Stand growth responses after fertilization for thinned lodgepole pine, Douglas-fir, and spruce in forests of interior British Columbia, Canada

Jang, Woongsoon; Eskelson, Bianca N.I.; Montigny, Louise de; Statland, Catherine A. Bealle; Sattler, Derek F.; Ahmed, Suborna

doi:10.1139/cjfr-2019-0188

Cited by 2 publications

(4 citation statements)

References 51 publications

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“…This finding is similar to studies that report infrequent negative responders and non-responders [11,[42][43][44]. After the peak response two years after application, annual growth response decreased gradually in a non-linear fashion (Figure 3), consistent with the previous observation and modelled responses to N application [10].…”

Section: Discussionsupporting

confidence: 91%

“…The response was greatest in years 2 and 3 after application, peaking at 34% three years after application. The index then rapidly decreased, consistent with modelled responses to N application [10]. The ten-year average value of I r from this analysis was 16.0%.…”

Section: Resultssupporting

confidence: 79%

“…More generally, the approach likely deteriorates with a decreasing range of variability in age. This emphasizes the need for the development of statistical models that simultaneously consider the effects of tree age, N application dose, and time since N application as explanatory factors (e.g., Jang et al [10]).…”

Section: Discussionmentioning

confidence: 99%

“…In the absence of monitoring, previous experimental projects with N applications are the primary way to measure tree growth response and improve stand selection criteria. Although experiments have been effective in establishing average responses to N application for several important commercial tree species [5][6][7][8][9][10][11][12][13], additional information about how responses vary with site conditions, stand age, time after application, and repeated application remains unknown. The stand selection criteria, therefore, often remain general in nature.…”

Section: Introductionmentioning

confidence: 99%

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Evaluating Coastal Douglas Fir Growth Responses to Nitrogen Application Using Tree Ring Chronologies

Hember,

Axelson,

Jang

2023

Forests

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Dendrochronology is a technique that can be applied as a retrospective monitoring (RM) approach to evaluate the performance of nutrient application in forest ecosystems. Applying the RM approach across operations lacks experimental controls, which may adversely affect accuracy and precision of estimates due to greater mismatches in stand conditions between treated and untreated plots. To test the rigor of the RM approach, we collected increment cores of coastal Douglas fir (Pseudotsuga menziesii var. menziesii) at eight sites of an experiment where stands were fertilized in 1971. First, we tested the approach under ideal conditions by sampling from treated and untreated plots of the experiment. Second, we tested the approach using newly established surrogate control (SC) plots, which differed in ecological site classification from those of the treated plots to understand how robust the approach was to mismatches in conditions between treated and untreated samples. We hypothesized that detrending ring width would mitigate error in responses to nutrient application resulting from mismatches in site classification. Within the experiment, the approach indicated an average increase of 15% (5% to 26%, p < 0.05) growth response to operational doses of urea. Different responses were found when the analysis relied on SC plots. Detrending low-frequency variation in ring widths eliminated differences in results arising, at least in part, to mismatches in site class. However, it also reduced the growth response using the experimental control plots to 10%. Dendrochronology with detrending shows promise in the ability to mitigate variation introduced by mismatches in ecological site classification that may occur in operational monitoring. Based on these results, we see potential to implement RM with operations to evaluate and optimize stand selection criteria.

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Section: Discussionsupporting

confidence: 91%

Section: Resultssupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluating Coastal Douglas Fir Growth Responses to Nitrogen Application Using Tree Ring Chronologies

Hember,

Axelson,

Jang

2023

Forests

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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

Forests

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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.

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Stand growth responses after fertilization for thinned lodgepole pine, Douglas-fir, and spruce in forests of interior British Columbia, Canada

Cited by 2 publications

References 51 publications

Evaluating Coastal Douglas Fir Growth Responses to Nitrogen Application Using Tree Ring Chronologies

Evaluating Coastal Douglas Fir Growth Responses to Nitrogen Application Using Tree Ring Chronologies

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

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