Effects of light on growth, crown architecture, and specific leaf area for naturally established Pinuscontorta var. latifolia and Pseudotsugamenziesii var. glauca saplings

Abstract

We studied growth, crown architecture, and specific leaf area acclimation of a shade-intolerant species, Pinuscontorta Dougl. ex Loud. var. latifolia Engelm., and a moderately shade-tolerant species, Pseudotsugamenziesii var. glauca (Beissn.) Franco, using naturally regenerated saplings along a wide range of light conditions. Study sites were located within a dry-summer, cool-temperate climate represented by the Dry Cool Interior Douglas-fir biogeoclimatic subzone near Williams Lake, British Columbia, Canada. In an open light environment, Pinuscontorta had a greater growth increment in both terminal and lateral shoots than did Pseudotsugamenziesii. With decreasing light availability (i) terminal increment, mean lateral increment, and total lateral increment decreased in both species (although Pinuscontorta reduced lateral growth significantly faster than Pseudotsugamenziesii); (ii) the ratio of mean lateral to terminal increment in Pinuscontorta did not change, but significantly increased in Pseudotsugamenziesii; (iii) the ratio of total lateral to terminal increment in Pinuscontorta decreased, but increased in Pseudotsugamenziesii; and (iv) specific leaf area in both species increased (in Pseudotsugamenziesii, it was always higher and increased marginally faster than in Pinuscontorta). We concluded that the less shade-tolerant Pinuscontorta was less plastic in crown architecture and specific leaf area than the more shade-tolerant Pseudotsugamenziesii.

Juvenile growth and crown morphological plasticity of eastern white pines (Pinus strobus L.) planted along a natural light gradient: Results after six years

“…This seems to suggest that our six-year-old planted saplings were not heavily suppressed by the light gradient found in the understory. Similar effects of a light gradient on growth in situ have been reported for more shade-tolerant conifers (Klinka et al 1992, Parent and Messier 1995, Chen et al 1996. However, shade-tolerant conifers tended to reach maximum growth at lower light levels of approximately 25% PPFD and to have a much reduced height growth at low light levels.…”

Estimation of crown radii and crown projection area from stem size and tree position

“…Only a larger sample provides the possibility to establish dependencies of crown shape on spacing and competition that have been already found in other investigations [5,12,14,32,34]. Further improvements could be based on the finding that in mixed stands spruce radii are generally over and beech radii are underestimated.…”

Sources of within- and between-stand variability in specific leaf area of three ecologically distinct conifer species

“…Consequently, canopy-average SLA is an important parameter in several process-based models of forest growth * Corresponding author: aaron@holoros.com [30] because it or its inverse, leaf mass area (LMA; g cm −2 ), implies leaf photosynthetic capacity [21] and dark respiration rate [33]. Light conditions at the time of foliage formation have generally been regarded as the primary factor influencing SLA in both hardwoods [8,29] and conifers [5,26]. Hence, SLA within a stand generally decreases with increasing foliage age [7,13,17] and with increasing height from the ground [21].…”