In the ponderosa pine forests of the West, large pine trees that have survived dozens of fires prior to the last wildfire (which usually happened in the late 19th or early 20th Century), are now extremely vulnerable to fire.
(large pine trees; have survived prior; dozens of fires) (the last wildfire; happened; T:in the late 19th; T:early 20th Century; T:usually) (large pine trees that have survived dozens of fires prior to the last wildfire (which usually happened in the late 19th or early 20th Century); are; T:now; extremely vulnerable to fire; L:In the ponderosa pine forests of the West)
large pine trees the last wildfire large pine trees that have survived dozens of fires prior to the last wildfire (which usually happened in the late 19th or early 20th Century)
have survived prior happened are
dozens of fires
T:in the late 19th T:early 20th Century T:usually
T:now extremely vulnerable to fire L:In the ponderosa pine forests of the West