Namib Desert primary productivity is driven by cryptic microbial community N-fixation
Abstract Carbon exchange in drylands is typically low, but during significant rainfall events (wet anomalies) drylands act as a C sink. During these anomalies the limitation on C uptake switches from water to nitrogen. In the Namib Desert of southern Africa, the N inventory in soil organic matter av...
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doaj-20ba7ddacc0d4eb5afdefd7c70bd76bf2020-12-08T06:12:05ZengNature Publishing GroupScientific Reports2045-23222018-05-01811910.1038/s41598-018-25078-4Namib Desert primary productivity is driven by cryptic microbial community N-fixationJean-Baptiste Ramond0Stephan Woodborne1Grant Hall2Mary Seely3Don A. Cowan4Department of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics (CMEG), Genomics Research Institute (GRI), University of PretoriaMammal Research Institute, University of PretoriaMammal Research Institute, University of PretoriaGobabeb Research and Training CentreDepartment of Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics (CMEG), Genomics Research Institute (GRI), University of PretoriaAbstract Carbon exchange in drylands is typically low, but during significant rainfall events (wet anomalies) drylands act as a C sink. During these anomalies the limitation on C uptake switches from water to nitrogen. In the Namib Desert of southern Africa, the N inventory in soil organic matter available for mineralisation is insufficient to support the observed increase in primary productivity. The C4 grasses that flourish after rainfall events are not capable of N fixation, and so there is no clear mechanism for adequate N fixation in dryland ecosystems to support rapid C uptake. Here we demonstrate that N fixation by photoautotrophic hypolithic communities forms the basis for the N budget for plant productivity events in the Namib Desert. Stable N isotope (δ 15N) values of Namib Desert hypolithic biomass, and surface and subsurface soils were measured over 3 years across dune and gravel plain biotopes. Hypoliths showed significantly higher biomass and lower δ 15N values than soil organic matter. The δ 15N values of hypoliths approach the theoretical values for nitrogen fixation. Our results are strongly indicative that hypolithic communities are the foundation of productivity after rain events in the Namib Desert and are likely to play similar roles in other arid environments.https://doi.org/10.1038/s41598-018-25078-4 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Jean-Baptiste Ramond Stephan Woodborne Grant Hall Mary Seely Don A. Cowan |
spellingShingle |
Jean-Baptiste Ramond Stephan Woodborne Grant Hall Mary Seely Don A. Cowan Namib Desert primary productivity is driven by cryptic microbial community N-fixation Scientific Reports |
author_facet |
Jean-Baptiste Ramond Stephan Woodborne Grant Hall Mary Seely Don A. Cowan |
author_sort |
Jean-Baptiste Ramond |
title |
Namib Desert primary productivity is driven by cryptic microbial community N-fixation |
title_short |
Namib Desert primary productivity is driven by cryptic microbial community N-fixation |
title_full |
Namib Desert primary productivity is driven by cryptic microbial community N-fixation |
title_fullStr |
Namib Desert primary productivity is driven by cryptic microbial community N-fixation |
title_full_unstemmed |
Namib Desert primary productivity is driven by cryptic microbial community N-fixation |
title_sort |
namib desert primary productivity is driven by cryptic microbial community n-fixation |
publisher |
Nature Publishing Group |
series |
Scientific Reports |
issn |
2045-2322 |
publishDate |
2018-05-01 |
description |
Abstract Carbon exchange in drylands is typically low, but during significant rainfall events (wet anomalies) drylands act as a C sink. During these anomalies the limitation on C uptake switches from water to nitrogen. In the Namib Desert of southern Africa, the N inventory in soil organic matter available for mineralisation is insufficient to support the observed increase in primary productivity. The C4 grasses that flourish after rainfall events are not capable of N fixation, and so there is no clear mechanism for adequate N fixation in dryland ecosystems to support rapid C uptake. Here we demonstrate that N fixation by photoautotrophic hypolithic communities forms the basis for the N budget for plant productivity events in the Namib Desert. Stable N isotope (δ 15N) values of Namib Desert hypolithic biomass, and surface and subsurface soils were measured over 3 years across dune and gravel plain biotopes. Hypoliths showed significantly higher biomass and lower δ 15N values than soil organic matter. The δ 15N values of hypoliths approach the theoretical values for nitrogen fixation. Our results are strongly indicative that hypolithic communities are the foundation of productivity after rain events in the Namib Desert and are likely to play similar roles in other arid environments. |
url |
https://doi.org/10.1038/s41598-018-25078-4 |
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