. The Canadian field-naturalist. . Figure 3. A ring of Type 111 with sporophores of//vgrop/2orwiA7/vew5, photographed in October, 1970. The ring was m in diameter. Although the lighting appears non-uniform, there was no alteration of the vegetation. each species is given in Table 1. The expansion rate varied from 7 cm per year for Clavaria cinerea to 75 cm per year for Clitocybe subconnexa. The expan- sion rate was characteristic for each species. A vari- ability of ± 15% appeared to be related to the annual rainfall but exact correlations were not made. Based on the diameter of a ring and
. The Canadian field-naturalist. . Figure 3. A ring of Type 111 with sporophores of//vgrop/2orwiA7/vew5, photographed in October, 1970. The ring was m in diameter. Although the lighting appears non-uniform, there was no alteration of the vegetation. each species is given in Table 1. The expansion rate varied from 7 cm per year for Clavaria cinerea to 75 cm per year for Clitocybe subconnexa. The expan- sion rate was characteristic for each species. A vari- ability of ± 15% appeared to be related to the annual rainfall but exact correlations were not made. Based on the diameter of a ring and the expansion rate, the approximate age of the ring can be estimated. Calcu- lated in this way, the oldest ring in this study was a ring of Type I-, which was 75 years old when it disappeared. This calculation has been applied to rings in Colorado, where rings of Agaricus tabularis were determined to be 250 years old (Shantz and Piemeisel 1917) and to rings in England where a ring of Clitocybe geotropa was determined to be nearly 700 years old (Smith 1957). In this study, few rings survived past an age of 50 years, and during the study 75 rings disappeared for various reasons. Many rings were killed by grass fires; no ring has ever been observed to revive after being burned over. Other rings disappeared when fields were ploughed. Many rings occurred in fields where forests were regenerating and they disappeared as the ground cover changed from grasses to forest litter. In contrast, some species continued to flourish under a forest cover, most notably Tricholoma irinum and Hygrophorus russula (Table 1, Type 0). Many rings were disrupted when they encountered obstacles such as rocks, roadways, or trees, and frequently there was no obvious cause for the disruption. Segments of many rings disappeared without apparent cause, leav- ing residual arcs: 15 rings disappeared completely in this way. An interesting feature of fungus rings is the uni- directional outward growth. Reverse (
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