Old Growth Taiga

The giant tree taiga is a cold forested biome. There are a total of four individual variants in the biome family.

Description
Much as the normal taiga can be considered a colder counterpart of the forest biome, the giant tree taiga can be considered a colder counterpart of the jungle biome. Similarly to jungle (with jungle edges) and badlands (with desert borders) biomes, giant tree taigas generate surrounded by a thin border of normal taiga to separate them from other biomes, though this border is more varied and irregular compared to the other biome borders. Spruce trees grow all over the landscape, like regular taigas, but most of them are the large 2x2 variants that grow significantly taller than regular spruce trees, and rival jungle trees in height. Much of the grass is replaced by large swaths of podzol and coarse dirt. Additionally, "boulders" made of mossy cobblestone frequently generate on the ground, and dead bushes may generate alongside the ferns and tall grass on the ground. Wolves may spawn here, as they can in all taiga variants, and rabbits may spawn as well. In Bedrock Edition, wolves and rabbits cannot spawn in these biomes. Foxes can spawn here.

As the climate here is cold, rainfall changes to snowfall at higher elevations, though this very rarely happens in even hilly variants, as the snowfall line is quite high up. There are overall more trees in giant tree taigas compared to normal taigas, leading to increased foliage density. This makes wood more abundant, though as a large portion of it grows as part of tall 2x2 spruce trees, it may be more difficult to obtain. Giant tree taigas are slightly more difficult for survival than regular taigas for this reason, though aren't so bad once acclimated and strategies are used to clear the tall trees; they may offer more unique views compared to regular taigas as well.

Variants
There are a total of four different giant tree taiga biome variants.

Giant Tree Taiga
The standard biome variant, Giant Tree Taiga features the typical podzol-covered, fairly flat terrain covered by both large 2x2 and normal-sized spruce trees, as well as mossy boulders. Wolves and rabbits are also able to spawn here. Foxes can also spawn here.

Giant Tree Taiga Hills
Like all other hills biomes, Giant Tree Taiga Hills feature elevated, hillier terrain compared to the normal giant taiga, making the landscape less suitable for shelter. Podzol, coarse dirt, and boulders may all still generate on the hills, and wolves and rabbits may still spawn. Foxes can also spawn here.

Giant Spruce Taiga
The rare Giant Spruce Taiga variant is almost indistinguishable from the regular giant taiga at first glance, though if one looks at the tops of the trees, they will notice that they have much more leaves on their tops. The giant trees in the regular giant taiga usually only have small amounts of leaves covering their tops, while the giant trees in mega spruce taigas usually have leaves surrounding much more of the tree. The much larger amounts of leaves increases the chances of saplings dropping when these trees are cut down, leading to easier sustainability. The terrain is otherwise essentially the same as the normal giant taiga, with podzol, coarse dirt, boulders; rabbits and wolves spawn in this biome. Foxes can also spawn here.

Giant Spruce Taiga Hills
Giant Spruce Taiga Hills is a variant intended to be a more mountainous version of the giant spruce taiga. However, due to a likely error in the way terrain height is calculated, there is absolutely no difference in terrain between Giant Spruce Taiga and Giant Spruce Taiga Hills. Specifically, the game uses internal values known as  and   when generating hills biomes, but these values are the same for both giant spruce taiga and giant spruce hills, resulting in no actual difference between the two(except water color). This is the only hills biome in the game with this issue.