Shoot elongation, leaf demography and bud formation in relation to branch position on Larix laricina saplings

Powell, G. R.

doi:10.1007/bf00196020

Cited by 19 publications

(7 citation statements)

References 27 publications

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“…Comparable decreasing shootlength patterns have previously been shown in other spe-cies to be associated with decreasing cone size (Lyons 1956;Powell 1979), and decreasing duration and rate of shoot elongation (Friesner 1943;Ford et al 1987;Powell 1988). By inference, the cone buds on the longest bearing shoots are in the "weakest" lateral-axis positions on those relatively strong shoots, and the cone buds on the shortest bearing shoots are in the "strongest" positions on those relatively weak shoots.…”

Section: Discussionmentioning

confidence: 73%

Patterns of on-shoot positioning of seed cones in relation to shoot length and position in the crowns of young Picea mariana

Caron

Powell

1993

Trees

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Summary. Patterns of distribution of seed cones along the length and around the circumference of shoots were determined for young black spruce [Picea mariana (Mill.) B.S.P.] trees aged 9-17 years. Seed cone production averaged 5, 30, 62, 95, and 112 per tree of ages 9, 11, 13, 15, and 17 years, respectively. Cone distribution was restricted to distal and medial 1-year-old branches at age 9 and spread to distal 3-year-old branches by age 17. Sequentially, shoots of 0-25, 26-100, 101-250, 251-325, and 326-375 mm bore more cones in terminal, distal, medial, proximal, and basal positions along shoots, respectively. The uppermost and longest distal 1-year-old shoots bore most of their cones proximally and medially. On the shortest and innermost proximal order 2 shoots, cones were often terminal. The percentages of cones borne on upper, lower, and each of the two side surfaces of shoots were 31, 22, and 21, respectively, and 5% of the cones were terminal. Cones on lower surfaces were most common on the longest shoots near the apex of trees. Cones on upper surfaces became prevalent downward and outward in the crown. On-shoot positioning therefore varied in a predictable manner with shoot length, and thus with pattern of shoot-length distribution in the crown.

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Section: Discussionmentioning

confidence: 73%

Patterns of on-shoot positioning of seed cones in relation to shoot length and position in the crowns of young Picea mariana

Caron

Powell

1993

Trees

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“…Young, vigorously growing conifer trees generally exhibit excurrent crown form where greater shoot elongation and dry mass production occur in the upper than in the lower crown (Kozlowski and Ward 1961;Ford et al 1987;Powell 1988). For example, in Picea abies (L.) Karst.…”

Section: Hydrostatic Constraints On Morphological Exploitation Of Lightmentioning

confidence: 98%

Hydrostatic constraints on morphological exploitation of light in tall Sequoia sempervirens trees

et al. 2008

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We studied changes in morphological and physiological characteristics of leaves and shoots along a height gradient in Sequoia sempervirens, the tallest tree species on Earth, to investigate whether morphological and physiological acclimation to the vertical light gradient was constrained by hydrostatic limitation in the upper crown. Bulk leaf water potential (Psi) decreased linearly and light availability increased exponentially with increasing height in the crown. During the wet season, Psi was lower in the outer than inner crown. C isotope composition of leaves (delta(13)C) increased with increasing height indicating greater photosynthetic water use efficiency in the upper crown. Leaf and shoot morphology changed continuously with height. In contrast, their relationships with light availability were discontinuous: morphological characteristics did not correspond to increasing light availability above 55-85 m. Mass-based chlorophyll concentration (chl) decreased with increasing height and increasing light availability. In contrast, area-based chl remained constant or increased with increasing height. Mass-based maximum rate of net photosynthesis (P (max)) decreased with increasing height, whereas area-based P (max) reached maximum at 78.4 m and decreased with increasing height thereafter. Mass-based P (max) increased with increasing shoot mass per area (SMA), whereas area-based P (max) was not correlated with SMA in the upper crown. Our results suggest that hydrostatic limitation of morphological development constrains exploitation of light in the upper crown and contributes to reduced photosynthetic rates and, ultimately, reduced height growth at the tops of tall S. sempervirens trees.

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“…The timing of foliage development also varies within individual plants, as has been shown for several coniferous trees (Bonnet-Masimbert 1982, Ford et al 1987, Powell 1988, Fay and Whitham 1990, Quiring 1993, and thus can also influence herbivore distribution and abundance. The influence of intraplant variability in foliage development on herbivore distribution and abundance should be most important to herbivores that depend upon close synchrony between the appearance of new foliage and the initiation of feeding.…”

Section: Introductionmentioning

confidence: 96%

Intratree Variation in Foliage Development Influences the Foraging Strategy of a Caterpillar

Carroll¹,

Quiring²

1994

Ecology

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Zeiraphera canadensis Mut. & Free. (Lepidoptera: Tortricidae) is an early season folivore that feeds exclusively on young foliage of white spruce (Picea glauca (Moench) Voss). Most first-instar larvae are unable to colonize vigorous upper-crown apical buds due to the limited time during which newly burst buds are suitable to young larvae and the distinct acropetal bud development pattern exhibited by white spruce. However, late second-and early third-instar larvae abandon buds from the lower and middle crown and disperse to upper-crown apical buds once they become available for colonization. We carried out a 3-yr field study to test the hypothesis that "acropetal" dispersal by late secondand early third-instar Z. canadensis larvae through the crown of white spruce is an adaptive response to within-plant variability in foliage development.Survival and the size and developmental rate of survivors were highest when larvae developed on apical buds in the upper crown. Smaller buds located more proximally and/ or lower in the crown declined in quality earlier than did the larger buds in the upper crown. Larvae that developed in buds with several conspecifics survived better, were larger, and developed faster than those that developed alone. Intraspecific larval competition was evident only at the highest densities, where the entire apical bud unit was consumed. Individuals allowed to develop for two instars on buds from the lower crown before being transferred acropetally to complete development on apical buds once they became available, always survived better, were larger, and developed faster than nontransferred larvae, irrespective of initial bud position and/or larval density. In addition, acropetal dispersal did not increase the probability of mortality from Formica ants, the most common predators found foraging on young white spruce. Including the costs and benefits associated with competition and predation, the performance of individuals that were restricted to developing within even the highest quality upper-crown apical buds (i.e., alternative strategy) was lower than for individuals that were allowed to feed twice on new foliage (i.e., the observed strategy). Thus, acropetal dispersal increases individual fitness in a heterogeneous environment where the quality and quantity of required plant resources varies spatially and temporally.

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Shoot elongation, leaf demography and bud formation in relation to branch position on Larix laricina saplings

Cited by 19 publications

References 27 publications

Patterns of on-shoot positioning of seed cones in relation to shoot length and position in the crowns of young Picea mariana

Patterns of on-shoot positioning of seed cones in relation to shoot length and position in the crowns of young Picea mariana

Hydrostatic constraints on morphological exploitation of light in tall Sequoia sempervirens trees

Intratree Variation in Foliage Development Influences the Foraging Strategy of a Caterpillar

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