Concerns 



Effect on the Mushroom 

 Resource From Over- 

 harvesting of Mushrooms 



Morel collectors claim there are distinct morphological differences in mushrooms found 

 in burned areas, in unburned areas, early or late in the season, and between years af- 

 ter a disturbance. These observations indicate that several species may exist in the 

 Blue Mountains. These different morel species also may exhibit different reproductive 

 strategies that affect their occurrence and distribution of fruiting bodies. Effort is being 

 made to determine conditions that promote mushroom fruiting. Favorable conditions 

 are generally well known, but predicting the precise timing and location of heavy mush- 

 room production is more difficult. 



Morels may form mycorrhiza with tree roots under certain conditions. It is possible 

 that in nondisturbed conditions, much of the fruiting may be largely of a mycorrhizal 

 species, whereas after fire and heavy tree mortality, fruiting may mainly be saprophyt- 

 ic species that are triggered by the flush of carbohydrates made available when trees 

 die (see footnote 4). 



Although the biology of some morel species is well documented under laboratory con- 

 ditions, their field ecology, reproduction, taxonomy and population genetics in the wild 

 have not been well studied. The effects of fire, fire intensity, different burn season, 

 levels of tree mortality, and weather patterns are all believed to substantially influence 

 the abundance of morel fruiting. Fire and tree mortality are known to make major 

 changes in soil chemistry broadly described as nutrient flushes, pH shift, major popu- 

 lation shifts in microorganisms, and partial sterilization (see footnote 4). 



A commonly expressed concern regarding the recent surge in commercial harvesting 

 is the potential to deplete the resource by overharvesting. Some of this concern has 

 resulted from European reports of recent reductions in mushroom fruiting. Cherfa 

 (1991) reports that there has been a dramatic reduction of mushroom fruitings in re- 

 cent years. Because production records exist, it has been possible to document this 

 event. However, because edible and inedible species are both affected, overpicking 

 has been ruled out. Forest management practices have been diminished as a cause, 

 as the drop has been documented in various types of mature forests. Air pollution, 

 largely the prevalence of nitrogen, sulfur, and ozone, has been shown to suppress 

 abundance and diversity of fungi. Farming, and the application of nitrogen fertilizer, 

 also has a negative influence on fungi in adjacent communities as hydrides and oxides 

 of nitrogen are dispersed by wind and rain. In Europe, this is a concern beyond the 

 production of mushrooms for eating; many of the fungi are mycorrhizal, and their de- 

 mise has implications for the entire ecosystem. The relatively low level of industrial 

 pollutants in the air of the Blue Mountains should eliminate this as an immediate con- 

 cern. 



Currently, we do not know the effect of picking on morel populations and long-term 

 fruiting levels. This is a research need. A study of chanterelle mushrooms (C. formo- 

 sus) and the effect of picking on production has shown no short-term trends in produc- 

 tion of mushrooms associated with picking (Norvell and others 1995). Because the 

 mushroom is simply the fruiting reproductive structure of the fungus, its removal likely 

 has little affect on the remaining portions of the individual in the substrate (soil, wood, 

 etc.). 



There is concern over reduction in spore dispersal owing to removal of mushrooms. 

 Spore production does not occur until after the mushroom cap expands. Commercial 



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