Thermodynamic law for adaptation of plants to environmental temperatures

A thermodynamic law of adaptation of plants to temperature is developed. Plant growth rate is proportional to the product of the metabolic rate and the metabolic efficiency for production of anabolic products. Over much of the growth temperature range, metabolic rate is proportional to mean temperature and efficiency is proportional to the reciprocal of temperature variability. The mean temperature and short-term (hours to weeks) variability of temperature during the growth season at a particular location thus determine the optimum en- ergy and growth strategy for plants. Because they can grow and reproduce most vigorously, plants with a growth rate vs. temperature curve that matches the time-at-temperature vs. tem- perature curve during the growth season are favored by natural selection. The law of tem- perature adaptation explains many recent and long-standing observations of plant growth and survival, including latitudinal gradients of plant diversity and species range.