Nitrogen Addition Alleviates Microbial Nitrogen Limitations and Promotes Soil Respiration in a Subalpine Coniferous Forest

Soil microbes are an important component of soil ecosystems that influence material circulation and are involved in the energy flow of ecosystems. The increase in atmospheric nitrogen (N) deposition affects all types of terrestrial ecosystems, including subalpine forests. In general, alpine and high-latitude ecosystems are N limited. Increased N deposition could therefore affect microbial activity and soil respiration. In this study, four levels of N addition, including CK (no N added), N1 (2 g m−2 a−1), N2 (5 g m−2 a−1), and N3 (10 g m−2 a−1), were carried out in a Sichuan redwood forest at the eastern edge of the Tibetan Plateau. The dynamics of soil respiration, major microbial groups, ecoenzymatic stoichiometry, and microbial biomass carbon and nitrogen (MBC and MBN, respectively) were investigated over a year. The results showed that N application significantly increased soil respiration (11%–15%), MBC (5%–9%), MBN (23%–34%), N-acetylglucosidase (56.40%–204.78%), and peroxidase (42.28%–54.87%) activities. The promotion of soil respiration, N-acetylglucosidase, and peroxidase was highest under the N2 treatment. The carbon, nitrogen, and phosphorus metabolism of soil microbes in subalpine forests significantly responded to N application. In the latter stages of N application, microbial metabolism changed from being N restricted to phosphorus restricted, especially under the N2 treatment. Soil bacteria (B) and gram-positive (G+) bacteria were the dominant microbial groups affecting soil respiration. Structural equation modelling indicated that N application significantly promoted soil respiration and microbial biomass, whereas the main microbial groups did not significantly respond to N application. Therefore, we conclude that short-term N addition alleviates microbial nitrogen limitation and promotes soil respiration in the subalpine forest ecosystem that accelerates soil carbon (C) and N cycling. Continuous monitoring is needed to elucidate the underlying mechanisms under long-term N deposition, which may help in forecasting C, N, and P cycling in the alpine region under global climate change.

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Nitrogen Addition Affects Soil Respiration Primarily through Changes in Microbial Community Structure and Biomass in a Subtropical Natural Forest

Forests ◽

10.3390/f10050435 ◽

2019 ◽

Vol 10 (5) ◽

pp. 435 ◽

Cited By ~ 3

Author(s):

Jiacong Zhou ◽

Xiaofei Liu ◽

Jinsheng Xie ◽

Maokui Lyu ◽

Yong Zheng ◽

...

Keyword(s):

Community Structure ◽

Microbial Community ◽

Microbial Biomass ◽

Soil Respiration ◽

Forest Soil ◽

Microbial Community Structure ◽

N Deposition ◽

N Addition ◽

C Cycling ◽

Total Plfa

Forest soil respiration plays an important role in global carbon (C) cycling. Owing to the high degree of C and nitrogen (N) cycle coupling, N deposition rates may greatly influence forest soil respiration, and possibly even global C cycling. Soil microbes play a crucial role in regulating the biosphere–atmosphere C exchange; however, how microbes respond to N addition remains uncertain. To better understand this process, the experiment was performed in the Castanopsis kawakamii Hayata Nature Reserve, in the subtropical zone of China. Treatments involved applying different levels of N (0, 40, and 80 kg ha−2 year−1) over a three-year period (January 2013–December 2015) to explore how soil physicochemical properties, respiration rate, phospholipid fatty acid (PLFA) concentration, and solid state 13C nuclear magnetic resonance responded to various N addition rate. Results showed that high levels of N addition significantly decreased soil respiration; however, low levels of N addition significantly increased soil respiration. High levels of N reduced soil pH and enhanced P and C co-limitation of microorganisms, leading to significant reductions in total PLFA and changes in the structure of microbial communities. Significant linear relationships were observed between annual cumulative respiration and the concentration of microbial biomass (total PLFA, gram-positive bacteria (G+), gram-negative bacteria (G−), total bacteria, and fungi) and the microbial community structure (G+: G− ratio). Taken together, increasing N deposition changed microbial community structure and suppressed microbial biomass, ultimately leading to recalcitrant C accumulation and soil C emissions decrease in subtropical forest.

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Responses of soil respiration to elevated carbon dioxide and nitrogen addition in young subtropical forest ecosystems in China

Biogeosciences ◽

10.5194/bg-7-315-2010 ◽

2010 ◽

Vol 7 (1) ◽

pp. 315-328 ◽

Cited By ~ 84

Author(s):

Q. Deng ◽

G. Zhou ◽

J. Liu ◽

S. Liu ◽

H. Duan ◽

...

Keyword(s):

Soil Respiration ◽

Elevated Co2 ◽

Forest Ecosystems ◽

N Deposition ◽

Subtropical Forest ◽

N Addition ◽

Above Ground Biomass ◽

Respiration Rates ◽

Ambient Co2 ◽

Ambient N Deposition

Abstract. Global climate change in the real world always exhibits simultaneous changes in multiple factors. Prediction of ecosystem responses to multi-factor global changes in a future world strongly relies on our understanding of their interactions. However, it is still unclear how nitrogen (N) deposition and elevated atmospheric carbon dioxide concentration [CO2] would interactively influence forest floor soil respiration in subtropical China. We assessed the main and interactive effects of elevated [CO2] and N addition on soil respiration by growing tree seedlings in ten large open-top chambers under CO2 (ambient CO2 and 700 μmol mol−1) and nitrogen (ambient and 100 kg N ha−1 yr−1) treatments. Soil respiration, soil temperature and soil moisture were measured for 30 months, as well as above-ground biomass, root biomass and soil organic matter (SOM). Results showed that soil respiration displayed strong seasonal patterns with higher values observed in the wet season (April–September) and lower values in the dry season (October–March) in all treatments. Significant exponential relationships between soil respiration rates and soil temperatures, as well as significant linear relationships between soil respiration rates and soil moistures (below 15%) were found. Both CO2 and N treatments significantly affected soil respiration, and there was significant interaction between elevated [CO2] and N addition (p<0.001, p=0.003, and p=0.006, respectively). We also observed that the stimulatory effect of individual elevated [CO2] (about 29% increased) was maintained throughout the experimental period. The positive effect of N addition was found only in 2006 (8.17% increased), and then had been weakened over time. Their combined effect on soil respiration (about 50% increased) was greater than the impact of either one alone. Mean value of annual soil respiration was 5.32 ± 0.08, 4.54 ± 0.10, 3.56 ± 0.03 and 3.53 ± 0.03 kg CO2 m−2 yr−1 in the chambers exposed to elevated [CO2] and high N deposition (CN), elevated [CO2] and ambient N deposition (CC), ambient [CO2] and high N deposition (NN), and ambient [CO2] and ambient N deposition (CK as a control), respectively. Greater above-ground biomass and root biomass was obtained in the CN, CC and NN treatments, and higher soil organic matter was observed only in the CN treatment. In conclusion, the combined effect of elevated [CO2] and N addition on soil respiration was apparent interaction. They should be evaluated in combination in subtropical forest ecosystems in China where the atmospheric CO2 and N deposition have been increasing simultaneously and remarkably.

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Effects of Elevated CO2 Concentration and Nitrogen Addition on Soil Respiration in a Cd-Contaminated Experimental Forest Microcosm

Forests ◽

10.3390/f11030260 ◽

2020 ◽

Vol 11 (3) ◽

pp. 260

Author(s):

Bo Yao ◽

Qiwu Hu ◽

Guihua Zhang ◽

Yafeng Yi ◽

Meijuan Xiao ◽

...

Keyword(s):

Heavy Metal ◽

Soil Respiration ◽

Soil Carbon ◽

Elevated Co2 ◽

Root Biomass ◽

Fine Root ◽

Hydrolytic Enzymes ◽

N Deposition ◽

Fine Root Biomass ◽

N Addition

Forests near rapidly industrialized and urbanized regions are often exposed to elevated CO2, increased N deposition, and heavy metal pollution. To date, the effects of elevated CO2 and/or increased N deposition on soil respiration (Rs) under heavy metal contamination are unclear. In this study, we firstly investigated Rs in Cd-contaminated model forests with CO2 enrichment and N addition in subtropical China. Results showed that Rs in all treatments exhibited similar clear seasonal patterns, with soil temperature being a dominant control. Cadmium addition significantly decreased cumulative soil CO2 efflux by 19% compared to the control. The inhibition of Rs caused by Cd addition was increased by N addition (decreased by 34%) was partially offset by elevated CO2 (decreased by 15%), and was not significantly altered by the combined N addition and rising CO2. Soil pH, microbial biomass carbon, carbon-degrading hydrolytic enzymes, and fine root biomass were also significantly altered by the treatments. A structural equation model revealed that the responses of Rs to Cd stress, elevated CO2, and N addition were mainly mediated by soil carbon-degrading hydrolytic enzymes and fine root biomass. Overall, our findings indicate that N deposition may exacerbate the negative effect of Cd on Rs in Cd-contaminated forests and benefit soil carbon sequestration in the future at increasing atmospheric CO2 levels.

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Nitrogen addition accelerates ecosystem phosphorus cycling at multiple scales in a temperate grassland of Northeast China

10.5194/egusphere-egu2020-1421 ◽

2020 ◽

Author(s):

Haiying Cui ◽

Manuel Delgado-Baquerizo ◽

Wei Sun ◽

Jian-Ying Ma ◽

Wenzheng Song ◽

...

Keyword(s):

Microbial Biomass ◽

Northeast China ◽

Nitrogen Addition ◽

N Deposition ◽

Organic P ◽

N Addition ◽

Resorption Efficiency ◽

P Deficiency ◽

P Mineralization ◽

N Enrichment

Plant phosphorus (P) resorption, mutualistic symbiosis with mycorrhizas, such as arbuscular mycorrhizal fungi (AMF) and soil organic P mineralization are crucial strategies for acquiring sufficient P to meet plant nutrient demand. Which is the main strategy, however, responding to elevated nitrogen (N) addition to alleviate P deficiency caused by N enrichment remains unclear in terrestrial ecosystems. We explored the responses of foliar P resorption of dominate species (Leymus chinensis), soil microbial properties and organic P mineralization to multi-level N addition in a temperate meadow steppe, Northeast China. We found the enhancements in plant biomass, microbial biomass C and N (MBC, MBN), alkaline phosphatase activities (ALP), and phoD gene abundance (main gene coded soil ALP), while the reductions in soil pH, available P, microbial biomass P, and AMF abundance, and no significant responses of foliar P content under simulative N deposition. When the rates exceeded the threshold 10 g N m-2yr-1, plants and microbes had little additional responses to N enrichment. Notably, N addition had distinct effects on three plant P acquisition strategies, that no conspicuous increase in P resorption efficiency, reduced dependence on mutualistic with AMF symbiosis and accelerated organic P mineralization. A positive correlation between ALP activity, phoD gene abundance and P mineralization rate suggested increases in phosphatase activities and its functional gene copies play crucial roles in organic P mineralization. Nitrogen addition aggravated P deficiency to the production of plant and microbial biomass, which further accelerated soil organic P mineralization and foliar P resorption. Due to lack of plasticity in P resorption efficiency and reduced dependence on mutualistic with AMF symbiosis, however, the organic P mineralization dominated in P acquisition to meet increased P demand. Furthermore, the increase in ALP activities, activation of phoD genes and decrease in soil pH were the main pathways to accelerate organic P mineralization and consequently alleviated P deficiency caused by anthropogenic N deposition, especially at conditions of N saturation. Our results provide strong evidences that N addition can accelerate the rate of P cycling and mobilize plant P uptake strategies such as soil organic P mineralization and leaf P resorption, which are important to better maintain sustainable ecosystem development in the more fertilized word.Acknowledgments: This work was supported by the National Key Research and Development Program of China (2016YFC0500602), National Natural Science Foundation of China (31570470, 31870456), the Fundamental Research Funds for the Central Universities (2412018ZD010), and the Program of Introducing Talents of Discipline to Universities (B16011). H.C. acknowledges support from Chinese Scholarship Council (CSC).

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Response of litter decomposition and the soil environment to one-year nitrogen addition in a Schrenk spruce forest in the Tianshan Mountains, China

Scientific Reports ◽

10.1038/s41598-021-04623-8 ◽

2022 ◽

Vol 12 (1) ◽

Author(s):

Zhaolong Ding ◽

Xu Liu ◽

Lu Gong ◽

Xin Chen ◽

Jingjing Zhao ◽

...

Keyword(s):

Nitrogen Deposition ◽

Litter Decomposition ◽

Forest Ecosystems ◽

N Deposition ◽

Tianshan Mountains ◽

Control Treatment ◽

N Addition ◽

Soil Environment ◽

N Application ◽

Positive Effect

AbstractHuman activities have increased the input of nitrogen (N) to forest ecosystems and have greatly affected litter decomposition and the soil environment. But differences in forests with different nitrogen deposition backgrounds. To better understand the response of litter decomposition and soil environment of N-limited forest to nitrogen deposition. We established an in situ experiment to simulate the effects of N deposition on soil and litter ecosystem processes in a Picea schrenkiana forest in the Tianshan Mountains, China. This study included four N treatments: control (no N addition), low N addition (LN: 5 kg N ha−1 a−1), medium N addition (MN: 10 kg N ha−1 a−1) and high N addition (HN: 20 kg N ha−1 a−1). Our results showed that N addition had a significant effect on litter decomposition and the soil environment. Litter mass loss in the LN treatment and in the MN treatment was significantly higher than that in the control treatment. In contrast, the amount of litter lost in the HN treatment was significantly lower than the other treatments. N application inhibited the degradation of lignin but promoted the breakdown of cellulose. The carbon (C), N, and phosphorus (P) contents of litter did not differ significantly among the treatments, but LN promoted the release of C and P. Our results also showed that soil pH decreased with increasing nitrogen application rates, while soil enzyme activity showed the opposite trend. In addition, the results of redundancy analysis (RDA) and correlation analyses showed that the soil environment was closely related to litter decomposition. Soil enzymes had a positive effect on litter decomposition rates, and N addition amplified these correlations. Our study confirmed that N application had effects on litter decomposition and the soil environment in a N-limited P. schrenkiana forest. LN had a strong positive effect on litter decomposition and the soil environment, while HN was significantly negative. Therefore, increased N deposition may have a negative effect on material cycling of similar forest ecosystems in the near future.

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Warming and nitrogen deposition accelerate soil phosphorus cycling in a temperate meadow ecosystem

Soil Research ◽

10.1071/sr19114 ◽

2020 ◽

Vol 58 (1) ◽

pp. 109

Author(s):

Shiwei Gong ◽

Tao Zhang ◽

Jixun Guo

Keyword(s):

Microbial Biomass ◽

Phosphatase Activity ◽

Field Experiments ◽

N Deposition ◽

Available P ◽

N Addition ◽

Soil P ◽

Microbial Biomass P ◽

Total P ◽

P Cycle

Phosphorus (P) is an essential element for living organisms and a major limiting factor in many ecosystems. In recent years, global warming and nitrogen (N) deposition have become increasingly serious, with significant effects on the P cycle in terrestrial ecosystems. A series of studies were carried out on the soil P cycle, but how climate change affects this remains unclear. Field experiments with warming and N addition were implemented since April 2007. Infrared radiators manipulated temperature, and aqueous ammonium nitrate (10 g m–2 year–1) was added to simulate N deposition. Compared with the control, N addition reduced soil total P; warming and N addition decreased soil available P; warming, N addition and warming plus N addition decreased microbial biomass P, but increased litter P; and warming and N addition increased phosphatase activity significantly. Correlation analysis showed that soil total P, available P, microbial biomass P and phosphatase activity were positively correlated with soil temperature and water content. Soil total P was positively correlated with microbial biomass P and phosphatase activity; and available P was positively correlated with microbial biomass P but negatively correlated with litter P. The results showed that warming and N deposition accelerated the soil P cycle by changing soil physical and chemical properties and soil biological activities (microbial and phosphatase activities). However, N addition reduced the capacity of microbes to fix P and reduced microbial biomass P, resulting in losses to the soil P pool, further aggravating P limitation in the Songnen Grassland ecosystem.

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Effects of One-Year Simulated Nitrogen and Acid Deposition on Soil Respiration in a Subtropical Plantation in China

Forests ◽

10.3390/f11020235 ◽

2020 ◽

Vol 11 (2) ◽

pp. 235 ◽

Cited By ~ 2

Author(s):

Shengsheng Xiao ◽

G. Geoff Wang ◽

Chongjun Tang ◽

Huanying Fang ◽

Jian Duan ◽

...

Keyword(s):

Soil Respiration ◽

Acid Deposition ◽

Underlying Mechanism ◽

N Deposition ◽

Interactive Effects ◽

N Addition ◽

Mean Values ◽

Acid Addition ◽

One Year ◽

Co Addition

Atmospheric nitrogen (N) and acid deposition have become global environmental issues and are likely to alter soil respiration (Rs); the largest CO2 source is from soil to the atmosphere. However, to date, much less attention has been focused on the interactive effects and underlying mechanisms of N and acid deposition on Rs, especially for ecosystems that are simultaneously subjected to elevated levels of deposition of both N and acid. Here, to examine the effects of N addition, acid addition, and their interactions with Rs, we conducted a two-way factorial N addition (control, CK; 60 kg N ha−1 a−1, LN; 120 kg N ha−1 a−1, HN) and acid addition (control, CK; pH 4.5, LA; pH 2.5, HA) field experiment in a subtropical plantation in China. Our results showed the following: (1) During the one-year observation period, the seasonal dynamics of Rs presented a single peak curve model, which was closely related to the surface soil temperature. (2) The simulated N deposition and acid deposition significantly decreased the Rs in the subtropical plantation. Compared to the CK plots, the LN and HN treatments reduced the annual mean values of Rs by 41% and 56%, and the annual mean values of Rs were inhibited by 26% and 31% in the LA and HA plots. The inhibition of N application on Rs was stronger than that of the simulated acid deposition. (3) Significant interactions between N addition and acid addition on Rs were detected, and Rs was significantly inhibited under four co-addition treatments. (4) The underlying mechanism and main reason for the responses of Rs to simulated N and acid deposition in this study might be the inhibition of soil microbial biomass and soil enzyme activity due to soil acidification under increased N and acid input.

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Nitrogen Addition Exacerbates the Negative Effect of Throughfall Reduction on Soil Respiration in a Bamboo Forest

Forests ◽

10.3390/f12060724 ◽

2021 ◽

Vol 12 (6) ◽

pp. 724

Author(s):

Yi Wang ◽

Shirong Liu ◽

Junwei Luan ◽

Chen Chen ◽

Chunju Cai ◽

...

Keyword(s):

Soil Respiration ◽

Global Climate ◽

N Deposition ◽

Interactive Effects ◽

Carbon Limitation ◽

N Availability ◽

Bamboo Forest ◽

N Addition ◽

Negative Effect ◽

Throughfall Reduction

Impacts of drought events and nitrogen (N) deposition on forests are increasingly concerning in the context of global climate change, but their effects, in particular, their interactive effects on soil respiration and its components remain unclear. A two-factor random block field experiment was conducted at a subtropical Moso bamboo forest in Southwest China to explore the response of soil respiration (Rs), autotrophic respiration (Ra), and heterotrophic respiration (Rh) to throughfall re-duction and N addition. Our results showed that throughfall reduction significantly decreased Rs, which is mainly attributed to the decrease in Ra as a result of the decline in fine roots biomass. The N addition led to microbial carbon limitation hence significantly decreased Rh, and thus Rs. We also observed the negative effect of throughfall reduction on Rs was exacerbated by N addition, which is attributed to the significant reduction in Ra under the interaction between throughfall reduction N addition. Our findings suggest that Ra tended to respond more sensitively to potential drought, while Rh responds more sensitively to N deposition, and consequently, increased soil N availability caused by N deposition might aggravate the negative effect of expected drought on soil carbon cycling.

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Effects of simulated nitrogen deposition on soil microbial biomass and community function in subtropical evergreen broad-leaved forest

Forest Systems ◽

10.5424/fs/2019283-15404 ◽

2019 ◽

Vol 28 (3) ◽

pp. e018

Author(s):

Jingjing Wang ◽

Jun Cui ◽

Zhen Teng ◽

Wei Fan ◽

Mengran Guan ◽

...

Keyword(s):

Microbial Community ◽

Microbial Biomass ◽

Soil Microbial Biomass ◽

Diversity Indices ◽

N Deposition ◽

N Addition ◽

Soil Microbial ◽

Community Function ◽

Old Growth Forest ◽

Dormant Season

Aim of the study: The aim of this study was to examine the effects of a 5-year simulated nitrogen (N) deposition on soil microbial biomass carbon (MBC), nitrogen (MBN), microbial community activity and diversity in subtropical old-growth forest ecosystems.Area of study: The study was conducted in forest located at subtropical forest in Anhui, east China.Material and methods: Three blocks with three fully randomized plots of 20 m × 20 m with similar forest community and soil conditions were established. The site applied ammonium nitrate (NH4NO3) to simulate N deposition (50 and 100 kg N ha−1 year −1). From three depths (0–10, 10–20 and 20–30 cm), were collected over four seasons (December, March, June and September), and then measured by community-level physiological profiles (CLPPs).Main results: N addition had no significant effect on MBC and MBN. The spatiotemporal variations in MBC and MBN were controlled by seasonality and soil depth. Soil microbial activities and diversity in the growing season (June and September) were apparently higher than the dormant season (March and December), there were significantly lower diversity indices found following N addition in September. However, N addition enhanced microbial activities and increased diversity indices in the dormant season. Redundancy analysis showed that pH, soil moisture, NO3--N and total phosphorus were the most important factors controlling the spatial pattern of microbial metabolic activity.Research highlights: These results suggest that soil microbial community function is more easily influenced than microbial biomass. The site has a trend of P-limited or near-N saturation, and will threaten the whole forest ecosystem with the increasing duration of N addition.Keywords: Nitrogen deposition; Seasonality; Soil microbial biomass; Microbial community; Subtropical old-growth forest.

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Low and High Nitrogen Deposition Rates in Northern Coniferous Forests Have Different Impacts on Aboveground Litter Production, Soil Respiration, and Soil Carbon Stocks

Ecosystems ◽

10.1007/s10021-020-00478-8 ◽

2020 ◽

Vol 23 (7) ◽

pp. 1423-1436 ◽

Cited By ~ 2

Author(s):

Benjamin Forsmark ◽

Annika Nordin ◽

Nadia I. Maaroufi ◽

Tomas Lundmark ◽

Michael J. Gundale

Keyword(s):

Soil Respiration ◽

Net Primary Production ◽

N Deposition ◽

Coniferous Forests ◽

Organic Layer ◽

Litter Production ◽

N Addition ◽

Mass Unit ◽

Soil C ◽

C Storage

AbstractNitrogen (N) deposition can change the carbon (C) sink of northern coniferous forests by changing the balance between net primary production and soil respiration. We used a field experiment in an N poor Pinus sylvestris forest where five levels of N (0, 3, 6, 12, and 50 kg N ha−1 yr−1, n = 6) had been added annually for 12–13 years to investigate how litter C inputs and soil respiration, divided into its autotrophic and heterotrophic sources, respond to different rates of N input, and its subsequent effect on soil C storage. The highest N addition rate (50 kg N ha−1 yr−1) stimulated soil C accumulation in the organic layer by 22.3 kg C kg−1 N added, increased litter inputs by 46%, and decreased soil respiration per mass unit of soil C by 31.2%, mainly by decreasing autotrophic respiration. Lower N addition rates (≤ 12 kg N ha−1 yr−1) had no effect on litter inputs or soil respiration. These results support previous studies reporting on increased litter inputs coupled to impeded soil C mineralization, contributing to enhancing the soil C sink when N is supplied at high rates, but add observations for lower N addition rates more realistic for N deposition. In doing so, we show that litter production in N poor northern coniferous forests can be relatively unresponsive to low N deposition levels, that stimulation of microbial activity at low N additions is unlikely to reduce the soil C sink, and that high levels of N deposition enhance the soil C sink by increasing litter inputs and decreasing soil respiration.

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