Loving mushrooms to death?

Jim Worrall jworrall at mailbox.syr.edu
Fri Jan 3 17:57:35 EST 1997

Quite an interesting discussion has developed here on the impact
of mushroom harvesting on population dynamics of the fungus.  
Someone may have mentioned it already, but there is a good 
article on one study of this question:

Norvell, L. 1995.  Loving the chanterelle to death?  The ten-year
Oregon chanterelle project.  McIlvainea 12(1): 6-25.

Preliminary empirical data from that study indicate that
harvesting has not affected future productivity on the site,
within the 9 years of the study.  One difficulty with
any such study is the spores that come in from the surrounding
countryside.  You could detect any direct effect of harvesting
on productivity of existing mycelia, but not the effect of
large-scale harvesting on development of new mycelia from

Based on very limited data from a few published studies
of spore production (e.g., Largent and Sime 1994) and numbers
of primary and secondary mycelia of other fungi, I have been
toying with some stage-based matrix models of population
growth and looking at the effect of reducing various
parameters, including fertility of fruiting mycelia (which
simulates harvesting).

I hasten to add that the models are highly hypothetical and
simple, but they do shed light on parameters that might be
important in population dynamics.  The results will be
published in a book, "Structure and Dynamics of Fungal
Populations."  Depending on the stage distribution
(basidiospores: primary: secondary non-fruiting: fruiting mycelia)
and on the transition probabilities among those stages,
fungal species may vary tremendously in their sensitivity
to perturbations such as heavy harvesting.  Some may be
more sensitive than we expect.  

Of course, as others have said, we need more data to really
answer the question behind this discussion.  These models
may help us think about what kinds of data we need.

Jim Worrall
SUNY College of Environmental Science and Forestry

Jim Worrall
SUNY College of Environmental Science & Forestry
Syracuse NY 13210

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