In situ gross nitrogen transformations differ between temperate deciduous and coniferous forest soils
- 718 Downloads
Despite long-term enhanced nitrogen (N) inputs, forests can retain considerable amounts of N. While rates of N inputs via throughfall and N leaching are increased in coniferous stands relative to deciduous stands at comparable sites, N leaching below coniferous stands is disproportionally enhanced relative to the N input. A better understanding of factors affecting N retention is needed to assess the impact of changing N deposition on N cycling and N loss of forests. Therefore, gross N transformation pathways were quantified in undisturbed well-drained sandy soils of adjacent equal-aged deciduous (pedunculate oak (Quercus robur L.)) and coniferous (Scots pine (Pinus sylvestris L.)) planted forest stands located in a region with high N deposition (north Belgium). In situ inorganic 15N labelling of the mineral topsoil (0–10 cm) combined with numerical data analysis demonstrated that (i) all gross N transformations differed significantly (p < 0.05) between the two forest soils, (ii) gross N mineralization in the pine soil was less than half the rate in the oak soil, (iii) meaningful N immobilization was only observed for ammonium, (iv) nitrate production via oxidation of organic N occurred three times faster in the pine soil while ammonium oxidation was similar in both soils, and (v) dissimilatory nitrate reduction to ammonium was detected in both soils but was higher in the oak soil. We conclude that the higher gross nitrification (including oxidation of organic N) in the pine soil compared to the oak soil, combined with negligible nitrate immobilization, is in line with the observed higher nitrate leaching under the pine forest.
KeywordsForest type Mineralization Nitrification 15N Nutrient cycling Tracing model
We thank Evy Ampoorter, Lander Baeten, Dries Roobroeck, Margot Vanhellemont, and Luc Willems for their help with the nitrogen additions and soil processing, and Eric Gillis, Katja Van Nieuland, and Jan Vermeulen for assisting in the laboratory work. Mme Goossens and Natuurpunt vzw are acknowledged for the kind permission to use their forest stands for this research project. We would like to thank the associate editor and two anonymous reviewers for their valuable comments on the manuscript. The first, third and fourth author were funded as postdoctoral fellow of the Research Foundation-Flanders (FWO) and the second author is supported by NitroEurope IP under the EC 6th Framework Programme (Contract No. 017841).
- Burnham KP, Anderson DR (2002) Model selection and inference: a practical information-theoretic approach, 2nd edn. Springer-Verlag, New YorkGoogle Scholar
- De Schrijver A, Geudens G, Wuyts K, Staelens J, Gielis L, Verheyen K (2009) Nutrient cycling in two continuous cover scenarios for forest conversion of pine plantations on sandy soil. I. Nutrient cycling via aboveground tree biomass. Can J For Res 39:441–452. doi: 10.1139/X08-176(IF:1.246) CrossRefGoogle Scholar
- Hart SC, Stark JM, Davidson EA, Firestone MK (1994) Nitrogen mineralization, immobilization, and nitrification. In: Weaver RW, Angle S, Bottomley P, Bezdicek D, Smith S, Tabatabi A, Wollum A (eds) Methods of soil analysis. Part 2. Microbiological and biochemical properties. Soil Science Society of America, Madison, WI, pp 985–1018Google Scholar
- Hauck RD (1982) Nitrogen isotope ratio analysis. In: Page AL, Miller RA, Keeney DR (eds) Methods of soil analysis. American Society of Agronomy, Madison, pp 735–779Google Scholar
- Jabiol B, Brêthes A, Ponge J-F, Toutain F, Brun J-J (1995) L’humus sous toutes ses formes. Ecole nationele du génie rural, des eaux et des forêts, Nancy, p 64Google Scholar
- Mulvaney RL (1996) Nitrogen-inorganic forms. In: Sparks DL (ed) Methods of soil analysis. American Society of Agronomy, Madison, pp 1123–1184Google Scholar
- Pedersen H, Dunkin KA, Firestone MK (1999) The relative importance of autotrophic and heterotrophic nitrification in a conifer forest soil as measured by 15N tracer and pool dilution techniques. Biogeochemistry 44:135–150Google Scholar
- Reich PB, Oleksyn J, Modrzynski J, Mrozinski P, Hobbie SE, Eissenstat DM, Chorover J, Chadwick OA, Hale CM, Tjoelker GM (2005) Linking litter calcium, earthworms and soil properties: a common garden test with 14 tree species. Ecol Lett 8:811–818. doi: 10.1111/j.1461-0248.2005.00779.x CrossRefGoogle Scholar
- Rütting T, Huygens D, Staelens J, Müller C, Boeckx P (2011) Advances in 15N tracing experiments: new labelling and data analysis approaches. Biochem Soc Trans 39:279–283Google Scholar
- Spiecker H, Hansen J, Hasenauer H, Klimo E, Skovsgaard JP, Sterba H, von Teuffel K (eds) (2004) Norway spruce conversion—options and consequences. Research report 18. European Forest Institute, BostonGoogle Scholar
- Yan E-R, Wang X-H, Huang J-J, Li G-Y, Zhou W (2008) Decline of soil nitrogen mineralization and nitrification during forest conversion of evergreen broad-leaved forest to plantations in the subtropical area of Eastern China. Biogeochemistry 89:239–251. doi: 10.1007/s10533-008-9216-5 CrossRefGoogle Scholar