Semidesert rangeland before and after brush control. Reviving Copyright © 1983 Soil and Water Conservation Society. All rights reserved. Arizona’s Journal of Soil and Water Conservation rangelands By Jerry R. Cox, Howard L. Morton, Jimmy T. LaBaume, and Kenneth G. Renard, ISTORICAL records show that tions of land with precise areas. Early and 1880 (38). Furthermore, some 2,000 southeastern Arizona was a grass- American explorers, on the other hand, cows continuously grazed the Santa Cruz 38(4):342-345 land before 1880. Today, shrubby maintained journals describing vegetation Valley between Sahuarita and Tucson be- plants dominate the region. From 1880 to and location. Their records provide de- fore 1870, and about the same number also 1900, dramatic changes in the composition scriptions of grazing areas and vegetation grazed the Tanque Verde, Pantano, and of vegetation took place along major wa- in southeastern Arizona prior to 1870: Rillito grasslands during the same period. terways. Flooding and resulting channel- Santa Crux Basin. “We were off this San Pedro Basin. “The valley of thiswww.swcs.org ization, plowing of the floodplains, and morning [from Tucson]. .and soon entered river is quite wide and is covered with a livestock grazing essentially eliminated the a thickly wooded valley of mesquite. A ride dense growth of mesquite, cottonwood and natural process of shallow groundwater re- of nine miles brought us to San Xavier de willow. The majority of the valley has charge. Changes in vegetation on upland Bac ...a mile further we stopped in a fine good grass.. .the bottoms having very tall range between 1930 and 1980 were grad- grove of large mesquite trees near the grass. There is excellent trout fishing but ual but just as destructive. We documented river, where there was plenty of grass. The the grass makes travel by wagon very diffi- the changes in the region’s vegetation be- bottom-lands resembled meadows being cult” (7). tween 1880 and 1980, determined why the covered with luxuriant grass and but few Sulphur Springs Basin. “This vast area changes occurred, and determined if the trees. The bottoms [between San Xavier is without either running streams or tim- range resource can be reclaimed. and Tubac] in places are several miles ber, but covered to a great extent with fine wide.. .and covered with tall, golden col- grass. Approaching Sulphur Springs from Early descriptions ored grass.. .divided by a meandering the East, the road lies for miles through a stream a dozen yards wide and as many dense growth of sacaton grass” (16). This Spanish explorers and ranchers were ac- inches deep, this shaded by cottonwoods, area was particularly adapted to grazing tive in southeastern Arizona (3, 12, 38), willows, and mesquites” (4). because of climate, abundance of alkali but it is difficult to correlate their descrip- The upland range [south and east of sacaton and salt grass in the playas, and Tucson] provided excellent summer and grama grass on the uplands (11). Jery R. Cox is a range scientist and Howard winter forage of grama grass, indian- Sun Simon Basin. “The valley of the San L. Morton is a supervisoy plant physiologist with the Agricultural Research Service, U.S. wheat, and winter annuals in 1900 (11). Simon is ...25 miles in width, and contains Department of Agriculture, 2000 East Allen Considering current vegetation and soil much fine grazing and some agricultural Road, Tucson, Arizona 85719. Jimmy T. La- conditions it may be difficult to visualize land. It is covered with grama grass. Mes- Baume is a consulting range scientist, now resid- the Santa Cruz Valley near Tucson cov- quite is most conspicuous and abundant ing in Alpine, Texas 79830. Kenneth G. Renard ered with grass. However, 100 cows con- from the base of the mountain [Graham]. b a research hydraulic engineer with ARS, . USDA. 422 East Seventh Street, Tucson, tinuously grazed a big sacaton pasture of and sparse on the mesa.. .the sacaton and Arizona 85705. about 100 acres near Tucson between 1868 grama cover the plain.. The county 342 Journal of Soil and Water Conservation abounds in game, such as deer, antelope, wet and dry years. In fact, annual varia- wolf, wild turkey, duck and quail” (16). tions in precipitation were greater in southeastern Arizona than in any other The livestock industry part of the contiguous United States (13). The variability of individual storms and With the completion of southwestern total annual rainfall was illustrated at the railroads and dangers from Indian raids re- Walnut Gulch Experimental Watershed in duced, stockmen from Texas and investors 1967 (23,24).Annual rainfall was 10 inch- from England and the eastern United es at one location and 16 inches at another. States moved large herds of cattle and The distance between the locations was less sheep into southeastern Arizona in search than 10 miles. Thus, a wet year and a dry of “free grass” (11, 38). The winter of 1888 year occurred in the same general area. and summer of 1889 were wet and forage annual rainfall on upland range A sacaton stand near Tucson in 1902. was abundant. More cattle and sheep were would directly affect forage production. shipped from the Great Basin the following However, runoff from locations where winter. By 1891 there were an estimated rainfall was above average would accumu- 1.5 million cattle in Arizona’s southeastern late in lowlands every year and forage pro- counties (Table 1). duction would remain relatively stable. Summer and winter rains were well be- Before channelization in lowlands oc- low normal in 1891, and by June 1892 cat- curred, water entering major channels was tle began to die. The governor of the naturally spread over large areas by dense Arizona Territory estimated losses at 50 to stands of sacaton. As a result, water moved Copyright © 1983 Soil and Water Conservation Society. All rights reserved. 75 percent (11, 18). Another report noted, slowly in channels, shallow aquifers were Journal of Soil and Water Conservation “In my past trip [Vail, Arizona, to likely replenished each year, and discharge Nogales, Mexico] beef carcasses were so occurred over months rather than hours. numerous that they dotted the landscape.. Between 1904 and 1914, summer rain- it is not possible to travel more than a fall was apparently above average (40), stones throw without seeing bones or de- forage was abundant, cattle prices were caying bodies of cattle” (28). high, shipping costs declined, and ranges A typical overgrazed hillside in south- Historians generally assume that live- were overstocked. A brief dry period oc- eastern Arizona in 1933. stock populations before 1900 were equally curred in 1917. There was severe drought distributed throughout southeastern in 1920. In the summer of 1933, southeast- Arizona. Livestock no doubt followed ern Arizona counties were classified as minor drainages and grazed the uplands in emergency areas, and the Bureau of 38(4):342-345 wet years. But upland water development Animal Industry condemned and slaugh- and fencing began after 1930 (38), and tered range cattle (38). livestock grazing was likely limited to areas Passage of the National Industrial Re- near major drainages and playas in the covery Act and implementation of the 1890s. If this assumption is true, livestock Work Progress Administration and www.swcs.org use was limited to about 20 percent of the Civilian Conservation Corps in the 1930s land area (3.6 million acres), and livestock led to the opening of new grazing land. grazing was concentrated in sacaton bot- Federal and private groups developed toms and on nearby grama uplands. water on upland range, and fencing was Alkali sacaton (Sporobolus airoides) and used to divide land into grazing units (19). big sacaton (Sporobolus wrightii) were Range livestock populations that were pre- common before 1900. The plants covered viously confined to lowlands were then A retake of above scene in 1980, alluvial floodplains and nearby uplands in moved to upland range. showing increase of brush, cactus. southern Arizona and New Mexico (17). From 1890 to 1980, wet periods with Could these grasses, covering 20 percent of abundant forage were followed by over- the land, support 1.5 million cattle? stocking, and drought periods were fol- In a wet summer, when rainfall exceed- lowed by livestock reductions. With each ed 10 inches, both sacaton species pro- successive cycle, perennial grass productiv- duced up to 3 tons per acre of green forage. ity declined, and the rangeland supported But in a dry summer, when rainfall was fewer livestock. Excessive and continuous less than 5 inches, sacaton produced less use of perennial grass slowed plant re- than 1 ton per acre of green forage. In wet covery and favored invasion of woody years, or those before 1891, 20 percent of plants. Semidesert grassland became semi- the land area might have supported more desert shrubland (10, 11, 12, 18). than 1.5 million cattle. However, in dry If livestock populations have declined 88 years (1891 to 1893), the same area would percent over the past 90 years and if re- support 500,000 head or less. duced forage production caused channel- Annual precipitation varies greatly in ization, then one might logically assume southeastern Arizona, adding to the com- that cattle grazing caused the decline in Recent photo of a productive sacaton plexity of estimating forage production in forage production and is responsible for meadow with trees. JUly-AuguSt 1983 343 channelization. Unfortunately, overgraz- mum cultivation (by county), about 2.6 in the 1970s and early 1980s, but mining ing continues to occur in southeastern Ari- million acres were cultivated in the five and urban uses are accelerating in Pima zona, but it is incorrect to infer that the southern counties; and if the areas farmed County (2).