Canadian Forest Service Publications

Performance of young jack pine trees originating from two different branch angle traits under different intensities of competition. 2000. Larocque, G.R. Annals of Forest Science 57: 635-649.

Year: 2000

Available from: Laurentian Forestry Centre

Catalog ID: 20477

Language: English

CFS Availability: PDF (request by e-mail)

Abstract

The performance of young jack pine (Pinus banksiana Lamb.) trees, originating from seed orchard trees of two different branch angle traits, was examined under different intensities of competition with morphological measures of crown development and growth efficiency measures. Seedlings were planted under a split-plot design at five initial spacings - 0.5 m, 0.75 m, 1.0 m, 1.5 m and 2.0 m -, three blocks, two branching characteristics and four replicates. Relative growth rate for diameter at breast height (dbh) increased by nearly twofold from the closest to the largest spacing. Crown width, crown ratio, needle density ratio and leaf weight ratio decreased significantly with decrease in spacing, which indicated that the efficiency of jack pine crowns to occupy their growing space and the proportion of photosynthesizing biomass relative to respiring biomass were negatively affected by competition. Needle nitrogen concentration decreased with decrease in spacing and was significantly related to leaf weight ratio. Variation with tree size in the ratios of dbh increment to needle biomass and to needle nitrogen content indicated that small trees produced stemwood per unit of photosynthetic tissue and per unit of nitrogen more efficiently that large trees in the absence of severe competition and that this trend was gradually reversed as the intensity of competition increased. Branch angle trait did not constitute a significant advantage for crown development and stem growth.

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