Interpretation of global differences in plant calorific values : The significance of desert and arid woodland vegetation.

Calorific values for the vegetative tissues of a group of perennial desert and arid woodland plants ranged from 3,191 to 5,375 calories per gram, oven dry weight. These span the range of comparable values reported earlier for plants in other environments, and reflect variety in adaptations to dry environments. Tissues with low values had high ash percentages, and contain significant amounts of low-energy oxalate salts. To interpret differences in calorific values for plants, one must understand: 1) the significance of calorific values in plant energetics, 2) the functions of compounds responsible for high and low values, and 3) the relative rates of metabolism and dry matter production for those plants.