Belowground DNA-based techniques: untangling the network of plant root interactions

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How do plants regulate the function, community structure, and diversity of mycorrhizal fungi?

In many semi-natural and natural ecosystems, mycor-rhizal fungi are the most abundant and functionally important group of soil micro-organisms. They are almost wholly dependent on their host plants to supply them with photosynthate in return for which they en-able the plant to access greater quantities of nutrients. Thus, there is considerable potential for plant commu-nities to regulate the structure and function of mycor-rhizal communities. This paper reviews some of the key recent developments that have enabled the influence of plant species richness, composition, and age on mycorrhizal communities in boreal forests and temperate grassland to be determined. It discusses the emerging evidence that, in some situations, plant species richness is related to mycorrhizal species richness, in contrast to previous thinking. The paper also includes some preliminary data on the effect of host stand age on root-associated basidiomycete communities. It concludes by highlighting some of the new methodological advances that promise to unravel the linkages between mycorrhizal diversity and their function in situ

Soil organic matter distribution and below-ground competition between Calluna vulgaris and Nardus stricta

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Spatial separation of litter decomposition and mycorrhizal nitrogen uptake in a boreal forest.

Our understanding of how saprotrophic and mycorrhizal fungi interact to re-circulate carbon and nutrients from plant litter and soil organic matter is limited by poor understanding of their spatiotemporal dynamics. In order to investigate how different functional groups of fungi contribute to carbon and nitrogen cycling at different stages of decomposition, we studied changes in fungal community composition along vertical profiles through a Pinus sylvestris forest soil. We combined molecular identification methods with 14C dating of the organic matter, analyses of carbon:nitrogen (C:N) ratios and 15N natural abundance measurements. Saprotrophic fungi were primarily confined to relatively recently (< 4 yr) shed litter components on the surface of the forest floor, where organic carbon was mineralized while nitrogen was retained. Mycorrhizal fungi dominated in the underlying, more decomposed litter and humus, where they apparently mobilized N and made it available to their host plants. Our observations show that the degrading and nutrient-mobilizing components of the fungal community are spatially separated. This has important implications for biogeochemical studies of boreal forest ecosystems

Scotland’s Biodiversity Progress to 2020 Aichi targets: Aichi target 13 - Genetic Diversity Maintained - Supplementary Report 2020

As there is no agreed national list of species of socio-economic and/or cultural value for Scotland, we developed a set of criteria for selecting species. These include: • Species prioritised for conservation value • Species identified as being culturally important • Species providing important ecosystem services • Game species • Species collected for food or medicine Using these criteria, we selected 26 species for initial assessment. For each species, we produced a Genetic Scorecard, outlining: • Relevant genetic conservation issues for the species in question • The importance of its genetic diversity on an international scale • An evaluation of the genetic risks facing in situ populations • A statement of confidence in the assessment • The degree to which representation in ex situ collections mitigate against genetic diversity loss. • An overall ‘traffic light’ score of genetic risks and whether current conservation actions are effective Using 2010 as a baseline reference point, the approach assesses contemporary genetic issues, and likely future issues during a 25-year window from the point of assessment. For quantification of levels of risk, we adopted the following framework: • Negligible: No obviously detectable genetic problems occurring or expected over the next 25 years. • Moderate: Moderate genetic problems occurring or expected over the next 25 years; e.g.: - Moderate loss of populations that are likely to contain unique diversity (e.g., resulting in losses of up to 25% of important genetic types / distinct populations); - Clearly observable fitness problems in up to 25% of populations due to low genetic variation and subsequent inbreeding depression; - Marked and clearly observable loss of genetic integrity by hybridisation at up to 25% of populations; - Severe restrictions on regeneration/recruitment/reproduction in many or most populations of long-lived species limiting evolutionary change in the immediate future. • Serious: Serious genetic problems occurring or expected over the next 25 years; e.g.: - Severe loss of populations that are likely to contain unique diversity (e.g., resulting in losses of > 25% of important genetic types / distinct populations); - Loss of any highly divergent endemic lineages that are globally unique; - Strong, clearly observable fitness problems in >25% of populations due to low genetic variation and subsequent inbreeding depression; - Marked and clearly observable loss of genetic integrity by hybridisation at >25% of populations. The assessment is based on expert opinion, using direct genetic data, where available, combined with information on species biology, abundance and distribution. Where no direct genetic data are available, the genetic risk assessment is based on species biology, abundance and distribution