Soil Nitrogen Transformation Pathways Shift Following Deep Tillage in Coastal Wetlands Invaded by <i>Spartina alterniflora</i>

<i>Spartina alterniflora</i> invasion has posed severe ecological threats to coastal wetlands. Deep tillage is considered an effective physical method for ecological restoration in such wetlands; however, its effects on sediment nitrogen transformation processes remain unclear. In this s...

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Main Authors: Jingwen Gao, Pengcheng Jiang, Junzhen Li, Ming Wu, Xuexin Shao, Niu Li
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Diversity
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Online Access:https://www.mdpi.com/1424-2818/17/7/473
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author Jingwen Gao
Pengcheng Jiang
Junzhen Li
Ming Wu
Xuexin Shao
Niu Li
author_facet Jingwen Gao
Pengcheng Jiang
Junzhen Li
Ming Wu
Xuexin Shao
Niu Li
author_sort Jingwen Gao
collection DOAJ
description <i>Spartina alterniflora</i> invasion has posed severe ecological threats to coastal wetlands. Deep tillage is considered an effective physical method for ecological restoration in such wetlands; however, its effects on sediment nitrogen transformation processes remain unclear. In this study, we investigated the impacts of deep tillage on soil physicochemical properties and key nitrogen transformation pathways, including nitrification, denitrification, anammox, and DNRA, across different soil depths (0–10, 10–20, 20–30, 30–50, and 50–100 cm) in <i>Spartina alterniflora</i>-invaded coastal wetlands. Deep tillage significantly restructured the distribution of soil moisture (<i>p</i> < 0.05), pH (<i>p</i> > 0.05), electrical conductivity (<i>p</i> < 0.05), and nutrients, promoting NO<sub>3</sub><sup>−</sup>-N accumulation in deeper layers while reducing NH<sub>4</sub><sup>+</sup>-N concentrations in surface soils (<i>p</i> < 0.05). It markedly enhanced denitrification and DNRA rates (<i>p</i> < 0.05), suppressed surface nitrification (<i>p</i> < 0.05), and altered the vertical distribution of anammox activity. Correlation analysis revealed that NH<sub>4</sub><sup>+</sup>-N and NO<sub>3</sub><sup>−</sup>-N concentrations were the primary drivers of nitrogen transformation, with pH and electrical conductivity playing secondary roles. Overall, deep tillage stimulated nitrogen removal processes and affected net ammonium changes. These findings reveal that deep tillage can stimulate nitrogen removal processes by alleviating soil compaction and altering nitrogen transformation pathways, thus supporting biogeochemical recovery mechanisms after deep tillage. These insights provide scientific guidance for the ecological restoration of Spartina alterniflora-invaded coastal wetlands.
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institution Kabale University
issn 1424-2818
language English
publishDate 2025-07-01
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spelling doaj-art-e2dbf740ee174ae0941ffe4226ff2f0d2025-08-20T03:35:27ZengMDPI AGDiversity1424-28182025-07-0117747310.3390/d17070473Soil Nitrogen Transformation Pathways Shift Following Deep Tillage in Coastal Wetlands Invaded by <i>Spartina alterniflora</i>Jingwen Gao0Pengcheng Jiang1Junzhen Li2Ming Wu3Xuexin Shao4Niu Li5Wetland Ecosystem Research Station of Hangzhou Bay, State Key Laboratory of Wetland Conservation and Restoration, Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Daqiao Road 73, Hangzhou 311400, ChinaWetland Ecosystem Research Station of Hangzhou Bay, State Key Laboratory of Wetland Conservation and Restoration, Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Daqiao Road 73, Hangzhou 311400, ChinaWetland Ecosystem Research Station of Hangzhou Bay, State Key Laboratory of Wetland Conservation and Restoration, Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Daqiao Road 73, Hangzhou 311400, ChinaWetland Ecosystem Research Station of Hangzhou Bay, State Key Laboratory of Wetland Conservation and Restoration, Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Daqiao Road 73, Hangzhou 311400, ChinaWetland Ecosystem Research Station of Hangzhou Bay, State Key Laboratory of Wetland Conservation and Restoration, Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Daqiao Road 73, Hangzhou 311400, ChinaWetland Ecosystem Research Station of Hangzhou Bay, State Key Laboratory of Wetland Conservation and Restoration, Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Daqiao Road 73, Hangzhou 311400, China<i>Spartina alterniflora</i> invasion has posed severe ecological threats to coastal wetlands. Deep tillage is considered an effective physical method for ecological restoration in such wetlands; however, its effects on sediment nitrogen transformation processes remain unclear. In this study, we investigated the impacts of deep tillage on soil physicochemical properties and key nitrogen transformation pathways, including nitrification, denitrification, anammox, and DNRA, across different soil depths (0–10, 10–20, 20–30, 30–50, and 50–100 cm) in <i>Spartina alterniflora</i>-invaded coastal wetlands. Deep tillage significantly restructured the distribution of soil moisture (<i>p</i> < 0.05), pH (<i>p</i> > 0.05), electrical conductivity (<i>p</i> < 0.05), and nutrients, promoting NO<sub>3</sub><sup>−</sup>-N accumulation in deeper layers while reducing NH<sub>4</sub><sup>+</sup>-N concentrations in surface soils (<i>p</i> < 0.05). It markedly enhanced denitrification and DNRA rates (<i>p</i> < 0.05), suppressed surface nitrification (<i>p</i> < 0.05), and altered the vertical distribution of anammox activity. Correlation analysis revealed that NH<sub>4</sub><sup>+</sup>-N and NO<sub>3</sub><sup>−</sup>-N concentrations were the primary drivers of nitrogen transformation, with pH and electrical conductivity playing secondary roles. Overall, deep tillage stimulated nitrogen removal processes and affected net ammonium changes. These findings reveal that deep tillage can stimulate nitrogen removal processes by alleviating soil compaction and altering nitrogen transformation pathways, thus supporting biogeochemical recovery mechanisms after deep tillage. These insights provide scientific guidance for the ecological restoration of Spartina alterniflora-invaded coastal wetlands.https://www.mdpi.com/1424-2818/17/7/473coastal wetland restorationvertical soil stratificationnitrogen cyclingdenitrificationDNRA
spellingShingle Jingwen Gao
Pengcheng Jiang
Junzhen Li
Ming Wu
Xuexin Shao
Niu Li
Soil Nitrogen Transformation Pathways Shift Following Deep Tillage in Coastal Wetlands Invaded by <i>Spartina alterniflora</i>
Diversity
coastal wetland restoration
vertical soil stratification
nitrogen cycling
denitrification
DNRA
title Soil Nitrogen Transformation Pathways Shift Following Deep Tillage in Coastal Wetlands Invaded by <i>Spartina alterniflora</i>
title_full Soil Nitrogen Transformation Pathways Shift Following Deep Tillage in Coastal Wetlands Invaded by <i>Spartina alterniflora</i>
title_fullStr Soil Nitrogen Transformation Pathways Shift Following Deep Tillage in Coastal Wetlands Invaded by <i>Spartina alterniflora</i>
title_full_unstemmed Soil Nitrogen Transformation Pathways Shift Following Deep Tillage in Coastal Wetlands Invaded by <i>Spartina alterniflora</i>
title_short Soil Nitrogen Transformation Pathways Shift Following Deep Tillage in Coastal Wetlands Invaded by <i>Spartina alterniflora</i>
title_sort soil nitrogen transformation pathways shift following deep tillage in coastal wetlands invaded by i spartina alterniflora i
topic coastal wetland restoration
vertical soil stratification
nitrogen cycling
denitrification
DNRA
url https://www.mdpi.com/1424-2818/17/7/473
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