This question is inspired by a comment by PcMan
Imagine you have an Earth-like planet, except it is just a little farther away and has longer days. Instead of having a tropical equator, the planet now has a temperate equator with extremely cold latitudes. The planet has a day 16 times longer than our Earth's, so there are periods of day and night that last over two weeks. At night time, the temperature would be below freezing, far too cold for detritivorous insects.
Therefore, the insects would only thrive/breed during the long daytime, and die off during the night. The decomposing bodies would be plenty of food for night-time fungi.
In theory, fungal forests would be a plausible alternative to the insects at night, where they would wax in population at night and wane in the day. I define a fungal forest as a dense collection of fungi organisms. This would be in the form of decomposing animals and plants, such as bodies or rotting tree trunks.
Are seasonal fungal forests like this possible?