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The genus Cortinarius (Agaricales, Basidiomycota) is one of the most species-rich fungal genera, with thousands of species reported. Cortinarius species are important ectomycorrhizal fungi and form associations with many vascular plants globally. Until recently Cortinarius was the single genus of the family Cortinariaceae, despite several attempts to provide a workable, lower-rank hierarchical structure based on subgenera and sections. The first phylogenomic study for this group elevated the old genus Cortinarius to family level and the family was split into ten genera, of which seven were described as new. Here, by careful re-examination of the recently published phylogenomic dataset, we detected extensive gene-tree/species-tree conflicts using both concatenation and multispecies coalescent approaches. Our analyses demonstrate that the Cortinarius phylogeny remains unresolved and the resulting phylogenomic hypotheses suffer from very short and unsupported branches in the backbone. We can confirm monophyly of only four out of ten suggested new genera, leaving uncertain the relationships between each other and the general branching order. Thorough exploration of the tree space demonstrated that the topology on which Cortinarius revised classification relies on does not represent the best phylogenetic hypothesis and should not be used as constrained topology to include additional species. For this reason, we argue that based on available evidence the genus Cortinarius should not (yet) be split. Moreover, considering that phylogenetic uncertainty translates to taxonomic uncertainty, we advise for careful evaluation of phylogenomic datasets before proposing radical taxonomic and nomenclatural changes. [ABSTRACT FROM AUTHOR]

Background: Arbuscular mycorrhizal (AM) symbiosis has been referred to as the mother of all plant root symbioses as it predated the evolution of plant roots. The AM research is a multidisciplinary field at the intersection of soil science, mycology, and botany. However, in recent decades the nature and properties of soils, in which the AM symbiosis develops and functions, have received less attention than desired. Scope: In this review we discuss a number of recent developments in AM research. We particularly cover the role of AM symbiosis in acquisition of phosphorus, nitrogen, heavy metals and metalloids, as well as water by plants from soil; mycorrhizal effects on plant nutritional stoichiometry and on the carbon cycle; the hyphosphere microbiome; so-called facultative mycorrhizal plants; explanations for lack of mycorrhizal benefit; common mycorrhizal networks; and arbuscular and ectomycorrhizal ecosystems. Conclusion: We reflect on what has previously been described as mycorrhizal 'dogmas'. We conclude that these are in fact generalisations on the AM symbiosis that are well supported by multiple studies, while admitting that there potentially is a geographical bias in mycorrhizal research that developed in temperate and boreal regions, and that research in other ecosystems might uncover a greater diversity of viable mycorrhizal and non-mycorrhizal strategies than currently acknowledged. We also note an increasing tendency to overinterpret data, which may lead to stagnation of some research fields due to lack of experiments designed to test the mechanistic basis of processes rather than cumulating descriptive studies and correlative evidences. [ABSTRACT FROM AUTHOR]

Tree performance depends on the coordinated functioning of interdependent leaves, stems and (mycorrhizal) roots. Integrating plant organs and their traits, therefore, provides a more complete understanding of tree performance than studying organs in isolation. Until recently, our limited understanding of root traits impeded such a whole‐tree perspective on performance, but recent developments in root ecology provide new impetuses for integrating the below‐ and aboveground. Here, we identify two key avenues to further develop a whole‐tree perspective on performance and highlight the conceptual and practical challenges and opportunities involved in including the belowground. First, traits of individual roots need to be scaled up to the root system as a whole to determine belowground functioning, e.g. total soil water and nutrient uptake, and hence performance. Second, above‐ and belowground plant organs need to be mechanistically connected to account for how they functionally interact and to investigate their combined impacts on tree performance. We further identify mycorrhizal symbiosis as the next frontier and emphasize several courses of actions to incorporate these symbionts in whole‐tree frameworks. By scaling up and mechanistically integrating (mycorrhizal) roots as argued here, the belowground can be better represented in whole‐tree conceptual and mechanistic models; ultimately, this will improve our estimates of not only the functioning and performance of individual trees, but also the processes and responses to environmental change of the communities and ecosystems they are part of. [ABSTRACT FROM AUTHOR]

Aims: Cereal/legume intercropping has advantages in yield and nutrient uptake. However, how common mycorrhizal networks (CMNs), formed by arbuscular mycorrhizal fungi (AMF) play a role in those benefits has not been fully clarified. This study aimed to explore how CMNs initiated by different host plants affected plant performance and nutrient acquisition in a maize/soybean mixture.Microcosms with three compartments were used; these were separated by 30-µm nylon mesh. Two compartments were root compartments (RCs), and the third compartment was a hyphal compartment (HC). One RC was inoculated with the AMF Rhizophagus irregularis and the plant in this compartment was referred to as CMNs donor, and the plant in the other RC compartment as CMNs receiver.Maize biomass was twice that of soybean. Nitrogen (N) and phosphorus (P) content of both maize and soybean were higher in the presence of CMNs compared with the treatment without AMF. When maize was the CMNs donor, shoot biomass, N and P content of the maize/soybean mixture were higher than the expected biomass, N and P content based on monocultures, suggesting overyielding. However, the overyielding was not observed when soybean was the CMNs donor.Overyielding in a maize/soybean mixture depends on the initiator of CMNs. With maize as CMNs donor, both species in the mixture benefited from CMNs compared with monocultures.Methods: Cereal/legume intercropping has advantages in yield and nutrient uptake. However, how common mycorrhizal networks (CMNs), formed by arbuscular mycorrhizal fungi (AMF) play a role in those benefits has not been fully clarified. This study aimed to explore how CMNs initiated by different host plants affected plant performance and nutrient acquisition in a maize/soybean mixture.Microcosms with three compartments were used; these were separated by 30-µm nylon mesh. Two compartments were root compartments (RCs), and the third compartment was a hyphal compartment (HC). One RC was inoculated with the AMF Rhizophagus irregularis and the plant in this compartment was referred to as CMNs donor, and the plant in the other RC compartment as CMNs receiver.Maize biomass was twice that of soybean. Nitrogen (N) and phosphorus (P) content of both maize and soybean were higher in the presence of CMNs compared with the treatment without AMF. When maize was the CMNs donor, shoot biomass, N and P content of the maize/soybean mixture were higher than the expected biomass, N and P content based on monocultures, suggesting overyielding. However, the overyielding was not observed when soybean was the CMNs donor.Overyielding in a maize/soybean mixture depends on the initiator of CMNs. With maize as CMNs donor, both species in the mixture benefited from CMNs compared with monocultures.Results: Cereal/legume intercropping has advantages in yield and nutrient uptake. However, how common mycorrhizal networks (CMNs), formed by arbuscular mycorrhizal fungi (AMF) play a role in those benefits has not been fully clarified. This study aimed to explore how CMNs initiated by different host plants affected plant performance and nutrient acquisition in a maize/soybean mixture.Microcosms with three compartments were used; these were separated by 30-µm nylon mesh. Two compartments were root compartments (RCs), and the third compartment was a hyphal compartment (HC). One RC was inoculated with the AMF Rhizophagus irregularis and the plant in this compartment was referred to as CMNs donor, and the plant in the other RC compartment as CMNs receiver.Maize biomass was twice that of soybean. Nitrogen (N) and phosphorus (P) content of both maize and soybean were higher in the presence of CMNs compared with the treatment without AMF. When maize was the CMNs donor, shoot biomass, N and P content of the maize/soybean mixture were higher than the expected biomass, N and P content based on monocultures, suggesting overyielding. However, the overyielding was not observed when soybean was the CMNs donor.Overyielding in a maize/soybean mixture depends on the initiator of CMNs. With maize as CMNs donor, both species in the mixture benefited from CMNs compared with monocultures.Conclusion: Cereal/legume intercropping has advantages in yield and nutrient uptake. However, how common mycorrhizal networks (CMNs), formed by arbuscular mycorrhizal fungi (AMF) play a role in those benefits has not been fully clarified. This study aimed to explore how CMNs initiated by different host plants affected plant performance and nutrient acquisition in a maize/soybean mixture.Microcosms with three compartments were used; these were separated by 30-µm nylon mesh. Two compartments were root compartments (RCs), and the third compartment was a hyphal compartment (HC). One RC was inoculated with the AMF Rhizophagus irregularis and the plant in this compartment was referred to as CMNs donor, and the plant in the other RC compartment as CMNs receiver.Maize biomass was twice that of soybean. Nitrogen (N) and phosphorus (P) content of both maize and soybean were higher in the presence of CMNs compared with the treatment without AMF. When maize was the CMNs donor, shoot biomass, N and P content of the maize/soybean mixture were higher than the expected biomass, N and P content based on monocultures, suggesting overyielding. However, the overyielding was not observed when soybean was the CMNs donor.Overyielding in a maize/soybean mixture depends on the initiator of CMNs. With maize as CMNs donor, both species in the mixture benefited from CMNs compared with monocultures. [ABSTRACT FROM AUTHOR]

Keywords: Rapeseed; Broomrape; Soil microbiota; Isothiocyanate; Pesticide treadmill EN Rapeseed Broomrape Soil microbiota Isothiocyanate Pesticide treadmill 693 695 3 02/21/23 20230201 NES 230201 Plants perceive and have the capacity to adaptively respond to environmental signals, both aboveground and belowground. In this issue of Plant and Soil, Martinez et al. ([9]) report a number of elegant assays that demonstrate that this microbial conversion of glucosinolates to isothiocyanates stimulates germination of I P. ramosa i . A direct germination test in 96-well plates indicated no germination of I P. ramosa i seeds with soil extracts; however, if gluconasturtiin (the main glucosinolate of rapeseed) was added to soil extracts, germination was very high, whereas addition of only gluconasturtiin did not result in seed germination of I P. ramosa i . [Extracted from the article]

The concept of ecosystem services (ES) and related conceptual frameworks like the cascade model, can be relevant to explore the ways through which people and nature are connected and how the benefits of nature, upon which people depend, are realised. An integrated cascade framework was used to study the ES pathway of pine resin, a traded forest product, in a rural mountain community in Mexico. We conducted mixed-methods research, combining participatory tools with measures of service capacity, resin yield, and key farmer endowments. Resin was co-produced by an intricate interaction between the human and natural components of the social-ecological system. Substantial human inputs and coordinated efforts were required to realise resin benefits, and people's appreciation and plural values emerged along the whole service pathway. Though there were stark differences in natural resource endowments, working farmers gained a high share of resin's income through labour, labour relations and social networks. But most social conflicts and struggles also occurred over labour relations and organisation, revealing power dynamics. Furthermore, external actors controlled different mechanisms of access, and exerted power over the community's ability to derive benefits from resin. In resin co-production, values connect people to the landscape, while labour and power mediate the access to nature's benefits. [ABSTRACT FROM AUTHOR]

Background: Soil organic matter (SOM) supports multiple soil ecosystem functions, underpinned by processes such as C sequestration, N mineralization, aggregation, promotion of plant health and compound retention. We know little about the relationship between these functions and SOM quality. Scope: We aimed to develop "eco-functionality" as a framework to address questions on the relation between SOM properties and soil ecosystem functions. Conclusions: Paradigm shifts in SOM research have not led to metrics for eco-functionality beyond decomposability and C:N ratio. Recalcitrant OM is under-researched despite its essential role in aggregation and C sequestration, especially in C-saturated soils. Most soil functions are dependent on SOM decomposition and require labile compounds. We conclude that eco-functionality is context-dependent and needs to take time scales into account. We plea for attempts to link operationally defined SOM fractions to functions in order to make SOM research more applicable. [ABSTRACT FROM AUTHOR]

Aims: The phosphorus (P) resource partitioning hypothesis assumes that dissimilarity in P acquisition traits among plant species leads to enhanced P uptake by crop combinations compared with their sole crops. We developed and implemented a test for this hypothesis. Methods: Two pot experiments were conducted with quartz sands. In Experiment 1, the ability of the crop species to acquire P from sparingly soluble sources (Ca phosphate (CaP), phytate (PhyP) and P-coated Fe (hydr)oxide (FeP)) was tested. In accordance with the species performances in Experiment 1, combinations of millet/chickpea and cabbage/faba bean (which have dissimilar P acquisition traits) and wheat/maize (which have similar traits) were selected for Experiment 2. The biomass production and P uptake were compared between the sole crops and species combinations as well as between the single and mixed P sources. Results: A dissimilarity in P acquisition traits enhanced P uptake by millet/chickpea on CaP/PhyP (as expected) but not by cabbage/faba bean on FeP/PhyP. Despite their similar P acquisition traits, we found enhanced P uptake by wheat/maize on CaP/PhyP. Conclusions: Because of complicating factors such as unstable P acquisition traits and competitive inequality between species, the conditions under which the P resource partitioning hypothesis can be tested are limited. This challenge complicates designing for complementarity in soil P pools by intercrops. [ABSTRACT FROM AUTHOR]

Aims: Roots contribute greatly to carbon cycling in agriculture. Measuring aboveground litter decomposition could approximate belowground turn-over if drivers of decomposition, f.e. litter traits and plant presence, influence shoot and root decomposition in a comparable manner. We tested coordination of above- and belowground litter traits and decomposition rates for six pairs of crops and closely related wild plants and studied the influence of plant presence on decomposition. Methods: Above- and belowground traits were measured, compared and related to decomposition rates. Shoot and root litters were incubated in presence of the same plant species as the litter species (own) or in presence of two other plant species (a grass or forb). Results: Shoots decomposed 1.43–1.98 times faster than (resp.) wild plant and crop roots. Decomposition correlated negatively with litter carbon and lignin concentrations, except crop root decomposition which correlated negatively with nitrogen concentration. Unexpectedly, plant presence reduced litter decomposition, with strongest effects for root litters in presence of forbs. Conclusions: Carbon cycling might be slower than predicted solely based on shoots decomposition rates, especially in presence of growing plants. While root decomposition of wild plants can be approximated by shoot decomposition, crop shoots are a poor proxy for crop root decomposition. [ABSTRACT FROM AUTHOR]

In agriculture, winter cover crop (WCC) residues are incorporated into the soil to improve soil quality, as gradual litter decomposition can improve fertility. Decomposition rate is determined by litter quality, local soil abiotic and biotic properties. How these factors are interlinked and influenced by cropping history is, however, unclear.We grew WCC monocultures and mixtures in rotation with main crops Avena sativa (oat) and Cichorium endivia (endive) and tested how crop rotation influences WCC litter quality, abiotic and biotic soil conditions, and litter decomposition rates. To disentangle WCC litter quality effects from WCC soil legacy effects on decomposition, we tested how rotation history influences decomposition of standard substrates and explored the underlying mechanisms.In a common environment (e.g. winter fallow plots), WCC decomposition rate constants (k) correlated negatively with litter C, lignin and, surprisingly, N content, due to strong positive correlations among these traits. Plots with a history of fast‐decomposing WCCs exhibited faster decomposition of their own litters as well as of the standard substrates filter paper and rooibos tea, as compared to winter fallow plots.WCC treatments differentially affected soil microbial biomass, as well as soil organic matter and mineral nitrogen content. WCC‐induced soil changes affected decomposition rates. Depending on the main crop rotation treatment, legacy effects were attributed to biomass input of WCCs and their litter quality or changes in microbial biomass.Synthesis and applications. These results demonstrate that decomposition in cropping systems is influenced directly through crop residues, as well as through crop‐induced changes in soil biotic properties. Rotation history influences decomposition, wherein productive winter cover crops (WCC) with low lignin content decompose fast and stimulate the turnover of both own and newly added residues via their knock‐on effect on the soil microbial community. Thus, WCC have promise for sustainable carbon‐ and nutrient‐cycling management through litter feedbacks. These results demonstrate that decomposition in cropping systems is influenced directly through crop residues, as well as through crop‐induced changes in soil biotic properties. Rotation history influences decomposition, wherein productive winter cover crops (WCC) with low lignin content decompose fast and stimulate the turnover of both own and newly added residues via their knock‐on effect on the soil microbial community. Thus, WCC have promise for sustainable carbon‐ and nutrient‐cycling management through litter feedbacks. [ABSTRACT FROM AUTHOR]

This article is a Commentary on Wang et al. (2020), 228: 697–711. [ABSTRACT FROM AUTHOR]

Plant diversity can increase nitrogen cycling and decrease soil-borne pests, which are feedback mechanisms influencing subsequent plant growth. The relative strength of these mechanisms is unclear, as is the influence of preceding plant quantity and quality. Here, we studied how plant diversity in space and time influences subsequent crop growth., During 2 years, we rotated two main crops ( Avena sativa, Cichorium endivia) with four winter cover crop ( WCC) species in monocultures and mixtures. We hypothesized that, relative to monocultures, WCC mixtures promote WCC biomass (quantity) and nitrogen concentration (quality), soil mineral nitrogen, soil organic matter, and reduce plant-feeding nematode abundance. Additionally, we predicted that preceding crops modified WCC legacies. By structural equation modelling ( SEM), we tested the relative importance of WCC shoot biomass and nitrogen concentration on succeeding crop productivity directly and indirectly via nitrogen cycling and root-feeding nematode abundance., WCC shoot biomass, soil properties and succeeding Avena productivity were affected by first-season cropping, whereas subsequent Cichorium only responded to the WCC treatments. WCC mixtures' productivity and nitrogen concentration showed over- and under-yielding, depending on mixture composition. Soil nitrogen and nematode abundance did not display WCC mixture effects. Soil organic matter was lower than expected after Raphanus sativus + Vicia sativa mixture. Subsequent Avena productivity depended upon mixture composition, whereas final Cichorium productivity was unresponsive to WCC mixtures. SEM indicated that WCC legacy effects on subsequent Avena ( R2 = 0.52) and Cichorium ( R2 = 0.59) productivity were driven by WCC biomass and nitrogen concentration , although not by the quantified soil properties., Synthesis and applications. Through understanding plant-soil feedback, legacy effects of plant species and species mixtures can be employed for sustainable management of agro-ecosystems. Biomass and nitrogen concentration of plants returned to the soil stimulate subsequent plant productivity. Winter cover crop quantity and quality are both manipulable with mixtures. The specificity of spatial and temporal diversity effects warrants consideration of plant species choice in mixtures and rotations for optimal employment of beneficial legacy effects. [ABSTRACT FROM AUTHOR]

Thermophilic composting produces a significant amount of greenhouse gases. The objectives of this study were (i) to evaluate the effectiveness of vermicomposting to reduce nitrogen losses and greenhouse gases emissions compared to thermophilic composting, and (ii) to determine the effect of different variables ( i.e. carbon:nitrogen ratio, earthworm density, moisture content and carbon quality) on greenhouse gases emissions and earthworm growth during vermicomposting. The results showed that vermicomposting significantly reduced nitrogen loss by 10–20% compared to thermophilic composting. Vermicomposting decreased nitrous oxide emissions by 25–36% and methane emissions by 22–26%. A higher earthworm density increased carbon dioxide emissions by 3–14%, but decreased methane emissions by 10–35%. Earthworm density had a marginal effect on nitrous oxide emissions. Vermicomposting decreased nitrous oxide emissions by 40% with higher moisture and by 23% with lower moisture. Vermicomposting also decreased methane emissions by 32% and 16% with higher and lower moistures respectively. This study showed that the addition of labile carbon sources increased carbon dioxide and methane emissions and earthworm growth, but did not affect nitrous oxide emissions. In conclusion, vermicomposting is effective at reducing nitrogen losses and greenhouse gas emissions from composting. Therefore, vermicomposting could represent an option for reducing greenhouse gas emissions from composting, particularly in developing countries where the existing technical solutions are expensive and difficult to implement. [ABSTRACT FROM AUTHOR]

We formulate five guidelines for introducing new genera, plus one recommendation how to publish the results of scientific research. We recommend that reviewers and editors adhere to these guidelines. We propose that the underlying research is solid, and that the results and the final solutions are properly discussed. The six criteria are: (1) all genera that are recognized should be monophyletic; (2) the coverage of the phylogenetic tree should be wide in number of species, geographic coverage, and type species of the genera under study; (3) the branching of the phylogenetic trees has to have sufficient statistical support; (4) different options for the translation of the phylogenetic tree into a formal classification should be discussed and the final decision justified; (5) the phylogenetic evidence should be based on more than one gene; and (6) all supporting evidence and background information should be included in the publication in which the new taxa are proposed, and this publication should be peer-reviewed. [ABSTRACT FROM AUTHOR]

We formulate five guidelines for introducing new genera, plus one recommendation how to publish the results of scientific research. We recommend that reviewers and editors adhere to these guidelines. We propose that the underlying research is solid, and that the results and the final solutions are properly discussed. The six criteria are: (1) all genera that are recognized should be monophyletic; (2) the coverage of the phylogenetic tree should be wide in number of species, geographic coverage, and type species of the genera under study; (3) the branching of the phylogenetic trees has to have sufficient statistical support; (4) different options for the translation of the phylogenetic tree into a formal classification should be discussed and the final decision justified; (5) the phylogenetic evidence should be based on more than one gene; and (6) all supporting evidence and background information should be included in the publication in which the new taxa are proposed, and this publication should be peer-reviewed. [ABSTRACT FROM AUTHOR]

The use of agricultural waste for soil amendment is limited in developing countries. Competition between fuel and feed is the major cause for the insufficient application of agricultural waste on cropland. The aims of this study were therefore (i) to investigate variation in agricultural waste allocation between groups of farmers with different livelihood strategies and link this allocation with the nutrient balances of their production systems, (ii) to identify farm characteristics that influence utilisation of agricultural waste for soil amendment, and (iii) to assess demand for urban waste compost. A total of 220 farmers were selected randomly and interviewed using standardised semi-structured questionnaires. Four groups of farmers, namely (i) field crop farmers, (ii) vegetable producers, (iii) ornamental-plant growers, and (iv) farmers practising mixed farming, were identified using categorical principal component and two-step cluster analyses. Field crop farmers produced the largest quantity of agricultural waste, but they allocated 80% of manure to fuel and 85% of crop residues to feed. Only <10% of manure and crop residues were applied on soils. Farmers also sold manure and crop residues, and this generated 5–10% of their annual income. Vegetable and ornamental-plant growers allocated over 40% of manure and crop residues to soil amendment. Hence, nutrient balances were less negative in vegetable production systems. Education, farm size, land tenure and access to extension services were the variables that impeded allocation of agricultural waste to soil amendment. Replacement of fuel and feed through sustainable means is a viable option for soil fertility management. Urban waste compost should also be used as alternative option for soil amendment. Our results showed variation in compost demand between farmers. Education, landownership, experience with compost and access to extension services explained variation in compost demand. We also demonstrated that labour availability should be used to estimate compost demand beside cash. [ABSTRACT FROM AUTHOR]

Background:Arbuscular mycorrhizal (AM) fungi increase seedling survival and performance through enhancement of nutrient and water uptake under stress conditions.Acacia etbaica, A. senegalandBoswellia papyriferadominate large areas in African drylands where both moisture and nutrients are limited. Aims:We evaluated the effects of AM, drought and soil quality on carbon gain (growth), gas exchange and nutrient contents of seedlings of these three dry woodland species. Methods:We used a greenhouse experiment with a fully factorial design of two levels of AM, two levels of soil and four levels of water availability, on the carbon gain, gas exchange and nutrient content of seedlings of the three species. Results:AM symbiosis enhanced the acquisition of water and nutrients and increased gas exchange resulting in increasedAcaciaandBoswelliaseedling biomass. The rapidly growingAcaciaspecies (acquisitive strategy) showed larger mycorrhizal benefit at higher water availability. The slow-growingBoswellia(conservative strategy), in contrast, showed larger mycorrhizal benefit at lower water availability. Conclusions:This study showed that different species of dry woodlands benefit from AM in different ways depending on the resource use strategy under stress conditions. The inclusion of the mycorrhizal habit in trait-based approaches increases understanding of functional differences of coexisting tree species. [ABSTRACT FROM PUBLISHER]

This article is a Commentary on Liang et al., 230: 2061–2071. [ABSTRACT FROM AUTHOR]

Information is lacking on habitat and diversity of ectomycorrhizal (ECM) fungi of African humid forests. For three years, mushroom excursions were carried out in four sites with contrasted soil and altitude characteristics of South Cameroon, during wet seasons. Collected fungi were described in fresh state and dried exsiccates examined for microscopic description before morpho-anatomical identification. ECM fungi abundantly fruited exclusively in mixed caesalp, monodominant Gilbertiodendron and Uapaca forest clumps, independently of elevation, rainfall, topography and soil texture. 21 ECM tree species in 11 genera belonging to two families, Ceasalpiniaceae and Phyllanthaceae, dominated ECM forest clumps. More than 100 putative ECM fungal species in 27 genera were identified and assigned to seven families and one super family group. Members of Russulaceae and Amanitaceae recruited the highest number of ECM taxa, followed by species of Boletoids and Cantharellaceae. Paxillus, Clavulina, Coltricia, Scleroderma, Cortinarius and Inocybe genera contained limited species. 12 ECM fungal species were locally edible, including Lactarius gymnocarpus and all chanterelles. Though, species richness was very large in a mountainous area, all four sites shared a substantial large number of ECM mushroom species. Low plant diversity but high fungal richness recommends ECM forest clumps for biodiversity sanctuaries. [ABSTRACT FROM AUTHOR]

Although increasing concentrations of atmospheric CO2 are predicted to have substantial impacts on plant growth and functioning of ecosystems, there is insufficient understanding of the responses of belowground processes to such increases. We investigated the effects of different dark septate root endophytic (DSE) fungi on growth and nutrient acquisition by Pinus sylvestris seedlings under conditions of N limitation and at ambient and elevated CO2 (350 or 700 μ1 CO2 l−1). Each seedling was inoculated with one of the following species: Phialocephala fortinii (two strains), Cadophora finlandica, Chloridium paucisporum, Scytalidium vaccinii, Meliniomyces variabilis and M. vraolstadiae. The trial lasted 125 days. During the final 27 days, the seedlings were labeled with 14CO2 and 15NH. We measured extraradical hyphal length, internal colonization, plant biomass, 14C allocation, and plant N and 15N content. Under elevated CO2, the biomass of seedlings inoculated with DSE fungi was on average 17% higher than in control seedlings. Simultaneously, below-ground respiration doubled or trebled, and as a consequence carbon use efficiency by the DSE fungi significantly decreased. Shoot N concentration decreased on average by 57% under elevated CO2 and was lowest in seedlings inoculated with S. vaccinii. Carbon gain by the seedlings despite reduced shoot N concentration indicates that DSE fungi increase plant nutrient use efficiency and are therefore more beneficial to the plant under elevated CO2. [ABSTRACT FROM AUTHOR]

Abstract: Rhizobial and arbuscular mycorrhizal (AM) symbioses each may consume 4–16% of recently photosynthetically-fixed carbon to maintain their growth, activity and reserves. Rhizobia and AM fungi improve plant photosynthesis through N and P acquisition, but increased nutrient uptake by these symbionts does not fully explain observed increases in the rate of photosynthesis of symbiotic plants. In this paper, we test the hypothesis that carbon sink strength of rhizobial and AM symbioses stimulates the rates of photosynthesis. Nutrient-independent effects of rhizobial and AM symbioses result in direct compensation of C costs at the source. We calculated the response ratios of photosynthesis and nutrient mass fraction in the leaves of legumes inoculated with rhizobial and/or AM fungi relative to non-inoculated plants in a number of published studies. On average, photosynthetic rates were significantly increased by 28 and 14% due to rhizobial and AM symbioses, respectively, and 51% due to dual symbiosis. The leaf P mass fraction was increased significantly by 13% due to rhizobial symbioses. Although the increases were not significant, AM symbioses increased leaf P mass fraction by 6% and dual symbioses by 41%. The leaf N mass fraction was not significantly affected by any of the rhizobial, AM and dual symbioses. The rate of photosynthesis increased substantially more than the C costs of the rhizobial and AM symbioses. The inoculation of legumes with rhizobia and/or AM fungi, which resulted in sink stimulation of photosynthesis, improved the photosynthetic nutrient use efficiency and the proportion of seed yield in relation to the total plant biomass (harvest index). Sink stimulation represent an adaptation mechanism that allows legumes to take advantage of nutrient supply from their microsymbionts without compromising the total amount of photosynthates available for plant growth. [Copyright &y& Elsevier]

The ectomycorrhizal (ECM) symbiosis can cause both positive and negative feedback with trees under elevated CO2. Positive feedback arises if the additional carbon (C) increases both nutrient uptake by the fungus and nutrient transfer to the plant, whereas negative feedback results from increased nutrient uptake and immobilization by the fungus and reduced transfer to the plant. Because species of ECM fungi differ in their C and nitrogen (N) demand, understanding fungal species-specific responses to variation in C and N supply is essential to predict impacts of global change. We investigated fungal species-specific responses of ECM Scots pine ( Pinus sylvestris) seedlings under ambient and elevated CO2 (350 or 700 μL L−1 CO2) and under low and high mineral N availability. Each seedling was associated with one of the following ECM species: Hebeloma cylindrosporum, Laccaria bicolor and Suillus bovinus. The experiment lasted 103 days. During the final 27 days, seedlings were labeled with 14CO2 and 15N. Most plant and fungal parameters were significantly affected by fungal species, CO2 level and N supply. Interactions between fungal species and CO2 were also regularly significant. At low N availability, elevated CO2 had the smallest impact on the photosynthetic performance of seedlings inoculated with H. cylindrosporum and the largest impact on seedlings with S. bovinus. At ambient CO2, increasing N supply had the smallest impact on seedlings inoculated with S. bovinus and the largest on seedlings inoculated with H. cylindrosporum. At low N availability, extraradical hyphal length increased after doubling CO2 level, but this was significant only for L. bicolor. At ambient CO2, increasing N levels reduced hyphal length for both H. cylindrosporum and S. bovinus, but not for L. bicolor. We discuss the potential interplay of two major elements of global change, elevated CO2 and increased N availability, and their effects on plant growth. We conclude that increased N supply potentially relieves mycorrhiza-induced progressive N limitation under elevated CO2. [ABSTRACT FROM AUTHOR]

A decade ago, tunnels inside mineral grains were found that were likely formed by hyphae of ectomycorrhizal (EcM) fungi. This observation implied that EcM fungi can dissolve mineral grains. The observation raised several questions on the ecology of these “rock-eating” fungi. This review addresses the roles of these rock-eating EcM associations in plant nutrition, biogeochemical cycles and pedogenesis. Research approaches ranged from molecular to ecosystem level scales. Nutrient deficiencies change EcM seedling exudation patterns of organic anions and thus their potential to mobilise base cations from minerals. This response was fungal species-specific. Some EcM fungi accelerated mineral weathering. While mineral weathering could also increase the concentrations of phytotoxic aluminium in the soil solution, some EcM fungi increase Al tolerance through an enhanced exudation of oxalate. Through their contribution to Al transport, EcM hyphae could be agents in pedogenesis, especially podzolisation. A modelling study indicated that mineral tunnelling is less important than surface weathering by EcM fungi. With both processes taken together, the contribution of EcM fungi to weathering may be significant. In the field vertical niche differentiation of EcM fungi was shown for EcM root tips and extraradical mycelium. In the field EcM fungi and tunnel densities were correlated. Our results support a role of rock-eating EcM fungi in plant nutrition and biogeochemical cycles. EcM fungal species-specific differences indicate the need for further research with regard to this variation in functional traits. [ABSTRACT FROM AUTHOR]

We investigated fungal species-specific responses of ectomycorrhizal (ECM) Scots pine ( Pinus sylvestris) seedlings on growth and nutrient acquisition together with mycelial development under ambient and elevated CO2. Each seedling was associated with one of the following ECM species: Hebeloma cylindrosporum, Laccaria bicolor, Suillus bovinus, S. luteus, Piloderma croceum, Paxillus involutus, Boletus badius, or non-mycorrhizal, under ambient, and elevated CO2 (350 or 700 μl l−1 CO2); each treatment contained six replicates. The trial lasted 156 days. During the final 28 days, the seedlings were labeled with 14CO2. We measured hyphal length, plant biomass, 14C allocation, and plant nitrogen and phosphorus concentration. Almost all parameters were significantly affected by fungal species and/or CO2. There were very few significant interactions. Elevated CO2 decreased shoot-to-root ratio, most strongly so in species with the largest extraradical mycelium. Under elevated CO2, ECM root growth increased significantly more than hyphal growth. Extraradical hyphal length was significantly negatively correlated with shoot biomass, shoot N content, and total plant N uptake. Root dry weight was significantly negatively correlated with root N and P concentration. Fungal sink strength for N strongly affected plant growth through N immobilization. Mycorrhizal fungal-induced progressive nitrogen limitation (PNL) has the potential to generate negative feedback with plant growth under elevated CO2. [ABSTRACT FROM AUTHOR]

The authors wish to report an error in the original version of the paper. In figure 4, panels a) and b) are incorrectly titled respectively "Crop shoots" and "Crop roots". [ABSTRACT FROM AUTHOR]

Abstract: Major factors that constrain tropical soil fertility and sustainable agriculture are low nutrient capital, moisture stress, erosion, high P fixation, high acidity with aluminium toxicity, and low soil biodiversity. The fragility of many tropical soils limits food production in annual cropping systems. Because some tropical soils under natural conditions have high biological activity, an increased use of the biological potential of these soils to counter the challenges of food production problems is proposed. Most plant species (including the major crops in the tropics) form beneficial associations with arbuscular mycorrhizal (AM) fungi. These fungi could be the most important and poorly understood resource for nutrient acquisition and plant growth in agriculture. This review treats the role of AM fungi in enhancing physical, chemical, and biological soil quality. It focuses on the roles of AM in maintenance and improvement of soil structure, the uptake of relatively immobile elements, both macronutrients (phosphorus) and micronutrients (zinc), the alleviation of aluminium and manganese toxicity, the interactions with other beneficial soil organisms (nitrogen-fixing rhizobia), and improved protection against pathogens. Mycorrhizal associations enable a better use of sparingly soluble phosphorus pools, thereby increasing the efficiency of added phosphorus fertilizer and of the large relatively immobile phosphorus pools. Mycorrhizal management through agroforestry, reduced soil disturbance or crop rotation, is often a better option than mycorrhizal inoculation, considering the problems and costs of large-scale inoculum production. Research directions that are needed to increase understanding of mycorrhizal associations in tropical cropping systems and to increase mycorrhizal benefit are indicated. [Copyright &y& Elsevier]

• The aim here was to separately assess mycorrhizal fungal and plant responses under elevated atmospheric CO2, and to test a mycocentric model that assumes that increased carbon availability to the fungus will not automatically feed back to enhanced plant growth performance. • Meta-analyses were applied across independent studies. Responses were compared in ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) fungi, and ECM and AM plants. • Responses of both mycorrhizal fungi and mycorrhizal plants to elevated CO2 were significantly positive. The response ratio for ECM fungi was 1.34 (an increase of 34%) and for AM fungi 1.21 (21%), indicating a significantly different response. The response ratio for ECM plants was 1.26, similar to that of AM plants (1.25). Fractional colonization proved to be an unsuitable fungal parameter. Evidence was found for the mycocentric view in ECM, but not in AM systems. • Fungal identity and plant identity were important parameters that affected response ratios. The need for better descriptors of fungal and plant responses is emphasized. New Phytologist (2005) doi: 10.1111/j.1469-8137.2005.01458.x © New Phytologist (2005) [ABSTRACT FROM AUTHOR]

Discusses a study which reconstructed the evolution of partial incompatibility in the Hebeloma crustuliniforme aggregate. Materials and methods; Results; Discussion.

The authors discuss research on the performance of trees associating with ectomycorrhizal fungi. The study explores the inability of trees to eliminate their mycorrhizal fungal partners in cases where a nonmycorrhizal habit would be more beneficial. The authors indicate that the model employed by researchers predicts the existence of two stability regimes of ectomycorrhizal symbioses and a strong coupling between nitrogen retention and ectomycorrhizal fungi.

Describes a molecular method for identifying hyphae of ectomycorrhizal fungi. Amplification of fungal DNA; Identification of several fungi using the terminal restriction fragment length polymorphism method; Correlation of data on niche differentiation with data on the relative importance of the various fungi in the different layers.

Summary: Recent studies show that the variation in root functional traits can be explained by a two‐dimensional trait framework, containing a 'collaboration' axis in addition to the classical fast–slow 'conservation' axis. This collaboration axis spans from thin and highly branched roots that employ a 'do‐it‐yourself' strategy to thick and sparsely branched roots that 'outsource' nutrient uptake to symbiotic arbuscular mycorrhizal fungi (AMF).Here, we explore the functionality of this collaboration axis by quantifying how interactions with AMF change the impact of root traits on plant performance. To this end, we developed a novel functional–structural plant (FSP) modelling approach that simulates plants competing for light and nutrients in the presence or absence of AMF.Our simulation results support the notion that in the absence of AMF, plants rely on thin, highly branched roots for their nutrient uptake. The presence of AMF, however, promotes thick, unbranched roots as an alternative strategy for uptake of immobile phosphorus, but not for mobile nitrogen.This provides further support for a root trait framework that accommodates for the interactive effect of roots and AMF. Our modelling study offers unique opportunities to incorporate soil microbial interactions into root functionality as it integrates consequences of belowground trait expression. [ABSTRACT FROM AUTHOR]

Plant biomass conversion by saprotrophic fungi plays a pivotal role in terrestrial carbon (C) cycling. The general consensus is that fungi metabolize carbohydrates, while lignin is only degraded and mineralized to CO2. Recent research, however, demonstrated fungal conversion of 13C-monoaromatic compounds into proteinogenic amino acids. To unambiguously prove that polymeric lignin is not merely degraded, but also metabolized, carefully isolated 13C-labeled lignin served as substrate for Agaricus bisporus, the world's most consumed mushroom. The fungus formed a dense mycelial network, secreted lignin-active enzymes, depolymerized, and removed lignin. With a lignin carbon use efficiency of 0.14 (g/g) and fungal biomass enrichment in 13C, we demonstrate that A. bisporus assimilated and further metabolized lignin when offered as C-source. Amino acids were high in 13C-enrichment, while fungal-derived carbohydrates, fatty acids, and ergosterol showed traces of 13C. These results hint at lignin conversion via aromatic ring-cleaved intermediates to central metabolites, underlining lignin's metabolic value for fungi. [ABSTRACT FROM AUTHOR]

The authors discuss aspects of mycorrhizal symbiosis that affect the inorganic nutrient cycling and the proposed field testing using the mycorrhizal-associated nutrient economy (MANE) framework. They compare the studies of Phillips et al. and Rosling et al. by testing the arbuscular mycorrhizal trees to distinguish the dominant type of mycorrhizal association. The authors think that Rosling et al. provide relevant mycorrhizal research for ectomycorrhizal and arbuscular mycorrhizal trees.

Soil microbes are directly involved in soil organic carbon (SOC) decomposition, yet the importance of microbial biodiversity in regulating the temperature sensitivity of SOC decomposition remains elusive, particularly in alpine regions where climate change is predicted to strongly affect SOC dynamics and ecosystem stability. Here we collected topsoil and subsoil samples along an elevational gradient on the southeastern Tibetan Plateau to explore the temperature sensitivity (Q10) of SOC decomposition in relation to changes in microbial communities. Specifically, we tested whether the decomposition of SOC would be more sensitive to warming when microbial diversity is low. The estimated Q10 value ranged from 1.28 to 1.68, and 1.80 to 2.10 in the topsoil and subsoil, respectively. The highest Q10 value was observed at the lowest altitude of forests in the topsoil, and at the highest altitude of alpine meadow in the subsoil. Variations in Q10 were closely related to changes in microbial properties. In the topsoil the ratio of gram‐positive to gram‐negative bacteria (G+:G−) was the predominant factor associated with the altitudinal variations in Q10. In the subsoil, SOC decomposition showed more resilience to warming when the diversity of soil bacteria (both whole community and major groups) and fungi was higher. Our results partly support the positive biodiversity‐ecosystem stability hypothesis. Structural equation modeling further indicates that variations in Q10 in the subsoil were directly related to changes in microbial diversity and community composition, which were affected by soil pH. Collectively our results provide compelling evidence that microbial biodiversity plays an important role in stabilizing SOC decomposition in the subsoil of alpine montane ecosystems. Conservation of belowground biodiversity is therefore of great importance in maintaining the stability of ecosystem processes under climate change in high‐elevation regions of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Soil salinity affects soil quality and reduces plant performance. Arbuscular mycorrhizal fungi (AMF) can enhance the tolerance of plants under salinity stress. Cultivation of eucalyptus (Eucalyptus camaldulensis), which exhibits high water use efficiency, is possible in saline areas to produce raw materials for the pulp industry. We determined the effects of arbuscular mycorrhizal fungi (AMF) on the growth and survival of eucalyptus seedlings under saline conditions. Three different clones of eucalyptus seedlings were pre-inoculated with three salt-tolerant AMF species, namely Glomus sp.2, Gigaspora albida and G. decipiens, and without pre-inoculation. The seedlings were grown in a greenhouse for 45 days. They were then transferred to individual pots, filled with field soil and subsequently treated with NaCl solution until electro-conductivity (EC) reached 10, 15 and 20 dS m−1. They were watered for 90 days under nursery conditions. The results show that increased salinity levels reduced plant performance, fractional AMF root colonization, spore number, and eucalypt K/Na ratio. AMF significantly increased chlorophyll and decreased leaf proline concentrations by more than 50% and 20% respectively and increased the K/Na ratio three- to six-fold compared with non-inoculated plants. Pre-inoculation with AMF before outplanting also improved plant performance by more than 30% under salinity stress compared to non-inoculated plants. We conclude that AMF can alleviate the negative impacts of salinity on plant physiological and biochemical parameters. [ABSTRACT FROM AUTHOR]

A new saprotrophic species was discovered during our fungal inventory at the Boston Harbor Islands National Recreation Area (Massachusetts), which consists of 34 islands and peninsulas. Simocybe ramosa sp. nov. (Agaricales, Crepidotaceae) is described based on morphology and molecular phylogenetic data. The holotype collection was found in a Quercus (oak)–Carya (hickory) forest under bark of a dead oak tree on World's End peninsula, the largest land mass of the archipelago. Phylogenetic reconstruction of a dataset of the internal transcribed spacer region (ITS) resolved S. ramosa and S. rhabarbarina as sister species. Simocybe rhabarbarina is here redescribed based on the holotype and newly reported material from the Netherlands, and its presence on the island of Jersey, off the coast of northern France, is confirmed based on an ITS sequence. Finally, we compare morphological features of S. ramosa with S. rhabarbarina and the 20 species in the genus that have thus far been recorded in Canada, the US, and Mexico. [ABSTRACT FROM AUTHOR]

The author discusses the study conducted by L. Tedersoo and colleagues which describes enzyme activities and stable isotope patterns of ectomycorrhizas in Gabon rainforest. The author says that the study showed the potential enzyme activities and nitrogen (N) natural abundance of individual root tips were not correlated. He mentions that M. Buée and colleagues note that enzyme assay measures activity in a buffer solution that at the water soil potential.

Summary: Recent studies on root traits have shown that there are two axes explaining trait variation belowground: the collaboration axis with mycorrhizal partners and the conservation ('fast – slow') axis. However, it is yet unknown whether these trait axes affect the assembly of soilborne fungi. We expect saprotrophic fungi to link to the conservation axis of root traits, whereas pathogenic and arbuscular mycorrhizal fungi link to the collaboration axis, but in opposite directions, as arbuscular mycorrhizal fungi might provide pathogen protection.To test these hypotheses, we sequenced rhizosphere fungal communities and measured root traits in monocultures of 25 grassland plant species, differing in age. Within the fungal guilds, we evaluated fungal species richness, relative abundance and community composition.Contrary to our hypotheses, fungal diversity and relative abundance were not strongly related to the root trait axes. However, saprotrophic fungal community composition was affected by the conservation gradient and pathogenic community composition by the collaboration gradient. The rhizosphere AMF community composition did not change along the collaboration gradient, even though the root trait axis was in line with the root mycorrhizal colonization rate.Overall, our results indicate that in the long term, the root trait axes are linked with fungal community composition. [ABSTRACT FROM AUTHOR]

There is an increasing interest in finding eco-friendly and safe approaches to increase agricultural productivity and deliver healthy foods. Arbuscular mycorrhizal fungi (AMF) and endophytic fungi (EPF) are important components of sustainable agriculture in view of their ability to increase productivity and various plant secondary metabolites with health-promoting effects. In a pot experiment, our main research question was to evaluate the additive and synergistic effects of an AMF and four root-endophytic fungi on plant performance and on the accumulation of health-promoting secondary compounds. Plant growth varied between the treatments with both single inoculants and co-inoculation of an AMF and four EPF strains. We found that inoculation with a single EPF positively affected the growth and biomass production of most of the plant-endophyte consortia examined. The introduction of AMF into this experiment (dual inoculation) had a beneficial effect on plant growth and yield. AMF, Rhizophagus variabilis KS-02 co-inoculated with EPF, Trichoderma zelobreve PBMP16 increased the highest biomass, exceeding the growth rate of non-inoculated plants. Co-inoculated R. variabilis KS-02 and T. zelobreve PBMP16 had significantly greater beneficial effects on almost all aspects of plant growth, photosynthesis-related parameters, and yield. It also promoted root growth quality and plant nutrient uptake. The phenolic compounds, anthocyanin, and antioxidant capacity in rice seeds harvested from plants co-inoculated with AMF and EPF were dramatically increased compared with those from non-inoculated plants. In conclusion, our results indicated that EPF and AMF contributed to symbiosis in Maled Phai cultivar and were coordinately involved in promoting plant growth performance under a pot trial. [ABSTRACT FROM AUTHOR]

Municipal waste is usually composted with an N-rich substrate, such as manure, to increase the N content of the product. This means that a significant amount of nitrogen can be lost during composting. The objectives of this study were (i) to investigate the effect of split addition of a nitrogen-rich substrate (poultry manure) on nitrogen losses and greenhouse gas emissions during composting and to link this effect to different bulking agents (coffee husks and sawdust), and (ii) to assess the effect of split addition of a nitrogen-rich substrate on compost stability and sanitisation. The results showed that split addition of the nitrogen-rich substrate reduced nitrogen losses by 9% when sawdust was used and 20% when coffee husks were used as the bulking agent. Depending on the bulking agent used, split addition increased cumulative N 2 O emissions by 400–600% compared to single addition. In contrast, single addition increased methane emissions by up to 50% compared to split addition of the substrate. Hence, the timing of the addition of the N-rich substrate had only a marginal effect on total non-CO 2 greenhouse gas emissions. Split addition of the N-rich substrate resulted in compost that was just as stable and effective at completely eradicating weed seeds as single addition. These findings therefore show that split addition of a nitrogen-rich substrate could be an option for increasing the fertilising value of municipal waste compost without having a significant effect on total greenhouse gas emissions or compost stability. [ABSTRACT FROM AUTHOR]

Black rice (Oryza sativa L.) contains high concentrations of bioactive compounds that are associated with human-health benefits. Arbuscular mycorrhizal fungi (AMF) can increase plant performance and concentrations of these bioactive compounds. In a pot experiment, the effects of four different species of AMF (Claroideoglomus etunicatum; Rhizophagus variabilis; Rhizophagus nov. spec.; Acaulospora longula) were assessed on growth performance, grain yield, concentrations of phenolic compounds and anthocyanin, and antioxidant activity of two black-rice cultivars. The experiment was a completely randomized factorial design with two factors, viz. cultivar (Niew Dam Hmong and Maled Phai) and treatment (four different species of AMF and two non-inoculated treatments, without and with mineral fertilizer). Results showed that cultivar, treatment, and their interaction were almost always significant sources of variation for both plant performance parameters and concentrations of bioactive compounds. Maled Phai showed higher performance and higher concentrations of phenolics and anthocyanins but lower antioxidant activity than Niew Dam Hmong. The non-inoculated treatment without mineral fertilizer showed the lowest performance. The non-inoculated treatment with mineral fertilizer resulted in larger root and shoot biomass than the mycorrhizal treatments, but grain yield was higher in the mycorrhizal treatments. Inoculation with R. variabilis resulted in the highest concentration of phenolics and anthocyanins. We conclude that R. variabilis was the best inoculum for increasing grain yield and bioactive compounds, especially in Maled Phai. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study is to improve our understanding of soil organic matter (SOM) stability in Brazilian Cerrado, by interpreting soil properties at the ecosystem scale and elaborating on the interactions of biotic, climatic and edaphic controls. Methods: Three 2 m soil profiles with significantly different total organic carbon TOC content but located on the same geomorphological unit were studied for δ13C isotopic composition to connect tree-grass patterns to TOC content. To gain insight into soil carbon stability, C/N, δ13C and δ15N were analysed for functional organic matter (OM) pools: free particulate OM (POM), occluded POM, base-extractable OM, and mineral-associated OM. Results: Small but abrupt shifts of δ13C with depth reflected simultaneous changes in tree-grass vegetation patterns over the past 10,000 years in all three profiles. These temporal changes were superimposed on spatial differences as indicated by consistent differences in δ13C values between the profiles, reflecting that site-specific differences in tree-grass patterns persisted over the past 10,000 years. Profiles with a historically larger contribution from trees (as evidenced by lower δ13C) had increased charcoal contents. Downward movement of charcoal by intense bioturbation occurred faster in the OM-rich soils as suggested by 14C dating. Conclusion: We found that long-term carbon storage in Brazilian Cerrado soils was a conjunction of wildfires, bioturbation, and local edaphic controls on tree-grass composition. Soils with an OM-rich thick A-horizon had more trees, more charcoal, and a higher activity of soil macrofauna, which was related to local differences in soil water availability. [ABSTRACT FROM AUTHOR]

Questions Secondary succession in the tropics can follow alternative pathways. Land-use history is known to engender alternative successional communities, but the underlying mechanisms driving and sustaining divergence remain unclear. In this study we aim to answer the following questions: (1) does previous land use act as a filter for species composition in secondary forests; and (2) what are the relative roles of management practices, soil properties and landscape composition in determining species composition? Location Central Amazon, Brazil. Methods We sampled trees, shrubs and palms (≥1cm diameter) in 38 early secondary forests (5 yr after abandonment) located along gradients of land-use intensity in five shifting cultivation landscapes. We measured the diameter and height of each sampled plant, identified it to species or morpho-species level and checked if it was resprouting or not. At each secondary forest we also collected soil samples for chemical and physical analyses and estimated the amount of old-growth forest surrounding it (landscape composition). Results We found that previous land-use intensity determined species composition. With increasing land-use intensity, management practices of cut-and-burn and associated reduction in soil quality filtered out seed-dependent species and favoured strong sprouters and species that can cope with low nutrient availability. Landscape composition had a weak effect on species assemblages. We found specific species assemblages and indicator species associated with different levels of previous land-use intensity. As a consequence of these local filters, species α- and β-diversity decreased and therefore early successional communities became more similar to each other. Conclusion Species composition of successional forests is strongly determined by different land-use intensities. Dispersal limitation has a limited effect on determining the composition of the dominant species. Filtering effects of management practices and soil quality determine the species dominating the canopy at early stages of succession and narrow down the range of species able to colonize and establish. This study highlights how land use shapes successional communities and suggests that alternative successional pathways are determined at early stages of succession. Therefore, accounting for land-use history is crucial to improve the understanding of tropical secondary succession. We present a list of indicator species for different levels of previous land-use intensity that can be used to support conservation and restoration decisions in the Amazon. [ABSTRACT FROM AUTHOR]

Recent global warming affects species compositions at an unprecedented rate. To predict climate‐induced changes in species assemblages, a better understanding of the link between species occurrence and climate is needed. Macrofungal fruit body assemblages are correlated with the thermal environment at the European scale. However, it is still unknown whether macrofungal communities are also phylogenetically structured by thermal environments. Thermal environments are characterized by annual temperature means but also by intra‐annual temperature variability (hereafter termed temperature seasonality), which are both considered in this study. Here, we used distribution data of 2882 species based on fruit body records across Europe to address two main questions: 1) are mushroom assemblages at the extremes of the mean (warm and cold) and seasonal (high intra‐annual variability, i.e. continental) climate gradient phylogenetically more similar than expected (phylogenetic alpha diversity); 2) are mushroom assemblages, that are subject to different mean and seasonal temperature conditions, composed of different lineages (phylogenetic beta diversity). Our phylogenetic alpha diversity analysis shows that mushroom assemblages are phylogenetically structured by warm and cold environments, indicating that phylogenetically related species with similar traits thrive under more extreme conditions. In contrast, assemblages are phylogenetically more dissimilar (overdispersed) in temperature seasonal environments, indicating limiting similarity. Phylogenetic beta diversity was significantly correlated with mean and seasonal temperature differences, a response mainly driven by a few genera. Our results show that macrofungal assemblages are phylogenetically structured by temperature across Europe, suggesting phylogenetically constrained specialization towards temperature extremes. Predicted anthropogenic warming is likely to affect species composition and phylogenetic diversity with additional consequences for the carbon‐ and nutrient cycles. [ABSTRACT FROM AUTHOR]

Peatlands are archives of environmental change that can be driven by climate and human activity. Proxies for peatland vegetation composition provide records of (local) environmental conditions that can be linked to both autogenic and allogenic factors. Analytical pyrolysis offers a molecular fingerprint of peat, and thereby a suite of environmental proxies. Here we investigate analytical pyrolysis as a method for biomarker analysis. Pyrolysates of 48 peatland plant species were compared, comprising seventeen lichens, three Sphagnum species, four non- Sphagnum mosses, eleven graminoids (Cyperaceae, Juncaceae, Poaceae), five Ericaceae and six species from other families. This resulted in twenty-one potential biomarkers, including new markers for lichens (3-methoxy-5-methylphenol) and graminoids (ferulic acid methyl ester). The potential of the identified biomarkers to reconstruct vegetation composition is discussed according to their depth records in cores from six peatlands from boreal, temperate and tropical biomes. The occurrence of markers for Sphagnum , graminoids and lichens in all six studied peat deposits indicates that they persist in peat of thousands of years old, in different vegetation types and under different conditions. In order to facilitate the quantification of biomarkers from pyrolysates, typically expressed as proportion (%) of the total quantified pyrolysis products, an internal standard (5-α-androstane) was introduced. Depth records of the Sphagnum marker 4-isopropenylphenol from the upper 3 m of a Sphagnum -dominated peat, from samples analysed with and without internal standard showed a strong positive correlation (r 2 = 0.72, P < 0.0005, n = 12). This indicates that application of an internal standard is a reliable method to assess biomarker depth records, which enormously facilitates the use of analytical pyrolysis in biomarker research by avoiding quantification of a high number of products. [ABSTRACT FROM AUTHOR]

1. Understanding how land-use intensification affects forest resilience is a key for elucidating the mechanisms underlying regeneration processes and for planning more sustainable land-use systems. Here, we evaluate how the intensification of a swidden cultivation system affects secondary-forest resilience in the Amazon. 2. Along a gradient of land-use intensity, we analysed the relative role of management intensity, soil properties and landscape configuration in determining the resilience of early secondary forests (SFs). We assessed resilience as the recovery level of forest structure and species diversity achieved by SFs 5 years after abandonment. We used as a reference the recovery level achieved by SFs subjected to the lowest intensity of use, given that these SFs are part of a dynamic system and may not develop to old-growth forests. Therefore, we interpreted a deviation from this reference level as a change in forest resilience. 3. The recovery of forest structure was determined by management intensity, while the recovery of species diversity was driven by landscape configuration. With increasing number of cycles and weeding frequency along with decreasing fallow period and patch area, SF basal area and canopy height decreased, regeneration shifted from a seed- to sprout-dependent strategy, and liana infestation on trees increased. With decreasing area covered by old-growth forest, species richness and Shannon diversity decreased. 4. Secondary-forest resilience decreased with land-use intensification, mainly mediated by the effect of management intensity upon regeneration strategies. Our findings demonstrate the - many times overlooked - importance of previous management intensity in determining the structure of SFs and highlight the importance of regeneration strategy for forest resilience. 5. Synthesis. Swidden cultivation supports people's livelihoods and transforms landscapes in the tropics. The sustainability of this system depends on ecosystem services provided by SFs that develop during the fallow period. Land-use intensification reduces the resilience of SFs and ultimately may drive the system towards an arrested succession state that holds a lower potential to deliver ecosystem services to the Amazonian people. Under an intensification scenario, the adaptation of management practices is needed to guarantee the resilience of swidden cultivation systems. [ABSTRACT FROM AUTHOR]

Most knowledge about the degradation of lignocellulose in natural environments is based on woody tissue and aerobic systems; however, in peatlands the contribution of graminoids to organic matter (OM) is often significant and anaerobic conditions prevail. In order to reconstruct past environmental conditions from peatlands and predict possible feedback mechanism between peatlands and climate change, a better understanding of the decomposition of graminoid tissue and the effects of anaerobic conditions on decomposition are needed. Samples (51) from the upper 1 m of the graminoid-dominated Penido Vello peatland (Xistral Mountains, Galicia, NW Spain) were analysed with pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) and 13 C cross polarisation magic angle spinning nuclear magnetic resonance spectroscopy ( 13 C CPMAS NMR). Carbon and nitrogen contents were also determined. Depth profiles of molecular groups identified using 13 C CPMAS NMR were consistent with those of depth-related distributions of quantified pyrolysis products (aliphatics, polysaccharides and aromatics). Molecular proxies were selected from peat pyrolysates to reflect the state of decay of 1) lignocellulose (the summed lignin and polysaccharide pyrolysis products, Lg and Ps, respectively), 2) lignified cellulose (levoglucosan/Ps) and hemicellulose (4-hydroxy-5,6-dihydro-(2 H )-pyran-2-one/Ps), 3) macromolecular lignin including syringyl (S), guaiacyl (G) and p -hydroxyphenyl (H) ratios (S/G; H/(S + G), and side chain oxidation and shortening (vanillic acid/G, syringic acid/S, 4-acetylguaiacol/G, 4-acetylsyringol/S, C 3 -guaicols/G and C 3 -syringols/S) and 4) non-lignin phenolic acids (4-vinylphenol/H, 4-vinylguaiacol/G). Factor analysis was applied to these proxies and 120 quantified pyrolysis products to examine the influence of possible underlying factors that could explain the observed variation. Botanical changes and several degradation stages including surface decay (both aerobic and anaerobic), aerobic sub-surface decay and depth related decay (long-term anaerobic) were identified with factor analysis and all affected the variance of lignin-based decomposition proxies. The net effect of these environmental factors on the lignin proxies was examined using their depth records. This revealed that some lignin decomposition proxies were not in agreement with the literature: 1) G and S moieties with a C 3 alkyl side chain showed no correlation with bog hydrology at the time of peat formation; 2) G and S moieties with acetyl side chains were related to both relatively dry (secondary aerobic decay) and wet (first stage of decay) conditions; 3) vanillic acid and syringic acid were related partly to ericoids (indicating dry conditions) and partly to free phenolic acids (less depleted under wet conditions); and 4) preferential decay of G over S moieties was found during the first stage of decay (both aerobic and anaerobic) and long-term anaerobic decay. These contradictions can be explained by the dominance of non-woody lignin sources (graminoids) and the prominence of anaerobic decay in peatlands. Our findings indicate that the effect of anaerobic decay and source vegetation should be considered when using lignin proxies to deduce aerobic decay in peat records. [ABSTRACT FROM AUTHOR]

Efforts are being made globally to promote transformations from conventional to agroecological agricultural systems. In many places, such efforts have been made in dialogue with peasant communities, involving a range of social actors with converging actions. Understanding the drivers of such transformations can elucidate key elements capable of promoting changes in the agrifood system. Was to identify and comprehend the drivers of agroecological transition and their capacity to transform the agricultural system, based on the analysis of the experience in the Zona da Mata of Minas Gerais, Brazil, where such a process has been built since the early 1980's, involving different institutions and scales of transformation. We analyzed and integrated the results of four PhD theses, carried out semi-structured interviews with different social actors regarding the transition in its social, environmental, and institutional aspects, and engaged in participant observation. 29 drivers were identified that promote agroecology by creating conditions and motivating peasants to switch from conventional to agroecological agriculture. These drivers act synergistically in the ecological, social, cultural, political, and economic dimensions. One crucial synergy is the combination of political support with bottom-up movements. The analysis of the drivers contributes to broadening the agroecological transition process. The research is innovative by demonstrating that the analysis of drivers for agroecological transitions must be based on concrete experiences in the territories, the dimensions involved, the classification of the driver, the internal and external conditions of the peasant units that interfere in the transition process, and the impacts of the agroecological transition process for peasant families. Specifically, the articulation among cosmovision and identity, collective knowledge building, organizations at regional and national levels, political engagement, and nature-based technical solutions led countless families to promote and practice agroecology. [Display omitted] • Social organization at different scales must converge into actions in favor of the agroecological transition. • Land access, social organization of labor, cultural meanings, environmental context, and cocreation of knowledges are fundamental to agroecological transition. • Women and youths play key roles in the agroecological transition. • Public land use planning affects landscape transformations and the agroecological transition. • Agroecological public policy combined with a political bottom-up movement are essential for the transition. [ABSTRACT FROM AUTHOR]

Grassland ecosystems worldwide not only provide many important ecosystem services but they also function as a major source of the greenhouse gas nitrous oxide ( N2O), especially in response to nitrogen deposition by grazing animals. To explore the role of plants as mediators of these emissions, we tested whether and how N2O emissions are dependent on grass species richness and/or specific grass species composition in the absence and presence of urine deposition. We hypothesized that: (i) N2O emissions relate negatively to plant productivity; (ii) four-species mixtures have lower emissions than monocultures (as they are expected to be more productive); (iii) emissions are lowest in combinations of species with diverging root morphology and high root biomass; and (iv) the identity of the key species that reduce N2O emissions is dependent on urine deposition. We established monocultures and two- and four-species mixtures of common grass species with diverging functional traits: Lolium perenne L. (Lp), Festuca arundinacea Schreb. (Fa), Phleum pratense L. (Php) and Poa trivialis L. (Pt), and quantified N2O emissions for 42 days. We found no relation between plant species richness and N2O emissions. However, N2O emissions were significantly reduced in specific plant species combinations. In the absence of urine, plant communities of Fa+Php acted as a sink for N2O, whereas the monocultures of these species constituted a N2O source. With urine application Lp+Pt plant communities reduced ( P < 0.001) N2O emissions by 44% compared to monocultures of Lp. Reductions in N2O emissions by species mixtures could be explained by total biomass productivity and by complementarity in root morphology. This study shows that plant species composition is a key component underlying N2O emissions from grassland ecosystems. Selection of specific grass species combinations in the context of the expected nitrogen deposition regimes may therefore provide a key for mitigation of N2O emissions. [ABSTRACT FROM AUTHOR]