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Fungi and the UK Biodiversity Action Plan
CARL BORGES
English Nature, Harbour House, Hythe Quay, Colchester COl 8JF
Introduction
Some 40 species of fungi have now been listed in the UK Biodiversity Action Plan (BAP); 28 of these
are priority species, of which 26 now have published Species Action Plans (SAP). Four species plans
are published in Volume 2 of the UK Steering Group Report and 22 in Tranche 2 Action Plans Volume
III (14 of these being grouped under a one SAP). Grouping species under a single SAP is a novel
approach and one which, for reasons I will expand upon later, is particularly suited to fungi. Table 1
lists all the fungi included in the UK BAP as well as other information on their present conservation
status.
Ecological role and need for conservation
Fungi fulfil diverse and invaluable ecological functions, some of which are outlined below:
The best known role of fungi is probably as decomposer; recycling dead organic material which can
then be used again by living organisms. Their ability to decompose wood is particularly important;
woodland covers nearly one sixth of the world's land area and 90% of woodland biomass is woody
(Hodgctts 1993).
Fungi play an important role in extending the life of old trees. Many forms of heart-rot fungi, previously
thought to mean the death of an old tree, are more likely to extend the tree's life. A hollow tree retains
much the same strength as a solid one but weighs much less. Other fungi have the effect of pruning the
less competitive branches as the canopy expands, thus reducing the sail area of the canopy and the
demand on the root system. A hollow tree with a smaller sail area is much less susceptible to wind
throw. In addition, tree roots often grow into their decaying cores to take advantage of the minerals and
nutrients released by the heart-rot fungus.
Many vascular plants, including trees, benefit from a mycorrhizal relationship with one or many species
of fungi (Rayner 1993). The fungi enhance the uptake of mineral nutrients and water by the plant whilst
the fungus benefits from a supply of organic compounds from the plant. The fungal hyphae not only
form an interface with the soil and extend the effective forage area of the root system, but can also
interconnect separate plants. These connections may even allow adult plants to nurse their seedlings.
Fungal pathogens regulate the size of the host population. This may tip the balance in favour of a
different plant community, as part of natural succession, or alternatively shape the species diversity of
a more stable community (Dobson & Crawley 1994).
Many species of invertebrate, some of which are rare and endangered, depend on fungi during part of
their life cycle. Many arc obligate fungivores. Some species feed on the fruiting bodies of fungi, others
feed selectively on the mycelium and microscopic fruiting bodies within the habitat they live (the
bacterial and fungal element of a substrate is usually the most nutritious). In addition, many dead wood
and detritus-feeding invertebrates depend on the variety of enzymes produced by fungi to help digest
their food. The degree to which different invertebrates are dependent on different species of fungi
Essex Naturalist (New Series) 17 (2000)