Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: AGRICULTURAL LAND MANAGEMENT TO OPTIMIZE PRODUCTIVITY AND NATURAL RESOURCE CONSERVATION AT FARM AND WATERSHED SCALES

Location: Great Plains Agroclimate and Natural Resources Research Unit

Title: Measurements of Canopy Interception and Trasnpiration of Openly-Grown Eastern Redcedar in Central Oklahoma

Authors
item STARKS, PATRICK
item Venuto, Bradley -
item Dugas, William -
item KINIRY, JAMES

Submitted to: Environment and Natural Resources Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 8, 2014
Publication Date: June 10, 2014
Citation: Starks, P.J., Venuto, B.C., Dugas, W.A., Kiniry, J.R. 2014. Measurements of Canopy Interception and Trasnpiration of Openly-Grown Eastern Redcedar in Central Oklahoma. Environment and Natural Resources Research. Available online: http://www.ccsenet.org/journal/index.php/enrr/issue/view/1077.

Interpretive Summary: In recent decades Eastern redcedar has been rapidly encroaching and degrading native prairie and rangeland landscapes in the Great Plains of the U.S. Increase in redcedar density and areal coverage may negatively impact local and regional water budgets through increased transpiration and canopy interception of precipitation, and it is the semi-arid and transitional zones between semi-arid and humid regions where impacts of redcedar encroachment are likely to be felt most strongly. Two study sites were located in central Oklahoma (a transitional zone between semi-arid and humid climates) to measure transpiration and canopy interception. Two trees at each site were instrumented from October 2009 through mid-July of 2012 to quantify redcedar canopy interception. Two limbs (one on the north face and one on the south face) on two separate trees at Site 1 were instrumented with sapflux sensors from August 2010 through mid-July 2012. Limb level transpiratin was scaled to tree level using ratios of limb leaf area to tree leaf area, and limb cross-sectional area to bole cross-sectional area. Leaf areas were determined from data collected from Ashe Juniper and redcedar. Whole tree transpiration was measured on two small redcedar trees at Site 2 from mid-May 2011 through mid-July 2012. Redcedar canopies were found to intercept all precipitation is less than 2.4 mm. For central Oklahoma, redcedar canopies reduce annual precipitation received at the surface by about 33%, and as much as 39% in the western portion of the state. Transpiration of shallow rooted redcedars was found to respond quickly to precipitation events while the deeper rooted redcedars did not. Deeply rooted redcedars exhibited higher T rates than native grasses while shallow rooted redcedars transpired at rates closely matching the native grasses. Significant canopy interception of precipitation, coupled with T rates as large as or larger than native grasses, and year-round T, suggest that increases in redcedar density and areal coverage could have a negative impact on local water resources. Redcedars decrease the amount of rainfall reaching the soil, thus reducing infiltration and runoff. Year-round T continuously taps soil water reserves, thereby negatively impacting ground water recharge rates.

Technical Abstract: In recent decades Eastern redcedar (Juniperus virginiana L.) has been rapidly encroaching and degrading native prairie and rangeland landscapes in the Great Plains of the U.S. Increase in redcedar density and areal coverage may negatively impact local and regional water budgets through increased transpiration (T) and canopy interception (CI) of precipitation, and it is the semi-arid and transitional zones between semi-arid and humid regions where impacts of redcedar encroachment are likely to be felt most strongly. Two study sites were located in central Oklahoma (a transitional zone between semi-arid and humid climates) to measure T and CI. Two trees at each site were instrumented from October 2009 through mid-July of 2012 to quantify redcedar CI. Two limbs (one on the north face and one on the south face) on two separate trees at Site 1 were instrumented with sapflux sensors from August 2010 through mid-July 2012. Limb level T was scaled to tree level T using ratios of limb leaf area to tree leaf area, and limb cross-sectional area to bole cross-sectional area. Leaf areas were determined from data collected from Ashe Juniper (J. asheii) and redcedar. Whole tree T was measured on two small redcedar trees at Site 2 from mid-May 2011 through mid-July 2012. Redcedar canopies were found to intercept all precipitation is less than 2.4 mm. For central Oklahoma, redcedar canopies reduce annual precipitation received at the surface by about 33%, and as much as 39% in the western portion of the state. Transpiration of shallow rooted redcedars was found to respond quickly to precipitation events while the deeper rooted redcedars did not. Deeply rooted redcedars exhibited higher T rates than native grasses while shallow rooted redcedars transpired at rates closely matching the native grasses. Significant canopy interception of precipitation, coupled with T rates as large as or larger than native grasses, and year-round T, suggest that increases in redcedar density and areal coverage could have a negative impact on local water resources. Redcedars decrease the amount of rainfall reaching the soil, thus reducing infiltration and runoff. Year-round T continuously taps soil water reserves, thereby negatively impacting ground water recharge rates.

Last Modified: 9/10/2014
Footer Content Back to Top of Page