INFLUENCIA DE LOS TRATAMIENTOS SILVÍCOLAS Y EL CAMBIO CLIMÁTICO EN LA PRODUCCIÓN Y DIVERSIDAD FÚNGICA

Simon Egli. Swiss Federal Resarch Institute for Forest, Snow and Landscape Research WSL.

Intra- and inter-annual variations in mushroom yields are influenced by environmental factors. Fluctuations of fungal fruiting and the environmental drivers are, however, poorly understood in natural systems.

A few recent studies from Norway and the UK have reported shifts in the phenology of fungus fruiting bodies over the last 50 years. In the UK an extension of the autumnal fruiting season in both directions has been observed, i.e. earlier start and later finish (Gange et al. 2007). In Norway, the autumnal fruiting season has been significantly delayed (Kauserud et al. 2008), which has been coupled to an extended growing season and, hence, a delayed arrival of the autumn.

Swiss mushrooms show a clear trend for later starting and later ending of the mushroom season since 1975. The mean time of fruiting has delayed by about 10 days in this period, and has shown to be strongly related to variations in summer temperature. Seasonal mushroom yields correlate significantly positive with current precipitations.

Thinning is a common treatment in forest management. Its effects on the fungal community are complex and the findings are inconsistent. Kropp & Albee (1996) and Buée et al (2005) found that the fruit-body production of some fungi was adversely affected by thinning, while others were positively affected. Partial cutting in a western hemlock - western red-cedar forest in British Columbia led to positive, negative, and neutral responses in fungal species richness and the number of fruiting bodies (Kranabetter & Kroeger 2001). A thinning of a 12-year-old Scots pine plantation had little effect on the ectomycorrhizal fruit-body production (Shaw et al. 2003): out of 19 species tested, only three significantly responded to the thinning and increased their fruit-body production. Pilz et al. (2006) found that the number and weight of chanterelles significantly decreased after thinning. Ayer et al. (2006) observed that species richness and fruit-body abundance were much greater in medium dense Norway spruce stands than in stands with both high and low densities. Luoma et al. (2004) showed that thinning caused a decline in fruit-body production, but this effect varied greatly according to the season and to the pattern and level of thinning.

Our results show that thinning a very dense old-growth forest resulted in a clear temporal relationship between the thinning, the growth reaction of trees and the reaction of the fungal community. The ectomycorrhizal species especially reacted with a marked increase in fruit-body production and species number. Understanding past, present and projected variations in mushroom harvest and its association to a changing climate appears to be relevant not only from an environmental point of view but also from an economical perspective, since some forest mushrooms are among the world’s most expensive delicacies.