Land Biomes in Thrive

[aaronmkersh]

@Rathalos

Classification of “patches” into biomes (in the true ecosystem sense) is in my opinion necessary but by itself insufficient for Thrive’s purposes. In order play a mountain theme in mountain “patches”, we do need to categorise which patches are mountains. This means we need a terrain classification either baked into biomes (as is the case in microbe stage) or a new separate system entirely parallel to the real ecosystem-based biome. So that would respectively be “Biome: Desert (mountains)“ or “Biome: Desert + Terrain: Mountains”.

The same goes for hills, plateaus, presence of rivers maybe, etc.

I see what you’re saying, and I think the latter option is better, having a separate biome and terrain classification. Terrain is too complicated of a factor to bake into our biome classification scheme in my opinion. Some biomes, like wetlands, can only exist with highly specific terrain, while others like desert can exist anywhere with certain parameters, in this case little rain.

@Rathalos

That would be in place of the multi-tier biome system where you define then “end biome”, with lower tier biomes replacing them if the right type of plants are not available.

I think I was slightly misleading with my “tier system”. There is no built-in progression for biomes, and biomes are only defined by what is there in the patch, a.k.a the humidity, temperature, and species. If one generation there’s enough trees, it’s a forest. If next generation they are outcompeted by grass due to changing conditions, it’s a grassland. If the planet then freezes over, it’s a polar desert. The tiers were initially meant to represent higher biodiversity, but I jumped the gun on that when I added T4 for grassland, as a grassland will have lower biodiversity than a forest.

@Rathalos

I agree designing this to be likely is probably a nice thing to do. But this is Thrive, so likely does not mean guaranteed. It’ll likely be at least possible for something grass-like to evolve before something tree-like does. What happens to the succession tier pattern when grasses exist but trees do not?

You’re right about this, and the answer would simply be, there are grasslands but no forests. A “succession pattern” for biomes is only relevant when totally uninhabited rock is being colonized for the first time by life.

@Rathalos

You seem to assign all pre-shrub scrubland as (cold) desert. Now, shrubs are actually defined as still pretty decently sized woody plants. And as far as I can tell from a quick wiki search, those are a middle-Devonian development. But in the early Devonian (and later Silurian?), there were still a lot of small herbaceous plants. Rather than desert, I think this would be visually more similar to (alpine) tundra, rather than desert? (Please ignore the Prototaxites, they’re… weird)

@Rathalos

• Going even earlier into the Silurian and late Ordovician, we’re probably moving into seeing only moss and lichen (and algal/bacterial mats). Still tundra? Or is that Barrens? To us maybe, but to the arthropods we know were crawling around, probably not.
• Speaking of algal/bacterial mats, which make for example stromatolites, they’re also around during some of the timeframes above, and before then. Afterwards, the evolution of other flora and grazing fauna prevented them from defining the ecosystem anymore. How would you classify a biome where just this stuff is covering everything?

So these are some good weird cases to think about, and I think these can be addressed by clarifying some sub types of Barrens and Desert.

Inhospitable barrens don’t have life, even microbes, because they cannot support it.

Abiotic barrens can support life, but have none yet.

Pioneer barrens have life, but no soil yet. They are still undergoing primary succession. There notably is rainfall. If there’s a lack of rainfall/humidity, this is instead a desert.

Deserts are defined entirely by lack of rainall/humidity.

It’s worth noting, many deserts actually have quite a lot of vegetation. I’ve added Arid, Semi-arid and Coastal desert, with Semi-Arid being typically the most lush subtype. The line between desert, steppe, scrubland, etc. gets pretty blurry and in my opinion arbitrary, but for Thrive, I think environments with “plants but not grasses or shrubs” generally qualify as either Pioneer barrens or Semi-arid desert, depending on the extent of soil development.

You can see I’ve redone the tiers, which are only meant as a tool to indicate present key species, and correspond loosely to biodiversity levels. Some types of Tundra could perhaps be T1.

I’ve also deleted the table showing examples of various biomes’ succession, as it’s perhaps a little misleading. Instead, I’ve created an example scenario of how a single patch might develop over time, to highlight the range of possibilities.

As for Prototaxites… Let’s just throw it in the Pioneer Barrens bucket! But seriously, I think that’s the best solution for weird organisms like that. Same for bacterial mats, stromatolites, and any weird alien things that we can’t classify as shrubs, grass or trees. I’m sure auto-evil (I meant to type auto-evo just now, but I’m leaving it) will mock our attempts at classifying plants and biomes, but we gotta draw the lines somewhere.

As a side note, I revisited wetlands, because I had a Saltwater Wetland and Freshwater Wetland biome under Marine and Freshwater biomes respectively, and that felt wrong to me. The whole point of wetlands is they’re a transitional zone between land and sea, so I’ve created a special transitional biome category just for them. You win, wetlands.