Interception
When precipitation (rain or snow) occurs, it either goes straight to the leaf litter or soil or is intercepted by the canopy. Precipitation intercepted by the canopy either falls to the leaf litter or soil or evaporates. Finally precipitation in the leaf litter either infiltrates to the soil profile or is lost to evaporation. A large portion of intercepted precipitation is evaporated to the atmosphere and therefore does not enter the soil profile (Calder 1998). Precipitation interception by either the tree canopy or the leaf litter is a major component of the land surface water cycle, consisting of as much as half of the precipitation in some systems (Hörmann et al. 1996; Carlyle-Moses 2004). Interception can range from 11 – 36% in deciduous forests and 9 – 48% in conifer forests (Hörmann et al. 1996). Semi-arid systems are water limited, and even small changes to the hydrologic cycle from increased interception can cause drastic changes to the system.
Diagram of interception and throughfall
Canopy interception loss in rangelands can range from 1% to 80% of the annual water budget, but is typically between 20% to 40% (Wilcox et al. 2003). Piñon and juniper plant-level interception ranges from 14% to 71% (Collings 1966; Young et al. 1984; Eddleman and Miller 1991; Larsen 1993; Taucer 2006; Owens et al. 2006). In our study at RCEW, interception for the 34 events smaller than 5 mm was 84.0% and 48.7% for the 18 events larger than 5 mm.
Information on this page is based on this publication, where you can find more detailed review of interception in juniper and pinyon species and more detailed information about this study.
Citations
Calder, I. R. 1998. Water use by forests, limits and controls. Tree Physiology 18:625–631.
Carlyle-Moses, D. . 2004. Throughfall, stemflow, and canopy interception loss fluxes in a semi-arid Sierra Madre Oriental matorral community. Journal of Arid Environments 58:181–202.
Collings, M. R. 1966. Throughfall for summer thunderstorms in a juniper and pinyon woodland, Cibecue Ridge, Arizona. Page 13. U.S. Geological Survey.
Eddleman, L. E., and P. M. Miller. 1991. Potential impacts of western juniper on the hydrologic cycle. Pages 29–31 Proceedings, symposium in ecology and management of riparian shrub communities.
Hörmann, G., A. Branding, T. Clemen, M. Herbst, A. Hinrichs, and F. Thamm. 1996. Calculation and simulation of wind controlled canopy interception of a beech forest in Northern Germany. Agricultural and Forest Meteorology 79:131–148.
Larsen, R. E. 1993. Interception and water holding capacity of western juniper. Oregon State University.
Owens, M. K., R. K. Lyons, and C. L. Alejandro. 2006. Rainfall partitioning within semiarid juniper communities: effects of event size and canopy cover. Hydrological Processes 20:3179–3189.
Taucer, P. I. 2006. The effects of juniper removal on rainfall partitioning in the Edwards Aquifer region: large-scale rainfall simulation experiments. Texas A&M University.
Wilcox, B. P., D. D. Breshears, and M. S. Seyfried. 2003. Rangelands, water balance on. Pages 791–794 in B. A. Stewart and T. A. Howell, editors. Encyclopedia of Water Science. New York, NY, USA.
Young, J. A., R. A. Evans, and D. A. Easi. 1984. Stem flow on western juniper (Juniperus occidentalis) trees. Weed Science 32:320–327.
