Petiole mechanics, leaf inclination, morphology, and investment in support in relation to light availability in the canopy of Liriodendron tulipifera

Abstract

To determine the role of leaf mechanical properties in altering foliar inclination angles, and the nutrient and carbon costs of specific foliar angle variation patterns along the canopy, leaf structural and biomechanical characteristics, biomass partitioning into support, and foliar nitrogen and carbon concentrations were studied in the temperate deciduous species Liriodendron tulipifera L., which possesses large leaves on long petioles. We used beam theory to model leaf lamina as a uniform load, and estimated both the lamina and petiole flexural stiffness, which characterizes the resistance to bending of foliar elements at a common load and length. Petiole and lamina vertical inclination angles with respect to horizontal increased with increasing average daily integrated photon flux density (Q ). Yet, the light effects on lamina inclination angle were primary determined by the petiole inclination angle. Although the petioles and laminas became longer, and the lamina loads increased with increasing Q, the flexural stiffness of both lamina and petiole increased to compensate for this, such that the lamina vertical displacement was only weakly related to Q . In addition, increases and decreases in the petiole inclination angle with respect to the horizontal effectively reduced the distance of lamina load from the axis of rotation, thereby reducing the bending moments and lamina inclination due to gravity. We demonstrate that large investments, up to 30% of total leaf biomass, in petiole and large veins are necessary to maintain the lamina at a specific position, but also that light has no direct effect on the fractional biomass investment in support. However, we provide evidence that apart from light availability, structural and chemical characteristics of the foliage may also be affected by water stress, magnitude of which scales positively with Q.

A functional analysis of the crown architecture of tropical forest Psychotria species: do species vary in light capture efficiency and consequently in carbon gain and growth?

“…6) but here there may also be tradeoffs. Displacement of the leaf area away from the point of attachment of the petiole increases the moment of force, requiring additional investment in support (Givnish 1986;Niklas 1992;Niinemets and Fleck 2002). Leaves of P. marginata have the greatest displacement of lamina area away from the petiole attachment point, which causes the increased Ea-This species also has a low SLA as compared to the other species (Table 2), which is consistent with a greater investment in support.…”

Desempenho produtivo do agrião d'água cultivado em solo sob telas de sombreamento

“…No segundo ciclo de desenvolvimento, também foi observada a mesma tendência no tamanho das folhas. Isso porque plantas cultivadas sob telas de sombreamento apresentam aumento da área foliar para maior interceptação da luz (Espindola Junior et al, 2009;Oliveira et al, 2011;Otoni et al, 2012;Sales et al, 2014), enquanto plantas expostas ao sol apresentam menores áreas foliares, como defesa à transpiração e à elevação da temperatura (Niinemets & Fleck, 2002). Além disso, Ribeiro et al (2012) apontam que a qualidade e a intensidade da radiação que incide sobre as folhas das plantas também promovem modificações na espessura do mesófilo, dos tecidos vasculares, da epiderme, da cutícula, da densidade e das demais características estomáticas, para tolerância a essas condições.…”

Arquitetura foliar comparativa de Miconia sellowiana (DC.) Naudin (Melastomataceae) em diferentes fitofisionomias no Estado do Paraná, Brasil

“…anteriores (Niinemets & Fleck 2002;Falster & Westoby 2003). A heterogeneidade da luz que atinge as folhas, principalmente nos ambientes florestais estudados, parece ser um elemento importante na variação de ângulos encontrada (Gálvez & Pearcy 2003).…”

“…Não existiram correlações de massa seca foliar e área foliar com o comprimento (r = -0,06, p>0,05; r = 0,01, p>0,05) e diâmetro do pecíolo (r = -0,03, p>0,05; r = 0,07, p>0,05), respectivamente. No entanto, a relação volume de pecíolo e massa especifica foliar é inversamente proporcional, sugerindo que o volume do pecíolo ajusta-se à massa da folha, por unidade de área (Niklas 1996;Niinemets & Fleck 2002). Esta relação é corroborada com a relação positiva entre a área de tecido mecânico e a massa específica foliar.…”