Nitrogen Biogeochemical Cycling in Forest Ecosystems

A special issue of Forests (ISSN 1999-4907). This special issue belongs to the section "Forest Meteorology and Climate Change".

Deadline for manuscript submissions: closed (28 November 2023) | Viewed by 9486

Special Issue Editors


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Guest Editor
Stable Isotope Ecology, Institute of Applied Ecology, Chinese Academy of Science, Shenyang, China
Interests: forest ecology; soil N cycling; N deposition; global warming; stable isotope ecology

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Co-Guest Editor
Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China
Interests: carbon and nitrogen biogeochemistry; ecological restoration; global change ecology

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Co-Guest Editor
Stable Isotope Ecology, Institute of Applied Ecology, Chinese Academy of Science, Shenyang, China
Interests: plant nitrogen uptake; gaseous nitrogen loss from soils; forest; agricultural ecosystems

Special Issue Information

Dear Colleagues,

In most terrestrial ecosystems, including forests, nitrogen (N) is a major limiting nutrient for plant growth. Over the recent decades, nitrogen deposition has been rapidly increasing in most regions of the world. Though increased N deposition may alleviate N limitation and increase forest productivity, it usually causes N saturation, soil acidification, nutrient imbalance, biodiversity losses, and so on. Our understanding is not sufficient in terms of monitoring and observation of N deposition into forests, soil N leaching, gaseous N losses, and their responses to N deposition, despite an increasing concern around such issues.

The aims and scopes of the Special Issue are to present the new observations on N deposition, soil N transformations, and their interactions with cycles of carbon and other elements in forest ecosystems worldwide, in order to enhance the associated understandings.

This Special Issue will report N deposition to forests in some under-represented regions and the influences of N deposition on forest N cycling. It has long been a challenge to quantify field gaseous N losses, particularly for N2. We will report the results quantified by 15N tracer techniques. We also explore soil N transformations, using either 15N natural abundance or 15N tracer techniques, and associated microbial composition by gene sequence analysis.

The research related to observations or modeling of N cycling in forests and interaction with other forest structures and functions is welcome.

Prof. Dr. Yunting Fang
Prof. Dr. Dejun Li
Dr. Feifei Zhu
Guest Editors

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Keywords

  • N deposition
  • soil N transformation
  • gaseous N loss
  • forest ecosystem

Published Papers (5 papers)

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Research

17 pages, 2911 KiB  
Article
Chemical Composition and Deposition Characteristics of Precipitation into a Typical Temperate Forest in Northeastern China
by Yingying Wang, Feifei Zhu, Ronghua Kang, Linlin Song, Shaonan Huang, Dan Huang, Kai Huang, Abubakari Said Mgelwa, Geshere Abdisa Gurmesa, Xiaoming Fang and Yunting Fang
Forests 2022, 13(12), 2024; https://doi.org/10.3390/f13122024 - 29 Nov 2022
Cited by 1 | Viewed by 1647
Abstract
The chemical compositions and deposition characteristics of atmospheric precipitation affect the structure and function of forest ecosystems and reflect regional air quality. Although northeastern China constitutes a vital forested area, few relevant studies reveal the chemical composition and the nitrogen (N) and sulphur [...] Read more.
The chemical compositions and deposition characteristics of atmospheric precipitation affect the structure and function of forest ecosystems and reflect regional air quality. Although northeastern China constitutes a vital forested area, few relevant studies reveal the chemical composition and the nitrogen (N) and sulphur (S) deposition characteristics within precipitation. In this study, we monitor precipitation chemistry during 2018–2020 at a rural forested site in northeastern China (the Qingyuan site) and compare it with those from background sites (Mondy in Russia and Ochiishi in Japan) and highly anthropogenically influenced areas (Beijing). The precipitation pH range was 4.7–8.0 (volume-weighted average 6.2). The average concentration of total ions in precipitation was 459 μmol L−1, representing a moderate pollution level. Nitrate (NO3, 73 μmol L−1) and ammonium (NH4+, 133 μmol L−1) were the major anions and cations in the precipitation. Total inorganic nitrogen (TIN) deposition was 12.3–15.9 kg N ha−1 year−1 (NH4+-N deposition accounted for 54–67%), lower than the average level in China (19.4 kg N ha−1 year−1). Annual precipitation sulphate (SO42−) deposition was 4.9–6.7 kg S ha−1 year−1. Seventy-two percent of the precipitation ions at our site originated from human activities. This work has revealed that N and S deposition is an important ion deposition component in atmospheric precipitation in the study of temperate forests in northeastern China. Nitrogen deposition, as a source of vital nutrients in the forest ecosystem, may promote forest growth and, thereby, forest carbon sequestration. Full article
(This article belongs to the Special Issue Nitrogen Biogeochemical Cycling in Forest Ecosystems)
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11 pages, 1541 KiB  
Article
Effects of Increasing pH on Nitrous Oxide and Dinitrogen Emissions from Denitrification in Sterilized and Unsterilized Forest Soils
by Yajing Wang, Wenchao Cao, Jingheng Guo and Minghu Zhang
Forests 2022, 13(10), 1589; https://doi.org/10.3390/f13101589 - 29 Sep 2022
Cited by 4 | Viewed by 1492
Abstract
Denitrification, as an important part of the soil nitrogen cycle, is widely considered to be a major source of nitrous oxide (N2O). Both biotic and abiotic denitrification processes contribute significantly to soil N2O emission, especially under acidic conditions. Increasing [...] Read more.
Denitrification, as an important part of the soil nitrogen cycle, is widely considered to be a major source of nitrous oxide (N2O). Both biotic and abiotic denitrification processes contribute significantly to soil N2O emission, especially under acidic conditions. Increasing soil pH was found to suppress N2O emissions from denitrification, while the underlying mechanism remains uncertain. In this study, we incubated fresh forest soil anaerobically after increasing soil pH and adding nitrate (NO3) under both sterilized and unsterilized conditions. The dynamic changes of NO3, nitrite (NO2), N2O and dinitrogen (N2) were monitored continuously during the 15 days of incubation. The results showed that nitrate reduction rates increased with soil pH in both sterilized and unsterilized soils, with the former having higher rates. The obvious production and consumption of nitrite were found at pH 7.1, rather than at pH 5.5, especially in sterilized soils. In both sterilized and unsterilized soils, accumulative emission of N2O and N2O-N/(N2O+N2)-N product ratios decreased significantly with increasing pH, while N2 showed the opposite trend. In sterilized soils, N2O was the dominant end gas product, accounting for 40.88% and 29.42% of the added nitrate at pH 5.5 and 7.1, respectively. In unsterilized soils, N2 was the only final gas product at pH 7.1 (59.34% of the added nitrate), whereas N2O dominated at pH 5.5 (26.67% of the added nitrate). Our results here showed that increasing soil pH promoted the conversion of N2O to N2 under both sterilized and unsterilized conditions, and highlighted the potential importance of abiotic denitrification on N2O emission. Full article
(This article belongs to the Special Issue Nitrogen Biogeochemical Cycling in Forest Ecosystems)
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16 pages, 2975 KiB  
Article
Spatial Variations of Soil N2 and N2O Emissions from a Temperate Forest: Quantified by the In Situ 15N Labeling Method
by Dan Xi, Yunting Fang and Weixing Zhu
Forests 2022, 13(9), 1347; https://doi.org/10.3390/f13091347 - 24 Aug 2022
Cited by 2 | Viewed by 1379
Abstract
Emissions of dinitrogen (N2) and nitrous oxide (N2O) from soil are important components of the global nitrogen cycle. Soil N2O emissions from terrestrial ecosystems have been well studied. However, patterns and mechanisms of N2 emissions remain [...] Read more.
Emissions of dinitrogen (N2) and nitrous oxide (N2O) from soil are important components of the global nitrogen cycle. Soil N2O emissions from terrestrial ecosystems have been well studied. However, patterns and mechanisms of N2 emissions remain unclear due to the technical difficulty in measuring N2 production. In this study, an in situ 15N labeling method was employed to determine soil N2 and N2O emission rates from the lower, middle, and upper slopes, which correspond to different moisture conditions, in a temperate forest in Northeast China. We found that N2 emissions varied from 85 to 3442 μg N m−2 h−1 across the slopes and were dominated by denitrification. The emissions of bulk N2O (22 to 258 μg N m−2 h−1) and denitrification-derived N2O (14 to 246 μg N m−2 h−1) were significantly lower than N2 emissions from their corresponding slope positions. Both N2 and N2O emissions significantly increased when soils become wetter. The ratios of N2O/(N2O + N2) were significantly higher at the upper and middle slopes (0.22 and 0.20, respectively) compared with those at the lower slope (0.08 ± 0.01). At the catchment scale, N2 accounted for 85% of the total gaseous N losses (N2O + N2). Our study shows that soil moisture drives the patterns of N2 and N2O emissions and field quantification of N2O/(N2O + N2) ratio should further consider the effect of slope position of forest ecosystems to estimate total soil gaseous N losses. Full article
(This article belongs to the Special Issue Nitrogen Biogeochemical Cycling in Forest Ecosystems)
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20 pages, 2787 KiB  
Article
Effects of Excess Nitrogen (N) on Fine Root Growth in Tropical Forests of Contrasting N Status
by Feifei Zhu, Frank S. Gilliam, Jan Mulder, Muneoki Yoh, Jiangming Mo and Xiankai Lu
Forests 2022, 13(8), 1328; https://doi.org/10.3390/f13081328 - 19 Aug 2022
Cited by 2 | Viewed by 1580
Abstract
Elevated nitrogen (N) deposition may further acidify soils in tropical forests. Yet, we have limited evidence on this prediction and it remained unclear how this would affect fine root growth therein. Here, we report responses of fine root biomass, vitality, and chemistry, as [...] Read more.
Elevated nitrogen (N) deposition may further acidify soils in tropical forests. Yet, we have limited evidence on this prediction and it remained unclear how this would affect fine root growth therein. Here, we report responses of fine root biomass, vitality, and chemistry, as well as related soil parameters to eight years of N additions in three tropical forests different in initial soil N status, with one primary forest being N-saturated, and another two younger forests (one secondary forest and one planted forest) less N-rich. Results showed that in the primary forest, fine root biomass decreased and fine root necromass increased following N addition, resulting in lower live fine root proportion (fine root vitality). Declining fine root vitality was associated with fine root Fe accumulation and soil acidification indicated by regression analysis. These alterations of fine root growth and chemistry co-occurred with soil pH decline, soil exchangeable Fe3+ mobilization, exchangeable Ca2+, and Mg2+ depletion after N treatments in the primary forest. In contrast, N addition only elevated fine root K, Al, and Fe content in the secondary forest. In the planted forest, moderate but significant decreases in soil pH, soil exchangeable K+, and Mg2+ were found after N treatment, with fine root biomass negatively correlated with soil exchangeable Al3+ and Al3+/(Ca2+ + Mg2+) ratio. Our results suggested that long-term N fertilization may negatively affect fine root growth, via severed soil acidification, Fe mobilization, and base cation depletion in highly acidified, N-saturated primary tropical forests. Initial forest N status, influenced by different land-use history, mediates N deposition effects on fine root growth. Full article
(This article belongs to the Special Issue Nitrogen Biogeochemical Cycling in Forest Ecosystems)
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15 pages, 4346 KiB  
Article
Soil Moisture Control of NO Turnover and N2O Release in Nitrogen-Saturated Subtropical Forest Soils
by Ronghua Kang, Thomas Behrendt, Jan Mulder and Peter Dörsch
Forests 2022, 13(8), 1291; https://doi.org/10.3390/f13081291 - 14 Aug 2022
Cited by 1 | Viewed by 1627
Abstract
Acid forest soils in South China experience a chronically elevated input of atmospheric nitrogen (N), turning them into hot spots for gaseous N emissions. Soil moisture is known to be a major controller for the partitioning of gaseous N loss to nitric (NO) [...] Read more.
Acid forest soils in South China experience a chronically elevated input of atmospheric nitrogen (N), turning them into hot spots for gaseous N emissions. Soil moisture is known to be a major controller for the partitioning of gaseous N loss to nitric (NO) and nitrous oxide (N2O), which may be of particular relevance in the monsoonal climate of South China. To study this partitioning in more detail, we determined gas phase kinetics of NO and N2O release during laboratory dry-out of acidic surface soils from the headwater catchment TieShanPing (TSP), situated close to Chongqing, SW China. Soils were sampled from two hydrologically distinct environments, a well-drained hill slope (HS), and a periodically flooded groundwater discharge zone (GDZ). Production and consumption of NO were studied in an automated flow-through system purged with NO-free or NO-spiked air. Production rates peaked at 21% and 18% water filled pore space (WFPS) in HS and GDZ soils, respectively, suggesting nitrification as the dominant process of NO formation in both landscape units. In HS soils, maximum production and consumption occurred at the same WFPS, whereas GDZ soils displayed maximum NO consumption at higher WFPS than maximum production, suggesting that denitrification is an important NO sink in GDZ soils. Net N2O release was largest at 100% WFPS and declined steadily during drying. Integrated over the entire range of soil moisture, potential NO-N loss outweighed potential N2O-N loss, suggesting that N-saturated, acid forest soil is an important NO source. Full article
(This article belongs to the Special Issue Nitrogen Biogeochemical Cycling in Forest Ecosystems)
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