Search

Summary • Polycyclic aromatic hydrocarbons (PAHs) are an important class of persistent organic pollutants (POPs) in the environment and accumulate in forest soils. These soils are often dominated by ectomycorrhizal (EcM) roots, but little is known about how EcM fungi degrade PAHs, or the overall effect of field colonized EcM roots on the fate of PAHs. • The ability of eight EcM fungi to degrade PAHs in liquid culture spiked with 14C labelled PAHs was investigated. Microcosms were used to determine the impact of naturally colonized mycorrhizal pine seedlings on PAH mineralization and volatilization. • Only two EcM fungi (Thelephora terrestris and Laccaria laccata) degraded at least one PAH and none were able to mineralize the PAHs in pure culture. Where degradation occurred, the compounds were only mono-oxygenated. EcM pine seedlings did not alter naphthalene mineralization or volatilization but retarded fluorene mineralization by 35% compared with unplanted, ectomycorrhizosphere soil inoculated, microcosms. • The EcM fungi possessed limited PAH degrading abilities, which may explain why EcM dominated microcosms retarded fluorene mineralization. This observation is considered in relation to the ‘Gadgil-effect’, where retarded litter decomposition has been observed in the presence of EcM roots.

Environmental policy decisions should be based on robust indicators of changes in the environment. In Scotland these have been formalised as Ecosystem Health Indicators. Indicators work best where there is a direct link between what is measured and environmental change; changes in indices of species diversity or abundance provide alerts to environmental change but do not in themselves provide evidence of mechanisms. An alternative approach is to replace species occurrence data with species habitat or attribute values to create an indicator that links changes in species occurrences to environmental drivers. A series of indicators based on biological recording data, Ellenberg habitat preference values and mean climate niche was created by taking all records for bryophytes in Scotland (522187 records, 1960–2016) and analysing changes in mean attribute values through time for each 10 km × 10 km grid square. The resulting mean attribute values were analysed at the country level and showed clear quadratic (humped) trends for Ellenberg Nitrogen (N) and Reaction (R), an index of environmental acidity. There are linear decreasing trends for Ellenberg Light (L) and Precipitation, and linear increasing trends for January and July Temperature. Ellenberg Moisture (F) showed a clear trend, but it was not interpretable and appeared influenced by recording effort. Disaggregating to region was partly successful, but reduced samples sizes meant that for many regions the national trend was not significant. Ellenberg N and the two Temperature indices appear to be useful indicators as they are interpretable and performed better in the downscaling. Changes in L were also interpretable, but it performed poorly in downscaling to regional values. Ellenberg R appeared to be driven by changes in N as the two values are highly correlated across species. The downward trend in Precipitation ran counter to increases in rainfall suggesting that temperature driven evaporation is more likely to be driving changes in bryophyte distribution and whilst the indicator performed well it is difficult to explain to non-experts. Opportunistically collected data, like plant records, have great potential to be employed as indicators, especially as citizen scientists are involved and state resources can be used for data archiving and analysis. Also, conversion to attribute values removes many of the biases brought by differences in recorder effort and it directly links changes in species occurrences to environmental drivers.

We thank Scottish Natural Heritage for funding this work via a PhD studentship to JM. The National Trust for Scotland provided the field site and fenced the experiment. In particular we thank Kate Sampson and Lindsay Mackinlay at NTS staff for their assistance in establishing this experiment. RJM and RJP were funded through the 2011-2016 and 2016-2021 Strategic Research Programmes of the Scottish Government.

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.

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.\ud \ud A low-cost device (

Assisted colonisation, one form of species translocation, has been proposed as a tool for helping species to track suitable conditions in a changing climate. There are considerable practical challenges associated with it, including predicting where to place translocated individuals. This problem may be particularly big for small and immobile species, where small-scale micro-environmental conditions de-couple them from environmental conditions as projected in large-scale climate models. To investigate this problem we developed a survey-based model to predict the occurrence of our target species, the fruticose terricolous arctic-alpine lichen, Flavocetraria nivalis, within the Cairngorm Mountains. We then undertook an experimental translocation of this species. A second model, using variables that were significant in the survey-based model, was only fair at predicting the initial pattern of survival at the recipient site. However, model fit of the translocation survival model improved over time as the distribution of surviving individuals more accurately reflected the distribution of suitable environmental conditions. In addition, model predictive power increased with the addition of data on micro-climatic conditions at recipient plots. Synthesis and applications. Our results demonstrate that, for species which respond strongly to local environmental conditions, are immobile and, to some extent, decoupled from larger-scale climates, it may be difficult to build a priori accurate predictive models of habitat suitability. In these cases, a combination of modelling and expert judgement, along with the movement of substantial numbers of transplants, may be the appropriate options for maximising the success of assisted colonisation. This article is protected by copyright. All rights reserved.

A growing awareness of the destructive effects of non-native invasive species has led to a massive increase in removal programmes around the world. However, little is generally known about what happens to sites following the removal of the invasives and the implicit assumption that the native community will return, unaided, to pre-invasion conditions is often left untested. 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. 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. 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. 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. Synthesis and applications. Clear evidence of invasion history can be detected in the understorey plant community even decades after the successful removal of the invasive Rhododendron ponticum L. 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.

The soil seed bank plays an important role in determining what plant species emerge following the removal of monodominant invasive species. A depleted seed bank may provide a substantial barrier to site restoration, however, little is known about what changes occur in the seed bank during invasion and following clearance. This study used greenhouse germination trials to quantify and compare the seed bank present in 30 Scottish Atlantic oak woodland sites under three treatments: (1) sites featuring dense stands of the non-native invasive shrub Rhododendron ponticum; (2) sites that had been previously subject to dense R. ponticum stands but which had been cleared; and (3) uninvaded control sites. Seed banks of densely invaded and cleared sites had significantly lower species richness than those of uninvaded control sites with a lower abundance of graminoid, and to a lesser extent forb seeds than the uninvaded controls. The seed bank community composition differed significantly between the three site types. Uninvaded sites featured a wide array of species, densely invaded sites were dominated by R. ponticum seeds and cleared sites were dominated by birch (Betula sp.) seeds. Cleared sites contained very few R. ponticum seeds indicating that once effective clearance had been achieved, re-invasion would be unlikely to occur from the soil seed bank. Our findings revealed that the soil seed bank present in cleared sites was very different from the seed bank of uninvaded control sites, with clear implications for site restoration.

Increased awareness of the negative impacts of invasive non-native species has led to a rapid increase in clearance programs around the world. One of the main goals of clearance is the restoration of native communities that were present pre-invasion. Little monitoring is typically carried out, however, to verify that native communities return without further management intervention in the years following invasive species removal. We investigated whether the epiphytic plant community of Atlantic oak woodlands, which principally consists of bryophyte species, returned after up to thirty years of recovery following the removal of the invasive non-native shrub Rhododendron ponticum . This community is of international conservation value and is particularly threatened by invasive Rhododendron . We revealed that the epiphytic plant community was able to recover effectively in sites that had been clear from Rhododendron for over fifteen years. This recovery included several species of particular conservation interest with highly restricted European distributions (i.e. ‘Atlantic species’ such as Plagiochila heterophylla ). Total cover and species richness both returned to similar or even higher levels to those found in uninvaded control plots by fifteen or more years following clearance, despite being highly reduced within dense Rhododendron thickets. Overall community composition also recovered to resemble uninvaded control plots in the years following Rhododendron removal. These findings present an encouraging message that at least some native communities can return naturally in the years following invasive species removal and may not require further management interventions to speed their return.

Background: Translocating plants for conservation purposes can be a useful tool to enhance existing populations, restore lost populations or create new ones, but has rarely been done for bryophytes, especially liverworts.Aims: Here, the leafy liverwort Herbertus hutchinsiae, a representative species of oceanic-montane liverwort-rich heath, was translocated to unoccupied habitat within its current range, to establish whether its restricted distribution is due to habitat or dispersal limitation.Methods: Feasibility of establishing new populations outside the current distribution range was assessed, to test the suitability of the species for assisted colonisation. Furthermore, transplants were grown at degraded sites where the species had declined to assess potential for restoration.Results: Although maximal growth rates occurred within-range, transplants grew at all sites, indicating that the species could be dispersal limited; a conclusion supported by distribution modelling.Conclusions: Assisted colonisat...

The Scottish Government has announced that they are minded to allow reintroduced populations of Eurasian beaver (Castor fiber), an ecosystem engineer, to remain in Scotland. Some species and habitats of conservation importance may be affected by the activities of an ecosystem engineer. The study had two key objectives: to identify the potential location of the beaver’s two ecosystem engineering activities and to assess risks to vulnerable habitats and species. To identify potential core beaver woodland, a rule-based species distribution model was developed which included a novel method of integrating beaver territory size requirements. This was used to further predict where beavers would be unlikely to dam. We used the models to assess the spatial overlap between ecosystem engineering activities (i.e. herbivory and damming) with habitats and species of conservation importance. One hundred and five thousand five hundred eighty-six hectares of core beaver woodland was identified, which predicted the location of beaver herbivory. Our model successfully predicted the location of beaver activities surveyed in the largest beaver population in Scotland. Extensive overlap was predicted between beaver herbivory and habitats of conservation importance, in particular aspen woodland, Atlantic hazelwood, and alluvial forests. Eighty-seven percent of watercourses in Scotland were outside the beaver damming model, and hence had a lower likelihood of being dammed. The majority of freshwater pearl mussel, lamprey and Atlantic salmon Special Areas of Conservation, were in river sections less likely to be dammed. If beavers recolonise their former range in Scotland, ecosystem engineering activities are likely to be extensive. However, any impacts on vulnerable species and habitats will be in specific areas and will need to be monitored.

The criteria set out by the International Union for Conservation of Nature to identify threatened species requires information on population trends which, for priority lichen species within Scotland, is lacking. Collecting such data is problematic as there is a lack of empirical information on the performance of different sampling designs and survey methodologies. Using Pseudocyphellaria norvegica as an example species, we tested differences in the efficiency of 3 transect patterns and a 20 minute search for surveying 100×100 m cells of potentially suitable habitat. The methods were not intended to census the total population of the cells but, rather, to provide a standardized, repeatable estimate of the population density to allow detection of trends through time. We also tested the repeatability of the methods between surveyors. The results provided no evidence to suggest that controlled survey methodologies using fixed transect patterns were any better in terms of consistency between surveyors or numbers of occupied trees found than 20 minute searches of the areas within each 100×100 m cell deemed suitable for the target species by an experienced surveyor. Given that following the fixed transect patterns took approximately twice as long as a 20 minute search, the search method would clearly be more cost-effective when there are large numbers of cells to survey. For all survey methods variability between surveyors was high, meaning that it would be extremely difficult to detect temporal changes in populations, and hence identify population trends. We also examined the extent to which recording presence/absence at the 1 ha scale might improve consistency between surveyors and found that it reduced, but did not eliminate, the surveyor variability. Recording only presence/absence would allow greater numbers of cells to be surveyed using the same level of resources, but would reduce the amount of information available per cell for use in analysis of population trends. We conclude that controlling inter-surveyor variability while collecting adequate data for population trend analysis is a major issue when planning and implementing any large-scale survey of lichen species.

The lichenized basidiomycete known as Dictyonemainterruptum is a widely distributed but rare, oceanic, western European species known from the British Isles, the Pyrenees, the Azores, and Madeira. Unfortunately, the name has never been validly published. The species was first described in the cyanobacterial genus Calothrix in 1833, which predates the starting point of heterocystous bacterial nomenclature, 1 January 1886. The epithet was never subsequently included in a validly published binomial and its combination into Dictyonema was therefore invalid as well. There was also controversy about whether the epithet applied to the cyanobacterial photobiont (as originally intended) or to the lichen fungus (as proposed later). Because of the lack of a valid description for this epithet, we have chosen to establish a new name, Dictyonema coppinsii Lücking, Barrie & Genney, for the lichenized fungus at hand, whereas the cyanobacterial photobiont is validated with the genus name Rhizonema Lücking & Barrie, adopting the epithet interruptum for it, and placed in a separate family, Rhizonemataceae Büdel & Kauff ex Lücking & Barrie.

Background: Liverwort heath is considered in Scotland to be one of the vegetation types most vulnerable to environmental change, yet detailed insights into its dynamics are lacking.Aims: To assess the nature and extent of plant compositional changes in liverwort heath over 50 years and relate this to environmental change drivers.Methods: Vegetation plots previously recorded 20 and 50 years ago were re-surveyed to assess changes in species composition, plot-level species richness and between-plot variability, using several β-diversity indices and partitioning. The environmental indicator values of the species that showed most change were used to identify the environmental drivers of change.Results: Liverwort heath in north-west Scotland has undergone compositional changes over 50 years, becoming more heterogeneous, and losing some of its distinct character. Dwarf shrubs and specialist liverworts have decreased, while graminoids have increased. Partitioning of change in β diversity indicated that mainly cha...

Hypocreopsis rhododendri is a rare fungus that grows on woody stems in hyperoceanic climax scrub on the west coasts of Britain, Ireland, and France. Knowledge of the distribution and abundance of the fungus is based entirely on sporocarp records; it does not account for any occurrence as vegetative mycelia. To address this issue, a H. rhododendri-specific polymerase chain reaction (PCR) was developed and used to assay Corylus avellana (hazel) stems for the presence of H. rhododendri mycelia. The primers ITSHrF and ITSHrR were designed within the internal transcribed spacer 2 region, and their specificity to H. rhododendri was established by their failure to amplify DNA extracted from 14 other Hypocreaceae species. The sensitivity of the assay was demonstrated by amplifying DNA extracted from 4 mg C. avellana wood spiked with 0.0013 % H. rhododendri mycelium. Samples of wood and bark were then taken from around and directly underneath 11 H. rhododendri sporocarps and assayed for the presence of H. rhododendri. PCR products were obtained from a third of the surface bark samples, but only one faint product was obtained from 70 samples taken from beneath the outer bark. The results support the view that H. rhododendri does not form mycelia within stems. We suggest that H. rhododendri is not a saprotrophic fungus, but instead appears to be a parasitic on the wood decay fungus Hymenochaete corrugata, with which it always occurs. Evidence that tissue of H. corrugata is present within the sporocarps of H. rhododendri is discussed.

We review the state of fungal conservation in Europe. Despite a large public interest in fungi, they are often insufficiently considered in the conservation initiatives of most countries and not adequately heeded in international biodiversity agreements. We attribute this to the generally low profile of fungi among conservation stakeholders and decision makers together with limited efforts of mycological scientists to put mycological knowledge into a conservation context. Recent advances in mycological knowledge, taxonomy, distribution, ecology and threats now categorically enable fungi to be included within national and European conservation agendas. 33 European countries have produced fungal Red-Lists reporting the status of macrofungi and these are official in 20 countries. These lists indicate that at least 10 % of European larger fungi are threatened, mainly due to changing land use and nitrogen deposition. Fungal biodiversity may benefit from many general conservation efforts, but many specific fungus values are also overlooked. We advocate increased interaction between scientists and conservation coordinators and practitioners, greater promotion of fungi and their conservation and ecosystem service values by mycologists, the production of a European fungal Red-List and the need to integrate fungi with animals and plants in conservation issues.

Summary 1 Spatial variation and covariation in host-plant quality, herbivore abundance and herbivore mortality were examined across the natural geographical range in Europe of holly Ilex aquifolium and the host-specific holly leaf-miner Phytomyza ilicis. 2 Although measures of host-plant quality showed substantial between-site variation, no simple spatial pattern in any of the measures (only phosphorus content and leaf mass showed correlations with latitude, longitude or altitude) was detected, and few correlations with tree or local site characteristics. 3 In contrast, measures of the abundance of the leaf-miner exhibited marked spatial patterns, resulting in a lack of simple covariance between leaf-miner abundance and host-plant quality. 4 Different apparent mortalities of the leaf-miner exhibited varied spatial patterns in their intensity, but no evidence of range-wide density dependence, again resulting in few patterns of covariance between intensity of mortality and measures of host-plant quality. 5 The population dynamics of the holly leaf-miner across its geographical range are complex. At any site, the mortality that a population experiences is the sum of largely independent yet spatially structured components, against a background of varying host-plant quality. Despite lacking any marked spatial structure, host-plant quality may have important local effects. These are difficult to detect regionally, and thus may principally contribute noise to regional patterns of levels of oviposition, abundance and mortality.

Complexes of arsenic compounds and glutathione are believed to play an essential part in the metabolism and transport of inorganic arsenic and its methylated species. Up to now, the evidence of their presence is mostly indirect. We studied the stability and chromatographic behaviour of glutathione complexes with trivalent arsenic: i.e. AsIII(GS)3, MAIII(GS)2 and DMAIII(GS) under different conditions. Standard ion chromatography using PRP X-100 and carbonate or formic acid buffer disintegrated the complexes, while all three complexes are stable and separable by reversed phase chromatography (0.1% formic acid/acetonitrile gradient). AsIII(GS)3 and MAIII(GS)2 were more stable than DMAIII(GS), which even under optimal conditions tended to degrade on the column at 25 °C. Chromatography at 6 °C can retain the integrity of the samples. These results shed more light on the interpretation of a vast number of previously published arsenic speciation studies, which have used chromatographic separation techniques with the assumption that the integrity of the arsenic species is guaranteed.

Sheep on the island of North Ronaldsay (Orkney, UK) feed mostly on seaweed, which contains high concentrations of dimethylated arsenoribosides. Wool of these sheep contains dimethylated, monomethylated and inorganic arsenic, in addition to unidentified arsenic species in unbound and complexed form. Chromatographic techniques using different separation mechanisms and detectors enabled us to identify five arsenic species in water extracts of wool. The wool contained 5.2 ± 2.3 µg arsenic per gram wool. About 80% of the arsenic in wool was extracted by boiling the wool with water. The main species is dimethylarsenic, which accounted for about 75 to 85%, monomethylated arsenic at about 5% and the rest is inorganic arsenic. Depending on the separation method and condition, the chromatographic recovery of arsenic species was between 45% for the anion exchange column, 68% for the size exclusion chromatography (SEC) and 82% for the cation exchange column. The SEC revealed the occurrence of two unknown arsenic compounds, of which one was probably a high molecular mass species. Since chromatographic recovery can be improved by either treating the extract with CuCl/HCl (CAT: 90%) or longer storage of the sample (CAT: 105%), in particular for methylated arsenic species, it can be assumed that labile arsenic–protein-like coordination species occur in the extract, which cannot be speciated with conventional chromatographic methods. It is clear from our study of sheep wool that there can be different kinds of ‘hidden’ arsenic in biological matrices, depending on the extraction, separation and detection methods used. Hidden species can be defined as species that are not recordable by the detection system, not extractable or do not elute from chromatographic columns. Copyright © 2003 John Wiley & Sons, Ltd.

Summary 1 We conducted an experiment to investigate the effect of organic matter distribution on below-ground competition between the dwarf shrub Calluna vulgaris (L.) Hull and the coarse upland grass Nardus stricta (L.). 2 The two species were grown alone, or in competition in pots where the substrate was either a sand layer overlain by a peat layer (layered), or the same volume of peat evenly mixed with sand throughout the pot (mixed). 3 Root length and allocation in the top, middle and bottom of each pot was measured, along with plant biomass. 4 Calluna allocated the greatest proportion of root length to the top of the pot, irrespective of the peat distribution. Nardus allocated a large proportion of root length to the bottom of the pot. Root allocation by Nardus to the top and middle of the pot was positively related to the distribution of peat. 5 Nardus grown alone attained greater shoot mass in the layered than in the mixed substrate, but this was not the case when Calluna was present. Calluna was the superior competitor in both layered and mixed-substrate pots, but more so in the latter. 6 This was attributed to (i) the ability of Calluna to exclude Nardus roots from the upper organic material in the layered substrate, and (ii) the greater plasticity of root allocation of Nardus, enabling it to avoid competition with Calluna.

Summary • The relationship is examined here between Nardus stricta root length colonized (RLC) by arbuscular mycorrhizal (AM) fungi (% RLC) and vegetation composition in a heathland community. • Two approaches were taken: a field survey of AM colonization of Nardus at two contrasting locations (Glen Clunie and Glen Shee, UK) in relation to vegetation composition; and an 11-month bioassay of AM inoculum potential in Calluna vulgaris and Nardus swards using uncolonized Nardus transplants. • In the field survey, % RLC of Nardus was positively related to Nardus density. This relationship was strongest in Glen Clunie, probably because overall colonization levels were lower at the more fertile Glen Shee site. In the bioassay, Nardus transplants within Calluna swards developed little or no AM colonization, whereas those within Nardus swards had a mean RLC of 23%. • This is the first report that degree of AM colonization is related to host density in the field. Isolated Nardus plants in Calluna swards might be disadvantaged compared with Nardus plants in Nardus swards because of lower of AM colonization.

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-cm(3) (800-cm(3)) slices of Scots pine (Pinus sylvestris) forest soil and divided each into 100 2 × 2 × 2-cm(3) (8-cm(3)) 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 m(2) could be detected in a single 8-cm(3) cube, and up to three-quarters in a single 800-cm(3) 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-cm(3) ) 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.

Microbial ecology has made large advances over the last decade, mostly because of improvements in molecular analysis techniques that have enabled the detection and identification of progressively larger numbers of microbial species. However, determining the ecological patterns and processes taking place in communities of microbes remains a significant challenge. Are communities randomly assembled through dispersal and priority effects, or do species interact with each other leading to positive and negative associations? For mycorrhizal fungi, evidence is accumulating that stochastic and competitive interactions between species may both have a role in shaping community structure. Could the methodological approach, which is often incidence based, impact the outcomes detected? Here, we applied an incidence-based Terminal Restriction Fragment Length Polymorphism (T-RFLP) database approach to examine species diversity and ecological interactions within a community of ectomycorrhizal (ECM) fungi. Co-occurrence analysis revealed that the ECM community colonizing root tips was strongly structured by competitive interactions, or ecological processes generating a similar spatial pattern, rather than neutral processes. Analysis of b-diversity indicated that community structure was significantly more similar (spatially autocorrelated) at distances equal to or

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.

Soil basidiomycetes play key roles in forest nutrient and carbon cycling processes, yet the diversity and structure of below ground basidiomycete communities remain poorly understood. Prescribed burning is a commonly used forest management practice and there is evidence that single fire events can have an impact on soil fungal communities but little is known about the effects of repeated prescribed burning. We have used internal transcribed spacer (ITS) terminal restriction fragment length polymorphism (T-RFLP) analysis to investigate the impacts of repeated prescribed burning every two or four years over a period of 30 years on soil basidiomycete communities in an Australian wet sclerophyll forest. Detrended correspondence analysis of ITS T-RFLP profiles separated basidiomycete communities in unburned control plots from those in burned plots, with those burned every two years being the most different from controls. Burning had no effect on basidiomycete species richness, thus these differences appear to be due to changes in community structure. Basidiomycete communities in the unburned control plots were vertically stratified in the upper 20 cm of soil, but no evidence was found for stratification in the burned plots, suggesting that repeated prescribed burning results in more uniform basidiomycete communities. Overall, the results demonstrate that repeated prescribed burning alters soil basidiomycete communities, with the effect being greater with more frequent burning.

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 x 20 cm x 2 cm slices of pine forest soil into 100 cubes of 2 cm x 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.

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.

The role of ericoid mycorrhizal colonization in competition between the dwarf shrub Calluna vulgaris and coarse grass Nardus stricta was investigated. Nardus was grown alone, or in competition with Calluna, in a layered organic/sand substrate with and without inoculation with the ericoid mycorrhizal endophyte Hymenoscyphus ericae, and with and without the addition of nitrogen. Root length and allocation between different substrate layers was assessed along with plant biomass, nutrient uptake and mycorrhizal colonization. Calluna was the superior competitor for nutrients, probably because of its ability to concentrate root growth in the upper organic layer. In the presence of Calluna both the absolute amount and proportion of Nardus root length in the organic layer were reduced, and this reduction was greatest when Calluna was mycorrhizal. The presence of ericoid mycorrhizal colonization did not reduce Nardus shoot nutrient content or concentration, suggesting that ericoid mycorrhizal suppression of Nardus growth was not due to nutrient competition: alternative mechanisms of interference are discussed.