But controlled burns and fires that otherwise do not cause complete incineration of the symbiotic trees/plants would not result in the death of the fungi. However, with the ground cleared, the spores would travel further.

There are also fire-dependent plants that are reproduction-adapted for these conditions.

"Some cones, such as those of lodgepole pine and sequoia, are pyriscent, as well as many chaparral shrubs, meaning they require heat from fire to open cones to disperse seeds."

https://en.wikipedia.org/wiki/Controlled_burn

Yes, it's an adaptation for a particular ecosystem.

Most california sages also require the presence of ashes to germinate. It's quite common amongst flora in the California chaparral. In large part due to thousands of years of ecosystem management with controlled burns by native Californians. In a lot of ways California is a manufactured landscape (though even Amazonia has been labelled as manufactured[0] so it's not all that surprising)

[0] https://www.researchgate.net/publication/259126195_Dark_eart...

I'm not sure if that is quite accurate although it is plausible given the negative effect of hotter fires in traditionally fire controlled areas. I read into this a couple years ago and found published data on increased harvests of morels in terms of kg/hectare after large forest fires [example from looking again today 1]. I think as humans we are biased to think above the ground and think of destruction.

There could be a a difference due to an intensely hot fire in an area where fires have been historically suppressed. There is a survey of pickers on whether hotter fires are more or less productive with 29% vs 54% [2] but I don't know the methadology.

[1] 'Approximately 250 000 ha of British Columbia forest lands were burnt (Filmon 2004). In the East Kootenay region alone, a total of 43 679 ha burned that year. Based on this figure, the apparent correlation of morel production with recent wildfire exposure, and the morel production levels observed in random experimental plots (7568 morels per hectare), Keefer (2005) estimated that 76 × 107 kg ascocarps grew in the region in 2003. Assuming the average weight of morels harvested in the region matches the 20 g per ascocarp observed by Pilz et al. (2004) in the United States, this would amount to 2.27 × 107 kg of morels produced in the region during the first flush of 2004. The size and scope of subsequent flushes is unknown but based on observations of two additional flushes in the burnt forest at Lamb Creek (Winder and Keefer 2008), the actual size of the potential morel crop could be tripled from the above estimate' https://cdnsciencepub.com/doi/10.1139/B08-045

[2] https://central.bac-lac.gc.ca/.item?id=mr05125&op=pdf&app=Li...

Do those studies look long term though? Increased harvests is exactly what you'd expect from the phenomenon I described.

That's a good point. I'm not sure. Some areas I pick edible mushrooms other that morels have not recovered from logging or fires short or long term so my individual anecdotal experience is no. I couldn't find good data on chanterelles or boletus species.

I don't think morels are entirely reliant on myccorrhizal relationships. There have apparently been successful small scale farming attempts without trees, check out the Danish Morel Project.

Either way, if hosts dying was all there was to it, you'd expect all sorts of myccorrhizal mushrooms to grow after a fire, and most don't.

I've definitely seen morels go crazy after their host tree dies - whether by fire or a saw. I also agree that they can likely be partially saprobes, so maybe this adaptation is related more to the latter than the former. I was just pointing out that I think it's far from settled that "fire is good for morels" is true in general, especially for mega fires.