Annual Growth Rings Research Articles

Can secondary osteons be used as ontogenetic indicators in sauropods? Extending the histological ontogenetic stages into senescence

AbstractSauropod bone histology has provided a great deal of insight into the life history of these enormous animals. However, because of high growth rates, annual growth rings are not common in sauropod long bones, so directly measuring growth rates and determining sexual maturity require alternative measures. Histological ontogenetic stages (HOS) have been established to describe the changes in bone histology through development for basal Macronaria and Diplodocoidea, and subsequently for Titanosauria. Despite this, the current HOS model is not able to discriminate bone tissues in late ontogeny, when sauropods had reached asymptotic size and continued to live into senescence but their long bones became extensively remodeled by secondary osteons and all primary bone was destroyed. Here we establish remodeling stages (RS) to characterize the Haversian bone development through ontogeny in eight sauropod taxa (Apatosaurinae,Giraffatitan brancai,Camarasaurusspp.,Dicraeosaurusspp.,Ampelosaurus atacis,Phuwiangosaurus sirindhornae,Magyarosaurus dacus, andAlamosaurus sanjuanensis) and find significant correlation of RS with corresponding femur length (CFL) for the studied taxa, with the exception ofDicraeosaurusandMagyarosaurus. Remodeling stages are based on the maximum number of observable generations of crosscutting osteons from the innermost, mid-, and outermost part of the cortex. The correlation with CFL indicates that secondary osteons present an ontogenetic signal that could extend the histological ontogenetic stages. Remodeling stages also provide additional insight into the changes in histology through ontogeny for Sauropoda. This method has the potential to be used in other taxa, such as thyreophorans and many ornithischians, that develop Haversian tissue through development.

X-ray microdensitometry of wood: A review of existing principles and devices

Wood microdensitometry is the analysis of radial variations of density at the annual or intra-annual growth ring level. Density is related to wood quality, biomass, carbon content, tree growth and climate. Wood microdensitometry is particularly used in dendrochronology and climatology studies. The present study focuses on X-ray based methods used in wood microdensitometry analyses and provides a review of the main available devices. An exhaustive review of 75 works published on this topic in 2014 and 2015 showed that film-based equipment is still commonly used. The three other most popular devices, SilviScan, Itrax and QTRS, are also based on X-ray radiography and deliver results with comparable accuracy, below 50μm per pixel. X-ray tomography (CT) is still rarely used in wood densitometry. Medical CT scanners currently offer a lower accuracy (above 100μm per pixel) that is insufficient in most cases for ring or intra-ring scales. Micro-CT scanners offer good performance at the cost of much longer acquisition and reconstruction times.

Fenología, incremento en diámetro y periodicidad de anillos de crecimiento de Enterolobium cyclocarpum (Jacq.) Griseb (Leguminosae) en Costa Grande, Guerrero, México

In this paper were evaluated the phenological events, the diameter increment and periodicity of growth rings of Enterolobium cyclocarpum (Jacq.) Griseb in Costa Grande, Guerrero, Mexico. Every two months for two years they were studied. At the same time and periods growth diameter was measured using dendrometer bands, the crowns of the trees were measured according to their symmetry and lighting. The periodicity of growth was determined by marks on its vascular cambium and confirming the formation of growth rings. E. cyclocarpum presented its leaves fall late November to late March, flowering from January to May, fruiting from March to May and leaves flushing occurred from March to September. The outbreak of leaves was significantly correlated (P < 0.01) with high temperature. The annual diameter growth was, related to the seasonality of precipitation. The largest increases occurring in categories 25 and 30 cm (P < 0.001), on trees with partially symmetric-symmetrical crowns (P < 0.001) and partially lighting (P < 0.001). As a result of seasonality, an annual growth ring delimited parenchyma and fibers are formed.

Calibration of SilviScan data of Cryptomeria japonica wood concerning density and microfibril angles with NIR hyperspectral imaging with high spatial resolution

Abstract Wood density and microfibril angle (MFA) are strongly correlated with wood stiffness, swelling/shrinkage, and its anisotropy. Understanding the spatial distribution of these data is critical for solid timber applications. In this study, near-infrared (NIR) hyperspectral imaging has been calibrated for evaluation of wood density and MFA in an effective manner. Briefly, five wood samples collected from both normal wood (NW) and compression wood (CW) moieties of two different Cryptomeria japonica trees were analyzed. Partial least squares (PLS) regression analysis was performed to determine the relationship between X-ray densitometry data obtained by SilviScan and NIR spectra, and cross-validation (leave-one-out) approach served for prediction performances. The validation coefficient of determination (r2) between the predicted densities by the NIR technique and the X-ray data was 0.83 with a root mean squared error of cross-validation (RMSECV) of 105.2 kg m−3. Regarding MFA, the r2 was 0.77 and RMSECV 5.36°. Wood density was successfully maped as well as the MFA at a high spatial resolution. As a result, the detection of annual growth ring features and evaluation of aspects of heterogeneous wood quality has been facilitated. The mapping results were visually checked by looking at the difference between earlywood (EW) and latewood (LW) for density and by means of the Mäule color reaction indicating high lignin contents in CW in terms of MFA validation as CWs have high MFA values.

Clonal structure, growth pattern and preemptive space occupancy through sprouting of an invasive tree, Triadica sebifera

ABSTRACTWe investigated clonal structure, growth pattern and colonization through sprouting in the invasive tree species Triadica sebifera on Mt. Mikasa, Nara City, Japan. Genets of T. sebifera were identified by microsatellite DNA analysis. The age of stems was determined by counting annual growth rings. In a 25 × 60-m plot, we found 214 genets among 315 stems ≥130 cm in height. Of these, 23 genets were multistemmed. Numbers of stems on a genet increased with increasing genet age. The size, shape and number of stems indicated that several genets adopted a guerilla growth strategy in which stems are widely spaced along roots. Only one genet seemed to adopt a phalanx growth strategy characterized by high stem density within limited areas. Older stems occurred only in the vicinity of the parental stems of genets. Young stems occurred not only at the leading edge of the genet but also close to the parental stem. Stem size was negatively correlated with the number of younger stems but positively correlated with that of older stems on the same genet. This suggests that stems were physiologically connected and that translocation of photosynthetic products was directed from old to young stems. Physiological integration may allow small stems to persist under low light availability. These findings indicate that urgent measures are required to control the T. sebifera population because the species increases its area of occupancy by vigorous stem sprouting which may compromise the natural forest.

The Influence of Microfibril Angle on the Wood Stiffness Parameters

The cellulose microfibrile angles /MFA/ in tracheids of spruce wood were observed using the polarization microscope treatment. For the wood samples tested, the modulus of elasticity in compression strain was performed. The close dependency of the MFA values on to the parameters of modulus of elasticity was established. The portion of early wood and late wood of each of the annual growth rings was determined using the stereomicroscope, even the content of the cell wall thicknesses was determined using the optical microscope. The dependency of the late wood ratio in the cross section including only the content of the cell wall in the annual growth ring of spruce on to the stiffness parameters was established.

Comparative analysis of the growth of Margaritifera margaritifera (Bivalvia) from different populations of Karelia and Kola Peninsula

Comparative analysis of individual linear growth of Margaritifera margaritifera populations from the Syuskyuyanioki, Nemina, Vuokinioki, Keret (Karelia), and Varzuga (Kola Peninsula) rivers has been performed. Data on the lengths of consecutive annual growth rings on the external shell surface have been obtained. The comparative analysis has been made of two coefficients of the united growth equation, one of which determines the initial growth rate; the other determines growth inhibition. Growth parameters are assumed to vary greatly within each population and differ significantly between different specimens. The values of the coefficients decrease with increasing geographical latitude of the habitat. It is shown that the population in the Syuskyuyanioki River is comparable with respect to the growth constant with the southernmost populations of rivers in Northern Spain.

Ecological Characteristics of Sub-Alpine Coniferous Forest on Banyabong in Mt. Jiri

This study was conducted to elucidate the ecological characteristics of sub-alpine coniferous forest on Banyabong, Mt. Jiri. Soil pH was 4.20. The contents of organic matter, total N, available P and CEC were 14.15%, 0.43%, 10.1 ppm and 17.17 cmolSUP+/SUP/kg, respectively. Sub-alpine coniferous forest had a relatively soil moisture content with 22.9%. According to the results of importance value analysis, Picea jezoensis (42.7) and Abies koreana (34.0) for tree layer, Rhododendron schlippenbachii (25.5) for subtree layer and Tripterygium regelii (18.4) and Rhododendron mucronulatum (16.6) for shrub layer were high, respectively. Shannon’s diversity ranged from 0.3560 to 1.050. Evenness and dominance ranged from 0.398 to 0.733 and 0.267 to 0.601, respectively. A. koreana population had a reverse J-shaped DBH distribution, while P. jezoensis population had a normal DBH distribution. Height growth according to DBH of A. koreana was higher than that of P. jezoensis, which indicate than A. koreana have more effective water use efficiency than P. jezoensis. Annual mean tree ring growth of P. jezoensis and A. koreana showed up 1.792, 1.652, 1.389 mm/yr and 2.081, 1.921, 1.576 mm/yr for small, middle and large diameter tree, respectively.

From structural constraints to hydraulic function in three Vitis rootstocks

Narrow stem size in limiting Vitis rootstocks imposes a morphological constraint on the scion via reduced annual ring size, and thus reduces hydraulic conductivity and subsequently physiological performance and yield. Graft is a union between two separate species or cultivars, which produces a chimera plant with new qualities—as rootstock affects scion growth, yield, and adaptability to different environmental conditions. In Vitis, it is possible to generate rootstock/scion combinations that produce a desired drought stress effect crucial for high-quality wine production, though the mechanisms for such interactions are complex and poorly understood. The current study was done on vines with an identical scion (Vitis vinifera ‘Cabernet Sauvignon’) grafted on three different rootstocks—either Riparia Gloire, Paulsen 1103 or 420A—in attempt to explain the differences in water status by examining the underlying anatomical constraints and calculated theoretical hydraulic conductivity. There was a significant difference in physiological responses and yield between the grafts. Riparia Gloire grafts had the lowest water potentials and the highest quality grapes, together with low root, scion stem, and branch theoretical hydraulic conductivity. In scions grafted on Riparia Gloire, the annual growth rings were significantly narrower than in the other two grafts, causing a significantly lower theoretical hydraulic conductivity per annual ring. The narrow annual ring size in scion stem was imposed by the morphological constraint of the stem size. In hydraulically inferior Riparia Gloire grafts, the difference was disproportionally large, with a wide scion grafted on a very narrow rootstock, and Paulsen 1103 had the smoothest graft union. Our results indicate that the ability to develop stronger drought stress in Vitis grafts depends on rootstock-imposed morphological restriction of hydraulic conductivity.

Morphological and Anatomical Evaluation of Grafted Pinus merkusii

Morphological and anatomical evaluation of grafted P. merkusii have been undertaken to obtain the information about compatible and incompatible symptoms of 18 years old grafts based on morphological observation and microscopic analysis. Samples of compatible and incompatible grafts were obtained from previous research conducted by the Silviculture Departement Team in 1994. Result showed that compatible grafts have normal stem form and secondary growth (diameter growth), but some abnormality symptoms like undulated pattern of annual growth rings, phloem thickening and abnormality resin ducts in inner and middle parts of the union area occurred. Incompatible ones showed abnormality of the stem form, cortex-bark necrosis and swelling in the union area. Microscopic observation showed abnormality of all parts of the union, undulated pattern of annual growth rings, phloem thickening, abnormal resin ducts, low numbers and discontinuity of vascular elements in the union area.

A novel dendrochronological approach reveals drivers of carbon sequestration in tree species of riparian forests across spatiotemporal scales

Aboveground carbon (C) sequestration in trees is important in global C dynamics, but reliable techniques for its modeling in highly productive and heterogeneous ecosystems are limited. We applied an extended dendrochronological approach to disentangle the functioning of drivers from the atmosphere (temperature, precipitation), the lithosphere (sedimentation rate), the hydrosphere (groundwater table, river water level fluctuation), the biosphere (tree characteristics), and the anthroposphere (dike construction). Carbon sequestration in aboveground biomass of riparian Quercus robur L. and Fraxinus excelsior L. was modeled (1) over time using boosted regression tree analysis (BRT) on cross-datable trees characterized by equal annual growth ring patterns and (2) across space using a subsequent classification and regression tree analysis (CART) on cross-datable and not cross-datable trees. While C sequestration of cross-datable Q. robur responded to precipitation and temperature, cross-datable F. excelsior also responded to a low Danube river water level. However, CART revealed that C sequestration over time is governed by tree height and parameters that vary over space (magnitude of fluctuation in the groundwater table, vertical distance to mean river water level, and longitudinal distance to upstream end of the study area). Thus, a uniform response to climatic drivers of aboveground C sequestration in Q. robur was only detectable in trees of an intermediate height class and in taller trees (>21.8m) on sites where the groundwater table fluctuated little (≤0.9m). The detection of climatic drivers and the river water level in F. excelsior depended on sites at lower altitudes above the mean river water level (≤2.7m) and along a less dynamic downstream section of the study area. Our approach indicates unexploited opportunities of understanding the interplay of different environmental drivers in aboveground C sequestration. Results may support species-specific and locally adapted forest management plans to increase carbon dioxide sequestration from the atmosphere in trees.

Spatiotemporal factors affecting bark stripping of conifer trees by Asiatic black bears (Ursus thibetanus) in Japan

Bark stripping by Asiatic black bears (Ursus thibetanus) has a serious impact on conifer plantations in Japan, resulting in physical damage to the tree trunks and reduction of the value of the timber. The aim of this study was to clarify whether these plantations are more prone to damage by bears at particular times and sites, to more effectively prevent this damaging behavior. The study was conducted at Kusaki University Forest of Tokyo University of Agriculture and Technology in Gunma Prefecture, central Japan. To determine where, when, and how frequently bears strip the bark, we established circular plots in each of 65 stands and felled all trees that had been damaged by bears. In total, we felled 1639 damaged trees, analyzed 1490 samples (Cryptomeria japonica: 1236, Chamaecyparis obtusa: 254) across the 65 study stands, and calculated the timing of bark stripping for each by counting the number of annual growth rings in each tree. Generalized linear mixed models were then used to examine the effects of various spatiotemporal factors on bark stripping. In terms of temporal variation, we found no relationships between the occurrence of bark stripping by bears and the meteorological conditions from the previous November to the previous March. In terms of spatial variation, there was no relationship between the occurrence of bark stripping by bears and the environmental characteristics of the stands. We did, however, find that stands that experienced bear damage in the previous year were more prone to experiencing bear damage in the current year, and furthermore, the rate at which damage of trees spread during the 10years after the first occurrence of a damaged tree was significantly faster in young stands. These findings will allow forest managers to predict the conditions that make conifer stands more prone to bear damage, allowing them to make effective forest management plans. Additionally, to reduce bear damage, foresters should focus on direct protection efforts that they would like to protect from bears.

Especies nativas del matorral espinoso del noreste mexicano con posibilidades de aprovechamiento industrial

Las especies maderables del matorral mexicano han sido menospreciadas para su uso comercial, utilizándose mayoritariamente para cercas, leña y carbón, y en menor grado para la fabricación de muebles rústicos. Con este trabajo se pretende ampliar el reducido campo de aprovechamiento industrial de la madera de cuatro especies típicas del matorral espinoso del noreste de México a través del estudio de su anatomía microscópica y la determinación de sus propiedades físico-mecánicas. Las especies estudiadas son barreta (Helietta parvifolia (Gray ex Hemsl.) Benth), canelón (Melia azedarach L.), ébano (Ebenopsis ebano (Berl.) Barneby &amp; Grimes) y tenaza (Havardia pallens ( Benth.) Britt. &amp; Rose). Las propiedades físico-mecánicas determinadas fueron densidad, porcentaje de contracción y expansión, módulo de elasticidad y resistencia a la flexión (módulo de ruptura, MOR). Los resultados muestran que la barreta es una madera de densidad alta, flexible y de fácil secado caracterizado por una contracción baja. El canelón exhibe una densidad comparativa mayor a la que se observa comúnmente en el pino (a pesar de su crecimiento rápido) teniendo anillos anuales anchos, bajo porcentaje de contracción, alta resistencia al ataque de insectos y siendo su secado fácil, tal como lo es su trabajabilidad. El ébano muestra tener una alta densidad, volviéndose muy duro durante su secado (a tal grado que solo tiene buena trabajabilidad cuando se encuentra en condición verde), agrietándose si el secado se realiza de manera rápida. El duramen de esta especie es muy resistente al ataque de insectos. La tenaza es de fácil secado y tiene alta flexibilidad en condición verde, siendo de baja resistencia al ataque de insectos.

Informing Conservation: Towards 14C Wiggle-Matching of Short Tree-Ring Sequences from Medieval Buildings in England

AbstractThis study tested whether accurate dating by accelerator mass spectrometry (AMS) radiocarbon wiggle-matching of short tree-ring series (~30 annual rings) in the Medieval period could be achieved. Scientific dating plays a central role in the conservation of historic buildings in England. Precise dating helps assess the significance of particular buildings or elements of their fabric, thus allowing us to make informed decisions about their repair and protection. Consequently, considerable weight, both financial and legal, can be attached to the precision and accuracy of this dating. Dendrochronology is the method of choice, but in a proportion of cases this is unable to provide calendar dates. Hence, we would like to be able to use 14C wiggle-matching to provide a comparable level of precision and reliability, particularly on shorter tree-ring sequences (~30 annual growth rings) that up until now would not routinely be sampled. We present the results of AMS wiggle-matching five oak tree-ring sequences, spanning the period covered by the vast majority of surviving Medieval buildings in England (about AD 1180–1540) when currently we have only decadal and bidecadal calibration data.

ESTUDIO DE LOS ANILLOS DE CRECIMIENTO DE Cordia alliodora (Ruiz &amp; Pav.) EN COLOMBIA

&lt;p&gt;&lt;em&gt;Cordia alliodora&lt;/em&gt; tiene un alto valor ecológico y económico en la formación de bosque seco tropical de Colombia. En este estudio se documentó la relación entre el monto de precipitación anual, temperatura media anual y el índice de oscilación del sur (SOI) con los anillos anuales de crecimiento de 28 individuos de &lt;em&gt;C. alliodora&lt;/em&gt; con base en la aplicación de la metodología dendrocronológica estándar. &lt;em&gt;C. alliodora &lt;/em&gt;registró anillos anuales de crecimiento demarcados por la porosidad semicircular y el parénquima terminal. La cronología construida cubrió un período de 70 años (1944-2013). El crecimiento radial de &lt;em&gt;C. alliodora&lt;/em&gt;, representado a través de la función matemática de Gompertz, estuvo influenciado positivamente por el monto de precipitación anual y negativamente por la temperatura media anual. No se encontró influencia de los años con la presencia del fenómeno de El Niño (años secos). La cronología residual (1946-2013) mostró un ciclo de activación del crecimiento de 3.3 años vinculados al monto de precipitación anual y a la temperatura media anual. Los resultados sobre el índice de crecimiento muestran que &lt;em&gt;C. alliodora&lt;/em&gt; alcanzaría el máximo crecimiento diamétrico a los 65 años con 205.5 cm. &lt;em&gt;&lt;/em&gt;&lt;/p&gt;

Quantitative Wood Anatomy-Practical Guidelines.

Quantitative wood anatomy analyzes the variability of xylem anatomical features in trees, shrubs, and herbaceous species to address research questions related to plant functioning, growth, and environment. Among the more frequently considered anatomical features are lumen dimensions and wall thickness of conducting cells, fibers, and several ray properties. The structural properties of each xylem anatomical feature are mostly fixed once they are formed, and define to a large extent its functionality, including transport and storage of water, nutrients, sugars, and hormones, and providing mechanical support. The anatomical features can often be localized within an annual growth ring, which allows to establish intra-annual past and present structure-function relationships and its sensitivity to environmental variability. However, there are many methodological challenges to handle when aiming at producing (large) data sets of xylem anatomical data. Here we describe the different steps from wood sample collection to xylem anatomical data, provide guidance and identify pitfalls, and present different image-analysis tools for the quantification of anatomical features, in particular conducting cells. We show that each data production step from sample collection in the field, microslide preparation in the lab, image capturing through an optical microscope and image analysis with specific tools can readily introduce measurement errors between 5 and 30% and more, whereby the magnitude usually increases the smaller the anatomical features. Such measurement errors—if not avoided or corrected—may make it impossible to extract meaningful xylem anatomical data in light of the rather small range of variability in many anatomical features as observed, for example, within time series of individual plants. Following a rigid protocol and quality control as proposed in this paper is thus mandatory to use quantitative data of xylem anatomical features as a powerful source for many research topics.

Dendrochronology and extreme pointer years in the tree-ring record (AD 1951–2011) of polar willow from southwestern Spitsbergen (Svalbard, Norway)

Greater warmth and precipitation over the past several decades in the High Arctic, as recorded in meteorological data, have caused shrub expansion and affected growth ring widths. The main aim of the study was to develop a tree-ring chronology of polar willow (&lt;i&gt;Salix polaris&lt;/i&gt; Wahlenb.) from southwest Spitsbergen, attempt to explain its extreme pointer years (extremely low value of growth-ring widths) and to demonstrate the dendrochronological potential of this species. This plant is a deciduous, prostrate, creeping dwarf shrub that produces anatomically distinct annual growth rings with the consistent ring width variation. After using serial sectioning we developed rigorously cross-dated ring width chronology covering the period 1951–2011. Since the beginning of the 1980s an increase of the mean and maximum growth ring width has been observed which is consistent with the increase of both temperature and precipitation in the Arctic reported from meteorological sources. Nine negative extreme years were distinguished and explained by complex hydroclimatic drivers, which highlight the importance of availability of moisture from snowpack and spring precipitation. An additional negative factor present in the years with very low dwarf shrubs growth is rapid thawing and fast freezing during winter as well as low sunshine duration. Our results contradict the prior assumption that inter-annual tree growth variability of dwarf shrubs from polar regions is controlled simply by temperature.

Biological Basis of Tree-Ring Formation: A Crash Course.

Wood is of crucial importance for man and biosphere. In this mini review, we present the fundamental processes involved in tree-ring formation and intra-annual dynamics of cambial activity, along with the influences of the environmental factors. During wood formation, new xylem cells produced by the cambium are undergoing profound transformations, passing through successive differentiation stages, which enable them to perform their functions in trees. Xylem cell formation can be divided in five major phases: (1) the division of a cambial mother cell that creates a new cell; (2) the enlargement of this newly formed cell; (3) the deposition of its secondary wall; (4) the lignification of its cell wall; and finally, (5) its programmed cell death. In most regions of the world cambial activity follows a seasonal cycle. At the beginning of the growing season, when temperature increases, the cambium resumes activity, producing new xylem cells. These cells are disposed along radial files, and start their differentiation program according to their birth date, creating typical developmental strips in the forming xylem. The width of these strips smoothly changes along the growing season. Finally, when climatic conditions deteriorate (temperature or water availability in particular), cambial activity stops, soon followed by cell enlargement, and later on by secondary wall deposition. Without a clear understanding of the xylem formation process, it is not possible to comprehend how annual growth rings and typical wood structures are formed, recording normal seasonal variations of the environment as well as extreme climatic events.

Dendrochronology of young Swietenia macrophylla and the variation of its growth response to the past wet climate in Bengkulu, Indonesia

Susatya A, Yansen. 2016. Dendrochronology of young Swietenia macrophylla and the variation of its growth response to the past wet climate in Bengkulu, Indonesia. Biodiversitas 17: 466-472. Dendrochronology had long been studied in temperate regions to know tree growth responses to the past climate, and to predict the future effects of climate change. In the wet tropics, dendrochronology studies were rarely carried out because of the lack of distinct annual growth rings or wide variation of growth ring forms. Our research was aimed to know the variations of width of growth rings, and growth response of young Big-Leaf Mahogany (Swietenia macrophylla) to the past wet climate in Bengkulu, Indonesia. Wood disc specimens of cross sections were collected from seven different mahogany trees from campus forest, University of Bengkulu, and then were dried, sanded, and digitally photographed. Growth rings were measured to the nearest 0.001 cm with ImageJ software. The annual ring width data were cross-dated visually by synchronizing and aligning the width patterns of all wood specimens. The results showed that the average of annual growth rings varied from 0.679 cm/year to 1.047 cm/year, and was not significantly different among trees. The width of growth ring of Big-Leaf Mahogany trees demonstrated periodicity through ages, and increased until 9 years old and then started to decline. Individual tree responded differently to climate through out the ages. In the stand level, the average annual growth ring was very sensitive to climate, and positively correlated to rainfall in the first six years, but was independent to rainfall in the past five years. It was speculated that local environments and ecological processes were attributed to obscure the influence of rainfall to the annual growth ring of the older stand.

Determination of Growth Rate and Age Structure of &lt;i&gt;Boswellia papyrifera&lt;/i&gt; from Tree Ring Analysis: Implications for Sustainable Harvest Scheduling

Boswellia papyrifera is a multipurpose deciduous species that grows in Combretum – Terminalia deciduous woodlands of Ethiopia. It is widely known for its commercial frankincense production. The B. papyrifera woodland is under a problematic state of population decline due to heavy encroachment and unsustainable tapping. To sustainably manage such a sensitive ecosystem needs exact knowledge of growth rates and age structure of trees where such information on tropical trees under natural condition is rather poor. In this study growth rate and age of B. papyrifera was determined from tree ring analysis. The study was carried out in Lemlem Terara, Metema district, Ethiopia. The mean annual diameter growth rate of B. papyrifera derived from the mean ring-width is 2.32mm and varies among sample trees. All sampled trees showed a comparable general growth trend which can be divided into three phases – i) good growth in the beginning, ii) phase with depression in middle and iii) increase in ring width. The average age of B. papyrifera trees growing in the study site is estimated to be about 75 years. Although there is strong correlation between diameter of a tree and age, the result from this study highlighted that age-size relations should be used cautiously as the diameter may not reflect the true age. The result from this study is important input to develop strategic plan for the species regarding tapping frequency and intensity as per the annual increment of the species. For further dendrochronological studies of the species, it is recommended to take samples from different size classes and slope gradients for better and reliable results. In future, the use of tree ring analysis as a tool to understand growth dynamics and age structure of trees species, and their response to climate variability should be strengthen in Ethiopian. Keywords: Boswellia papyrifera, Annual growth rings, Diameter growth rate, Age structure, Ethiopia.