If you have ever watched Tintin:

Or played Minecraft:

Then you may have dreamed, as I have, of an ecosystem dominated by Fungal life.

As part of a Hard Sci-Fi RPG I'm running, I'd like one of the Continents of Quilon-3b to be dominated by Toadstool Trees and Fungal Flower Fields and Mushroom Marshes but I am not an ecologist, mycologist or anything else relevant to the idea.

What would the ground be like, what would you expect from the soil?


I am not concerned with how this environment formed. Lack of evolutionary feasability is fine. The fauna will probably not be fungal in nature. I am imagining three main biomes for the continent, Forest-like, Marsh-like, and Meadow-like(But really creepy) but these are merely ideas and it is very much up-in the air at the moment. So if you throw into your question some greater environmental implications they would be greatly appreciated. Bonus points for any sources of energy or "Producers" thrown into the Ecosystem.

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    $\begingroup$ Could you please ask one question per question? $\endgroup$
    – Mołot
    Dec 10, 2017 at 18:57
  • $\begingroup$ Please limit yourself to one question per post. And are these big pictures necessary? Many people prefer smaller pictures that leave most of the screen for relevant information for the question to be answered. Or you could also just link to the pictures. $\endgroup$
    – Secespitus
    Dec 10, 2017 at 20:57
  • $\begingroup$ I am seeing this in the reopen review queue. The problems seem to remain: there are too many questions here. Please pick one at a time to ask. Also, the large pictures are annoying. $\endgroup$
    – kingledion
    Dec 11, 2017 at 2:28
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    $\begingroup$ I dunno about Tintin or Minecraft but my first thought upon seeing "mushroom island" was Mushroom Hill Zone from Sonic & Knuckles. $\endgroup$
    – F1Krazy
    Dec 11, 2017 at 11:04
  • $\begingroup$ I have only removed one of the three questions as the other two already have answers so I have moved one of the Questions to "Notes" $\endgroup$
    – Disgusting
    Dec 11, 2017 at 14:48

4 Answers 4


The challenge with fungal-dominated environments is the absence of energy input. Fungi are decomposers, which means that they simply break down the hard work of other organisms, both flora and fauna. By their very nature, fungal ecosystems are ephemeral- that's why many mushrooms produce spores to survive and spread between the periods of food drought.

Additionally, the main part of any fungi is not the part above ground. It's a common misconception, but the largest portion of any fungus remains underground in the matrix of mycelium and hyphae. The part that breaks the surface is the sporocarp (aka a fruiting body), and has one goal- to spread spores as far as possible.

But neither of those points should be a true challenge to a worldbuilder! Let's talk about each of your biomes with those things in mind.


Check out the answer here. There are some challenges to fungal forests, but because the mycelium is always bigger than the fruiting body, the ground beneath a fungal forest is going to be almost entirely mycelium. This would give it a tough, solid texture due to the interwoven and tightly packed strands of hyphae. The ground structure would be very dense to support the large fruiting bodies without letting them fall over.

It'd be unlikely to find a producer in this environment. Thick, tightly packed ground that actively fights intrusion is unlikely to support much in the way of terrestrial plant life as we know it. As noted in the linked question, you'd probably have to get the energy from somewhere else in the world.

Fungal marshes

Fungi, while found pretty much everywhere, aren't overly fond of sitting water. Check out the link here for a small background in aquatic fungi. Essentially, fungi like to be near the edges of pools of water because there's no food in the middle. As far as soil type goes in a marsh-like environment, expect soggy, squishy masses. Fungi will gather around the edges of the pools and expand from there in both directions, breaking down material as they go. This would lead to a spongy, collapsible, quite unstable soil matrix that's probably still saturated with water and thus very squishy.

The perk of marshes is that they're already in a state of flux, which means we don't need a producer as desperately as forests would. Water is great for transporting nutrients and sugars, and if there's a slow flow of water through your marsh, whether from rainfall or tides or a slanted water table, the fungi will be quite happy.

Fungal plains

This is where you'd probably find your lichens. Lichens are fascinating, beautiful symbioses of fungi and algae (often cyanobacteria), but they aren't invincible. They require sunlight for photosynthesis, and something to break down for nutrients, like soil. Here on the plains, we've got plenty of each. Lichens would cover the surface of the soil in a thin layer, supported by the sunlight from above and the nutrients from below. Any of the lichen forms would be possible, so there could be areas of very flat, crustose forms across one area while foliose or fruticose forms would be found in wind-blown fields elsewhere.

I'd expect most of the soil here to feel similar to our current plains soil- loamy and soft, perhaps with a harder crust of fructose or foliose lichen that would be easily broken through underfoot. In areas of harder, rocky soil, the crustose forms would dominate, feeling more like the real-world rocky mountainsides where such crustose forms grow well normally.

Real-world examples

As outlined earlier, we don't have completely fungal-dominated environments because they need a huge influx of nutrients to avoid disappearing rapidly when the food is gone. We're currently cultivating a kind of mushroom-dominated environment in the Eastern US, but I'm guessing that's not what you're hoping for. In previous eras, we had mushroom-dominated ecosystems, but don't know a lot about them. And finally, even if it isn't the dominant species in the ecosystem, the largest organism on Earth that we know of is a single, spreading fungus.

  • $\begingroup$ You say marshes are "Already in a state of flux" what do you mean by this? $\endgroup$
    – Disgusting
    Dec 12, 2017 at 19:41
  • $\begingroup$ Water and air both move through marshes at a much higher rate than grasslands or forests- thus many of the nutrients and energy are already moving and don't require an immediate source of sugars $\endgroup$
    – Dubukay
    Dec 12, 2017 at 19:56
  • $\begingroup$ So it'd be sustainable if the next biome over was producing nutrients? $\endgroup$
    – Disgusting
    Dec 12, 2017 at 20:01
  • $\begingroup$ At least, within the realms of the "Physics+" level of sci-fi hardness. $\endgroup$
    – Disgusting
    Dec 12, 2017 at 20:02
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    $\begingroup$ I'll use dead bodies. WORLDBUILDING! $\endgroup$
    – Disgusting
    Dec 12, 2017 at 20:25

The first problem is that mushrooms, toadstools etc are the fruiting bodies of the fungi. They're highly seasonal and rarely last more than a few days.

Your adventuring party is going to have to be on the island at just the right time of year (ideally a sudden cold autumn triggering growth) to catch the phenomenon.

The fungi need food, they can't exist alone in an environment. Fungi come along as things are rotting, more specifically, fungi are rot. They also like it damp but mostly not totally waterlogged. To get a decent food source, match your ecology to some equally highly seasonal plants. Fast growing high density annuals that seed in the late summer just before the rains start, then die. This leaves lots of clear open ground for your mushrooms to become the dominant visible species.

The forests and plains can simply be different species that grow their mushrooms to different sizes. Perhaps the plains fungi don't compete to exclude each other so you get mixed small varieties, and the forest fungi prefer a specific species of plant to grow on and also exclude other species of fungi.

The ground is going to be relatively soft matted vegetation but firm underneath. It would be very fibrous and hard to dig through without a very sharp spade, but wouldn't be rocky as it consists of years and years of old compost.

The marsh fungi grow on the floating remains of the spring and summer marsh plants, but as you try to walk on the apparently dry ground it sinks under you and squirts water into your boot before refusing to let it go.


Fungal life thrives on "rotting" organic substrate, which they degrade further down into simpler elements, like fallen trees, etc.

Therefore to have a bonanza of fungi you need to have some superior life which can provide the substrate for them to grow. This is likely to happen if you have a fair amount of vegetable life, so that the rotting biomass can sustain the fungi.

The soil would be most likely soft and spongy, thanks to the layering of rotting vegetable and fungi (like in temperate forests).


This looks similar to your world and may offer solutions to different scenarios you may consider

Edit: Look for macrolichens in this wiki. It grows by photosynthesis so I guess it has an evolutionary reason to grow larger given the right conditions: maybe competing species in open tundra-like biome. It may grow on many types of soil or even as epiphyte.

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    $\begingroup$ This is a link only answer and will likely be closes as low quality. Links should be used to supplement your answer not as your answer. $\endgroup$
    – sphennings
    Dec 10, 2017 at 18:09
  • $\begingroup$ This would, however, be an ideal comment for the main question ;) $\endgroup$
    – Disgusting
    Dec 10, 2017 at 18:15

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