The epiphytic bryophyte community of Atlantic oak woodlands shows clear signs of recovery following the removal of invasive Rhododendron ponticum

Peer reviewedPostprin

Transplanting the leafy liverwort Herbertus hutchinsiae : A suitable conservation tool to maintain oceanic-montane liverwort-rich heath?

Thanks to the relevant landowners and managers for permission to carry out the experiments, Chris Preston for helping to obtain the liverwort distribution records and the distribution map, Gordon Rothero and Dave Horsfield for advice on choosing experimental sites and Alex Douglas for statistical advice. Juliane Geyer’s help with fieldwork was greatly appreciated. This study was made possible by a NERC PhD studentship and financial support from the Royal Botanic Garden Edinburgh and Scottish Natural Heritage.Peer reviewedPostprin

Arbuscular mycorrhizal colonisation increases with host-density in a heathland community

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Fine-scale distribution of pine ectomycorrhizas and their extramatrical mycelium

In order to clarify the functional role of individual ectomycorrhizal (EcM) fungal species in the field, we need to relate their abundance and distribution as mycorrhizas to their abundance and distribution as extramatrical mycelium (EMM). We divided each of four 20 cm × 20 cm × 2 cm slices of pine forest soil into 100 cubes of 2 cm × 2 cm. For each cube, ectomycorrhizas were identified and the presence of EMM of the EcM fungi recorded as ectomycorrhizas was determined by terminal restriction fragment length polymorphism (T-RFLP) analysis of ITS rDNA. Ectomycorrhizas and EMM of seven EcM species were mapped. Spatial segregation of mycorrhizas and EMM was evident and some species produced their EMM in different soil layers from their mycorrhizas. The spatial relationship between mycorrhizas and their EMM generally conformed to their reported exploration types, but EMM of smooth types (e.g. Lactarius rufus) was more frequent than expected. Different EcM fungi foraged at different spatial scales

A method for the direct detection of airborne dispersal in lichens

This paper sets out a novel method to determine dispersal distances in lichens. Direct measurement of dispersal often remains difficult for lichens and other small inconspicuous species because of the need to track microscopic reproductive propagules, which even if they can be captured, cannot be identified using traditional morphological approaches. A low-cost device (<£200) was developed in order to trap the reproductive propagules of lichens, capable of sampling around 0.1m3 of air per minute. In parallel, molecular techniques were developed to enable species specific detection of propagules caught by the devices, with identification using novel species-specific primers and optimization of a standard DNA extraction and nested PCR protocol. The methods were tested for both their sensitivity and specificity against a suite of lichen epiphytes, differing in their reproductive mechanisms, dispersal structures, and rarity. Sensitivity tests showed that the molecular techniques could detect a single asexual propagule (soredium or isidium), or as few as 10 sexual spores. As proof of concept, propagule traps were deployed into a wooded landscape where the target epiphytes were present. Extractions from deployed propagule traps were sequenced, showing that the method was able to detect the presence of the target species in the atmosphere. As far as we are aware, this is the first attempt to use mechanized propagule traps in combination with DNA diagnostics to detect dispersal of lichens. The tests carried out here point the way for future dispersal studies of lichen epiphytes and other passively-dispersed microscopic organisms including fungi or bryophytes

Spatial ecology of ectomycorrhizas: analytical strategies

Spatial analysis techniques have recently become more common in ecological research. The application of these techniques to ecological problems has coincided with the development of molecular techniques for the study of ectomycorrhizal (ECM) fungal communities. Through determination of the spatial properties of ECM fungal species’ distribution (i.e. patch size and shape, degree of clustering), it may be possible to derive much more information about these communities than can be obtained from simple species abundance and frequency data. For example, the use of spatial analysis may enable detection of species interactions and temporal changes in species distribution, as well as illustrating how environmental properties may relate to ECM fungal distribution. This review discusses the application of spatial ecology concepts to, and the issues surrounding, spatially explicit sampling of ECM fungal communities in relation to current trends in ECM community research, and suggests directions for future research

Fine-scale diversity and distribution of ectomycorrhizal fungal mycelium in a Scots pine forest

Ectomycorrhizal (ECM) mycelium is a key component of the ectomycorrhizal symbiosis, yet we know little regarding the fine-scale diversity and distribution of mycelium in ECM fungal communities. We collected four 20 × 20 × 2-cm3 (800-cm3) slices of Scots pine (Pinus sylvestris) forest soil and divided each into 100 2 × 2 × 2-cm3 (8-cm3) cubes. The presence of mycelium of ECM fungi was determined using an internal transcribed spacer (ITS) database terminal restriction fragment length polymorphism (T-RFLP) approach. As expected, many more ECM fungi were detected as mycelium than as ectomycorrhizas in a cube or slice. More surprisingly, up to one-quarter of the 43 species previously detected as ectomycorrhizas over an area of 400 m2 could be detected in a single 8-cm3 cube, and up to three-quarters in a single 800-cm3 slice. ECM mycelium frequency decreased markedly with depth and there were distinct 'hotspots' of mycelium in the moss/F1 layer. Our data demonstrate a high diversity of ECM mycelium in a small (8-cm3) volume of substrate, and indicate that the spatial scale at which ECM species are distributed as mycelium may be very different from the spatial scale at which they are distributed as tips

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

In many semi-natural and natural ecosystems, mycorrhizal 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 enable the plant to access greater quantities of nutrients. Thus, there is considerable potential for plant communities to regulate the structure and function of mycorrhizal 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

Data from: Understorey plant community composition reflects invasion history decades after invasive Rhododendron has been removed

1) A growing awareness of the destructive effects of non-native invasive species has led to a massive increase in removal programmes around the world. Little is typically known about what happens to sites following the removal of the invasives, however, and the implicit assumption that the native community will return, unaided, to pre-invasion conditions is often left untested. 2) We assessed recovery of the native understorey plant community following removal of the non-native invasive Rhododendron ponticum L. from Scottish Atlantic oak woodland. We recorded understorey community composition in sites covering a gradient of increasing R. ponticum density, and across a separate series of sites covering a chronosequence of time since R. ponticum removal. We then compared both of these series to the target community found in uninvaded sites. We also analysed differences in soil chemistry between the sites to test for chemical legacy effects of invasion in the soil. 3) Native understorey cover declined as R. ponticum density increased, with bryophytes dropping to less than a third of the cover present in uninvaded sites and forbs and grasses being completely extirpated under dense stands. 4) Cleared sites showed no evidence of returning to the target community even after 30 years of recovery, and instead formed a bryophyte-dominated ‘novel community’, containing few of the typical oak woodland vascular plants. 5) Contrary to expectation, soil pH, C:N ratio, and nutrient concentrations (N, P, K, Ca and Mg) were not affected by the invasion of R. ponticum, and chemical legacy effects in the soil were not responsible for the failure of the native community to revert to pre-invasion conditions. Instead, we hypothesise that the rapid formation of a bryophyte mat, coupled with the often-substantial distances to potential seed sources, hindered vascular plant recolonisation. 6) Synthesis and applications. Clear evidence of invasion history can be detected in the understorey plant community even decades after the successful removal of invasive R. ponticum. This finding demonstrates that native communities may be unable to recover effectively of their own accord following invasive species removal and will require further management interventions in order to achieve restoration goals.30-Jun-201

Adding small species to the big picture: species distribution modelling in an age of landscape scale conservation

A recent shift in conservation policy from the site scale to the ecosystem or landscape scale requires underpinning by large-scale species distribution data. This poses a significant challenge in conserving small/less charismatic species (SLCS's) whose often cryptic nature can result in spatially restricted sampling, thus preventing landscape scale conservation projects from being realised for these ecologically important groups. Species distribution models (SDMs) can provide a powerful tool to bridge this gap. However, in the case of SLCS's (here lichen epiphytes in temperate rainforests of western Scotland are used as a model system), direct predictor variables exist at micro-scales (millimetres to centimetres), which are not extensively available in landscape-scale datasets. Here we identify a group of well-mapped larger-scale ‘compound variables’ which capture the effect of multiple direct predictors (such as bark pH and topography), and test whether they can be successfully used to predict species distributions at the landscape scale, circumventing the need for direct (micro-scale) predictor data. By testing the SDMs more widely within western Scotland, accurate predictions of species presence/absence could be made throughout the region for 5 of the 9 lichen epiphytes, making these SDMs extremely valuable as a conservation planning tool. Species distribution models utilising compound variables as predictors offer a solution to the paucity of species distributional data for SLCS's, and present a valuable resource in conservation planning for such species. The importance of testing the SDMs outside of a training region to prevent prediction error is highlighted however