title: Forest liming increases forest floor carbon and nitrogen stocks in a mixed hardwood forest.
abstract: In acid-impacted forests, decreased soil pH and calcium (Ca) availability have the potential to influence biotic and abiotic controls on carbon (C) and nitrogen (N) cycling. We investigated the effects of liming on above- and belowground C and N pools and fluxes 19 years after lime addition to the Woods Lake Watershed, Adirondack Park, New York, USA. Soil pH and exchangeable Ca remained elevated in the forest floor and upper mineral soil of limed areas. Forest floor C and N stocks were significantly larger in limed plots (68 vs. 31 Mg C/ha, and 3.0 vs. 1.5 Mg N/ha), resulting from a larger mass of Oa material. Liming reduced soil basal respiration rates by 17% and 43% in the Oe and Oa horizons, respectively. Net N mineralization was significantly lower in the limed soils for both forest floor horizons. Additional measurements of forest floor depth outside of our study plots, but within the treatment and control subcatchments also showed a deeper forest floor in limed areas; however, the mean depth of limed forest floor was 5 cm shallower than that observed in our study plots. Using a differential equation model of forest floor C dynamics, we found that liming effects on C fluxes measured within our study plots could explain the small observed increase in the Oe C stock but were not large enough to explain the increase in the Oa. Our catchment-wide assessment of forest floor depth, however, indicates that our plot analysis may be an overestimate of ecosystem-scale C and N stocks. Our results suggest that the mechanisms identified in our study, primarily liming-induced reduction in decomposition rates, may account for much of the observed increase in forest floor C. These findings emphasize the importance of understanding of the effects of liming in hardwood forests, and the long-term impacts of acid deposition on forest C and N uptake and retention.
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York 14853, USA. april.melvin@ufl.edu
authors.forename: April M
authors.initials: AM
authors.lastname: Melvin
authors.affiliation: Department of Biology, University of Florida, Gainesville, Florida 32611, USA.
authors.forename: Jeremy W
authors.initials: JW
authors.lastname: Lichstein
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Christine L
authors.initials: CL
authors.lastname: Goodale
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D003247:Conservation of Natural Resources; D017753:Ecosystem; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological; D009518:New York; D009584:Nitrogen / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D014197:Trees
chemical_list: D017610:Calcium Compounds; D010087:Oxides; D012987:Soil; D002244:Carbon; C016538:lime; D009584:Nitrogen