Influence of Neighbors on Tree Form: Effects of Lateral Shade and Prevention of Sway on the Allometry of Liquidambar Styraciflua (Sweet Gum)

Abstract

Liquidambar styraciflua (sweet gum) saplings were open grown (control), guy‐wired to prevent wind‐induced sway (constrained), or guy‐wired within open‐topped shade cloth cylinders to simulate shading by neighboring trees (shaded). Mechanical stability was assessed after 2 years of growth by field measurement of whole‐tree flexibility and with the critical buckling height predictions of five allometrical models. Data from this experiment are supplemented with measurements of sweet gum trees growing in a 9‐year‐old pine plantation; individuals crowded but not overtopped by pines are compared with similar‐aged trees growing in openings within the plantation. Changes in aboveground architecture were stimulated by both prevention of sway and lateral shade but the effect of the latter was most pronounced; shaded saplings approached or exceeded their calculated critical height and buckled under their own weight when the shade cloth cylinders were removed. Rates of aboveground biomass acquisition, total leaf area, wood density, and wood elastic moduli did not differ among the three treatments; changes in stem allometry accounted for most of the observed differences in tree stability. Sweet gum trees growing in a pine plantation responded similarly to neighbors; crowded trees had larger height: diameter ratios and more closely approached their calculated critical heights than did trees growing in the open. Sweet gum saplings growing in dense stands of similar‐sized plants may surmount their neighbors by allocating relatively more wood to height growth than to girth increment.

Stump Sprout Characteristics of Three Commercial Tree Species in Suriname

“…Dicorynia was the most prolific sprouter, with up to 60 on a single stump, but even Qualea, the least prolific sprouter, averaged nearly 6 per stump. Unexpectedly, sprout density did not vary with stump diameter in any of the species, but at least in Dicorynia, the length of the tallest sprout increased with sprout density, which suggests inter-sprout competition or perhaps a thigmomorphogenic response to crowding [22]. This contention is supported by the positive relationship between sprout height:diameter ratio and sprout density in Dicorynia and Eperua (but not Qualea).…”

Flax (Linum usitatissimum L.) Fibers for Composite Reinforcement: Exploring the Link Between Plant Growth, Cell Walls Development, and Fiber Properties

“…It highlights that, for given material properties, the decrease of the stem diameter reduces the maximum height that a stem can attain before failure. In addition, the critical buckling height depends on other parameters defining the proportionally constant K ; these parameters are the distribution of diameters (i.e., the tapering) and the distribution of mass along the stem, as well as the gradients in mechanical properties along the stem (Holbrook and Putz, 1989; Jaouen et al, 2007). Finally, the safety factor can be defined; it is the ratio between the critical buckling height and the actual height of the plant (Niklas, 1993b, 1994).…”

“…In conclusion, higher density-specific stiffness (E/ρ) are required to decrease the plant vulnerability to buckling (Niklas, 1993a). Nevertheless, the density-specific stiffness precise values, as well as the proportionality constant, are difficult to predict; of course, they differ between plant species (Niklas, 1998), but they also vary as a function of stem development and growth too (Holbrook and Putz, 1989).…”

Fire, fragmentation, and windstorms: A recipe for tropical forest degradation

“…Firstly, forest clearing for pasture and cropping changes local convective circulation patterns and results in strong advective winds near forest edges (Bull & Reynolds, 1968;Durieux, Machado, & Laurent, 2003;Jiao-jun, Xiu-fen, Yutaka, & Takeshi, 2004;Mahmood et al, 2014;Weaver & Avissar, 2001), increasing overall wind stresses on trees near edges (Bull & Reynolds, 1968). Secondly, large trees exposed along recently created forest edges have few adaptations to resist strong winds (Holbrook & Putz, 1989). Thus, windstorms are expected to be most damaging to trees growing along edges of recently cleared fields (Laurance & Curran, 2008).…”