Search

The ecology of plant species relies on the synchronous functioning of leaves and roots, but few studies have simultaneously examined the community trait dispersion (CTD) patterns of both organs. We measured 16 analogous leaf and root traits on 44 co-occurring woody species in a subtropical forest in southern China, aiming to examine whether leaf and root traits were coordinated, organized into parallel trait axes, exhibited similar CTD, and displayed consistent responses in CTD and community-weighted means of (CWM) traits over environmental gradients. While the first axes of leaf and root trait variation similarly exhibited a fast–slow continuum, leaf traits covered a secondary "carbon economics" axis, contrasting to root traits depicting a collaboration axis reflecting species' mycorrhizal dependency. Analogous leaf and root chemical traits were generally coordinated but less so for morphological traits. At the community level, changes in the CWM of the first axes were generally consistent among organs with more conservative traits found as increasing elevation but not for the second axis. While root traits became thinner and more conservative as soil phosphorus concentration decreased, leaf traits rarely varied. When different trait axes were combined, leaf traits were overdispersed but tended to converge with increased elevation and soil potassium and phosphorus levels, whereas root traits were clustered but tended to diverge along the same gradients. Our study highlights fine filtering of different suites of traits above- and belowground, which in turn might reduce overall niche overlap among species and promote coexistence with diverse functional designs. [ABSTRACT FROM AUTHOR]

Summary: The root economics space (RES) is multidimensional and largely shaped by belowground biotic and abiotic influences. However, how root–fungal symbioses and edaphic fertility drive this complexity remains unclear.Here, we measured absorptive root traits of 112 tree species in temperate and subtropical forests of China, including traits linked to functional differences between arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) hosts.Our data, from known mycorrhizal tree species, revealed a 'fungal‐symbiosis' dimension distinguishing AM from ECM species. This divergence likely resulted from the contrasting mycorrhizal evolutionary development of AM vs ECM associations. Increased root tissue cortical space facilitates AM symbiosis, whereas increased root branching favours ECM symbiosis. Irrespective of mycorrhizal type, a 'root‐lifespan' dimension reflecting aspects of root construction cost and defence was controlled by variation in specific root length and root tissue density, which was fully independent of root nitrogen content. Within this function‐based RES, we observed a substantial covariation of axes with soil phosphorus and nitrate levels, highlighting the role played by these two axes in nutrient acquisition and conservation.Overall, our findings demonstrate the importance of evolved mycorrhizal symbiosis pathway and edaphic fertility in framing the RES, and provide theoretical and mechanistic insights into the complexity of root economics. [ABSTRACT FROM AUTHOR]

Aims: For plants, elemental nutrients are important belowground resources that sustain growth and survival. To understand how tropical plant nutrient status responds to environmental variation, we asked whether concentrations of nutrients in root and leaf tissues track gradients in soil nutrient concentrations and if tissue nutrient concentrations respond independently or in concert to soil nutrient concentrations. Methods: We measured soil nutrient concentrations of rhizosphere soil and root and leaf tissue elemental concentrations of saplings from 14 Angiosperm families in montane tropical forest of Jianfengling, China. Using mixed-effects models, we modeled the nutrient concentration of plant tissues as a function of soil resources. Results: Of fourteen elements measured, seven —nitrogen, boron, phosphorus, potassium, manganese, copper and zinc— increased in concentrations in root and leaf tissues with higher soil nutrient availability; two decreased —aluminum and carbon; three were invariant —magnesium, sulfur, and calcium; and two —sodium and iron— showed contrasting patterns between leaves and roots. Eight elements necessary to leaf physiological function, but also used in root functioning —nitrogen, boron, magnesium phosphorus, sulfur, potassium, calcium, manganese— were more concentrated in leaves than roots. Additionally, most elements showed tradeoffs in concentrations between roots and leaves. Plant lineage (i.e. family) explained very little of the variation about this overall trend. Conclusions: Overall, increases in tissue nutrient concentrations with soil fertility were subtle if present at all. Thus, we conclude that tissue nutrients of juvenile tropical trees have a high degree of elemental homeostasis with local-scale soil nutrient content in Jianfengling. [ABSTRACT FROM AUTHOR]

Summary: Environmental filtering and limiting similarity mechanisms can simultaneously structure community assemblages. However, how they shape the functional and phylogenetic structure of root neighborhoods remains unclear, hindering the understanding of belowground community assembly processes and diversity maintenance.In a 50‐ha plot in a subtropical forest, China, we randomly sampled > 2700 root clusters from 625 soil samples. Focusing on 10 root functional traits measured on 76 woody species, we examined the functional and phylogenetic structure of root neighborhoods and linked their distributions with environmental cues.Functional overdispersion was pervasive among individual root traits (50% of the traits) and accentuated when different traits were combined. Functional clustering (20% of the traits) seemed to be associated with a soil nutrient gradient with thick roots dominating fertile areas whereas thin roots dominated infertile soils. Nevertheless, such traits also were sorted along other environmental cues, showing multidimensional adaptive trait syndromes. Species relatedness also was an important factor defining root neighborhoods, resulting in significant phylogenetic overdispersion.These results suggest that limiting similarity may drive niche differentiation of coexisting species to reduce competition, and that alternative root strategies could be crucial in promoting root neighborhood resource use and species coexistence. [ABSTRACT FROM AUTHOR]