Plants store nonstructural carbohydrates (NSCs) like starch, fructans and soluble sugars to support metabolism, stress tolerance and defence during low photosynthesis, ultimately influencing their growth and longevity. However, the relationship between NSC composition and growth or persistence in wild plants remains unclear. This study explores trade-offs between growth, longevity and NSCs in 201 plant species across diverse climates in the Western USA, spanning 500-4300 m in elevation and 80-1000 mm in precipitation. Annual growth rates and plant ages were derived from the ring widths of semidesert, steppe and alpine herbs and shrubs, along with NSC profiles in their roots and rhizomes. Results showed an inverse relationship between growth and age, with total NSC, starch and fructan levels negatively correlated with growth, supporting the growth-longevity and growth-storage trade-off hypotheses. Conversely, higher growth rates were linked to soluble sugars, suggesting that climate-driven growth limitations alone do not explain increased NSCs. Fructans were positively associated with longevity, especially in long-lived desert shrubs and alpine herbs, underscoring NSCs' active role in survival strategies. These findings challenge the carbon surplus hypothesis, suggesting that plants actively use specific NSCs to balance growth and persistence, with energy-rich sugars promoting growth and osmoprotective fructans enhancing longevity.

• Keywords
• active accumulation, carbon allocation strategies, carbon allocation trade‐offs, longevity, nonstructural carbohydrates, plant growth,
• MeSH
• Fructans metabolism   MeSH
• Plant Roots metabolism   MeSH
• Carbohydrate Metabolism * MeSH
• Climate MeSH
• Plants * metabolism   MeSH
• Starch metabolism   MeSH
• Carbon * metabolism   MeSH
• Plant Development * MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Fructans MeSH
• Starch MeSH
• Carbon * MeSH

BACKGROUND AND AIMS: Mixed forest plantations are increasingly recognized for their role in mitigating the impacts of climate change and enhancing ecosystem resilience. Yet, there remains a significant gap in understanding the early-stage dynamics of species trait diversity and interspecies interactions, particularly in pure deciduous mixtures. This study aims to explore the timing and mechanisms by which trait diversity of deciduous species and competitive interactions influence yield, carbon allocation and space occupation in mixed forests, both above and below ground. METHODS: A forest inventory was conducted in planted monocultures, two-species and four-species mixtures of European Acer, Tilia, Carpinus and Quercus, representing a spectrum from acquisitive to conservative tree species. Effects of competition were assessed with linear mixed-effects models at the level of biomass and space acquisition, including leaf, canopy, stem and fine root traits. KEY RESULTS: Early above-ground growth effects were observed 6 years post-planting, with significant biomass accumulation after 8 years, strongly influenced by species composition. Mixtures, especially with acquisitive species, exhibited above-ground overyielding, 1.5-1.9 times higher than monocultures. Fine roots showed substantial overyielding in high-diversity stands. Biomass allocation was species specific and varied markedly by tree size and the level of diversity and between acquisitive Acer and the more conservative species. No root segregation was found. CONCLUSIONS: Our findings underscore the crucial role of species trait diversity in enhancing productivity in mixed deciduous forest plantations. Allometric changes highlight the need to differentiate between (active) acclimatizations and (passive) tree size-related changes, but illustrate major consequences of competitive interactions for the functional relationship between leaves, stem and roots. This study points towards the significant contributions of both above- and below-ground components to overall productivity of planted mixed-species forests.

• Keywords
• Acer platanoides, Carpinus betulus, Quercus robur, Tilia cordata, Mixed plantations, biomass allocation, canopy, fine roots, interspecific competition, overyielding, plasticity, tree diversity,
• MeSH
• Acer physiology   growth & development   MeSH
• Acclimatization * physiology   MeSH
• Biomass * MeSH
• Species Specificity MeSH
• Quercus physiology   growth & development   MeSH
• Plant Roots physiology   growth & development   MeSH
• Forests * MeSH
• Trees * physiology   growth & development   MeSH
• Publication type
• Journal Article MeSH

In the context of a recent massive increase in research on plant root functions and their impact on the environment, root ecologists currently face many important challenges to keep on generating cutting-edge, meaningful and integrated knowledge. Consideration of the below-ground components in plant and ecosystem studies has been consistently called for in recent decades, but methodology is disparate and sometimes inappropriate. This handbook, based on the collective effort of a large team of experts, will improve trait comparisons across studies and integration of information across databases by providing standardised methods and controlled vocabularies. It is meant to be used not only as starting point by students and scientists who desire working on below-ground ecosystems, but also by experts for consolidating and broadening their views on multiple aspects of root ecology. Beyond the classical compilation of measurement protocols, we have synthesised recommendations from the literature to provide key background knowledge useful for: (1) defining below-ground plant entities and giving keys for their meaningful dissection, classification and naming beyond the classical fine-root vs coarse-root approach; (2) considering the specificity of root research to produce sound laboratory and field data; (3) describing typical, but overlooked steps for studying roots (e.g. root handling, cleaning and storage); and (4) gathering metadata necessary for the interpretation of results and their reuse. Most importantly, all root traits have been introduced with some degree of ecological context that will be a foundation for understanding their ecological meaning, their typical use and uncertainties, and some methodological and conceptual perspectives for future research. Considering all of this, we urge readers not to solely extract protocol recommendations for trait measurements from this work, but to take a moment to read and reflect on the extensive information contained in this broader guide to root ecology, including sections I-VII and the many introductions to each section and root trait description. Finally, it is critical to understand that a major aim of this guide is to help break down barriers between the many subdisciplines of root ecology and ecophysiology, broaden researchers' views on the multiple aspects of root study and create favourable conditions for the inception of comprehensive experiments on the role of roots in plant and ecosystem functioning.

• Keywords
• below-ground ecology, handbook, plant root functions, protocol, root classification, root ecology, root traits, trait measurements,
• MeSH
• Databases, Factual MeSH
• Ecology MeSH
• Ecosystem * MeSH
• Phenotype MeSH
• Plants * MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

Mycorrhizas are known to have a positive impact on plant growth and ability to resist major biotic and abiotic stresses. However, the metabolic alterations underlying mycorrhizal symbiosis are still understudied. By using metabolomics and transcriptomics approaches, cork oak roots colonized by the ectomycorrhizal fungus Pisolithus tinctorius were compared with non-colonized roots. Results show that compounds putatively corresponding to carbohydrates, organic acids, tannins, long-chain fatty acids and monoacylglycerols, were depleted in ectomycorrhizal cork oak colonized roots. Conversely, non-proteogenic amino acids, such as gamma-aminobutyric acid (GABA), and several putative defense-related compounds, including oxylipin-family compounds, terpenoids and B6 vitamers were induced in mycorrhizal roots. Transcriptomic analysis suggests the involvement of GABA in ectomycorrhizal symbiosis through increased synthesis and inhibition of degradation in mycorrhizal roots. Results from this global metabolomics analysis suggest decreases in root metabolites which are common components of exudates, and in compounds related to root external protective layers which could facilitate plant-fungal contact and enhance symbiosis. Root metabolic pathways involved in defense against stress were induced in ectomycorrhizal roots that could be involved in a plant mechanism to avoid uncontrolled growth of the fungal symbiont in the root apoplast. Several of the identified symbiosis-specific metabolites, such as GABA, may help to understand how ectomycorrhizal fungi such as P. tinctorius benefit their host plants.

• MeSH
• Basidiomycota metabolism   MeSH
• Quercus metabolism   microbiology   MeSH
• gamma-Aminobutyric Acid biosynthesis   MeSH
• Plant Roots metabolism   microbiology   MeSH
• Metabolic Networks and Pathways MeSH
• Metabolomics MeSH
• Gene Expression Regulation, Plant MeSH
• Gene Expression Profiling MeSH
• Symbiosis MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• gamma-Aminobutyric Acid MeSH