Final answer:
The taiga, or boreal forest, is the largest terrestrial ecosystem, covering large areas in the northern hemisphere just south of the Arctic tundra and is characterized by coniferous forests.
Step-by-step explanation:
The largest terrestrial ecosystem is the taiga, also known as the boreal forest or evergreen forest. This biome is extensively found in the northern regions of North America, Europe, and Asia just south of the Arctic tundra. Characterized by coniferous forests, the taiga represents the largest biome in Russia and is one of the largest on Earth. Despite the dominance of cold temperatures and coniferous trees, biomes like the taiga and others such as tropical rainforests, deserts, grasslands, and tundras, each have unique levels of biodiversity and vegetation that define them. For instance, while deserts are arid and sparsely vegetated, tropical rainforests near the equator boast the highest biodiversity. Meanwhile, grasslands are dominated by grasses and the tundra by lichens and very short growing seasons due to extreme cold.