Global warming and frequent extreme drought events lead to tree death and extensive forest decline,but the underlying mechanism is not clear.In drought years,cambial development is more sensitive to climate change,but...Global warming and frequent extreme drought events lead to tree death and extensive forest decline,but the underlying mechanism is not clear.In drought years,cambial development is more sensitive to climate change,but in different phenological stages,the response rela-tionship is nonlinear.Therefore,the dynamic relationship between tree radial growth and climatic/environmental fac-tors needs to be studied.We thus continuously monitored radial growth of Qinghai spruce(Picea crassifolia Kom.)and environmental factors from January 2021 to November 2022 using point dendrometers and portable meteorological weather stations in the central area of the Qilian Mountains.The relationship and stability between the radial growth of Qinghai spruce and environmental factors were compared for different levels of drought in 2021 and 2022.The year 2022 had higher temperatures and less precipitation and was drier than 2021.Compared with 2021,the growing period in 2022 for Qinghai spruce was 10 days shorter,maximum growth rate(Grmax)was 4.5μm·d^(-1) slower,and the initiation of growth was 6 days later.Growth of Qinghai spruce was always restricted by drought,and the stem radial increment(SRI)was more sensitive to precipitation and air relative humidity.Seasonal changes in cumulative radial growth were divided into four phenological stages according to the time of growth onset,cessation,and maximum growth rate(Grmax)of Qinghai spruce.Stability responses of SRI to climate change were stronger in Stage 3 and Stage 4 of 2021 and stronger in Stage 1(initiation growth stage)and Stage 3 of 2022.The results provide important information on the growth of the trees in response to drought and for specific managing forests as the climate warms.展开更多
Multi-functional dendrometer is a kind of forestry tool that can measure multiple factors of forest.By combining sensor technology and computer technology,a digital multi-function dendrometer has been developed,which ...Multi-functional dendrometer is a kind of forestry tool that can measure multiple factors of forest.By combining sensor technology and computer technology,a digital multi-function dendrometer has been developed,which integrated the functions of measuring height,distance,azimuth, slope,elevation,form quotient of any parts of the stem into one body at the same test.The dendrometer can fit the complex forest environment,solve the difficult problems in aspects of plant height,measure distance,central diameter and form quotient of breast height.The accuracy can meet the requirements of general forest survey.展开更多
Growth of commercial forestry is highly dependent on the availability of fast-growing planting materials. Consequently, the efficient utilization of fastgrowing plantations can greatly impact productivity. The objecti...Growth of commercial forestry is highly dependent on the availability of fast-growing planting materials. Consequently, the efficient utilization of fastgrowing plantations can greatly impact productivity. The objectives of this study were to evaluate variations in the growth potential of two clones and to estimate the average stem radial growth advantage of a fast-growing clone using data obtained from Sappi landholdings in eastern South Africa and a mixed modelling approach that permits the incorporation of covariance structure into the statistical model. During the first 2 years of growth, the stem radius of nine trees each of two clones was measured using dendrometer attached to the tree. A second-degree fractional polynomial model was chosen to show the functional relationship between stem radius and tree age. Growth of the two hybrid clones differed significantly. The Eucalyptus grandis×Eucalyptus urophylla clone grew faster than the E. grandis×camaldulensis clone, indicating better genetic potential for rapid growth and yield. This study can be considered as starting point to further compare the potential for rapid growth of several hybrid clones using the longitudinal data modelling approach.展开更多
The effect of tree age and climatic variables on stem radial growth of two hybrid clones of Eucalyptus was determined using longitudinal data from eastern South Africa.The stem radius of was measured weekly as the res...The effect of tree age and climatic variables on stem radial growth of two hybrid clones of Eucalyptus was determined using longitudinal data from eastern South Africa.The stem radius of was measured weekly as the response variable.In addition to tree age,average weekly temperature,solar radiation,relative humidity and wind speed were simultaneously recorded with total rainfall at the site.An additive mixed effects model that incorporates a non-parametric smooth function was used.The results of the analysis indicate that the relationship between stem radius and each of the covariates can be explained by nonlinear functions.Models that account for the effect of clone and season together with their interaction in the parametric part of the additive mixed model were also fitted.The interaction between clone and season was not significant in all cases.For analyzing the joint effect all the covariates,additive mixed models that included two or more covariates were fitted.A significant effect of tree age was found in all cases.Although tree age was the key determinant of stem radial growth,weather variables also had a significant effect that was dependent on season.展开更多
The explicit purpose of this study was to characterize climate and vegetation along the western slope of the El Sira Mountains(Peru)and evaluate radial tree growth in response to seasonal rainfall anomalies.From May 2...The explicit purpose of this study was to characterize climate and vegetation along the western slope of the El Sira Mountains(Peru)and evaluate radial tree growth in response to seasonal rainfall anomalies.From May 2011 until September 2015,we monitored radial stem growth of 67 trees using point dendrometers and measured climate within five sites along an altitudinal gradient.The transect extends from lowland terra firme forests,over submontane forests,late and mid successional montane cloud forests up to exposed elfin forests.Monthly rainfall estimates by the TRMM PR satellite(product 3B42)were highly correlated with our rain gauge observations but underestimate rainfall at high altitudes.Different intra-annual tree growth patterns could be identified within each elevational forest type,showing species with strictly seasonal growth,continuous growth or alternating growth patterns independent of the seasons.Stem growth at each site was generally larger during rainy seasons,except for the elfin forest.The rainy season from October 2013 to March 2014 was extraordinarily dry,with only 73%of long-term mean precipitation received,which resulted in reduced radial growth,again with the exception of the elfin forest.This indicates that montane tropical rain forests may suffer from prolonged droughts,while exposed ridges with elfin forests still receive plenty of precipitation and benefit from receiving more solar radiation for photosynthesis.展开更多
Growth response of conifers is species-specific and depends on site and climate conditions.Studies on daily radial stem growth use different analytical approaches to determine species reactions to environmental condit...Growth response of conifers is species-specific and depends on site and climate conditions.Studies on daily radial stem growth use different analytical approaches to determine species reactions to environmental conditions.These results contribute to improve forecasts of tree growth under a changing climate.During 2013 and2014,radial stem growth of 33 mature Cedrus libani individuals growing under different climatic conditions in Turkey and Germany was monitored hourly using high precision point dendrometers.Stem radius increments(SRI)were extracted from dendrometer readings.The annual course of SRI showed site-specific patterns with mean daily values ranging between 9.9 and 29.3μm over the growing season.Correlation and principal component analyses indicated that humidity and low temperatures during the growing season favored SRI.Multiple regression analyses demonstrated that precipitation and relative air humidity were the most important factors influencing daily SRI.Climate-growth relationships were further evaluated using the regression tree method.Precipitation was the most significant factor on daily SRI for all sites.The close coupling of SRI to relative air humidity and precipitation underlines the importance of stem water status for radial stem growth of C.libani which is native to regions with summer drought.It further explains the superior growth of C.libani in Germany.展开更多
Background: Stem radial growth in forests is not uniform. Rather, it is characterized by periods of relatively fast or slow growth, or sometimes no growth at all. These fluctuations are generally a function of varying...Background: Stem radial growth in forests is not uniform. Rather, it is characterized by periods of relatively fast or slow growth, or sometimes no growth at all. These fluctuations are generally a function of varying environmental conditions(e.g. water availability) and, importantly, will also be associated with adjustments in proprties in the wood formed. Stand level conditions and forest management, particularly thinning and stand density will, thowever, also have a major influence on patterns of growth variation. We explore how different thinning histories and/or stand densities influence these dynamics of tree growth in the important commercial plantation species Pinus radiata D. Don.Methods: Daily stem size change was measured using electronic point dendrometers over two growing seasons on P. radiata trees at two sites, subjected to different thinning regimes. Timing, rates and periodicity of annual growth were calculated from these data.Results: Greater overall cross-sectional growth in thinned plots was driven mainly by two dynamics. First, the cessation of seasonal growth occurred at least 3 weeks later in the stands in which thinning had taken place. There was no difference between thinned/unthinned stands, however, in the timing of growth onset. Second, within the longer season, trees in thinned plots had more growth days(as much as 20% more) than unthinned plots. The rates of growth on days when growth occurred were not different, however. In this context, it is notable that in trees in the unthinned plots experiencing the most severe competition there were strong "pulses" of growth following drought-breaking rainfall events. Unthinned plots at high stand densities also maintained a smaller(but consistent) zone of dividing cells throughout the season than thinned plots.Conclusions: In Pinus radiata growing under conditions as in our study, conditions late in summer, particularly drought, have an important effect on the timing of cessation of growth. Early season temperature appears to have no effect in determining timing of annual growth. Limiting conditions during the season reduce growing duration, and thus total growth, more in unthinned stands than thinned stands. These findings are valuable in developing new generations of fine-scale growth and wood property models.展开更多
Traditional dendroclimatology research is based on the statistical correlation between tree-ring chronology and modem observation data, but lacks consideration of the mechanisms of tree-ring growth. In order to recons...Traditional dendroclimatology research is based on the statistical correlation between tree-ring chronology and modem observation data, but lacks consideration of the mechanisms of tree-ring growth. In order to reconstruct past climatic conditions more reliably, the response of stem radius growth dynamics should be studied in detail. At present, in intemational researches, monitoring and simulation methods are generally treated as two separate approaches. The monitoring method generally consists of dendrometer measurements, micro-coring, and pinning. Here, we present the research progress of stem radius growth dynamics studies derived from these methods, and provide prospects for future study.展开更多
Information on changes in diameter at breast height (DBH) is important for net primary production (NPP) estimates, timing of forest inventory, and forest management. In the present study, patterns of DBH change we...Information on changes in diameter at breast height (DBH) is important for net primary production (NPP) estimates, timing of forest inventory, and forest management. In the present study, patterns of DBH change were measured under field conditions during the dry season for three dominant and native tree species in a monsoon evergreen broad-leaved forest in the Dinghushan Biosphere Reserve. For each tree species, different patterns of DBH change were observed. In the case of the fast-growing tree species Castanopsis chinensis Hance, large diurnal fluctuations occur, with a peak DBH in the early morning (around 05:00 h) that decreases to a minimum by about 14:00 h. Both Schima superba Gardn. et Chemp and Cryptocarya chinensis (Hance) Hemsh exhibited less diurnal swelling and shrinkage. Diurnal fluctuations for these species were observed on a few occasions over the period of observation. Graphical comparisons and statistical analysis of changes in DBH with meteorological variables indicate that for different trees, the different changes in DBH observed responded to different meteorological variables. Large stem changes were found to occur for Ca. chinensis trees that were associated with variations in solar radiation. However, both S. superba and Cr. chinensis were found to be less sensitive to solar radiation. Changes in the DBH of these two species were found to be controlled mainly by soil temperature and soil moisture. During the later dry season, with a lower soil temperature and soil moisture, all three tree species stopped growing and only negligible shrinkage, expansion, or fluctuation occurred, suggesting that the optimum time to measure tree growth in the Dinghushan Biosphere Reserve is the later dry season.展开更多
基金supported by Natural Science Foundation of Gansu (No.21JR7RA111)CAS Light of West China Program (2020XBZG-XBQNXZ-A)the 2022 Major scientific Research Project Cultivation Plan of Northwest Normal University (WNU-LKZD2022-04).
文摘Global warming and frequent extreme drought events lead to tree death and extensive forest decline,but the underlying mechanism is not clear.In drought years,cambial development is more sensitive to climate change,but in different phenological stages,the response rela-tionship is nonlinear.Therefore,the dynamic relationship between tree radial growth and climatic/environmental fac-tors needs to be studied.We thus continuously monitored radial growth of Qinghai spruce(Picea crassifolia Kom.)and environmental factors from January 2021 to November 2022 using point dendrometers and portable meteorological weather stations in the central area of the Qilian Mountains.The relationship and stability between the radial growth of Qinghai spruce and environmental factors were compared for different levels of drought in 2021 and 2022.The year 2022 had higher temperatures and less precipitation and was drier than 2021.Compared with 2021,the growing period in 2022 for Qinghai spruce was 10 days shorter,maximum growth rate(Grmax)was 4.5μm·d^(-1) slower,and the initiation of growth was 6 days later.Growth of Qinghai spruce was always restricted by drought,and the stem radial increment(SRI)was more sensitive to precipitation and air relative humidity.Seasonal changes in cumulative radial growth were divided into four phenological stages according to the time of growth onset,cessation,and maximum growth rate(Grmax)of Qinghai spruce.Stability responses of SRI to climate change were stronger in Stage 3 and Stage 4 of 2021 and stronger in Stage 1(initiation growth stage)and Stage 3 of 2022.The results provide important information on the growth of the trees in response to drought and for specific managing forests as the climate warms.
文摘Multi-functional dendrometer is a kind of forestry tool that can measure multiple factors of forest.By combining sensor technology and computer technology,a digital multi-function dendrometer has been developed,which integrated the functions of measuring height,distance,azimuth, slope,elevation,form quotient of any parts of the stem into one body at the same test.The dendrometer can fit the complex forest environment,solve the difficult problems in aspects of plant height,measure distance,central diameter and form quotient of breast height.The accuracy can meet the requirements of general forest survey.
文摘Growth of commercial forestry is highly dependent on the availability of fast-growing planting materials. Consequently, the efficient utilization of fastgrowing plantations can greatly impact productivity. The objectives of this study were to evaluate variations in the growth potential of two clones and to estimate the average stem radial growth advantage of a fast-growing clone using data obtained from Sappi landholdings in eastern South Africa and a mixed modelling approach that permits the incorporation of covariance structure into the statistical model. During the first 2 years of growth, the stem radius of nine trees each of two clones was measured using dendrometer attached to the tree. A second-degree fractional polynomial model was chosen to show the functional relationship between stem radius and tree age. Growth of the two hybrid clones differed significantly. The Eucalyptus grandis×Eucalyptus urophylla clone grew faster than the E. grandis×camaldulensis clone, indicating better genetic potential for rapid growth and yield. This study can be considered as starting point to further compare the potential for rapid growth of several hybrid clones using the longitudinal data modelling approach.
文摘The effect of tree age and climatic variables on stem radial growth of two hybrid clones of Eucalyptus was determined using longitudinal data from eastern South Africa.The stem radius of was measured weekly as the response variable.In addition to tree age,average weekly temperature,solar radiation,relative humidity and wind speed were simultaneously recorded with total rainfall at the site.An additive mixed effects model that incorporates a non-parametric smooth function was used.The results of the analysis indicate that the relationship between stem radius and each of the covariates can be explained by nonlinear functions.Models that account for the effect of clone and season together with their interaction in the parametric part of the additive mixed model were also fitted.The interaction between clone and season was not significant in all cases.For analyzing the joint effect all the covariates,additive mixed models that included two or more covariates were fitted.A significant effect of tree age was found in all cases.Although tree age was the key determinant of stem radial growth,weather variables also had a significant effect that was dependent on season.
基金supported by the German Federal Ministry of the EnvironmentNature Conservation and Nuclear Safety(BMU)the German Corporation for International Cooperation GmbH(GIZ)。
文摘The explicit purpose of this study was to characterize climate and vegetation along the western slope of the El Sira Mountains(Peru)and evaluate radial tree growth in response to seasonal rainfall anomalies.From May 2011 until September 2015,we monitored radial stem growth of 67 trees using point dendrometers and measured climate within five sites along an altitudinal gradient.The transect extends from lowland terra firme forests,over submontane forests,late and mid successional montane cloud forests up to exposed elfin forests.Monthly rainfall estimates by the TRMM PR satellite(product 3B42)were highly correlated with our rain gauge observations but underestimate rainfall at high altitudes.Different intra-annual tree growth patterns could be identified within each elevational forest type,showing species with strictly seasonal growth,continuous growth or alternating growth patterns independent of the seasons.Stem growth at each site was generally larger during rainy seasons,except for the elfin forest.The rainy season from October 2013 to March 2014 was extraordinarily dry,with only 73%of long-term mean precipitation received,which resulted in reduced radial growth,again with the exception of the elfin forest.This indicates that montane tropical rain forests may suffer from prolonged droughts,while exposed ridges with elfin forests still receive plenty of precipitation and benefit from receiving more solar radiation for photosynthesis.
基金Field studies were carried out within the project funded by the German Federal Ministry of Education and Research(01DL12041)in cooperation with the Southwest Anatolian Forest Research Institute(SAFRI)in Antalya and the Ecological Botanical Gardens(EBG)in Bayreuth.
文摘Growth response of conifers is species-specific and depends on site and climate conditions.Studies on daily radial stem growth use different analytical approaches to determine species reactions to environmental conditions.These results contribute to improve forecasts of tree growth under a changing climate.During 2013 and2014,radial stem growth of 33 mature Cedrus libani individuals growing under different climatic conditions in Turkey and Germany was monitored hourly using high precision point dendrometers.Stem radius increments(SRI)were extracted from dendrometer readings.The annual course of SRI showed site-specific patterns with mean daily values ranging between 9.9 and 29.3μm over the growing season.Correlation and principal component analyses indicated that humidity and low temperatures during the growing season favored SRI.Multiple regression analyses demonstrated that precipitation and relative air humidity were the most important factors influencing daily SRI.Climate-growth relationships were further evaluated using the regression tree method.Precipitation was the most significant factor on daily SRI for all sites.The close coupling of SRI to relative air humidity and precipitation underlines the importance of stem water status for radial stem growth of C.libani which is native to regions with summer drought.It further explains the superior growth of C.libani in Germany.
基金funded in large part by a grant(PNC 196-1011)from Forest and Wood Products Australia(FWPA)and funding and in-kind support from HVP,FSA and CSIRO
文摘Background: Stem radial growth in forests is not uniform. Rather, it is characterized by periods of relatively fast or slow growth, or sometimes no growth at all. These fluctuations are generally a function of varying environmental conditions(e.g. water availability) and, importantly, will also be associated with adjustments in proprties in the wood formed. Stand level conditions and forest management, particularly thinning and stand density will, thowever, also have a major influence on patterns of growth variation. We explore how different thinning histories and/or stand densities influence these dynamics of tree growth in the important commercial plantation species Pinus radiata D. Don.Methods: Daily stem size change was measured using electronic point dendrometers over two growing seasons on P. radiata trees at two sites, subjected to different thinning regimes. Timing, rates and periodicity of annual growth were calculated from these data.Results: Greater overall cross-sectional growth in thinned plots was driven mainly by two dynamics. First, the cessation of seasonal growth occurred at least 3 weeks later in the stands in which thinning had taken place. There was no difference between thinned/unthinned stands, however, in the timing of growth onset. Second, within the longer season, trees in thinned plots had more growth days(as much as 20% more) than unthinned plots. The rates of growth on days when growth occurred were not different, however. In this context, it is notable that in trees in the unthinned plots experiencing the most severe competition there were strong "pulses" of growth following drought-breaking rainfall events. Unthinned plots at high stand densities also maintained a smaller(but consistent) zone of dividing cells throughout the season than thinned plots.Conclusions: In Pinus radiata growing under conditions as in our study, conditions late in summer, particularly drought, have an important effect on the timing of cessation of growth. Early season temperature appears to have no effect in determining timing of annual growth. Limiting conditions during the season reduce growing duration, and thus total growth, more in unthinned stands than thinned stands. These findings are valuable in developing new generations of fine-scale growth and wood property models.
基金funded by the CAS Strategic Priority Research Program (Grant No. XDA05080801)the National Science Foundation of China (Grant No. 41071130)the National Basic Research Program of China (973 Program) (No. 2010CB950104)
文摘Traditional dendroclimatology research is based on the statistical correlation between tree-ring chronology and modem observation data, but lacks consideration of the mechanisms of tree-ring growth. In order to reconstruct past climatic conditions more reliably, the response of stem radius growth dynamics should be studied in detail. At present, in intemational researches, monitoring and simulation methods are generally treated as two separate approaches. The monitoring method generally consists of dendrometer measurements, micro-coring, and pinning. Here, we present the research progress of stem radius growth dynamics studies derived from these methods, and provide prospects for future study.
基金Supported by the International Foundation for Science(D/3491-1)the Knowledge Innovation Program of the Chinese Academy of Sciences (KSCX2-SW-120)
文摘Information on changes in diameter at breast height (DBH) is important for net primary production (NPP) estimates, timing of forest inventory, and forest management. In the present study, patterns of DBH change were measured under field conditions during the dry season for three dominant and native tree species in a monsoon evergreen broad-leaved forest in the Dinghushan Biosphere Reserve. For each tree species, different patterns of DBH change were observed. In the case of the fast-growing tree species Castanopsis chinensis Hance, large diurnal fluctuations occur, with a peak DBH in the early morning (around 05:00 h) that decreases to a minimum by about 14:00 h. Both Schima superba Gardn. et Chemp and Cryptocarya chinensis (Hance) Hemsh exhibited less diurnal swelling and shrinkage. Diurnal fluctuations for these species were observed on a few occasions over the period of observation. Graphical comparisons and statistical analysis of changes in DBH with meteorological variables indicate that for different trees, the different changes in DBH observed responded to different meteorological variables. Large stem changes were found to occur for Ca. chinensis trees that were associated with variations in solar radiation. However, both S. superba and Cr. chinensis were found to be less sensitive to solar radiation. Changes in the DBH of these two species were found to be controlled mainly by soil temperature and soil moisture. During the later dry season, with a lower soil temperature and soil moisture, all three tree species stopped growing and only negligible shrinkage, expansion, or fluctuation occurred, suggesting that the optimum time to measure tree growth in the Dinghushan Biosphere Reserve is the later dry season.