Generation Time

Another problem relates to estimating the generation time for a fungus, which has to be known in criteria A-C. In the IUCN context a generation time equals the average time from a fungus reaching maturity and producing spores, to the next generation deriving from those spores reaching maturity and starting to produce spores. How old are the fungi we see? It seems very obvious that certain fungi, growing on ephemeral resources, e.g. dung or herbaceous stems, do not reach a great age, but their spores may have been dormant for a long time before germinating, and many of such species probably have a generation time of 1 year. On the other hand, mycelia of species associated with very stable habitats, e.g. mycorrhizal species growing with old trees, saprotrophic cord and rhizomorphic formers (Chapter 1) and probably also some of the saprotrophic grassland fungi (Chapter 14), may persist for tens or even hundreds of years. For species associated with stable habitats it seems reasonable to use 10 years as a proxy of average generation time, but in some cases a considerably longer time may be appropriate.

With most of the IUCN criteria the percentage decrease in population is to be evaluated over a period of three generations; however, this interval must be within the range of 10-100 years. For the Swedish red-list (Gardenfors, 2005) it has been decided that three generations equals 50 years for mycorrhizal and litter-inhabiting fungi, 20 years for wood-inhabiting fungi, and 10 years for other species.

0 0

Post a comment