Canadian Forest Service Publications

Occurrence of density-dependent height repression within jack pine and black spruce plantations. 2015. Newton, P. Forests 6:2450-2468.

Year: 2015

Available from: Great Lakes Forestry Centre

Catalog ID: 36566

Language: English

CFS Availability: PDF (download)

Available from the Journal's Web site.
DOI: 10.3390/f6072450

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Abstract

The objective of this study was to investigate the occurrence of density-dependent height relationships in jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) B.S.P.) populations. After assessing and ruling out the presence of consequential spatial correlation effects, the analysis consisted of analyzing the relationship between mean dominant height and initial planting density within 28 Nelder plots located in the central portion of the Canadian Boreal Forest Region. Employing remeasurement data obtained at periodic intervals (16, 20 and 40–41 years post-establishment) across a stand density gradient ranging from a minimum of 1425 stems/ha to a maximum of 28,621 stems/ha, graphical and simple linear regression analyses were used to quantify the stand height–density relationship by species, plot and measurement year. The results indicated the presence of density-dependent effects on height development for both species: 65% of the 83 jack pine relationships and 89% of the 27 black spruce relationships had significant (p ≤ 0.05) and negative slope values. In regards to jack pine for which the data permitted, the occurrence and magnitude of the observed height repression effect increased over time. The asymptotic height repression effect for jack pine was 24% greater than that for black spruce. The results are discussed within the context of the applicability of the density-independent height growth assumption and potential implications for site quality estimation and thinning response modeling.

Plain Language Summary

The objective of this study was to determine if height growth within jack pine and black spruce stand was affected by stand density. Using remeasurements obtained from field plots located in northern Ontario, the statistical relationship between height and density was determined. The results indicated the height development of both species was affected by stand density. The implications of these results within the context of site quality estimation and modeling thinning responses is discussed.

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