The taiga biome is a finely tuned ecosystem that cam collapse when many trees are chopped down. Here are two main causes for this biomes' collapse: logging and mining.
Logging is an industry where people go into forests and chop down trees for fire wood and other reasons. Excessive logging is a threat to taiga biomes when loggers chop down too many of the trees. A method used in logging is called clear-cutting. Using this method, loggers turn on a machine that chops down large parts of the forests.
Mining is also a threat to the taiga biome because it results into the pollution of the nearby soil and water. Because of mining, the nearby forests are pestered by acid rain from the coal smoke.