Effects of grazing upon bunch wheat grass

Agropyron inerme was studied on range land in Cache Valley, Utah. Studies were made on protected and heavily grazed areas to compare root development, herbage and seed production, and content of sugar, starch, and hemicellulose in roots and stem bases. The habits of growth of the roots of Agropyron inerme are well adapted to its habitat and insure the species a place as dominant in the area studied. The soil mass below normal plants was thoroughly permeated from a depth about 5 cm to as deep as 180 cm. Root weight was 13.1 times top weight. The average weight of roots per cubic decimeter of soil was 25.85 grams on protected range and 4.22 grams on heavily grazed range, a reduction to about one-sixth the normal. Maximum depth of roots of grazed plants was materially reduced. There was a very marked decrease in the above-ground parts of wheatgrass accompanying overgrazing as evidenced by reduced basal area, height, and number of seed stalks. Germination tests of filled florets taken from protected and heavily grazed range showed no significant difference. On protected range 38.8% of the florets matured and on heavily grazed range 23.9% matured. There were 630.2 viable seeds per square meter of ground produced on protected range and 12.2 on the heavily grazed area. Stem bases and roots of plants protected from heavy grazing in previous years contained 17.77% sugar and starch, while those of plants grazed heavily in previous years contained 14.33%. The hemicellulose content was not significantly different. This study leads one to conclude that Agropyron inerme could have been dominant on much range land in Cache Valley where it is at present scarce or wanting, and general observations indicate that it was dominant. Sustained yield of A. inerme depends predominantly upon extent, intensity of ramification, and carbohydrate content of the root system. This study emphasizes the importance of controlled grazing.