When documenting an oak savanna restoration most people list only the plants and animals they have observed.  But in any restoration, what is happening in the rhizome layer plays a key role in determining the quality of a site. The interactions between fungi, plant roots, animals, and soil microbes substantially influence ecosystem process. Documenting the ectomycorrhizal fungi provides insight into these processes.  Although the vegetative structure of fungi is underground one can survey ectomycorrhizal fungi by identifying the mushrooms that fruit above ground.  Only some of the species inhabiting a woodland fruit each year, but several years of observation will yield a fairly accurate picture of a site’s mushroom diversity.

Oak trees are mycorrhizal. Most of the nutrients that oaks require to flourish are supplied by ectomycorrhizal fungi which sheath the tree roots. Branching threadlike hyphae, the vegetative portion of fungi extend outwards from the plant roots absorbing water and nutrients, particularly nitrogen and phosphorus which pass through the fungus-plant interface.  A diverse population of ectomycorrhizal fungi is essential to a healthy oak savanna.

“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 specialized at protecting against pathogens, others in enzyme production.     “  (Lena Johnson, Community Structure of Ectomycorrhizal Fungi in Swedish Boreal Forests)

Depending on the weather, fruiting of ectomycorrhizal fungi at Timberhill begins in late May or early June.  The season usually ends after hard fall frost, although it may extend into late November. The heaviest fruiting occurs in late summer, after the mid-summer dry spell. Just as do the forbs, different species fruit at different times of the season.  Mushrooms in three genera, Russula, Lactarius and Amanita are the earliest to fruit each year.  Various species in these genera will continue to fruit throughout the growing season.

Russula tenuiceps, one of many red-capped species

Russula integra, usually the first sporocarp of early summer pushes up through the moss under an east savanna shagbark hickory as early as May 26.  R. integra is one of many red capped Russula.   They can be very difficult to key to species because the macro characteristics are so similar.  After spending one season identifying all the red Russula at Timberhill , I now simply list the red ones as Russula sp. (red). However, there is a key to  Iowa Species of Russula which helps limit the choices.  It can be found in Studies in Natural History, Iowa University, vol. 11, pp. 5-31.  Otherwise the best key is in Kauffman’s Agaricaceae of Michigan published in 1918. (A 1971 Dover reprint is available through used book stores) Of the twenty or more Russula  found at Timberhill   yellow R. ochroleucoides,  crusty green R. virescens,  viscid brown R. foetens, and black R. nigricans are the most frequent.

The milky caps, Lactarius, fungi that exude a milky juice when cut begin fruiting soon after the Russula appear.  At Timberhill the earliest is Lactarius subplinthogalus, a pale capped species with a scallopped border.  The juice of this species turns pink when it dries.  Other milky caps  collected at Timberhill include L. argillaceifolius, L. fulginosus, L. gerardii, L. hygrophoroides, L. piperatus, L. volemus, L. uvidus, and L. psammicola.  The beautiful blue L. indigo also fruits here occasionally.

Lactarius subplinthogalus (note pink dried latex on sectioned specimen)

Yellow patches, Amanita flavoconia, and the Blusher, Amanita rubescens, are two early summer Amanita.  This genus includes deadly poisonous species, A. bisporigera, A. phalloides, and A. virosa.  Other species common at Timberhill are A. brunnescens, A.citrina,  A. flavorubescens, A. pantherina, and A. vaginata.

Amanita rubescens, the Blusher, stains reddish-brown where bruised or cut

Fungi that fruit in a particular open woodland vary greatly according to the species of trees. Most of the mycorrhizal fungi at Timberhill are associated with white oak, Quercus alba.   Thinning of the understory has eliminated some mycorrhizal associates, however oak savanna management has increased the abundance of highly conservative mushroom species.    Learning the fungi gives one another pair of eyes into observing ecosystem processes.  You can begin  by attending mushroom club forays. A list is available at the North American Mycological Association website.

Mushrooms and other Fungi of the Midcontinental United States by Huffman, Tiffany, Knaphus and Healy is an excellent reference for identifying Midwest fungi.

A four week course (June 20-July 15) in field mycology will be offered this summer at Iowa Lakeside Lab .  This is an excellent opportunity to learn to identify fungi using field characteristics and microscopic techniques.

Next post (1/17/2011) will continue the discussion of Timberhill ectomycorrhizal oak savanna fungi.

When we began thinning the overstocked Timberhill woodlands in 1993, the woodland management plan presented by our forester included an extension service publication of instructions detailing how to cut and stack the down wood for fuel.   It was strongly suggested after thinning our overstocked savanna proper woodland  management required reducing the ground litter. Therefore, Bill and a friend spent many days cutting and splitting wood.  They even built a crib to keep the stack above the ground.  After they had stacked enough wood to feed our fireplace for several years we decided to leave the rest on the ground.  It’s a good thing because removing all the dead wood from our restoration would have removed a valuable source of nutrients.

Crimson cups, Sarcoscypha dudleyi

The saprophytic (decomposer) fungi on down wood are so ubiquitous that they are easy to ignore.   Other than the showy species such as Crimson cups (Sarcoscypha dudleyi) and the choice edibles like Suphur shelf (Laetiporus sulphureus) I’ve never paid much attention to this group of mushrooms.  Concentric circles of Turkey tail (Trametes versicolor), the shelflike  Artist’s conks (Ganoderma applanatum) and  the scaly Dryad’s saddle (Polyporous squamosus) fruiting from dead elm during morel season are among the most common woodland fungi.  With so many more interesting species I’ve never taken an interest in this group.  It wasn’t until  recently that  I realized that decomposing plant debris may be the most important function in a woodland ecosystem.

The decaying process is much more complex in that it  appears.   It also  releases the nutrients and minerals in the dead plant material.  This is accomplished by the many species of saprophytic fungi which  are capable of  breaking down complex organic compounds into simpler compounds that plants can use. Each saprophytic fungus degrades wood by secreting different acids and enzymes.  Some of the nutrients and minerals are then released into the soil water where they become available as plant nutrients.  Without recycling by the decomposing fungi these nutrients and minerals would be locked out of the system.

Several different species may be present on the same log.     In the above photo you can see three species decomposing the same log:  Turkey tail (Trametes versicolor), is at the top left.  Below it are Reishi (Ganoderma lucidum) then a resupinate  species with spines.

There are three types of saprophytic fungi all of which can coexist in the same location.  It is believed  that the fast growing primary decomposers such as Hen of the woods (Grifola frondosa) mushrooms begin the decomposition  process by breaking down cellulose sugar.  These  are followed by the secondary decomposers that work with bacteria,  other fungi and yeasts to break down cellulose and lignin.  The tertiary decomposers such as Meadow mushrooms (Agaricus campestris) work in habitats already broken down by the former.

I am often asked what Bill and I do with down wood at Timberhill.  The answer is always the same.   Leave it and let the decomposer fungi do their work enriching  the soil to nourish the plants.

For more detail I suggest Paul Stamet’s excellent book, Mycelium Running. (Please note:  next post will be January 3, 2011)

A fascination with mushrooms is probably a holdover from my early years in post World War II Germany.  There was little food and I sometimes accompanied my mother on her frequent forays into the alpine foothills for wild food.  She gathered wild greens and berries to supplement our meager rations.  Choice edible mushrooms  such as Steinpilz (King boletes) or Pfifferling (Chanterelles) were a  special treat.  Moving to Decatur County rekindled this interest.  As restoration of our open oak woodlands proceeded I observed an increasing diversity of fungi, including the Steinpilz and Pfifferling of my early childhood memories.

King Boletes (COC=5) Ready for Cooking

In order to learn to identify the many Timberhill fungi I enrolled in Dr. Lois Tiffany’s Field Mycology class at Iowa Lakeside Lab.   There I learned to identify the major  genera of macrofungi and how to key them to species.  As my taxonomic skills increased I was amazed by the number of different species fruiting at Timberhill. Even in late fall, after a hard frost I was able to collect ten different species of waxy caps.

Wherever I found new species of fungi I observed increased diversity of conservative forbs. The more I learned the more questions I had.   Is there a  connection between mushrooms species richness and diversity of other savanna organisms? Is mushroom species abundance an indicator of  ecosystem quality?  How has extirpating tree species such as Ironwood (Ostrea virginiana) and reducing the leaf litter with annual prescribed fire affected the mycoflora?

When Dr. Gerould Wilhelm studied the impact of ten years of prescribed fire at Timberhill  I decided to monitor the ectomycorrhizal (those with a symbiotic relationship to plants)  fungi in each of the study plots.   Dr. Wilhelm set up eight plots for the study.  Two plots on adjacent land had had no management since being clearcut in 1925.  Two plots had been thinned but not burned and four had been thinned and burned annually. In 2006 I visited each plot weekly from late May through the late fall mushroom season. I documented all the ectomycorrhizal hypogeous fungi fruiting in each plot. Representative specimens of all taxa collected were identified then dried and labeled for herbarium storage.  (Since this survey only collected data for one year it does not include all the species growing in each plot.  Mushroom fruiting is ephemeral, dependent on many factors, and many species don’t fruit each year.)

Previously I’d spent a day with Dr. Tiffany and Rosanne Healy at Ada Hayden Herbarium.  Based on herbarium records we assigned COC’s to each ectomycorrhizal species on the Timberhill mushroom list. COC stands for coefficient of conservatism, a number that measures a species  fidelity to habitat.  The higher the number, the more conservative the plant.  We assigned a number between  4 – 6 if we were unsure about the quality of an area but certain that it was some kind of remnant, 7 – 8 for a fungi usually found in a pretty nice woodland, and 9 or 10 to fungi only found in a totally awesome woodland. Because of their relationship to the habitat none of the ectomycorrhizal fungi scored a COC lower than five.   For example, chanterelles (Cantharellus cibarius), COC = 5, requires four organisms to fruit:  the host tree, pseudomonas bacteria, red soil yeast and the fungus itself.

The blue milky cap, Lactarius indigo(COC=8), usually found only in mixed pine and hardwood forests is not uncommon at Timberhill which has only deciduous trees

Using the COC’s  we had assigned each species I was able to compute the floristic quality of the fungi in each plot and compare it to the FQI of the forb population.  I wasn’t sure that the numbers we’d assigned each species were accurate but was pleasantly surprised to find that the most conservative fungi were found only in plots with the highest floristic quality.  One of the unmanaged plots had the highest number of species indicating that  thinning the understory  and reducing the leaf litter affects the mushroom species composition in a woodland.  The results of the survey confirmed that there is a relationship between the fungi and  floristic quality of the plants: the more diverse the fungal community, the higher the natural quality of the woodland.  Discovering that, however, only leads to  more questions.