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Post date: Feb 15, 2011 7:35:56 PM
Background
In the Scottish alpine environment there is a suite of dominant plant species which support an ecologically significant community of symbiotic fungi; however, the diversity of these organisms is largely unexplored.
Ectomycorrhizal (ECM) fungi envelop the root tips of their host plant, exchanging soil nutrients and water for photosynthetically derived sugars, seen here on the roots of Arctostaphylos uva-ursi. Both the plants and their associated fungi are obligately dependent on the mycorrhizal symbiosis for their survival in these nutrient poor and climatically harsh environments.
This study sets out to provide a systematic biogeographic survey of alpine ECM fungi to expand greatly on the scarcity of data from these habitats, whilst providing evidence as to whether there is a suite of ECM fungi which may be considered arctic-alpine specialists in the UK.
This project also explores the extent to which nitrogen deposition and climatic factors influence ECM community composition and species biogeography.
Methods
This study focussed on 3 host plant species which have not previously been sampled for ECM fungi in the UK:
Ten sites were sampled over a range of nitrogen deposition levels, from which 10 root samples were taken from each plant species present. Fungal fruit bodies were also collected, photographed and described.
Findings so far
Over the 2009 and 2010 seasons,186 fruit body collections were made, 10 with A. alpinus, 128 with A. uva-ursi and 48 with B. nana. Cortinarius was the most common genus recorded with 103 collections, whilst other common genera included Inocybe, Laccaria, Leccinum and Russula. Within Cortinarius common subgenera included Telamonia, Dermocybe, Myxacium, Phlegmacium and Armeniaci.
The 186 collections represent at least 52 species at a conservative estimate. However, a number of cryptic species and aggregate groups have been highlighted which could not be identified to species level on morphological characteristics alone. Within Cortinarius sect Obtusi, 16 collections were made showing a wide range of morphological variation, but with no consistent characteristics to delimit to species level. Further molecular analyses using the fungal ITS region may allow delimitation of species within this group:
The fruit body of a species new to science was discovered in association with A. uva-ursi at a site in the South East Cairngorms. The species was also detected growing on the root tips of A. uva-ursi at the same site. This species falls within the Cortinarius fulvescens aggregate and has a distinct ITS sequence from other species within this group.
Several species found in association with A. uva-ursi have previously been described as specific associates of Pine species. Examples include Suillus variegatus, Rhizopogon sp.’s and Tricholoma focale. The Arctostaphylos heaths sampled are likely to have been free from Pinus sylvestris for many centuries. This supports previous findings that these fungi are not present as relics of past pine ecosystems, but are capable of inhabiting the alpine zone with Arctostaphylos as part of their primary habitat.
Whilst lowland generalist species were detected in the alpine habitat, the alpine fungal community appears to be divergent from subalpine habitats. Several alpine specialist species were found, e.g. Russula nana.
Frequent sampling for fruit bodies at one site in particular, combined with molecular identification of colonised root tips, found over 35 ectomycorrhizal taxa in association with A. uva-ursi. Whilst this is lower in species richness than many lowland ECM communities, it is nonetheless diverse, and considering levels of collecting is perhaps comparable with analogous A. uva-ursi heaths which have been studied in the Austrian Alps.
The project is being undertaken by Emily Carroll as a PhD studentship, supervised by Dr. Andy Taylor, Professor Ian Alexander, Professor Alison Hester and Dr. Dave Genney.
The project is funded by Natural Environment Research Council and Scottish Natural Heritage, and supervised by the University of Aberdeen and the Macaulay Land Use Research Institute.
If you have any questions regarding this project, the subject matter, or can suggest field sites for the 2011 field season (with plenty of Arctostaphylo uva-ursi, Arctostaphylos alpinus or Betula nana), please contact Emily Carroll via:
e-mail: e.carroll@macaulay.ac.uk
Office tel: +44 (0)1224395343
Mobile tel: +44 (0)7888718817
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