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Grass, Brush, Timber, and Fire in Southern Arizona [1924] This classic of ecological analysis may have been Leopold's response to his colleagues ' criticism of his treatment of the erosion problem in "Some Fundamentals of Conservation in the Southwest." Through careful observation and inferential reasoning , he develops an interpretation that integrates soils, vegetation, topography and climate, geologic and human history, fire, and livestock grazing into a single system of interactions. In this pathbreaking article published in the Journal of Forestry, he directly challenges a number of Forest Service dogmas, particularly those concerning the role ofgrazing and fire, and calls for a redirection of administrative policy. One ofthe first things which a forester hears when he begins to travel among the cow-camps of the southern Arizona foothills is the story of how the brush has "taken the country." At first he is inclined to classify this with the legend, prevalent among the old timers of some of the northern states, about the hard winters that occurred years ago. The belief in the encroachment of brush, however, is often remarkably circumstantial. A cow-man will tell about how in the 1880's on a certain mesa he could see his cattle several miles, whereas now on the same mesa he can not even find them in a day's hunt. The legend of brush encroachment must be taken seriously. Along with it goes an almost universal story about the great number of cattle which the southern Arizona foothills carried in the old days. The old timers say that there is not one cow now where there used to be 10, 20, 30, and so on. This again might be dismissed but for the figures cited as to the brandings of old cattle outfits, of which the location and area of range are readily determinable. This story likewise must be taken seriously. In some quarters the forester will find a naive belief that the two stories represent cause and effect, that by putting more cattle on the range the old days of prosperity for the range industry might somehow be restored. 114 Grass, Brush, Timber, and Fire 115 The country in which the forester finds these prevalent beliefs consists of rough foothills corresponding in elevation to the woodland type. Above lie the forests of western yellow pine. Below lie the semi-desert ranges characteristic of the southern Arizona plains. The area we are dealing with is large, comprising the greater part of the Prescott, Tonto, Coronado, and Crook National Forests as well as much range outside the Forests. The brush that has "taken the country" comprises dozens of species, in which various oaks, manzanita, mountain mahogany and ceanothus predominate. Here and there alligator junipers of very large size occur. Along the creek bottoms the brush becomes a hardwood forest. Five facts are so conspicuous in this foothill region as to immediately arrest the attention of a forester. (1) Widespread abnormal erosion. This is universal along watercourses with sheet erosion in certain formations, especially granite. (2) Universal fire scars on all the junipers, oaks, or other trees old enough to bear them. (3) Old juniper stumps, often levelled to the ground, evidently by fire. (4) Much juniper reproduction merging to pine reproduction in the upper limits of the type. (5) Great thrift and size in the junipers or other woodland species which have survived fire. A closer examination reveals the following additional facts: First, the reproduction is remarkably even aged. A few ring counts immediately establish the significant fact that none of it is over 40 years old. It is therefore contemporaneous with settlement; this region having been settled and completely stocked with cattle in the 1880's. Second, the reproduction is encroaching on the parks. These parks, in spite of heavy grazing, still contain some grass. It would appear, therefore, that this reproduction has something to do with grass. Third, one frequently sees manzanita, young juniper or young pines growing within a foot or two of badly fire-scarred juniper trees. These growths being very susceptible to fire damage, they could obviously not have survived the fires which produced the scars. Ring counts show that these growths are less than 40 years old. One is forced to the conclusion that there have been no widespread fires during the last 40 years. Fourth, a close examination of the erosion indicates that it, too, dates back about 40 years and is therefore contemporaneous with settlement, removal of grass, and cessation of fires. These observations...

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