I am analyzing a series of plots along a recovery gradient, using "time since disturbance" as a continuous variable. I want to see how certain environmental variables change with time since disturbance and was thinking of using regression - however I also have plots that were never disturbed, so their time since disturbance is basically infinite. Is there a way to include these "infinite" values in the same regression? If not, is there a better way to compare undisturbed plots to plots experiencing a range of different recovery times?

been looking at stats textbooks without much luck - any suggestions appreciated!