Seasonal Changes in Bound Water Content of some Prairie Grasses

Abstract

A study of the bound and free water content of several components of I. Upland prairie (Bouteloua gracilis, Stipa comata, Carex filifolia and Andropogon smithii); II. Sagebrush type (Artemisia cana, and Stipa viridula); III. Sandgrass type (Calamovila longifolia, Carex filifolia, C. eleocharis, C. pennsylvanica, and Koeleria cris-tata); and IV. Big bluestem type (Andropogon furcatus, Stipa spartea, and Bouteloua curtipendula) in western N. Dakota using the calorimetric method indicated that the bound water %, % free water, and grams of free water per 100 g. of dry matter gave the best expression of the responses of the species to the conditions of their habitats. The % bound water in a species was apparently a reflection of the relative degree of dryness of the habitat and not a measure of the inherent adaptation of that species to a dry habitat because the absolute amt. of bound water, expressed as g. per 100 g. of dry matter, remained at approx. the same characteristic level in the species during the season. The increases in bound water as % of the total water resulted from losses in free water caused by progressive drying of the plant tissues and not from increases in the water-retaining capacity of the leaves.