Ring Wood Research Articles

Comparison between neural networks and partial least squares for intra-growth ring wood density measurement with hyperspectral imaging

In this paper, a procedure for transforming hyperspectral imaging information into intra-growth ring wood densities is presented. Particular focus was given to comparing the neural network and Partial Least Squares Regression (PLSR) processing methods. The hyperspectral measurements were performed in a wavelength range of 380–1028nm, with a spatial separation of 79μm. The study employed 34 samples from the same number of Pinus pinea tree samples. Density values were analyzed at a total of 34,093 positions in the samples. For neural networks, the mean absolute percentage error (MAPE) and standard deviation of absolute percentage error (StdAPE) values were 6.49% and 5.43%, respectively. For the PLSR method the MAPE and StdAPE were 6.87% and 5.70%, respectively. The neural networks allow reducing the percentage of sample positions with large errors. The proposed method for density measurement can be used for dendrochronology and dendroclimatology.

Usporedba momenta loma kutnog spoja izvedenoga upotrebom različitih ljepila

The main goal of this research is to determine the most appropriate adhesive to fix angular joints with wooden ring for manufacturing window frames. The joint with wooden ring is the result of Slovenian experience and is protected by international patent. The destructive strength of angular joints adhered with different glues was tested by the tensile-testing machine. Polyvinyl acetate glue of the D3 group was found to be the most appropriate from the point of view of strength. The biggest advantage of using a joint with wooden ring lies in the possibility of manufacturing wooden frames from finished elements. In this way, the process of manufacturing a window ends after assembling its parts. It is, therefore, very important to choose the right glue that can completely fill the junction and cover the whole unprotected front part of the joint. For this purpose, polyurethane glues were used in the experiment, as they slightly expand during the hardening phase.

Analysis of spatial and temporal dynamics of xylem refilling in Acer rubrum L. using magnetic resonance imaging.

We report results of an analysis of embolism formation and subsequent refilling observed in stems of Acer rubrum L. using magnetic resonance imaging (MRI). MRI is one of the very few techniques that can provide direct non-destructive observations of the water content within opaque biological materials at a micrometer resolution. Thus, it has been used to determine temporal dynamics and water distributions within xylem tissue. In this study, we found good agreement between MRI measures of pixel brightness to assess xylem liquid water content and the percent loss in hydraulic conductivity (PLC) in response to water stress (P50 values of 2.51 and 2.70 for MRI and PLC, respectively). These data provide strong support that pixel brightness is well correlated to PLC and can be used as a proxy of PLC even when single vessels cannot be resolved on the image. Pressure induced embolism in moderately stressed plants resulted in initial drop of pixel brightness. This drop was followed by brightness gain over 100 min following pressure application suggesting that plants can restore water content in stem after induced embolism. This recovery was limited only to current-year wood ring; older wood did not show signs of recovery within the length of experiment (16 h). In vivo MRI observations of the xylem of moderately stressed (~-0.5 MPa) A. rubrum stems revealed evidence of a spontaneous embolism formation followed by rapid refilling (~30 min). Spontaneous (not induced) embolism formation was observed only once, despite over 60 h of continuous MRI observations made on several plants. Thus this observation provide evidence for the presence of naturally occurring embolism-refilling cycle in A. rubrum, but it is impossible to infer any conclusions in relation to its frequency in nature.

Plan B for Stimulating Stem Cell Division

Plan B for Stimulating Stem Cell Division

The Everyday Work of Lists

The Everyday Work of Lists

Radial distribution of carbohydrate reserves in the trunk of declining European beech trees (Fagus sylvatica L.)

European beech (Fagus sylvatica L.) is considered threatened by anticipated climate change, but the physiological causes of potential beech decline or mortality remains poorly understood. The purpose of the present study was to fuel debate about the assumption that carbohydrate depletion is involved in the decline of mature European beech. The health status of beech trees from a severely declining stand was visually assessed by examining their crown condition. Content and radial distribution of non-structural carbohydrates (starch and soluble carbohydrate) were analyzed in the trunks and compared to those reported earlier in trunks of healthy beech trees. The distribution of carbohydrate in the beech trunks recorded here seemed affected by decline. We found a stronger radial decrease of starch content than those reported earlier for healthy beech trees. Carbohydrate reserves appear partially maintained in the outermost rings while starch depletion occurred in older wood rings in declining trees that may be able to mobilize carbohydrate reserves from older wood rings in response to successive climatic constraints.

The cost of myrmecophytism: insights from allometry of stem secondary growth

Plant defence traits against herbivores incur production costs that are usually difficult to measure. However, estimating these costs is a prerequisite for characterizing the plant defence strategy as a whole. Myrmecophytes are plants that provide symbiotic ants with specialized nesting cavities, called domatia, in exchange for protection against herbivores. In the particular case of stem domatia, production of extra wood seems to be the only associated cost, making this indirect defence trait a particularly suitable model for estimating the cost of defence. Measurements were made of growth pattern and cumulative production cost of domatia over secondary growth in the myrmecophyte Leonardoxa africana subsp. africana, whose internodes display both a solid basal segment and a hollow distal part (the domatium), thus allowing paired comparison of investment in wood. Previous studies showed that 'overconstruction' of the hollow part of internodes during primary growth is needed for mechanical support. In this study, it is shown that the relationship between the woody cross-sectional area of the solid and hollow parts of internodes is negatively allometric at the beginning of secondary growth and nearly isometric later on. Thus, in hollow stems, the first phase of slow secondary growth compensates for the 'overconstruction' of the ring of wood during primary growth. Moreover, the cumulative production cost of a domatium (estimated as the additional volume of wood required for a hollow stem compared with a solid one) is very high at the beginning of secondary growth and then quickly tends to zero. Making domatia incurs high costs early in ontogeny, costs that are then amortized later in development of stems and of individual plants. Characterizing ontogenetic variation of the net cost of this peculiar defence mechanism will help us build more accurate theoretical models of resource allocation in myrmecophytes.

J-integral evaluation in cracked wood specimen using the mark tracking method

In this paper, an experimental analysis of the fracture parameters via the invariant J-integral for a cracked specimen made of wood is presented. The experimental test is realized using a sample made of Douglas fir loaded in opening mode. The sample geometry is a mix between the single edge notch and wedge splitting specimens, and the crack advances in the radial-longitudinal system, parallel to the wood rings. By using the optical mark tracking method, the displacement field evolution close to the crack tip is recorded during the test. The stress and strain fields are calculated using a finite element model generated from the experimental displacement fields. Further, the energy release rate is evaluated for different circular paths or crowns defined around the crack tip and for different loading values.

Modulus of elasticity and hardness of compression and opposite wood cell walls of Masson pine

Compression wood is commonly found in Masson pine. To evaluate the mechanical properties of the cell wall of Masson pine compression and opposite wood, nanoindentation was used. The results showed that the average values of hardness and cell wall modulus of elasticity of opposite wood were slightly higher than those of compression wood. With increasing age of the annual ring, the modulus of elasticity showed a negative correlation with microfibril angle, but a weak correlation was observed for hardness. In opposite and compression wood from the same annual ring, the differences in average values of modulus of elasticity and hardness were small. These slight differences were explained by the change of microfibril angle (MFA), the press-in mode of nanoindentation, and the special structure of compression wood. The mechanical properties were almost the same for early, transition, and late wood in a mature annual ring of opposite wood. It can therefore be inferred that the average modulus of elasticity (MOE) and hardness of the cell walls in a mature annual ring were not being affected by cell wall thickness.

Tree-ring Climatology of Larix gmelinii in Maoershan Region,Northeastern China

Through collecting the meteorological data,sampling and standardizing the data of tree rings of larch(Larix gmelinii),the climatic changes in Maoershan region were analyzed and their influences on tree ring features were studied in this paper.In the past 50 years,significant increases in temperature were found(p0.05),i.e.about 0.4℃ per decade in average annual temperature,0.3℃ per decade in average annual maximum temperature as well as 0.5℃ per decade in annual average minimum temperature were observed.However,no significant change in annual precipitation was found(p0.05).Average monthly temperature(average temperature,average maximum temperature,average minimum temperature) also showed increasing tendencies and the most significant month was in February of the winter,about 0.9-1℃ per decade.Much smaller temperature increases,ca.0.2-0.7℃ per decade was found in June to August of the summer).No significant change in monthly precipitation was found in most months(p0.05).During the coming climate warming,widths of early and whole tree rings(p0.05) might be decreased with the temperature increment in summer(June to July),while widths of early and the growth of tree rings would increase with the temperature increases in spring(May).The width of late might be increased with the temperature increases in autumn(September).These might cause the non-obvious change in ring width with annual temperature changes(p0.05).Although non-significant changes in precipitations,the significant correlations between annual precipitation and variable tree rings indices indicated the growths of early wood and whole tree rings might be positivity affected by the amount of annual precipitations.Considering the warming trend of the climate change is significant in northeast China in future but the rainfall does not.The growth of tree rings caused by spring and autumn temperatures could be offseted by too high temperatures in summer which inhibited the tree ring growth.Therefore,the influence on the radial growth of the Larix might be little.

Evening Fire

Evening Fire Eric Trethewey (bio) It starts slowly, gutters at the edges,and then the paper flares up fiercelyinto bright flames before subsidingto the slow combustion of damp wood. But it persists in spite of all, multipliesin intensity, until becoming at last allwe expected, warming the room, our faces,our hands, and the chill between our shoulders. What more might we ask for nowbut the blessing of words to hold back the dark,the steady burn, the recollection of sunlight,like memory, stacked up in the rings of wood? [End Page 144] Eric Trethewey Eric Trethewey is a native of Nova Scotia who lives at the foot of MacAfee's Knob in Catawba, Virginia, and teaches at Hollins University. He is the author of six books of poetry. His publication credits include The Atlantic Monthly, Paris Review, Poetry, Kenyon Review, and Sewanee Review. Copyright © 2012 Berea College

A Comparison of earlywood–latewood Demarcation Methods – A case study in Loblolly PINE

Demarcating the transition from earlywood (EW) to latewood (LW) is important for accurately estimating the width of both wood types within an annual ring, their respective densities and the proportion of LW within an annual ring. Different methods have been used to define the transition from EW to LW and include Mork’s index, the threshold density method and the inflection point method. In loblolly pine (Pinus taeda L.) a threshold value of 480 kg/m3 (basic density) has conventionally been used to demarcate EW from LW. In this study the three methods: a threshold density of 480 kg/m3, the inflection point method and Mork’s index were used to define the point at which EW transitioned to LW using annual rings for 20 loblolly pine breast height increment cores. Significant correlation was observed among the three methods in identifying the demarcation point. However, the results indicated that EW-LW demarcation points identified using the three methods in juvenile wood rings were different to mature wood rings; with the most pronounced differences being observed for Mork’s index.

Variation of measured cross-sectional cell dimensions and calculated water vapor permeability across a single growth ring of spruce wood

A statistical study of the cell dimensions in a growth ring of spruce along the radial and tangential directions is performed. The data are used to study the variation of the cell vapor permeability in the growth ring. Studying cell rows within one growth ring, the frequency distributions of the cell wall thickness in the radial direction and of the lumen dimension in the tangential direction are found to be both unimodal. In contrast, the frequency distributions of these dimensions in the other directions are bimodal, where the different modes can be attributed to earlywood and latewood. Analysis of the bimodal distributions results in the determination of threshold values of cell wall thickness and the lumen dimension for earlywood and latewood tracheids. The cell dimensions are used to predict cell porosity and water vapor permeability distribution within a growth ring. The bimodal frequency distributions of the tangential cell wall thickness and the radial lumen dimension provide an explanation for the observed bimodal frequency distribution of the cell water vapor permeability both in radial and in tangential directions. Contrary to measured macroscopic vapor permeability results, the tracheid geometry results in lower cell vapor permeability in radial than in tangential direction. This confirms that rays play an important role in the vapor permeability of wood, as they can be considered as pathways for vapor transport in radial direction. The dataset analyzed in this paper leads to a set of parameters characterizing the earlywood and latewood cell dimensions. Such characterization can be used, for example, for producing synthetic data for computational modeling studies.

Distribution of radiocesium and stable elements within a pine tree

Distributions of (137)Cs and stable elements in different parts of a pine tree collected in Chernobyl-contaminated area in Belarus were determined. Samples include annual tree rings of wood, branches and needles with different ages. The concentrations of (137)Cs and stable Cs in annual tree rings were the highest in cambium and decreased sharply towards inside. The youngest needles and branches contained higher (137)Cs and stable Cs than older ones. The concentration of (137)Cs being highest in growing parts suggests the highest radiation dose to the radiation-sensitive parts of tree. Distribution patterns of stable elements in pine tree differ among the elements. Distributions similar to those of Cs were observed for K and Rb, suggesting that alkaline metals tend to be translocated to young growing parts of pine tree. A similar distribution was also observed for phosphorus. Distributions of alkaline earth metals and several heavy metals were different from those of alkaline metals.

Growth, fire history, and browsing recorded in wood rings of shrubs in a mild temperate climate

Growth, fire history, and browsing recorded in wood rings of shrubs in a mild temperate climate

Growth, fire history, and browsing recorded in wood rings of shrubs in a mild temperate climate

Separate effects of abiotic and biotic factors on the structure and dynamics of ecological communities may be recorded in growth rings of woody plants. We used Ceanothus cuneatus rigidus and Arctostaphylos pumila to tease apart the roles of fire, rain, and herbivores on the histories and community structure of four areas in a coastal mediterranean-type climate in central California with mild winters and mild summers. Ring widths of both species were related to rainfall in two of the areas; heavy deer browsing on Ceanothus overwhelmed the climate signal in the others. Ceanothus germination was more closely related to heavy rainfall, especially during ENSO years, than to fire events. In a related greenhouse experiment that evaluated these observations, the same proportions of new Ceanothus seeds germinated after burning and after receiving regular water for several months, but germination of old seeds responded primarily to the fire treatment. In areas where heavy browsing by mammals reduces recruitment and growth of Ceanothus and increases mortality, the continuance of the Ceanothus population must rely heavily on germination from the persistent seed bank during unusually wet years or after occasional fires. Because Arctostaphylos can produce new stems from underground roots, individual plants may survive and produce seeds until another fire.

A statistical analysis of the impact of nematode attack symptomatology on the mechanical behaviour of Pinus pinaster Ait. wood

An appraisal was made about the impact of pinewood nematode (Bursaphelenchus xylophilus, Nickle) attack symptomatology on the mechanical behaviour of wood from Pinus Pinaster Ait. Two sets of 200 wood specimens were obtained for the study of both mechanical and other physical properties. The specimens, about half of which presented symptoms of nematode, were obtained from a set of 66 wood planks, cut from an equal number of trees, originating from the Setubal Peninsula (Portugal). Logistic analysis using symptomatology as a binary dependent variable showed adequacy of models containing compression tension to rupture and number of wood rings per unit radial length for the prediction of nematode attack. Analysis of variance revealed that the presence of the disease symptoms was correlated to static bending rupture, modulus of elasticity, work to maximum bending load, and axial compression rupture, causing their decrease at a significance level of 5%.

Seasonal dimorphism in wood anatomy of the Mediterranean Cistus incanus L. subsp. incanus

In Mediterranean-type ecosystems, seasonal dimorphism is an adaptive strategy aimed to save water by developing brachyblasts with xeromorphic summer leaves as opposed to dolichoblasts with more mesomorphic winter leaves. The aim of this study was to analyse the anatomical properties of 1-year-old twigs of Cistus incanus subsp. incanus, a seasonally dimorphic shrub, to highlight properties allowing its adaptation to the Mediterranean environment. A more specific purpose was to verify the occurrence of seasonal dimorphism in wood anatomy in order to understand: (a) whether and to what extent the traits of efficiency/safety of water transport are expressed in brachyblasts and dolichoblasts, and (b) the effects on the formation of growth ring boundaries in wood. Our overall analysis showed that anatomical features of branches in C. incanus are designed to: (a) protect from desiccation by developing thick cuticle and suberized epidermal and sub-epidermal layers; (b) defend the plant from predators by accumulating phenolics; and (c) regulate water transport through the development of specific wood anatomy, according to the season, thus optimising properties of efficiency/safety. Regarding the latter point, our results indicated that brachyblast wood is safer than dolichoblast wood insofar as it has narrower and more frequent vessels; measurement of other specific anatomical traits, such as vessel wall thickness, suggested that brachyblast wood has a higher resistance to implosion due to drought-induced embolism. Finally, peculiar anatomy of brachyblast and dolichoblast wood results in the formation of so-called false rings. Hence, wood rings in C. incanus should be considered to be “seasonal” rather than “annual”.

Jahrringe, Lawinen und eine zerstörte Alphütte | Tree rings, avalanches and a destroyed cottage

In winter 1999, several buildings and cottages have been destroyed by a large snow avalanche in and around the village of Evolene (Valais, Switzerland). The age of the cottages destroyed by the event was supposed to be considerable, but the individual buildings were not dated. It was therefore the goal of this study to assess the age of one of the cottages with dendrochronological methods. The investigation was based on a local reference chronology composed of 19 reference larch trees (Larix decidua Mill.) from the Evolene region. The reference chronology was built through optical and statistical analyses of the samples as well as crossdating methods. The chronology extends back to 1642, with a minimum sample depth of three trees from 1654 and five trees from 1725. Through the comparison of the reference chronology with a piece of wood from the destroyed cottage, it was possible to date the outermost ring of the construction wood to AD 1693. The age of the dated construction wood suggests that the flow path of the 1999 avalanche was unusual and that it affected a sector that has, most probably, not suffered from similar events since at least 300 years.

Genetic variation of wood quality traits and relationships with growth in Picea abies

Genetic parameters were estimated for wood density and spiral grain in two long-term field trials with families of Picea abies (L.) Karst., and for microfibril angle (MfA) and model-predicted wood stiffness (MOEest) at one of the sites. The trials were located at 600–720 m altitude in Norway and the progenies, which were a sample of 13 half-sib families from plus-trees in a breeding population, were 33 years old from seed when measured. Significant genetic variation (p<0.05) was found for all wood quality traits. The narrow-sense heritability was estimated to be 0.50 for density (across two sites), 0.38 for MfA, 0.29 for MOEest and 0.37 for spiral grain (across two sites). No significant genotype by environment interactions were found for density or spiral grain (p>0.05). Genetic relationships between ring width and wood quality traits were negative for density and MOEest, and positive for MfA. Site index and competition had major effects on wood density and predicted MOEest but not on MfA and spiral grain.