Montane Temperate-Boreal Forests Retain the Leaf Economic Spectrum Despite Intraspecific Variability

Abstract

Trait-based analyses provide powerful tools for developing a generalizable, physiologically grounded understanding of how forest communities are responding to ongoing environmental changes. Key challenges lie in (1) selecting traits that best characterize the ecological performance of species in the community and (2) determining the degree and importance of intraspecific variability in those traits. Recent studies suggest that globally evident trait correlations (trait dimensions), such as the leaf economic spectrum, may be weak or absent at local scales. Moreover, trait-based analyses that utilize a mean value to represent a species may be misleading. Mean trait values are particularly problematic if species trait value rankings change along environmental gradients, resulting in species trait crossover. To assess how plant traits (1) covary at local spatial scales, (2) vary across the dominant environmental gradients, and (3) can be partitioned within and across taxa, we collected data on 9 traits for 13 tree species spanning the montane temperate—boreal forest ecotones of New York and northern New England. The primary dimension of the trait ordination was the leaf economic spectrum, with trait variability among species largely driven by differences between deciduous angiosperms and evergreen gymnosperms. A second dimension was related to variability in nitrogen to phosphorous levels and stem specific density. Levels of intraspecific trait variability differed considerably among traits, and was related to variation in light, climate, and tree developmental stage. However, trait rankings across species were generally conserved across these gradients and there was little evidence of species crossover. The persistence of the leaf economics spectrum in both temperate and high-elevation conifer forests suggests that ecological strategies of tree species are associated with trade-offs between resource acquisition and tolerance, and may be quantified with relatively few traits. Furthermore, the assumption that species may be represented with a single trait value may be warranted for some trait-based analyses provided traits were measured under similar light levels and climate conditions.

Leaf Functional Traits and Relationships with Soil Properties of Zanthoxylum planispinum ‘dintanensis’ in Plantations of Different Ages

“…Leaf stable carbon isotope and leaf water use efficiency were higher in the late stage of growth, indicating a higher water usage efficiency at this stage. Among many functional traits, specific leaf area, leaf thickness, leaf tissue density, and leaf tissue density are the best variables in the classification axis of plant resource utilization [25,26]. Based on these results, considering that the habitat characteristics of plantations are changing rapidly and that the plantation age in this study varies greatly, we attempted to elucidate the changes in ecological resource strategies of Z. planispinum 'dintanensis' to obtain light, temperature, water, air, heat, and soil with plantation age by using leaf economic spectrum.…”

Large-Scale Controls on the Leaf Economic Spectrum of the Overstory Tree Species Metrosideros polymorpha

“…For example, the leaf economic spectrum (LES), which describes how plant traits covary, primarily describes interspecific trait variation [2]. Since the theory was developed, the role of intraspecific variation in the LES has been investigated with conflicting results [4][5][6][7]. For example, intraspecific variation patterns in montane boreal forests were contrary to community-level interspecific patterns that followed the LES [5].…”

“…Since the theory was developed, the role of intraspecific variation in the LES has been investigated with conflicting results [4][5][6][7]. For example, intraspecific variation patterns in montane boreal forests were contrary to community-level interspecific patterns that followed the LES [5]. In contrast, intraspecific variation in temperate rainforests did follow LES and contributed to overall trait variation within the community [4].…”

Functional traits mediate individualistic species‐environment distributions at broad spatial scales while fine‐scale species associations remain unpredictable

“…At broad spatial scales, differential species' responses to environmental variation sort plants from the regional species pool into local communities (Weiher and Keddy, 1999 ; Kraft et al, 2015a ). These differential species distributions along environmental gradients often reflect fitness differences attributable to interspecific variation in physiological tolerances or to context‐dependent competitive differences (Kraft et al, 2015a ; Álvarez‐Yépiz et al, 2017 ; Hecking et al, 2022 ). Morphological and physiological characteristics determine competitive hierarchies within a given environment and mediate species' responses to environmental variation.…”