Relating leaf traits to seedling performance in a tropical forest: building a hierarchical functional framework

Abstract

Trait‐based approaches have been extensively used in community ecology to provide a mechanistic understanding of the drivers of community assembly. However, a foundational assumption of the trait framework, traits relate to performance, has been mainly examined through univariate relationships that simplify the complex phenotypic integration of organisms. We evaluate a conceptual framework in which traits are organized hierarchically combining trait information at the individual‐ and species‐level from biomass allocation and organ‐level traits. We focus on photosynthetic traits and predict that the positive effects of increasing plant leaf mass on growth depend on species‐level leaf traits. We modeled growth data on more than 1,500 seedlings from 97 seedling species from a tropical forest in China. We found that seedling growth increases with allocation to leaves (high leaf area ratio and leaf mass fraction) and this effect is accentuated for species with high specific leaf area and leaf area. Also, we found that light has a significant effect on growth, and this effect is additive with leaf allocation traits. Our work offers an approach to gain further understanding of the effects of traits on the whole plant‐level growth via a hierarchical framework including organ‐level and biomass allocation traits at species and individual levels.

Tree growth increases through opposing above‐ground and below‐ground resource strategies

“…The low predictive power of traits may result from examining the effects of only a single leaf trait (e.g. Gibert et al., 2016; Paine et al., 2015) or root trait (Comas et al., 2002; Comas & Eissenstat, 2004) because such univariate or single‐organ trait relationships with growth do not account for the relationships among traits that may strongly influence plant growth or survival (Laughlin & Messier, 2015) and may be too simplistic to represent the functional integration of multiple traits at the whole‐tree level (Marks & Lechowicz, 2006; Umaña et al., in press; Weemstra et al., 2020). Alternately, relationships between leaf and/or root traits individually may be contingent on specific environmental conditions and may not be useful for predicting growth in varying environmental conditions.…”

Bornean tropical forests recovering from logging at risk of regeneration failure

“…Active restoration via rehabilitative silvicultural treatments can accelerate canopy closure (Gourlet‐Fleury et al., 2013; Mills et al., 2019; Osuri et al., 2019; Philipson et al., 2020) and reduce understorey light availability, mirrored by our own finding of lower median canopy gap fractions in AR than in NR or UL forest. Greater competition for light may accelerate investment in shoots to gain access to light in the more shaded understorey environments of AR forests (Umaña et al., 2020, 2021). Seedlings in AR forests also had more acquisitive traits (lower leaf thickness, lower LFP, higher SMRL and higher leaf P, K and Mg concentrations) than those in UL forest, which likely reflects the functional composition of species planted in AR forests.…”

“…Shifts in restoration practices towards planting with more diverse mixtures within and between species could enhance adaptive capacity and help overcome high mortality rates and accelerate the recovery of logged ecosystems (Veryard et al, 2023). Umaña et al, 2020Umaña et al, , 2021Waring & Powers, 2017;Wurzburger & Wright, 2015). Logging of the largest trees in tropical forests reduced canopy leaf cover by >50% and increased understorey light availability at our study site 23-28 years after logging (7 years before this study; Milodowski et al, 2021).…”

“…Active restoration via rehabilitative silvicultural treatments can accelerate canopy closure (Gourlet-Fleury et al, 2013;Mills et al, 2019;Osuri et al, 2019;Philipson et al, 2020) and reduce understorey light availability, mirrored by our own finding of lower median canopy gap fractions in AR than in NR or UL forest. Greater competition for light may accelerate investment in shoots to gain access to light in the more shaded understorey environments of AR forests (Umaña et al, 2020(Umaña et al, , 2021.…”

Heteroblastic Foliage Affects the Accumulation of Non-Structural Carbohydrates and Biomass in Pinus massoniana (Lamb.) Seedlings

“…The free shoot growth and biomass allocation patterns in seedlings have been known as fundamental features of life-history diversification in forest trees [26]. Leaf economics reveal the relationship between leaf function and either the growth potential or cost of morphological constructions, and seedlings can be categorized as having low photosynthetic rates and slow turnovers of dry matter or having high photosynthetic rates and rapid returns [27]. Optimal partitioning theory (OPT) accounts for the allocation of biomass in seedlings to organs with limited resources.…”