The mycorrhizas of Europe’s pine forests in the context of nitrogen pollution
Author(s)
Cox, Filipa
Type
Thesis
Abstract
Most trees in temperate and boreal ecosystems form obligate associations with
ectomycorrhizal (ECM) fungi, but environmental change may alter ECM communities,
potentially having major impacts on forest ecosystem functioning. Understanding the
potential consequences of environmental change requires knowledge about current ECM
fungal distributions, both to provide a baseline against which to measure changes in
communities, and to establish the effects of current broad-scale environmental gradients on
mycorrhizal biogeography. This study aims to assess the feasibility of a continental-scale
survey of ECM fungal communities across a network of long-term forest monitoring plots,
and provide insights into the community ecology of these important organisms. Using a
spatially hierarchical sampling strategy and molecular identification of the fungi forming
ECM root tips, the ECM fungal communities within 12 plots in the UK and Germany were
characterised. In combination with measurements of a range of environmental variables at
the 12 plots, the data indicate that nitrogen availability is a potentially important
determinant of ECM fungal composition and richness across large spatial scales, but that
other environmental variables may also act at large scales to influence ECM fungal
communities. Evidence is also found to support a role of interspecific competition
structuring ECM fungal communities within, but not across, plots, and a complex interplay
between environmental gradients, co-occurrence patterns and phylogenetic relatedness is
revealed. Within plots, microsatellite analysis indicates that pine roots from adjacent trees
overlap, and do not have exclusive below-ground territories. Re-sampling plots, and
reciprocal transplantation of pine seedlings between plots, indicates that pine mycorrhizas
are stable both over time and on transplanted seedlings. This work increases our knowledge
of the belowground ecology of ECM fungi, and highlights the value of identifying
mycorrhizal abundance and distribution patterns - effects of global environmental change
may already be significantly altering communities of this functionally critical group.
ectomycorrhizal (ECM) fungi, but environmental change may alter ECM communities,
potentially having major impacts on forest ecosystem functioning. Understanding the
potential consequences of environmental change requires knowledge about current ECM
fungal distributions, both to provide a baseline against which to measure changes in
communities, and to establish the effects of current broad-scale environmental gradients on
mycorrhizal biogeography. This study aims to assess the feasibility of a continental-scale
survey of ECM fungal communities across a network of long-term forest monitoring plots,
and provide insights into the community ecology of these important organisms. Using a
spatially hierarchical sampling strategy and molecular identification of the fungi forming
ECM root tips, the ECM fungal communities within 12 plots in the UK and Germany were
characterised. In combination with measurements of a range of environmental variables at
the 12 plots, the data indicate that nitrogen availability is a potentially important
determinant of ECM fungal composition and richness across large spatial scales, but that
other environmental variables may also act at large scales to influence ECM fungal
communities. Evidence is also found to support a role of interspecific competition
structuring ECM fungal communities within, but not across, plots, and a complex interplay
between environmental gradients, co-occurrence patterns and phylogenetic relatedness is
revealed. Within plots, microsatellite analysis indicates that pine roots from adjacent trees
overlap, and do not have exclusive below-ground territories. Re-sampling plots, and
reciprocal transplantation of pine seedlings between plots, indicates that pine mycorrhizas
are stable both over time and on transplanted seedlings. This work increases our knowledge
of the belowground ecology of ECM fungi, and highlights the value of identifying
mycorrhizal abundance and distribution patterns - effects of global environmental change
may already be significantly altering communities of this functionally critical group.
Date Issued
2010
Date Awarded
2011-02
Advisor
Bidartondo, Martin
Barsoum, Nadia
Sponsor
Natural Environment Research Council, Forestry Commission, Forest Research
Creator
Cox, Filipa
Grant Number
NER/S/A/2006/14012
Publisher Department
Life Sciences
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)