HYDROLOGIC RESPONSES OF SPRING-FED HART PRAIRIE WATERSHED IN SEMI-ARID NORTHERN ARIZONA TO FOREST RESTORATION

Early anthropogenic landscape and land cover modifications are believed to have led to a deleterious decline in groundwater availability to a rare high-elevation Bebb Willow community (Salix bebbiana) and the meadow landscape it resides in. This 26-year study determined the hydrologic response of groundwater recharge and spring discharge, due to the watershed restoration treatments in the spring-fed Hart Creek in the Hart Prairie watershed. Preliminary results indicate that forest restoration treatments can lead to an increase in groundwater recharge and spring discharge. The study supports the U.S. Forest Service to restore 2.4 million acres of overly dense, fire-adapted forest ecosystems in Northern Arizona through the Four Forest Restoration Initiative (4FRI). The primary goal of this restoration project is to improve the resiliency of the forest ecosystems by conducting mechanical thinning and prescribed burning.

Analyses of the data involved both qualitative and quantitative methods of pre- and post-forest management treatments. Hydrologic data were collected and compiled, and used to calculate annual hydrographs. Precipitation and annual runoff data were used to create a multilinear regression model of the hydrologic response pre- and post-restoration treatment. ArcGIS was used to create a Hart Prairie Spring watershed map and tree canopy coverage map prior to and following restoration.

The characteristics of the forested ecosystem range from an increase in tree density, an increase in fire severity, a decrease in growth and biodiversity of herbaceous and woody plants, and a decrease in stream and spring flow. However, ecohydrogeologic restoration efforts have increased the number of flowing days for Hart Prairie Springs. These results indicate that groundwater recharge responds positively to restoration actions. Further analyses and climate data are needed to determine and verify the effectiveness of forest restoration in Northern Arizona, leading to increased groundwater recharge and spring discharge and ecological functionality.