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Brunello AT, Nardoto GB, Santos FLS, Sena-Souza JP, Quesada CAN, Lloyd JJ, Domingues TF. Soil δ 15N spatial distribution is primarily shaped by climatic patterns in the semiarid Caatinga, Northeast Brazil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 908:168405. [PMID: 37951261 DOI: 10.1016/j.scitotenv.2023.168405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 11/03/2023] [Accepted: 11/05/2023] [Indexed: 11/13/2023]
Abstract
Soil nitrogen isotopic composition (δ15Nsoil) is an invaluable tool as it integrates nitrogen (N) transformations in soils. In addition to serving as a baseline to understand the N cycle, spatial representations of δ15Nsoil across landscapes (or isoscapes) is a multi-purpose tool useful to investigate, for example, plant-microbe interactions, animal migration and forensics. We investigate the climatic and edaphic controls of δ15Nsoil utilising data from 29 geographical locations sampled across the semiarid Brazilian Caatinga biome. The sampling covered a mean annual precipitation (PA) gradient ranging from 0.51 to 1.36 m a-1 and eight soil types originating from three different geological origins. Our data show that the combination of higher aridity and lower seasonality (ψ) leads to higher values of δ15Nsoil. Moreover, soil total carbon had a positive relationship with δ15Nsoil, appearing within the best-supported models according to the information-theoretic approach undertaken here. The contribution to the plant communities by the Fabaceae trees expressed as their basal area was not related to δ15Nsoil values, suggesting that the magnitude of biological N fixation in the Caatinga is not large enough to be reflected in the soil. In addition, considering PA in a categorical fashion, i.e., 'high' (> 0.8 m a-1) and 'low' PA (< 0.8 m a-1), we found that, within the wetter category, δ15Nsoil was positively related to several soil properties (i.e., clay content, effective cation exchange capacity, exchangeable calcium, silt content, pHH2O, total phosphorus and sum of bases) and negatively related to sand content. Our study provides new insights into the functioning of semiarid ecosystems from a pedo-isotopic perspective and contributes to the overall understanding of the N cycle in the Caatinga region, with the potential to support the development of new conceptualisation of biogeochemical process and testing of global models that simulate N and C cycles.
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Affiliation(s)
- Alexandre T Brunello
- Universidade de São Paulo, FFCLRP, Departamento de Biologia, Av. dos Bandeirantes, 3900, Monte Alegre, Ribeirão Preto, SP, Brazil
| | - Gabriela B Nardoto
- Universidade de Brasília, Departamento de Ecologia, Campus Universitário Darcy Ribeiro, Asa Norte, Brasília, DF, Brazil
| | - Fábio Luís S Santos
- Universidade de Brasília, Departamento de Ecologia, Campus Universitário Darcy Ribeiro, Asa Norte, Brasília, DF, Brazil
| | - João Paulo Sena-Souza
- Universidade Estadual de Montes Claros (Unimontes), Departamento de Geociências, Campus Professor Darcy Ribeiro, Montes Claros, MG, Brazil
| | - Carlos A N Quesada
- Instituto Nacional de Pesquisas da Amazônia, Manaus Cx. Postal 2223 - CEP 69080-971, Amazonas, Brazil
| | - Jonathan J Lloyd
- School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia
| | - Tomas F Domingues
- Universidade de São Paulo, FFCLRP, Departamento de Biologia, Av. dos Bandeirantes, 3900, Monte Alegre, Ribeirão Preto, SP, Brazil.
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Feng M, Peng S, Wang Y, Ciais P, Goll DS, Chang J, Fang Y, Houlton BZ, Liu G, Sun Y, Xi Y. Overestimated nitrogen loss from denitrification for natural terrestrial ecosystems in CMIP6 Earth System Models. Nat Commun 2023; 14:3065. [PMID: 37244896 DOI: 10.1038/s41467-023-38803-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 05/12/2023] [Indexed: 05/29/2023] Open
Abstract
Denitrification and leaching nitrogen (N) losses are poorly constrained in Earth System Models (ESMs). Here, we produce a global map of natural soil 15N abundance and quantify soil denitrification N loss for global natural ecosystems using an isotope-benchmarking method. We show an overestimation of denitrification by almost two times in the 13 ESMs of the Sixth Phase Coupled Model Intercomparison Project (CMIP6, 73 ± 31 Tg N yr-1), compared with our estimate of 38 ± 11 Tg N yr-1, which is rooted in isotope mass balance. Moreover, we find a negative correlation between the sensitivity of plant production to rising carbon dioxide (CO2) concentration and denitrification in boreal regions, revealing that overestimated denitrification in ESMs would translate to an exaggeration of N limitation on the responses of plant growth to elevated CO2. Our study highlights the need of improving the representation of the denitrification in ESMs and better assessing the effects of terrestrial ecosystems on CO2 mitigation.
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Affiliation(s)
- Maoyuan Feng
- Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, and Laboratory for Earth Surface Processes, Peking University, Beijing, China
- Institute of Carbon Neutrality, Peking University, Beijing, China
| | - Shushi Peng
- Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, and Laboratory for Earth Surface Processes, Peking University, Beijing, China.
- Institute of Carbon Neutrality, Peking University, Beijing, China.
| | - Yilong Wang
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
| | - Philippe Ciais
- Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France
- The Cyprus Institute 20 Konstantinou Kavafi Street, 2121, Nicosia, Cyprus
| | - Daniel S Goll
- Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Jinfeng Chang
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | - Yunting Fang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
| | - Benjamin Z Houlton
- Department of Ecology and Evolutionary Biology and Department of Global Development, CALS, Cornell University, Ithaca, NY, USA
| | - Gang Liu
- Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, and Laboratory for Earth Surface Processes, Peking University, Beijing, China
- Institute of Carbon Neutrality, Peking University, Beijing, China
| | - Yan Sun
- College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Yi Xi
- Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, and Laboratory for Earth Surface Processes, Peking University, Beijing, China
- Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France
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Global distribution and climate sensitivity of the tropical montane forest nitrogen cycle. Nat Commun 2022; 13:7364. [PMID: 36450741 PMCID: PMC9712492 DOI: 10.1038/s41467-022-35170-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 11/18/2022] [Indexed: 12/02/2022] Open
Abstract
Tropical forests are pivotal to global climate and biogeochemical cycles, yet the geographic distribution of nutrient limitation to plants and microbes across the biome is unresolved. One long-standing generalization is that tropical montane forests are nitrogen (N)-limited whereas lowland forests tend to be N-rich. However, empirical tests of this hypothesis have yielded equivocal results. Here we evaluate the topographic signature of the ecosystem-level tropical N cycle by examining climatic and geophysical controls of surface soil N content and stable isotopes (δ15N) from elevational gradients distributed across tropical mountains globally. We document steep increases in soil N concentration and declining δ15N with increasing elevation, consistent with decreased microbial N processing and lower gaseous N losses. Temperature explained much of the change in N, with an apparent temperature sensitivity (Q10) of ~1.9. Although montane forests make up 11% of forested tropical land area, we estimate they account for >17% of the global tropical forest soil N pool. Our findings support the existence of widespread microbial N limitation across tropical montane forest ecosystems and high sensitivity to climate warming.
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