Significance of Extreme or Intermittent Conditions in Distribution of Species and Management of Natural Resources, with a Restatement of Liebig's Law of Minimum

Action of the environment on the organism or the biotic community is not uniform or consistent. Unusual features are quite normal. Extreme conditions are probably more significant in appraising action of environment than are the more ordinary environmental relationships. Extremes of greatest importance are those of temperature (heat or cold), moisture (drouth or flood), and wind, although effective extremes might develop in any other fluctuating environmental factor. The whole subject needs further study. As Patton ('30) says, species are not adapted to average conditions, but to the exceedingly unfavorable conditions experienced from time to time.