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ARS Home » Pacific West Area » Burns, Oregon » Range and Meadow Forage Management Research » Research » Publications at this Location » Publication #149927
Title: LONG-TERM HYDROLOGIC RECOVERY FOLLOWING REMOVAL OF WESTERN JUNIPER

Author
item Pierson Jr, Frederick
item Bates, Jonathan - Jon
item Svejcar, Anthony

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Other
Publication Acceptance Date: 8/20/2002
Publication Date: 2/20/2003
Citation: PIERSON JR, F.B., BATES, J.D., SVEJCAR, A.J. LONG-TERM HYDROLOGIC RECOVERY FOLLOWING REMOVAL OF WESTERN JUNIPER. SOCIETY FOR RANGE MANAGEMENT MEETING ABSTRACTS. 2003.

Interpretive Summary: EXPANSION OF WESTERN JUNIPER WOODLANDS IN THE SAGEBRUSH STEPPE CAN DRAMATICALLY CHANGE PLANT COMPOSITION, REDUCE UNDERSTORY VEGETATION PRODUCTION AND CONSEQUENTLY NEGATIVELY IMPACT THE HYDROLOGIC RESPONSE OF A SITE. CUTTING OF WESTERN JUNIPER CAN POTENTIALLY RESTORE THE UNDERSTORY VEGETATION AND IMPROVE A SITE¿S HYDROLOGIC CONDITION. LITTLE IS KNOWN ABOUT THE RATE OF HYDROLOGIC RECOVERY OR THE DEGREE OF UNDERSTORY NEEDED TO ADEQUATELY PROTECT A SITE FOLLOWING JUNIPER REMOVAL. THE OBJECTIVE OF THIS STUDY WAS TO QUANTIFY THE LONG-TERM IMPACT OF CUTTING WESTERN JUNIPER ON INFILTRATION, OVERLAND FLOW DYNAMICS, RILL AND INTERRILL EROSION RATES. LARGE-PLOT RAINFALL SIMULATION AND RILLING PROCEDURES WERE USED TO COMPARE INFILTRATION, RUNOFF AND EROSION RATES BETWEEN JUNIPER CUT AND UNCUT PLOTS TEN YEARS AFTER JUNIPER CUTTING. THE JUNIPER DOMINATED (UNCUT) PLOTS BEGAN TO RUNOFF AFTER RAINFALL WAS APPLIED EQUIVALENT TO A TWO-YEAR RETURN PERIOD THUNDERSTORM. JUNIPER CUT PLOTS DID NOT RUNOFF UNTIL THE EQUIVALENT OF A 100-YEAR RETURN PERIOD THUNDERSTORM WAS APPLIED. THE UNCUT PLOTS ALSO PRODUCED HIGH QUANTITIES OF INTERRILL AND RILL EROSION COMPARED TO NEAR ZERO LEVELS MEASURED ON THE PLOTS WHERE JUNIPER HAD BEEN REMOVED. TEN YEARS FOLLOWING JUNIPER CUTTING, JUNIPER INDUCED REDUCTIONS IN UNDERSTORY CANOPY COVER, GROUND COVER (LITTER, BASAL COVER, ETC.), SOIL ORGANIC MATTER AND NEAR-SURFACE ROOT BIOMASS HAD RECOVERED ENOUGH TO ADEQUATELY PROTECT THE SITE FROM ALL BUT EXTREME PRECIPITATION EVENTS.

Technical Abstract: EXPANSION OF WESTERN JUNIPER WOODLANDS IN THE SAGEBRUSH STEPPE CAN DRAMATICALLY CHANGE PLANT COMPOSITION, REDUCE UNDERSTORY VEGETATION PRODUCTION AND CONSEQUENTLY NEGATIVELY IMPACT THE HYDROLOGIC RESPONSE OF A SITE. CUTTING OF WESTERN JUNIPER CAN POTENTIALLY RESTORE THE UNDERSTORY VEGETATION AND IMPROVE A SITE¿S HYDROLOGIC CONDITION. LITTLE IS KNOWN ABOUT THE RATE OF HYDROLOGIC RECOVERY OR THE DEGREE OF UNDERSTORY NEEDED TO ADEQUATELY PROTECT A SITE FOLLOWING JUNIPER REMOVAL. THE OBJECTIVE OF THIS STUDY WAS TO QUANTIFY THE LONG-TERM IMPACT OF CUTTING WESTERN JUNIPER ON INFILTRATION, OVERLAND FLOW DYNAMICS, RILL AND INTERRILL EROSION RATES. LARGE-PLOT RAINFALL SIMULATION AND RILLING PROCEDURES WERE USED TO COMPARE INFILTRATION, RUNOFF AND EROSION RATES BETWEEN JUNIPER CUT AND UNCUT PLOTS TEN YEARS AFTER JUNIPER CUTTING. THE JUNIPER DOMINATED (UNCUT) PLOTS BEGAN TO RUNOFF AFTER RAINFALL WAS APPLIED EQUIVALENT TO A TWO-YEAR RETURN PERIOD THUNDERSTORM. JUNIPER CUT PLOTS DID NOT RUNOFF UNTIL THE EQUIVALENT OF A 100-YEAR RETURN PERIOD THUNDERSTORM WAS APPLIED. THE UNCUT PLOTS ALSO PRODUCED HIGH QUANTITIES OF INTERRILL AND RILL EROSION COMPARED TO NEAR ZERO LEVELS MEASURED ON THE PLOTS WHERE JUNIPER HAD BEEN REMOVED. TEN YEARS FOLLOWING JUNIPER CUTTING, JUNIPER INDUCED REDUCTIONS IN UNDERSTORY CANOPY COVER, GROUND COVER (LITTER, BASAL COVER, ETC.), SOIL ORGANIC MATTER AND NEAR-SURFACE ROOT BIOMASS HAD RECOVERED ENOUGH TO ADEQUATELY PROTECT THE SITE FROM ALL BUT EXTREME PRECIPITATION EVENTS.