Modelling the Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) site index from site factors in Portugal

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.

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Comparison and Development of Height Growth and Site Index urves for Douglas-Fir in the Inland Northwest

Western Journal of Applied Forestry ◽

10.1093/wjaf/4.3.85 ◽

1989 ◽

Vol 4 (3) ◽

pp. 85-88

Author(s):

James L. Vander Ploeg ◽

James A. Moore

Keyword(s):

Pseudotsuga Menziesii ◽

Model Development ◽

Analysis Data ◽

Site Index ◽

Height Growth ◽

Douglas Fir ◽

Western Montana ◽

Stem Analysis ◽

Inland Northwest ◽

Central Idaho

Abstract Stem analysis data from Douglas-fir (Pseudotsuga menziesii) collected throughout the inland Northwest were used for testing height growth and site index equations. The equations performed well in northern and central Idaho, northeast Oregon, and northeast Washington on vegetative types similar to those sampled in model development. However, if the equations were applied on drier sites outside the original geographic study area, overestimates of height growth and under-estimates of site index could result. Therefore, revised height growth and site index equations are presented for western Montana and central Washington. West. J. Appl. For. 4(3):85-88, July 1989.

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A New Look at Pruning Coast Douglas-Fir

Western Journal of Applied Forestry ◽

10.1093/wjaf/3.2.46 ◽

1988 ◽

Vol 3 (2) ◽

pp. 46-48

Author(s):

Roger D. Fight ◽

James M. Cahill ◽

Thomas D. Fahey ◽

Thomas A. Snellgrove

Keyword(s):

Interest Rates ◽

Pseudotsuga Menziesii ◽

Computer Software ◽

New Product ◽

Site Index ◽

Douglas Fir ◽

Product Recovery ◽

Financial Returns ◽

New Look

Abstract Pruning of coast Douglas-fir for (Pseudotsuga menziesii var. menziesii) lumber was evaluated by using new product-recovery information and new computer software. The results showed that higher financial returns from pruning are achieved by pruning early in stands that have a higher site index and that will be fertilized. Interest rates and the premium for clear lumber will have major impacts on the dollar return from pruning. West. J. Appl. For. 3(2):46-48, April 1988.

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Growth Response to Fertilization in Young Douglas-Fir Stands

Western Journal of Applied Forestry ◽

10.1093/wjaf/4.4.116 ◽

1989 ◽

Vol 4 (4) ◽

pp. 116-119 ◽

Cited By ~ 2

Author(s):

Linda S. Heath ◽

H. N. Chappell

Keyword(s):

Pseudotsuga Menziesii ◽

Growth Response ◽

Volume Growth ◽

Basal Area ◽

Site Index ◽

Douglas Fir ◽

Intermediate Region ◽

Fertilizer Response ◽

Breast Height ◽

Inverse Effect

Abstract Response surface methodology was used to estimate six-year volume growth response to 1 application of 200 lb nitrogen per acre in unthinned and thinned Douglas-fir (Pseudotsuga menziesii) stands of breast height age (bha) 25 years or less. Regional mean fertilizer response was 16% in unthinned stands and 20% in thinned stands. Site index had an increasingly inverse effect on response as basal area increased in both unthinned and thinned stands. Response varied little over site index in regions of low basal area, decreased moderately as site index increased in the intermediate region, and decreased rapidly in the high basal area region. West. J. Appl. For. 4(4):116-119, October 1989.

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Yield Comparison of Three Douglas-Fir Plantations on Former Farmland in Western Washington

Western Journal of Applied Forestry ◽

10.1093/wjaf/5.4.123 ◽

1990 ◽

Vol 5 (4) ◽

pp. 123-126

Author(s):

Marshall D. Murray ◽

Constance A. Harrington

Keyword(s):

Pseudotsuga Menziesii ◽

Nutrient Availability ◽

Site Index ◽

Douglas Fir ◽

Annual Increment ◽

Volume Yield ◽

Western Washington ◽

Natural Stands ◽

Mean Annual Increment ◽

Enhanced Yield

Abstract Yields of three Douglas-fir (Pseudotsuga menziesii) plantations on former farmland were substantially greater than DFSIM yields for the plantations based on site index estimates from adjacent natural stands. Volume yield per acre of trees 1.6 in. dbh and larger was 40 to 57% greater in the actual plantations than in the simulations. For trees 7.6 in. dbh and larger, volume yield of the actual plantations was 85 to 151% greater than the simulated yields. Mean annual increment of the actual plantations was 56 to 69% greater than the simulated values. In addition, top height was greater in two of the plantations than predicted. Running a second set of simulations with site index estimates based on plantation trees reduced the discrepancy in yields but still resulted in substantial underpredictions. Some possible reasons for enhanced yield of the plantations on former farmland are greater site uniformity, reduced vegetative competition, and increased nutrient availability. West. J. Appl. For. 5(4):00-00, October 1990.

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Assessing the impact of current and projected climates on Douglas-Fir productivity in British Columbia, Canada, using a process-based model (3-PG)

Canadian Journal of Forest Research ◽

10.1139/x09-201 ◽

2010 ◽

Vol 40 (3) ◽

pp. 511-524 ◽

Cited By ~ 36

Author(s):

Nicholas C. Coops ◽

Robbie A. Hember ◽

Richard H. Waring

Keyword(s):

British Columbia ◽

Pseudotsuga Menziesii ◽

Site Index ◽

Douglas Fir ◽

Climatic Variation ◽

Climate Forecasts ◽

Fine Spatial Resolution ◽

Viable Approach ◽

The Impact ◽

Process Based Models

Predicted climate change is expected to significantly affect tree growth in many areas. We used a process-based model (Physiological Principles for Predicting Growth, 3-PG) to evaluate how climatic variation might alter growth of Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco and Pseudotsuga menziesii (Mirb.) Franco var. menziesii ) across biogeoclimatic zones in British Columbia. The results indicate that there will be significant changes in site index (defined as the height (in metres) of dominant trees at 50 years) over this century. In the interior, a reduction in site index is likely, particularly in stands with mid-range values of site index (25–30 m), with many of the interior bioecoclimatic zones predicted to experience a gradual mean decrease in site index by up to 10%. Individual sites may decrease by as much as 40% from current values. In contrast, site index along the coast overall is predicted to increase to a maximum of 43 m by 2080. In the Coastal Western Hemlock zone, however, mean site index is likely to increase from 26 m to only 34 m. We believe that combining process-based models with fine-spatial resolution climate forecasts offers a viable approach to assess future changes in forest productivity.

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A Generalized Height-Diameter Equation for Coastal California Species

Western Journal of Applied Forestry ◽

10.1093/wjaf/3.4.113 ◽

1988 ◽

Vol 3 (4) ◽

pp. 113-115 ◽

Cited By ~ 19

Author(s):

Bruce E. Krumland ◽

Lee C. Wensel

Keyword(s):

Pseudotsuga Menziesii ◽

Site Index ◽

Douglas Fir ◽

Sequoia Sempervirens ◽

Small Samples ◽

Diameter Distribution ◽

Northern California ◽

Local Volume ◽

Total Height ◽

Volume Table

Abstract The equation H = Hm exp [-b(D-c - Dm-c)] is proposed for estimating the total height of trees on growth and inventory plots. This estimator requires only the computation of average dbh (Dm) and average total height (Hm) of a sample of trees selected from the upper one-fifth of the stand diameter distribution. The procedure is also efficient because this stand component is also used to estimate site index. With small samples, these equations were found to be accurate in local volume table construction. Results are illustrated using redwood (Sequoia sempervirens) and Douglas-fir (Pseudotsuga menziesii) data from northern California. West. J. Appl. For. 3(4):113-115, October 1988.

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Estimating Dominant Height and Site Index of Even-Aged Interior Douglas-Fir in British Columbia

Western Journal of Applied Forestry ◽

10.1093/wjaf/7.1.20 ◽

1992 ◽

Vol 7 (1) ◽

pp. 20-25 ◽

Cited By ~ 8

Author(s):

James S. Thrower ◽

James W. Goudie

Keyword(s):

British Columbia ◽

Linear Model ◽

Pseudotsuga Menziesii ◽

Site Index ◽

Logistic Function ◽

Height Growth ◽

Douglas Fir ◽

Stem Analysis ◽

Inland Empire ◽

Dominant Height

Abstract Height-age and site-index curves were developed from stem analysis of 262 Douglas-fir trees (Pseudotsuga menziesii var. glauca) from 68 plots in the Interior Douglas-fir, Interior Cedar-Hemlock, and Sub-boreal Spruce Biogeoclimatic zones in the interior of British Columbia. Plots ranged in site index from about 8 to 30 m and in age from about 60 to 350 years; however, the analyses were limited to data up to 100 years of age. A conditioned logistic function was selected for predicting height, and a linear model was selected for predicting site index. The curves are similar to those developed in comparable studies in the Inland Empire, but differ substantially from curves developed in British Columbia from temporary sample plots. This study supports previous observations that the pattern of height growth for a given site index varies among ecologically different areas. West. J. Appl. For. 7(1):20-25.

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Physiologically derived predictions of Douglas-fir site index in British Columbia

The Forestry Chronicle ◽

10.5558/tfc85733-5 ◽

2009 ◽

Vol 85 (5) ◽

pp. 733-744 ◽

Cited By ~ 7

Author(s):

Nicholas C Coops ◽

Robbie A Hember

Keyword(s):

British Columbia ◽

Soil Water ◽

Pseudotsuga Menziesii ◽

Tree Height ◽

Site Index ◽

Douglas Fir ◽

Forest Growth ◽

Individual Tree ◽

Forest Growth Model ◽

Wide Range

Both the coastal and interior varieties of Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco; Pseudotsuga menziesii var. glauca) are found throughout a wide range of environmental conditions across British Columbia. The species is long-lived and can grow rapidly to standing volumes that approach the highest recorded among temperate conifers. Understanding the growth of the species across British Columbia, and its site index (defined as individual tree height at 50 m) is important for forest managers for both production and conservation objectives. To date, predictions of site index have traditionally been derived from forest inventory using estimates of species, height and age combined with the appropriate height–age model. More recently, process-based modelling has offered a viable alternative approach due to increased computing power, model simplifications and availability of input data. In this paper we applied a physiological forest growth model, 3-PG (Physiological Principles Predicting Growth) to predict and map site index of Douglas-fir across British Columbia at 1-km cell resolution. Our model predictions were scaled-up and compared to independent estimates of average site index for subzones from the British Columbia Biogeoclimatic Ecosystem Classification (BEC) system. Results indicated the 3-PG predictions closely matched those summarized by the BEC sub-zones (r = 0.86, p<0.001, SE = 3.0m). Predicted environmental limitations of growth suggest that the coastal variety of the species is most severely affected by temperature and frost constraints, and in some locations, soil water stress, whereas the interior variety is principally restricted by soil water availability. The proposed modelling approach complements ecological classifications and offers the potential to identify the most favourable sites for management of other native tree species under current and projected climates. Key words: Douglas-fir, site index, physiological modelling, 3-PG model, forest productivity, British Columbia, Canada

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Preliminary DRIS norms for coastal Douglas-fir soils in Washington and Oregon

Canadian Journal of Forest Research ◽

10.1139/x95-025 ◽

1995 ◽

Vol 25 (2) ◽

pp. 208-214 ◽

Cited By ~ 2

Author(s):

J.S. Shumway ◽

H.N. Chappell

Keyword(s):

Basal Area ◽

Site Index ◽

Douglas Fir ◽

Integrated System ◽

N Fertilizer ◽

Soil Test ◽

Fertilizer Response ◽

Response Data ◽

Limiting Nutrient ◽

Diagnostic Work

The Diagnosis and Recommendation Integrated System (DRIS) has been used successfully in agricultural crops and holds promise for use in forest stands. This study used soil tests to develop DRIS norms and evaluate their effectiveness in coastal Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) forests. DRIS norms for nitrogen, phosphorus, potassium, and calcium were developed using soil test and site index data from 72 soil series that commonly support Douglas-fir in western Washington. The norms were tested using soil test and stand basal area growth response data from 20 thinned and 30 unthinned N fertilizer test sites in coastal Washington and Oregon. Response to urea fertilizer in thinned stands averaged 34% and 43% for 224 and 448 kg N•ha−1, respectively, when N was identified as the most limiting nutrient. When N was not the most limiting nutrient, N response averaged 8% and 10% for 224 and 448 kg N•ha−1, respectively. Results were similar in unthinned stands and thinned stands, although response to fertilizer appeared to be slightly less in unthinned stands when N was the most limiting nutrient. DRIS correctly classified 25 of the 33 sites (76%) where N fertilizer increased growth by more than 15%. More importantly, 13 of the 17 (76%) sites that responded by less than 15% were correctly identified by DRIS. The results clearly indicate that N fertilizer response is dependent on the interactions (balance) between soil nutrients at a given site. Future soil diagnostic work needs to focus on techniques, like DRIS, that provide an assessment of these interactions.

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