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.

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

Growth Intercept Methods for Predicting Site Index in Red Pine Plantations in the Allegheny Plateau of Ohio

1990 ◽  
Vol 7 (1) ◽  
pp. 27-30 ◽  
Author(s):  
James H. Brown ◽  
Charles A. Duncan
Keyword(s):  
Site Index ◽  
Height Growth ◽  
Red Pine ◽  
Site Quality ◽  
Soil Horizon ◽  
Old Field ◽  
Annual Increment ◽  
Breast Height ◽  
Allegheny Plateau ◽  
Growth Intercept

Abstract Growth intercept (GI) techniques were evaluated for estimating site quality in red pine stands planted on old-field sites in the unglaciated Western and Central Allegheny Plateau regions of Ohio. Correlations between height growth of trees below breast height (BH) and height growth above BH were not statistically significant. Site index estimates were made using age at BH and height from BH to the growing tip. Three-year and 5-year growth beginning three internodes above the BH annual increment and 10-year growth beginning one internode above BH were more significantly correlated with height than were intercepts beginning at BH. In equations developed for predicting site index, 3-, 5-, and 10-year intercepts in combination with age accounted for 64 to 80% of the variation in tree heights. Combining thickness of the A soil horizon with GI and age statistically increased the variation accounted for in the 3- and 5-year GI equations; however, for field use, the improvement in accuracy was not sufficient to justify making the additional soil measurement. North. J. Appl. For. 7(1):27-30, March 1990.

Estimating Site Quality of Young Red Pine Plantations by Growth Intercept Methods

1988 ◽  
Vol 5 (2) ◽  
pp. 91-93 ◽  
Author(s):  
Timothy R. Bottenfield ◽  
David D. Reed
Keyword(s):  
Analysis Data ◽  
Site Index ◽  
Height Growth ◽  
Red Pine ◽  
Pine Plantations ◽  
Site Quality ◽  
Stem Analysis ◽  
Breast Height ◽  
Growth Intercept

Abstract Five growth intercept measurements were correlated with site index of red pine plantations in the northern Lakes States. The growth intercept variables were obtained by direct field measurement or indirectly through interpolation of stem analysis data. Growth intercepts represented both time (age in years) and distance (height in feet) measurements. Growth intercepts representing time and the age at breast height are not recommended for use in young red pine plantations. The amount of height growth in the first five annual whorls above 5 and 8 ft were good predictors of site index. North. J. Appl. For. 5:91-93, June 1988.

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.

A Multipoint Felled-Tree Validation of Height–Age Modeled Growth Rates

2020 ◽  
Vol 66 (3) ◽  
pp. 275-283 ◽  
Author(s):  
Halli Hemingway ◽  
Mark Kimsey
Keyword(s):  
Growth Rates ◽  
Rocky Mountain ◽  
Site Index ◽  
Douglas Fir ◽  
Alternative Methods ◽  
Forest Site ◽  
Site Productivity ◽  
Site Factors ◽  
Forest Management Planning ◽  
Breast Height

Abstract Accurate measures of forest site productivity are essential for forest-management planning. The most common measure of site productivity is breast height–age site index (BHASI)—the expected height at a reference age. Error from including early growth in productivity estimates and limited applicability of any one BHASI model warrant development of alternative methods. Exploring alternatives may only be necessary if regional BHASI models are not accurately predicting growth rates. We compared modeled height growth rates for Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca) to felled-tree measurements to evaluate relative performance of a regional BHASI model. An orthogonal sampling design ensured samples were collected across a range of site factors known to influence Douglas-fir growth rates. Growth rates for each 10 m section were calculated and compared to BHASI modeled growth rates. The regional BHASI model underpredicted growth rates from breast height to 30 m. Observed growth rates from 10 to 30 m accounted for the majority of underprediction relative to BHASI modeled growth rates. An alternative multipoint method of defining site productivity is described. More research comparing BHASI and alternative methods is needed, given the growth rate error associated with one-point site productivity assessment.

scholarly journals Early Height Growth and Site Index of Lodgepole Pine Under Wet and Dry Soil Moisture Regimes in British Columbia

1997 ◽  
Vol 12 (1) ◽  
pp. 5-8
Author(s):  
Gordon D. Nigh
Keyword(s):  
Soil Moisture ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Site Index ◽  
Height Growth ◽  
Moisture Regimes ◽  
Indicator Variables ◽  
Soil Moisture Availability ◽  
A Site ◽  
Growth Intercept

Abstract The objective of this study was to determine whether the relationship between site index and early height growth of lodgepole pine (Pinus contorta var. latifolia) is the same on wet and dry sites. If the height growth/site index relationship is the same for different site types, then only one growth intercept model is required to estimate site index. Indicator variables in nonlinear regression were used to incorporate soil moisture availability into a growth intercept model. One set of parameters in a site index/early height growth model was adequate for both wet and dry sites. This result was supported graphically. Therefore, only one growth intercept model is necessary for the sites examined in this study. West. J. Appl. For. 12(1):5-8.

Site Index Curves for Norway Spruce in Southern Ontario1

1989 ◽  
Vol 6 (1) ◽  
pp. 23-26 ◽  
Author(s):  
Andrew M. Gordon ◽  
Peter A. Williams ◽  
Edward P. Taylor
Keyword(s):  
Norway Spruce ◽  
Soil Texture ◽  
Sandy Soils ◽  
Site Index ◽  
Height Growth ◽  
Stem Analysis ◽  
Mean Values ◽  
Breast Height ◽  
Drainage Class ◽  
The Mean

Abstract Four dominant or codominant Norway spruce trees from each of 55 sites were destructively sampled and the annual height growth determined by stem analysis. The sampled sites were stratified by soil textural class (coarse, medium, and fine) and depth to distinct mottling (0-16, 16-40, and 40 in.). Two sets of an-amorphic site index curves were constructed using a total age of 30 years (SI30), and breast height age of 25 years (SIBH25) as base ages. The mean SI30 from Ontario (53 ft) was found to be 17.8% higher than the mean values published from Vermont (45 ft) and currently used in Ontario. SIBH25 values had a range of 34.6 to 74.8 ft with a mean of 55.3 ft. Analysis of variance showed significant differences in SIBH25 due to soil texture and drainage class, and in years to breast height (BH) due to drainage class. SIBH25 was highest on sites with loamy soils and distinct mottling at 16-40 in. It took an average of 6.5 years for seedlings to reach BH with a range of 3 to 12 years. Years to BH was lowest on sites with sandy soils and those with distinct mottling below 40 in. North. J. Appl. For. 6(1):23-26, March 1989.

scholarly journals Growth Intercept Methods for Predicting Site Index in White Pine Plantations in the Glaciated Areas of Ohio

2006 ◽  
Vol 23 (3) ◽  
pp. 176-183 ◽  
Author(s):  
James H. Brown
Keyword(s):  
Site Index ◽  
Growth Increment ◽  
Annual Growth ◽  
Site Quality ◽  
Soil Horizon ◽  
Regression Equations ◽  
White Pine ◽  
Annual Increment ◽  
Growth Intercept ◽  
Annual Growth Increment

Abstract Growth intercept (GI) techniques were evaluated for estimating site quality in white pine stands planted on old-field sites in the Wisconsin-aged glaciated areas of northern and western Ohio. Correlations between growth of trees below the breast high (bh) annual growth increment andheight growth from bh and above were not statistically significant. Site index estimates were made using age at bh and height from the bh annual growth increment to the growing tip. Three-year and 5-year growth beginning 3 years above the bh annual increment and 10-year growth beginning oneinternode above bh were significantly more correlated with height than were intercepts beginning at bh. In multiple regression equations developed for predicting site index, 3-, 5- and 10-year intercepts, along with age at bh, accounted for 76, 77, and 80%, respectively, of the variationin tree heights and 35-year site indices varied from 60 to 83 ft. Combining clay content of the B2 soil horizon with GI and age increased the variation accounted for by 3-, 5-, and 10-year GI equations to 79, 78, and 81%, respectively, and the improvement in site index estimatesover those using GIs alone was not more than ±2 ft within any given GI measurement.

STUDIES IN FOREST PATHOLOGY: XII. DECAY OF WESTERN HEMLOCK IN THE UPPER COLUMBIA REGION, BRITISH COLUMBIA

1954 ◽  
Vol 32 (1) ◽  
pp. 145-171 ◽  
Author(s):  
R. E. Foster ◽  
H. M. Craig ◽  
G. W. Wallis
Keyword(s):  
Site Index ◽  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Site Quality ◽  
Advanced Stage ◽  
Multiple Correlation ◽  
Relative Percentage ◽  
Total Incidence ◽  
Average Defect ◽  
Mature Stands

An investigation of western hemlock (Tsuga heterophylla (Raf.) Sarg.) in the Upper Columbia region has shown that decay losses are excessive, amounting to 52 and 74% in terms of cubic and board foot computations respectively. The logs of 833 hemlock on 36 sample plots located in mature timber were analyzed in detail. Twenty-six decay-producing fungi have been isolated. Sixty-two per cent of the total decay was attributed to Echinodontium tinctorium Ell. & Ever. and 25% to Fomes pini (Thore) Lloyd. Considerable variation in the fungi responsible for decay was encountered intraregionally. Stand defect losses varied from 38 to 71%. Some of this variation could be predicted on the basis of the site index determinations of hemlock. Relative to the total incidence and importance of decay, Echinodontium tinctorium decreased and Fomes pini increased in significance with increasing site quality. Sporophores, scars, dead tops, large rotten branches, swollen knots, frost cracks, forked trees, and trunk infections of mistletoe were classed as indicators of significance in relation to hidden defect. Living trees, classed as Suspect or Residual depending on the presence or absence of one or more reliable indicators of defect, were found to differ appreciably in average defect. Within each of the preceding classes decay increased progressively with increasing diameter and decreasing site quality. Immature hemlock was found to be susceptible to appreciable decay and mature stands reached an advanced stage of deterioration at 250 years. Multiple correlation analyses between percentage of decay, site, age, and the relative percentage of Residual trees weighted by volume permitted an estimate of total stand defect within ± 7%.

scholarly journals Juvenile Height Development in Interior Spruce Stands of British Columbia

2000 ◽  
Vol 15 (3) ◽  
pp. 117-121 ◽  
Author(s):  
Gordon D. Nigh ◽  
Bobby A. Love
Keyword(s):  
Decision Making ◽  
British Columbia ◽  
Site Index ◽  
Timber Supply ◽  
Breast Height ◽  
Forest Region ◽  
Interior Spruce ◽  
Spruce Stands ◽  
Age Model ◽  
Height Model

Abstract Good estimates of juvenile heights are important for silviculture and timber supply decision-making. These height estimates are particularly important for estimating the number of years it takes a stand to reach green-up and breast height. Thirty-nine 0.04 ha plots were established in managed juvenile stands of interior spruce in the Prince Rupert Forest Region. Four sample trees in each plot were split longitudinally and height-age data were obtained from the exposed pith nodes or branch whorls. The height-age data were fit to a combined exponential and power function to create a juvenile height model for interior spruce. This model is a function of age and site index. Years to breast height and green-up age models were developed with data generated from the juvenile height model. Forecasts from these models indicate that the time to reach breast height and green-up age is less than previously expected. The juvenile height model, years to breast height model, and green-up age model should be used for site indices above 14.2 m. In addition, the height model should only be used up to total age 20. West. J. Appl. For. 15(3):117-121.

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