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  The role of periphytic N₂ fixation for stands of macrophytes in the whitewater floodplain (várzea)

Kern, J., & Darwich, A. (2003). The role of periphytic N₂ fixation for stands of macrophytes in the whitewater floodplain (várzea). Amazoniana, 17(3/4), 361-375.

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 Creators:
Kern, Jürgen1, Author           
Darwich, Assad, Author
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1Working Group Tropical Ecology, Max Planck Institute for Limnology, Max Planck Institute for Evolutionary Biology, Max Planck Society, ou_976549              

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Free keywords: nitrogen turnover; N₂ fixation; periphyton; Paspalum; floodplain; Amazonia
 Abstract: In the várzea of Amazon River on Marchantaria Island. N₂ fixation was measured in the root-periphyton complex of three abundant macrophytes, i.e. Paspalum repens, Echinochloa polystachya and Eichhornia crassipes. The short-term study was set at a period of rising water when the biomass production of macrophytes is high. N₂ fixation was low in a main channel that links the river to the lakes, and it was high in Lakes Camaleão and Novo, the latter being a newly formed lake in the young sedimentation area of Marchantaria Island. The main factor controlling N₂ fixation on Marchantaria Island seemed to be O₂. The highest nitrogen input by N₂ fixation was observed in stands of Paspalum repens followed by Echinochloa polystachya and Eichhornia crassipes. Maximum rate of N₂ fixation reached 821.3 nmol N g DW⁻¹ h⁻¹ in the root-periphyton complex of Paspalum repens at Lake Camaleão. Under dark conditions there was always a decline in the rate of N₂ fixation pointing to the predominance of photoautotrophic cyanobacteria. Considering both N₂ fixation in the light and in the dark, related to the biomass of each macrophyte stand, N input in all three macrophyte stands was highest at Lake Novo. Upscaling the rates of N₂ fixation, the input at Lake Novo was 235 kg N ha⁻¹ yr⁻¹, 37 kg N ha⁻¹ yr⁻¹ and 1 kg N ha⁻¹ yr⁻¹ in the stands of Paspalum, Echinochloa and Eichhornia, respectively. It is concluded that Paspalum and its N₂ fixing periphyton has a fertilizing potential that plays an important role for autogenic succession in the várzea

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Language(s): eng - English
 Dates: 2003
 Publication Status: Issued
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 Identifiers: eDoc: 65125
Other: 2260/S 38118
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Title: Amazoniana
Source Genre: Journal
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Pages: - Volume / Issue: 17 (3/4) Sequence Number: - Start / End Page: 361 - 375 Identifier: ISSN: 0065-6755