Battle Flat Watershed Pilot Project

Treatments

Prior to treatment of the Battle Flat Demonstration Area several inventories were done on the control watershed (Tuscumbia) and the watershed to be treated (Battle Flat) in addition to hydrologic instrumentation. These inventories included archaeologic, geologic, vegetation, soils, hydrologic, and wildlife habitat. The vegetation and wildlife inventory was done jointly by the Prescott National Forest, Southwestern Region of the Forest Service, and the Rocky Mountain Forest and Range Experiment Station and coordinated with the Arizona Game and Fish Department.

Once the inventory data were obtained, it was possible to specify the mosaic treatment pattern. This effort included modeling chaparral conversion for water augmentation based on social, economic, and ecological parameters (Hodge et al. 1985). The purpose of the model was to maximize water yield, while constraining the anticipated effects of conversion within selected boundaries. Upper limit constraints were based on nitrate and herbicide contamination of water, and soil erosion due to conversion. Lower, limit constraints were placed on economic benefits associated with increased water yield to ensure cost-effectiveness. This research was used to decide which soil mapping units were appropriate for treatment based on the model. According to this model, about 50 to 55% of the watershed was to be treated in a mosaic pattern similar to that developed for Whitespar A, which was described earlier.

Several nutrient cycling studies on shrubs and soils were done as part of the overall research program. One study was designed to gather prefire data over several years, focusing on plant available nitrogen and phosphorus, and to compare immediate pre- and post-burn levels of available nitrogen and phosphorus (Overby and Perry 1996). This study was coordinated with a study on the effect of aspect and shrub species on the availability and accumulation of nitrogen and phosphorus in soils (Klemmedson and Wienhold 1991a, 1991b). Nutrient and biomass studies were done on shrub live oak and birchleaf mountainmahogany before and after fire (Whysong 1991, Whysong and Carr 1987).

Hydrologic research evaluations consisted of analyzing stream flow data from several permanent gaging stations located on the major drainages and some of the smaller subdrainages in the larger Battle Flat and Tuscumbia watersheds. In addition, stock water tanks were established in two of the smaller watersheds to obtain annual measurements of sediment production. One of these watersheds was prescribe-burned in 1985. Nutrient changes and losses associated with increased erosion resulting from this prescribed burn were also studied (Overby and Baker 1995, Overby and Perry 1996, Hook and Hibbert 1979).

Relatively little was known about the fire history in the chaparral shrublands at the time, although fire suppression records indicated that large fires had been common. The Battle Flat area provided an opportunity to establish the fire history in chaparral stands because vegetation along the drainages contained ponderosa pine trees which could be dated by current tree ring methodologies based on interpreting fire scars on the trunk of ponderosa pine trees (Dieterich and Hibbert 1990). Shrubs do not lend themselves to this analysis because the whole plant is often consumed during a fire. In contrast, during ground fires the basal area of some ponderosa pine trees may be scarred without significantly damaging the trees. Therefore, the close association of ponderosa pine trees with surrounding hillslopes covered with chaparral allowed fire frequencies to be estimated for both the pine and chaparral areas.