Effects of light availability and tree size on the architecture of assimilative surface in the canopy of Picea abies: variation in needle morphology

Abstract

Needle dimensions, needle surface area, needle dry weight per area (LWA) and needle density (ND, needle weight per volume) were measured in terminal current-year shoots in a natural canopy of variably sized Picea abies (L.) Karst. trees growing along a light gradient. Needle shape was described as a rhomboid. Needle width (D(2)) increased with increasing diffuse site factor, a(d) (relative amount of penetrating diffuse solar radiation), whereas needle thickness (D(1)) remained nearly constant, resulting in an inverse relationship between D(1)/D(2) and a(d) and an increase in the ratio of total (TLA) to projected needle surface area (PLA) with increasing a(d). Because of the variations in needle morphology with respect to light availability, the shoot parameters used in present canopy models are also expected to be light-sensitive, and studies involving shoot morphology should also consider the variability in needle geometry. Needle dimensions and total tree height were not correlated. However, LWA increase with both increasing a(d) and total tree height. When LWA was expressed as the product of ND and needle height (NH, height of the rhomboidal transverse section of a needle), LWA appeared to increase with irradiance, because of changing NH, and with total tree height, because of changing needle density.

Influence of light and competition on crown and shoot morphological parameters of Norway spruce and silver fir saplings

“…These results, while confirming previous observations on the same species [6,24,25,31], indicate no major difference in the plasticity of response to light -at the crown, shoot and needle level -between Norway spruce and silver fir saplings.…”

“…The positive effect of relative irradiance on both TPA/SSA and LMA indicates that, in the shoots developed in relatively high light, intercepted PPFD is spread out over more needle surface -and that their needles have more photosynthetic tissue -than in shoots developed in shade [24,30]. Conversely, in the flatter and more sparsely packed shade shoots less self-shading occurs than in shoots that have developed with more light.…”

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

“…In Norway spruce (Picea abies (L.) Karst. ), SLA was correlated with tree height [28] and diameter [15]. St. Clair [38] indicated that tree size was negatively correlated with SLA in Douglasfir, as larger trees tended to have heavier, thicker needles.…”

Links between tree structure and functional leaf traits in the tropical forest tree Dicorynia guianensis Amshoff (Caesalpiniaceae)

“…Leaf anatomy and morphology, particularly the stomatal density and the shape of the mesophyll air spaces, affect the resistance to gas-exchange and may thus enhance or limit photosynthetic activities [81,84]. Leaf traits are known to change with plant age [37,59]. In some conifer species, Niinemets [57] has observed an increase in the leaf mass per unit area, a decrease in the mass-based leaf nitrogen content and a decrease in the mass-based rates of photosynthesis.…”