Architecture of Iberian canopy tree species in relation to wood density, shade tolerance and climate

Abstract

Tree architecture has important consequences for tree performance as it determines resource capture, mechanical stability and dominance over competitors. We analyzed architectural relationships between stem and crown dimensions for 13 dominant Iberian canopy tree species belonging to the Pinaceae (six Pinus species) and Fagaceae (six Quercus species and Fagus sylvatica) and related these architectural traits to wood density, shade tolerance and climatic factors. Fagaceae had, compared with Pinaceae, denser wood, saplings with wider crowns and adults with larger maximal crown size but smaller maximal height. In combination, these traits enhance light acquisition and persistence in shaded environments; thus, contributing to their shade tolerance. Pinaceae species, in contrast, had low-density wood, allocate more resources to the formation of the central trunk rather than to branches and attained taller maximal heights, allowing them to grow rapidly in height and compete for light following disturbances; thus, contributing to their high light requirements. Wood density had a strong relationship with tree architecture, with dense-wooded species having smaller maximum height and wider crowns, probably because of cheaper expansion costs for producing biomechanically stable branches. Species from arid environments had shorter stems and shallower crowns for a given stem diameter, probably to reduce hydraulic path length and assure water transport. Wood density is an important correlate of variation in tree architecture between species and the two dominant families, with potentially large implications for their resource foraging strategies and successional dynamics.

Changes in structural heterogeneity and stand productivity by mixing Scots pine and Maritime pine

“…In experimental trials with seedlings, Scots pine was able to grow in low light conditions (Gaudio et al, 2011) due to increased total carotenoid concentration and higher ratios of chlorophyll in response to shade than Maritime pine (Sánchez-Gómez et al, 2006). Although the two studied species are rather similar in many traits, the combination of higher crown plasticity in Maritime pine (Vizcaíno-Palomar et al, 2016), slight differences in shade tolerance between species (Poorter et al, 2012), and the higher physiological plasticity of Scots pine (Gaudio et al, 2011;Sánchez-Gómez et al, 2006) allow both species to develop a multi-layered vertical structure and complementary crown architectures when mixed. Thus, intercepted light can also be used more efficiently, suggesting that light-related interactions may contribute to the mixing effect on stand productivity.…”

“…Riofrío et al, (2017b) identified large-scale positive interactions between these species when they coexist in mixtures, and suggested that light competition is the main driver limiting growth. These species show similar crown architecture (Poorter et al, 2012) and slight differences in shade tolerance (Gaudio et al, 2011;Sánchez-Gómez et al, 2006), thus slight or null mixing effects could be expected.…”

Biomass Equations for Tropical Forest Tree Species in Mozambique

“…Umbila presented lowest basic density (0.636 g cm −3 ) and Jambire the highest (0.841 g cm −3 ). Variation among species in the density of their wood is closely related to variation in light demand [71,72]. Miombo species are semi-light demanding Geldenhuys and Goldings [60].…”

Hierarchical Segmentation Framework for Identifying Natural Vegetation: A Case Study of the Tehachapi Mountains, California

“…Tree density distributions, which reflected specific ecological site factors, were more appropriate for occurrence of specific species association (e.g., shade-intolerant species and shade-tolerant species) [42][43][44][45]. In theory, shade-intolerant species tend to occur at sparse tree stands, while shade-tolerant species tend to occur at dense tree stands.…”

“…Identifying tree-density patterns will be used to simplify species association in a given area where there was no recent disturbance. This hypothesis was based on assumptions that shade tolerance was related to variations in tree architectural parameters, such as stem and crown dimensions [42][43][44][45], and species life history traits (e.g., different seedling time between oaks and pines) and environmental conditions (e.g., topographic and climatic conditions), which constrained species regenerations, resulting in different species dominances (pine dominance and oak-pine codominance) in stands with different tree densities [64,65].…”