticity sensitivity, with more pronounced variability in the warmer and drier plots. Latewood tracheids of Norway spruce trees grown in the RAJ formed significantly thicker cell walls than BK during the studied period. The observed differences between the two research plots indicate additional support for tracheid cells' hydraulic safety against cavitation and potential traces of adaptive acclimatization response. [ABSTRACT FROM AUTHOR]

Investigating the spatiotemporal variations in the Normalized Difference Vegetation Index (NDVI) in the Shanxi section of the Yellow River Basin and its coal mining areas holds significant importance for dynamic vegetation monitoring and mining area management. This study employs MODIS NDVI data and combines various analytical methods, including trend analysis and coefficient of variation analysis, to reveal the characteristics of NDVI spatiotemporal variations and their response to climatic factors in the study area. The results indicate the following: (1) The overall NDVI in the Shanxi section of the Yellow River Basin exhibits a growth trend with an annual growth rate of 1.82% and a 36% increase. Among the mining areas, the NDVI increase is most prominent in the Hebaopian mining area with a 100% growth, while the QinYuan mining area shows the lowest increase at 21%; (2) The NDVI in the Shanxi section of the Yellow River Basin displays high fluctuations, with areas of moderate and high fluctuations accounting for 54.39% of the total. The Hebaopian mining area has a substantial portion of high-fluctuation areas at 38.85%; (3) According to the Hurst index analysis, future vegetation changes in the Shanxi section of the Yellow River Basin are uncertain, with approximately 9.77% of areas expected to continue improving; (4) The variations in the NDVI and climatic factors across the Shanxi section of the Yellow River Basin display spatial heterogeneity. The NDVI exhibits a positive correlation with both temperature and precipitation, with the correlation with precipitation being more pronounced than that with temperature. Precipitation exerts a more significant influence on the NDVI than temperature. These findings not only provide scientific guidance for vegetation restoration and area management in the Shanxi section of the Yellow River Basin and its mining areas but also serve as a scientific basis for decision making regarding vegetation management under the influence of climate change and human activities. [ABSTRACT FROM AUTHOR]

Improved understanding of the responses of stem radial growth to climates is necessary for modeling and predicting the response of forest ecosystems to future climate change. We used dendrochronological methods to study climate effects on the radial growth of a subalpine deciduous conifer, Larix potaninii. Tree-ring residual chronologies were developed for five sites at the upper distributional limits in the Central Hengduan Mountains, Southwestern China. Redundancy analysis and response function were used to compare inter-annual variability in growth sensitivity among the chronologies and to identity key climatic factors controlling tree radial growth. The results showed that both precipitation and temperature influenced tree growth, and response patterns were consistent for five chronologies. During the current year's early growing season (Tmean in May and Tmax in June), temperature positively affected the radial growth of L. potaninii, while September Tmin and October precipitation in the previous year and May and June precipitation in the current year all had negative impacts on its radial growth. L. potaninii growth appeared to be mainly limited by photothermal conditions in May and June. In the context of increasing CO2 concentrations accompanied with warmer temperatures, future climate change would likely stimulate the radial growth of L. potaninii in Central Hengduan Mountain. [ABSTRACT FROM AUTHOR]

Norway spruce (Picea abies) forests in temperate zones are already reacting to short-term extreme summer heatwaves, threatening the vitality of trees and forest productivity, and can even lead to local and regional dieback events. Examining quantitative wood anatomy can provide helpful information in terms of understanding the physiology mechanisms and related responses of conifer trees to local environmental interactions in relation to tracheid adaptive capacity. This study analysed the tracheid functional anatomical traits (FATs) plasticity of six young Norway spruce trees growing in two mesic research plots with high annual precipitation (~43%) and air temperature differences during 2010–2017. The research plots are located in the sub-mountainous (Rájec Němčice) and mountainous (Bílý Kříž) belts of the Moravia region, Czech Republic. Vapour pressure deficit and cell wall reinforcement index (CWRI) were shown to be the most representative environmental parameters as proxies of dry conditions. Tracheid FATs indicated latewood phenological plasticity sensitivity, with more pronounced variability in the warmer and drier plots. Latewood tracheids of Norway spruce trees grown in the RAJ formed significantly thicker cell walls than BK during the studied period. The observed differences between the two research plots indicate additional support for tracheid cells’ hydraulic safety against cavitation and potential traces of adaptive acclimatization response.

In woody plants, bark is an important protective tissue which can participate in photosynthesis, manage water loss, and transport assimilates. Studying the bark anatomical traits can provide insight into plant environmental adaptation strategies. However, a systematic understanding of the variability in bark anatomical traits and their drivers is lacking in woody plants. In this study, the bark anatomical traits of 23 Picea species were determined in a common garden experiment. We analyzed interspecific differences and interpreted the patterns in bark anatomical traits in relation to phylogenetic relationships and climatic factors of each species according to its global distribution. The results showed that there were interspecific differences in bark anatomical traits of Picea species. Phloem thickness was positively correlated with parenchyma cell size, possibly related to the roles of parenchyma cells in the radial transport of assimilates. Sieve cell size was negatively correlated with the radial diameter of resin ducts, and differences in sieve cells were possibly related to the formation and expansion of resin ducts. There were no significant phylogenetic signals for any bark anatomical trait, except the tangential diameter of resin ducts. Phloem thickness and parenchyma cell size were affected by temperature-related factors of their native range, while sieve cell size was influenced by precipitation-related factors. Bark anatomical traits were not significantly different under wet and dry climates. This study makes an important contribution to our understanding of variability in bark anatomical traits among Picea species and their ecological adaptations. [ABSTRACT FROM AUTHOR]

In the past few decades, the East Asian summer monsoon (EASM) has experienced an unprecedented weakening, exacerbating drought in northern China, especially in the monsoon margin area. Improving our understanding of monsoon variability will benefit agricultural production, ecological construction, and disaster management. Tree-ring is widely used as proxy data for extending the monsoon history. However, in the East Asian monsoon margin, the tree-ring width were mostly formed before the rainy season, thus may have limited ability to indicate the monsoon variability. Intra-annual density fluctuations (IADFs) can provide higher resolution information on tree growth as well as evidence of short-term climate events. Here, we used Chinese pine (Pinus tabuliformis Carr.) samples from the eastern edge of the Chinese Loess Plateau (CLP), where the climate is deeply affected by monsoon, to investigate the response of tree growth and IADFs frequency to climate variation. We show that tree-ring width and IADFs record significantly different climatic signals. The former was mainly affected by moisture conditions at the end of the previous growing season and the current spring. While the latter was common in years when severe droughts occurred in June and July, especially in June. This period coincides with the onset of the EASM, so we further analyzed the relationship between IADFs frequency and the rainy season. Both correlation analysis and the GAM model suggest that the frequent occurrence of IADFs may be related to the late start of the monsoon rainy season, meaning that we have found a new indicator in tree-ring records that can capture monsoon anomalies. Our results provide further insight into drought variation in the eastern CLP, which also implicates the Asian summer monsoon dynamic. [ABSTRACT FROM AUTHOR]

With the rapid development of wind power generation， the impact of the construction and operation of utility-scale wind farms on the local climate has attracted extensive attention.In order to study the characteristics of the local climatic response to the deployment of wind farms under different surface conditions， the area from Wulan Chaka to Gonghe Shazhu Yuxiang， which is located in the southwest of Qinghai Lake， was chosen as center， and the mesoscale meteorological numerical model WRF （Weather Research and Forecasting Model） and the Fitch wind turbine model were carried out under the conditions of flat canyons， high-altitude mountains and water body， respectively.The results showed that： Under the ideal situation of the same installed capacity， the averaged wind speed inside the wind farms showed the significant decrease trends under the three sensitivity experiments， and the amplitude and scope of wind speed attenuation was stronger during nighttime than that during the daytime， and the wind speed attenuation in the vertical direction can reached up to 600 m.The 2 m temperature inside the wind farms located in flat canyons or water body mainly decreased， which was possibly related to the negative temperature gradient and the water evaporation enhancement， and the temperature cooling was more significant during nighttime while no significant changes in 2 m temperature were detected over the mountain wind farm.Meanwhile， the changes of 2 m humidity inside the wind farms were not obvious， and the overall decreased trends were mainly weak during nighttime.Due to rotation of the wind turbine， the planetary boundary layer height increased significantly.The characteristics of the local climatic response to the deployment of wind farms under different surface conditions were different， which was mainly related to the different climatic features under different surface conditions， and was also affected by the spatial layout of wind turbines.These results can provide some support for the design of climate-friendly wind farms.

The pattern of annual radial growth is influenced by various factors: the local growth conditions, the age structure, and the ecotypes or provenances of trees. A more in-depth approach to the study of specific growth patterns of tree forms is needed to predict the further genesis of forests. This research was carried out on healthy English oak trees of early (EF) and late (LF) phenological forms in Shipov Forest, Voronezh Region. The dendroclimatic analysis was performed on permanent sample plots in wet, dry, and very dry oak stands grown on different soil types. The effect of precipitation on annual ring width was assessed using a one-way ANOVA. The LF showed higher radial growth rates on wet sites than the EF did on dry ones. Their annual radial growth was less stable and more variable compared with the LF. For both phenoforms, the most important radial growth factors are the composite indicators reflecting the ratio of temperature and moisture (Selyaninov's hydrothermal coefficient and Lang's rain factor). Generally, the radial growth minima coincided in time on dry and wet sites, and the periods of maximum growth were associated with high-water years. [ABSTRACT FROM AUTHOR]

Investigating the spatiotemporal variations in the Normalized Difference Vegetation Index (NDVI) in the Shanxi section of the Yellow River Basin and its coal mining areas holds significant importance for dynamic vegetation monitoring and mining area management. This study employs MODIS NDVI data and combines various analytical methods, including trend analysis and coefficient of variation analysis, to reveal the characteristics of NDVI spatiotemporal variations and their response to climatic factors in the study area. The results indicate the following: (1) The overall NDVI in the Shanxi section of the Yellow River Basin exhibits a growth trend with an annual growth rate of 1.82% and a 36% increase. Among the mining areas, the NDVI increase is most prominent in the Hebaopian mining area with a 100% growth, while the QinYuan mining area shows the lowest increase at 21%; (2) The NDVI in the Shanxi section of the Yellow River Basin displays high fluctuations, with areas of moderate and high fluctuations accounting for 54.39% of the total. The Hebaopian mining area has a substantial portion of high-fluctuation areas at 38.85%; (3) According to the Hurst index analysis, future vegetation changes in the Shanxi section of the Yellow River Basin are uncertain, with approximately 9.77% of areas expected to continue improving; (4) The variations in the NDVI and climatic factors across the Shanxi section of the Yellow River Basin display spatial heterogeneity. The NDVI exhibits a positive correlation with both temperature and precipitation, with the correlation with precipitation being more pronounced than that with temperature. Precipitation exerts a more significant influence on the NDVI than temperature. These findings not only provide scientific guidance for vegetation restoration and area management in the Shanxi section of the Yellow River Basin and its mining areas but also serve as a scientific basis for decision making regarding vegetation management under the influence of climate change and human activities.

Improved understanding of the responses of stem radial growth to climates is necessary for modeling and predicting the response of forest ecosystems to future climate change. We used dendrochronological methods to study climate effects on the radial growth of a subalpine deciduous conifer, Larix potaninii. Tree-ring residual chronologies were developed for five sites at the upper distributional limits in the Central Hengduan Mountains, Southwestern China. Redundancy analysis and response function were used to compare inter-annual variability in growth sensitivity among the chronologies and to identity key climatic factors controlling tree radial growth. The results showed that both precipitation and temperature influenced tree growth, and response patterns were consistent for five chronologies. During the current year’s early growing season (Tmean in May and Tmax in June), temperature positively affected the radial growth of L. potaninii, while September Tmin and October precipitation in the previous year and May and June precipitation in the current year all had negative impacts on its radial growth. L. potaninii growth appeared to be mainly limited by photothermal conditions in May and June. In the context of increasing CO2 concentrations accompanied with warmer temperatures, future climate change would likely stimulate the radial growth of L. potaninii in Central Hengduan Mountain.

Recent years have seen a significant increase in natural disasters and vicissitudes of the environment, making it imperative to investigate their spatio-temporal dynamics. Using records extracted from historical documents and focusing on a typical hazardous area—Cangzhou, this study reconstructed databases of locust plagues and related disasters from 618 to 1949 to analyze the spatio-temporal evolution of the locust plagues as well as the locust breeding areas under the influence of patterns of water environment, and to clarify the climatic system and the social response to the locust plagues. The results suggested that: 1) Locust plagues occurred chiefly from March to June, while frequency and grades of the locust plagues rose in volatility, with mainly slight or moderate locust plagues becoming severe or catastrophic, the impact of the locust plagues increasing significantly from the Ming Dynasty to the Republic of China and the 17th century was the peak. 2) Locust plagues were widespread throughout Cangzhou, frequently occurring in densely hydrographic networks with significant hydrophilia. The locust breeding areas were divided into four main types: the eastern sea coast locust breeding areas, the central river flood locust breeding areas, the northwestern lake shore locust breeding areas, and the southwestern internal plain flood locust breeding areas. 3) There was no significant correlation between the locust plagues and temperature, while precipitation was closely related to the locust plagues. Locust plagues were misaligned with river floods and synchronized with droughts. 4) Locust plagues were formed by combination of climatic and social influences and act as mediums for transmitting negative impacts to social systems, resulting in social impacts and responses.

Through field investigation, UPLC-MS/MS technology and MaxEnt model were performed to predict the suitable distribution area for red huajiao (Zanthoxylum bungeanum maxim.) in China from 2021 s to 2060 s, and evaluate the effects of climate factors on the quality of red huajiao. The results demonstrated that mean temperature of the coldest quarter and min temperature of the coldest month were the most important environmental variables influencing red huajiao distribution. Suitable habitats for red huajiao were located mainly in dry and hot valley zone in the Qinba Mountains and the semi-humid and semi-arid areas of the Loess Plateau. The amides contents were higher in high suitability areas, while it was decreased in medium and low suitability areas, and temperature, wind speed and precipitation played a key role in their accumulation. This investigation was of great significance for the planting area optimization, quality control, benefit improvement and industrial development of red huajiao.

This paper intends to clarify that the spatial and temporal evolutionary patterns of regional vegetation and their relationship with climate form a premise of ecological conservation and environmental governance, and play an important role in maintaining regional ecosystem balance and promoting sustainable development. Based on measured data collected from NDVI remote sensing products and meteorological stations, NDVI variation in Anhui Province from 2001 to 2019 was determined through trend analysis and measurement methods involving coefficient of variation and Hurst index; in addition, the response to climatic factors was also explored. It was concluded that, firstly, in terms of spatiotemporal analysis, the interannual variation of NDVI in Anhui Province showed an increasing trend with a rate of 0.024/10 a, while the monthly variation showed a weak bimodal pattern, with the highest value in August and the lowest value in January. Furthermore, NDVI in Anhui Province showed significant spatial heterogeneity, with high values concentrated in mountainous regions in southern Anhui and Dabie Mountain region, and low values concentrated in the hilly areas of Jianghuai and areas along the Yangtze River. At the same time, the overall spatial variation of NDVI showed an increasing trend, and the areas with extremely significant and significant improvement in vegetation coverage accounted for 54.69% of the total area of Anhui Province. Secondly, in terms of the analysis on variation characteristics, the variation of NDVI in Anhui Province was generally stable, with an average CV coefficient of variation of 0.089, which, however, was quite different in different regions; meanwhile, the future trend of NDVI variation in the study areas was mostly in a random manner. Thirdly, the response of NDVI in Anhui Province to climatic factors showed significant spatial heterogeneity. NDVI was found to be positively correlated with precipitation and negatively correlated with temperature; in general, the impact of precipitation on NDVI was greater than that of temperature. In the 19 years studied, NDVI in Anhui Province showed an increasing trend; and climate, topography and human activities led to heterogeneous spatial distribution of vegetation. Therefore, in the future, the evolutionary trend of vegetation will be relatively random, and NDVI will be more greatly affected by temperature, than by precipitation. [ABSTRACT FROM AUTHOR]

The Qinling Mountains are located on the dividing line between the north and the south of China. Mt. Taibai, the study site, is the highest peak in the Qinling Mountains and also the highest peak in eastern mainland China. At Mt. Taibai, several dendroecological studies have been conducted on the relationship between tree-ring indices and climatic factors using traditional statistical methods. In this study, the response of Larix chinensis Beissn radial growth to climatic factors was explored in the treeline area of Mt. Taibai using the process-based Vaganov–Shashkin-Lite (VSL) model for the first time. The conclusions were obtained according to the analysis of the L. chinensis tree-ring samples collected from both the northern and southern slopes of Mt. Taibai. The VSL model showed that temperature limits L. chinensis growth during the entire growing season, while the model did not indicate precipitation as a limiting factor. The model showed significant positive correlations between the simulated and observed tree-ring chronologies for 1959–2013, excluding the uppermost sample site on the northern slope. However, the model performance deteriorated with increasing altitude, which may be due to the decreased sensitivity of radial growth to climatic factors above the treeline. [ABSTRACT FROM AUTHOR]

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Wildfires are one of the most important environmental factors controlling forest ecosystem physiology and the carbon balance in the permafrost zone of North Siberia. We investigated tree-ring width (TRW) and stable isotope chronologies in tree-ring cellulose (δ13CCell, δ18OCell) of Larix Gmelinii (Rupr.) Rupr. from a wet (WS) and a dry (DS) site. These sites are characterized by different fire histories (fire in 1852 at the wet and 1896 at the dry sites, respectively). TRW and δ18OCell are identified to be the most sensitive parameters in the changing tree growth conditions after fire. The differences in the soil seasonal thermal regime of sites after fires are shown in the relationship between the studied parameters. The δ13CCell values in tree rings from the two sites are positively correlated independently of the fire impact. This fact indicates that δ13CCell chronologies might be more adequate for climatic reconstruction in the region due to the climate signal consistency. Relationships of δ18OCell values between the two sites are still significantly positive 60 years after the fire impact. Dendroclimatic analysis indicates significant changes in tree-ring growth and isotopic ratio responses to climate due to the increased demand of water for trees during the post-fire period (deeper seasonal subsidence of permafrost). [ABSTRACT FROM AUTHOR]

Lakes are important indicators of climate change. The change in lake water level objectively reflects the availability of regional water resources. Analyzing the changes in water level and climate response of major lakes in countries along the “Belt and Road” is essential for sustainable water use and ecological protection. Based on the water level datasets of 39 large lakes (>400 km2) in China, Mongolia, and Russia (CMR) from 2002 to 2016, this study analyzed the spatiotemporal characteristics of water levels in major lakes of CMR, and their responses to climatic factors containing temperature, precipitation, and evapotranspiration. The results showed that (1) the water level of main lakes in CMR slightly increased with change rates ranged from −0.36 to 0.48 m/a, and the trends varied in lakes, (2) the water level of most lakes was sensitive to temperature with sensitivity value ranged from −2.14 m/°C to 5.59 m/°C, (3) changes of annual cumulative precipitation and evapotranspiration contributed most to the change of lake water level, but key factors affecting water level varied in lakes. Human activity is an important driving factor for the change in water levels and its impacts need further study.

The pattern of annual radial growth is influenced by various factors: the local growth conditions, the age structure, and the ecotypes or provenances of trees. A more in-depth approach to the study of specific growth patterns of tree forms is needed to predict the further genesis of forests. This research was carried out on healthy English oak trees of early (EF) and late (LF) phenological forms in Shipov Forest, Voronezh Region. The dendroclimatic analysis was performed on permanent sample plots in wet, dry, and very dry oak stands grown on different soil types. The effect of precipitation on annual ring width was assessed using a one-way ANOVA. The LF showed higher radial growth rates on wet sites than the EF did on dry ones. Their annual radial growth was less stable and more variable compared with the LF. For both phenoforms, the most important radial growth factors are the composite indicators reflecting the ratio of temperature and moisture (Selyaninov’s hydrothermal coefficient and Lang’s rain factor). Generally, the radial growth minima coincided in time on dry and wet sites, and the periods of maximum growth were associated with high-water years.

This paper intends to clarify that the spatial and temporal evolutionary patterns of regional vegetation and their relationship with climate form a premise of ecological conservation and environmental governance, and play an important role in maintaining regional ecosystem balance and promoting sustainable development. Based on measured data collected from NDVI remote sensing products and meteorological stations, NDVI variation in Anhui Province from 2001 to 2019 was determined through trend analysis and measurement methods involving coefficient of variation and Hurst index; in addition, the response to climatic factors was also explored. It was concluded that, firstly, in terms of spatiotemporal analysis, the interannual variation of NDVI in Anhui Province showed an increasing trend with a rate of 0.024/10 a, while the monthly variation showed a weak bimodal pattern, with the highest value in August and the lowest value in January. Furthermore, NDVI in Anhui Province showed significant spatial heterogeneity, with high values concentrated in mountainous regions in southern Anhui and Dabie Mountain region, and low values concentrated in the hilly areas of Jianghuai and areas along the Yangtze River. At the same time, the overall spatial variation of NDVI showed an increasing trend, and the areas with extremely significant and significant improvement in vegetation coverage accounted for 54.69% of the total area of Anhui Province. Secondly, in terms of the analysis on variation characteristics, the variation of NDVI in Anhui Province was generally stable, with an average CV coefficient of variation of 0.089, which, however, was quite different in different regions; meanwhile, the future trend of NDVI variation in the study areas was mostly in a random manner. Thirdly, the response of NDVI in Anhui Province to climatic factors showed significant spatial heterogeneity. NDVI was found to be positively correlated with precipitation and negatively correlated with temperature; in general, the impact of precipitation on NDVI was greater than that of temperature. In the 19 years studied, NDVI in Anhui Province showed an increasing trend; and climate, topography and human activities led to heterogeneous spatial distribution of vegetation. Therefore, in the future, the evolutionary trend of vegetation will be relatively random, and NDVI will be more greatly affected by temperature, than by precipitation.

The Qinling Mountains are located on the dividing line between the north and the south of China. Mt. Taibai, the study site, is the highest peak in the Qinling Mountains and also the highest peak in eastern mainland China. At Mt. Taibai, several dendroecological studies have been conducted on the relationship between tree-ring indices and climatic factors using traditional statistical methods. In this study, the response of Larix chinensis Beissn radial growth to climatic factors was explored in the treeline area of Mt. Taibai using the process-based Vaganov–Shashkin-Lite (VSL) model for the first time. The conclusions were obtained according to the analysis of the L. chinensis tree-ring samples collected from both the northern and southern slopes of Mt. Taibai. The VSL model showed that temperature limits L. chinensis growth during the entire growing season, while the model did not indicate precipitation as a limiting factor. The model showed significant positive correlations between the simulated and observed tree-ring chronologies for 1959–2013, excluding the uppermost sample site on the northern slope. However, the model performance deteriorated with increasing altitude, which may be due to the decreased sensitivity of radial growth to climatic factors above the treeline.

The application of quantitative wood anatomy (QWA) in dendroclimatic analysis offers deep insight into the climatic effect on tree-ring formation, which is crucial in understanding the forests’ response to climate change. However, interrelations between tree-ring traits should be accounted to separate climatic signals recorded during subsequent stages of cell differentiation. The study was conducted in the South Siberian alpine timberline on Pinus sibirica Du Tour, a species considered unpromising in dendroclimatology. Relationships between tree-ring width, cell number N, mean and maximum values of radial diameter D, and cell wall thickness (CWT) were quantified to obtain indexed anatomical chronologies. Exponential functions with saturation D(N) and CWT(N) were proposed, which explained 14–69% and 3–61% of their variability, respectively. Indexation unabated significance of the climatic signals but separated them within a season. Analysis of pointer years and climatic extremes revealed predominantly long-term climatogenic changes of P. sibirica radial growth and QWA and allowed to obtain QWA-based 11-year filtered reconstructions of vegetative season climatic characteristics (R2adj = 0.32–0.66). The revealed prevalence of low-frequency climatic reactions is probably explained by a strategy of slow accumulation and utilization of resources implemented by P. sibirica. It makes this species’ QWA a promising proxy for decadal climatic variations in various intra-seasonal timeframes.

Hydrological effects of forest thinning have been studied at small watershed scales using the paired watershed approach since the 1920s. However, how forest transpiration, a critical component of evapotranspiration, changes decades after thinning is not well understood despite its importance for modifying drought resilience of forest ecosystem under climate change. In a semi-arid mountainous area of northern China, we measured growing season sap flow of Pinus tabuliformis, a widely planted afforestation species, in 44-year-old monoculture plantation stands with low (983 stems ha-1), medium (1688 stems ha-1), and high (2160 stems ha-1) density. Three decades after thinning, diameters at breast height (DBH) were larger in sparse stands than in dense stands. While its relation with sapwood area was density independent, the accompanying high sapwood area at the tree level for sparse stands resulted the highest stand sapwood area in the medium density stand (33.26 m² ha-1), rather than in the high density stand (29.84 m² ha-1). Similar to short-term studies, sparse stands demonstrated higher sensitivity to climatic fluctuations and drought depressions than dense ones. Nevertheless, stand density had no effect on the isohydric strategy of Pinus tabuliformis. Contrary to the positive relation between stand density and stand canopy transpiration soon after thinning, sparse stands exhibited higher growing season canopy transpiration than dense stands three decades later. In the dry year 2014, these density differences were relatively most pronounced, with July-September transpiration totals of 56.7 mm, 31.1 mm, and 22.1 mm in the low, medium, and high density stands, respectively. Our findings highlighted that stand density was not an appropriate indicator of thinned forest transpiration over long time scales. Interactions between soil droughts and thinning on forest transpiration need to be further clarified, especially in longer periods of time. [ABSTRACT FROM AUTHOR]

Sierra Nevada snowpack is a critical water source for California’s growing population and agricultural industry. However, because mountain winters and springs are warming, on average, precipitation as snowfall relative to rain is decreasing, and snowmelt is earlier. The changes are stronger at mid-elevations than at higher elevations. The result is that the water supply provided by snowpack is diminishing. In this paper, we describe principal hydrologic responses to climatic and spatial geologic variations as gleaned from a series of observations including snowpack, stream-flow, and bedrock geology. Our analysis focused on peak (maximum) and base (minimum) daily discharge of the annual snowmelt-driven hydrographs from 18 Sierra Nevada watersheds and 24 stream gage locations using standard correlation methods. Insights into the importance of the relative magnitudes of peak flow and soil water storage led us to develop a hydrologic classification of mountain watersheds based on runoff versus base flow as a percentage of peak flow. Our findings suggest that watersheds with a stronger base flow response store more soil water than watersheds with a stronger peak-flow response. Further, the influence of antecedent wet or dry years is greater in watersheds with high base flow, measured as a percentage of peak flow. The strong correlation between 1) the magnitude of peak flow, and 2) snow water equivalent can be used to predict peak flow weeks in advance. A weaker but similar correlation can be used to predict the magnitude of base flow months in advance. Most of the watersheds show a trend that peak flow is occurring earlier in the year.

Assessing the characteristics and limiting factors of tree growth is of practical significance for environmental studies and climatic reconstruction, especially in climate transition zones. In this study, four sites of Pinus armandii Franeh are investigated to understand regional climate-tree growth response in Mt. Yao, central China. Based on the high similarity of four residual chronologies and high correlations between chronologies and climatic factors, we analyzed the correlations of regional residual chronology with monthly climatic factors and the self-calibrating Palmer Drought Severity Index (scPDSI) from 1961–2016. The results indicate that the hydrothermal combination of prior August and current May and the scPDSI in May are main limiting factors of regional tree growth in Mt. Yao. The results of stepwise regression models also show that temperature and scPDSI in May are the main limiting factors of tree growth, but the limiting effect of scPDSI is more than temperature in this month. Through the analysis of the number of tree growth years corresponding to high temperature and high scPDSI, it was further confirmed that scPDSI in May is the main limiting factor on the growth of P. armandii in Mt. Yao. However, the influence of scPDSI in May has weakened, while temperature in May has increasingly significant influence on tree growth. The above findings will help improve our understanding of forest dynamics in central China under global climate change.

Improved understanding of climate-growth relationships of multiple species is fundamental to understanding and predicting the response of forest growth to future climate change. Forests are mainly composed of conifers in Northwestern Yunnan Plateau, but variations of growth response to climate conditions among the species are not well understood. To detect the growth response of multiple species to climate change, we developed residual chronologies of four major conifers, i.e., George’s fir (Abies georgei Orr), Likiang spruce (Picea likiangensis (Franch.) E.Pritz.), Gaoshan pine (Pinus densata Mast.) and Chinese larch (Larix potaninii Batalin) at the upper distributional limits in Shika Snow Mountain. Using the dendroclimatology method, we analyzed correlations between the residual chronologies and climate variables. The results showed that conifer radial growth was influenced by both temperature and precipitation in Shika Snow Mountain. Previous November temperature, previous July temperature, and current May precipitation were the common climatic factors that had consistent influences on radial growth of the four species. Temperature in the previous post-growing season (September–October) and moisture conditions in the current growing season (June–August) were the common climatic factors that had divergent impacts on the radial growth of the four species. Based on the predictions of climate models and our understanding of the growth response of four species to climate variables, we may understand the growth response to climate change at the species level. It is difficult to predict future forest growth in the study area, since future climate change might cause both increases and decreases for the four species and indirect effects of climate change on forests should be considered. [ABSTRACT FROM AUTHOR]

In woody plants, bark is an important protective tissue which can participate in photosynthesis, manage water loss, and transport assimilates. Studying the bark anatomical traits can provide insight into plant environmental adaptation strategies. However, a systematic understanding of the variability in bark anatomical traits and their drivers is lacking in woody plants. In this study, the bark anatomical traits of 23 Picea species were determined in a common garden experiment. We analyzed interspecific differences and interpreted the patterns in bark anatomical traits in relation to phylogenetic relationships and climatic factors of each species according to its global distribution. The results showed that there were interspecific differences in bark anatomical traits of Picea species. Phloem thickness was positively correlated with parenchyma cell size, possibly related to the roles of parenchyma cells in the radial transport of assimilates. Sieve cell size was negatively correlated with the radial diameter of resin ducts, and differences in sieve cells were possibly related to the formation and expansion of resin ducts. There were no significant phylogenetic signals for any bark anatomical trait, except the tangential diameter of resin ducts. Phloem thickness and parenchyma cell size were affected by temperature-related factors of their native range, while sieve cell size was influenced by precipitation-related factors. Bark anatomical traits were not significantly different under wet and dry climates. This study makes an important contribution to our understanding of variability in bark anatomical traits among Picea species and their ecological adaptations., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Nie, Dong, Liu, Tan, Wang, Yuan, Ma, An, Liu, Xiao, Jiang, Jia and Wang.)

Through field investigation, UPLC-MS/MS technology and MaxEnt model were performed to predict the suitable distribution area for red huajiao ( Zanthoxylum bungeanum maxim.) in China from 2021 s to 2060 s, and evaluate the effects of climate factors on the quality of red huajiao. The results demonstrated that mean temperature of the coldest quarter and min temperature of the coldest month were the most important environmental variables influencing red huajiao distribution. Suitable habitats for red huajiao were located mainly in dry and hot valley zone in the Qinba Mountains and the semi-humid and semi-arid areas of the Loess Plateau. The amides contents were higher in high suitability areas, while it was decreased in medium and low suitability areas, and temperature, wind speed and precipitation played a key role in their accumulation. This investigation was of great significance for the planting area optimization, quality control, benefit improvement and industrial development of red huajiao., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Author(s).)

Sierra Nevada snowpack is a critical water source for California’s growing population and agricultural industry. However, because mountain winters and springs are warming, on average, precipitation as snowfall relative to rain is decreasing, and snowmelt is earlier. The changes are stronger at mid-elevations than at higher elevations. The result is that the water supply provided by snowpack is diminishing. In this paper, we describe principal hydrologic responses to climatic and spatial geologic variations as gleaned from a series of observations including snowpack, stream-flow, and bedrock geology. Our analysis focused on peak (maximum) and base (minimum) daily discharge of the annual snowmelt-driven hydrographs from 18 Sierra Nevada watersheds and 24 stream gage locations using standard correlation methods. Insights into the importance of the relative magnitudes of peak flow and soil water storage led us to develop a hydrologic classification of mountain watersheds based on runoff versus base flow as a percentage of peak flow. Our findings suggest that watersheds with a stronger base flow response store more soil water than watersheds with a stronger peak-flow response. Further, the influence of antecedent wet or dry years is greater in watersheds with high base flow, measured as a percentage of peak flow. The strong correlation between 1) the magnitude of peak flow, and 2) snow water equivalent can be used to predict peak flow weeks in advance. A weaker but similar correlation can be used to predict the magnitude of base flow months in advance. Most of the watersheds show a trend that peak flow is occurring earlier in the year.

Environmental and social factors are critical to determine the timing and duration of lekking behavior since they provide species with signs to maximize benefits over costs in sexual displays. However, these factors have rarely been studied under different environmental conditions, and thus, it remains unclear whether exogenous factors affecting group displays show a general species-specific pattern or whether they are population-specific. Using audio-trapping techniques, we compared factors influencing the daily occurrence and duration of lekking behavior in two populations of Hyla molleri and two populations of Hyla meridionalis located at the thermal extremes (coldest vs. hottest) of their Iberian distribution range. From 12,240 hourly recordings over one season, multimodel inference revealed that the major determinants of chorus occurrence were similar between populations and species (i.e., chorus size the previous day, daytime air temperature, relative humidity, and barometric pressure), and accounted for 51-79 % of its deviance. In contrast, the major determinants of chorus duration differed between populations and species (i.e., chorus size, number of day, and air temperature and relative humidity at the onset of the chorus), and accounted for 38-69 % of its variance. Our findings suggest that the decision making related to lek attendance is environment-dependent, takes place at time between lekking events, and is associated with exogenous factors that may be both stable across species ranges and population-specific when populations are under different climatic conditions. This intraspecific variation might be underlain by plasticity mechanisms providing tree frogs with means to cope with changing environments. Moreover, social facilitation related to male-male acoustic competition seems to play a relevant role on the daily time invested by males in lek attendance. [ABSTRACT FROM AUTHOR]

The application of quantitative wood anatomy (QWA) in dendroclimatic analysis offers deep insight into the climatic effect on tree-ring formation, which is crucial in understanding the forests' response to climate change. However, interrelations between tree-ring traits should be accounted to separate climatic signals recorded during subsequent stages of cell differentiation. The study was conducted in the South Siberian alpine timberline on Pinus sibirica Du Tour, a species considered unpromising in dendroclimatology. Relationships between tree-ring width, cell number N, mean and maximum values of radial diameter D, and cell wall thickness (CWT) were quantified to obtain indexed anatomical chronologies. Exponential functions with saturation D(N) and CWT(N) were proposed, which explained 14–69% and 3–61% of their variability, respectively. Indexation unabated significance of the climatic signals but separated them within a season. Analysis of pointer years and climatic extremes revealed predominantly long-term climatogenic changes of P. sibirica radial growth and QWA and allowed to obtain QWA-based 11-year filtered reconstructions of vegetative season climatic characteristics (R2adj = 0.32–0.66). The revealed prevalence of low-frequency climatic reactions is probably explained by a strategy of slow accumulation and utilization of resources implemented by P. sibirica. It makes this species' QWA a promising proxy for decadal climatic variations in various intra-seasonal timeframes. [ABSTRACT FROM AUTHOR]

Assessing the characteristics and limiting factors of tree growth is of practical significance for environmental studies and climatic reconstruction, especially in climate transition zones. In this study, four sites of Pinus armandii Franeh are investigated to understand regional climate-tree growth response in Mt. Yao, central China. Based on the high similarity of four residual chronologies and high correlations between chronologies and climatic factors, we analyzed the correlations of regional residual chronology with monthly climatic factors and the self-calibrating Palmer Drought Severity Index (scPDSI) from 1961–2016. The results indicate that the hydrothermal combination of prior August and current May and the scPDSI in May are main limiting factors of regional tree growth in Mt. Yao. The results of stepwise regression models also show that temperature and scPDSI in May are the main limiting factors of tree growth, but the limiting effect of scPDSI is more than temperature in this month. Through the analysis of the number of tree growth years corresponding to high temperature and high scPDSI, it was further confirmed that scPDSI in May is the main limiting factor on the growth of P. armandii in Mt. Yao. However, the influence of scPDSI in May has weakened, while temperature in May has increasingly significant influence on tree growth. The above findings will help improve our understanding of forest dynamics in central China under global climate change. [ABSTRACT FROM AUTHOR]