Stable isotope signatures of soil nitrogen on an environmental–geomorphic gradient within the Congo Basin
<p>Nitrogen (N) availability can be highly variable in tropical forests on regional and local scales. While environmental gradients influence N cycling on a regional scale, topography is known to affect N availability on a local scale. We compared natural abundance of <span class="inli...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2021-03-01
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| Series: | SOIL |
| Online Access: | https://soil.copernicus.org/articles/7/83/2021/soil-7-83-2021.pdf |
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| author | S. Baumgartner S. Baumgartner M. Bauters M. Bauters M. Barthel T. W. Drake L. C. Ntaboba B. M. Bazirake J. Six P. Boeckx K. Van Oost |
| author_facet | S. Baumgartner S. Baumgartner M. Bauters M. Bauters M. Barthel T. W. Drake L. C. Ntaboba B. M. Bazirake J. Six P. Boeckx K. Van Oost |
| author_sort | S. Baumgartner |
| collection | DOAJ |
| description | <p>Nitrogen (N) availability can be highly variable in tropical forests on regional and local scales. While environmental gradients influence N cycling
on a regional scale, topography is known to affect N availability on a local scale. We compared natural abundance of <span class="inline-formula"><sup>15</sup>N</span> isotopes of soil
profiles in tropical lowland forest, tropical montane forest, and subtropical Miombo woodland within the Congo Basin as a proxy to assess
ecosystem-level differences in N cycling. Soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> profiles indicated that N cycling in the montane forest is relatively more
closed and dominated by organic N turnover, whereas the lowland forest and Miombo woodland experienced a more open N cycle dominated by
inorganic N. Furthermore, we examined the effect of slope gradient on soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> within forest types to quantify local differences
induced by topography. Our results show that slope gradient only affects the soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> in the Miombo forest, which is prone to
erosion due to a lower vegetation cover and intense rainfall at the onset of the wet season. Lowland forest, on the other hand, with a flat
topography and protective vegetation cover, showed no influence of topography on soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> in our study site. Despite the steep
topography, slope angles do not affect soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> in the montane forest, although stable isotope signatures exhibited higher
variability within this ecosystem. A pan-tropical analysis of soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> values (i.e., from our study and literature) reveals that
soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> in tropical forests is best explained by factors controlling erosion, namely mean annual precipitation, leaf area index,
and slope gradient. Erosive forces vary immensely between different tropical forest ecosystems, and our results highlight the need for more spatial
coverage of N cycling studies in tropical forests, to further elucidate the local impact of topography on N cycling in this biome.</p> |
| first_indexed | 2024-12-22T21:00:18Z |
| format | Article |
| id | doaj.art-0681f98910bd4e2288ef78ef8b0cbc8c |
| institution | Directory Open Access Journal |
| issn | 2199-3971 2199-398X |
| language | English |
| last_indexed | 2024-12-22T21:00:18Z |
| publishDate | 2021-03-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | SOIL |
| spelling | doaj.art-0681f98910bd4e2288ef78ef8b0cbc8c2022-12-21T18:12:51ZengCopernicus PublicationsSOIL2199-39712199-398X2021-03-017839410.5194/soil-7-83-2021Stable isotope signatures of soil nitrogen on an environmental–geomorphic gradient within the Congo BasinS. Baumgartner0S. Baumgartner1M. Bauters2M. Bauters3M. Barthel4T. W. Drake5L. C. Ntaboba6B. M. Bazirake7J. Six8P. Boeckx9K. Van Oost10Earth and Life Institute, UCLouvain, Louvain-la-Neuve, 1348, BelgiumDepartment of Green Chemistry and Technology, Ghent University, Ghent, 9000, BelgiumDepartment of Green Chemistry and Technology, Ghent University, Ghent, 9000, BelgiumDepartment of Environment, Ghent University, Ghent, 9000, BelgiumDepartment of Environmental Systems Science, Swiss Federal Institute of Technology, ETH Zurich, Zurich, 8092, SwitzerlandDepartment of Environmental Systems Science, Swiss Federal Institute of Technology, ETH Zurich, Zurich, 8092, SwitzerlandDépartment d'Agronomie, Université Catholique de Bukavu, Bukavu, DR CongoDepartment of General Agricultural Sciences, University of Lubumbashi, Lubumbashi, DR CongoDepartment of Environmental Systems Science, Swiss Federal Institute of Technology, ETH Zurich, Zurich, 8092, SwitzerlandDepartment of Green Chemistry and Technology, Ghent University, Ghent, 9000, BelgiumEarth and Life Institute, UCLouvain, Louvain-la-Neuve, 1348, Belgium<p>Nitrogen (N) availability can be highly variable in tropical forests on regional and local scales. While environmental gradients influence N cycling on a regional scale, topography is known to affect N availability on a local scale. We compared natural abundance of <span class="inline-formula"><sup>15</sup>N</span> isotopes of soil profiles in tropical lowland forest, tropical montane forest, and subtropical Miombo woodland within the Congo Basin as a proxy to assess ecosystem-level differences in N cycling. Soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> profiles indicated that N cycling in the montane forest is relatively more closed and dominated by organic N turnover, whereas the lowland forest and Miombo woodland experienced a more open N cycle dominated by inorganic N. Furthermore, we examined the effect of slope gradient on soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> within forest types to quantify local differences induced by topography. Our results show that slope gradient only affects the soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> in the Miombo forest, which is prone to erosion due to a lower vegetation cover and intense rainfall at the onset of the wet season. Lowland forest, on the other hand, with a flat topography and protective vegetation cover, showed no influence of topography on soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> in our study site. Despite the steep topography, slope angles do not affect soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> in the montane forest, although stable isotope signatures exhibited higher variability within this ecosystem. A pan-tropical analysis of soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> values (i.e., from our study and literature) reveals that soil <span class="inline-formula"><i>δ</i></span><span class="inline-formula"><sup>15</sup>N</span> in tropical forests is best explained by factors controlling erosion, namely mean annual precipitation, leaf area index, and slope gradient. Erosive forces vary immensely between different tropical forest ecosystems, and our results highlight the need for more spatial coverage of N cycling studies in tropical forests, to further elucidate the local impact of topography on N cycling in this biome.</p>https://soil.copernicus.org/articles/7/83/2021/soil-7-83-2021.pdf |
| spellingShingle | S. Baumgartner S. Baumgartner M. Bauters M. Bauters M. Barthel T. W. Drake L. C. Ntaboba B. M. Bazirake J. Six P. Boeckx K. Van Oost Stable isotope signatures of soil nitrogen on an environmental–geomorphic gradient within the Congo Basin SOIL |
| title | Stable isotope signatures of soil nitrogen on an environmental–geomorphic gradient within the Congo Basin |
| title_full | Stable isotope signatures of soil nitrogen on an environmental–geomorphic gradient within the Congo Basin |
| title_fullStr | Stable isotope signatures of soil nitrogen on an environmental–geomorphic gradient within the Congo Basin |
| title_full_unstemmed | Stable isotope signatures of soil nitrogen on an environmental–geomorphic gradient within the Congo Basin |
| title_short | Stable isotope signatures of soil nitrogen on an environmental–geomorphic gradient within the Congo Basin |
| title_sort | stable isotope signatures of soil nitrogen on an environmental geomorphic gradient within the congo basin |
| url | https://soil.copernicus.org/articles/7/83/2021/soil-7-83-2021.pdf |
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