SOIL N2O EMISSION AND ITS RESPONSE TO SIMULATED N DEPOSITION IN THE MAIN FORESTS OF DINGHUSHAN IN SUBTROPICAL CHINA

Abstract. Nitrogen (N) deposition is generally considered to increase soil nitrous oxide (N2O) emission in N-rich forests. In many tropical forests, however, elevated N deposition has caused soil N enrichment and further phosphorus (P) deficiency, and the interaction of N and P to control soil N2O emission remains poorly understood, particularly in forests with different soil N status. In this study, we examined the effects of N and P additions on soil N2O emission in an N-rich old-growth forest and two N-limited younger forests (a mixed and a pine forest) in southern China to test the following hypotheses: (1) soil N2O emission is the highest in old-growth forest due to the N-rich soil; (2) N addition increases N2O emission more in the old-growth forest than in the two younger forests; (3) P addition decreases N2O emission more in the old-growth forest than in the two younger forests; and (4) P addition alleviates the stimulation of N2O emission by N addition. The following four treatments were established in each forest: Control, N addition (150 kg N ha−1 yr−1), P addition (150 kg P ha−1 yr−1), and NP addition (150 kg N ha−1 yr−1 plus 150 kg P ha−1 yr−1). From February 2007 to October 2009, monthly quantification of soil N2O emission was performed using static chamber and gas chromatography techniques. Mean N2O emission was shown to be significantly higher in the old-growth forest (13.9 ± 0.7 µg N2O-N m−2 h−1) than in the mixed (9.9 ± 0.4 µg N2O-N m−2 h−1) or pine (10.8 ± 0.5 µg N2O-N m−2 h−1) forests, with no significant difference between the latter two. N addition significantly increased N2O emission in the old-growth forest but not in the two younger forests. However, both P and NP addition had no significant effect on N2O emission in all three forests, suggesting that P addition alleviated the stimulation of N2O emission by N addition in the old-growth forest. Although P fertilization may alleviate the stimulated effects of atmospheric N deposition on N2O emission in N-rich forests, this effect may only occur under high N deposition and/or long-term P addition, and we suggest future investigations to definitively assess this management strategy and the importance of P in regulating N cycles from regional to global scales.

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Indirect N2O emission due to atmospheric N deposition for the Netherlands

Atmospheric Environment ◽

10.1016/j.atmosenv.2005.06.019 ◽

2005 ◽

Vol 39 (32) ◽

pp. 5827-5838 ◽

Cited By ~ 40

Author(s):

Hugo Denier van der Gon ◽

Albert Bleeker

Keyword(s):

The Netherlands ◽

N2o Emission ◽

N Deposition ◽

Atmospheric N Deposition

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Nitrogen balance of a boreal Scots pine forest

Biogeosciences Discussions ◽

10.5194/bgd-9-11201-2012 ◽

2012 ◽

Vol 9 (8) ◽

pp. 11201-11237 ◽

Cited By ~ 4

Author(s):

J. F. J. Korhonen ◽

M. Pihlatie ◽

J. Pumpanen ◽

H. Aaltonen ◽

P. Hari ◽

...

Keyword(s):

Scots Pine ◽

Boreal Forests ◽

N2o Emission ◽

N Deposition ◽

Organic N ◽

N Availability ◽

Atmospheric N Deposition ◽

Drainage Flow ◽

Nutrient Pools ◽

Scots Pine Forest

Abstract. The productivity of boreal forests is considered to be limited by low nitrogen (N) availability. Increased atmospheric N deposition has altered the functioning and N cycling of these N-sensitive ecosystems. The most important components of N pools and fluxes were measured in a boreal Scots pine stand in Hyytiälä, Southern Finland. The measurement at the site allowed direct estimations of nutrient pools in the soil and biomass, inputs from the atmosphere and outputs as drainage flow and gaseous losses from two micro-catchments. N was accumulating to the system with a rate of 7 kg N ha−1 yr−1. Nitrogen input as atmospheric deposition was 7.4 kg N ha−1 yr−1. Dry deposition and organic N in wet deposition contributed over half of the input in deposition. Total outputs were 0.4 kg N ha−1 yr−1, the most important outputs being N2O emission to the atmosphere and organic N flux in drainage flow. Nitrogen uptake and retranslocation were as important sources of N for plant growth. Most of the uptaken N originated from decomposition of organic matter, and the fraction of N that could originate directly from deposition was about 30%. In conclusion, atmospheric N deposition fertilizes the site considerably.

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Multifactor controls on terrestrial N<sub>2</sub>O flux over North America from 1979 through 2010

Biogeosciences ◽

10.5194/bg-9-1351-2012 ◽

2012 ◽

Vol 9 (4) ◽

pp. 1351-1366 ◽

Cited By ~ 24

Author(s):

X. F. Xu ◽

H. Q. Tian ◽

G. S. Chen ◽

M. L. Liu ◽

W. Ren ◽

...

Keyword(s):

North America ◽

Global Change ◽

Climate Variability ◽

Fertilizer Application ◽

N2o Emission ◽

N Deposition ◽

N Fertilizer ◽

Multiple Factors ◽

Change Factors ◽

Factor Interaction

Abstract. Nitrous oxide (N2O) is a potent greenhouse gas which also contributes to the depletion of stratospheric ozone (O3). However, the magnitude and underlying mechanisms for the spatiotemporal variations in the terrestrial sources of N2O are still far from certain. Using a process-based ecosystem model (DLEM – the Dynamic Land Ecosystem Model) driven by multiple global change factors, including climate variability, nitrogen (N) deposition, rising atmospheric carbon dioxide (CO2), tropospheric O3 pollution, N fertilizer application, and land conversion, this study examined the spatial and temporal variations in terrestrial N2O flux over North America and further attributed these variations to various driving factors. From 1979 to 2010, the North America cumulatively emitted 53.9 ± 0.9 Tg N2O-N (1 Tg = 1012 g), of which global change factors contributed 2.4 ± 0.9 Tg N2O-N, and baseline emission contributed 51.5 ± 0.6 Tg N2O-N. Climate variability, N deposition, O3 pollution, N fertilizer application, and land conversion increased N2O emission while the elevated atmospheric CO2 posed opposite effect at continental level; the interactive effect among multiple factors enhanced N2O emission over the past 32 yr. N input, including N fertilizer application in cropland and N deposition, and multi-factor interaction dominated the increases in N2O emission at continental level. At country level, N fertilizer application and multi-factor interaction made large contribution to N2O emission increase in the United States of America (USA). The climate variability dominated the increase in N2O emission from Canada. N inputs and multiple factors interaction made large contribution to the increases in N2O emission from Mexico. Central and southeastern parts of the North America – including central Canada, central USA, southeastern USA, and all of Mexico – experienced increases in N2O emission from 1979 to 2010. The fact that climate variability and multi-factor interaction largely controlled the inter-annual variations in terrestrial N2O emission at both continental and country levels indicate that projected changes in the global climate system may substantially alter the regime of N2O emission from terrestrial ecosystems during the 21st century. Our study also showed that the interactive effect among global change factors may significantly affect N2O flux, and more field experiments involving multiple factors are urgently needed.

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Short-Term Nitrogen Addition Does Not Significantly Alter the Effects of Seasonal Drought on Leaf Functional Traits in Machilus pauhoi Kanehira Seedlings

Forests ◽

10.3390/f10020078 ◽

2019 ◽

Vol 10 (2) ◽

pp. 78 ◽

Cited By ~ 1

Author(s):

Hua Yu ◽

Dongliang Cheng ◽

Baoyin Li ◽

Chaobin Xu ◽

Zhongrui Zhang ◽

...

Keyword(s):

Functional Traits ◽

C:N Ratio ◽

Leaf Traits ◽

N Deposition ◽

Interactive Effects ◽

N Addition ◽

Subtropical China ◽

Short Term ◽

Leaf Functional Traits ◽

Seasonal Drought

Research Highlights: Short-term nitrogen (N) addition did not significantly alter the effects of seasonal drought on the leaf functional traits in Machilus pauhoi Kanehira seedlings in N-rich subtropical China. Background and Objectives: Seasonal drought and N deposition are major drivers of global environmental change that affect plant growth and ecosystem function in subtropical China. However, no consensus has been reached on the interactive effects of these two drivers. Materials and Methods: We conducted a full-factorial experiment to analyze the single and combined effects of seasonal drought and short-term N addition on chemical, morphological and physiological traits of M. pauhoi seedlings. Results: Seasonal drought (40% of soil field capacity) had significant negative effects on the leaf N concentrations (LNC), phosphorus (P) concentrations (LPC), leaf thickness (LT), net photosynthetic rate (A), transpiration rate (E), stomatal conductance (Gs), and predawn leaf water potential (ψPD), and significant positive effects on the carbon:N (C:N) ratio and specific leaf area (SLA). Short-term N addition (50 kg N·hm−2·year−1 and 100 kg N·hm−2·year−1) tended to decrease the C:N ratio and enhance leaf nutrient, growth, and photosynthetic performance because of increased LNC, LPC, LT, leaf area (LA), SLA, A, E, and ψPD; however, it only had significant effects on LT and Gs. No significant interactive effects on leaf traits were detected. Seasonal drought, short-term N addition, and their interactions had significant effects on soil properties. The soil total C (STC), nitrate N (NO3−-N) and soil total N (STN) concentrations were the main factors that affected the leaf traits. Conclusions: Seasonal drought had a stronger effect on M. pauhoi seedling leaf traits than short-term N deposition, indicating that the interaction between seasonal drought and short-term N deposition may have an additive effecton M. pauhoi seedling growth in N-rich subtropical China.

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Impacts of Nitrogen Addition on Nitrous Oxide Emission: Model-Data Comparison

10.5194/bg-2018-126 ◽

2018 ◽

Author(s):

Yujin Zhang ◽

Minna Ma ◽

Huajun Fang ◽

Dahe Qin ◽

Shulan Cheng ◽

...

Keyword(s):

Nitrous Oxide ◽

Global Climate ◽

Pore Space ◽

Terrestrial Ecosystem ◽

N2o Emission ◽

N Deposition ◽

N2o Emissions ◽

Emission Model ◽

N Addition ◽

N2o Production

Abstract. The contributions of long-lived nitrous oxide (N2O) to the global climate and environment have received increasing attention. Especially, atmospheric nitrogen (N) deposition has substantially increased in recent decades due to extensive use of fossil fuels in industry, which strongly stimulates the N2O emissions of the terrestrial ecosystem. Several models have been developed to simulate N2O emission, but there are still large differences in their N2O emission simulations and responses to atmospheric deposition over global or regional scales. Using observations from N addition experiments in a subtropical forest, this study compared six widely-used N2O models (i.e. DayCENT, DLEM, DNDC, DyN, NOE, and NGAS) to investigate their performances for reproducing N2O emission, and especially the impacts of two types of N additions (i.e. ammonium and nitrate: NH4+ and NO3−, respectively) and two levels (low and high) on N2O emission. In general, the six models reproduced the seasonal variations of N2O emission, but failed to reproduce relatively larger N2O emissions due to NH4+ compared to NO3− additions. Few models indicated larger N2O emission under high N addition levels for both NH4+ and NO3−. Moreover, there were substantial model differences for simulating the ratios of N2O emission from nitrification and denitrification processes due to disagreements in model structures and algorithms. This analysis highlights the need to improve representation of N2O production and diffusion, and the control of soil water-filled pore space on these processes in order to simulate the impacts of N deposition on N2O emission.

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Soil N2O emission in contour hedgerow/crop intercropping system in subtropical China

CHINESE JOURNAL OF ECO-AGRICULTURE ◽

10.3724/sp.j.1011.2013.00700 ◽

2013 ◽

Vol 21 (6) ◽

pp. 700-706

Author(s):

Yan-Hui CHENG ◽

Shu-Hua ZHAO ◽

Qiong MO ◽

Zhong-Lu GUO ◽

Chong-Fa CAI

Keyword(s):

N2o Emission ◽

Subtropical China ◽

Contour Hedgerow

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Effects of N Addition Frequency and Quantity on Hydrocotyle vulgaris Growth and Greenhouse Gas Emissions from Wetland Microcosms

Sustainability ◽

10.3390/su11061520 ◽

2019 ◽

Vol 11 (6) ◽

pp. 1520 ◽

Cited By ~ 4

Author(s):

Qian-Wei Li ◽

Xiao-Ya Zhang ◽

Jun-Qin Gao ◽

Ming-Hua Song ◽

Jin-Feng Liang ◽

...

Keyword(s):

Greenhouse Gas Emissions ◽

Greenhouse Gas ◽

Experimental Period ◽

N2o Emission ◽

N Deposition ◽

N Addition ◽

Soil System ◽

Gas Emissions ◽

Affected Plant ◽

Biomass N

(1) Background: Increased attention has been paid to atmospheric nitrogen (N) deposition caused by human activities. N deposition quantity has seriously affected plant productivity and greenhouse gas emissions in wetlands, but the effects of N deposition frequency remain unclear. (2) Methods: We assembled microcosms, which contained vegetative individuals (ramets) of Hydrocotyle vulgaris and soil and subjected them to three frequencies (N addition 1, 2, and 14 times during the experimental period) crossed with three quantities (5, 15, and 30 g N m−2 yr−1) for 90 days. (3) Results: The quantity of N addition significantly increased the root, stem biomass, and ramets number of H. vulgaris, but decreased the spike biomass. N addition quantity significantly promoted N2O emission and inhibited CH4 emission but had no significant effect on CO2 emission. The increasing frequency of N addition significantly promoted the root-to-shoot ratio and decreased N2O emission under high N addition quantity. (4) Conclusions: In conclusion, N addition alters the reproductive strategy of H. vulgaris and enhances its invasiveness, promoting N2O emission but not the CO2 equivalent of the H. vulgaris-soil system.

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Long-term effects of N deposition on N2O emission in an alpine grassland of Central Asia

CATENA ◽

10.1016/j.catena.2019.104100 ◽

2019 ◽

Vol 182 ◽

pp. 104100 ◽

Cited By ~ 6

Author(s):

Fengzhan Geng ◽

Kaihui Li ◽

Xuejun Liu ◽

Yanming Gong ◽

Ping Yue ◽

...

Keyword(s):

Central Asia ◽

N2o Emission ◽

N Deposition ◽

Alpine Grassland ◽

Long Term Effects

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Responses of nitrous oxide emissions to nitrogen and phosphorus additions in two tropical plantations with N-fixing vs. non-N-fixing tree species

Biogeosciences ◽

10.5194/bg-11-4941-2014 ◽

2014 ◽

Vol 11 (18) ◽

pp. 4941-4951 ◽

Cited By ~ 19

Author(s):

W. Zhang ◽

X. Zhu ◽

Y. Luo ◽

R. Rafique ◽

H. Chen ◽

...

Keyword(s):

Nitrous Oxide ◽

Tree Species ◽

N2o Emission ◽

N Deposition ◽

Tree Plantations ◽

N2o Emissions ◽

N Addition ◽

Leguminous Tree ◽

Tropical Plantations ◽

P Addition

Abstract. Leguminous tree plantations at phosphorus (P) limited sites may result in excess nitrogen (N) and higher rates of nitrous oxide (N2O) emissions. However, the effects of N and P applications on soil N2O emissions from plantations with N-fixing vs. non-N-fixing tree species have rarely been studied in the field. We conducted an experimental manipulation of N and/or P additions in two plantations with Acacia auriculiformis (AA, N-fixing) and Eucalyptus urophylla (EU, non-N-fixing) in South China. The objective was to determine the effects of N or P addition alone, as well as NP application together on soil N2O emissions from these tropical plantations. We found that the average N2O emission from control was greater in the AA (2.3 ± 0.1 kg N2O–N ha−1 yr−1) than in EU plantation (1.9 ± 0.1 kg N2O–N ha−1 yr−1). For the AA plantation, N addition stimulated N2O emission from the soil while P addition did not. Applications of N with P together significantly decreased N2O emission compared to N addition alone, especially in the high-level treatments (decreased by 18%). In the EU plantation, N2O emissions significantly decreased in P-addition plots compared with the controls; however, N and NP additions did not. The different response of N2O emission to N or P addition was attributed to the higher initial soil N status in the AA than that of EU plantation, due to symbiotic N fixation in the former. Our result suggests that atmospheric N deposition potentially stimulates N2O emissions from leguminous tree plantations in the tropics, whereas P fertilization has the potential to mitigate N-deposition-induced N2O emissions from such plantations.

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