Stem eccentricity in coastal western hemlock

1981 ◽  
Vol 11 (3) ◽  
pp. 715-718 ◽  
Author(s):  
Robert M. Kellogg ◽  
Francis J. Barber
Keyword(s):  
Major Axis ◽  
Western Hemlock ◽  
Eccentricity Ratio ◽  
Angular Rotation ◽  
Minimum Diameter ◽  
Breast Height ◽  
Second Growth ◽  
The Difference ◽  
Average Eccentricity ◽  
Practical Field

Stem eccentricity in second-growth western hemlock (Tsugaheterophylla (Raf.) Sarg.) from southern coastal British Columbia appears to be the rule rather than the exception. Although the difference was small, the average eccentricity ratios (ratios of minimum diameter inside bark (DIB) to maximum DIB) for two Lower Mainland sites were significantly larger than those of two Vancouver Island sites. The average eccentricity ratio of all 87 trees studied was 0.929, with a standard deviation of 0.0231. The angular rotation of the major axis of the stem cross section varied greatly, and was positively related to the average stem eccentricity ratio within 5-m log lengths for each stem. Average eccentricity of the whole stem was relatively independent of diameter at breast height (DBH), age, stem height, and eccentricity at breast height. It does not appear that a practical field technique could be devised for the rapid estimation of average stem eccentricity in western hemlock.

Anisotropy Gas Reservoir Drainage Radius and Quantitative Well Interference Study

2013 ◽  
Vol 275-277 ◽  
pp. 1285-1291 ◽  
Author(s):  
Zheng Long Gao ◽  
Hong Fu Fan ◽  
Zhi Bin Gao
Keyword(s):  
Production Rate ◽  
Major Axis ◽  
Productivity Analysis ◽  
Analysis Method ◽  
Equivalent Radius ◽  
Average Value ◽  
Drainage Radius ◽  
Well Spacing ◽  
Cumulative Production ◽  
The Difference

Unstable productivity analysis method was used to obtain the equivalent radius of 77 wells and the result shows that the equivalent radius ranges from 30 to 970m with an average value of 230m in McKittrick Hills. The difference range of the radius is mainly caused by varying formation properties, gas saturation, production time, etc. Permeability anisotropy changes the drainage from round to ellipse. The major axis and the minor axis of the ellipse are determined by the ratio of major and minor permeability. Current pressure distribution was obtained and was found to be consistent with the modified drainage results, which demonstrates that the unstable productivity analysis method is applicable in the study of gas well drainage radius. An interference well and an observation well’s model was constructed to study well interference quantitatively. When the well spacing is larger than 750m, the productivity will be reduced by 20%. The production rate of interference well is more sensitive to the cumulative production of observation well, when the production rate of interference well is below 16.8×104m3/d.

scholarly journals Static and dynamic operating characteristics of a pericardial balloon

2001 ◽  
Vol 90 (4) ◽  
pp. 1481-1488 ◽  
Author(s):  
Douglas R. Hamilton ◽  
Gwyneth Devries ◽  
John V. Tyberg
Keyword(s):  
Frequency Response ◽  
Diastolic Pressure ◽  
Ventricular Volume ◽  
Left Ventricular ◽  
Operating Characteristics ◽  
Minimum Diameter ◽  
Before And After ◽  
Unity Gain ◽  
Dynamic Operating ◽  
The Difference

Previously, we developed a balloon transducer to measure the constraint of the pericardium (i.e., pericardial pressure) on the surface of the heart. It was validated physiologically in that it was shown to measure a pressure equal to the difference between the left ventricular end-diastolic pressure measured before and after pericardiectomy at the same left ventricular volume. To define its static operating characteristics, we loaded the balloon nonuniformly with weights that covered fractions of the balloon surface and found that the balloon accurately recorded the average stress if the stress was applied over at least 23% of its surface. To test its performance when curved, we placed it in large and small cylinders (minimum diameter 31 mm) and found that the balloon accurately recorded the stress. To define its dynamic operating characteristics, we applied sinusoidal stresses and found that its frequency response was limited only by that of the connecting catheter. When better dynamic response is required, we introduce a micromanometer-tipped catheter to obtain a unity-gain frequency response that is flat to 200 Hz.

Availability of N and P in the forest floors of adjacent stands of western red cedar–western hemlock and western hemlock–amabilis fir on northern Vancouver Island

1993 ◽  
Vol 23 (4) ◽  
pp. 605-610 ◽  
Author(s):  
C. E. Prescott ◽  
M.A. McDonald ◽  
G.F. Weetman
Keyword(s):  
Forest Floor ◽  
Forest Type ◽  
Western Hemlock ◽  
Red Cedar ◽  
Floor Layer ◽  
Second Growth ◽  
Extractable P ◽  
Western Red Cedar ◽  
Forest Floors ◽  
Floor Material

Availability of N and P was compared in the forest floors of old-growth forests of western red cedar (Thujaplicata Donn)and western hemlock (Tsugaheterophylla (Raf.) Sarg.) (CH forests), and second-growth forests of western hemlock and amabilis fir (Abiesamabilis (Dougl.) Forbes) (HA forests) of windthrow origin. Five samples of each forest floor layer (litter, fermentation (woody and nonwoody), and humus (woody and nonwoody)) were collected from three forests of each type (CH and HA). All layers of CH forest floors had smaller concentrations of total and extractable N and mineralized less N during 40-day aerobic incubations in the laboratory. Total and extractable P was lower in the litter layer of CH forest floors. Seedlings of western red cedar, Sitka spruce (Piceasitchensis (Bong.) Carr.), western hemlock, and amabilis fir grown from seed in forest floor material from CH forests grew more slowly and took up less N and P than did seedlings grown in HA forest floor material. The low supply of N and P in CH forest floors may contribute to the nutrient supply problems encountered by regenerating trees on cutovers of this forest type.

Granule Morphology of Supplementary Cementitious Materials under Different Cooling Conditions

2016 ◽  
Vol 723 ◽  
pp. 694-699
Author(s):  
Zai Bo Li ◽  
Xu Guang Zhao ◽  
San Yin Zhao ◽  
Tu Sheng He
Keyword(s):  
Building Materials ◽  
Major Axis ◽  
Cementitious Materials ◽  
Basic Oxygen Furnace ◽  
Supplementary Cementitious Materials ◽  
Basic Oxygen ◽  
Means Of Measurement ◽  
Granule Morphology ◽  
The Difference ◽  
Basic Oxygen Furnace Slag

Basic oxygen furnace slag (BOFS) , a mass supplementary cementitious materials, can be used as an active additive in building materials. The work present the result of granule morphology of two kinds of BOFS powder, cooled by water quenching (BOFS-W) and air splashing method(BOFS-A). Micrographs of two kinds of BOFS powder were observed with a scan electron microscope (SEM), then, length of major axis and minor axis of two-dimension projective outline of every granule in these SEM micrographs was measured manually and their ratio (RLB) was used to represent the granule sphericity. Each BOFS powder was divided into 6 parts with different granularity range. By means of measurement and statistical analysis, the average RLB value of granules with different granularity grade was obtained and the relation between size and sphericity of granule was explored. Result showed that BOFS-W is superior to BOFS-A in sphericity of granule. According to different granularity grade, statistical average values of RLB of BOFS-W and BOFS-A range 1.422-1.496 and 1.490-1.647, respectively. The difference of BOFS-W and BOFS-A on granule sphericity mainly is reflected in coarse granule.

Physical properties of earlywood and latewood of Pinus radiata D. Don: Anisotropic shrinkage, equilibrium moisture content and fibre saturation point

Holzforschung ◽  
2005 ◽  
Vol 59 (6) ◽  
pp. 654-661 ◽  
Author(s):  
Shusheng Pang ◽  
Alfred Herritsch
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Pinus Radiata ◽  
Growth Ring ◽  
Fibre Saturation Point ◽  
Longitudinal Shrinkage ◽  
Saturation Point ◽  
Breast Height ◽  
Second Growth ◽  
Tangential Shrinkage

Abstract Anisotropic shrinkage (tangential and longitudinal), equilibrium moisture content (EMC) and fibre saturation point (FSP) were measured for separated earlywood (EW) and latewood (LW) of a 0.75-m-long log of 20-year old Pinus radiata that was cut at breast height from a selected tree in the forest of Central North Island, New Zealand. The experimental results have shown that at 12% moisture content (MC), tangential shrinkage was 3.23% for EW and 3.90% for LW, with an overall average of 3.56%. Longitudinal shrinkage was 0.23% for EW and 0.21% for LW with an overall average of 0.22%. Shrinkage for the oven dry (OD) state showed similar trends to those at 12% MC in terms of the differences between EW and LW. The tangential and longitudinal shrinkage varied significantly along the radius from pith to bark. The EW tangential shrinkage increased from pith to the seventh growth ring and then remained relatively constant until the last ring adjacent to the bark. The LW tangential shrinkage also increased from the pith outwards until the seventh growth ring, but beyond that was more variable than the EW shrinkage. Both EW and LW showed similar longitudinal shrinkage, with the highest values in the second growth ring, from which the shrinkage decreased exponentially towards the bark. LW had a slightly higher EMC than EW at a relative humidity (RH) below 80%, but the trend was reversed for RH above 80%. The EMC differences between EW and LW were less than 0.6%. The overall average FSP for Pinus radiata was 29.1%, with actual values varying from 25% to 32.8%. The earlywood FSP (28.9%) was slightly lower than that of the latewood (29.4%).

Growth intercept models for species without distinct annual branch whorls: western hemlock

1996 ◽  
Vol 26 (8) ◽  
pp. 1407-1415 ◽  
Author(s):  
Gordon D. Nigh
Keyword(s):  
Site Index ◽  
Fixed Number ◽  
Western Hemlock ◽  
Breast Height ◽  
Growth Intercept

A growth intercept model is presented that is designed to estimate site index for juvenile stands of species without distinct annual branch whorls. It is called a variable growth intercept model and is demonstrated on western hemlock (Tsugaheterophylla (Raf.) Sarg.). The growth intercept is calculated from all the growth above breast height (hence the name variable), not just a fixed number of years' growth above breast height as is traditionally done. This technique gives more flexibility in using growth intercepts to estimate site index. It can also lead to more accurate estimates of site index because it incorporates more growth information.

Wood density of western hemlock: effect of ring width

1994 ◽  
Vol 24 (3) ◽  
pp. 638-641 ◽  
Author(s):  
Jeffrey D. DeBell ◽  
John C. Tappeiner II ◽  
Robert L. Krahmer
Keyword(s):  
Growth Rate ◽  
Wood Density ◽  
Growth Rates ◽  
Ring Width ◽  
Western Hemlock ◽  
X Ray ◽  
Breast Height ◽  
Latewood Density ◽  
Earlywood Width ◽  
Average Wood

Wood density of western hemlock (Tsugaheterophylla (Raf.) Sarg.) was determined by X-ray densitometry of strips from breast-height samples consisting of rings 20–24 from the pith. Ring parameters were averaged over the 5 years for each strip. Wood density was negatively correlated with radial growth rate. Average wood density dropped from 0.47 to 0.37 g/cm3 as average ring width increased from 2 to 8 mm. Wood density decreased at higher growth rates primarily because earlywood width increased while latewood width remained the same; as a result, percentage of latewood decreased. Earlywood density decreased slightly at higher growth rates, but latewood density was not significantly related to growth rate.

Operational biomass recovery of small trees: equations for six central Ontario tree species

2015 ◽  
Vol 45 (3) ◽  
pp. 372-377 ◽  
Author(s):  
Matt Thiel ◽  
Nathan Basiliko ◽  
John Caspersen ◽  
Jeff Fera ◽  
Trevor Jones
Keyword(s):  
Pinus Strobus ◽  
Size Class ◽  
Forest Types ◽  
White Pine ◽  
Breast Height ◽  
Biomass Equations ◽  
Bioenergy Feedstocks ◽  
Biomass Recovery ◽  
The Difference ◽  
High Degree

Accurate estimates of the amount of biomass that can be recovered at the roadside are needed to make informed decisions about whether to implement an increased utilization harvesting system to supply additional bioenergy feedstocks. Current estimates of recovery are based on total aboveground biomass equations that do not always account for the volume lost to the unharvested stumps or to tops and branches broken during forestry operations. The study took place in a white pine (Pinus strobus L.) mixedwood forest at the Petawawa Research Forest in central Ontario. Equations to describe recoverable biomass were developed from 371 cut and skidded trees, which ranged from 3 to 24 cm in diameter at breast height, across six species. For each species and diameter size class, we evaluated the difference between estimates produced by locally developed equations and those from published equations produced for other locations and forest types. Our recovered biomass estimates were generally higher than the Canadian national averages but within the observed range of published values from across North America. We report that small trees are recovered nearly in their entirety, with little breakage and loss during operations. The high degree of variability among estimates produced by the various equations poses one of the biggest challenges in accurately estimating roadside biomass in an operational setting.

scholarly journals A system for estimating height and site index of western hemlock in the interior of British Columbia

1998 ◽  
Vol 74 (4) ◽  
pp. 588-596 ◽  
Author(s):  
Gordon D. Nigh
Keyword(s):  
British Columbia ◽  
Site Index ◽  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Index Model ◽  
Breast Height ◽  
Age Model ◽  
Site Index Model ◽  
Growth Intercept ◽  
Height Model

The focus of recent site productivity research in British Columbia has been to develop height-breast height age, growth intercept, and ecosystem-site index models. These models, together with a years-to-breast-height model, form a system for estimating site index and height. This system is described for western hemlock (Tsuga heterophylla (Raf.) Sarg.) in the interior of British Columbia. Forty-four western hemlock stem analysis plots were used in the construction of this system. As there are three models for estimating site index, the appropriate model for a given stand depends largely on the stand condition and the precision of the models. A graph of model precision against breast height age gives some assistance in deciding which model should be used to estimate site index. Key words: western hemlock, site index, height-age model, growth intercept model, years-to-breast-height model, ecosystem-site index model, model precision

scholarly journals Resource Selection by Porcupines: Winter Den Site Location and Forage Tree Choices

2001 ◽  
Vol 16 (2) ◽  
pp. 53-57 ◽  
Author(s):  
Todd N. Zimmerling ◽  
Chad D. Croft
Keyword(s):  
Resource Selection ◽  
Sitka Spruce ◽  
Size Class ◽  
Western Hemlock ◽  
Site Location ◽  
Tree Species Composition ◽  
Erethizon Dorsatum ◽  
Size Classes ◽  
Second Growth ◽  
Conifer Tree

Abstract We examined the importance of tree species composition and tree size-class distribution in determining the selection of winter den sites and forage trees by porcupines (Erethizon dorsatum). Porcupines selected winter den sites with a higher composition of sitka spruce, in all diameter size classes. However, statistically significant selection was found only for the 15.0–19.9 cm dbh size classes of sitka spruce. Porcupines displayed a statistically significant avoidance of 5.0–9.9 cm dbh and 10.0–14.9 cm dbh western hemlock trees when selecting winter den sites. When foraging around the den sites, porcupines showed a statistical avoidance of amabilis fir in all size classes and selected western hemlock, except the smallest size class (5.0–9.9 cm dbh). The results of this study indicate that porcupines do not choose winter den site locations based on the availability of preferred forage resources. Porcupines appear to choose den sites based on within-stand, patch variation in the proportion of sitka spruce and small dbh western hemlock. Forage trees are then selected, nonrandomly from specific resource categories around the den site. Porcupines in this study were found to feed on a mean of 0.54 new forage trees/day. Regression analysis revealed a positive linear relationship between new forage trees used/day and porcupine midwinter weight (y = 0.15x–0.54; r2 = 0.73). The results indicate that larger porcupines may produce a larger proportion of observed conifer tree feeding damage in second growth stands, as compared to smaller porcupines. West. J. Appl. For. 16(2):53–57.

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