PARENT SESSION
Symposium #24: Adaptive Management Experimentation in Ponderosa Pine Forest Restoration.
Organized by: PZ Fule and PG Friederici
Wednesday, August 7. 1:00 PM to 4:30 PM. Maricopa Meeting Room, TCC.
Water, nutrient, and carbon fluxes following ecological restoration of southwestern ponderosa pine forests.
HART, STEPHEN*,1, KAYE, JASON2, COVINGTON, W.1, FULE, PETER1, MOORE, MARGARET1, 1 steve.hart@nau.edu, Flagstaff, AZ2 Colorado State University, Fort Collins, CO
ABSTRACT- Despite the widespread application of thinning and prescribed burning restoration treatments in southwestern ponderosa pine forests, there are few experimental tests of restoration effects on ecosystem function. We measured water, carbon, phosphorus, and nitrogen cycling for two years following a replicated field application of control (untreated), partial restoration (thinning), and complete restoration (thinning, forest floor manipulation, and prescribed burning) treatments. Simulated water yield from restoration treatments was 50 to 100% greater than the control. Net nitrogen mineralization increased similarly in the partial restoration treatment, but complete restoration did not consistently increase nitrogen mineralization. Nitrogen mineralization rates were comparable to plant uptake (30 kg N/ha/y in all treatments) following partial restoration, but lower than plant uptake in control and complete restoration treatments. Total net primary production (2600 kg C/ha/y) was similar among treatments, but this whole-ecosystem response masked important within-system dynamics. Aboveground herbaceous and wood production were greater (500 and 50%, respectively) and tree fine root production was lower (50%) in restoration treatments than the control. Consequently, trees accounted for 80% of plant nitrogen and phosphorus uptake in the control, while in restoration treatments nutrient uptake was balanced between tree (50 to 66%) and herbaceous (33 to 50%) components in the final measurement year. These forests are important sources of water, forage, wood, and carbon sequestration; many of these services were retained in restored ecosystems.
KEY WORDS: ecological restoration, nutrient cycling, water balance, net primary productivity