Response of Douglas-fir stem profile to operational nitrogen fertilization in western Oregon

2021 ◽  
Vol 496 ◽  
pp. 119411
Author(s):  
Jacob D. Putney ◽  
Douglas A. Maguire
Keyword(s):  
Nitrogen Fertilization ◽  
Douglas Fir

Effects of mechanical stimulus, shade, and nitrogen fertilization on morphology and bending resistance in Douglas-fir seedlings

2003 ◽  
Vol 33 (9) ◽  
pp. 1602-1609 ◽  
Author(s):  
Stephen J Mitchell
Keyword(s):  
Nitrogen Fertilization ◽  
Mechanical Stimulus ◽  
Douglas Fir ◽  
Height Increment ◽  
Stem Form ◽  
Diameter Increment ◽  
Reduced Height ◽  
Bending Resistance ◽  
Volume Increment ◽  
Bending Stresses

Three-year-old coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were planted in a factorial experiment with three levels of shading (0, 30, and 60%), three levels of mechanical stimulus (staked, freestanding, and bent), and two levels of nitrogen fertilization (0 and 200 kg/ha) to investigate the separate and combined effects of these factors on morphology and bending resistance. Fertilization increased branch angle and increased the sensitivity of branch and leader extension to bending stresses but did not affect volume increment, stem form, or bending resistance. The effects of shading and mechanical treatments on morphology were independent and additive. Shading reduced stem diameter and volume increment, but did not affect height increment, producing more slender trees. Bending produced less slender trees through a combination of reduced height increment and increased diameter increment. Staking did not affect tree morphology. Trees under heavy shade were responsive to bending but were more slender and had lower bending resistance than unshaded trees with the same mechanical stimulus. These results point towards the biological basis for the development of tree instability in high density stands.

scholarly journals Survival and Growth of Douglas-Fir Relating to Weeding, Fertilization, and Seed Source

1996 ◽  
Vol 11 (2) ◽  
pp. 62-69 ◽  
Author(s):  
Brian E. Roth ◽  
Michael Newton
Keyword(s):  
Weed Control ◽  
Nitrogen Fertilization ◽  
Seedling Survival ◽  
Seed Orchard ◽  
Douglas Fir ◽  
Seed Source ◽  
Interactive Effects ◽  
Dominant Factor ◽  
Local Source ◽  
Survival And Growth

Abstract The goal of this study was to quantitatively evaluate the individual and interactive effects of weed control, nitrogen fertilization, and seed source on Douglas-fir (Pseudotsuga menziesii) survival and growth in a range of sites and growing conditions in western Oregon. Weed control was the dominant factor influencing seedling survival and growth and accounted for 49% of the explained variation in seedling volume after 2 yr. Nitrogen fertilization had no effect when used in conjunction with weed control and a negative effect when used without weed control. Seedlings from a seed orchard source were significantly larger in diameter and volume than those from a wild local source after two growing seasons, but second-year heights were similar for the two seedling types. Initial seedling size was positively correlated with growth rate. West. J. Appl. For. 11(2):00-00.

Bulldozing stumps and nitrogen fertilization affect growth of Douglas-fir seedlings

1988 ◽  
Vol 18 (6) ◽  
pp. 803-806 ◽  
Author(s):  
W. G. Thies ◽  
E. E. Nelson
Keyword(s):  
Ammonium Nitrate ◽  
Nitrogen Fertilization ◽  
Growing Season ◽  
Douglas Fir ◽  
Olympic Peninsula ◽  
Diameter At Breast Height ◽  
Clear Cut ◽  
Breast Height ◽  
Growing Seasons ◽  
Growth Of Seedlings

Eight treatments involving stump removal by bulldozing in combination with nitrogen fertilization were applied to 0.04-ha circular plots in a clear-cut on the Olympic Peninsula, Washington. Treatments included stump removal (either all stumps removed or the plot left undisturbed) and broadcast fertilization with ammonium nitrate (0, 336, 672, or 1345 kg N ha−1). Diameter at breast height and height of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings, planted several months after treatment, were recorded five and eight seasons after outplanting. The results showed that either bulldozing stumps from the site or fertilizing with ammonium nitrate increased growth of seedlings through their eighth growing season. After eight growing seasons, bulldozing had increased seedling height by 23% and diameter at breast height by 43%; fertilizing produced increases of 13% in height and 17% in diameter at breast height.

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.

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.

Thinning and nitrogen fertilization effects on soil and tree water stress in a Douglas-fir stand

1986 ◽  
Vol 16 (6) ◽  
pp. 1334-1338 ◽  
Author(s):  
H. Brix ◽  
A. K. Mitchell
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Nitrogen Fertilization ◽  
Soil Water Potential ◽  
Early Morning ◽  
Douglas Fir ◽  
Fertilization Effect ◽  
Use Efficiency ◽  
Soil Water Conditions ◽  
Fertilization Effects

Soil and tree water potentials were studied over a 10-year period in a Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand that was treated when 24 years old with different thinning and nitrogen fertilization regimes. Throughout the 10-year period, thinning increased the soil water potential during the dry summer periods (July–September) by as much as 1 MPa both with and without fertilization. Fertilization effect on soil water potential was slight and only apparent in the latter part of the study in spite of large increases in leaf area (50% after 7 years) possibly because of better stomatal control of water loss. Fertilization increased water use efficiency. The favorable soil water conditions produced by thinning led to improved shoot water potential only during predawn and early morning. Removal of understory in a thinned and fertilized plot did not affect soil or shoot water potential.

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