scholarly journals IS HEIGHT/AGE A RELIABLE INDEX OF SITE?

1961 ◽  
Vol 37 (2) ◽  
pp. 144-150 ◽  
Author(s):  
A. B. Vincent

Uses of the total-height/total-age relationship and the growth-intercept method in defining site quality are discussed briefly. Factors affecting height growth of the trees such as animal, insect, and frost damage, along with stand density and initial suppression, are discussed. Attention is drawn to their influences on the height-age relationship. It is suggested that the growth-intercept method of obtaining site quality may be useful in some circumstances.

1990 ◽  
Vol 7 (1) ◽  
pp. 27-30 ◽  
Author(s):  
James H. Brown ◽  
Charles A. Duncan

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.


1986 ◽  
Vol 16 (3) ◽  
pp. 648-650 ◽  
Author(s):  
R. Bruce Harding

Terminal leader failure from bud mortality occurred in 46% of plantation white spruce (Piceaglauca (Moench) Voss) trees, 19–43 years old. Frost damage was identified as the causal factor of bud mortality, with all plantations being established from seed sources of local origin. Large differences in terminal bud failure rates were noted between year of observation, tree size class, and stand age-class. Dominant trees, 33–43 years old, had a 3 year failure rate ranging from 16 to 51 %. For dominant trees, an 18% (9 cm) height growth reduction per year of incidence was noted. The lateral replacement process could account for greater than a 2 m height reduction for dominants at age 50 years, confounding estimates of potential site quality. The height growth of overtopped trees responded differently to frost damage than dominants, with replacement laterals averaging 38% (8 cm) greater height growth than apical terminals of undamaged trees.


2006 ◽  
Vol 36 (9) ◽  
pp. 2179-2188 ◽  
Author(s):  
Jin-ping Guo ◽  
Jian R Wang

Accurate estimates of forest productivity are required for sustainable forest management. Sixty-five jack pine (Pinus banksiana Lamb.) plantations (<50 years of age) were sampled to develop height growth and variable growth intercept (GI) models for jack pine plantations in northern Ontario, Canada. Based on the residual plots and model-fitting statistics, these models can be recommended for estimating site index (SI) of young (<40 years) jack pine plantations. To compare SI of plantations with that of natural stands, we used stem-analysis data from 383 plots of natural jack pine stands (aged 50–157 years) from the same geographic region to develop the GI models for natural stands. Also, polymorphic SI curves were developed for young (<40 years) plantations in northern Ontario. These SI curves were different from those for natural stands. Jack pine plantations had a higher site quality (SI) than did the original natural stands on the similar sites. The SI curves developed from natural stands should not be used to predict growth and yield of jack pine plantations before they are calibrated for jack pine plantations. These GI models will be used to estimate SI for silviculture and forest-management planning.


2000 ◽  
Vol 30 (9) ◽  
pp. 1472-1475 ◽  
Author(s):  
David W MacFarlane ◽  
Edwin J Green ◽  
Harold E Burkhart

The height growth of dominant trees in plantations is often assumed to be independent of initial planting density. This assumption allows for the use of dominant tree height as an index of site quality. We found that this assumption was false for the seven tallest trees in 184 even-aged loblolly pine (Pinus taeda L.) stands, planted at nine initial planting densities, at four different geographic locations. A strong, highly significant negative correlation was found between dominant height and initial planting density for stands 14 and 16 years of age. This leads to large differences in predicted site index for stands with different initial planting densities planted at the same geographic location. Use of these site indices to predict yield produced large differences in predicted yield (m3/ha) at age 25. These results provide strong evidence for density-dependent height growth, even for dominant trees in the stand, and suggest that site index, used as a measurement of site quality, is confounded with stand density.


2011 ◽  
Vol 28 (3) ◽  
pp. 129-137
Author(s):  
Martin M. Kwiaton ◽  
Jian R. Wang ◽  
Douglas E.B. Reid

Abstract Site quality is a key component of growth and yield models because height growth rates are known to be influenced by available site resources. Accurate prediction of future growth and yield requires site quality information for both plantations and natural stands. The forest industry in northern Ontario relies on high-quality wood and fiber from black spruce (Picea mariana Mill. B.S.P.); therefore, these tools are essential to ensure sustainable forest management. Although there are site index (SI) models for natural-origin black spruce stands in northern Ontario, models for estimating site quality of young black spruce plantations have not been developed. We used stem analysis data collected from 62 plantations (>40 years of age) of pure black spruce across northern Ontario to develop height growth, SI, and variable growth intercept models. The distinct height growth patterns we observed may be attributed to early silvicultural treatments (site preparation and herbicide) in plantations allowing black spruce trees to attain breast height (1.3 m) faster than in fire-origin stands in northern Ontario. Our models can be used to estimate site quality of black spruce plantations, a key consideration for silviculture and forest management planning. We also compare our managed stand SI model to one we developed from a comparable subset of data from black spruce growing in unmanaged stands and propose a method to assign an SI with a common base age to pure upland black spruce stands regardless of origin.


1988 ◽  
Vol 5 (2) ◽  
pp. 91-93 ◽  
Author(s):  
Timothy R. Bottenfield ◽  
David D. Reed

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.


Forests ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1155 ◽  
Author(s):  
Mark O. Kimberley ◽  
Michael S. Watt

Empirical growth models are widely used to predict the growth and yield of plantation tree species, and the precise estimation of site quality is an important component of these models. The most commonly used proxy for site quality in growth models is Site Index (SI), which describes the mean height of dominant trees at a specified base age. Although SI is widely used, considerable research shows significant site-dependent variation in height for a given volume, with this latter variable more closely reflecting actual site productivity. Using a national dataset, this study develops and describes a stand-level growth and yield model for even-aged New Zealand-grown coast redwood (Sequoia sempervirens). We used a novel modelling approach that quantifies site quality using SI and a volume-based index termed the 300 Index, defined as the volume mean annual increment at age 30 years for a reference regime of 300 stems ha−1. The growth model includes a number of interrelated components. Mean top height is modelled from age and SI using a polymorphic Korf function. A modified anamorphic Korf function is used to describe tree quadratic mean diameter (Dq) as a function of age, stand density, SI and a diameter site index. As the Dq model includes stand density in its formulation, it can predict tree growth for different stand densities and thinning regimes. The mortality model is based on a simple attritional equation improved through incorporation of the Reineke stand density index to account for competition-induced mortality. Using these components, the model precisely estimates stand-level volume. The developed model will be of considerable value to growers for yield projection and regime evaluation. By more robustly describing the site effect, the growth model provides researchers with an improved framework for quantifying and understanding the causes of spatial and temporal variation in plantation productivity.


Author(s):  
Pavel Bednář ◽  
Jakub Černý

This paper analyses the development of beech plantations aged 7 to 18 years that were planted in gap cuts (0.1–0.25 ha; ISF 50%), clear cuts (0.5–1.0 ha; ISF 87%) and finally underplanted areas in shelterwood cuts in mature spruce stands (G = 22–26 m2/ha; ISF 28%). The research consisted of the following analyses: height growth, diameter growth and beech quality development. We used standard statistical tools (p < 0.05) for evaluating height and diameter growth, which showed significant differences in both characteristics (total height and DBH) within 7-year-old and 13-year-old plantations grown in all three regeneration treatments. The tallest beech trees with greatest DBH at the age of 7 and 13 were found in clearings whereas shortest and thinnest trees grew in shelterwoods. However, at the age of 18, there was no significant different between gap cut and clear cut in both parameters. The best quality was observed in shelterwoods.


1997 ◽  
Vol 12 (1) ◽  
pp. 5-8
Author(s):  
Gordon D. Nigh

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.


1988 ◽  
Vol 3 (3) ◽  
pp. 70-74 ◽  
Author(s):  
Frederick W. Smith ◽  
Thomas Schuler

Abstract Site quality and growth-growing stock relations were developed for southwestern woodlands of pinyon (Pinus edulis) and one-seed juniper (Juniperus monosperma) or Utah juniper (J. osteosperma). Anamorphic height-age site index curves for pinyon were developed from a regional sample of 60 woodlands. Site index was unaffected by variation in stocking and was correlated with woodland yield when used in conjunction with density. Pinyon and juniper PAI, when taken separately, were highly correlated with stand density and pinyon site index. Pinyon was twice as productive as juniper at similar stand densities. Pinyon and juniper yields in woodlands of average density and site index were estimated at 0.29 and 0.15 m3ha-1y-1. At high densities pinyon and juniper yields increased to 0.61 and 0.31 m3ha-1y-1 Pinyon and juniper yields appeared independent of the density of the other species in an individual woodland. Maximum yield of dense mixed species woodlands on average sites was 0.78 m3ha-1y-1, and occurred when pinyon constituted 65% of woodland density. West. J. Appl. For. 3(3):70-74, July 1988.


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