Introduction - Recent research - Which trees form which mycorrhizal relationships Ectomycorrhizal Fungi are, economically, one of the most important groups of fungi. These are the fungi that form a symbiotic relationship with a plant forming a sheath around the root tip of the plant. The fungus then forms a Hartig Net which means that there is an inward growth of hyphae (fungal cell growth form) which penetrates the plant root structure. There are actually seven types of mycorrhiza and 90% of plants form mycorrhiza with fungi, but ectomycorrhizal refers to this sheath forming type. The fungus then gains carbon  and other essential organic substances from the tree and in return helps the trees take up water, mineral salts and metabolites. It can also fight off parasites, predators such as nematodes and soil pathogens. Indeed, most forest trees are highly dependant on their fungal partners and in areas of poor soil, could possibly not even exist without them. Thus in forest management, if we do not manage for the mycorrhizal fungi, we could be damaging the trees. Ectomycorrhizal relationships are common in our forests. Most trees will only form one type of mycorrhizal relationship with fungal partners. For instance, Oak, Beech and Birch all form ectomycorrhizal relationships with a number of fungi. This means that these trees are particularly good for finding fungi under. However, Ash and Sycamore for instance form Vasicular-Arbuscular mycorrhizal relationships. This type of mycorrhiza does not form fruiting bodies - if ectomycorrhizal fungi appear to be fruiting under these trees, they will be attached to the root tips of another tree a bit further away!! Mycorrhizal Fungi are a popular topic of research. Modern DNA techniques are beginning to give us an insight of what is actually going on under the ground and the first thing this research is saying is that what appears to be happening from looking at fruiting bodies above ground is not typical of the dynamics under ground!! Here are some of the research findings recently uncovered by Lena Jonsson of the the Swedish University of Agricultural Sciences in Uppsala in her PhD (Community Structure of Ectomycorrhizal Fungi in Swedish Boreal Forests, Doctoral Thesis, Swedish University of Agricultural Sciences, Uppsala, 1998). Between 60,000 and 1.2 million ectomycorrhizas were found in one square metre of forest and 95% of the root tips examined had formed an ectomycorrhizal partnership. In an examination of a 100 year old Norway Spruce forest, the above ground fruiting densities did not bear much resemblance with the mycorrhizal biomass. The 12 species that accounted for 74% of the fruiting bodies only accounted for 30% of the mycorrhizae. Species that did not produce conspicuous fruiting bodies accounted for at least 50% of the mycorrhizas and ascomycetes accounted for 20% of the mycorrhizal abundance.  Individual mycorrhizae are not perennial structures and it has been shown that 60% of the individual mycorrhizae last for longer than 6 months and 25% last more than 16 months.  When seedlings regenerate in a forest, they form their ectomycorrhizas with whatever fungi there are in that area. The ectomycorrhizas that form do not depend on the age of the tree. As ectomycorrhizas mainly form in the upper layers of soil, if the soil is disturbed by digging trenches, this drastically reduces the ectomycorrhizas available to the seedling and hence its chances of survival. This is an important thought in terms of forest management. There has long been the concept of mycorrhizal succession as different species differ in their ability to establish themselves from spores and in mycorrhizal colonisation. However, for the reasons stated in the last point, this succession may not always occur as "late-stage" species will colonise saplings where the saplings are growing in a healthy mixed aged forest.   In old forests, the ectomycorrhizal community is often made up of large fungal individuals. In the genus Suillus, individuals can often extend over 100m2. The Scandanavian sites suggest that most forests are dominated by a few species that dominate under ground with most other species having low densities. It has long been known that increased nitrogen due to atmospheric pollution has meant that the ectomycorrhizal fruiting bodies decrease in numbers. This has been a pressing concern for conservation for some time, but it now appears that increased nitrogen does not actually harm the mycelia under the ground, just the ability to produce fruiting bodies. This might be a long term problem for the mycorrhiza rather than a short term problem however. It is thought that a high ectomycorrhizal diversity is important in the healthy functioning of a woodland. Different fungi appear to have different roles. Some may be better at helping the tree take up particular nutrients, others may be specialised at protecting against pathogens, others in enzyme production. It has long been thought that many years of intensive survey are needed to produce an ectomycorrhizal species list if identifying species from fruiting bodies. Studies in Scotland showed that after 20 years, the number of new species found was still not tailing off in a Caledonian Pine forest site. An interesting thought raised by Jonsson is that this assumes that the below ground mycorrhizal community is stable. But mycorrhizae are more or less annual and that their formation depends on the availability of carbohydrates from the trees. This carbohydrate production is variable depending on the levels of photosynthesis and tree growth, thus the ectomycorrhizal community under ground will probably also change meaning that there could always be room for new species. So, the situation is dynamic and there could never be a "complete" species list!   Which trees, shrubs and flowers form ectomycorrhizal partnerships? The information here comes from "A Checklist of Mycorrhiza in the British Flora" by J.H.Harley & E.L.Harley. New Phytologist (1987) (Suppl.) 105, 1-102. This paper lists references that refer to the mycorrhizal relationship that a particular plant forms. Different types may be quoted in different papers and generally no attempt is made to review each reference. For instance, the Male Fern, Dryopteris felix-mas, is listed 14 times as forming vasicular-arbuscular mycorrhiza and 3 times as ectomycorrhizal. So beware of this and be careful about associating an ectomycorrhizal fungus with Ash, Elm, Yew or Sycamore!  Ecto stands for ectomycorrhizal, VA for vasicular-arbuscular.  Trees and Shrubs   Firs - all species Abies spp. Ecto Field Maple Acer campestre 4 VA, 2 Ecto Norway Maple Acer platanoides 5 VA, 1 Ecto Sycamore Acer pseudoplatanus 21 VA, 4 Ecto Horse Chestnut Aesculus hippocastaneum VA Alder Alnus glutinosa 7 Ecto, 3 VA, 1 ectendo Grey Alder Alnus incana 4 Ecto, 1 VA Dwarf Birch Betula nana Ecto Silver Birch Betula pendula Ecto Downy Birch Betula pubescens Ecto Box Buxus sempervirens VA Hornbeam Carpinus betulus Ecto Sweet Chestnut Castanea sativa Ecto Hazel Corylus avellana Ecto Midland Hawthorn Crataegus laevigata 2 VA, 2 Ecto Hawthorn Crataegus monogyna 3 Ecto, 1 VA Spindle Euonymus europaeus VA Beech Fagus sylvatica Ecto Alder Buckthorn Frangula alnus 7 VA, 1 Ecto Ash Fraxinus excelsior 14 VA, 2 Ecto Holly Ilex aquifolium 4 VA, 1 Ecto Walnut Juglans regia 1 VA, 1 Ecto Juniper Juniperus communis 2 Ecto, 5 VA Larch - all species Larix spp. Ecto Privet Ligustrum vulgare VA Common Mallow Malus sylvestris 5 VA, 2 Ecto Silver Spruce Picea abies Ecto Sitka Spruce Picea sitchensis  Ecto Black Pine Pinus nigra Ecto Maritime Pine Pinus pinaster Ecto Scots Pine Pinus sylvestris Ecto Poplar - all species Populus spp. Ecto and VA Wild Cherry Prunus avium 6 VA, 3 Ecto Dwarf Cherry Prunus cerasus Ecto Bird Cherry Prunus padus 2 VA, 2 Ecto Buckthorn Prunus spinosa VA Douglas Fir Pseudotsuga menziesii Ecto Wild Pear Pyrus pyraster 4 Ecto, 3 VA Oak - all species Querus spp Ecto Purging Buckthorn Rhamnus catharticus VA False Acacia Robinia pseudacacia 5 VA, 1 Ecto Willow - all species Salix spp. Ecto and VA (at different stages?) Elder Sambucus nigra VA Red-berried Elder Sambucus racemosa 7 VA, 2 Ecto Whitebeam Sorbus aria 3 VA, 3 Ecto Rowan Sorbus aucuparia 12 VA, 4 Ecto Wild Service Tree Sorbus torminalis Ecto Yew Taxus baccata VA Small-leaved Lime Tilia cordata 10 Ecto, 2 VA Large-leaved Lime Tilia platyphyllos Ecto Common Lime Tilia x vulgaris Ecto Gorse Ulex europeus VA Wych Elm Ulmus glabra VA English Elm Ulmus procera 5 VA, 1 Ecto   Flowers and Ferns   Bearberry Arctostaphylos uva-ursi Ecto, Endo, Ericoid, Arbutoid, Ectendo Male Fern Dryopteris felix-mas 14 VA, 3 Ecto White Rock Rose Helianthemum apenninum VA, Ecto, Ectendo Hoary Rock Rose Helianthemum canum VA, Ecto, Ectendo Common Rock Rose Helianthemum nummularium VA, Ecto, Ectendo Purple Colt's Foot Homogyna alpina 6 VA, 1 Ecto Wall Lettuce Mycelis muralis 5 VA, 1 Ecto Alpine Bistort Polygonum viviparum 9 Ecto, 1 VA Wild Madder Rubia peregrina Ecto Moss Campion Silene acaulis 3 VA, 1 Ecto Wood Vetch Vicia sylvatica 2 Ecto, 1 VA   Home - Our Group - Forays - BMS Foray 2000 - Mycology in NI - Atlas of NI Fungi - Interesting Finds - Edible Fungi - Database Stats - Fungal Focus - Fungal News - Fascinating Facts  - Ectomycorrhiza - Waxcaps - Herbarium - Photo Gallery - Recording Tips - Recording Form - Links - Joining Us - Dublin Group - Tree ID - Winter Tree ID - Downloads - Search the site - NIFG Discussion Forum