Scientific merits and analytical challenges of tree-ring densitometry

R.W. was supported by NERC grant NE/K003097/1.X-ray microdensitometry on annually-resolved tree-ring samples has gained an exceptional position in last-millennium paleoclimatology through the maximum latewood density parameter (MXD), but also increasingly through other density parameters. For fifty years, X-ray based measurement techniques have been the de facto standard. However, studies report offsets in the mean levels for MXD measurements derived from different laboratories, indicating challenges of accuracy and precision. Moreover, reflected visible light-based techniques are becoming increasingly popular and wood anatomical techniques are emerging as a potentially powerful pathway to extract density information at the highest resolution. Here we review the current understanding and merits of wood density for tree-ring research, associated microdensitometric techniques, and analytical measurement challenges. The review is further complemented with a careful comparison of new measurements derived at 17 laboratories, using several different techniques. The new experiment allowed us to corroborate and refresh ?long-standing wisdom?, but also provide new insights. Key outcomes include; i) a demonstration of the need for mass/volume based re-calibration to accurately estimate average ring density; ii) a substantiation of systematic differences in MXD measurements that cautions for great care when combining density datasets for climate reconstructions; and iii) insights into the relevance of analytical measurement resolution in signals derived from tree-ring density data. Finally, we provide recommendations expected to facilitate future inter-comparability and interpretations for global change research.Publisher PDFPeer reviewe

Climate signals in tree-ring width, density and delta13C from larches in Eastern Siberia (Russia)

We present the first and longest (413 years) dataset on stable carbon isotope ratios in tree-ring cellulose (delta C-13), tree-ring width (TRW), and maximum latewood density (MXD) obtained from larch trees growing on permafrost under continental climate in the Suntar Khayata mountain ridge in Eastern Siberia (Russia). With this first study we calibrate tree-ring parameters against climate quantities, and based on these results assess the potential added value of MXD and especially of delta C-13 complementing TRW analysis for future climate reconstruction purposes. delta C-13 chronologies were corrected for human induced changes in atmospheric CO2 since AD 1800. Two different approaches were compared i) a correction referring merely to the decline in atmospheric delta C-13 (delta C-13(atm)) and ii) a correction additionally accounting for the increase in atmospheric partial pressure of CO2. delta C-13 chronologies are characterized by strong signal strength with only 4 trees representing the population signal at the site (mean inter-series correlation = 0.71 and EPS = 0.90). delta C-13 variation shows low similarity to TRW and MXD, while correlation between TRW and MXD is highly significant. Correlation analysis of tree-ring parameters with gridded instrumental data (Climate Research Unit, CRU TS 2.1) over the AD 1929-2000 calibration period demonstrates that TRW and MXD react as reported from other sites at cold and humid northern latitudes: precipitation plays no significant role, but strong dependencies on monthly mean, maximum and minimum temperatures, particularly of the current summer (June to August), are found (up to r=0.60, p<0.001). Combining instrumental data to a summer season mean (JJA) and TRW and MXD to a growth parameter mean (TRW+MXD), clearly shows the importance of the number of frost days and minimum temperatures during summer (r=0.67, p <0.001) to dominate tree growth and highlights the potential for climate reconstruction. Carbon isotope fixation in tree rings is obviously less controlled by temperature variables. In particular, the frost days and minimum temperature have a much smaller influence on delta C-13 than on tree growth. delta C-13 strongly reacts to current-year July precipitation (r=-0.44, p<0.05) and June-July maximum temperature (r=0.46, p<0.001). All significant (p<0.05) correlation coefficients are higher when using the corrected delta C-13 chronology considering an additional plant physiological response on increasing atmospheric CO2 concentration, than using the chronology corrected for delta C-13(atm) changes alone. Spatial distribution of correlations between tree-ring data and climate variables for Eastern Siberia indicates that the summer temperature regime in the studied region is mostly influenced by Arctic air masses, but precipitation in July seems to be brought out from the Pacific region. Both the combined TRW+MXD record and the (513 C record revealed a high reconstruction potential for summer temperature and precipitation, respectively, particularly on decadal and longer-term scales. (C) 2008 Elsevier B.V. All rights reserved

ИНФОРМАЦИОННАЯ СИСТЕМА «ВСЕРОССИЙСКИЙ РЕЕСТР ГРЫЖ»

Hernia is a widespread and common disease. In recent years, the effectiveness of surgical treatment has remained at the same level, despite the introduction of various surgical procedures, the development of endovideo surgical approaches, and the use of synthetic materials. The purpose of this study is to create the structure of the information system “All-Russian hernia registry”. A design solution has been developed, within the framework of which the categories of users are distinguished and the functionality is delineated for each category. This distinction allows you to conveniently structure information. A card is generated for each patient. It contains links to each hernia of this patient, corresponding to this operation and treatment. Also in the patient's card information is formalized that can have an indirect effect on the occurrence of a hernia. For example, risk factors contain information about bad habits of a sports or sedentary lifestyle. There are data of concomitant diseases and drug intolerances in the patient profile. The questionnaire also indicates the patient's place of residence, which from an economic point of view can affect the patient's work and lifestyle. All this information for a group of patients forms statistical ratings, makes information more accessible to patients and stimulates hospitals to develop modern technologies that improve the quality of surgical treatment, and to quickly spread positive experience.Грыжа является широко распространённым и часто встречающимся заболеванием. В последние годы эффективность оперативного лечения остаётся на одном уровне, несмотря на введение различных методик операций, разработку эндовидеохирургических доступов, применение синтетических материалов. Целью этого исследования является создание структуры информационной системы «Всероссийский реестр грыж». Разработано проектное решение, в рамках которого выделены категории пользователей и для каждой категории разграничены функциональные возможности. Такое разграничение позволяет удобным образом структурировать информацию. Формируется карта на каждого пациента, в которой закреплены ссылки на каждую грыжу этого пациента, соответствующие этому операции и лечение. Также в карте пациента формализована его личная информация и сведения, которые могут оказывать косвенное воздействие на возникновение грыжи. Например, факторы риска содержат сведения о вредных привычках спортивном или сидячем образе жизни. Есть в анкете пациента данные о сопутствующих заболеваниях и непереносимости лекарств. Также в анкете указано место проживание пациент, которое с экономической точки зрения может влиять на работу и образ жизни пациента. Все эти сведения для группы пациентов образуют статистические рейтинги, делают информацию более доступной для пациентов и стимулируют больницы к развитию современных технологий, улучшающих качество оперативного лечения, к быстрому распространению положительного опыта

The relationship between needle sugar carbon isotope ratios and tree rings of larch in Siberia

Significant gaps still exist in our knowledge about post-photosynthetic leaf level and downstream metabolic processes and isotopic fractionations. This includes their impact on the isotopic climate signal stored in the carbon isotope composition (delta C-13) of leaf assimilates and tree rings. For the first time, we compared the seasonal delta C-13 variability of leaf sucrose with intra-annual, high-resolution delta C-13 signature of tree rings from larch (Larix gmelinii Rupr.). The trees were growing at two sites in the continuous permafrost zone of Siberia with different growth conditions. Our results indicate very similar low-frequency intra-seasonal trends of the sucrose and tree ring delta C-13 records with little or no indication for the use of 'old' photosynthates formed during the previous year(s). The comparison of leaf sucrose delta C-13 values with that in other leaf sugars and in tree rings elucidates the cause for the reported C-13-enrichment of sink organs compared with leaves. We observed that while the average delta C-13 of all needle sugars was 1.2% more negative than delta C-13 value of wood, the delta C-13 value of the transport sugar sucrose was on an average 1.0% more positive than that of wood. Our study shows a high potential of the combined use of compound-specific isotope analysis of sugars (leaf and phloem) with intra-annual tree ring delta C-13 measurements for deepening our understanding about the mechanisms controlling the isotope variability in tree rings under different environmental conditions.201

Climatic responses of tree-ring widths of Larix gmelinii on contrasting north-facing and south-facing slopes in central Siberia

The original publication is available at www.springerlink.com.ArticleJournal of Wood Science. 53(2): 87-93 (2007)journal articl