Castle Creek Watersheds - Results and Current Status
Results from the harvesting treatment in predominately ponderosa pine
on Castle Creek, West Fork were:
An annual average water yield increase of about 30%, or 0.5 inch,
was attributed to reduced evapotranspiration and increased snow accumulations
in the openings.
Evapotranspiration was lowered by 4 inches (19 to 15 inches).
Increased water yield remained stable for 21 yr (1967 to 1987), probably
because new tree roots had not fully occupied the soil mantle, and the
height differences between the residual trees surrounding the openings
and the regeneration continued to provide aerodynamics that favored
increased snow accumulations in the openings.
Effects on wildlife were important. The mixture of forest and interspaced
clearcut blocks provided excellent conditions for deer and elk.
Results of prescribed fire on Castle Creek, East Fork included:
No increase in average annual water yields, which was understandable
because the fire did not affect forest overstory conditions or consume
much of the forest floor.
Concentrations of NH4-N and NO3-N, PO4, and K increased during the
first 2 post-fire snowmelt periods. The changes in nutrient concentrations,
while statistically significant, were small and of little consequence
in terms of site productivity and downstream water quality.
Most of the watershed experiments were terminated between 1983 and 1986.
However, the Apache-Sitgreaves National Forest continues to collect streamflow
and precipitation measurements from the Castle, Willow, and Thomas Creek
Watersheds as part of its hydrological monitoring program. The vegetation
transects and points continue to be visited by USDA forest pathologists
to determine changes in dwarf mistletoe infections over time. Additional
inventories are being considered by scientists at the Rocky Mountain Research
Station. Data from the watersheds have also been used by graduate students
at the University of Arizona.