AGROFORESTRY POLICIES CONTRIBUTE TO SUSTAINABLE LAND USE

Resource /Energy Economics and Policy,

Efectos de la frecuencia de incendios sobre las cargas de combustible en los bosques de pino-encino de la provincia de Madrean

Loadings of downed woody fuels in pine-oak forests of the Madrean Province are heavier on sites in southeastern Arizona with low fire frequencies and lower on sites in northeastern Sonora, Mexico, with high fire frequencies. Low fire frequencies in southeastern Arizona are attributed largely to past land uses and the fire suppression policies of land management agencies in the United States. Ecologists and land managers interested in reintroducing fire into these forests to reduce fuel loadings and meet other land management objectives could use information about fuel buildups in their planning efforts. Quantifying these fuel loadings could also be useful in improving fire behavior models for the forests

Snowmelt Runoff Efficiencies on Arizona Watersheds

This item is part of the Agricultural Experiment Station archive. It was digitized from a physical copy provided by the University Libraries at the University of Arizona. For more information, please email CALS Publications at [email protected]

Characterization of Arizona snowpack dynamics for prediction and management purposes.

Inventory-prediction equations describing snowpack water content as functions of readily available or easily obtained inventory variables were developed for use in the ponderosa pine type in Arizona. Although empirical in nature, these equations include parameters assumed to index interception of precipitation inputs, obstruction of direct beam solar radiation, and re-radiation from trees onto the snowpack. Primary consideration was given to forest cover variables in synthesizing the inventory-prediction equations I because currently proposed water improvement programs designed to increase water yield derived from snow consist essentially of vegetative manipulations. Additional independent variables evaluated include potential direct beam solar radiation, elevation, soil, and precipitation inputs. All of the inventory-prediction equations describing a particular snowpack condition were not statistically equivalent in terms of the standard error of estimate or the coefficient of determination. Equations including basal area, bole area I volume, and height-index as expressions of forest cover density were generally better than equations with point density, sum of diameters, and number of trees. Inventory-prediction equations developed to describe snowpack dynamics throughout the accumulation period showed similar statistical form, except as possibly attributable to different precipitation inputs. Equations for characterizing residual snowpacks during spring runoff were statistically weak, possibly because factors other than those considered in this study control the runoff process. The inventory-prediction equations were developed to estimate the mean snowpack water content on a basin, and to describe the trade-off , or the rate of exchange, between snowpack water content and forest-site variables on a decision-making unit. The equations do not necessarily predict changes in recoverable water yield resulting from the implementation of a land management system, however. Nonbiotic characteristics of the land, L e., topographic features, geologic formations, and soil . properties, could conceivably control water yield to the extent that changes predicted by the inventory-prediction equations could be masked. Because of limitations in predicting potential changes in recoverable water yield, it was assumed that a land management system that maximizes snowpack water content on site would also provide the maximum potential for increasing recoverable water yield derived from snow. Management guidelines designed to allow snowpack water content to be maximized on site can be formulated within the framework of the inventory-prediction equations, multiple use management constraints, and forest-based product benefits and costs. Management guidelines indicate that the greatest gain in snowpack water content on site would be realized on decision-making units where the greatest reduction in forest cover density could be prescribed. However, a timber production constraint may limit the array of management possibilities. This constraint was defined as 35 to 40 square feet of basal area or 1,050 to 1,175 cubic feet of volume per acre, depending upon the existing growth percent and the intermingling of tree volumes and size classes. The potential increase in snowpack water content on site will be determined by the magnitude of the reduction in forest cover density and how close management re-direction can approach the timber production constraint. The proportion of the snowpack water content on site converted to recoverable water yield is dependent upon the runoff efficiency.hydrology collectio

Extrapolation of Water-Yield Improvement Studies on Upland Watersheds to Larger River Basins

From the Proceedings of the 2007 Meetings of the Hydrology Section - Arizona-Nevada Academy of Science - March 31, 2007, Nothern Arizona University, Flagstaff, ArizonaThis article is part of the Hydrology and Water Resources in Arizona and the Southwest collections. Digital access to this material is made possible by the Arizona-Nevada Academy of Science and the University of Arizona Libraries. For more information about items in this collection, contact [email protected]

A Brief Summary of a Report by the National Research Council on the Hydrologic Impacts of Forest Management

From the Proceedings of the 2009 Meetings of the Hydrology Section - Arizona-Nevada Academy of Science - April 4, 2009, University of Arizona, Tucson, ArizonaThis article is part of the Hydrology and Water Resources in Arizona and the Southwest collections. Digital access to this material is made possible by the Arizona-Nevada Academy of Science and the University of Arizona Libraries. For more information about items in this collection, contact [email protected]

Land Stewardship in the 21st Century: the Contributions of Watershed Management: Conference Proceedings, Tucson, Arizona, March 13-16, 2000

The conference proceedings include studies on watershed management, on the Southwest and Colorado Basin, as well as reports by Arizona researchers. The microfiche version is also available in the Arizona State Library and Archives' Federal Publications collection