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

Abstract:The relationship between acoustic velocity (v d ) and the dynamic modulus of elasticity (m e ), wood density (w d ), microfibril angle, tracheid wall thickness (w t ,), radial and tangential diameters, fibre coarseness (c o ) and specific surface area (s a ), within standing red pine (Pinus resinosa Ait.) trees, was investigated. The data acquisition phase involved 3 basic steps: (1) random selection of 54 sample trees from 2 intensively-managed 80-year-old plantations in central Canada; (2) attainment of cardinal-based v d measurements transecting the breast-height position on each sample tree; and (3) felling, sectioning and obtaining cross-sectional samples from the first 5.3 m sawlog from which Silviscan-based area-weighted mean attribute estimates were determined. The data analysis phase consisted of applying graphical and correlation analyses to specify regression models for each of the 8 attribute-acoustic velocity relationships. Results indicated that viable relationships were obtained for m e , w d , w t , c o and s a based on a set of statistical measures: goodness-of-fit (42%, 14%, 45%, 27% and 43% of the variability explained, respectively), lack-of-fit (unbiasedness) and predictive precision (±12%, ±8%, ±7%, ±8% and ±6% error tolerance intervals, respectively). Non-destructive approaches for estimating the prerequisite w d value when deploying the analytical framework were also empirically evaluated. Collectively, the proposed approach and associated results provide the foundation for the development of a comprehensive and precise end-product segregation strategy for use in red pine management.

Section: Introductionmentioning

confidence: 99%

Acoustic-Based Non-Destructive Estimation of Wood Quality Attributes within Standing Red Pine Trees

Newton

2017

“…The planting of Douglas-fir seedlings in 1949 established the main stand (DF49), with other species coming from natural regeneration after harvesting (1937, 1938, and 1943) and broadcast burning operations (1939 and 1943) [40]. The 2004 stand density index was 998 stems ha −1 and the stand had an estimated site index of 34 m [22]. In January 2007, a late rotation fertilization treatment was applied aerially to a central portion of the study area (Figure 1) at a rate of 200 kg urea N ha −1 , a typical operational practice in this region [22].…”

Section: Study Areamentioning

confidence: 99%

“…The 2004 stand density index was 998 stems ha −1 and the stand had an estimated site index of 34 m [22]. In January 2007, a late rotation fertilization treatment was applied aerially to a central portion of the study area (Figure 1) at a rate of 200 kg urea N ha −1 , a typical operational practice in this region [22].…”

Section: Study Areamentioning

confidence: 99%

Use of Multi-Temporal LiDAR to Quantify Fertilization Effects on Stand Volume and Biomass in Late-Rotation Coastal Douglas-Fir Forests

Kelley

Trofymow

Filipescu

et al. 2021

Self Cite

Forest fertilization is common in coastal British Columbia as a means to increase wood production and potentially enhance carbon sequestration. Generally, the effects of fertilization are determined by measuring sample plots pre- and post-treatment, resulting in fertilization effects being determined for a limited portion of the treatment area. Applications of remote sensing-based enhanced forest inventories have allowed for estimations to expand to the wider forested area. However, these applications have not focused on monitoring the effects of silvicultural treatments. The objective of this research was to examine if a multi-temporal application of the LiDAR area-based method can be used to detect the fertilization effects on volume, biomass, and height in a second-growth Douglas-fir (Pseudotsuga menziesii) stand. The study area on Vancouver Island was fertilized in January 2007, and sample plots were established in 2011. LiDAR acquisitions were made in 2004, prior to fertilization, and in 2008, 2011, and 2016, covering both treated and untreated areas. A total of 29 paired LiDAR blocks, comprised of four 20 m resolution raster cells, were selected on either side of the fertilization boundary for analysis of the effects across several different stand types differing in the percentage of Douglas-fir, site index, and age. Random forest (RF) plot-level models were developed to estimate total stem volume and total stem biomass for each year of LiDAR acquisition using an area-based approach. Plot level results showed an increase in stem volume by 13% fertilized over control from 2005 to 2011, which was similar to a 14% increase in above-ground carbon stocks estimated using a tree-ring stand reconstruction approach. Plot-level RF models showed R2 values of 0.86 (volume) and 0.92 (biomass) with relative cross-validated root mean square errors of 12.5% (volume) and 11.9% (biomass). For both the sample plots and LiDAR blocks, statistical results indicated no significant differences in volume or biomass between treatments. However, significant differences in height increments were detected between treatments in LiDAR blocks. The results from this research highlight the promising potential for the use of enhanced forest inventory methods to rapidly expand the assessment of treatment effects beyond sample plots to the stand, block, or landscape level.

“…Operationally, the acoustic approach to predicting internal fiber attributes within standing trees is increasingly being employed in (1) operational pre-harvest, end-product surveys in order to increase segregation efficiency and profit margins (e.g., [15,16]), and (2) silvicultural experimentation where acoustic velocity is utilized as a surrogate response metric for inferring wood quality (e.g., fertilization [17] and tree improvement [18] studies). Consequently, failure to account for the effect of temperature and moisture variation on acoustic velocity estimates could potentially lead to erroneous end-product forecasts in forest operations or statistical inference when analyzing experimental and survey results.…”

Section: Introductionmentioning

confidence: 99%

Quantifying the Effects of Wood Moisture and Temperature Variation on Time-of-Flight Acoustic Velocity Measures within Standing Red Pine and Jack Pine Trees

Newton

2018

The relationship between the dynamic modulus of elasticity (me) of xylem tissue and acoustic velocity (vd) has been established for a number of commercially-important coniferous species, including red pine (Pinus resinosa Ait.) and jack pine (Pinus banksiana Lamb.). However, vd has been shown to vary systematically with xylem temperature (tx) and moisture (mx) for some species, and hence when the calibrated me–vd relationships are used outside of the range of conditions under which they were parameterized, erroneous predictions may arise. Consequently, the objectives of this study were (1) to investigate the significance of tx and mx effects on vd measurements within standing red pine and jack pine trees, and (2), given (1), to develop correction equations for standardizing vd measurements to referenced tx and mx conditions if warranted. Analytically, based on a temporal replicated sampling design, 26 mature red pine and 36 semi-mature jack pine trees growing in managed plantations located within central Ontario, Canada (Kirkwood Forest, Great Lakes—St. Lawrence Forest Region), were continuously measured for vd, tx, and mx during the spring-to-autumn seasonal periods in 2016 (red pine) and 2017 (jack pine). A total of 6 measurement events per species occurred at approximately 4–8 week intervals in which a total of 624 red pine and 864 jack pine cardinal-specific (north, east, south, and west) breast-height acoustic velocity, xylem temperature, and xylem moisture measurements were obtained: Yielding a total of 156 red pine and 216 jack pine mean tree-based values available for analysis. Over the sampling periods, (1) mean tree xylem temperatures ranged from a minimum of 3 °C to a maximum of 31 °C (mean = 19.2 °C) in red pine and from a minimum of 0 °C to a maximum of 27 °C (mean = 16.5 °C) in jack pine, and (2) mean tree xylem moistures ranged from a minimum 31% to a maximum of 45% (mean = 38.6%) in red pine and from a minimum 25% to a maximum of 50% (mean = 38.8%) in jack pine. Graphical examination of the moisture effect on the vd and tx relationship by tree and species revealed inversely proportional, linear-like trends at lower moisture levels and directly-proportional, linear-like trends at higher moisture levels where the effect was more evident for red pine than for jack pine. In order to describe this multivariate relationship, species-specific, two-level hierarchical, mixed-effects linear models inclusive of random and fixed effects were specified and subsequently parameterized. The first-level model described the tree-specific vd–tx relationship deploying a simple linear regression specification, whereas the second-level model expressed the first-level parameter estimates as a linear function of seasonal mean tree moisture. The resultant statistically-validated, parameterized regression models, for which 64% (red pine) and 90% (jack pine) of the vd variation was explained, indicated that the vd–tx relationship varied systematically with seasonal mean moisture level in red pine but not so in jack pine. More precisely, in red pine, vd declined with increasing tx at lower moisture levels (<38%), but increased with increasing tx at higher moisture levels (>38%). Conversely, although vd declined with increasing tx in jack pine, the relationship was unaffected by changes in seasonal mean tree moisture levels. Consequently, based on the final hierarchical model specifications, correction equations for adjusting observed vd values to standardized temperature (20 °C) and moisture conditions (40% for red pine) were developed for each species. Across the range of temperatures (≈5 °C–30 °C) and mean moisture levels (≈30–45%) examined, these equations generated a mean absolute vd adjustment of approximately 0.12 km/s for red pine and 0.04 km/s for jack pine. However, based on the corresponding relative magnitude of these adjustments which account for the narrow species-specific vd sample ranges observed (0.80 and 0.85 km/s for red pine and jack pine, respectively), the standardization of vd estimates could be of operational significance when acoustic sampling during periods in which xylem temperature and moisture levels approach the extremities of their spring-to-autumn seasonal ranges. Overall, the results of this empirical-based assessment, which confirmed the presence of temperature and moisture induced variation in acoustic velocity measures within standing red pine and jack pine trees, were largely in accordance with expectation. The subsequent provision of species-specific correction functions for adjusting observed vd sample values to corresponding equivalents referenced to standardized temperature and moisture conditions could assist in mitigating the consequences of environmental variability when acoustic sampling.