Effects of Fire on Water Infiltration Rates in a Ponderosa Pine Stand

From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, ArizonaThe importance of pine forest as a timber and water producing area has led to intensive management, including protection from wildfire. This has resulted in dense stand growth with increased destructive fire potential and transpirational water loss. In Arizona, as in many areas, prescribed forest burning has been used to effectively reduce these fuel hazards. Some question has arisen about the possible side effects of such treatments, particularly air pollution and reduction of infiltration and water yield. In an effort to determine the effects on infiltration, plots receiving various treatments (control, light burn, heavy burn) were fitted with fusion pyrometers before burning, to measure soil surface temperatures during burning. After burning, infiltrometers were installed. Surface temperatures did not exceed 200 degrees f. For the light burns, and ranged over 350-500 degrees f. During heavy burns. Both heavy and light burns produced highly significant decreases in infiltration capacities after burning and the surface 2 inches showed increases in soil pH, carbon and total nitrogen percentages. Infiltration capacities returned to normal after overwintering and were attributed to frost action on soil texture and porosity. The soil chemical changes decreased slowly over 2 years. Soil water repellency also increased and the significance of this is discussed.This 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 anashydrology@gmail.com