@Article{Schimann_etal2008,
author="Schimann, H.
and Ponton, S.
and Hattenschwiler, S.
and Ferry, B.
and Lensi, R.
and Domenach, A.M.
and Roggy, J.C.",
title="Differing nitrogen use strategies of two tropical rainforest late successional tree species in French Guiana: Evidence from N-15 natural abundance and microbial activities",
journal="Soil Biology \& Biochemistry",
year="2008",
publisher="PERGAMON-ELSEVIER SCIENCE LTD",
volume="40",
number="2",
pages="487--494",
optkeywords="soil",
optkeywords="litter",
optkeywords="nitrate",
optkeywords="nitrification",
optkeywords="tree rooting",
optkeywords="N-15",
optkeywords="Eperua falcata",
optkeywords="Dicorynia guianensis",
optkeywords="tropical forest",
abstract="Previous studies in lowland tropical rainforests of French Guiana showed that, among non-N-2-fixing trees, two groups of late successional species contrasting in their leaf N-15 natural abundance coexist, suggesting two different main ways of nitrogen acquisition. Two abundant late-successional species typically co-occurring in rainforests in French Guiana, namely Eperua falcata and Dicorynia guianensis, were chosen as representative of each group. Stable isotope techniques and measurements of potentials of microbial N transformation were performed to assess to what extent leaf N-15 natural abundance of these species could be related to (i) delta N-15 signatures of soil mineral N sources and (ii) the capacity of soil to express nitrification and denitrification (both processes being directly involved in the balance between NH4+ and NO3-). Soil delta N-15-NH4+ was roughly similar to leaf delta N-15 of D. guianensis (around 3.5 parts per thousand), suggesting a preferential use of NH4+, whereas in E. falcata, leaf delta N-15 values were closer to root delta N-15-NO3- values (0.2 and -2.0 parts per thousand, respectively), suggesting a preferential use of NO3-. These differences in N source utilization were not accompanied by differences in availability in soil NO3- or in intensity of microbial functions responsible for soil N mineral evolution. However, (i) under both tree species, these functions showed clear spatial partitioning, with denitrification occurring potentially in soil and nitrification in the litter layer, and (ii) E falcata fine roots colonized the litter layer much more strongly than D. guianensis fine roots. This strongly suggests that (i) the contrasted leaf delta N-15 values found in the two late-successional species reveal distinct N acquisition strategies and (ii) the ability of roots to predominantly exploit the litter layer (E falcata) or the soil (D. guianensis) may constitute an important explanation of the observed differences. A complementarity between tree species, based on mineral N resource partitioning (itself resulting from a spatially structured location of the microbial functions responsible for the balance between NH4+ and NO3-), n thus be supposed. (c) 2007 Elsevier Ltd. All rights reserved.",
optnote="ISI:000251655800021",
optnote="exported from refbase (http://php.ecofog.gf/refbase/show.php?record=146), last updated on Wed, 04 May 2011 14:21:54 -0300",
issn="0038-0717"
}