Biogeochemical Cycles of Nitrogen in Forest Ecosystems

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

Deadline for manuscript submissions: closed (31 March 2022) | Viewed by 8795

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Guest Editor
South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
Interests: nitrogen biogeochemistry; soil carbon sequestration; climate change; forest ecology
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Special Issue Information

Dear Colleagues,

Nitrogen (N) is an essential element for all forms of life on earth, and N cycling is the key to understand the structures and functions of forest ecosystems, which play a central role in regulating regional N balance and mitigating climate changes. Nowadays, global changes, such as elevated N deposition, climate, CO2 fertilization and land uses, have greatly shaped terrestrial N cycling. However, there still remain open questions on what dominates forest N biogeochemical cycling and how it happens under global changes. In this Special Issue of Forests, we explore the processes, patterns, and mechanisms of biogeochemical cycles of N in forest ecosystems under global changes, including but not limited to the following items: N fixation, translocation, transformation, losses (leaching/emission), retention, the fate of N, and the interactions with biological and/or abiotic factors. We encourage studies from all the related field, including experimental studies, monitoring approaches and models, to contribute to this special Issue, in order to promote knowledge and sustainable management for forest ecosystems in the future.

Prof. Dr. Xiankai Lu
Guest Editor

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Keywords

  • Forest ecosystems
  • Nitrogen biogeochemistry
  • Nitrogen cycling
  • Nitrogen transformation
  • Nitrification and denitrification
  • Nitrogen stable isotope
  • Carbon and nitrogen coupling
  • Nitrogen use efficiency
  • Nitrogen sink
  • Global changes
  • Nitrogen deposition

Published Papers (4 papers)

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Research

14 pages, 17055 KiB  
Article
Differed Adaptive Strategies to Nutrient Status between Native and Exotic Mangrove Species
by Ying Wang, Ziming Zhang, Kehong He, Zhangcai Qin, Luhua Xie, Yihan Liu, Yaobei Lin, Jing Wei and Fan Wang
Forests 2022, 13(5), 804; https://0-doi-org.brum.beds.ac.uk/10.3390/f13050804 - 20 May 2022
Cited by 2 | Viewed by 2039
Abstract
To rapidly rehabilitate mangrove forests, exotic mangrove species characterized by high growth rates have been introduced in China, which would undoubtedly affect the nutrient status, nutrient acquisition and utilization strategies of mangrove plants, but the mechanism remains unclear. Qi’ao Island (a suburb of [...] Read more.
To rapidly rehabilitate mangrove forests, exotic mangrove species characterized by high growth rates have been introduced in China, which would undoubtedly affect the nutrient status, nutrient acquisition and utilization strategies of mangrove plants, but the mechanism remains unclear. Qi’ao Island (a suburb of Zhuhai City) has the largest continuous exotic mangrove forests in China, where a mass collection of mangrove soils, plant tissues and tidewater was conducted. Ecological stoichiometric ratios and isotopic compositions were then analyzed to evaluate the ecosystem-scale nutrient status and compare the nutrient acquisition and utilization strategies of native Kandelia obovata (KO) and exotic Sonneratia apetala (SA) species. Soil and foliar C:N:P stoichiometries indicated that there is high P availability but N limitations, while further isotopic evidence indicated that native KO and exotic SA responded differently to the N limitation status. First, native KO seemed to prefer NO3, while exotic SA preferred NH4+, according to the Δ15Nleaf–root (leaf–root δ15N difference) as well as the relationships between foliar δ15N and soil-extracted NH4+ δ15N, and between N and heavy metal contents. This suggested possible inter-specific competition between native KO and exotic SA, leading to different N species’ preferences to maximize resource utilization. Next, native KO likely adopted the “conservative” strategy to ensure survival with reduced investment in N-rich growth components but root systems leading to lower growth rates and higher N use efficiency (NUE) and intrinsic water use efficiency (iWUE), while exotic SA adopted the “aggressive” strategy to ensure fast growth with heavy investment in N-rich growth components, leading to rapid growth and lower NUE and iWUE, and showing signs of invasiveness. Further, native KO is more responsive to aggravated N limitation by enhancing NUE. This study will provide insights into the adaptation of different mangrove species to nutrient limitations and the risks associated with large-scale plantations of exotic mangrove species. Full article
(This article belongs to the Special Issue Biogeochemical Cycles of Nitrogen in Forest Ecosystems)
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17 pages, 4445 KiB  
Article
Assessment of NO2 Purification by Urban Forests Based on the i-Tree Eco Model: Case Study in Beijing, China
by Cheng Gong, Chaofan Xian and Zhiyun Ouyang
Forests 2022, 13(3), 369; https://0-doi-org.brum.beds.ac.uk/10.3390/f13030369 - 22 Feb 2022
Cited by 8 | Viewed by 2392
Abstract
Air quality issues caused by nitrogen dioxide (NO2) have become increasingly serious in Chinese cities in recent years. As important urban green infrastructure, urban forests can mitigate gaseous nitrogen pollution by absorbing NO2 through leaf gas exchange. This study investigated [...] Read more.
Air quality issues caused by nitrogen dioxide (NO2) have become increasingly serious in Chinese cities in recent years. As important urban green infrastructure, urban forests can mitigate gaseous nitrogen pollution by absorbing NO2 through leaf gas exchange. This study investigated spatiotemporal variations in the NO2 removal capacity of urban forests in Beijing city from 2014–2019, based on the i-Tree Eco deposition model. The results show that the annual removal capacity of administrative districts within Beijing city ranged from 14,910 to 17,747 tons, and the largest capacity (2684 tons) was found in the Fangshan district. The annual removal rate of NO2 by urban forests in administrative districts within Beijing was estimated at between 0.50–1.60 g/m2, reaching the highest (1.47 g/m2) in the Mengtougou district. The annual average absorption of NO2 by urban forests can account for 0.14–2.60% of annual total atmospheric NO2 and potentially reduce the NO2 concentration by 0.10–0.34 µg/m3 on average. The results of a principal component analysis suggest that the distribution of urban forests in Beijing is not optimized to maximize their NO2 removal capacity, being higher in suburban areas and lower in urban areas. This study provides insights into botanical NO2 removal capacity in Beijing city to mitigate atmospheric N pollution, addressing the key role of urban forests in improving human wellbeing. Full article
(This article belongs to the Special Issue Biogeochemical Cycles of Nitrogen in Forest Ecosystems)
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13 pages, 6812 KiB  
Article
Soil Nitrogen and Sulfur Leaching in a Subtropical Forest at a Transition State under Decreasing Atmospheric Deposition
by Piaopiao Ke, Gaoyue Si, Yao Luo, Zhenglin Cheng, Qian Yu and Lei Duan
Forests 2021, 12(12), 1798; https://0-doi-org.brum.beds.ac.uk/10.3390/f12121798 - 17 Dec 2021
Cited by 1 | Viewed by 1938
Abstract
Anthropogenic emissions of nitrogen- (N) and sulfur (S)-containing pollutants have declined across China in recent years. However, the responses of N and S depositions and dynamics in soil remain unclear in subtropical forests. In this study, the wet and throughfall depositions of dissolved [...] Read more.
Anthropogenic emissions of nitrogen- (N) and sulfur (S)-containing pollutants have declined across China in recent years. However, the responses of N and S depositions and dynamics in soil remain unclear in subtropical forests. In this study, the wet and throughfall depositions of dissolved inorganic N (DIN) and SO42− were continuously monitored in a mildly polluted subtropical forest in Southeast China in 2017 and 2018. Moreover, these solutes in soil water along the soil profile were monitored in 2018. Throughfall deposition of DIN and S decreased by 59% and 53% in recent 3 years, respectively, which can be majorly attributed to the decreases in wet depositions of NO3 and SO42−. Meanwhile, NH4+ deposition remained relatively stable at this site. Even though N deposition in 2018 was below the N saturation threshold for subtropical forests, significant N leaching still occurred. Excess export of N occurred in the upper soil layer (0–15 cm), reaching 6.86 ± 1.54 kg N/ha/yr, while the deeper soil (15–30 cm) was net sink of N as 8.29 ± 1.71 kg N/ha/yr. Similarly, S was excessively exported from the upper soil with net flux of 14.7 ± 3.15 kg S/ha/yr, while up to 6.37 ± 3.18 kg S/ha/yr of S was retained in the deeper soil. The significant N and S leaching under declined depositions suggested that this site possibly underwent a transition state, recovering from historically high acid deposition. Furthermore, the rainfall intensity remarkably regulated leaching and retention of SO42− and DIN at this site. The impacts of climate changes on N and S dynamics require further long-term monitoring in subtropical forests. Full article
(This article belongs to the Special Issue Biogeochemical Cycles of Nitrogen in Forest Ecosystems)
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14 pages, 2079 KiB  
Article
Influence of Simulated Nitrogen Deposition on the Soil Seed Bank of a Subtropical Evergreen Broadleaved Forest
by Jun Wang, Yao Huang, Qinfeng Guo, Long Yang, Hongfang Lu and Hai Ren
Forests 2021, 12(11), 1538; https://0-doi-org.brum.beds.ac.uk/10.3390/f12111538 - 08 Nov 2021
Cited by 1 | Viewed by 1530
Abstract
Increased nitrogen (N) deposition may have profound effects on forest ecosystems. However, information on the impacts of elevated N deposition on belowground soil seed bank in forests is lacking. In a field experiment, we added N at 50 and 25 kg N ha [...] Read more.
Increased nitrogen (N) deposition may have profound effects on forest ecosystems. However, information on the impacts of elevated N deposition on belowground soil seed bank in forests is lacking. In a field experiment, we added N at 50 and 25 kg N ha−1 year−1 to the canopy (CAN50 and CAN25) and to the understory (UAN50 and UAN25), to determine the effects of N deposition on soil seed bank structure and composition in a subtropical evergreen broadleaved forest. A total of 1545 seedlings belonging to 37 species emerged from the 10 cm-depth soil samples. After 6 years of N addition, soil seed bank density significantly increased at the depth of 0–10 cm under CAN50 treatment relative to the control. N addition did not significantly affect species richness, the Simpson index, Shannon–Wiener index, or Pielou index of the soil seed banks. Seed bank density and species richness were positively correlated with soil organic matter content. For the whole 0–10 cm soil layer, the percentage of total seed abundance and total species richness represented by tree species among the N-addition treatments was ≤9.3% and ≤16.1%, respectively. Soil seed bank composition was similar among UAN25, UAN50, and the control, but canopy N addition and especially CAN50 altered the species composition of the seed bank. Overall, our results indicate that artificial canopy N deposition at 50 kg N ha−1 year−1 but not understory N addition tends to promote seed storage and to change species composition in the soil seed bank. Because of the dominance of shrubs and herbs in the soil seed bank, the potential to regenerate tree species from the soil seed bank is limited in the subtropical evergreen broadleaved forest. Full article
(This article belongs to the Special Issue Biogeochemical Cycles of Nitrogen in Forest Ecosystems)
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