Pub Date : 2018-07-01DOI: 10.3959/1536-1098-74.2.135
M. R. Alexander, C. Rollinson, D. Moore, J. Speer, Darrin L. Rubino
Abstract Coarse woody debris (CWD; i.e. downed limbs and boles) serves numerous ecosystem functions, which vary according to the degree of decay. CWD decay is often described using five categories based on readily observed physical characteristics ranging from freshly fallen (Class I) to advanced decay with little structural integrity (Class V). Though useful in categorizing downed wood in a forest, these categories do not necessarily provide information about time since death or the decay process. Dendrochronology can be used to assign death dates to CWD and begin to provide a temporal description of the decay process. We used standard dendrochronological techniques to determine the death dates of 94 CWD samples from five common hardwood taxa in southern Indiana. Across taxa, the time since death of Class I (1.4 ± 1.7 years; mean ± SD; least decayed class) was significantly shorter than Class II (5.2 ± 3.6 years), which was shorter than the more decayed classes (Class III: 11.5 ± 4.9, and Class IV: 11.2 ± 5.6 years). Within this general trend, time since death within a decay class varied greatly among taxa. Combining dendrochronology techniques with visual decay characteristics can improve our understanding of CWD's role and provide a more precise timeline for biomass and nutrient turnover within forested systems.
{"title":"Determination of Death Dates of Coarse Woody Debris of Multiple Species in the Central Hardwood Region (Indiana, USA)","authors":"M. R. Alexander, C. Rollinson, D. Moore, J. Speer, Darrin L. Rubino","doi":"10.3959/1536-1098-74.2.135","DOIUrl":"https://doi.org/10.3959/1536-1098-74.2.135","url":null,"abstract":"Abstract Coarse woody debris (CWD; i.e. downed limbs and boles) serves numerous ecosystem functions, which vary according to the degree of decay. CWD decay is often described using five categories based on readily observed physical characteristics ranging from freshly fallen (Class I) to advanced decay with little structural integrity (Class V). Though useful in categorizing downed wood in a forest, these categories do not necessarily provide information about time since death or the decay process. Dendrochronology can be used to assign death dates to CWD and begin to provide a temporal description of the decay process. We used standard dendrochronological techniques to determine the death dates of 94 CWD samples from five common hardwood taxa in southern Indiana. Across taxa, the time since death of Class I (1.4 ± 1.7 years; mean ± SD; least decayed class) was significantly shorter than Class II (5.2 ± 3.6 years), which was shorter than the more decayed classes (Class III: 11.5 ± 4.9, and Class IV: 11.2 ± 5.6 years). Within this general trend, time since death within a decay class varied greatly among taxa. Combining dendrochronology techniques with visual decay characteristics can improve our understanding of CWD's role and provide a more precise timeline for biomass and nutrient turnover within forested systems.","PeriodicalId":54416,"journal":{"name":"Tree-Ring Research","volume":"74 1","pages":"135 - 143"},"PeriodicalIF":1.6,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3959/1536-1098-74.2.135","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44961836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.3959/1536-1098-74.2.144
M. Génova, A. Díez-Herrero, G. Furdada, M. Guinau, Ane Victoriano
Abstract The Portainé mountain catchment, containing the Port Ainé ski resort (Lleida, Spanish Pyrenees), displays active erosional and depositional phenomena caused by periodic torrential floods. These events present a potential risk and incur significant economic losses. In ungauged remote catchments (like Portainé), trees might be the only paleohydrological source of information regarding past floods. Thus, we estimated the temporal and spatial distribution of torrential floods by dendrogeomorphological techniques to assess whether human impact (land-use changes and infrastructure works) affected their frequency and magnitude. One-hundred and sixty-six samples from 67 trees belonging to 10 different species were analyzed; past flood events of the last 50 years were identified by dating and relating evidence between them. Moreover, a detailed geomorphological study was performed and the available historical data compiled. Our multi-evidence analysis provides new insight into the occurrence of paleofloods. Changes in flood frequency since 2006, especially from 2008, suggest that the geomorphological equilibrium has been disturbed, coinciding with both major earthworks within the ski resort and intense but not extraordinary rainfall. This conclusion has important implications for land planning and the design of future projects in the mountain watersheds.
{"title":"Dendrogeomorphological Evidence of Flood Frequency Changes and Human Activities (Portainé Basin, Spanish Pyrenees)","authors":"M. Génova, A. Díez-Herrero, G. Furdada, M. Guinau, Ane Victoriano","doi":"10.3959/1536-1098-74.2.144","DOIUrl":"https://doi.org/10.3959/1536-1098-74.2.144","url":null,"abstract":"Abstract The Portainé mountain catchment, containing the Port Ainé ski resort (Lleida, Spanish Pyrenees), displays active erosional and depositional phenomena caused by periodic torrential floods. These events present a potential risk and incur significant economic losses. In ungauged remote catchments (like Portainé), trees might be the only paleohydrological source of information regarding past floods. Thus, we estimated the temporal and spatial distribution of torrential floods by dendrogeomorphological techniques to assess whether human impact (land-use changes and infrastructure works) affected their frequency and magnitude. One-hundred and sixty-six samples from 67 trees belonging to 10 different species were analyzed; past flood events of the last 50 years were identified by dating and relating evidence between them. Moreover, a detailed geomorphological study was performed and the available historical data compiled. Our multi-evidence analysis provides new insight into the occurrence of paleofloods. Changes in flood frequency since 2006, especially from 2008, suggest that the geomorphological equilibrium has been disturbed, coinciding with both major earthworks within the ski resort and intense but not extraordinary rainfall. This conclusion has important implications for land planning and the design of future projects in the mountain watersheds.","PeriodicalId":54416,"journal":{"name":"Tree-Ring Research","volume":"74 1","pages":"144 - 161"},"PeriodicalIF":1.6,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3959/1536-1098-74.2.144","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45342010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.3959/1536-1098-74.2.210
J. Jevšenak, S. Džeroski, S. Zavadlav, T. Levanič
Abstract Machine learning (ML) is a widely unexplored field in dendroclimatology, but it is a powerful tool that might improve the accuracy of climate reconstructions. In this paper, different ML algorithms are compared to climate reconstruction from tree-ring proxies. The algorithms considered are multiple linear regression (MLR), artificial neural networks (ANN), model trees (MT), bagging of model trees (BMT), and random forests of regression trees (RF). April-May mean temperature at a Quercus robur stand in Slovenia is predicted with mean vessel area (MVA, correlation coefficient with April-May mean temperature, r = 0.70, p < 0.001) and earlywood width (EW, r = –0.28, p < 0.05). Similarly, June-August mean temperature is predicted with stable carbon isotope (δ13C, r = 0.72, p < 0.001), stable oxygen isotope (δ18O, r = 0.32, p < 0.05) and tree-ring width (TRW, r = 0.11, p > 0.05 (ns)) chronologies. The predictive performance of ML algorithms was estimated by 3-fold cross-validation repeated 100 times. In both spring and summer temperature models, BMT performed best respectively in 62% and 52% of the 100 repetitions. The second-best method was ANN. Although BMT gave the best validation results, the differences in the models’ performances were minor. We therefore recommend always comparing different ML regression techniques and selecting the optimal one for applications in dendroclimatology.
{"title":"A Machine Learning Approach to Analyzing the Relationship Between Temperatures and Multi-Proxy Tree-Ring Records","authors":"J. Jevšenak, S. Džeroski, S. Zavadlav, T. Levanič","doi":"10.3959/1536-1098-74.2.210","DOIUrl":"https://doi.org/10.3959/1536-1098-74.2.210","url":null,"abstract":"Abstract Machine learning (ML) is a widely unexplored field in dendroclimatology, but it is a powerful tool that might improve the accuracy of climate reconstructions. In this paper, different ML algorithms are compared to climate reconstruction from tree-ring proxies. The algorithms considered are multiple linear regression (MLR), artificial neural networks (ANN), model trees (MT), bagging of model trees (BMT), and random forests of regression trees (RF). April-May mean temperature at a Quercus robur stand in Slovenia is predicted with mean vessel area (MVA, correlation coefficient with April-May mean temperature, r = 0.70, p < 0.001) and earlywood width (EW, r = –0.28, p < 0.05). Similarly, June-August mean temperature is predicted with stable carbon isotope (δ13C, r = 0.72, p < 0.001), stable oxygen isotope (δ18O, r = 0.32, p < 0.05) and tree-ring width (TRW, r = 0.11, p > 0.05 (ns)) chronologies. The predictive performance of ML algorithms was estimated by 3-fold cross-validation repeated 100 times. In both spring and summer temperature models, BMT performed best respectively in 62% and 52% of the 100 repetitions. The second-best method was ANN. Although BMT gave the best validation results, the differences in the models’ performances were minor. We therefore recommend always comparing different ML regression techniques and selecting the optimal one for applications in dendroclimatology.","PeriodicalId":54416,"journal":{"name":"Tree-Ring Research","volume":"74 1","pages":"210 - 224"},"PeriodicalIF":1.6,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3959/1536-1098-74.2.210","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42272777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-02-22DOI: 10.3959/1536-1098-74.1.132
M. Hughes, E. Cook, T. Osborn, T. Melvin
Keith R. Briffa, 64, died on October 29, 2017. Keith was born December 27, 1952, in Liverpool, United Kingdom. He earned a B.Sc. (Honours) degree in Biological Sciences at the University of East Anglia (UEA) in 1974 and joined the Climatic Research Unit (CRU) there in 1977. He received his Ph.D. from the UEA School of Environmental Sciences in 1984, successfully defending his thesis “Tree-Climate Relationships and Dendroclimatological Reconstruction in the British Isles.” He stayed at CRU for the 40 years of his remarkably productive and significant scientific career, having the title of Emeritus Professor at the time of his passing. Keith showed great breadth of scientific understanding, creativity, rigor, willingness and ability to collaborate and unflinching intellectual honesty. These attributes are clearly evident in all his work, from his Ph.D. dissertation to the most recent of his more than 130 publications. He has been a central figure in the elaboration and testing of new and improved approaches to dendrochronology in general and to dendroclimatology in particular. Especially indispensable contributions include methods for evaluating common signal strength in tree-ring collections, including Expressed Population Signal (EPS) and Subsample Signal Strength (SSS). Keith also investigated methods of tree-ring standardization based onGaussian filters, and later the groundbreaking Regional Curve Standardization (RCS) method.His identification of apparent reduced sensitivity of tree-ring records to temperature at high latitudes in recent decades (“divergence”) stimulated much critical examination and improvement in dendroclimatology. Keith’s research contributed greatly to the analysis of tree-ring networks on regional to global scales and their use in the rigorously tested reconstruction of climate fields based on the method of ‘Orthogonal Spatial Regression’ (OSR) developed in his thesis. He was at the very
Keith R.Briffa，64岁，于2017年10月29日去世。基思1952年12月27日出生于英国利物浦。1974年，他在东安格利亚大学（UEA）获得生物科学学士（荣誉）学位，1977年加入该校气候研究所（CRU）。1984年，他获得了UEA环境科学学院的博士学位，成功地为他的论文“不列颠群岛的树木气候关系和树木气候重建”进行了辩护。在他富有成效和意义的科学生涯中，他在CRU工作了40年，在他去世时获得了名誉教授的头衔。基思表现出了广泛的科学理解、创造力、严谨性、合作意愿和能力，以及坚定的智力诚实。这些特质在他的所有作品中都很明显，从他的博士论文到他130多篇出版物中的最新一篇。他一直是阐述和测试新的和改进的树木年表方法，特别是树木气候学方法的核心人物。特别不可或缺的贡献包括用于评估树环集合中的公共信号强度的方法，包括表达总体信号（EPS）和子样本信号强度（SSS）。Keith还研究了基于高斯滤波器的树环标准化方法，以及后来开创性的区域曲线标准化（RCS）方法。近几十年来，他发现高纬度地区树木年轮记录对温度的敏感性明显降低（“差异”），这激发了树木气候学的许多批判性研究和改进。Keith的研究极大地促进了区域到全球尺度上的树环网络分析，并将其用于基于其论文中开发的“正交空间回归”（OSR）方法的严格测试的气候场重建。他在
{"title":"Keith R. Briffa","authors":"M. Hughes, E. Cook, T. Osborn, T. Melvin","doi":"10.3959/1536-1098-74.1.132","DOIUrl":"https://doi.org/10.3959/1536-1098-74.1.132","url":null,"abstract":"Keith R. Briffa, 64, died on October 29, 2017. Keith was born December 27, 1952, in Liverpool, United Kingdom. He earned a B.Sc. (Honours) degree in Biological Sciences at the University of East Anglia (UEA) in 1974 and joined the Climatic Research Unit (CRU) there in 1977. He received his Ph.D. from the UEA School of Environmental Sciences in 1984, successfully defending his thesis “Tree-Climate Relationships and Dendroclimatological Reconstruction in the British Isles.” He stayed at CRU for the 40 years of his remarkably productive and significant scientific career, having the title of Emeritus Professor at the time of his passing. Keith showed great breadth of scientific understanding, creativity, rigor, willingness and ability to collaborate and unflinching intellectual honesty. These attributes are clearly evident in all his work, from his Ph.D. dissertation to the most recent of his more than 130 publications. He has been a central figure in the elaboration and testing of new and improved approaches to dendrochronology in general and to dendroclimatology in particular. Especially indispensable contributions include methods for evaluating common signal strength in tree-ring collections, including Expressed Population Signal (EPS) and Subsample Signal Strength (SSS). Keith also investigated methods of tree-ring standardization based onGaussian filters, and later the groundbreaking Regional Curve Standardization (RCS) method.His identification of apparent reduced sensitivity of tree-ring records to temperature at high latitudes in recent decades (“divergence”) stimulated much critical examination and improvement in dendroclimatology. Keith’s research contributed greatly to the analysis of tree-ring networks on regional to global scales and their use in the rigorously tested reconstruction of climate fields based on the method of ‘Orthogonal Spatial Regression’ (OSR) developed in his thesis. He was at the very","PeriodicalId":54416,"journal":{"name":"Tree-Ring Research","volume":"74 1","pages":"132 - 133"},"PeriodicalIF":1.6,"publicationDate":"2018-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3959/1536-1098-74.1.132","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49361811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-02-22DOI: 10.3959/1536-1098-74.1.76
M. Islam, Mizanur Rahman, A. Bräuning
Abstract We present the microscopic analysis of growth-ring boundary anatomy of 27 tree species from a moist tropical forest in Bangladesh and evaluate their dendrochronological potential. We observed high inter-species variability in the anatomical features that define growth-ring boundaries. Marginal parenchyma, fibre zones, and thick-walled latewood fibres were identified as the dominant anatomical features delineating growth-ring boundaries. The evaluation of growth-ring boundary distinctness in thin-sections and scanned images revealed that 25 out of 27 studied species (93%) showed distinct to fairly distinct growth-ring boundaries. Cluster analysis of wood anatomical features was used to select an additional 5 species for further investigation. Ring-width series of these species crossdated well within the same tree. Between trees crossdating was also successful in all 5 species. The Gleichläufigkeit (GLK; i.e. the proportion of agreement/disagreement of inter-annual growth tendencies among the trees) varied among species between 0.55 and 0.71. A strong synchronization of tree-ring series between trees suggests that growth rings are annual and influenced by common environmental factors. The derived tree-ring series, estimated tree ages, and growth trajectories underline the high potential of our study area for answering a variety of climatological, ecological and archaeological questions by applying dendrochronology. This study will therefore provide a new endeavor in tropical dendrochronology of South Asian moist tropical forests.
{"title":"Growth-Ring Boundary Anatomy and Dendrochronological Potential in a Moist Tropical Forest in Northeastern Bangladesh","authors":"M. Islam, Mizanur Rahman, A. Bräuning","doi":"10.3959/1536-1098-74.1.76","DOIUrl":"https://doi.org/10.3959/1536-1098-74.1.76","url":null,"abstract":"Abstract We present the microscopic analysis of growth-ring boundary anatomy of 27 tree species from a moist tropical forest in Bangladesh and evaluate their dendrochronological potential. We observed high inter-species variability in the anatomical features that define growth-ring boundaries. Marginal parenchyma, fibre zones, and thick-walled latewood fibres were identified as the dominant anatomical features delineating growth-ring boundaries. The evaluation of growth-ring boundary distinctness in thin-sections and scanned images revealed that 25 out of 27 studied species (93%) showed distinct to fairly distinct growth-ring boundaries. Cluster analysis of wood anatomical features was used to select an additional 5 species for further investigation. Ring-width series of these species crossdated well within the same tree. Between trees crossdating was also successful in all 5 species. The Gleichläufigkeit (GLK; i.e. the proportion of agreement/disagreement of inter-annual growth tendencies among the trees) varied among species between 0.55 and 0.71. A strong synchronization of tree-ring series between trees suggests that growth rings are annual and influenced by common environmental factors. The derived tree-ring series, estimated tree ages, and growth trajectories underline the high potential of our study area for answering a variety of climatological, ecological and archaeological questions by applying dendrochronology. This study will therefore provide a new endeavor in tropical dendrochronology of South Asian moist tropical forests.","PeriodicalId":54416,"journal":{"name":"Tree-Ring Research","volume":"74 1","pages":"76 - 93"},"PeriodicalIF":1.6,"publicationDate":"2018-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3959/1536-1098-74.1.76","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42216848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-02-22DOI: 10.3959/1536-1098-74.1.108
Adriana Beatriz Ortiz-Quijano, Consuelo Cuevas-Cardona, J. Villanueva‐Díaz, L. López-Mata, A. Sánchez‐González
Abstract Growth-ring analysis is a valuable source of information for reconstructing environmental history. In this study, ring-width series of a sample of Fagus grandifolia subsp. mexicana were used to identify the main events that have affected populations of this species. Core samples were extracted in three representative beech forests in Mexico. These are forests where F. grandifolia subsp. mexicana dominates the canopy. A total of 3355 years of growth rings were measured and three ring-width chronologies were generated. Average annual ring widths were similar between the three sites and ranged from 0.98 to 1.08 mm. A pattern of multiple suppressions and releases was observed, mainly associated with local events, but with a slight climatic influence. Correlations between the ring-width index and climate variables were not statistically significant, with the exception of a seasonal January–June precipitation pattern (1982–2001). There has not been a large-scale disturbance of natural or human origin in the beech forests of the state of Hidalgo in the past 150 years, except in El Gosco, where anthropogenic disturbances have increased in the past decade.
{"title":"Dendrochronological Reconstruction of Environmental History of Fagus Grandifolia Subsp. Mexicana in Mexico","authors":"Adriana Beatriz Ortiz-Quijano, Consuelo Cuevas-Cardona, J. Villanueva‐Díaz, L. López-Mata, A. Sánchez‐González","doi":"10.3959/1536-1098-74.1.108","DOIUrl":"https://doi.org/10.3959/1536-1098-74.1.108","url":null,"abstract":"Abstract Growth-ring analysis is a valuable source of information for reconstructing environmental history. In this study, ring-width series of a sample of Fagus grandifolia subsp. mexicana were used to identify the main events that have affected populations of this species. Core samples were extracted in three representative beech forests in Mexico. These are forests where F. grandifolia subsp. mexicana dominates the canopy. A total of 3355 years of growth rings were measured and three ring-width chronologies were generated. Average annual ring widths were similar between the three sites and ranged from 0.98 to 1.08 mm. A pattern of multiple suppressions and releases was observed, mainly associated with local events, but with a slight climatic influence. Correlations between the ring-width index and climate variables were not statistically significant, with the exception of a seasonal January–June precipitation pattern (1982–2001). There has not been a large-scale disturbance of natural or human origin in the beech forests of the state of Hidalgo in the past 150 years, except in El Gosco, where anthropogenic disturbances have increased in the past decade.","PeriodicalId":54416,"journal":{"name":"Tree-Ring Research","volume":"74 1","pages":"108 - 119"},"PeriodicalIF":1.6,"publicationDate":"2018-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3959/1536-1098-74.1.108","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42704983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-02-22DOI: 10.3959/1536-1098-74.1.1
R. Alfaro‐Sánchez, J. Camarero, R. Sánchez‐Salguero, V. Trouet, J. Heras
Abstract Climate models project increasing temperatures, evapotranspiration, and droughts for the Mediterranean Basin, which will trigger more frequent and dangerous fire events. Here, we evaluate the combined effects of drought and wildfire on seasonal tree growth on Aleppo pine stands at the intra- and inter-annual level. Indexed earlywood width (EWI), latewood width (LWI), and latewood proportion (LWPI) series were obtained from unburned and burned stands located at four sites along a precipitation gradient in southeastern Spain. The combined effect of drought in 1994 and 1995 and wildfire in August 1994, negatively impacted seasonal growth in the short term (1994–1999 period) at the site with higher water availability. At the driest site, however, no significant effects were found. We found fewer negative pointer years at the wettest burned stand than at the wettest unburned stand during the post-fire 1994–2012 period, and the opposite pattern was found at the driest site, i.e. more negative pointer years at the driest burned stand than at the driest unburned stand. This result indicates that the drier sites were more sensitive to cumulative impact of drought and wildfire disturbances in the long term, whereas the wetter sites were more sensitive in the short term. Our results demonstrate the seasonal growth plasticity of Aleppo pine to combined disturbances depends on site water availability. This study will help forest managers to implement climate change strategies, such as prescribed fires (controlled low-medium severity fires) to prevent wildfire hazards more efficiently in Aleppo pine stands with high water availability.
{"title":"How do Droughts and Wildfires Alter Seasonal Radial Growth in Mediterranean Aleppo Pine Forests?","authors":"R. Alfaro‐Sánchez, J. Camarero, R. Sánchez‐Salguero, V. Trouet, J. Heras","doi":"10.3959/1536-1098-74.1.1","DOIUrl":"https://doi.org/10.3959/1536-1098-74.1.1","url":null,"abstract":"Abstract Climate models project increasing temperatures, evapotranspiration, and droughts for the Mediterranean Basin, which will trigger more frequent and dangerous fire events. Here, we evaluate the combined effects of drought and wildfire on seasonal tree growth on Aleppo pine stands at the intra- and inter-annual level. Indexed earlywood width (EWI), latewood width (LWI), and latewood proportion (LWPI) series were obtained from unburned and burned stands located at four sites along a precipitation gradient in southeastern Spain. The combined effect of drought in 1994 and 1995 and wildfire in August 1994, negatively impacted seasonal growth in the short term (1994–1999 period) at the site with higher water availability. At the driest site, however, no significant effects were found. We found fewer negative pointer years at the wettest burned stand than at the wettest unburned stand during the post-fire 1994–2012 period, and the opposite pattern was found at the driest site, i.e. more negative pointer years at the driest burned stand than at the driest unburned stand. This result indicates that the drier sites were more sensitive to cumulative impact of drought and wildfire disturbances in the long term, whereas the wetter sites were more sensitive in the short term. Our results demonstrate the seasonal growth plasticity of Aleppo pine to combined disturbances depends on site water availability. This study will help forest managers to implement climate change strategies, such as prescribed fires (controlled low-medium severity fires) to prevent wildfire hazards more efficiently in Aleppo pine stands with high water availability.","PeriodicalId":54416,"journal":{"name":"Tree-Ring Research","volume":"74 1","pages":"1 - 14"},"PeriodicalIF":1.6,"publicationDate":"2018-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3959/1536-1098-74.1.1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48738505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-02-22DOI: 10.3959/1536-1098-74.1.50
Magdalena Opała-Owczarek, P. Owczarek, O. Rahmonov, T. Niedźwiedź
Abstract We are reporting the first dendrochronological dating of timber from Tajikistan. Thirty samples were collected from two old buildings from a village located in the western Pamir-Alay; eight cores were taken from temple. Most of the construction wood was juniper species. The object chronologies crossdated well with the previously published chronology based on living juniper trees from western Pamir-Alay. The results of dating revealed that investigated structures are composed of wood coming from several periods. The oldest pieces of wood dated back to the 11th and 12th Centuries. Most timber samples come from the turn of the 17th and 18th Centuries, which were probably the period of intense development of the Artuch village. Besides dating of the wood samples from these historic structures, our investigation provides the opportunity to extend the currently existing regional tree-ring chronology for future climate reconstruction of the Pamir-Alay and High Asia. Dated sequences were assembled into a 1012-year chronology spanning the period 945–2014 C.E. and strengthened the replication of its earliest part (with critical 0.85 EPS value since the beginning of the 13th Century).
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Abstract We quantified the growth dynamics and climatic responses of three tree species that have dominated Changbai Mountain: Korean pine (Pinus koraiensis), Yeddo spruce (Picea jezoensis), and Erman's birch (Betula ermanii). Standardization curves and moving correlations were used to assess growth rate trends and analyze changes in growth-climate relationships of trees at their upper forest boundaries and individual species elevation limits, respectively. Contrasting growth patterns were observed between trees at each upper forest boundary and species-specific upper elevation limits. Korean pines and Yeddo spruces grew faster at their upper forest boundaries than at their individual species limits. A higher growth rate of Erman's birches at their forest upper boundary only occurred before 1960. Relative to the strong effect of temperature on tree growth at individual upper elevation limits, the stable effect of precipitation and changing effect of temperature on tree growth were observed at the upper forest boundaries. Temperature increases have had a significantly negative effect on Korean pine and Erman's birch since 1980, whereas temperature increases were associated with Yeddo spruce growth. This study elucidated the differential growth patterns and temporal changes in climate–growth relationships of these species between their upper forest boundaries and elevation limits.
{"title":"Sensitivity of Three Dominant Tree Species from the Upper Boundary of Their Forest Type to Climate Change at Changbai Mountain, Northeastern China","authors":"Lushuang Gao, Yun Zhang, Xiaoming Wang, Chunyu Zhang, Yihan Zhao, Lanmei Liu","doi":"10.3959/1536-1098-74.1.39","DOIUrl":"https://doi.org/10.3959/1536-1098-74.1.39","url":null,"abstract":"Abstract We quantified the growth dynamics and climatic responses of three tree species that have dominated Changbai Mountain: Korean pine (Pinus koraiensis), Yeddo spruce (Picea jezoensis), and Erman's birch (Betula ermanii). Standardization curves and moving correlations were used to assess growth rate trends and analyze changes in growth-climate relationships of trees at their upper forest boundaries and individual species elevation limits, respectively. Contrasting growth patterns were observed between trees at each upper forest boundary and species-specific upper elevation limits. Korean pines and Yeddo spruces grew faster at their upper forest boundaries than at their individual species limits. A higher growth rate of Erman's birches at their forest upper boundary only occurred before 1960. Relative to the strong effect of temperature on tree growth at individual upper elevation limits, the stable effect of precipitation and changing effect of temperature on tree growth were observed at the upper forest boundaries. Temperature increases have had a significantly negative effect on Korean pine and Erman's birch since 1980, whereas temperature increases were associated with Yeddo spruce growth. This study elucidated the differential growth patterns and temporal changes in climate–growth relationships of these species between their upper forest boundaries and elevation limits.","PeriodicalId":54416,"journal":{"name":"Tree-Ring Research","volume":"74 1","pages":"39 - 49"},"PeriodicalIF":1.6,"publicationDate":"2018-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3959/1536-1098-74.1.39","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48313736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-02-22DOI: 10.3959/1536-1098-74.1.28
B. Guan, W. Wright, E. Cook
Abstract Since its establishment, tree-ring analysis has benefitted several scientific fields. Because of its many advantages, dendrochronology is a first choice to reconstruct past environmental variability. Two major concerns about the current tree-ring reconstruction paradigm are the subjective choices of detrending functions and the lack of fidelity to data of chronology generation methods. It is difficult to recover the original tree-ring data once they have been detrended and standardized. In this study, ensemble empirical mode decomposition (EEMD) is introduced as an objective high-fidelity stand-alone approach for developing tree-ring chronologies. Basic concepts of EEMD, recommended steps in developing chronologies, and available public domain programs are discussed. To demonstrate the potentials of EEMD for chronology development, two examples are provided, one for climate and the other for streamflow reconstructions. In both examples, EEMD chronologies show higher correlations with the instrumental data and have more power in their spectra than the ones developed based on the current tree-ring reconstruction approach. General usage concerns and cautions are also addressed.
{"title":"Ensemble Empirical Mode Decomposition as an Alternative for Tree-Ring Chronology Development","authors":"B. Guan, W. Wright, E. Cook","doi":"10.3959/1536-1098-74.1.28","DOIUrl":"https://doi.org/10.3959/1536-1098-74.1.28","url":null,"abstract":"Abstract Since its establishment, tree-ring analysis has benefitted several scientific fields. Because of its many advantages, dendrochronology is a first choice to reconstruct past environmental variability. Two major concerns about the current tree-ring reconstruction paradigm are the subjective choices of detrending functions and the lack of fidelity to data of chronology generation methods. It is difficult to recover the original tree-ring data once they have been detrended and standardized. In this study, ensemble empirical mode decomposition (EEMD) is introduced as an objective high-fidelity stand-alone approach for developing tree-ring chronologies. Basic concepts of EEMD, recommended steps in developing chronologies, and available public domain programs are discussed. To demonstrate the potentials of EEMD for chronology development, two examples are provided, one for climate and the other for streamflow reconstructions. In both examples, EEMD chronologies show higher correlations with the instrumental data and have more power in their spectra than the ones developed based on the current tree-ring reconstruction approach. General usage concerns and cautions are also addressed.","PeriodicalId":54416,"journal":{"name":"Tree-Ring Research","volume":"74 1","pages":"28 - 38"},"PeriodicalIF":1.6,"publicationDate":"2018-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3959/1536-1098-74.1.28","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46174825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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