caa a22 4500 477112102 CHVBK 20180405111612.0 cr unu---uuuuu 170330e19960501xx s 000 0 eng 10.1007/BF00029056 doi (NATIONALLICENCE)springer-10.1007/BF00029056 15N natural abundance in forest and pasture soils of the Brazilian Amazon Basin [Elektronische Daten] [Marisa Piccolo, Christopher Neill, Jerry Melillo, Carlos Cerri, Paul Steudler] The natural abundance of 15N was examined in soil profiles from forests and pastures of the Brazilian Amazon Basin to compare tropical forests on a variety of soil types and to investigate changes in the sources of nitrogen to soils following deforestation for cattle ranching. Six sites in the state of Rondônia, two sites in Pará and one in Amazonas were studied. All sites except one were chronosequences and contained native forest and one or more pastures ranging from 2 to 27 years old. Forest soil δ15N values to a depth of 1 m ranged from 8‰ to 23‰ and were higher than values typically found in temperate forests. A general pattern of increasing δ15N values with depth near the soil surface was broadly similar to patterns in other forests but a decrease in δ15N values in many forest profiles between 20 and 40 cm suggests that illuviation of 15N-depleted nitrate may influence total soil δ15N values in deeper soil where total N concentrations are low. In four chronosequences in Rondônia, the δ15N values of surface soil from pastures were lower than in the original forest and δ15N values were increasingly depleted in older pastures. Inputs of atmospheric N by dinitrogen fixation could be an important N source in these pastures. Other pastures in Amazonas and Pará and Rondônia showed no consistent change from forest values. The extent of fractionation that leads to 15N enrichment in soils was broadly similar over a wide range of soil textures and indicated that similar processes control N fractionation and loss under tropical forest over a broad geographic region. Forest δ15N profiles were consistent with conceptual models that explain enrichment of soil δ15N values by selective loss of 14N during nitrification and denitrification. Kluwer Academic Publishers, 1996 nitrogen nationallicence nitrogen fixation nationallicence stable isotopes nationallicence tropical forest nationallicence tropical pasture nationallicence Piccolo Marisa Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Avenida Centenário 303, Caixa Postal 96, CEP 13 416 000, Piracicaba, SP, Brazil aut Neill Christopher Marine Biological Laboratory, The Ecosystems Center, 02543, Woods Hole, MA, USA aut Melillo Jerry Marine Biological Laboratory, The Ecosystems Center, 02543, Woods Hole, MA, USA aut Cerri Carlos Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Avenida Centenário 303, Caixa Postal 96, CEP 13 416 000, Piracicaba, SP, Brazil aut Steudler Paul Marine Biological Laboratory, The Ecosystems Center, 02543, Woods Hole, MA, USA aut Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl 182/2(1996-05-01), 249-258 0032-079X 182:2<249 1996 182 11104 https://doi.org/10.1007/BF00029056 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00029056 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Piccolo Marisa Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Avenida Centenário 303, Caixa Postal 96, CEP 13 416 000, Piracicaba, SP, Brazil aut NATIONALLICENCE 700 1- Neill Christopher Marine Biological Laboratory, The Ecosystems Center, 02543, Woods Hole, MA, USA aut NATIONALLICENCE 700 1- Melillo Jerry Marine Biological Laboratory, The Ecosystems Center, 02543, Woods Hole, MA, USA aut NATIONALLICENCE 700 1- Cerri Carlos Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Avenida Centenário 303, Caixa Postal 96, CEP 13 416 000, Piracicaba, SP, Brazil aut NATIONALLICENCE 700 1- Steudler Paul Marine Biological Laboratory, The Ecosystems Center, 02543, Woods Hole, MA, USA aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl/ 182/2(1996-05-01), 249-258 0032-079X 182:2<249 1996 182 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer