. 0 1 1 Sagebrush 50 1 Coniferou 100 Miles 1 J 1 j Desert scrub forest | Alpine Grassland | I ] Saxlcoline brush ! 7J Pirion-Juniper meadow, fellfield Fig. 7. Vegetation map of Colorado (modified from map, "Major land resource area and generalized land use map—Colorado," Department of Agriculture, Soil Conservation Service, Portland, 1969). evidence that heavy grazing pressure has been part of the set of selective forces molding the adapted constitutions of these species. Similar disagreements might be cited with regard to the importance of fire in the mainte- nance of the clima
. 0 1 1 Sagebrush 50 1 Coniferou 100 Miles 1 J 1 j Desert scrub forest | Alpine Grassland | I ] Saxlcoline brush ! 7J Pirion-Juniper meadow, fellfield Fig. 7. Vegetation map of Colorado (modified from map, "Major land resource area and generalized land use map—Colorado," Department of Agriculture, Soil Conservation Service, Portland, 1969). evidence that heavy grazing pressure has been part of the set of selective forces molding the adapted constitutions of these species. Similar disagreements might be cited with regard to the importance of fire in the mainte- nance of the climax. Such arguments fre- quently tend to over-emphasize parts of the holocenotic environment, to neglect the dy- namism of grassland communities, and to un- derestimate the role of natural disturbance. According to Weaver and Albertson (1956: 25): "When the pioneers came from the East to make their homes in the Great Plains re- gion, they found a dense cover of native vege- tation. It was disturbed only by buffaloes, prairie dogs, other plains animals, Indians, and prairie fires" (italics mine). The dynamism of vegetation has its source in the differences in the tolerances of various species, and the consequent semi-independent responses of various species to fluctuations in the plains environment. The point was made explicit by Kiichler (1968) in a discussion of problems inherent in mapping dynamic vege- tation within static boundaries, stressing the ecological bases of the observed dynamism.
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectmammals
