ABSTRACT Ultramafic soil is a stressful environment for plants, often limiting species richness and productivity. However, some species or populations employ adaptive strategies to inhabit these soils. Root nutrient acquisition, mediated by fine‐root traits, may contribute to survival and growth in ultramafic soils, yet this process is poorly understood. We compared a range of fine‐root traits that have proximal influences on nutrient acquisition, such as exudation rate and specific root length (SRL), in mature trees growing in ultramafic and adjacent brown forest soils in a cool temperate forest. Measurements were performed on two dominant canopy species, Clethra barbinervis and Quercus serrata , that occur in both soils but differ in mycorrhizal association types (arbuscular mycorrhizal and ectomycorrhizal fungi). Both species showed higher fine‐root exudation rates of carbon and low‐molecular‐mass organic acids in ultramafic soil, though root respiration rates were similar between the soils. Fine‐root tissue density was marginally lower in ultramafic soil for both tree species, potentially allowing trees to efficiently explore for soil nutrients. No significant interaction between species and soil type was detected for any traits, indicating that responses of fine‐root traits to ultramafic soil were similar between the two species. Higher root exudation was associated with higher SRL, lower root diameter, and lower tissue density, and was greater at a given SRL or root diameter in ultramafic soil. These results suggest that trees in ultramafic soil develop efficient nutrient‐acquisition strategies through alteration primarily in root exudation, thereby enabling nutrient uptake, growth, and survival in ultramafic soil.
ABSTRACT Serpentine soil mosaics are found in Shikoku, Japan, and many plant species that inhabit these habitats change their morphology and anatomy in response to the soil chemical and physical properties. To clarify commonality and diversity in leaf morphological responses, we reviewed studies on phylogenetically distinct taxa occurring in serpentine areas, including the woody plants Eurya japonica Thunb. var. japonica (Ternstroemiaceae) and Ligustrum japonicum Thunb. (Oleaceae), and the herbaceous plants Adenophora triphylla (Thunb.) A.DC. var. japonica (Regel) H. Hara (Campanulaceae) and Aster hispidus Thunb. var. leptocladus (Makino) Okuyama (Asteraceae). Our review showed that the leaves of plants growing on serpentine soils tended to be smaller, suggesting that leaf growth may be inhibited under serpentine conditions. However, the developmental processes underlying this small‐leaf phenotype differed among taxa: leaf size reduction was associated with (i) reduced epidermal cell number in woody species, (ii) reduced epidermal cell size in Ad. triphylla var. japonica , and (iii) enlarged epidermal cell size in As. hispidus var. leptocladus . Moreover, the low water retention of serpentine soils was reflected in stomatal traits, since woody plants exhibited reduced stomatal size, whereas herbaceous plants exhibited changes in stomatal density. These findings suggest that leaf size reduction represents a common organ‐level response to serpentine environments, whereas the underlying cellular and stomatal responses are diverse among taxa. This review highlights the need for further comparative studies using standardized trait measurements to test whether these patterns represent general leaf syndromes across serpentine regions in Japan.
ABSTRACT Heavy metal contamination is a persistent environmental problem in terrestrial ecosystems, where metals present in soils can enter food chains and affect organisms across multiple trophic levels. In terrestrial systems, heavy metals are transferred from soils to plants and subsequently to phytophagous insects and their predators, yet these pathways have received less integrated attention than aquatic food webs. This issue is especially relevant in naturally metal‐rich environments such as serpentine ecosystems, where elevated concentrations of metals, particularly nickel, strongly shape plant–insect interactions. This review synthesizes current knowledge on the bioaccumulation, trophic transfer, and elimination of heavy metals in terrestrial soil–plant–insect food chains, drawing on evidence from natural ecosystems as well as laboratory and field studies. We examine the behavior of key essential and non‐essential metals (Cd, Zn, Pb, Hg, Cu, and Ni) and highlight how soil properties, plant uptake mechanisms, insect feeding strategies, and detoxification processes regulate metal movement across trophic levels. Particular attention is given to bioaccumulation and biomagnification patterns, as well as to excretion and elimination pathways such as honeydew production and molting that can limit metal transfer to higher consumers. Overall, the review shows that metal transfer is highly species and metal‐specific, leading to changes in trophic interactions, community structure, and ecosystem functioning. Most available studies were conducted in agricultural systems, highlighting the need for more field‐based ecological investigations across natural ecosystems. We conclude by identifying key knowledge gaps and outlining future research directions needed to better predict ecological risks under increasing metal contamination.
ABSTRACT Edaphically extreme substrates, such as serpentine and limestone, impose strong physiological constraints on plants and are frequently associated with resource‐conservative leaf traits and narrow plant endemism. However, it remains unclear how edaphic selection shapes leaf traits and whether these shifts are driven primarily by direct soil‐imposed constraints or indirectly by changes in leaf elemental composition. Here, we examined soil–leaf elemental relationships, leaf functional traits, and CSR strategies (Competitive, Stress‐tolerant, and Ruderal strategy) using piecewise structural equation modeling across 16 populations of five closely related Epimedium taxa distributed on serpentine, limestone, and other substrates in western Japan. Despite marked differences in soil and leaf elemental composition between serpentine and limestone sites, populations on both substrates converged toward resource‐conservative leaf traits, including lower specific leaf area (SLA) and a shift toward thicker leaves and higher leaf dry matter content (LDMC), even after accounting for species identity. Piecewise structural equation modeling revealed two pathways consistent with the proposed hypotheses: A strong direct association between soil elemental composition and leaf trait variation and a weaker indirect association involving leaf elemental composition. Together, our results suggest that edaphic mosaics are linked to convergent resource‐conservative phenotypes through two partly overlapping pathways across serpentine and limestone soils: strong direct associations with leaf functional traits and weaker associations involving leaf elemental composition.
ABSTRACT As the importance of ecosystem functions and services is receiving increasing attention, it is necessary to understand the difference in the functions and services of various ecosystems. Nevertheless, it is difficult to investigate the differences in ecosystem functions and ecosystem services among different forest types, excluding the effect of environmental differences, which is because different forest types in nature grow in different environments. The botanical gardens of Osaka Metropolitan University have a unique study site that exhibits 11 types of Japanese forests for more than 60 years. These 11 forest types are grown under “one” environmental condition in the same botanical garden; therefore, this study site can be considered a “forest types common‐garden experiment,” and hence researchers can explore the differences in ecosystem functions and services, excluding the effect of environmental differences. This large‐scale project was started soon after the establishment of the botanical gardens in 1950, primarily by Dr. Tatsuo Kira, and a tree census has been conducted since 1978 by the staff of the botanical gardens. Here, we report tree census data, including the diameter at breast height of all trunks with > 5 cm diameter and height of the tree, measured at the 11 types of forests, which co nsist of five evergreen forests, three deciduous forests, and three coniferous forests. The Metadata and complete dataset for this abstract are available in MetaCat in JaLTER at https://doi.org/10.20783/DIAS.JLE.96 .
