scholarly journals Site index conversion equations for mixed trembling aspen and white spruce stands in northern British Columbia

Silva Fennica ◽  
2002 ◽  
Vol 36 (4) ◽  
Author(s):  
Gordon Nigh
2000 ◽  
Vol 15 (3) ◽  
pp. 117-121 ◽  
Author(s):  
Gordon D. Nigh ◽  
Bobby A. Love

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.


2012 ◽  
Vol 42 (8) ◽  
pp. 1566-1576 ◽  
Author(s):  
Derek Joseph Lawrence ◽  
N. Luckai ◽  
W.L. Meyer ◽  
C. Shahi ◽  
A.J. Fazekas ◽  
...  

Mixedwood forests of white spruce ( Picea glauca (Moench) Voss) and trembling aspen ( Populus tremuloides Michx.) may possess ecological advantages over monospecific white spruce stands. Belowground competition may be reduced through vertically stratified roots; facilitation of growth may occur in upper soil layers through nutrient-rich trembling aspen litterfall. These effects may incentivize white spruce to preferentially exploit upper soil layers in mixedwood stands, resulting in wider root systems. This research contrasted white spruce fine root (diameter <2 mm) distributions in organic layers of white spruce and mixedwood stands. Research occurred at the Fallingsnow Ecosystem Project site in northwestern Ontario. Eighteen plots represented mixedwood and pure white spruce stands. Trees were mapped; foliage and root samples were collected. Roots were separated by species and scanned to determine length. Simple sequence repeat DNA profiles were determined for all white spruce trees and for 45 white spruce root fragments per plot. Root and tree DNA profiles were matched; corresponding distances were calculated. Most (80%) root fragments were within 3.2 m of tree stems. Root prevalence decreased rapidly with distance. Organic layer pH was significantly less acidic in mixedwood plots, but only in one block. A subtle significant trend towards wider root distributions occurred in mixedwood stands.


1993 ◽  
Vol 23 (6) ◽  
pp. 1233-1239 ◽  
Author(s):  
David Paré ◽  
Keith Van Cleve

Nutrient content and biomass of aboveground annual production, and nutrient content of total aboveground biomass, of 14-year-old assemblages of plants developing on harvested white spruce (Piceaglauca (Moench) Voss) sites were estimated by vegetation harvesting and compared with values previously measured in mature white spruce stands. The aboveground biomass production of 14-year-old regenerating trembling aspen (Populustremuloides Michx.) clumps was 3 times higher than the aboveground production of mature white spruce stands, while the aboveground production of other regenerating communities was lower or equivalent to the production of mature white spruce. However, the nutrient content of aboveground current biomass was greater in all regenerating communities than in mature white spruce stands, except on regenerating sites where the forest floor was absent. The amount of nutrient incorporated in current aboveground biomass was 5 times greater in trembling aspen clumps than in mature white spruce stands. Furthermore, the total N, P, and K content of aboveground vegetation corresponded, in 14-year-old trembling aspen clumps, to a value that ranged from 50 to 109% of the amount found in the aboveground biomass of mature white spruce forests, while this value ranged from 4 to 14% on other regeneration types. Trembling aspen and balsam poplar (Populusbalsamifera L.) both showed the greatest concentrations of N and P in foliar litter fall. These observations suggest that the development of a trembling aspen clump after clear-cutting contributes to the acceleration of nutrient cycling. On the other hand, the development of herbaceous communities during the same period after clear-cutting was accompanied by much lower nutrient cycling rates in the aboveground portion of the vegetation.


Forests ◽  
2015 ◽  
Vol 6 (12) ◽  
pp. 4573-4587 ◽  
Author(s):  
Valentín Reyes-Hernández ◽  
Philip Comeau

2006 ◽  
Vol 82 (6) ◽  
pp. 819-824 ◽  
Author(s):  
Zhili Feng ◽  
Kenneth J Stadt ◽  
Victor J Lieffers ◽  
Shongming Huang

The goal of this study was to link the growth of juvenile white spruce stands with an estimate of their site index. We applied a previously developed technique for correcting the height bias created by dominance switching among juvenile trees before trees reached the site index base age (50 years at breast height), using stem analysis data of white spruce from five mixedwood stands in central Alberta. For white spruce of approximately 15 years total age, we found the height of the current top height trees was approximately 14% greater than the height of the top height trees that would be selected close to breast height age 50. This height correction is essential to avoid an overestimate of site index. Secondly, to avoid the difficulties of determining breast height age or growth increment required for juvenile site index determination, we developed a linkage to site index using data from 168 white spruce trees that were longitudinally sectioned along the pith, selected from juvenile (age 6–15) spruce stands. Using this new equation, coupled with the correction for bias, we found that site index for white spruce from 49 test stands in Alberta, ranged from 9.0 to 31.8 m at base age 50, with a mean of 17.8 m; these values are in the range for spruce in mixedwood stands in Alberta. Key words: juvenile stand, height age curve, height bias adjustment, site index


2008 ◽  
Vol 38 (5) ◽  
pp. 1211-1222 ◽  
Author(s):  
Giovanni Leonelli ◽  
Bernhard Denneler ◽  
Yves Bergeron

Growth–climate relationships were analyzed for 15 stands of trembling aspen ( Populus tremuloides Michx.) along a productivity gradient in northeastern British Columbia. Productivity was evaluated with a site index model whose values varied between 6.65 and 26.93 m height at age 50 years. To assess the role of climate on radial growth, we built a tree-ring chronology for each site and then performed a dendroclimatic analysis by means of bootstrapped correlation functions using monthly and annual climatic variables. We found that trembling aspen sensitivity to climate varied across stands with different productivities in the study area. At the more productive sites, trees were more sensitive to climate, and ring widths were positively correlated, particularly with summer month precipitation prior to the year of growth. The different responses to climate along the productivity gradient are likely related to the differences in substrate properties; substrates at the more productive sites are richer in nutrients and have a better water holding capacity than those of the less productive sites. Our study suggests that the effects of future climate change on tree growth may not only increase towards the limit of a species distribution, but also towards richer and wetter stands.


2004 ◽  
Vol 34 (11) ◽  
pp. 2277-2283 ◽  
Author(s):  
Philip G Comeau ◽  
Cosmin N Filipescu ◽  
Richard Kabzems ◽  
Craig DeLong

We examined the growth of white spruce planted underneath a 33-year-old stand of trembling aspen following thinning and fertilization. Thinning the stand to 2000 stems·ha–1 resulted in increased light reaching spruce seedlings and significant increases in height and diameter growth of seedlings over that observed in either the unspaced or 3000 stems·ha–1 treatments. Fertilization (applied 3 years prior to planting) stimulated development of understory vegetation and did not benefit the planted spruce. While growth was improved by thinning, the benefits of the thinning treatment to establishment of white spruce appeared to be small, and amounted to increasing seedling height from 62 cm (unthinned) to 73 cm (thinned to 1000 or 2000 stems·ha–1) at the end of 5 years. Results indicated that when stands are thinned for the purpose of accelerating growth rates of underplanted spruce, residual basal areas above 25 m2·ha–1 should be retained to suppress growth of understory vegetation. Comparison of height at age 5 for seedlings planted under untended stands at Fort Nelson with three sites near Dawson Creek indicated no differences between locations, when height at the time of planting was included as a covariate.


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