Although you have not given the options regarding this question, but still i am trying to answer as correctly as possible. There were definite drastic changes in the environment due to westward railroad expansion. Firstly the trees were cut down for getting the lumber. The lumber was used for making bridges and placing the rail tracks. So there was destruction of natural forests. Secondly the number of naturally found buffaloes started decreasing immensely. So this created a natural imbalance in that region. There was a lot of wastage as far as natural resources were concerned.