Canadian Forest Service Publications
Evaluation of whole tree growth increment derived from tree-ring series for use in assessments of changes in forest productivity across various spatial scales. 2016. Metsaranta, J.M.; Bhatti, B.S. Forests 7(12):303.
Issued by: Northern Forestry Centre
Catalog ID: 39480
Availability: PDF (download)
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The inherent predictability of inter-annual variation in forest productivity remains unknown. Available field-based data sources for understanding this variability differ in their spatial resolution, temporal resolution, and typical units of measure. Nearly all other tree and forest characteristics are in practice derived from measurements of diameter at breast height (DBH). Therefore, diameter increment reconstructed annually from tree-ring data can be used to estimate annual growth increments of wood volume, but the accuracy and precision of these estimates requires assessment. Annual growth estimates for n = 170 trees sampled for whole stem analysis from five tree species (jack pine, lodgepole pine, black spruce, white spruce, and trembling aspen) in Western Canada were compared against increments derived from breast height measurements only. Inter-annual variability of breast height and whole tree growth increments was highly correlated for most trees. Relative errors varied by species, diameter class, and the equation used to estimate volume (regional vs. national). A simple example of the possible effect of this error when propagated to the stand level is provided.
Plain Language Summary
Changes in climate and other environmental conditions can cause annual forest growth to deviate from its long-term historic average. To make appropriate management plans and to produce accurate reports of a forest’s carbon stocks, forest managers need to know how much tree growth and the capacity of the forest to store carbon through photosynthesis change from year to year. Presently, the best method for obtaining this information is full stem analysis, a labour-intensive process that involves felling and sectioning tree stems at regular intervals. The authors of this study compared the accuracy of full stem analysis with the accuracy of analysis that uses only measurements of tree diameter at breast height reconstructed from tree-ring widths. The results obtained by the two methods were highly correlated for most of the trees in the study. Diameter at breast height is commonly measured in the field and is already widely used to assess tree and forest characteristics. The results of this study show that this information, when derived from tree-ring analysis, can also be used to estimate annual growth.