Forest tree growth is linked to mycorrhizal fungal composition and function across Europe

Most trees form symbioses with ectomycorrhizal fungi (EMF) which influence access to growth-limiting soil resources. Mesocosm experiments repeatedly show that EMF species differentially affect plant development, yet whether these effects ripple up to influence the growth of entire forests remains unknown. Here we tested the effects of EMF composition and functional genes relative to variation in well-known drivers of tree growth by combining paired molecular EMF surveys with high-resolution forest inventory data across 15 European countries. We show that EMF composition was linked to a three-fold difference in tree growth rate even when controlling for the primary abiotic drivers of tree growth. Fast tree growth was associated with EMF communities harboring high inorganic but low organic nitrogen acquisition gene proportions and EMF which form contact versus medium-distance fringe exploration types. These findings suggest that EMF composition is a strong bio-indicator of underlying drivers of tree growth and/or that variation of forest EMF communities causes differences in tree growth. While it may be too early to assign causality or directionality, our study is one of the first to link fine-scale variation within a key component of the forest microbiome to ecosystem functioning at a continental scale

Belowground Biodiversity Relates Positively to Ecosystem Services of European Forests

Environmental Biolog

Scoping future research for air pollution recovery indicators (APRI). (Workshop report)

Atmospheric nitrogen (N) pollution is a major and ongoing cause of biodiversity loss across the UK, but in some locations N pollution pressures have been declining. In response to these dynamics, JNCC requested a workshop to help to scope Phase 2 of the Air Pollution Recovery Indicators (APRI) project. The damaging effects of excess N load and of gaseous ammonia on many ecosystems are clear. However, the processes and timescales of ecosystem recovery following a decrease in pollution pressure are less well understood. The APRI project aims to take practical steps to fill this knowledge gap by delivering new scientific research focused on indicators of ecosystem and species recovery from N pollution. In Phase 1, predominantly below-ground responses are being studied at a dry heathland site where experimental additions of N were made between 1998 and 2011, revealing lingering effects on soil chemistry, the soil fungi community and vegetation structure (Kowal et al. 2024). The effect on mycorrhizal fungi, and using these fungi as recovery indicators, is being examined in more detail with recently established assessment methods (Arrigoni et al. 2023). Phase 2 of APRI will consider recovery from N impacts more broadly, e.g. by studying other habitats or species. Further empirical research may be commissioned to better understand recovery pathways from air pollution. A workshop was held on 7–8 November 2023 to help develop an action plan for the remainder of the APRI project. This report summarises the workshop discussion and ensuing work. We note that the focus of the APRI project is on assessing recovery. It is therefore essential to contrast responses of ecosystems subject to decreased pollution pressure with indicators from ecosystems experiencing ongoing pollution. Properties that have been used previously to assess impacts can be used to understand recovery, and novel indicators of ecosystem change are also likely to be useful for assessing recovery. Whatever indicators are chosen to assess change, benchmarking data will be needed to assess the range of potential values and relationships with N deposition. Results from the workshop and subsequent discussions include: • Eleven criteria to help choose appropriate indicators in relation to declining N deposition: Speed of response, Sensitivity of response, Specificity of response, Generality to multiple habitats, Relatedness to recovery endpoints, Previous use, Breadth of pollution gradient, Added value to other policy areas, Resilience in face of anticipated change, Feasibility of collection, Measurement uncertainty. • The need to consider a basket of indicators to indicate recovery from N pollution. Such a basket could include examples from different categories e.g. indicators of pressure, biogeochemical response indicators, and biotic response indicators, with individual indicators likely responding over different timescales. The exact choice may depend on the habitat concerned and the availability of prior data, as well as the question being posed and/or policy goal. • Explicit recommendations on sites to target in APRI Phase 2 to gain information on recovery indicator trajectories, namely (i) well-designed field experiments where N addition has ceased, and (ii) point sources of emissions that have ceased to operate, preferably with a super-imposition of an experimental treatment or treatments. Given uncertainties associated with modelled historical, contemporary, and future N deposition and the potential for confounding variables, analysing survey data from across the UK will be unlikely to provide robust information within the timeframes of the APRI Phase 2. We recommend further assessments may help develop detailed plans for empirical work in Phase 2 of APRI. Potential next steps are to: • Finalise a list of potential and priority indicators of recovery from air pollution (which may differ by habitat type), specifically from high levels of N deposition and/or high atmospheric reactive N concentrations. This finalisation could be done through active participation of the air pollution community and the completion of ‘live’ spreadsheets that address potential indicator criteria. • Summarise relevant data on recovery indicators, across key semi-natural habitats. This summary should include data available from other countries with similar environmental contexts, to help disentangle drivers of change in the UK context. This evidence will help understand recovery pathways from air pollution. As above, this could be done through the active participation of the air pollution community and the completion of ‘live’ spreadsheets. Such an approach could also enable gap analyses, for example identifying where we are missing information by habitat and/or environmental conditions. • Identify areas where co-located monitoring of N with existing habitat/species monitoring could enhance the likelihood for establishing recovery indicators. This should enhance other similar activity such as through the Natural Capital and Ecosystem Assessment programme and the UK Air Pollution Impacts on Ecosystems Networks (APIENs). • Develop a list of priority habitats and sites where empirical research is needed to better understand recovery pathways, including a gap analysis of habitats, methods and/or indicators. • Encourage activities that enhance understanding of ammonia emission sources at local scale (e.g. 1 km or less), to help better identify areas where N pollution has decreased, and recovery might be detected. This could include intensive monitoring or collating and sharing information about permitted N sources. • Develop case studies, including potentially from APRI Phase 1, to demonstrate how existing evidence on localised recovery in semi-natural habitats of conservation importance can be used by policy- and decision-makers to help drive policy toward continued reductions in emissions of reactive N

Testing the relative sensitivity of 102 ecological variables as indicators of woodland condition in the New Forest, UK.

Forests globally are facing an increasing number of threats from modified disturbance regimes, novel stressors and changing environmental conditions. This has ultimately resulted in declines in the ecological condition of many forest and woodland ecosystems, leading to widespread tree mortality and stand dieback. Effective indicators of overall woodland ecological condition are therefore needed for environmental monitoring and to support management responses. To test the effectiveness of different variables that could potentially be used as indicators of woodland condition, 102 variables that describe woodland structure, composition, functioning, edaphic conditions and disturbance regimes were assessed along 12 replicate gradients of beech stand dieback. Results indicated that 35 variables differed significantly between at least two stages of the dieback gradient, indicating their sensitivity to stand dieback. Seven of these indicators related to woodland species composition, two to functional processes, 20 to structural features, four to edaphic conditions, and two to disturbance regimes. These results demonstrate that effective indicators can potentially be identified for each of the ecological categories. Effective composition indicators included species richness of ectomycorrhizal fungi, ground flora and epiphytic lichens; functional indicators were soil respiration rate and net nitrification rate; edaphic conditions included soil Na:Ca ratio, exchangeable sodium, total carbon, Ca:Al ratio; structural indicators included canopy openness, litter cover, sward height, and volume of deadwood, and for disturbance the indicator was Equus dung density. Other measures, such as shrub cover and species richness of carabid beetles and spiders, were not found to vary significantly along the dieback gradients, and were therefore not identified as effective indicators. These results demonstrate the value of gradient analysis for evaluating indicators of woodland condition, but also highlight the need for multi-site studies to identify indicators with widescale applicability

Mycorrhization of fagaceae forests within mediterranean ecosystems

Mediterranean Fagaceae forests are valuable due to their ecological and socioeconomic aspects. Some profitable plant species, such as Castanea (timber and chestnut), Quercus (timber and cork), and Fagus (timber), encounter in this habitat the excellent edaphoclimatic conditions to develop. All Fagaceae plants are commonly associated to ECM fungal species, which are found in these forests in quite stable communities, mainly enriched in Russulaceae and Telephoraceae species. Currently, the Mediterranean Basin is considered as one of the global biodiversity hotspots, since many of their endemic plant species are not found elsewhere and are now under threat. Due to climate changing and introduction of disease agents, Fagaceae forests are facing an adaptation challenge to both biotic and abiotic threats. Although ECM communities are highly disturbed by climate factors and tree disease incidence, they could play an important role in increasing water availability to the plant and also improving plant tree defense against pathogens. Recent advances, namely, on genomics and transcriptomics, are providing tools for increasing the understanding of Fagaceae mycorrhization process and stress responses to biotic and abiotic stresses. Such studies can provide new information for the implementation of the most adequate management policies for protecting threaten Mediterranean forests.info:eu-repo/semantics/publishedVersio

State of the world’s plants and fungi 2020

Kew’s State of the World’s Plants and Fungi project provides assessments of our current knowledge of the diversity of plants and fungi on Earth, the global threats that they face, and the policies to safeguard them. Produced in conjunction with an international scientific symposium, Kew’s State of the World’s Plants and Fungi sets an important international standard from which we can annually track trends in the global status of plant and fungal diversity