Height Growth and Site Index Curves for Douglas-Fir in the Siuslaw National Forest, Oregon

1989 ◽  
Vol 4 (4) ◽  
pp. 136-142 ◽  
Author(s):  
Joseph E. Means ◽  
Thomas E. Sabin

Abstract On the Siuslaw National Forest in the central Oregon Coast Range we performed stem analysis of 55 trees selected with the criteria used by the forest. Height growth patterns of these trees were significantly different (α = 0.05) from commonly used regional height growth curves. Height growth patterns also differed significantly among groups of floristically similar plant associations in the Siuslaw National Forest. We constructed height growth and site index curves for two classes of plant associations having different height growth curve forms and for the combined data. Forest managers should consider building local height-growth and site-index curves if these are important in estimating stand yield or site productivity. West. J. Appl. For. 4(4):136-142, October 1989

1992 ◽  
Vol 7 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Kelsey S. Milner

Abstract Height growth patterns from several published site curve sytems for ponderosa pine (Pinus ponderosa), Douglas-fir (Pseudotsuga menziesii var glauca), western larch (Larix occidentalis) and lodgepole pine (Pinus contorta var latifolia) were compared to stem analysis data from western Montana. Most of the published curves had height growth patterns that differed significantly from those in the data. The magnitude of the deviations often varied by level of site index; this appeared to be related to differences in the range of site qualities sampled. Those curves constructed from stem analysis data from geographically similar populations compared most closely. Curves constructed using guide curve techniques showed a consistent tendency to underpredict heights at greater ages. New site index and height growth curves are presented for each species. West. J. Appl. For. 7(1):9-14.


1989 ◽  
Vol 19 (2) ◽  
pp. 215-224 ◽  
Author(s):  
Willard H. Carmean ◽  
Daniel J. Lenthall

Height-growth patterns for jack pine (Pinusbanksiana Lamb.) were studied using stem analyses from dominant and codominant trees on 141 plots in north central Ontario. All plots were in natural, well-stocked, even-aged stands 50 years of age or older. Data from 32 of the 141 plots were randomly selected to confirm results, the remaining 109 plots were used for computing the curves. Height-growth curves were developed using a five-parameter Chapman–Richards nonlinear regression that expressed height as a function of age and site index. A site-index prediction equation was also computed using a similar model that expressed site index as a function of age and tree height. Estimated site index using height-growth curves based on the 109 computation plots agreed closely with site index observed from stem analyses on the 32 confirmation plots. Major results were as follows: (i) height-growth curves based on breast-height age were more accurate than curves based on total age; (ii) polymorphic height-growth patterns were related to site index, becoming more curvilinear as site index increased; (iii) average height-growth patterns were similar for jack pine growing on four glacial landforms: shallow and deep moraines, outwashed glacial sands, and lacustrine clays and silts; and (iv) height-growth patterns for ages less than 50 years were very similar to patterns of the commonly used Plonski curves for jack pine site classes in Ontario, but after 50 years, height growth was somewhat better for all sites than predicted by the Plonski curves.


1993 ◽  
Vol 10 (3) ◽  
pp. 132-136 ◽  
Author(s):  
Boris Zeide

Abstract Construction of new site index curves is often justified by a lack of growth information for a given species and site. This justification presumes that there is a one-to-one correspondence between growth pattern and stand conditions which are determined by numerous genetic and ecological factors together with their complex interactions. Because these factors are combined in an infinite number of ways, each stand is unique and needs its own site index curve. The effort required for collecting growth information would be prohibitive. This effort is also unnecessary because many existing curves coincide with each other and are, therefore, redundant. Differences in species, site, and construction methods do not prevent the appearance of the same growth patterns. These facts indicate that unique growth conditions do not mean that each stand has a unique growth pattern. Therefore, a more productive approach to growth modeling consists of distilling these patterns from existing curves and yield tables rather than piling up more new site index curves. Earlier investigations showed that the diversity in growth curves can be reduced to a small number (15-30) of growth types. The present study demonstrates that the number of types can be further reduced to 3-5 without sacrificing accuracy of growth predictions. North. J. Appl. For. 10(3):132-136.


2004 ◽  
Vol 19 (3) ◽  
pp. 154-159 ◽  
Author(s):  
G. Geoff Wang ◽  
Shongming Huang ◽  
David J. Morgan

Abstract Based on the provincial stem analysis and permanent sample plot (PSP) data of 1,580 felled dominant and codominant trees, height growth patterns of lodgepole pine were compared among the three major natural subregions [Sub-Alpine (SAL), Upper Foothills (UFH), and Lower Foothills (LFH)] in Alberta. The comparison used the ratio of heights at 70 and 30 years of breast height age (Z ratio) as a quantitative measure of height growth pattern (i.e., the response variable), site index (height at breast height age of 50 years) as the covariate, and natural subregion as the factor. Results indicated that: (1) the height growth pattern in the SAL natural subregion was significantly different from other natural subregions; and (2) no significant differences in height growth pattern were found between other natural subregions. Two polymorphic height and site index curves were developed: one for the SAL natural subregion and the other for the UFH and LFH natural subregions. Comparisons between the two curves and the previously developed provincial curve indicated that, for the same site index, trees in the SAL subregion grow consistently slower after 50 years. When the provincial height and site index curve was applied to the SAL natural subregion, large differences (≤14%) in gross volume estimation were found. However, volume estimation differences were very small (<2%) when the provincial curve was applied to the other two natural subregions. It is recommended that the natural subregion-based curves should be used for predicting lodgepole pine site index or height at any age in the SAL natural subregion. West. J. Appl. For. 19(3):154–159.


2001 ◽  
Vol 77 (1) ◽  
pp. 141-150 ◽  
Author(s):  
Willard H. Carmean ◽  
G. Hazenberg ◽  
G. P. Niznowski

Stem-analysis data from dominant and codominant trees were collected from 383 plots located in fully stocked, even-aged, undisturbed mature jack pine stands. Separate site index curves were independently formulated for four regions of northern Ontario using the Newnham constrained nonlinear regression model; these formulations were used for comparing regional site index curves at three levels of site index (10 m, 15 m and 20 m).Comparisons showed that no significant differences existed between the four regional curves as well as with previously published site index curves for the North Central Region. Each of the four regions had similar polymorphic height-growth patterns; therefore, data for the four regions were combined and a single formulation was used to develop a polymorphic set of site index curves for all of northern Ontario. We found that poor sites in each region had almost linear height growth up to 100 years breast-height age, but for each region height growth became more curvilinear with increasing site index. The recommended site index curves for northern Ontario are based on a formulation using only data from plots 100 years and less but this formulation was not significantly different from a formulation using only data from plots 80 years and less, or a formulation that included all data from plots older than 100 years breast-height age.Comparisons were made between our northern Ontario curves and other jack pine site index curves for Ontario as well as curves for other areas of Canada and the United States. These comparisons generally showed considerable older age differences. Reasons for these differences are uncertain but could be due to differences in the amount and kind of data used for these other curves, could be due to differences in analytical methods, or could be due to regional differences in climate, soil and topography. Key words: site quality evaluation, polymorphic height growth, regional site index curves, site index prediction equations, comparisons among site index curves.


2004 ◽  
Vol 21 (4) ◽  
pp. 173-179 ◽  
Author(s):  
Peter R. Hannah

Abstract The structure and growth of northern white cedar (Thuja occidentalis) was studied in 16 stands on wet sites in Vermont. White cedar and associate species representing the range in diameter were felled for stem analysis. Height growth curves were constructed. Structure of white cedar stands on wet sites in Vermont is often even-aged with a relatively uniform canopy due to restocking of former agricultural land, or two-aged, or multiaged, depending on degree of harvesting and other disturbances. On bog and swamp sites, cedar may reach less than 25 ft in height in 50 years whereas on upland sites wet only a portion of the growing season, they may reach 50 ft or greater in height. On well-drained upland sites, height growth may be greater, but cedar most likely may be displaced by other conifers and hardwoods. Basal area in pure and well-stocked maturing stands may exceed 300 ft2, and volumes can exceed 12,000 ft3/ac. In high-density stands, there is usually little understory. Very small amounts of cedar regeneration were observed in the stands studied. Some of the stands had a distinct browse line, and deer are presumed to have a major impact on cedar regeneration. All cedar stands are recognized as being of great importance as deer wintering areas. On the low-quality swamp and bog sites, minimal and careful harvest of cedar should be done to maintain deer habitat, integrity of the tree canopy, and associated understory vegetation. On sites with less water restrictions than in swamps and bogs, harvesting practices to maintain wildlife habitat and assure regeneration and thinning and pruning to improve growth rate and value of harvested wood should be considered. North. J. Appl. For. 21(4):173–179.


1991 ◽  
Vol 21 (10) ◽  
pp. 1466-1474 ◽  
Author(s):  
I. S. Alemdag

Based on stem analyses, national site-index equations and height-growth equations for white spruce (Piceaglauca (Moench) Voss) were developed covering an area from the Yukon to Newfoundland. The objective was to construct a single set of curves for each relationship by combining all regions, instead of separate curves for individual provinces or regions. The results of these tests indicated that the objective could be reached without any significant loss of accuracy. In developing the equations a modified form of the Chapman–Richards function was employed, and results are presented in tabular and graphical forms.


1996 ◽  
Vol 72 (2) ◽  
pp. 193-198 ◽  
Author(s):  
K. Klinka ◽  
H. Y. H. Chen ◽  
Q. Wang ◽  
R. E. Carter

Stem analysis data from even-aged Engelmann spruce (Picea engelmannii Parry ex Engelm.) and subalpine fir [Abies lasiocarpa (Hook.) Nutt.] stands on zonal sites in the Engelmann Spruce—Subalpine Fir biogeoclimatic zone of British Columbia were used to examine the relationships of site index and height growth and elevation, latitude, and longitude. Elevation and latitude were found to be strongly negatively correlated with site index of both study species. Spruce site index (bh age 50) was predicted to decrease 2.9 m and fir site index 2.5 m with every 100 m and 1° increase in elevation and latitude, respectively; however, (i) site index of both species appeared to decline faster with increasing latitude than elevation, and (ii) decrease appeared to be faster for spruce than for fir. Comparison of height growth curves for stands on zonal and azonal sites with similar site index from different elevations and latitudes suggested that there are probably inconsequential differences between the shape of curves for either species. These findings imply that (i) subalpine fir is better adapted to subalpine boreal climates than Engelmann spruce and (ii) development of polymorphic site index curves for estimating site index of both species may be appropriate. Key words: elevation, latitude, longitude, site index, height growth, Abies lasiocarpa, Picea engelmannii, Engelmann Spruce—Subalpine Fir zone


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