Production and Forest Management

Wild edible mushroom harvest generates millions of dollars each year and consists largely of ectomycorrhizal fungi, such as pine mushrooms (Tricholoma magnivelare), chanterelles (Cantharellus formosus and Cantharellus subalbidus), and boletes (B. edulis) (Danell and Camacho 1997). Pine mushrooms are the most commercially important wild forest mushroom and are exported exclusively to Japan (de Geus 1995), while chanterelles, boletes, and others are primarily exported to parts of North America and Europe (de Geus 1995). Known commercial mycorrhizal mushroom (particularly tubers) sites are located across all the regions of France (de Geus 1995; Freeman 1997; Trowbridge and Macadam 1999; Ehlers and Frederickson 2000; Berch and Wiensczyk 2001; Kranabetter et al. 2002), in forests from 20 to more than 200 years old (Hosford and Ohara 1995; Norvell 1995; Redhead 1997; Pilz et al. 1998). Forest practices, such as logging, site preparation, tree selection, fire, fertilization, pesticide use, brushing and spacing, and grazing, influences mushroom presence, reproduction, and productivity. Ectomycorrhizal fungi require living roots, and therefore living trees, to survive. As a result, timber harvesting, particularly clearcutting, profoundly reduces mushroom production (Smith et al. 2002) until the mature forest becomes reestablished. In some areas, gap area size significantly affects the production of fruiting bodies in forests (Durall et al. 1999, 2006). Sporocarp diversity declines significantly in forests as soil compaction from machinery and trampling can damage the mycelium and reduce mushroom productivity (Colgan et al. 1999).

Forest management techniques that promote mushroom production have been studied in many countries. To encourage matsutake mushroom production in Japanese forests, for example, various silviculture treatments have been applied. Overstorey trees are thinned, tree species composition is altered, nonhost under-storey shrubs and herbs are cut, and organic litter is removed from the forest floor (Hosford et al. 1997). In North America, such intense management of forests for pine mushroom production does not occur. Studies in Europe show that nitrogen deposits from air pollution (Arnolds 1991) and applications of nitrogen fertilizers (Termorshuizen 1993) reduce the productivity of edible ectomycorrhizal fungi. Information on the effects of pesticide application or grazing on edible mushrooms is currently not available for any country. More research is required to determine how silviculture techniques could be used to promote the fruiting of economically important fungi in forests across the globe.

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