caa a22 4500 467885834 CHVBK 20180406152734.0 cr unu---uuuuu 170328e20061201xx s 000 0 eng 10.1007/s10021-006-0177-z doi (NATIONALLICENCE)springer-10.1007/s10021-006-0177-z Calcium Additions and Microbial Nitrogen Cycle Processes in a Northern Hardwood Forest [Elektronische Daten] [Peter Groffman, Melany Fisk, Charles Driscoll, Gene Likens, Timothy Fahey, Christopher Eagar, Linda Pardo] Evaluating, and possibly ameliorating, the effects of base cation depletion in forest soils caused by acid deposition is an important topic in the northeastern United States. We added 850 kg Ca ha−1 as wollastonite (CaSiO3) to an 11.8-ha watershed at the Hubbard Brook Experimental Forest (HBEF), a northern hardwood forest in New Hampshire, USA, in fall 1999 to replace calcium (Ca) leached from the ecosystem by acid deposition over the past 6 decades. Soil microbial biomass carbon (C) and nitrogen (N) concentrations, gross and potential net N mineralization and nitrification rates, soil solution and stream chemistry, soil:atmosphere trace gas (CO2, N2O, CH4) fluxes, and foliar N concentrations have been monitored in the treated watershed and in reference areas at the HBEF before and since the Ca addition. We expected that rates of microbial C and N cycle processes would increase in response to the treatment. By 2000, soil pH was increased by a full unit in the Oie soil horizon, and by 2002 it was increased by nearly 0.5 units in the Oa soil horizon. However, there were declines in the N content of the microbial biomass, potential net and gross N mineralization rates, and soil inorganic N pools in the Oie horizon of the treated watershed. Stream, soil solution, and foliar concentrations of N showed no response to treatment. The lack of stimulation of N cycling by Ca addition suggests that microbes may not be stimulated by increased pH and Ca levels in the naturally acidic soils at the HBEF, or that other factors (for example, phosphorus, or Ca binding of labile organic matter) may constrain the capacity of microbes to respond to increased pH in the treated watershed. Possible fates for the approximately 10 kg N ha−1 decline in microbial and soil inorganic pools include components of the plant community that we did not measure (for example, seedlings, understory shrubs), increased fluxes of N2 and/or N storage in soil organic matter. These results raise questions about the factors regulating microbial biomass and activity in northern hardwood forests that should be considered in the context of proposals to mitigate the depletion of nutrient cations in soil. Springer Science+Business Media, Inc., 2007 acid deposition nationallicence calcium nationallicence carbon nationallicence Hubbard Brook nationallicence microbial biomass nationallicence nitrification nationallicence nitrogen nationallicence phosphorus nationallicence Groffman Peter Institute of Ecosystem Studies, Box AB, 12545, Millbrook, New York, USA aut Fisk Melany Department of Biology, Appalachian State University, 28608, Boone, North Carolina, USA aut Driscoll Charles Department of Civil and Environmental Engineering, Syracuse University, 13244, Syracuse, New York, USA aut Likens Gene Institute of Ecosystem Studies, Box AB, 12545, Millbrook, New York, USA aut Fahey Timothy Department of Natural Resources, Cornell University, 14853, Ithaca, New York, USA aut Eagar Christopher Northeastern Research Station, USDA Forest Service, PO Box 640, 03824, Durham, New Hampshire, USA aut Pardo Linda Northeastern Research Station, USDA Forest Service, PO Box 968, 05402, Burlington, Vermont, USA aut Ecosystems Springer-Verlag; www.springer-ny.com 9/8(2006-12-01), 1289-1305 1432-9840 9:8<1289 2006 9 10021 https://doi.org/10.1007/s10021-006-0177-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10021-006-0177-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Groffman Peter Institute of Ecosystem Studies, Box AB, 12545, Millbrook, New York, USA aut NATIONALLICENCE 700 1- Fisk Melany Department of Biology, Appalachian State University, 28608, Boone, North Carolina, USA aut NATIONALLICENCE 700 1- Driscoll Charles Department of Civil and Environmental Engineering, Syracuse University, 13244, Syracuse, New York, USA aut NATIONALLICENCE 700 1- Likens Gene Institute of Ecosystem Studies, Box AB, 12545, Millbrook, New York, USA aut NATIONALLICENCE 700 1- Fahey Timothy Department of Natural Resources, Cornell University, 14853, Ithaca, New York, USA aut NATIONALLICENCE 700 1- Eagar Christopher Northeastern Research Station, USDA Forest Service, PO Box 640, 03824, Durham, New Hampshire, USA aut NATIONALLICENCE 700 1- Pardo Linda Northeastern Research Station, USDA Forest Service, PO Box 968, 05402, Burlington, Vermont, USA aut NATIONALLICENCE 773 0- Ecosystems Springer-Verlag; www.springer-ny.com 9/8(2006-12-01), 1289-1305 1432-9840 9:8<1289 2006 9 10021 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer