Abstracts of Papers Presented

ABSTRACTS OF PAPERS PRESENTED EARL B. ALEXANDER, USDA Forest Service, Alaska Region, Juneau, Alaska Soils Information Utilized in Management of the Tongass National Forest, Southeast Alaska The 1.6 million-acre Tongass National Forest is the largest national forest in the United States. Timber, wildlife, fisheries, mining, and recreation are the main management concerns. Soils have been mapped at 2 inches per mile or smaller scales in all butWilderness Areas and National Monuments on the Forest, and the data have been entered into a geographical information system (GIS). The soils, in orderof areal extent, are Spodosols, Histosols, Inceptisols, andEntisols. Potential natural plant communities have been described and plant series or associations identified on the soils; thus the soils delineations serve forplantcommunity maps. Soil map units and wetlands maps have been made by combining soils and plant community data in the GIS. The most important interpretations of these maps concern productivity for timber and mass failure hazard. Soil maps provide the mainnatural resourcebase in landmanagementplanning on theForest, theirvalues being enhanced with plant community data which can be related to the soils. JAMES G. ASHBAUGH, Portland State University, Portland, Oregon Instructor Produced Video in Teaching Geography The video cameracan be a useful instructional tool for teachers of geography. It does not replace photo transparencies and overhead and opaque projectors but ratheraugments these and othermethods of visually portraying geography. Like a motion picture, video shows movement and the flow of activities in a way that cannot be duplicated by a 35mm camera. It is also much less expensive and more flexible than, for example, a 16mm movie camera. Video tape is inexpensive and can be edited and erased. The initial cost may be $1000, but expensive developing of 16mm film is eliminated. Thepaperdiscusses equipment,costs ofgetting started in making video forclassroom instruction, andproduction,editing, andsound tech­ niques. I show examples of video tape I have made in the U.S., Canada, Mexico, and England for use in my classes. 234 ABSTRACTS 235 ROBERT C. BALLING, JR. and TOMAS A. MILLER, Arizona State University, Tempe Climatic Impacts of Differential Overgrazing Along the Arizona and Sonora Border The international border between the states of Arizona and Sonora is marked by a sharpdiscontinuity in the semi-aridgrasslandvegetation. Since thepassage of the Taylor Grazing Act in 1934, grazing in the United States has been controlled; severe overgrazing has occurred throughoutmuch ofnorthernMexico. As aresult, the Mexican land is characterized by shorter grasses, more bare soil, and a higher albedo when compared to adjacent land in the United States. In this investigation, an integrated approach involving satellite observations, field measurements, and historical climatic datareveals the climatic impact of the vegetation discontinuity. Significantly warmeranddrierconditions on the Mexican side combine to enhance evapotranspiration rates, thereby generating positive feedback for further deserti­ fication of the landscape. The results suggest that overgrazing in other semi-arid areas of the world can lead to drier conditions, notby retarding rainfall, but rather by increasing local evapotranspiration rates. TERESA L. BULMAN, University of California, Davis Conjunctive Water Use in Napa County, California: The Role of Private Reservoirs The study provides a spatial analysis of privately owned reservoirs in Napa County, California, and analyzes the function of privately owned reservoirs in conjunctive water use in the county. Privatereservoirs areplaced in the context of NapaCounty’s regional geography, including topography,climate, hydrology and water resources, water projects, historical and present land use, and institutional arrangements. Despite the regional economic importance of vineyard operations, which are dependent on ground water and private reservoirs for water supply, regional institutional barriers inhibit the incorporation of private reservoirs into regional water policy processes. Hood control regulations, “buffer zone” ordi­ nances, and increased water storage by the incorporated areas have restricted the development, location,anduseofprivatereservoirs. Inordertoprojectfuturewater needs and to develop alternative water plans for Napa County, water resources managers need to understand the role of private reservoirs. JANET S. CLEMENS, University ofAlaska, Anchorage Myth or Reality: the Battle over Alaska’s Agricultural Destiny Large-scale commercial agriculture in Alaska has yet to succeed. Historian RichardHofstadterandgeographerJames Shortridge have shown how theagrarian ideal played a vital role in the early development of western frontiers. This ideal, however, increasingly lost its applicability from the late 19th...