Responses of temperate steppe to simulated nitrogen deposition: from community structure to ecosystem functions

2020 ◽  
Author(s):  
Yongmei Huang
Keyword(s):  
Nitrogen Deposition ◽  
Net Primary Productivity ◽  
Terrestrial Ecosystems ◽  
N Deposition ◽  
Tracer Experiment ◽  
Ecosystem Functions ◽  
N Recovery ◽  
N Saturation ◽  
N Addition ◽  
Temperate Steppe

<p>Effect of nitrogen deposition on terrestrial ecosystems are one of the hot spots in the study of global change, and the significantly different responses were reported widely among different ecosystems. In this study, field simulated nitrogen deposition experiment was carried out in a temperate steppe, norther China from 2011 to 2018. Treatments were designed as: CK (0 g N/m<sup>2</sup>), N2 level (2 g N/m<sup>2</sup>), N5 level (5 g N/m<sup>2</sup>), N10 level (10 g N/m<sup>2</sup>), N25 level (25 g N/m<sup>2</sup>) and N50 level (50 g N/m<sup>2</sup>). The results showed that the N addition did not cause a noticeable change in the net primary productivity and soil acidification. N addition caused a significant decline in community biodiversity with a major shift in species composition. N utilization strategy, photosynthetic capacity, and water use efficiency of three dominant species behaved differently under N deposition. Soil was the major sink for N deposition testified by the <sup>15</sup>N isotope tracer experiment. N addition decreased soil microorganism and plant <sup>15</sup>N recovery and increased soil of 30-40 cm layer <sup>15</sup>N recovery. N saturation of the temperature steppe would occur when N deposition rate reached 5.4-8.4gN m<sup>-2</sup>a<sup>-1</sup>.</p>

scholarly journals Nitrogen enrichment enhances the dominance of grasses over forbs in a temperate steppe ecosystem

2011 ◽  
Vol 8 (8) ◽  
pp. 2341-2350 ◽  
Author(s):  
L. Song ◽  
X. Bao ◽  
X. Liu ◽  
Y. Zhang ◽  
P. Christie ◽  
...  
Keyword(s):  
Species Richness ◽  
Aboveground Biomass ◽  
N Deposition ◽  
Soil Mineral N ◽  
N Addition ◽  
Soil Mineral ◽  
Temperate Steppe ◽  
Mineral N ◽  
N Concentration ◽  
Steppe Ecosystem

Abstract. Chinese grasslands are extensive natural ecosystems that comprise 40 % of the total land area of the country and are sensitive to N deposition. A field experiment with six N rates (0, 30, 60, 120, 240, and 480 kg N ha−1 yr−1) was conducted at Duolun, Inner Mongolia, during 2005 and 2010 to identify some effects of N addition on a temperate steppe ecosystem. The dominant plant species in the plots were divided into two categories, grasses and forbs, on the basis of species life forms. Enhanced N deposition, even as little as 30 kg N ha−1 yr−1 above ambient N deposition (16 kg N ha−1 yr−1), led to a decline in species richness. The cover of grasses increased with N addition rate but their species richness showed a weak change across N treatments. Both species richness and cover of forbs declined strongly with increasing N deposition as shown by linear regression analysis (p < 0.05). Increasing N deposition elevated aboveground production of grasses but lowered aboveground biomass of forbs. Plant N concentration, plant δ15N and soil mineral N increased with N addition, showing positive relationships between plant δ15N and N concentration, soil mineral N and/or applied N rate. The cessation of N application in the 480 kg N ha−1 yr−1 treatment in 2009 and 2010 led to a slight recovery of the forb species richness relative to total cover and aboveground biomass, coinciding with reduced plant N concentration and soil mineral N. The results show N deposition-induced changes in soil N transformations and plant N assimilation that are closely related to changes in species composition and biomass accumulation in this temperate steppe ecosystem.

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

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.

scholarly journals Frequency and intensity of nitrogen addition alter soil inorganic sulfur fractions, but the effects vary with mowing management in a temperate steppe

2019 ◽  
Vol 16 (14) ◽  
pp. 2891-2904
Author(s):  
Tianpeng Li ◽  
Heyong Liu ◽  
Ruzhen Wang ◽  
Xiao-Tao Lü ◽  
Junjie Yang ◽  
...  
Keyword(s):  
Soil Ph ◽  
Terrestrial Ecosystems ◽  
N Deposition ◽  
Temperate Grassland ◽  
N Availability ◽  
N Addition ◽  
Organic S ◽  
S Uptake ◽  
N Input ◽  
Soil Inorganic

Abstract. Sulfur (S) availability plays a vital role in driving functions of terrestrial ecosystems, which can be largely affected by soil inorganic S fractions and pool size. Enhanced nitrogen (N) input can significantly affect soil S availability, but it still remains largely unknown if the N effect varies with frequency of N addition and mowing management in grasslands. To investigate changes in the soil S pool and inorganic S fractions (soluble S, adsorbed S, available S, and insoluble S), we conducted a field experiment with different frequencies (two times per year vs. monthly additions per year) and intensities (i.e., 0, 1, 2, 3, 5, 10, 15, 20, and 50 g N m−2 yr−1) of NH4NO3 addition and mowing (unmown vs. mown) over 6 years in a temperate grassland of northern China. Generally, N addition frequency, N intensity, and mowing significantly interacted with each other to affect most of the inorganic S fractions. Specifically, a significant increase in soluble S was only found at high N frequency with the increasing intensity of N addition. Increasing N addition intensity enhanced adsorbed S and available S concentrations at low N frequency in unmown plots; however, both fractions were significantly increased with N intensity at both N frequencies in mown plots. The high frequency of N addition increased the concentrations of adsorbed S and available S in comparison to the low frequency of N addition only in mown plots. Changes in soil S fractions were mainly related to soil pH, N availability, soil organic carbon (SOC), and plant S uptake. Our results suggested that N input could temporarily replenish soil-available S by promoting dissolution of soil-insoluble S with decreasing soil pH and mineralization of organic S due to increasing plant S uptake. However, the significant decrease in organic S and total S concentrations with N addition intensity in mown plots indicated that N addition together with biomass removal would eventually cause soil S depletion in this temperate grassland in the long term. Our results further indicated that using large and infrequent N additions to simulate N deposition can overestimate the main effects of N deposition and mowing management on soil S availability in semiarid grasslands.

scholarly journals Nitrogen Additions Retard Nutrient Release from Two Contrasting Foliar Litters in a Subtropical Forest, Southwest China

Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 377 ◽  
Author(s):  
Liyan Zhuang ◽  
Qun Liu ◽  
Ziyi Liang ◽  
Chengming You ◽  
Bo Tan ◽  
...  
Keyword(s):  
Litter Decomposition ◽  
Critical Role ◽  
C:N Ratio ◽  
Terrestrial Ecosystems ◽  
N Deposition ◽  
Decay Rates ◽  
N Addition ◽  
K Value ◽  
P Release ◽  
N Additions

Litter decomposition plays a critical role in regulating biogeochemical cycles in terrestrial ecosystems and is profoundly impacted by increasing atmospheric nitrogen (N) deposition. Here, a N manipulation experiment was conducted to explore the effects of N additions (0 kg N ha−1 yr−1, 20 kg N ha−1 yr−1 and 40 kg N ha−1 yr−1) on decay rates and nutrients release of two contrasting species, the evergreen and nutrient-poor Michelia wilsonii and the deciduous and nutrient-rich Camptotheca acuminata, using a litterbag approach at the western edge of the Sichuan Basin of China. The decay rate and the mineralization of N and phosphorus (P) was faster in nutrient-rich C. acuminata litter than in nutrient-poor M. wilsonii litter, regardless of N regimes. N additions tended to decrease the decay constant (k value) in M. wilsonii litter, but had no effect on C. acuminata litter. N additions had no significant effects on carbon (C) release of both litter types. N additions showed negative effects on N and P release of M. wilsonii litter, particularly in the late decomposition stage. Moreover, for C. acuminata litter, N additions did not affect N release, but retarded P release in the late stage. N additions did not affect the C:N ratio in both litter types. However, N additions—especially high-N addition treatments—tended to reduce C:P and N:P ratios in both species. The effect of N addition on N and P remaining was stronger in M. wilsonii litter than in C. acuminata litter. The results of this study indicate that N additions retarded the nutrients release of two foliar litters. Thus, rising N deposition might favor the retention of N and P via litter decomposition in this specific area experiencing significant N deposition.

Nitrogen deposition and effects on European forests

2000 ◽  
Vol 8 (2) ◽  
pp. 65-93 ◽  
Author(s):  
J W Erisman ◽  
W de Vries
Keyword(s):  
Species Diversity ◽  
Nitrogen Deposition ◽  
Forest Ecosystems ◽  
N Deposition ◽  
Ground Vegetation ◽  
N Saturation ◽  
Input Output ◽  
Soil Response ◽  
Field Evidence ◽  
The Impact

Hypotheses about the impacts of elevated atmospheric deposition of nitrogen on the forest ecosystem include an increased sensitivity to natural stress, impacts on roots, reduced species diversity of the ground vegetation, reduced growth, and unbalanced nutritional status due to eutrophication and acidification. The impact of N deposition has gained in ecological importance during recent decades, in part due to the steady decline in S emissions. Results of throughfall and deposition measurements at 163 plots in Europe show that total deposition of S and N compounds ranged from 100 to 3000 mol ha–1 yr–1 in approximately 90% of the plots, but values up to 4000–8000 mol ha–1 yr–1 were also observed. Approximately 50% of the plots received N inputs, dominated by NH4, above 1000 mol ha–1 yr–1, which is a deposition level at which species diversity of the ground vegetation may be at risk. Results of input–output budgets for plots concentrated in Northern and Western Europe indicate that nitrate leaching starts to occur at throughfall inputs above 10 kg ha–1 yr–1, specifically in soils with C/N ratios in the humus layer below 25. Examples are given of field evidence for impacts of elevated N deposition, including elevated N contents in foliage and soil, Al release in soil response to increased nitrate concentrations, reduced shoot/root ratios, and a reduction in species diversity. Although knowledge about the response of forest ecosystems to N inputs has increased over the last decade, there is still a lack of information on the dynamics of N accumulation and related critical N loads in a range of environmental conditions. Furthermore, a European-wide perspective of N saturation in forest ecosystems is still lacking.Key words: nitrogen, deposition, input–output budgets, nitrogen status, forests, effects.

scholarly journals Quantifying atmospheric nitrogen deposition through a nationwide monitoring network across China

2015 ◽  
Vol 15 (13) ◽  
pp. 18365-18405 ◽  
Author(s):  
W. Xu ◽  
X. S. Luo ◽  
Y. P. Pan ◽  
L. Zhang ◽  
A. H. Tang ◽  
...  
Keyword(s):  
Nitrogen Deposition ◽  
Wet Deposition ◽  
Inorganic Nitrogen ◽  
Monitoring Network ◽  
Terrestrial Ecosystems ◽  
N Deposition ◽  
The Tibetan Plateau ◽  
Deposition Fluxes ◽  
Airborne Concentration ◽  
The Impact

Abstract. Global reactive nitrogen (Nr) deposition to terrestrial ecosystems has increased dramatically since the industrial revolution. This is especially true in recent decades in China due to continuous economic growth. However, there are no comprehensive reports of both measured dry and wet Nr deposition across China. We therefore conducted a multiple-year study during the period mainly from 2010 to 2014 to monitor atmospheric concentrations of five major Nr species of gaseous NH3, NO2 and HNO3, and inorganic nitrogen (NH4+ and NO3−) in both particles and precipitation, based on a Nationwide Nitrogen Deposition Monitoring Network (NNDMN, covering 43 sites) in China. Wet deposition fluxes of Nr species were measured directly; dry deposition fluxes were estimated using airborne concentration measurements and inferential models. Our observations reveal large spatial variations of atmospheric Nr concentrations and dry and wet Nr deposition. The annual average concentrations (1.3–47.0 μg N m−3) and dry plus wet deposition fluxes (2.9–75.2 kg N ha−1 yr−1) of inorganic Nr species ranked by region as North China > Southeast China > Southwest China > Northeast China > Northwest China > the Tibetan Plateau or by land use as urban > rural > background sites, reflecting the impact of anthropogenic Nr emission. Average dry and wet N deposition fluxes were 18.5 and 19.3 kg N ha−1 yr−1, respectively, across China, with reduced N deposition dominating both dry and wet deposition. Our results suggest atmospheric dry N deposition is equally important to wet N deposition at the national scale and both deposition forms should be included when considering the impacts of N deposition on environment and ecosystem health.

scholarly journals Increased microbial sequestration of soil organic carbon under nitrogen deposition over China’s terrestrial ecosystems

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Shu Liao ◽  
Siyi Tan ◽  
Yan Peng ◽  
Dingyi Wang ◽  
Xiangyin Ni ◽  
...  
Keyword(s):  
Meta Analysis ◽  
Terrestrial Ecosystems ◽  
N Deposition ◽  
N Addition ◽  
Soil Organic C ◽  
Organic C ◽  
Soil Microbial ◽  
Biomass Turnover ◽  
Microbial Residues ◽  
Stimulation Of

Abstract Background China’s terrestrial ecosystems have been receiving increasing amounts of reactive nitrogen (N) over recent decades. External N inputs profoundly change microbially mediated soil carbon (C) dynamics, but how elevated N affects the soil organic C that is derived from microbial residues is not fully understood. Here, we evaluated the changes in soil microbial necromass C under N addition at 11 forest, grassland, and cropland sites over China’s terrestrial ecosystems through a meta-analysis based on available data from published articles. Results Microbial necromass C accounted for an average of 49.5% of the total soil organic C across the studied sites, with higher values observed in croplands (53.0%) and lower values in forests (38.6%). Microbial necromass C was significantly increased by 9.5% after N addition, regardless of N forms, with greater stimulation observed for fungal (+ 11.2%) than bacterial (+ 4.5%) necromass C. This increase in microbial necromass C under elevated N was greater under longer experimental periods but showed little variation among different N application rates. The stimulation of soil microbial necromass C under elevated N was proportional to the change in soil organic C. Conclusions The stimulation of microbial residues after biomass turnover is an important pathway for the observed increase in soil organic C under N deposition across China’s terrestrial ecosystems.

scholarly journals Initial shifts in nitrogen impact on ecosystem carbon fluxes in an alpine meadow: patterns and causes

2017 ◽  
Vol 14 (17) ◽  
pp. 3947-3956 ◽  
Author(s):  
Bing Song ◽  
Jian Sun ◽  
Qingping Zhou ◽  
Ning Zong ◽  
Linghao Li ◽  
...  
Keyword(s):  
Alpine Meadow ◽  
Microbial Respiration ◽  
Ecosystem Respiration ◽  
C Sequestration ◽  
N Deposition ◽  
N Saturation ◽  
N Addition ◽  
Soil Microbial ◽  
Soil Microbial Respiration ◽  
Plant Respiration

Abstract. Increases in nitrogen (N) deposition can greatly stimulate ecosystem net carbon (C) sequestration through positive N-induced effects on plant productivity. However, how net ecosystem CO2 exchange (NEE) and its components respond to different N addition rates remains unclear. Using an N addition gradient experiment (six levels: 0, 2, 4, 8, 16, 32 gN m−2 yr−1) in an alpine meadow on the Qinghai–Tibetan Plateau, we explored the responses of different ecosystem C fluxes to an N addition gradient and revealed mechanisms underlying the dynamic responses. Results showed that NEE, ecosystem respiration (ER), and gross ecosystem production (GEP) all increased linearly with N addition rates in the first year of treatment but shifted to N saturation responses in the second year with the highest NEE (−7.77 ± 0.48 µmol m−2 s−1) occurring under an N addition rate of 8 gN m−2 yr−1. The saturation responses of NEE and GEP were caused by N-induced accumulation of standing litter, which limited light availability for plant growth under high N addition. The saturation response of ER was mainly due to an N-induced saturation response of aboveground plant respiration and decreasing soil microbial respiration along the N addition gradient, while decreases in soil microbial respiration under high N addition were caused by N-induced reductions in soil pH. We also found that various components of ER, including aboveground plant respiration, soil respiration, root respiration, and microbial respiration, responded differentially to the N addition gradient. These results reveal temporal dynamics of N impacts and the rapid shift in ecosystem C fluxes from N limitation to N saturation. Our findings bring evidence of short-term initial shifts in responses of ecosystem C fluxes to increases in N deposition, which should be considered when predicting long-term changes in ecosystem net C sequestration.

scholarly journals Effects of nitrogen deposition on growing-season soil methane sink across global forest biomes

2019 ◽  
Author(s):  
Enzai Du ◽  
Nan Xia ◽  
Wim de Vries
Keyword(s):  
Boreal Forest ◽  
Specific Effect ◽  
Terrestrial Ecosystems ◽  
Growing Season ◽  
N Deposition ◽  
N Addition ◽  
Ch4 Flux ◽  
Subtropical Forests ◽  
Low Level ◽  
Ch4 Uptake

Abstract. Anthropogenic alteration of global nitrogen (N) deposition has resulted in profound impacts on soil fluxes of greenhouse gases in terrestrial ecosystems. However, the response of soil methane (CH4) flux to N deposition remains poorly quantified in global forest. Based on a synthesis of experimental results from literature, we evaluated the effects of N deposition on growing-season soil CH4 flux across forest biomes. A distinction was made between low-level N addition that is comparable with the worldwide range in N deposition ( 60 kg N−1 yr−1. The results showed that growing-season soil CH4 flux was significantly affected by N additions, the value being dependent on the N addition level and forest biome. Low-level N addition significantly increased growing-season soil CH4 uptake in boreal forest, while an opposite effect occurred in temperate and subtropical forests. However, high-level N addition significantly decreased growing-season soil CH4 uptake across boreal, temperate, and subtropical forests. At biome scale, current N deposition was estimate to increase growing-season soil CH4 sink by 0.029 Tg CH4 in boreal forest, while it decreased growing-season soil CH4 sink by 0.025 Tg CH4 and 0.051 Tg CH4 in temperate and subtropical forests, respectively. This work improves our understanding of biome-specific effect of N deposition on soil CH4 uptake and identifies knowledge gaps in the effect of N deposition on soil CH4 flux in tropical forest.

scholarly journals Nitrogen enrichment enhances the dominance of grasses over forbs in a temperate steppe ecosystem

2011 ◽  
Vol 8 (3) ◽  
pp. 5057-5082 ◽  
Author(s):  
L. Song ◽  
X. M. Bao ◽  
X. J. Liu ◽  
Y. Zhang ◽  
P. Christie ◽  
...  
Keyword(s):  
Species Richness ◽  
Aboveground Biomass ◽  
N Deposition ◽  
Soil Mineral N ◽  
N Addition ◽  
Soil Mineral ◽  
Temperate Steppe ◽  
Mineral N ◽  
N Concentration ◽  
Steppe Ecosystem

Abstract. Chinese grasslands are extensive natural ecosystems that comprise 40 % of the total land area of the country and are sensitive to N deposition. A field experiment with six N rates (0, 30, 60, 120, 240, and 480 kg N ha−1 yr−1) was conducted at Duolun, Inner Mongolia, during 2005 and 2010 to identify some effects of N addition on a temperature steppe ecosystem. The dominant plant species in the plots were divided into two categories, grasses and forbs, on the basis of species life forms. Enhanced N deposition, even as little as 30 kg N ha−1 yr−1 above ambient N deposition (16 kg N ha−1 yr−1), led to a decline in species richness. The cover of grasses increased with N addition rate but their species richness showed a weak change across N treatments. Both species richness and cover of forbs declined strongly with increasing N deposition as shown by linear regression analysis (p<0.05). Increasing N deposition elevated aboveground production of grasses but lowered aboveground biomass of forbs. Plant N concentration, plant δ15N and soil mineral N increased with N addition, showing positive relationships between plant δ15N and N concentration, soil mineral N and/or applied N rate. The cessation of N application in the 480 kg N ha−1 yr−1 treatment in 2009 and 2010 led to a slight recovery of the forb species richness relative to total cover and aboveground biomass, coinciding with reduced plant N concentration and soil mineral N. The results show that N deposition induced changes in soil N transformations and plant N assimilation that are key to changes in species composition and biomass accumulation in this temperate steppe ecosystem.

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