Answer: temperature
The tundra biome is the coldest biome on planet earth. The tundra biome is found in northern Canada, Alaska, and the Arctic region. It exhibit frost molded land forms, extremely low temperatures, receives very low precipitation, and poor soil nutrition content. The limiting factor is the one which limits the abundance and distribution of the living species in an area. This includes weather condition, food availability, predation, diseases and other potent factors.
The temperature is a potent limiting factor in the tundra biome. The low temperature is because of the prolonged winter season. This leads to the freezing of the soil, dry climate and death of the animals which are not able to survive in harsh winter conditions.