Contributions of Silvicultural Studies at Fort Valley to Watershed Management of Arizona’s Ponderosa Pine Forests

Watershed management and water yield augmentation have been important objectives for chaparral, ponderosa pine, and mixed conifer management in Arizona and New Mexico. The ponderosa pine forests and other vegetation types generally occur in relatively high precipitation zones where the potential for increased water yields is great. The ponderosa pine forests have been the subject of numerous research and management activities. Although the size, topography, and drainage patterns of the Fort Valley Experimental Forest are not conducive to watershed-scale hydrologic studies, results from Fort Valley have demonstrated the potential of silvicultural options to increase water yields. These included creating openings of different sizes, shapes, and orientations, or reducing stand densities or combinations of the two. While the importance of managing forests for water yield improvement has declined, it is still a consideration in multi-resource planning. This paper reviews silvicultural prescriptions employed on some of the major watershed research studies within the ponderosa pine forests and discusses their management implications. results from the long history of silvicultural studies on the Fort Valley Experimental Forest (Pearson 1950, Schubert 1974, and other researchers1) provided the basic foundation for prescribing water yield improvement options to test in the ponderosa pine forests on the Beaver Creek and Castle Creek watersheds (Figure 1). The four case studies presented below describe some of the silvicultural treatments imposed on these watersheds and the results and conclusions. They also suggest options available for multi-resource forest management. Further details of these and other water-yield improvement treatments based on Fort Valley silvicultural studies and the results are found in the literature that evolved from these efforts and at the web-site: http://ag.arizona.edu/ OALS/watershed/.