title: The effects of throughfall manipulation on soil leaching in a deciduous forest.
abstract: The effects of changing precipitation on soil leaching in a deciduous forest were examined by experimentally manipulating throughfall fluxes in the field. In addition to an ambient treatment (AMB), throughfall fluxes were reduced by 33% (DRY treatment) and increased by 33% (WET treatment) using a system of rain gutters and sprinklers on Walker Branch Watershed, Tennessee. Soil leaching was measured with resin lysimeters in the O horizons and with ceramic cup lysimeters in the E (25 cm) and Bt (70 cm) horizons. Large and statistically significant treatment effects on N fluxes were found in the O horizons (lower N fluxes in the DRY and higher N fluxes in the WET treatment). Together with the greater O horizon N content observed in the DRY treatment, this suggested that N was being immobilized at a greater rate in the DRY treatment than in the AMB or WET treatments. No statistically significant treatment effects on soil solution were found in the E horizons with the exception of (Ca2+ + Mg2+) to K+ ratio. Statistically significant treatment effects on electrical conductivity (EC), pH, Ca2+, Mg2+, K+, Na+, SO4(2-), and Cl- were found in the Bt horizons due to differences between the DRY and other treatments. Despite this, calculated fluxes of Ca2+, Mg2+, K+, Na+, SO4(2-), and Cl- were lowest in the DRY treatment. These results suggest that lower precipitation will cause temporary N immobilization in litter and long-term enrichment in soil base cations whereas increased precipitation will cause long-term depletion of soil base cations.
authors.affiliation: Environmental and Resource Sciences, Univ. of Nevada, Reno 89557, USA. dwj@unr.edu
authors.forename: D W
authors.initials: DW
authors.lastname: Johnson
authors.forename: P J
authors.initials: PJ
authors.lastname: Hanson
authors.forename: D E
authors.initials: DE
authors.lastname: Todd
mesh_terms: D002412:Cations; D004784:Environmental Monitoring; D009584:Nitrogen / Q000032:analysis*; D018515:Plant Leaves / Q000737:chemistry; D011891:Rain; D012989:Soil Pollutants / Q000032:analysis*; D014197:Trees; D014872:Water Movements
chemical_list: D002412:Cations; D012989:Soil Pollutants; D009584:Nitrogen