Determining the Effects of Biogeoclimatic Properties on Different Site Index Systems of Douglas-fir in the Coastal Pacific Northwest

Site index and height growth curves produced by the major Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) site index studies in the Pacific Northwest are graphically compared. Results indicate that differences in the height growth pattern of Douglas-fir increase with increasing distance between regions. Height growth differences were extremely small between the northern Rockies and the east side of the Cascades and were rather large between the Rockies and the west side of the Cascades. The relatively small differences between the northern Rockies and the Cascade crest fell between these two extremes. Very small differences were also found between Montana and northern Idaho. A second result of the comparisons is that the type of data and the resulting methodology used to develop the site index curve system are strongly related to the similarity of the resulting curves. Curves derived from felled-tree, stem-analysis studies were quite similar to each other, but differed substantially from curves derived by harmonized guide-curve methods. Furthermore, the guide-curve systems produced curves that were surprisingly similar to each other, even though different varieties of Douglas-fir from different regions were being compared. The magnitude of the differences that could be attributed solely to different methods of site curve construction (stem analysis vs. guide curve) was demonstrated to be quite large by applying both methods to the same data. The often untenable assumptions inherent in guide-curve systems appear to affect the shape of the curves more than real regional height growth differences.

Download Full-text

Incorporation of Genetic Gain into Growth Projections of Douglas-Fir Using ORGANON and the Forest Vegetation Simulator

Western Journal of Applied Forestry ◽

10.1093/wjaf/25.2.55 ◽

2010 ◽

Vol 25 (2) ◽

pp. 55-61 ◽

Cited By ~ 11

Author(s):

Peter J. Gould ◽

David D. Marshall

Keyword(s):

Pacific Northwest ◽

Genetic Gain ◽

Growth Models ◽

Regional Growth ◽

Site Index ◽

Douglas Fir ◽

Forest Vegetation ◽

Planting Density ◽

Forest Vegetation Simulator ◽

Stand Management

Abstract Growth models for coast Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco) are generally based on measurements of stands that are genetically unimproved (or woods-run); therefore, they cannot be expected to accurately project the development of stands that originate from improved seedlots. In this report, we demonstrate how early expected gain and genetic-gain multipliers can be incorporated into growth projection, and we also summarize projected volume gains and other aspects of stand development under different levels of genetic gain, site productivity, and initial planting density. Representative tree lists that included three levels of productivity (site index = 100, 125, and 150 ft; base = 50 years)and three initial planting densities (302, 435, and 602 trees/ac) were projected from ages 10 to 60 years under three scenarios using two regional growth models (Stand Management Cooperative version of ORGANON and the Pacific Northwest variant of the Forest Vegetation Simulator). The two models projected similar percentage volume gains for improved seedlots. Seedlots with a genetic worth (GW) of 5% for height and diameter growth were projected to have volume gains of 3.3–5.8% over woods-run stands at 40 years and 2.1–3.2% at 60 years. Volume gains were projected to approximately double when GW was increased from 5 to 10%.

Download Full-text

Prediction of Douglas-fir fertilizer response using biogeoclimatic properties in the coastal Pacific Northwest

Canadian Journal of Forest Research ◽

10.1139/cjfr-2014-0190 ◽

2014 ◽

Vol 44 (10) ◽

pp. 1253-1264 ◽

Cited By ~ 8

Author(s):

K.M. Littke ◽

R.B. Harrison ◽

D. Zabowski ◽

M.A. Ciol ◽

D.G. Briggs

Keyword(s):

Pacific Northwest ◽

Pearson Correlation ◽

Regression Tree ◽

Correlation Coefficients ◽

Basal Area ◽

Site Index ◽

Douglas Fir ◽

Annual Increment ◽

Fertilizer Response ◽

Boosted Regression Tree

Fertilizer response of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) has been related to site and soil properties in the past, but the models have explained only about half of the variation in these investigations. Fertilizer response and percent response after two years were examined, according to mapped and measured biogeoclimatic variables, for 71 Douglas-fir installations in the coastal Pacific Northwest. Paired-tree installations consisted of 12–20 pairs of Douglas-fir trees with one tree fertilized with urea at 224 kg N·ha−1. Pearson correlation coefficients and boosted regression tree (BRT) models were used to determine the best predictor variables and models of Douglas-fir fertilizer response. The BRT models, using the combination of mapped and measured variables, performed the best for predicting fertilizer response. Basal area and volume responses were most related to high forest floor and surface soil carbon to nitrogen ratios. Basal area mean annual increment (MAI) and site index were both negatively correlated with fertilizer response. Also, low basal area MAI was the most important tree measurement for predicting fertilizer response in the BRT models. Installations with many of the predictors from the BRT models (>66% of the model criteria) were found to have a significantly greater fertilizer response than installations with only a few predictors (<33% of the model criteria). These findings support the use of these models for predicting fertilizer response of similar Douglas-fir stands in the coastal Pacific Northwest.

Download Full-text

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.

Download Full-text

BREEDING BIRD RESPONSE TO RIPARIAN BUFFER WIDTH IN MANAGED PACIFIC NORTHWEST DOUGLAS-FIR FORESTS

Ecological Applications ◽

10.1890/1051-0761(2001)011[0840:bbrtrb]2.0.co;2 ◽

2001 ◽

Vol 11 (3) ◽

pp. 840-853 ◽

Cited By ~ 47

Author(s):

Scott F. Pearson ◽

David A. Manuwal

Keyword(s):

Pacific Northwest ◽

Douglas Fir ◽

Riparian Buffer ◽

Breeding Bird ◽

Buffer Width

Download Full-text

Invasive scotch broom alters soil chemical properties in Douglas-fir forests of the Pacific Northwest, USA

Plant and Soil ◽

10.1007/s11104-015-2662-7 ◽

2015 ◽

Vol 398 (1-2) ◽

pp. 281-289 ◽

Cited By ~ 12

Author(s):

Robert A. Slesak ◽

Timothy B. Harrington ◽

Anthony W. D’Amato

Keyword(s):

Pacific Northwest ◽

Chemical Properties ◽

Douglas Fir ◽

Soil Chemical Properties ◽

Scotch Broom ◽

The Pacific

Download Full-text

Predicting Swiss Needle Cast Disease Distribution and Severity in Young Douglas-Fir Plantations in Coastal Oregon

Phytopathology ◽

10.1094/phyto.2003.93.7.790 ◽

2003 ◽

Vol 93 (7) ◽

pp. 790-798 ◽

Cited By ~ 32

Author(s):

Pablo H. Rosso ◽

Everett M. Hansen

Keyword(s):

Prediction Model ◽

Disease Severity ◽

Pacific Northwest ◽

Regression Tree ◽

Douglas Fir ◽

Slope Aspect ◽

Disease Prediction ◽

Needle Cast ◽

Swiss Needle Cast ◽

The Relationship

Swiss needle cast (SNC), caused by the fungus Phaeocryptopus gaeumannii, is producing extensive defoliation and growth reduction in Douglas-fir forest plantations along the Pacific Northwest coast. An SNC disease prediction model for the coastal area of Oregon was built by establishing the relationship between the distribution of disease and the environment. A ground-based disease survey (220 plots) was used to study this relationship. Two types of regression approaches, multiple linear regression and regression tree, were used to study the relationship between disease severity and climate, topography, soil, and forest stand characteristics. Fog occurrence, precipitation, temperature, elevation, and slope aspect were the variables that contributed to explain most of the variability in disease severity, as indicated by both the multiple regression (r 2 = 0.57) and regression tree (RMD = 0.27) analyses. The resulting regression model was used to construct a disease prediction map. Findings agree with and formalize our previous understanding of the ecology of SNC: warmer and wetter conditions, provided that summer temperatures are relatively low, appear to increase disease severity. Both regression approaches have characteristics that can be useful in helping to improve our understanding of the ecology of SNC. The prediction model is able to produce a continuous prediction surface, suitable for hypothesis testing and assisting in disease management and research.

Download Full-text