Plates and subplates
I see that L. Dutch has already given a pretty great answer to this question. I'd like to offer an alternative explanation that is not supported by real life. In real life there are plenty of active fault lines (see: Pacific Ring of Fire) located where two plates collide. In your world, I suggest the same, but with each plate having many ...
Earth has seven major plates.
You are scaling up that number by a factor 100. That would mean that, on average, the surface for each plate would scale down by the same factor, reaching the surface extension of what we call minor plates on Earth (something like the Cocos plate or the Caribbean plate).
As a consequence, the surface of each continent would ...
Taiga can, and almost always do, border tundra. Between 60 and 75 degrees north/south, taiga gives way to tundra, especially if there's a cold surface current flowing by the coast.
Look at Canada, for example, where the turquoise subarctic continental climate, aka taiga, borders grey tundra.
Cold steppes bordering taiga is, as far as I know, without ...
Copy from the real world.
A new map of standardized, mesoscale (tens to thousands of hectares)
terrestrial ecosystems for the conterminous United States was
developed by using a biophysical stratification approach. The
ecosystems delineated in this top-down, deduc- tive modeling effort
are described in ...
There are several ways to achieve this, but it depends on how large, what barriers you have between your biomes and what arrangement they are
If your Biomes are encapsulated environments (for instance, in domes):
Connect using an airlock is the most simplest way. It keeps the environments separate, allows minimal cross-contamination of species and seeds, ...
Taiga cannot border steppe (at least wide forest have to be in between, or, like in Siberia - some low forested mountain range), but tundra can (It is actualy a "cold steppe" - it would be smooth translation from cold steppe to temperate one).