In 1920 there was a significant plunge in the rate of growth in this tree’s life. It is known that the Pseudotsuga menziesii is sensitive to drought, thus it could have been one of the many reasons why the growth rate changed dramatically. The decrease in growth continued in 1960 to 1970 where the growth rate was at its lowest. Rocky mountainous slope that is the habitat of Douglas fir, can get congested at times and this can aid in the loss of growth rate. 1980 recorded a small increase in growth, insect infestation, natural disasters and forest fires among others. This may have destroyed some of the competition that surrounded the tree, giving the Douglas fir more space to grow.
