scholarly journals Shifts in Foliage Biomass and Its Vertical Distribution in Response to Operational Nitrogen Fertilization of Douglas-Fir in Western Oregon

Forests ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 511 ◽  
Author(s):  
Jacob D. Putney ◽  
Douglas A. Maguire
Keyword(s):  
Vertical Distribution ◽  
Nitrogen Fertilization ◽  
N Fertilization ◽  
Douglas Fir ◽  
Tree Level ◽  
Stem Volume ◽  
Parameter Estimates ◽  
Growth Responses ◽  
Basal Diameter ◽  
Dormant Season

Nitrogen (N) fertilization is a commonly applied silvicultural treatment in intensively managed coast Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) plantations. Field trials were established in a randomized complete block design by Stimson Lumber Company (Gaston, Oregon), to test the economic viability of N fertilization on their ownership and to better understand Douglas-fir growth responses. The 23 stands comprising the trials were Douglas-fir dominated, had a total age of 16–24 years, had been precommercially thinned, and had a density of 386–1021 trees ha−1. Fertilizer was applied aerially at a rate of 224 kg N ha−1 as urea during the 2009–2010 dormant season. In the dormant season of 2016–2017, seven growing seasons following application, 40 trees were felled and measured with the objective of assessing crown attributes and aboveground allometrics. Branch-level foliage mass equations were developed from 267 subsampled branches and were applied to the 40 felled sample trees on which the basal diameter and height of all live branches were measured, allowing estimation of both the total amount of foliage and its vertical distribution. A right-truncated Weibull distribution was fitted to data, with the truncation point specified as the base of live tree crown. The resulting tree-level parameter estimates were modeled as functions of tree-level variables. Stand-level factors not explicitly measured were captured through the use of linear and nonlinear mixed-effects models with random stand effects. Fertilization resulted in more total crown foliage mass in the middle crown-third and caused a downward shift in the vertical distribution of foliage, with implications for feedback responses in crown development and photosynthetic capacity. Defining the morphological responses of Douglas-fir crowns to nitrogen fertilization provides a framework for studying influences on stand dynamics and should ultimately facilitate improved site-specific predictions of stem-volume growth.

Influence of Swiss needle cast on foliage age-class structure and vertical foliage distribution in Douglas-fir plantations in north coastal Oregon

2006 ◽  
Vol 36 (6) ◽  
pp. 1497-1508 ◽  
Author(s):  
Aaron R Weiskittel ◽  
Douglas A Maguire ◽  
Sean M Garber ◽  
Alan Kanaskie
Keyword(s):  
Vertical Distribution ◽  
Douglas Fir ◽  
Parameter Estimates ◽  
Class Structure ◽  
Needle Cast ◽  
Age Class ◽  
Relative Contribution ◽  
Crown Structure ◽  
Growth Decline ◽  
Swiss Needle Cast

Swiss needle cast (SNC) causes premature loss of foliage and subsequent growth decline in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Although the mechanisms leading to this growth decline include loss of photosynthetic surface area and physiological disruption of surviving foliage, estimating the relative contribution of these two primary sources requires precise quantification of SNC effects on total foliage mass, foliage age-class structure, and vertical foliage distribution. The effect of SNC severity on these crown structural attributes was tested across a range of stand densities and site qualities in 10- to 60-year-old plantations in north coastal Oregon. Foliage mass in each age-class was sampled at the branch level, and the resulting equations were applied to all live branches on intensively measured sample trees. Vertical distribution of each foliage age-class was described by a beta distribution fitted to each sample tree, and sources of variation in vertical distribution were tested by regressing beta parameter estimates on SNC intensity and other covariates representing tree, stand, and site attributes. Distribution of foliage mass by age-class and by relative height in the crown was significantly affected by SNC severity, in addition to other covariates such as crown size and tree social position. SNC caused a reduction in the amount of foliage in each age-class and greater relative representation of younger needles. SNC also shifted the mode of relative vertical distribution toward the top of the tree for the three youngest foliage age-classes, but toward the base of the crown for 4- and 5-year-old foliage. Quantification of foliage age-class structure and vertical distribution across a range of SNC severity has helped to establish diagnostic criteria for assessing changes in crown structure that precede declines in growth and vigor. The induced changes in crown structure will also help to identify the relative contribution of several mechanisms causing growth losses in diseased trees.

Growth response of young, thinned Douglas-fir stands to nitrogen fertilizer in relation to soil properties and tree nutrition

1994 ◽  
Vol 24 (8) ◽  
pp. 1684-1688 ◽  
Author(s):  
P. Hopmans ◽  
H.N. Chappell
Keyword(s):  
Basal Area ◽  
N Fertilization ◽  
Douglas Fir ◽  
Relative Volume ◽  
Strongly Correlated ◽  
Growth Responses ◽  
Total N ◽  
Soil Variables ◽  
Volume Increment ◽  
Area And Volume

Application of 224 kg N/ha to young, thinned stands of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) at 35 sites in western Oregon and Washington significantly increased basal area and volume increment over 8 years following treatment. However, response varied considerably between sites, and relative volume increment exceeded 10% at only 19 of the 35 sites. Response to applied N was evaluated in relation to forest floor and soil variables as well as to levels of N in foliage. Relative responses in basal area and volume were significantly correlated with total N concentration and the C/N ratio of the soil. However, these relationships explained only part (18–22%) of the observed variation in response. In contrast, relative response was strongly correlated with the level of N in the foliage of nonfertilized trees at 11 sites, accounting for 94% of the variation between sites. Use of foliar N data clearly has potential to predict growth responses to N fertilization of young thinned Douglas-fir stands, although further work is needed to test the relationship for a wider range of sites and stands.

Mineralization and immobilization of soil nitrogen in two Douglas-fir stands 15 and 22 years after nitrogen fertilization

1989 ◽  
Vol 19 (6) ◽  
pp. 798-801 ◽  
Author(s):  
Russell H. Strader ◽  
Dan Binkley
Keyword(s):  
Nitrogen Fertilization ◽  
N Fertilization ◽  
Douglas Fir ◽  
Soil Samples ◽  
N Availability ◽  
Microbial Immobilization ◽  
Mineral N ◽  
Net Mineralization ◽  
Infertile Soils

Additions of 15N-labelled ammonium chloride were used to examine the role of microbial immobilization in long-term growth response of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) plantations to nitrogen fertilization. Soil samples were collected in the summer of 1986 from fertilized (448 or 470 kg N/ha) and nonfertilized plots at previously established N fertilization experiments near Shawnigan Lake, British Columbia, and the Wind River Experimental Forest near Carson, Washington. Douglas-fir on these sites were reported to still be responding to N fertilization after 12 and 18 years. Less than 2% of the added 15N was recovered as mineral N after a 14-day laboratory incubation of soil samples from the fertilized and nonfertilized plots. This indicates that gross mineralization could be over 50 times greater than net mineralization in these infertile soils if the remaining 98% of the added 15N was all biologically immobilized. Net mineralization was significantly greater (p ≤ 0.10) in soils from the fertilized plots than in those from the non-fertilized plots at the Wind River site. Though the current differences in N availability did not appear to be related to differences in microbial immobilization, such large rates of immobilization warrant closer scrutiny as a factor in long-term response to fertilization.

Patterns in vertical distribution of foliage in young coastal Douglas-fir

1996 ◽  
Vol 26 (11) ◽  
pp. 1991-2005 ◽  
Author(s):  
Douglas A. Maguire ◽  
William S. Bennett
Keyword(s):  
Vertical Distribution ◽  
Leaf Area ◽  
Stand Structure ◽  
Douglas Fir ◽  
Parameter Estimates ◽  
Relative Height ◽  
Structure Variation ◽  
Sapwood Area ◽  
Forest Stand Structure ◽  
Wide Range

Total amount and vertical distribution of foliage represent important aspects of forest stand structure and its influence on dry matter productivity, forest microclimate, watershed properties, and habitat structure. Variation in foliage distribution was analyzed on trees and plots in a series of even-aged Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stands scheduled for management under a wide range of silvicultural regimes. Branch-level foliage mass and foliage area equations were developed from a sample of 138 branches. These equations were applied to 27 trees on which the diameter and height of all live primary branches were measured, allowing estimation of both the total amount of foliage and its vertical distribution. A β-distribution was fitted to data describing the vertical distribution of foliage on each tree, and the resulting parameter estimates were modelled as functions of tree height, diameter at breast height, crown length, and relative height in the stand. Foliage area distribution tended to be shifted downward relative to foliage mass because of the expected increase in specific leaf area with depth into the crown. Similarly, the relative foliage distribution in terms of both mass and area was shifted downward as the tree became more dominant, or as relative height in the stand increased. In contrast, foliage on trees of similar relative height was shifted upward in response to the lower stand densities imposed by precommercial thinning. On the stand level, relative vertical distribution of foliage in the canopy was more peaked than would be implied by assuming a constant leaf area/sapwood area ratio throughout the composite tree crowns. Between-stand variation in vertical foliage distribution was dictated by differences in stand top height, height to crown base, and number of trees per hectare.

Effects of urea and ammonium nitrate fertilizer on growth of a young thinned and unthinned Douglas-fir stand

1984 ◽  
Vol 14 (6) ◽  
pp. 952-955 ◽  
Author(s):  
H. J. Barclay ◽  
H. Brix
Keyword(s):  
Ammonium Nitrate ◽  
Nitrogen Source ◽  
Nitrogen Fertilizer ◽  
Nitrogen Fertilization ◽  
Tree Mortality ◽  
Height Growth ◽  
Douglas Fir ◽  
Stem Volume ◽  
Volume Response ◽  
Nitrate Fertilizer

The effects of two sources of nitrogen fertilizer applied at rates of 224 and 448 kg N/ha on growth of a thinned and unthinned 24-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand were studied. Ammonium nitrate yielded higher growth of diameter and volume than did urea over a 9-year period, particularly with thinning. Height growth was not affected by nitrogen source. The efficiency of nitrogen fertilization in terms of stem volume response per kilogram of nitrogen applied was greatest with ammonium nitrate in thinned plots. Tree mortality increased substantially with level of fertilization for both sources, and decreased markedly with thinning.

Late-rotation nitrogen fertilization of Douglas-fir: growth response and fibre properties

2017 ◽  
Vol 47 (1) ◽  
pp. 134-138 ◽  
Author(s):  
Cosmin N. Filipescu ◽  
John A. (Tony) Trofymow ◽  
Ross S. Koppenaal
Keyword(s):  
Nitrogen Fertilization ◽  
Growth Response ◽  
Negative Impact ◽  
Management Practice ◽  
Wood Quality ◽  
Fibre Length ◽  
Douglas Fir ◽  
Stem Volume ◽  
Fibre Properties ◽  
The Impact

Late-rotation fertilization of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) 5 to 10 years before harvesting is a common management practice in British Columbia and the US Pacific Northwest. Despite widespread operational application, knowledge on the impact of late-rotation fertilization on forests, especially fibre properties, is lacking. In this study, we evaluate the growth response and fibre properties following nitrogen fertilization in a productive second-growth coastal Douglas-fir site at age 57 years. Destructive sampling of dominant and co-dominant trees in fertilized and control plots 5 years after fertilization indicated significant gain in stem volume (30%–40%) that was uniformly distributed along the stem. There were no discernible effects on wood quality at the log level in terms of resonance acoustic velocity. However, fibre properties within breast height tree rings indicated significant reductions of ring wood density (by 8%), earlywood density (17%), latewood percentage (10%), and modulus of elasticity (8%). Tracheid dimensions declined in earlywood (reduction of wall thickness by 15%), latewood (radial diameter by 8%), and fibre length (by 6%). Results indicate that late-rotation nitrogen fertilization of Douglas-fir may lead to a significant growth response with only minimal reduction of fibre properties. It is possible that the negative impact on fibre properties could become more significant for repeated applications or higher rates of nitrogen fertilization.

Competitive interactions of whiteleaf manzanita, herbs, Douglas-fir, and ponderosa pine in southwest Oregon

1989 ◽  
Vol 19 (2) ◽  
pp. 232-238 ◽  
Author(s):  
Diane E. White ◽  
Michael Newton
Keyword(s):  
Leaf Area ◽  
Ponderosa Pine ◽  
Canopy Cover ◽  
Douglas Fir ◽  
Stem Volume ◽  
Density Level ◽  
Mixed Stands ◽  
Area Index ◽  
Basal Diameter ◽  
Canopy Volume

Whiteleaf manzanita (Arctostaphylosviscida Parry) was established on three sites at densities ranging from 0 to 27 000 seedlings/ha in 2-year-old mixed stands of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and ponderosa pine (Pinusponderosa Dougl. ex Laws.). Invading herbs were controlled by spraying all plots, except one at each site at the 13 500 manzanita/ha density level. Intraspecific manzanita competition reduced individual shrub basal diameter, leaf area, biomass, and canopy volume by the 3rd year of our study. In contrast, these variables increased at the highest density in the manzanita stand. Stem volume of 5-year-old conifers was reduced in relation to manzanita density, biomass, leaf area index, and canopy cover. The presence of herbaceous vegetation reduced both manzanita and conifer growth by the 3rd year.

Effects of high levels of fertilization with urea on growth of thinned and unthinned Douglas-fir stands

1985 ◽  
Vol 15 (4) ◽  
pp. 730-733 ◽  
Author(s):  
H. J. Barclay ◽  
H. Brix
Keyword(s):  
Volume Growth ◽  
Basal Area ◽  
Douglas Fir ◽  
Stem Volume ◽  
Growth Responses ◽  
Positive Interaction ◽  
Fertilizer Use ◽  
Response Period ◽  
Volume Response ◽  
Fertilizer Rates

The diameter and volume growth of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) were documented 9 years after thinning and fertilization. The treatments involved three levels of thinning (0, 1/3, and 2/3 of basal area removed) and six levels of fertilization (0–1344 kg N/ha) with urea. Increments for both diameter and gross volume increased with the rate of fertilization and responses were still apparent 9 years after treatment. For unthinned plots, the 9-year volume growth responses were 30, 50, and 80% with fertilizer rates of 224, 448, and 896 kg N/ha, respectively. The efficiency of fertilizer use, measured as stem volume response per unit of nitrogen applied, decreased with the rate of fertilization, but this picture may change over a longer response period. There was a positive interaction between fertilization and thinning such that high levels of both mutually enhanced growth. Mortality increased with fertilization, but only noticeably in unthinned plots.

Predicting branch diameters on second-growth Douglas-fir from tree-level descriptors

1999 ◽  
Vol 29 (12) ◽  
pp. 1829-1840 ◽  
Author(s):  
Douglas A Maguire ◽  
Stuart R Johnston ◽  
James Cahill
Keyword(s):  
Stand Density ◽  
Douglas Fir ◽  
Tree Level ◽  
Basal Diameter ◽  
Tree Diameter ◽  
Crown Length ◽  
Second Growth ◽  
Regression Techniques ◽  
Branch Size

The quality of lumber and veneer recovered from logs of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) is directly influenced by the maximum limb size attained on the crop tree. Because limb sizes are influenced by stand-density regimes, a need has arisen for quantitative tools that link a wide array of silvicultural regimes to wood-product quality by accounting for silvicultural effects on crown development. An equation for estimating maximum branch size at a given level within the live crown was developed from data collected on 96 felled sample trees in the Coast Ranges and Cascade foothills of Oregon and Washington. Height and basal diameter of the largest branch within each live whorl were measured on each felled tree, and a predictive equation was developed by various regression techniques. The final mixed-effects nonlinear model estimates maximum branch size as a function of depth into crown and tree diameter at breast height, height, and live crown length.

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