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This article explores the impact of different types of mycorrhizal symbiosis on the chemical composition of roots and leaves in temperate woody species. The study found that plants associated with ectomycorrhizal (EcM) fungi had slower decomposition rates and exhibited chemical traits that suppress decomposition compared to plants associated with arbuscular mycorrhizal (AM) fungi. The study also suggests that mycorrhizal associations can influence plant defense responses and the abundance of defense-related phenolic compounds. Another study conducted at the University of Minnesota found that different plant-fungus combinations had significant effects on plant growth and chemical composition. However, the results may not be generalizable to other environmental settings. Another study found that mycorrhizal colonization generally improved plant growth and increased nitrogen content, but the effects on lignin and condensed tannins varied depending on the plant species and type of mycorrhizal fungi. The study also found that mycorrhizal colonization had different effects on lignin molecular composition in gymnosperms and angiosperms. Overall, mycorrhizal colonization can influence the chemical traits and lignin composition of plants, but more research is needed to understand the ecological implications. [Extracted from the article]

1. Root respiration is essential for nutrient acquisition. The respiration rate of absorptive roots theoretically relates to the economics of carbon‐nutrient exchange, but its empirical role remains largely unexplored in the trait space defining nutrient uptake strategies. 2. Here, we measured the respiration rates of the distal, non‐woody, absorptive roots of 252 woody and herbaceous species from subtropical and temperate climate zones, including both arbuscular mycorrhizal and ectomycorrhizal fungal hosts. 3. We found a consistent and positive correlation between root respiration rate and specific root length (root length per dry weight), irrespective of growth form, mycorrhizal type and climate zone. Root respiration rate was also positively, but less strongly and less frequently correlated with root nitrogen concentration. Root morphology strongly explained the fast‐slow gradient of root respiration in the root economics space. 4. By quantifying the ratio of arbuscular mycorrhizal fungal DNA copy number and root tissue DNA copy number using qPCR, we found that the morphology‐driven gradient did not explain the full variation in fungal collaboration; thick roots were consistently well colonised, but medium and thin roots displayed a wide range of colonisation intensity. 5. Synthesis: These results advance our understanding of the fundamental trait relationships that underpin the root economics space. Our study also provides a physiological linkage to the frequently measured root morphological traits and relates the root economics space to root‐derived carbon‐nutrient cycling processes. [ABSTRACT FROM AUTHOR]

Mycorrhizas are widespread below‐ground symbioses formed between plant roots and soil fungi. This plant–fungal partnership impacts terrestrial ecosystems by mediating plant performance and biogeochemical processes. The influence of mycorrhizas on plant and ecosystem functioning is ultimately driven by the biological processes that regulate plant–mycorrhizal interactions. Although convergent patterns in morphological and genetic traits of mycorrhizas have been well‐documented and reflect key selection forces that shape the biology of mycorrhizas, generalizable traits of mycorrhizal‐associated root metabolome, which are more intimately linked to plant and ecosystem functioning, remain unexplored.Here, we compared mycorrhizal‐associated metabolome alterations across multiple plant–mycorrhizal fungus combinations. Specifically, we inoculated a phylogenetically diverse set of temperate tree species with either arbuscular mycorrhizal or ectomycorrhizal fungi (the two major mycorrhizal lifestyles). Using comprehensive metabolomics approaches, we then assessed the metabolome in mycorrhizal and non‐mycorrhizal roots and the corresponding leaves.Comparing across multiple plant–mycorrhizal fungus combinations, our data revealed metabolite alterations unique to mycorrhizal lifestyle as well as those common across plant–fungus combinations irrespective of lifestyles. Roots colonized by arbuscular mycorrhizal and ectomycorrhizal fungi accumulated different sets of carbohydrates, reflecting unique carbon allocation strategies for mycorrhizas. Arbuscular mycorrhizal roots accumulated cyclic polyols (e.g. inositols) inaccessible to their fungal partners, suggesting tight regulation of carbon partitioning. Such accumulation did not occur in ectomycorrhizal‐colonized roots, which instead accrued acyclic polyols (e.g. mannitol and arabitol) that were undetected in non‐mycorrhizal roots and likely of fungal origin. Mycorrhizas also altered specialized metabolism, featuring frequent increases in flavan‐3‐ols (e.g. catechins, gallocatechins, and their oligomers) but decreases in flavanols irrespective of mycorrhizal lifestyles, suggesting tactical reconfiguration of specialized metabolites to both facilitate and restrain the symbiont. These characteristic metabolite alterations were largely root specific and were not mirrored in leaves.Synthesis. Using multiple plant–mycorrhizal systems and metabolomics approaches, our study demonstrates that part of the metabolite alterations occurring during root–mycorrhizal interactions were relatively common across plant–mycorrhizal systems, with implications for both carbon partitioning and tissue protection strategies important for successful symbiosis. These generalizable patterns appear robust to the phylogenetic history of host plants and thus may be widespread in land plants. [ABSTRACT FROM AUTHOR]

Fine‐root branching, vertical distribution and morphology together with root growth rate are key dimensions that determine root strategies for belowground resource acquisition. However, few studies have addressed these traits together with coordinated measures of root growth rates, limiting generalizations about how these root traits coordinate among species. We conducted a common garden experiment to examine interspecific variation and coordination among architectural and morphological traits together with vertical distribution and growth rate of fine‐roots (≤ 2 mm in diameter) across 11 temperate shrub species. Across all species, root morphological traits showed only moderate differences among the first three branching orders and changed more dramatically in higher orders. We found that thin‐rooted shrub species had greater branching intensity than thick‐rooted species. Live fine‐root density (length and mass) decreased as an exponential pattern with increasing soil depth while the density of dead fine‐roots remained relatively constant. Patterns of fine‐root growth rates were independent of morphological and architectural traits, but were negatively related to rooting depth. The different root traits and relationships observed suggest diverse strategies for soil resource acquisition among shrub species. A deep root system would be associated with a slow growth rate. In contrast, the rooting depth was largely independent of root architecture and morphology. [ABSTRACT FROM AUTHOR]

1 would adjust (combinations of) these traits whilst keeping the four key RES traits (root N, specific root length, root tissue density and root diameter) constant, it may remain at the same position at the RES, but still display considerable belowground adjustments in their belowground strategies. The establishment of this root economics space - and its four key traits (root diameter, SRL, root tissue density and root nitrogen concentration) - provides novel and important insights into the formation of diverse belowground strategies and hence, species coexistence and community diversity. A second, independent "conservation axis", in turn, separates species with mass-dense (and presumably long-lived) roots that permits long-term resource conservation, from species with roots that are high in nitrogen concentration indicating active root metabolism and fast turnover. For instance, species sampled in different seasons may display different root traits: under adverse conditions, acquisitive, lower-order roots may be shed and only higher order roots (with distinct traits, such as higher root diameter; McCormack et al. 2015) may be sampled, and root traits themselves (like nitrogen concentration) may change over the seasons (Zadworny et al. 2015). [Extracted from the article]

Summary: The effects of plants on the biosphere, atmosphere and geosphere are key determinants of terrestrial ecosystem functioning. However, despite substantial progress made regarding plant belowground components, we are still only beginning to explore the complex relationships between root traits and functions. Drawing on the literature in plant physiology, ecophysiology, ecology, agronomy and soil science, we reviewed 24 aspects of plant and ecosystem functioning and their relationships with a number of root system traits, including aspects of architecture, physiology, morphology, anatomy, chemistry, biomechanics and biotic interactions. Based on this assessment, we critically evaluated the current strengths and gaps in our knowledge, and identify future research challenges in the field of root ecology. Most importantly, we found that belowground traits with the broadest importance in plant and ecosystem functioning are not those most commonly measured. Also, the estimation of trait relative importance for functioning requires us to consider a more comprehensive range of functionally relevant traits from a diverse range of species, across environments and over time series. We also advocate that establishing causal hierarchical links among root traits will provide a hypothesis‐based framework to identify the most parsimonious sets of traits with the strongest links on functions, and to link genotypes to plant and ecosystem functioning. [ABSTRACT FROM AUTHOR]

Keywords: belowground strategy; belowground terrestrial ecology; mycorrhizal fungi; resource acquisition; root traits; roots; trait function; Virtual Issue EN belowground strategy belowground terrestrial ecology mycorrhizal fungi resource acquisition root traits roots trait function Virtual Issue 2097 2103 7 08/19/21 20210915 NES 210915 The belowground world is one of the final frontiers in terrestrial ecology. Linking root traits with fungal traits Belowground plant strategies encompass more than just root traits, and complex plant interactions with the surrounding rhizosphere microbial community - especially mycorrhizal fungi - are important for plant root survival and resource acquisition (Strullu-Derrien I et al i ., 2018). Even after roots die, the decomposition of roots by soil microbial communities is often mediated by root traits and root associations with mycorrhizal fungi, in addition to the surrounding environment (Lin I et al i ., 2020; Jiang I et al i ., 2021). Linking root form with function While assessments of fine-root trait variation are critically important, our ultimate goal is to link root traits with root function and whole-plant strategies. [Extracted from the article]

Harsh environmental conditions affect both leaf structure and root traits. However, shoot growth in high‐latitude systems is predominately under photoperiod control while root growth may occur for as long as thermal conditions are favorable. The different sensitivities of these organs may alter functional relationships above‐ and belowground along environmental gradients. We examined the relationship between absorptive root and foliar traits of Scots pine trees growing in situ along a temperate‐boreal transect and in trees grown in a long‐term common garden at a temperate latitude. We related changes in foliar nitrogen, phosphorus, specific leaf area, needle mass and 13C signatures to geographic trends in absorptive root biomass to better understand patterns of altered tree nutrition and water balance. Increased allocation to absorptive fine roots was associated with greater uptake of soil nutrients and subsequently higher needle nutrient contents in the northern provenances compared with more southern provenances when grown together in a common garden setting. In contrast, the leaf δ13C in northern and southern provenances were similar within the common garden suggesting that higher absorptive root biomass fractions could not adequately increase water supply in warmer climates. These results highlight the importance of allocation within the fine‐root system and its impacts on needle nutrition while also suggesting increasing stomatal limitation of photosynthesis in the context of anticipated climatic changes. [ABSTRACT FROM AUTHOR]

Summary: Whether and how warming alters functional traits of absorptive plant roots remains to be answered across the globe. Tackling this question is crucial to better understanding terrestrial responses to climate change as fine‐root traits drive many ecosystem processes.We carried out a detailed synthesis of fine‐root trait responses to experimental warming by performing a meta‐analysis of 964 paired observations from 177 publications.Warming increased fine‐root biomass, production, respiration and nitrogen concentration as well as decreased root carbon : nitrogen ratio and nonstructural carbohydrates. Warming effects on fine‐root biomass decreased with greater warming magnitude, especially in short‐term experiments. Furthermore, the positive effect of warming on fine‐root biomass was strongest in deeper soil horizons and in colder and drier regions. Total fine‐root length, morphology, mortality, life span and turnover were unresponsive to warming.Our results highlight the significant changes in fine‐root traits in response to warming as well as the importance of warming magnitude and duration in understanding fine‐root responses. These changes have strong implications for global soil carbon stocks in a warmer world associated with increased root‐derived carbon inputs into deeper soil horizons and increases in fine‐root respiration. [ABSTRACT FROM AUTHOR]

Motivation: Trait data are fundamental to the quantitative description of plant form and function. Although root traits capture key dimensions related to plant responses to changing environmental conditions and effects on ecosystem processes, they have rarely been included in large‐scale comparative studies and global models. For instance, root traits remain absent from nearly all studies that define the global spectrum of plant form and function. Thus, to overcome conceptual and methodological roadblocks preventing a widespread integration of root trait data into large‐scale analyses we created the Global Root Trait (GRooT) Database. GRooT provides ready‐to‐use data by combining the expertise of root ecologists with data mobilization and curation. Specifically, we (a) determined a set of core root traits relevant to the description of plant form and function based on an assessment by experts, (b) maximized species coverage through data standardization within and among traits, and (c) implemented data quality checks. Main types of variables contained: GRooT contains 114,222 trait records on 38 continuous root traits. Spatial location and grain: Global coverage with data from arid, continental, polar, temperate and tropical biomes. Data on root traits were derived from experimental studies and field studies. Time period and grain: Data were recorded between 1911 and 2019. Major taxa and level of measurement: GRooT includes root trait data for which taxonomic information is available. Trait records vary in their taxonomic resolution, with subspecies or varieties being the highest and genera the lowest taxonomic resolution available. It contains information for 184 subspecies or varieties, 6,214 species, 1,967 genera and 254 families. Owing to variation in data sources, trait records in the database include both individual observations and mean values. Software format: GRooT includes two csv files. A GitHub repository contains the csv files and a script in R to query the database. [ABSTRACT FROM AUTHOR]

Summary: Fine roots mediate below‐ground resource acquisition, yet understanding of how fine‐root functional traits vary along environmental gradients, within branching orders and across phylogenetic scales remains limited.Morphological and architectural fine‐root traits were measured on individual root orders of 20 oak species (genus Quercus) from divergent climates of origin that were harvested after three growing seasons in a glasshouse. These were then compared with similar measurements obtained from a phylogenetically diverse dataset of woody species from the Fine‐Root Ecology Database (FRED).For the oaks, only precipitation seasonality and growing season moisture availability were correlated to aspects of root diameter and branching. Strong correlations among root diameters and architecture of different branch orders were common, while correlations between diameter and length were weakly negative. By contrast, the FRED dataset showed strong positive correlations between diameter and length and fewer correlations between root diameter and architectural traits.Our findings suggest that seasonal patterns of water availability are more important drivers of root adaptation in oaks than annual averages in precipitation and temperature. Furthermore, contrasting patterns of trait relationships between the oak and FRED datasets suggest that branching patterns are differentially constrained at narrow vs broad phylogenetic scales. [ABSTRACT FROM AUTHOR]

There is ongoing controversy regarding the borderline personality disorder (BPD) diagnosis. Whilst the experiences of people living with BPD have been widely acknowledged, the process of receiving the diagnosis is poorly described. This systematic review aimed to synthesize the existing research exploring people's experiences of receiving a diagnosis of BPD, as well as examining what is considered best practice in the diagnostic delivery process. The findings from 12 qualitative studies were synthesized using thematic analysis, generating two overarching themes: negative and positive experiences of receiving a diagnosis of BPD. These themes were described using the following sub‐themes: the communication of diagnosis and meaning made of it, validity around diagnosis and attitudes of others. Results indicate that there is a substantial difference between a well‐delivered and poorly delivered diagnosis. The diagnostic delivery process is fundamental to how people understand and interpret the BPD diagnosis. The way in which the BPD diagnosis is shared with people can ultimately shape their views about hope for recovery and their subsequent engagement with services. © 2020 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Understanding the effects of global change in terrestrial communities requires an understanding of how limiting resources interact with plant traits to affect productivity. Here, we focus on nitrogen and ask whether plant community nitrogen uptake rate is determined (a) by nitrogen availability alone or (b) by the product of nitrogen availability and fine‐root mass. Surprisingly, this is not empirically resolved. We performed controlled microcosm experiments and reanalyzed published pot experiments and field data to determine the relationship between community‐level nitrogen uptake rate, nitrogen availability, and fine‐root mass for 46 unique combinations of species, nitrogen levels, and growing conditions. We found that plant community nitrogen uptake rate was unaffected by fine‐root mass in 63% of cases and saturated with fine‐root mass in 29% of cases (92% in total). In contrast, plant community nitrogen uptake rate was clearly affected by nitrogen availability. The results support the idea that although plants may over‐proliferate fine roots for individual‐level competition, it comes without an increase in community‐level nitrogen uptake. The results have implications for the mechanisms included in coupled carbon‐nitrogen terrestrial biosphere models (CN‐TBMs) and are consistent with CN‐TBMs that operate above the individual scale and omit fine‐root mass in equations of nitrogen uptake rate but inconsistent with the majority of CN‐TBMs, which operate above the individual scale and include fine‐root mass in equations of nitrogen uptake rate. For the much smaller number of CN‐TBMs that explicitly model individual‐based belowground competition for nitrogen, the results suggest that the relative (not absolute) fine‐root mass of competing individuals should be included in the equations that determine individual‐level nitrogen uptake rates. By providing empirical data to support the assumptions used in CN‐TBMs, we put their global climate change predictions on firmer ground. We performed controlled microcosm experiments and reanalyzed published pot experiments and field data to determine the relationship between community‐level nitrogen uptake rate, nitrogen availability, and fine‐root mass for 46 unique combinations of species, nitrogen levels, and growing conditions. Plant community nitrogen uptake rate was unaffected by fine‐root mass in 63% of cases and saturated with fine‐root mass in 29% of cases. In contrast, plant community nitrogen uptake rate was clearly affected by nitrogen availability. The results support the idea that although plants may over‐proliferate fine roots for individual‐level competition, it comes without an increase in community‐level nitrogen uptake. [ABSTRACT FROM AUTHOR]

Aim: Rising air temperature and changing precipitation patterns already strongly influence forest ecosystems, yet large‐scale patterns of belowground root trait variation and their underlying drivers are poorly understood. Here, we investigated general patterns of root tip adjustments within fine‐root systems and the potential ecological implications of these patterns. Location: Global. Methods: We synthesize key fine‐root traits related to resource acquisition and determined their responses along climate and edaphic gradients. We specifically identified patterns of root tip abundance (number of root tips per dry biomass of fine roots ≤2 mm in diameter), and root tip density (number of root tips per soil volume) among angiosperm and gymnosperm trees to climate, edaphic gradients and stand properties. Results: We found that angiosperm trees, which were more common in warmer, sometimes drier climates with more fertile soil, formed more root tips (higher root tip abundance, root tip density and higher slope of root tip density vs. fine‐root biomass) than gymnosperm trees, which lived in cooler, wetter climates with poor soil. Angiosperm and gymnosperm trees exhibited opposing trends in response to gradients in climate as gymnosperm trees tended to decrease root tip abundance and root tip density but alternatively increase mycorrhizal mycelial biomass with increasing MAT/MAP (ratio of mean annual temperature to mean annual precipitation), while angiosperm trees tended to increase root tip abundance and root tip density with increasing MAT/MAP. However, the individual trends of root tip abundance and root tip density for angiosperm and gymnosperm trees to MAT or MAP were more similar and often non‐significant. Main conclusions: These results suggest disparate carbon or biomass adjustment strategies within gymnosperm and angiosperm tree fine‐root systems along climate gradients. Differences in angiosperm and gymnosperm tree adjustments in their fine‐root systems to changing environments have implications for how these plant groups are likely to perform in different environments and how their responses to future climate change should be modelled. [ABSTRACT FROM AUTHOR]

Plant roots mediate the impacts of environmental change on ecosystems, yet knowledge of root responses to environmental change is limited because few experiments evaluate multiple environmental factors and their interactions. Inferences about root functions are also limited because root length dynamics are rarely measured.Using a 5‐year experiment in a mixed‐grass prairie, we report the responses of root biomass, length and life span to elevated carbon dioxide (CO2), warming, elevated CO2 and warming combined, and irrigation. Root biomass was quantified using soil cores and root length dynamics were assessed using minirhizotrons. By comparing root dynamics with published results for soil resources and above‐ground productivity, we provide mechanistic insights into how climate change might impact grassland ecosystems.In the upper soil layer, 0–15 cm depth, both irrigation and elevated CO2 alone increased total root length by twofold, but irrigation decreased root biomass and elevated CO2 had only small positive effects on root biomass. The large positive effects of irrigation and elevated CO2 alone on total root length were due to increases in both root length production and root life span. The increased total root length and life span under irrigation and elevated CO2 coincided with apparent shifts from water limitation of plant growth to nitrogen limitation. Warming alone had minimal effects on root biomass, length and life span in this shallow soil layer. Warming and elevated CO2 combined increased root biomass and total root length by c. 25%, but total root length in this treatment was lower than expected if the effects of CO2 and warming alone were additive. Treatment effects on total root length and root life span varied with soil depth and root diameter.Synthesis. Sub‐additive effects of CO2 and warming suggest studies of elevated CO2 alone might overestimate the future capacity of grassland root systems to acquire resources. In this mixed‐grass prairie, elevated CO2 with warming stimulated total root length and root life span in deeper soils, likely enhancing plant access to more stable pools of growth‐limiting resources, including water and phosphorus. Thus, these root responses help explain previous observations of higher, and more stable, above‐ground productivity in these projected climate conditions. Sub‐additive effects of CO2 and warming suggest studies of elevated CO2 alone might overestimate the future capacity of grassland root systems to acquire resources. In this mixed‐grass prairie, elevated CO2 with warming stimulated total root length and root life span in deeper soils, likely enhancing plant access to more stable pools of growth‐limiting resources, including water and phosphorus. Thus, these root responses help explain previous observations of higher, and more stable, above‐ground productivity in these projected climate conditions [ABSTRACT FROM AUTHOR]

Abstract: The distribution of mycorrhizal associations across biomes parallels a distinct gradient of soil carbon (C) and nitrogen (N) stocks, raising the question of how mycorrhizal traits relate to ecosystem properties. Arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) hosts and fungi employ contrasting strategies for N acquisition, which may manifest in differences in soil C and N pools and/or soil C:N. However, cross‐biome comparisons are confounded with climatic and edaphic gradients as well as phylogenetic and functional trait distributions of component plant species. Here, we test emerging hypotheses that soil C, N and C:N are related to the dominance of EM trees within a temperate forest region where AM and EM trees largely coexist but vary in local abundance. To determine the importance of mycorrhizal type on soil C and N, we analysed data from c. 1,000 forest inventory plots in the eastern United States. For each plot, we quantified the dominance of trees with different mycorrhizal associations and accounted for potentially confounding variables including phylogeny (angiosperm or gymnosperm), leaf N, soil clay content and climate. We used hierarchical Bayesian models to determine how these variables explained the patterns of soil C and N in the forest floor and mineral soil layers. Increasing EM dominance was associated with higher C:N across all soil layers. This relationship remained even after accounting for tree phylogeny, leaf N content, soil clay content, temperature and precipitation, which were all important for explaining soil C:N. However, this mycorrhizal pattern of soil C:N was not related to increases in soil C content; rather, increasing EM dominance was associated with reductions in soil N. Synthesis. Our findings are consistent with the proposition that mycorrhizal associations are related to terrestrial ecosystem properties. The mycorrhizal effect on soil C:N may result from differences in how arbuscular mycorrhizal and ectomycorrhizal plants interact with their fungal symbionts, decomposers and organic matter, to sustain differential cycling of C and N. Alternatively, these patterns could arise from differential success of the two mycorrhizal types in contrasting soil conditions; both processes may occur simultaneously, leading to a self‐reinforcing positive feedback. [ABSTRACT FROM AUTHOR]

The article presents an update on various research on trait covariances and plant strategies that make up the warp of plant form and function presented at the 39th "New Phytologist" Trait Covariation Symposium held at Exeter, England in June 2017. Topics covered include how trait covariance can identify common dimensions of phenotypic variation, how many common axes of plant strategy exist, and root traits in resource acquisition and conservation.

Functional traits and their variation mediate plant species coexistence and spatial distribution. Yet, how patterns of variation in belowground traits influence resource acquisition across species and plant communities remains obscure., To characterize diverse belowground strategies in relation to species coexistence and abundance, we assessed four key belowground traits - root diameter, root branching intensity, first-order root length and mycorrhizal colonization - in 27 coexisting species from three grassland communities along a precipitation gradient., Species with thinner roots had higher root branching intensity, but shorter first-order root length and consistently low mycorrhizal colonization, whereas species with thicker roots enhanced their capacity for resource acquisition by producing longer first-order roots and maintaining high mycorrhizal colonization. Plant species observed across multiple sites consistently decreased root branching and/or mycorrhizal colonization, but increased lateral root length with decreasing precipitation. Additionally, the degree of intraspecific trait variation was positively correlated with species abundance across the gradient, indicating that high intraspecific trait variation belowground may facilitate greater fitness and chances of survival across multiple habitats., These results suggest that a small set of critical belowground traits can effectively define diverse resource acquisition strategies in different environments and may forecast species survival and range shifts under climate change. [ABSTRACT FROM AUTHOR]

Ecosystem functioning relies heavily on below-ground processes, which are largely regulated by plant fine-roots and their functional traits. However, our knowledge of fine-root trait distribution relies to date on local- and regional-scale studies with limited numbers of species, growth forms and environmental variation., We compiled a world-wide fine-root trait dataset, featuring 1115 species from contrasting climatic areas, phylogeny and growth forms to test a series of hypotheses pertaining to the influence of plant functional types, soil and climate variables, and the degree of manipulation of plant growing conditions on species fine-root trait variation. Most particularly, we tested the competing hypotheses that fine-root traits typical of faster return on investment would be most strongly associated with conditions of limiting versus favourable soil resource availability. We accounted for both data source and species phylogenetic relatedness., We demonstrate that: (i) Climate conditions promoting soil fertility relate negatively to fine-root traits favouring fast soil resource acquisition, with a particularly strong positive effect of temperature on fine-root diameter and negative effect on specific root length ( SRL), and a negative effect of rainfall on root nitrogen concentration; (ii) Soil bulk density strongly influences species fine-root morphology, by favouring thicker, denser fine-roots; (iii) Fine-roots from herbaceous species are on average finer and have higher SRL than those of woody species, and N2-fixing capacity positively relates to root nitrogen; and (iv) Plants growing in pots have higher SRL than those grown in the field., Synthesis. This study reveals both the large variation in fine-root traits encountered globally and the relevance of several key plant functional types and soil and climate variables for explaining a substantial part of this variation. Climate, particularly temperature, and plant functional types were the two strongest predictors of fine-root trait variation. High trait variation occurred at local scales, suggesting that wide-ranging below-ground resource economics strategies are viable within most climatic areas and soil conditions. [ABSTRACT FROM AUTHOR]

Variation and tradeoffs within and among plant traits are increasingly being harnessed by empiricists and modelers to understand and predict ecosystem processes under changing environmental conditions. While fine roots play an important role in ecosystem functioning, fine-root traits are underrepresented in global trait databases. This has hindered efforts to analyze fine-root trait variation and link it with plant function and environmental conditions at a global scale. This Viewpoint addresses the need for a centralized fine-root trait database, and introduces the Fine-Root Ecology Database ( FRED, ) which so far includes > 70 000 observations encompassing a broad range of root traits and also includes associated environmental data. FRED represents a critical step toward improving our understanding of below-ground plant ecology. For example, FRED facilitates the quantification of variation in fine-root traits across root orders, species, biomes, and environmental gradients while also providing a platform for assessments of covariation among root, leaf, and wood traits, the role of fine roots in ecosystem functioning, and the representation of fine roots in terrestrial biosphere models. Continued input of observations into FRED to fill gaps in trait coverage will improve our understanding of changes in fine-root traits across space and time. [ABSTRACT FROM AUTHOR]

Trait-based approaches provide a useful framework to investigate plant strategies for resource acquisition, growth, and competition, as well as plant impacts on ecosystem processes. Despite significant progress capturing trait variation within and among stems and leaves, identification of trait syndromes within fine-root systems and between fine roots and other plant organs is limited. Here we discuss three underappreciated areas where focused measurements of fine-root traits can make significant contributions to ecosystem science. These include assessment of spatiotemporal variation in fine-root traits, integration of mycorrhizal fungi into fine-root-trait frameworks, and the need for improved scaling of traits measured on individual roots to ecosystem-level processes. Progress in each of these areas is providing opportunities to revisit how below-ground processes are represented in terrestrial biosphere models. Targeted measurements of fine-root traits with clear linkages to ecosystem processes and plant responses to environmental change are strongly needed to reduce empirical and model uncertainties. Further identifying how and when suites of root and whole-plant traits are coordinated or decoupled will ultimately provide a powerful tool for modeling plant form and function at local and global scales. [ABSTRACT FROM AUTHOR]

Plant functional traits may be altered as plants adapt to various environmental constraints. Cold, low fertility growing conditions are often associated with root adjustments to increase acquisition of limiting nutrient resources, but they may also result in construction of roots with reduced uptake potential but higher tissue persistence. It is ultimately unclear whether plants produce fine roots of different structure in response to decreasing temperatures and whether these changes represent a trade-off between root function or potential root persistence. We assessed patterns of root construction based on various root morphological, biochemical and defense traits including root diameter, specific root length ( SRL), root tissue density ( RTD), C:N ratio, phenolic compounds, and number of phellem layers across up to 10 root orders in diverse populations of Scots pine along a 2000-km climatic gradient in Europe. Our results showed that different root traits are related to mean annual temperature ( MAT) and expressed a pattern of higher root diameter and lower SRL and RTD in northern sites with lower MAT. Among absorptive roots, we observed a gradual decline in chemical defenses (phenolic compounds) with decreasing MAT. In contrast, decreasing MAT resulted in an increase of structural protection (number of phellem layers) in transport fine roots. This indicated that absorptive roots with high capacity for nutrient uptake, and transport roots with low uptake capacity, were characterized by distinct and contrasting trade-offs. Our observations suggest that diminishing structural and chemical investments into the more distal, absorptive roots in colder climates is consistent with building roots of higher absorptive capacity. At the same time, roots that play a more prominent role in transport of nutrients and water within the root system saw an increase in structural investment, which can increase persistence and reduce long-term costs associated with their frequent replacement. [ABSTRACT FROM AUTHOR]

• Compared with ectomycorrhizal (ECM) forests, arbuscular mycorrhizal (AM) forests are hypothesized to have higher carbon (C) cycling rates and a more open nitrogen (N) cycle. • To test this hypothesis, we synthesized 645 observations, including 22 variables related to below-ground C and N dynamics from 100 sites, where AM and ECM forests co-occurred at the same site. • Leaf litter quality was lower in ECM than in AM trees, leading to greater forest floor C stocks in ECM forests. By contrast, AM forests had significantly higher mineral soil C concentrations, and this result was strongly mediated by plant traits and climate. No significant differences were found between AM and ECM forests in C fluxes and labile C concentrations. Furthermore, inorganic N concentrations, net N mineralization and nitrification rates were all higher in AM than in ECM forests, indicating 'mineral' N economy in AM but 'organic' N economy in ECM trees. • AM and ECM forests show systematic differences in mineral vs organic N cycling, and thus mycorrhizal type may be useful in predicting how different tree species respond to multiple environmental change factors. By contrast, mycorrhizal type alone cannot reliably predict below-ground C dynamics without considering plant traits and climate. [ABSTRACT FROM AUTHOR]

The article reports that arbuscular mycorrhizal (AM), ectomycorrhizal (ECM) and ericoid mycorrhizal (ERM) plants have evolved unique functional traits in response to particular sets of environmental, and especially soil, conditions. The AM habit likely arose at a single time during the early evolution of both plants and fungi. It states that the three major types of mycorrhizal symbioses display an interesting mismatch in the phylogenetic diversity of plants and fungi associated with each.

Patterns of plant biomass allocation and functional adjustments along climatic gradients are poorly understood, particularly belowground. Generally, low temperatures suppress nutrient release and uptake, and forests under such conditions have a greater proportion of their biomass in roots. However, it is not clear whether 'more roots' means better capacity to acquire soil resources., Herein we quantified patterns of fine-root anatomy and their biomass distribution across Scots pine ( Pinus sylvestris) populations both along a 2000-km latitudinal gradient and within a common garden experiment with a similar range of populations., We found that with decreasing mean temperature, a greater percentage of Scots pine root biomass was allocated to roots with higher potential absorptive capacity. Similar results were seen in the common experimental site, where cold-adapted populations produced roots with greater absorptive capacity than populations originating from warmer climates., These results demonstrate that plants growing in or originated from colder climates have more acquisitive roots, a trait that is likely adaptive in the face of the low resource availability typical of cold soils. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi ( AMF) mediate plant interspecific competition and community structure. However, the magnitude and direction of AMF effects and underlying mechanisms are not clear. Here, we synthesized the results of 304 studies to evaluate how AMF affect plant competition and community structure and which abiotic and biotic conditions in experimental design modify these AMF effects., The magnitude and direction of AMF effects on plant competitive ability (in terms of competitive response) differed markedly among plant functional groups. When AMF inoculum was added, competitive ability was strongly enhanced in N-fixing forbs and was significantly suppressed in C3 grasses, whereas no effect was observed in C4 grasses, non-N-fixing forbs and woody species. Furthermore, AMF inoculation increased competitive ability of perennial species when their competitors were annual species., AMF inoculation differentially influenced separate aspects of plant community structure and species composition. AMF inoculation significantly increased plant diversity but had no effects on plant productivity. Response of dominant plant species to AMF inoculation was the determining factor in explaining variations in how and to what degree plant diversity was influenced by AMF inoculation. When dominant species derived strong benefits from AMF, their dominance level was increased by AMF inoculation, which consequently decreased plant diversity. We did not find stronger AMF effects on plant diversity and productivity when greater numbers of AMF species were used in the inoculation., Synthesis. Despite large variations in AMF effects among studies, a unifying mechanism was observed that the mycorrhizal responsiveness (differences in plant growth between AMF and non- AMF colonization treatments) of target and neighbouring plant species can determine AMF effects on the competitive outcome among plant species, which in turn influenced plant species diversity and community composition. Given that plant traits, soil nutrient conditions and probably mycorrhizal fungal traits are all factors determining the degree of mycorrhizal response of plant species, future studies should explicitly consider each of these factors in experimental design to better understand AMF effects on plant coexistence, plant community dynamics and ecosystem processes. [ABSTRACT FROM AUTHOR]

Leaf economics and hydraulic traits are critical to leaf photosynthesis, yet it is debated whether these two sets of traits vary in a fully coordinated manner or there is room for independent variation. Here, we tested the relationship between leaf economics traits, including leaf nitrogen concentration and leaf dry mass per area, and leaf hydraulic traits including stomatal density and vein density in five tropical-subtropical forests. Surprisingly, these two suites of traits were statistically decoupled. This decoupling suggests that independent trait dimensions exist within a leaf, with leaf economics dimension corresponding to light capture and tissue longevity, and the hydraulic dimension to water-use and leaf temperature maintenance. Clearly, leaf economics and hydraulic traits can vary independently, thus allowing for more possible plant trait combinations. Compared with a single trait dimension, multiple trait dimensions may better enable species adaptations to multifarious niche dimensions, promote diverse plant strategies and facilitate species coexistence. [ABSTRACT FROM AUTHOR]

505I.506II.506III.508IV.512V.513VI.514515References515 Summary: Fine roots acquire essential soil resources and mediate biogeochemical cycling in terrestrial ecosystems. Estimates of carbon and nutrient allocation to build and maintain these structures remain uncertain because of the challenges of consistently measuring and interpreting fine‐root systems. Traditionally, fine roots have been defined as all roots ≤ 2 mm in diameter, yet it is now recognized that this approach fails to capture the diversity of form and function observed among fine‐root orders. Here, we demonstrate how order‐based and functional classification frameworks improve our understanding of dynamic root processes in ecosystems dominated by perennial plants. In these frameworks, fine roots are either separated into individual root orders or functionally defined into a shorter‐lived absorptive pool and a longer‐lived transport fine‐root pool. Using these frameworks, we estimate that fine‐root production and turnover represent 22% of terrestrial net primary production globally – a c. 30% reduction from previous estimates assuming a single fine‐root pool. Future work developing tools to rapidly differentiate functional fine‐root classes, explicit incorporation of mycorrhizal fungi into fine‐root studies, and wider adoption of a two‐pool approach to model fine roots provide opportunities to better understand below‐ground processes in the terrestrial biosphere. [ABSTRACT FROM AUTHOR]

While multiple experiments have demonstrated that trees exposed to elevated CO2 can stimulate microbes to release nutrients from soil organic matter, the importance of root- versus mycorrhizal-induced changes in soil processes are presently unknown., We analyzed the contribution of roots and mycorrhizal activities to carbon (C) and nitrogen (N) turnover in a loblolly pine ( Pinus taeda) forest exposed to elevated CO2 by measuring extracellular enzyme activities at soil microsites accessed via root windows. Specifically, we quantified enzyme activity from soil adjacent to root tips (rhizosphere), soil adjacent to hyphal tips (hyphosphere), and bulk soil., During the peak growing season, CO2 enrichment induced a greater increase of N-releasing enzymes in the rhizosphere (215% increase) than in the hyphosphere (36% increase), but a greater increase of recalcitrant C-degrading enzymes in the hyphosphere (118%) than in the rhizosphere (19%). Nitrogen fertilization influenced the magnitude of CO2 effects on enzyme activities in the rhizosphere only. At the ecosystem scale, the rhizosphere accounted for c. 50% and 40% of the total activity of N- and C-releasing enzymes, respectively., Collectively, our results suggest that root exudates may contribute more to accelerated N cycling under elevated CO2 at this site, while mycorrhizal fungi may contribute more to soil C degradation. [ABSTRACT FROM AUTHOR]

The article discusses important themes that came out from the International Symposium on Critical Zone Biochemistry and Belowground Ecological Research held in Beijing, China in May 2014. It emphasizes the importance to identify broad patterns of root and mycorrhizal trait variation in order to forecast variation in function across species and sites. Also, it asserts the role of mycorrhizal fungi and roots in the ecosystem process.

The timing of fine root production and turnover strongly influences both the seasonal potential for soil resource acquisition among competing root systems and the plant fluxes of root carbon into soil pools. However, basic patterns and variability in the rates and timing or fine root production and turnover are generally unknown among perennial plants species. We address this shortfall using a heuristic model relating root phenology to turnover together with three years of minirhizotron observations of root dynamics in 12 temperate tree species grown in a common garden. We specifically investigated how the amount and the timing of root production differ among species and how they impact estimates of fine root turnover. Across the 12 species, there was wide variation in the timing of root production with some species producing a single root flush in early summer and others producing roots either more uniformly over the growing season or in multiple pulses. Additionally, the pattern and timing of root production appeared to be consistent across years for some species but varied in others. Root turnover rate was related to total root production (P < 0.001) as species with greater root production typically had faster root turnover rates. We also found that, within species, annual root production varied up to a threefold increase between years, which led to large interannual differences in turnover rate. Results from the heuristic model indicated that shifting the pattern or timing of root production can impact estimates of root turnover rates for root populations with life spans less than one year while estimates of root turnover rate for longer lived roots were unaffected by changes in root phenology. Overall, we suggest that more detailed observations of root phenology and production will improve fidelity of root turnover estimates. Future efforts should link patterns of root phenology and production with whole-plant life history traits and variation in annual and seasonal climate. [ABSTRACT FROM AUTHOR]

Large-scale, long-term FACE (Free-Air CO2 enrichment) experiments indicate that increases in atmospheric CO2 concentrations will influence forest C cycling in unpredictable ways. It has been recently suggested that responses of mycorrhizal fungi could determine whether forest net primary productivity ( NPP) is increased by elevated CO2 over long time periods and if forests soils will function as sources or sinks of C in the future. We studied the dynamic responses of ectomycorrhizae to N fertilization and atmospheric CO2 enrichment at the Duke FACE experiment using minirhizotrons over a 6 year period (2005-2010). Stimulation of mycorrhizal production by elevated CO2 was observed during only 1 (2007) of 6 years. This increased the standing crop of mycorrhizal tips during 2007 and 2008; during 2008, significantly higher mortality returned standing crop to ambient levels for the remainder of the experiment. It is therefore unlikely that increased production of mycorrhizal tips can explain the lack of progressive nitrogen limitations and associated increases in N uptake observed in CO2-enriched plots at this site. Fertilization generally decreased tree reliance on mycorrhizae as tip production declined with the addition of nitrogen as has been shown in many other studies. Annual NPP of mycorrhizal tips was greatest during years with warm January temperatures and during years with cool spring temperatures. A 2 °C increase in average late spring temperatures (May and June) decreased annual production of mycorrhizal root tip length by 50%. This has important implications for ecosystem function in a warmer world in addition to potential for forest soils to sequester atmospheric C. [ABSTRACT FROM AUTHOR]

Fine root dynamics control a dominant flux of carbon from plants and into soils and mediate potential uptake and cycling of nutrients and water in terrestrial ecosystems. Understanding of these patterns is needed to accurately describe critical processes like productivity and carbon storage from ecosystem to global scales. However, limited observations of root dynamics make it difficult to define and predict patterns of root dynamics across broad spatial scales. Here, we combine species-specific estimates of fine root dynamics with a model that predicts current distribution and future suitable habitat of temperate tree species across the eastern United States ( US). Estimates of fine root lifespan and turnover are based on empirical observations and relationships with fine root and whole-plant traits and apply explicitly to the fine root pool that is relatively short-lived and most active in nutrient and water uptake. Results from the combined model identified patterns of faster root turnover rates in the North Central US and slower turnover rates in the Southeastern US. Portions of Minnesota, Ohio, and Pennsylvania were also predicted to experience >10% increases in root turnover rates given potential shifts in tree species composition under future climate scenarios while root turnover rates in other portions of the eastern US were predicted to decrease. Despite potential regional changes, the average estimates of root lifespan and turnover for the entire study area remained relatively stable between the current and future climate scenarios. Our combined model provides the first empirically based, spatially explicit, and spatially extensive estimates of fine root lifespan and turnover and is a potentially powerful tool allowing researchers to identify reasonable approximations of forest fine root turnover in areas where no direct observations are available. Future efforts should focus on reducing uncertainty in estimates of root dynamics by better understanding how climate and soil factors drive variability in root dynamics of different species. [ABSTRACT FROM AUTHOR]

Although linkages of leaf and whole-plant traits to leaf lifespan have been rigorously investigated, there is a limited understanding of similar linkages of whole-plant and fine root traits to root lifespan. In comparisons across species, do suites of traits found in leaves also exist for roots, and can these traits be used to predict root lifespan?, We observed the fine root lifespan of 12 temperate tree species using minirhizotrons in a common garden and compared their median lifespans with fine-root and whole-plant traits. We then determined which set of combined traits would be most useful in predicting patterns of root lifespan., Median root lifespan ranged widely among species (95-336 d). Root diameter, calcium content, and tree wood density were positively related to root lifespan, whereas specific root length, nitrogen (N) : carbon (C) ratio, and plant growth rate were negatively related to root lifespan. Root diameter and plant growth rate, together ( R2 = 0.62) or in combination with root N : C ratio ( R2 = 0.76), were useful predictors of root lifespan across the 12 species., Our results highlight linkages between fine root lifespan in temperate trees and plant functional traits that may reduce uncertainty in predictions of root lifespan or turnover across species at broader spatial scales. [ABSTRACT FROM AUTHOR]

English schools have traditionally been institutions with high levels of homophobia. This is attributed to the need that heterosexual boys have to maintain a heteromasculine identity. However, by drawing on 44 in-depth interviews and 12 months of participant observation across three sixth forms, I detail the ways in which homophobia holds little cultural sway with the heterosexual male students in these settings. Here, the majority of students intellectualise pro-gay attitudes, maintain friendships with openly gay students and are physically tactile with each other. Homophobic discourse is rarely heard and it is even stigmatised in two of the settings. Homosexually-themed language that I call 'gay discourse' replaces it. This discourse maintains socio-negative effect, but it is also used by openly gay students to bond with their heterosexual peers. Accordingly, this research shows that cultural homophobia maintains less significance than has been documented in previous studies. [ABSTRACT FROM AUTHOR]

Soil fungi couple plant and ecosystem resource demands to pools of soil resources. Research on these organisms is needed to predict how rising atmospheric CO2 will influence forest ecosystem processes and soil carbon (C) sequestration potential. We examined the influence of free-air-CO2-enrichment (FACE) on mycorrhizal and extraradical rhizomorph dynamics over a 5-year period in a loblolly pine forest using minirhizotrons. Standing crop of mycorrhizal root tips varied greatly spatially and through time. Summed across all years, CO2 enrichment increased mycorrhizal root tip production by 194% in deep soil (15–30 cm) but did not influence mycorrhizal production in shallow soil (0–15 cm). Production and mortality of soil rhizomorph length was 27% and 25% greater in CO2-enriched plots compared with controls over a 5-year period beginning in January of 2000 and running through autumn 2004. Effects of atmospheric CO2 enrichment on longevity of mycorrhizal root tips and rhizomorphs varied with soil depth (mycorrhizae and rhizomorphs) and with diameter (rhizomorphs). For instance, survival of mycorrhizal tips was reduced in CO2-enriched plots in deep soil (15–30 cm depth) but was increased in shallower soil (0–15 cm). Rhizomorph turnover was accelerated in shallow soil but effects on survivorship in deep soil varied according to diameter. A drought in 2002 coupled with loss of leaf area to an ice storm late in 2002 were followed by reductions in rhizomorph and mycorrhizal production, increases in mortality, and decreases in standing crop during 2003 and 2004. These effects tended to be more severe in CO2-enriched plots. Positive effects of atmospheric CO2 enrichment on mycorrhizal fungi, primarily observed in deeper soil, are probably contributing to the prolonged stimulation of NPP by CO2 enrichment at the Duke FACE study site. [ABSTRACT FROM AUTHOR]

Efforts to characterize carbon (C) cycling among atmosphere, forest canopy, and soil C pools are hindered by poorly quantified fine root dynamics. We characterized the influence of free-air-CO2-enrichment (ambient +200 ppm) on fine roots for a period of 6 years (Autumn 1998 through Autumn 2004) in an 18-year-old loblolly pine ( Pinus taeda) plantation near Durham, NC, USA using minirhizotrons. Root production and mortality were synchronous processes that peaked most years during spring and early summer. Seasonality of fine root production and mortality was not influenced by atmospheric CO2 availability. Averaged over all 6 years of the study, CO2 enrichment increased average fine root standing crop (+23%), annual root length production (+25%), and annual root length mortality (+36%). Larger increase in mortality compared with production with CO2 enrichment is explained by shorter average fine root lifespans in elevated plots (500 days) compared with controls (574 days). The effects of CO2-enrichment on fine root proliferation tended to shift from shallow (0–15 cm) to deeper soil depths (15–30) with increasing duration of the study. Diameters of fine roots were initially increased by CO2-enrichment but this effect diminished over time. Averaged over 6 years, annual fine root NPP was estimated to be 163 g dw m−2 yr−1 in CO2-enriched plots and 130 g dw m−2 yr−1 in control plots ( P= 0.13) corresponding to an average annual additional input of fine root biomass to soil of 33 g m−2 yr−1 in CO2-enriched plots. A lack of consistent CO2× year effects suggest that the positive effects of CO2 enrichment on fine root growth persisted 6 years following minirhizotron tube installation (8 years following initiation of the CO2 fumigation). Although CO2-enrichment contributed to extra flow of C into soil in this experiment, the magnitude of the effect was small suggesting only modest potential for fine root processes to directly contribute to soil C storage in south-eastern pine forests. [ABSTRACT FROM AUTHOR]

- We assessed the agreement between 2 methods of data gathering of particular interest in urology: patient questionnaire and examination vs. frequency-volume charts. One hundred consecutive patients consulting our out-patient clinic were chosen for this study; 88 completed the study. Urinary frequency and bladder capacity were evaluated in each patient by using the above methods. The agreement between different methods of measurement was assessed by determining whether the 2 methods were interchangeable, a condition occurring if results of both methods fall within predetermined limits of variability. The results showed poor agreement between subjectively estimated unnary frequency and chart-determined urinary frequency. Moreover, different methods of measuring bladder capacity (endoscopic vs. chart) gave different results. Since chart-determined data are probably a more valid indication of urinary habits, we suggest that frequency-volume charts should be used more often in the investigation and follow-up of patients with micturition disorders. [ABSTRACT FROM AUTHOR]

Information on the 96th Annual Meeting of the Ecological Society of America held in Austin, Texas on August 10, 2011 is presented. Topics include belowground processes, carbon (C) cost of nitrogen (N) uptake modeling in the Fixation and Uptake of Nitrogen (FUN) module, and ectomycorrhizal fungi. The meeting featured several speakers including Erik Hobbie of University of New Hampshire, Kirsten Hofmockel of Iowa State University, and David Eissenstat of The Pennsylvania State University.