Log Height Research Articles

An investigation into the flexural properties of sawn timber and poles of South African grown Pinus maximinoi (H.E.Moore)

Pinus maximinoi is a species that can potentially be deployed commercially to provide structural timber and poles for the South African market. The objective of this study was to investigate the flexural properties of sawn timber and poles of P. maximinoi from young plantations of the Southern Cape. A total of 60 trees and 150 logs for the sawmill study were obtained from two research trials on the Longmore estate in the Humansdorp area (13.7 years old), and on the Kruisfontein estate close to Knysna (9.0 years old). Some 74 poles from the same compartments were removed and tested in bending. The P. maximinoi sawn timber had excellent bending properties, superior to sawn timber from other South African Pinus species, tested at similar radial positions in previous studies. Analysis of variation showed that site, log height and board radial position had a significant influence on the modulus of elasticity (MOE) of sawn timber. Multiple regression analysis showed that board MOE can be predicted using a model including tree taper, time-of-flight measured with Treesonic and wood density (model R 2 = 0.87). The P. maximinoi poles complied with the mean MOE national standard requirement SANS 457-2 of 9 000 MPa but not with the fifth percentile (bending strength) modulus of rupture (MOR) requirement of 34 MPa. This study and other research, however, showed that the national standard requirement for MOR of poles might be too high for current log resources in South Africa. The investigation into the bending and other properties of P. maximinoi sawn boards and poles showed extremely positive results. Based on this wood quality study of P. maximinoi, it is certainly a very promising species for deployment in the Southern Cape and potentially other regions in South Africa.

Discovery and Biology of Spathius verustus Chao (Hymenoptera: Braconidae), a Potential Biological Agent on Two Monochamus Vectors of the Pinewood Nematode

Pine wilt disease in Korea can be managed by reducing vector density through chemical application. To reduce the side effects from pesticides, effective natural enemies must be identified and used to reduce the vectors’ natural density. Sentinel logs were used to investigate a parasitoid wasp parasitic to Monochamus alternatus and Monochamus saltuarius, the vectors of Bursaphelenchus xylophilus, which causes this disease. During 2016–2017, the parasitoid wasps distributed in the Pinus densiflora and Pinus koraiensis forests were surveyed using sentinel logs at six different areas. An ectoparasitoid wasp Spathius verustus Chao of M. alternatus and M. saltuarius was identified. We showed for the first time that S. verustus was parasitic to M. alternatus in South Korea and to M. saltuarius worldwide. The parasitism rates were affected by region and session but not by the sentinel log height in the tree and the distances between the trap and forest edge locations. Studies also showed that S. verustus appeared to prefer M. alternatus to M. saltuarius as a host. This study unveiled the ecological details of S. verustus. Further research on various environmental factors such as regional differences, host density differences, and the degree of damage from the pine wilt disease is required to understand the effects of environmental or ecological factors on parasitism rates.

Saturated buffer design flow and performance in Illinois.

There are few peer-reviewed studies documenting saturated buffer annual nitrate (NO3 ) removal or that have assessed the federal practice standard design criteria. Drainage flow, NO3 , and dissolved reactive phosphorus (DRP) were monitored at three saturated buffers in Illinois, USA, for a combined 10 site-years. Nitrate loss reduction averaged 48 ± 19% with removals of 3.5-25.2kg NO3 -N ha-1 annually. Median DRP concentrations at all sampling locations were at the analytical detection limit of 0.01mg L-1 . The current design paradigm (i.e., USDA practice standard) prescribes there should be no flow bypassing the saturated buffer at flow rates that are ≤5% of the peak drainage system flow rate. The drainage coefficient-based and Manning's equation-based peak flow estimates were higher and lower, respectively, than the observed annual peaks in all years. This illustrated inherent uncertainty introduced early in the design process, which can be further compounded by dynamic in-buffer hydrology. The percentage of the observed peak flow rate at which bypass initiated ranged across an order of magnitude between sites (4.4-8.1% of peak flow rate at one site and 42-49% of peak at another) despite the buffers providing relatively similar NO3 removal. Bypass at one site (SB2) was related to the concept of "antecedent buffer capacity filled," which was defined as the 5-d average water depth in the middle control structure chamber expressed as a relative percentage of the bypass stop log height. This design flow analysis serves as a call to further evaluate predictive relationships and design models for edge-of-field practices.

Wood density and wood shrinkage in relation to initial spacing and tree growth in black spruce (Picea mariana)

This study has quantified basic wood density and various types of wood shrinkage in relation to initial spacing (or initial planting density) and tree growth based on a 48-year-old black spruce (Picea mariana) spacing trial in eastern Canada. A total of 139 sample trees were collected from four initial spacings (3086, 2500, 2066, 1372 trees/ha) for this study. Analyses of variance (ANOVA) show that initial spacing is the most important parameter affecting wood density significantly, followed by tree diameter at breast height (DBH) class. With increasing spacing, wood density, radial and volumetric shrinkage tend to decrease, whereas longitudinal shrinkage tends to increase gradually. The largest spacing has the lowest wood density, the smallest transverse shrinkage and the largest longitudinal shrinkage. Path analysis indicates that wood density is the most important parameter affecting transverse shrinkage, followed by the distance from the pith. Furthermore, much of the variation of the transverse shrinkage with wood density may be due to the initial spacing and tree DBH class. Path analysis also reveals that longitudinal shrinkage is mainly related to log height and tree DBH class. With increasing log height, longitudinal shrinkage tends to increase, and transverse shrinkage tends to decrease. With increasing DBH class, the trees tend to have an increasing longitudinal shrinkage and a decreasing transverse shrinkage. Overall, this study suggests that a large increase in the initial spacing (e.g., 1372 trees/ha) might lead to a significant reduction in both wood density and transverse shrinkage, and a significant increase in longitudinal shrinkage in black spruce.

Density Distribution in Wood of European Birch (Betula pendula Roth.)

The aim of the presented research is to perform a comprehensive analysis of wood density variability on the longitudinal and transverse cross-section of log trees at the age of 70 to 72 years of Betula pendula Roth. and the creation of density distribution maps. Furthermore, the determination proportion of juvenile and mature wood was done. Wood density was determined with a non-destructive method using an isotopic densimeter. It was found that the wood location, both in cross-section and longitudinal section of the trunk, had a statistically significant effect on the average density of birch wood. The average density of whole logs was significantly higher than the average density at the breast height. On the cross-section, the distribution of average densities determined at the breast height, as well as on ¼ of the log height, properly depicted the distribution of average densities on the cross-section determined for the whole logs. The geographical direction (north–south) did not have a statistically significant effect on the distribution of average densities on the cross-section of the tested birch logs.

Ensuring the Strength of Round Logs with a Longitudinal Hole Walling Wooden Houses

In the article the questions devoted to the study of strength and thermal insulation properties of round logs. To prevent shrinkage and surface cracks is proposed to be dried logs through the through longitudinal hole. The proposed method of determining geometric parameters of longitudinal openings for the drying of logs, provided that the strength of the logs for a given it loads in the design of the exterior walls of the typical wooden house. Study on stress-strain state round logs in the outer walls of a wooden frame with a longitudinal hole diameters. Determined that most dangerous when the loads are voltage along the contour of the holes. The dependences obtained for the appointment of the diameter and position of holes of the load acting on the beam showed that the holes can be different depending on the position in the log height of the structure. Justified based on the thermal resistance from geometric parameters of round logs.

Determination of the Geometric Parameters of Round Logs as Functional Materials for Wooden Housing Construction

The article is devoted to the study of strength and thermal insulation properties of logs OBrien. To prevent shrinkage and surface cracks it is proposed to dry logs through the through longitudinal hole. The proposed method is the method of determining geometric parameters of longitudinal openings for the drying of logs, provided that the strength of the logs for a given it load in the design of the exterior walls of the typical wooden house. The stress-strain state of round logs in the outer walls of a wooden frame with a longitudinal hole diameters was studied. It was found that the most dangerous for the considered loadings are the stresses along the contour of the holes. The dependences obtained for the appointment of the diameter and position of holes of the load acting on the beam showed that the holes can be different, depending on the position in the log height of the structure. It was justified, based on the thermal resistance from geometric parameters of round logs.

Effect of human-induced forest edges on the understory bird community in Hyrcanian forests in Iran: Implication for conservation and management

Understanding bird species responses to edge effect is critical for effective forest ecosystem management. We studied changes in diversity, density and abundance of bird communities and environmental variables along an edge-interior gradient in the Saadabad-Naharkhoran forested area located within the Hyrcanian forests in Iran. Bird species and environmental variables were recorded within a 25m radius of 81 sampling points. Distance from the edge had significant impact on the abundance of some species including Great Spotted Woodpecker, Nuthatch, Treecreeper and bark gleaning birds. Among diversity and evenness indices, Simpson diversity index, Shannon diversity index, and N1 and N2 indices showed significant differences. Bird species showed different density patterns in our study. Some species such as Great Tit, Nightingale, Carrion Crow and Black Bird responded positively, and Great Spotted Woodpecker, Nuthatch, Wren and Blue Tit responded negatively to forest edge conditions. Bird community analysis divided bird species into two main groups. The first group includes Pheasant, Nightingale, Jay and Blackbird which showed positive responses to edge effect and had a high correlation with variables such as ground cover, number of trees with dbh 12–20cm and temperature. The second group consisted of Treecreeper, Great Spotted Woodpecker, Green Woodpecker, and Nuthatch which showed a negative response to the edge effect and a positive correlation with snag and log dbh, snag and log height, the number of trees with dbh 100–300cm, canopy cover, life litter depth and dbh of the trees. Results obtained from this study can be important in conservation and management of bird communities in remnant Hyrcanian forests. Also, protected areas in some parts of Hyrcanian forests can be selected based on environmental variables with a positive correlation with edge-eluding species.

Modelling variation in wood density within and among trees in stands of New Zealand-grown radiata pine

Density is an important wood property due to its correlation with other wood properties such as stiffness and pulp yield, as well as being central to the accounting of carbon sequestration in forests. It is influenced by site, silviculture, and genetics, and models that predict the variation in wood density within and among trees are required by forest managers so that they can develop strategies to achieve certain wood density targets. The aim of the study presented here was to develop a wood density model for radiata pine (Pinus radiata D. Don) growing in New Zealand. The model was developed using an extensive historical dataset containing wood density values from increment cores and stem discs that were obtained from almost 10,000 trees at over 300 sites. The model consists of two sub-models: (1) a sub-model for predicting the radial variation in breast-height wood density and (2) a sub-model for predicting the distribution of density vertically within the stem. The radial variation in breast-height wood density was predicted as a function of either ring number or both ring number and ring width, with the latter model better accounting for the effects of stand spacing. Additional model components were also developed in order to convert from annual ring density values to a whole-disc density, predict log density from disc densities, and account for the variation in wood density among individual trees within in a stand. The model can be used to predict the density of discs or logs cut from any position within a tree and can utilise measured outerwood density values to predict the density by log height for a particular stand. It can be used in conjunction with outerwood density to predict wood density distributions by logs for stands of any specified geographic location and management regime and is designed to be able to incorporate genetic adjustments at a later stage. The analysis has confirmed and quantified much of the previous knowledge on the factors that affect the variation in wood density in radiata pine, particularly the influences of site factors and silviculture. It has also quantified the extent and patterns of variation in wood density within and among trees.

Body Weight and Relative Brain Size (Encephalization) in Eocene Archaeoceti (Cetacea)

Calibration of the Brownian diffusion model of Felsenstein indicates that phylogeny may have an influence on body length and other phenotypic measures in Cetacea for as many as 10,000 generations or about 180,000 years, which is negligible in the 35 million year history of extant Cetacea. Observations of phenotypic traits in cetacean species living today are independent of phylogeny and independent statistically. Four methods for estimating body weight in fossil cetaceans are compared: (1) median serial regression involving a set of multiple regressions of log body weight on log centrum length, width, and height for core vertebrae; (2) regression of log whole body weight on log body length for individuals; (3) regression of log whole body weight on log body length for species means; and (4) regression of log lean body weight on log body length for individuals. These yield body weight estimates for the Eocene archaeocete Dorudon atrox of 1126, 1118, 1132, and 847 kg, respectively, with consistency and applicability to partial skeletons favoring the first approach. The whole-body weight expected, Pe (in kg), for a given body length, Li (in cm), is given by log10 Pe = 2.784 • log10 Li − 4.429. Negative allometry of body weight and body length (slope 2.784 < 3.000) means that small cetaceans are shorter and more maneuverable than expected for their weight, while large cetaceans are longer and more efficient energetically than expected for their weight. Encephalization is necessarily quantified relative to a reference sample, most mammals are terrestrial, and terrestrial mammals provide a logical baseline. The encephalization residual for living terrestrial mammals as a class (ERTC), is the difference between observed log2 brain weight (Ei in g) and expected log2 brain weight (Ee in g), where the latter is estimated from body weight (Pi in g), as log2 Ee = 0.740 • log2 Pi − 4.004. ERTC is positive for brains that are larger than expected for a given body size, and negative for brains that are smaller than expected. Base-2 logarithms make the ERTC scale intuitive, in uniform units of halving or doubling. Encephalization quotients (EQ) are unsuitable for comparison because they are proportions on a non-uniform scale. Middle Eocene archaeocetes have ERTC values close to −2 (two halvings compared to expectation), while late Eocene archaeocetes have ERTC values close to −1 (one halving compared to expectation). ERTC is not known for fossil mysticetes, but living mysticetes have ERTC values averaging about −2. Oligocene-Recent odontocetes appear to have ERTC values averaging about +1 (one doubling compared to expectation) through their temporal range. Definitive interpretation of the evolution of encephalization in Cetacea will require better documentation for Oligocene–Recent mysticetes and odontocetes.

Post-harvest windthrow and recruitment of large woody debris in riparian buffers on Vancouver Island

Large woody debris (LWD) provides structural complexity to small streams. Riparian buffers are intended to provide long-term vegetation cover and supplies of LWD, but post-harvest windthrow often occurs. To evaluate the impacts of windthrow in riparian buffers and identify the components for a small stream LWD recruitment model, we sampled 26 streams in immature and older stands in wind-exposed areas of southwestern and northern Vancouver Island. These treed buffer strips had been exposed following clearcut harvest of adjacent timber on both sides 1–20 years previously. For stream sections 100 m long in each buffer, all logs greater than 7.5 cm diameter that spanned at least part of stream channel were measured. A total of 658 logs were recorded. Windthrown trees were comparable in characteristics to the trees that made up the buffer. The majority of logs derived from windthrown trees were oriented perpendicular to the stream channel and were suspended above the stream channel. Even 20 years after harvesting, two-thirds of the logs were still suspended above the stream. Logs in older buffers were more decayed, and the decay rate depended on tree species and initial diameter. Log height above stream was negatively correlated with log decay class and time since logging. Log length declined with time since harvest exposure and decay class. Sediment was exposed on upturned roots and within mineral soil pits. The volume of soil retained on upturned rootwads declined over time, but some soil remained even after 20 years. Very little of this exposed sediment was close enough to the creek to result in sediment delivery.

Windthrow and recruitment of large woody debris in riparian stands

To document the impacts of windthrow in riparian leave strips and identify the components needed for small stream large woody debris (LWD) recruitment modeling, we monitored nine small streams at a temperate rainforest site in coastal British Columbia. This study was a component of a larger integrated study of forest management impacts on small streams. A series of small clearcuts were harvested in 1998 in a 70-year-old second growth stand that had regenerated naturally following logging and wildfire. Three cutblocks each were assigned to 10 m and 30 m buffer width treatments and three areas were assigned as unharvested controls. Seven years after the 1998 logging, all logs greater than 10 cm diameter that spanned at least part of stream channel width were measured. A total of 179 logs were recorded. Post-harvest windthrow was higher in the 10 m buffer treatment, while competition-related standing tree mortality was higher in the controls. The major windthrow events had occurred in the first and second years after logging of adjacent stands. There was no significant difference in the number of spanning and in-stream logs in the 10 m, 30 m buffer and control treatments. More than 90% of the LWD was in the 10–30 cm diameter classes. The majority of logs were oriented perpendicular to the stream channel. At the time of measurement, the majority of these trees were still suspended above the stream channel, indicating that the recruitment of logs into the stream channel is a long-term process. Time to recruitment into the channel is dependent on log and valley geometry, log size, species, and log condition prior to toppling. Log height above stream was negatively correlated with log decay class and valley width. Log length was negatively correlated with state of decay, and many windthrown logs were in an advanced state of decay before they entered the stream.

Aphid aerial density profiles are consistent with turbulent advection amplifying flight behaviours: abandoning the epithet ‘passive’

Seminal field studies led by C. G. Johnson in the 1940s and 1950s showed that aphid aerial density diminishes with height above the ground such that the linear regression coefficient, b, of log density on log height provides a single-parameter characterization of the vertical density profile. This coefficient decreases with increasing atmospheric stability, ranging from -0.27 for a fully convective boundary layer to -2.01 for a stable boundary layer. We combined a well-established Lagrangian stochastic model of atmospheric dispersal with simple models of aphid behaviour in order to account for the range of aerial density profiles. We show that these density distributions are consistent with the aphids producing just enough lift to become neutrally buoyant when they are in updraughts and ceasing to produce lift when they are in downdraughts. This active flight behaviour in a weak flier is thus distinctly different from the aerial dispersal of seeds and wingless arthropods, which is passive once these organisms have launched into the air. The novel findings from the model indicate that the epithet 'passive' often applied to the windborne migration of small winged insects is misleading and should be abandoned. The implications for the distances traversed by migrating aphids under various boundary-layer conditions are outlined.

Predicting decay and round-wood end use volume in trembling aspen (Populus tremuloides Michx.)

• In Quebec (Canada), predicting net merchantable volume of standing trees is essential to adjust stumpage fees. Furthermore, round-wood end use is important in the provincial forest management context because it is used to split the allowable annual cut among the different mill types. • A method relying on linear, binomial and cumulative logit regressions is proposed to predict both decay volume and round-wood end use volume. Tree age, height and quality, as well as ecological region, stand origin and presence of Phellinus tremulae (Bond.) Bond. & Boriss. and Ceratocystis fimbriata (Ellis & Halst.) fungi are the main factors that contribute to the presence and the proportion of decayed merchantable volume. Once the net merchantable volume is estimated, its division into round-wood end use is estimated through a series of steps involving the presence of Phellinus tremulae, saw log height, stem quality and size as explanatory variables. The first step is a multinomial regression which predicts the number of end uses (pulp wood, low-grade saw logs, saw logs, low-grade veneer, and veneer) that are present in the stem. A series of logistic regressions then determines the presence of each end use, with linear regressions predicting the round-wood volume of each end use.

Entropic repulsion for a class of Gaussian interface models in high dimensions

Consider the centred Gaussian field on the lattice Z d , d large enough, with covariances given by the inverse of ∑ j = k K q j ( − Δ ) j , where Δ is the discrete Laplacian and q j ∈ R , k ≤ j ≤ K , the q j satisfying certain additional conditions. We extend a previously known result to show that the probability that all spins are nonnegative on a box of side-length N has an exponential decay at a rate of order N d − 2 k log N . The constant is given in terms of a higher-order capacity of the unit cube, analogously to the known case of the lattice free field. This result then allows us to show that, if we condition the field to stay positive in the N -box, the local sample mean of the field is pushed to a height of order log N .

Prediction of total body water in infants and children

Background: In paediatric clinical practice treatment is often adjusted in relation to body size, for example the calculation of pharmacological and dialysis dosages. In addition to use of body weight,...

Weight‐height relationships and body mass index: Some observations from the diverse populations collaboration

Body mass index (BMI, weight (kg)/height (m)(2)) is the most widely used weight-height index worldwide. This universal use of BMI assumes that the rationale for its use is universally applicable. We examine two possible rationales for using BMI as a universal measure. The first rationale is that BMI is strongly correlated with weight, but is independent of height. The second rationale is that BMI correctly captures the relationship between weight and height, which implies that the slope of log weight regressed on log height is 2. We examined the weight-height relationship in 25 diverse population samples of men and women from the US, Europe, and Asia. The analysis included 72 subgroups with a total of 385,232 adults aged 25 years and older. Although BMI was highly correlated with weight in all studies, a significant, negative correlation between BMI and height was found in 31 out of 40 subgroups of men (r=-0.004 to -0.133) and 32 of 32 groups of women (r=-0.016 to -0.205). When log weight was regressed on log height, the 95% confidence intervals (CI) of the slopes did not include 2 in 25 out of 40 male subgroups. The summary estimate of the slopes across studies of men was 1.92 (95% CI, 1.87-1.97). For women, slopes were lower than 2 in 28 of 32 subgroups with a summary estimate of 1.45 (95% CI, 1.39-1.51). In most of the populations, BMI is not independent of height; weight does not universally vary with the square of height; and the relationship between weight and height differs significantly between males and females. The use of a single BMI standard for both men and women cannot be justified on the basis of weight-height relationships.

SHORT-TERM AND LONG-TERM EFFECTS OF AIR POLLUTION ON LUNG FUNCTION

ISEE-73 Introduction: We previously reported that annual mean particulate air pollution concentrations were associated with lower lung function in a cross-sectional study of schoolchildren in 24 cities across the United States and Canada. In this analysis we estimated the effects of daily pollution on pulmonary function testing to assess the short-term effects in a sample of more than 10,000 schoolchildren in 22 of the original 24 study sites. Methods: We used a mixed linear model with random city effects to regress the logarithms of pulmonary function parameters (FVC, FEV1.0, FEF25-75%, and PEFR) against sex, age, log height and weight, an interaction of sex and log height, indicators for environmental tobacco smoke exposure and asthma, and air pollution measurements. Long-term exposure was estimated as the annual mean concentrations for the 12 months preceding the pulmonary function tests and short-term exposure as the 6-day moving average of the daily deviations from the long-term annual means. Results: Increased long-term particulate and ozone concentrations were associated with decreased lung function in the range of –1.5% to –3.5%. Increased short-term pollution in PM2.1 and PM10 was associated with decreased FVC, FEV1.0, and FEF25-75%. A 5.8 μg/m3 increase in the 6-day moving average of PM2.1 was associated with a 0.34% lower FVC (95% CI: −0.65, −0.04%), with a 0.35% lower FEV1.0 (−0.68%, −0.02%), and a 0.47% lower FEF25-75% (−1.29, 0.36). Short-term effects of ozone on FVC, FEV1.0, and FEF25-75%, were consistently higher for asthmatic children compared to non-asthmatics, and short-term effects of particles and ozone on FVC and FEV1.0 were consistently higher for obese children compared to non-obese children. There was no indication of effect modification by gender or environmental tobacco smoke exposure. Inclusion of the short-term air pollution effects consistently led to slightly stronger negative effects of the long-term effects. Discussion: This study showed that in addition to the impact of long-term exposure the pulmonary function performance is influenced by air pollution concentrations in the days before the test. These acute effects are smaller than the chronic effects and the effects on lung function for acute and chronic air pollution exposure are independent and additive.

Effect of Competition on Plant Allometry and Defense

A series of experiments was conducted to examine the effects of competition on allometry and defense using tomato plants (Lycopersicon esculentum). No mortality occurred over the 4-wk test period, even with a plant density of 30 plants per 10-cm2. However, allometric patterns for log canopy diameter vs. log height indicated that competition occurred as early as 8 d after transplant and for pots with as few as two young plants (density of about 2 plants per 10-cm2). There was a change towards less root mass for greater height as competition increased. Leaf concentration of the allelochemicals chlorogenic acid, rutin and tomatine increased with decreasing competition, with the sum of these exhibiting a sigmoid-like pattern for allelochemical concentration. But competition did not affect leaf proteinase inhibitor activity, or petiole glandular trichomes or total trichomes. While the results are compatible with the growth-differentiation balance (GDB) hypothesis, they also indicate some of the difficulties that will be encountered in testing the GDB hypothesis rigorously.

Entropic repulsion for a Gaussian lattice field with certain finite range interaction

Consider the centered Gaussian field on Zd, d⩾2l+1, with covariance matrix given by (∑j=lKqj(−Δ)j)−1 where Δ is the discrete Laplacian on Zd, 1⩽l⩽K and qj∈R,l⩽j⩽K are constants satisfying ∑j=lKqjrj&amp;gt;0 for r∈(0,2] and a certain additional condition. We show the probability that all spins are positive in a box of volume Nd decays exponentially at a rate of order Nd−2l log N and under this hard-wall condition, the local sample mean of the field is repelled to a height of order log N. This extends the previously known result for the case that the covariance is given by the Green function of simple random walk on Zd (i.e., K=l=1,q1=1).