Contrasting Effects of Big Sagebrush and Rubber Rabbitbrush on Production of Crested Wheatgrass

Abstract

Big sagebrush (Artemisia tridentata) and rubber rabbitbrush (Chrysothamnus nauseosus) have increased greatly under all grazing treatments on the Benmore Experimental Range in west central Utah (Frischknecht et al. 1953). Whereas it is generally considered that both species reduce grass yields, this paper reports results of three correlated studies of grass clipping showing that they differ markedly in their effects upon production of crested wheatgrass. In a general way, results are related to differences in brush root systems and growth habits. The competitive relationship between big sagebrush and grass is well documented. Nearly 20 years ago Pechanec et al. (1944) and Robertson and Pearse (1945) recognized that successful establishment of artificial seedings depended upon successful eradication of sagebrush. Blaisdell (1949) observed that when grass and sagebrush became established at the same time, grass had the initial advantage but sagebrush eventually gained a prominent place in the stand. Sagebrush had the advantage from the start when it became established before grass. Less information is available about competition between rubber rabbitbrush and grass. McKell and Chilcote (1957) observed that growth and seed production of rubber rabbitbrush increased when competing vegetation was removed. Plummer et al. (1955) listed both rabbitbrush and sagebrush among the undesirable competition to be eliminated to assure success of introduced grass in range seedings. They reported that successful plantings had been made into thin stands of rabbitbrush. These authors and others have emphasized that rubber rabbitbrush is more difficult to control than big sagebrush because it habitually resprouts. brush stump and over each remaining brush plant. The cages protected grass from being grazed on circular plots 9.6 square feet in area, centered at the brush stems; plot size was selected largely for convenience in expressing yields in pounds per acre (Frischknecht and Plummer, 1949). In addition, two nearby randomly located grass plots without brush were similarly protected from grazing in each pasture. Three months later, after spring growth was completed, grass on each plot was hand-clipped, air-dried, and weighed. Simple “t” tests were applied to yield data.