scholarly journals Species Differences in Nitrogen Acquisition in Humid Subtropical Forest Inferred From 15N Natural Abundance and Its Response to Tracer Addition

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 991 ◽  
Author(s):  
Geshere Abdisa Gurmesa ◽  
Xiankai Lu ◽  
Per Gundersen ◽  
Qinggong Mao ◽  
Yunting Fang ◽  
...  
Keyword(s):  
Plant Species ◽  
N Uptake ◽  
N Deposition ◽  
Subtropical Forest ◽  
Species Variation ◽  
N Addition ◽  
Subtropical Forests ◽  
The Impact ◽  
N Acquisition ◽  
Leaf N

Differences in nitrogen (N) acquisition patterns between plant species are often reflected in the natural 15N isotope ratios (δ15N) of the plant tissues, however, such differences are poorly understood for co-occurring plants in tropical and subtropical forests. To evaluate species variation in N acquisition traits, we measured leaf N concentration (%N) and δ15N in tree and understory plant species under ambient N deposition (control) and after a decade of N addition at 50 kg N ha−1 yr−1 (N-plots) in an old-growth subtropical forest in southern China. We also measured changes in leaf δ15N after one-year of 15N addition in both the control and N-plots. The results show consistent significant species variation in leaf %N in both control and N-plots, but decadal N addition did not significantly affect leaf %N. Leaf δ15N values were also significantly different among the plant species both in tree and understory layers, and both in control and N-plots, suggesting differences in N acquisition strategies such as variation in N sources and dominant forms of N uptake and dependence on mycorrhizal associations among the co-occurring plant species. Significant differences between the plant species (in both control and N-plots) in changes in leaf δ15N after 15N addition were observed only in the understory plants, indicating difference in access (or use) of deposited N among the plants. Decadal N addition had species-dependent effects on leaf δ15N, suggesting the N acquisition patterns of these plant species are differently affected by N deposition. These results suggest that co-occurring plants in N-rich and subtropical forests vary in their N acquisition traits; these differences need to be accounted for when evaluating the impact of N deposition on N cycling in these ecosystems.

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

2010 ◽  
Vol 7 (1) ◽  
pp. 315-328 ◽  
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.

scholarly journals Different Molecular Characterization of Soil Particulate Fractions under N Deposition in a Subtropical Forest

Forests ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 914
Author(s):  
Jing Geng ◽  
Shulan Cheng ◽  
Huajun Fang ◽  
Jie Pei ◽  
Meng Xu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chemical Structure ◽  
Critical Role ◽  
N Deposition ◽  
Subtropical Forest ◽  
Gas Chromatography Mass Spectrometry ◽  
N Addition ◽  
Pyrolysis Gas ◽  
C Cycle ◽  
N Treatment

Key Findings: Combining physical fractionation and pyrolysis–gas chromatography/mass spectrometry (py-GC/MS) technique can help better understand the dynamics of soil organic matter (SOM). Background and Objectives: SOM plays a critical role in the global carbon (C) cycle. However, its complexity remains a challenge in characterizing chemical molecular composition within SOM and under nitrogen (N) deposition. Materials and Methods: Three particulate organic matter (POM) fractions within SOM and under N treatments were studied from perspectives of distributions, C contents and chemical signatures in a subtropical forest. N addition experiment was conducted with two inorganic N forms (NH4Cl and NaNO3) applied at three rates of 0, 40, 120 kg N ha−1 yr−1. Three particle-size fractions (>250 μm, 53–250 μm and <53 μm) were separated by a wet-sieving method. Py-GC/MS technique was used to differentiate between chemical composition. Results: A progressive proportion transfer of mineral-associated organic matter (MAOM) to fine POM under N treatment was found. Only C content in fine POM was sensitive to N addition. Principal component analyses (PCA) showed that the coarse POM had the largest plant-derived markers (lignins, phenols, long-chain n-alkanes, and n-alkenes). Short-chain n-alkanes and n-alkenes, benzofurans, aromatics and polycyclic aromatic hydrocarbons mainly from black carbon prevailed in the fine POM. N compounds and polysaccharides from microbial products dominated in the MAOM. Factor analysis revealed that the degradation extent of three fractions was largely distinct. The difference in chemical structure among three particulate fractions within SOM was larger than treatments between control and N addition. In terms of N treatment impact, the MAOM fraction had fewer benzofurans compounds and was enriched in polysaccharides, indicating comparatively weaker mineralization and stronger stabilization of these substances. Conclusions: Our findings highlight the importance of chemical structure in SOM pools and help to understand the influence of N deposition on SOM transformation.

scholarly journals Soil Nitrogen and Sulfur Leaching in a Subtropical Forest at a Transition State under Decreasing Atmospheric Deposition

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1798
Author(s):  
Piaopiao Ke ◽  
Gaoyue Si ◽  
Yao Luo ◽  
Zhenglin Cheng ◽  
Qian Yu ◽  
...  
Keyword(s):  
Transition State ◽  
Soil Layer ◽  
N Deposition ◽  
Subtropical Forest ◽  
N Leaching ◽  
N Saturation ◽  
Subtropical Forests ◽  
Net Flux ◽  
Throughfall Deposition

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.

Canopy processing of N deposition increases short‐term leaf N uptake and photosynthesis, but not long‐term N retention for aspen seedlings

2020 ◽  
Author(s):  
Xin Wang ◽  
Bin Wang ◽  
Chengzhang Wang ◽  
Zhenhua Wang ◽  
Jing Li ◽  
...  
Keyword(s):  
N Uptake ◽  
N Deposition ◽  
Short Term ◽  
N Retention ◽  
Leaf N

Fate of atmospheric nitrogen depositions in two Italian temperate mountain forests assessed by isotopic analysis

2020 ◽  
Author(s):  
Luca Da Ros ◽  
Maurizio Ventura ◽  
Mirco Rodeghiero ◽  
Damiano Gianelle ◽  
Giustino Tonon
Keyword(s):  
Forest Canopy ◽  
N Uptake ◽  
Isotopic Signature ◽  
N Deposition ◽  
Forest Growth ◽  
N Availability ◽  
N Addition ◽  
Total N ◽  
Sequestration Potential ◽  
Soil And Water

&lt;p&gt;&lt;strong&gt;Abstract.&lt;/strong&gt; Forests ability to store carbon is strongly connected with the amount of nitrogen (N) that forest ecosystems can retain; N is indeed considered the most limiting nutrient for terrestrial ecosystem's net primary productivity. Since the industrial revolution, human activities have more than doubled the rate of N input into the nitrogen cycle and this could alleviate N limitation thus stimulating plant growth. However, it has been suggested that when N availability exceeds biotic demand and abiotic sinks, additional N can trigger a negative cascade effect: nutrient imbalance, reduced productivity, increased losses of N, eutrophication and acidification of soil and water, leading toward forest decline and net greenhouse gases emissions. The consequences of increased N deposition on forest depend in large share on the fate of N in the ecosystem, which can be simulated and quantified by a fertilization at a known isotopic signature. Nevertheless, most of the tracer experiments performed so far added the fertilizer directly to the forest floor, neglecting the potential role of N uptake by the forest canopy. In the Italian Alps, we are conducting an experiment where both types of N additions (above and below the canopy layer) are performed in two different forest stands, to understand if canopy fertilization better simulates ecological consequences of increased atmospheric N deposition. These field-scale manipulation experiments are willing to test two different hypotheses: i) the N uptake by trees in the above-canopy N addition experimental sites is higher than under-canopy N addition ii) forest growth rate varies with the type of treatment. To describe the fate of the applied N, stable isotope techniques have been adopted: the forest sites, fertilized with NH&lt;sub&gt;4&lt;/sub&gt;NO&lt;sub&gt;3&lt;/sub&gt; at a known isotopic signature, are sampled for all the ecosystem components (plant, soil and water) periodically to determine the total N content and its isotopic signature. The &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N values permit to calculate the recovery of N-fertilizer in tree tissues, soil and leaching-water, allowing us to understand how N allocation varies under these two fertilization strategies and how this affects C sequestration potential. Results regarding the short-term effects over the first 6 years of data collection will be presented.&lt;/p&gt;

scholarly journals Comparative Nitrogen Uptake and Distribution in Corn and Velvetleaf (Abutilon theophrasti)

Weed Science ◽  
2007 ◽  
Vol 55 (2) ◽  
pp. 102-110 ◽  
Author(s):  
John L. Lindquist ◽  
Darren C. Barker ◽  
Stevan Z. Knezevic ◽  
Alexander R. Martin ◽  
Daniel T. Walters
Keyword(s):  
N Uptake ◽  
Soil Nutrient ◽  
Biomass Accumulation ◽  
Field Studies ◽  
Total Biomass ◽  
N Addition ◽  
N Content ◽  
Area Index ◽  
Leaf N Content ◽  
Leaf N

Weeds compete with crops for light, soil water, and nutrients. Nitrogen (N) is the primary limiting soil nutrient. Forecasting the effects of N on growth, development, and interplant competition requires accurate prediction of N uptake and distribution within plants. Field studies were conducted in 1999 and 2000 to determine the effects of variable N addition on monoculture corn and velvetleaf N uptake, the relationship between plant N concentration ([N]) and total biomass, the fraction of N partitioned to leaves, and predicted N uptake and leaf N content. Cumulative N uptake of both species was generally greater in 2000 than in 1999 and tended to increase with increasing N addition. Corn and velvetleaf [N] declined with increasing biomass in both years in a predictable manner. The fraction of N partitioned to corn and velvetleaf leaves varied with thermal time from emergence but was not influenced by year, N addition, or weed density. With the use of the [N]–biomass relationship to forecast N demand, cumulative corn N uptake was accurately predicted for three of four treatments in 1999 but was underpredicted in 2000. Velvetleaf N uptake was accurately predicted in all treatments in both years. Leaf N content (NL, g N m−2leaf) was predicted by the fraction of N partitioned to leaves, predicted N uptake, and observed leaf area index for each species. Average deviations between predicted and observed corn NLwere < 88 and 12% of the observed values in 1999 and 2000, respectively. Velvetleaf NLwas less well predicted, with average deviations ranging from 39 to 248% of the observed values. Results of this research indicate that N uptake in corn and velvetleaf was driven primarily by biomass accumulation. Overall, the approaches outlined in this paper provide reasonable predictions of corn and velvetleaf N uptake and distribution in aboveground tissues.

Increased precipitation magnifies the effects of N addition on performance of invasive plants in subtropical native communities

2021 ◽  
Author(s):  
Xiang-Qin Li ◽  
Sai-Chun Tang ◽  
Yu-Mei Pan ◽  
Chun-Qiang Wei ◽  
Shi-Hong Lü
Keyword(s):  
Invasive Species ◽  
Plant Species ◽  
Aboveground Biomass ◽  
Invasive Plant ◽  
Plant Invasions ◽  
N Deposition ◽  
N Addition ◽  
Native Plant ◽  
Native Plant Species ◽  
Native Communities

Abstract Aims Nitrogen (N) deposition, precipitation and their interaction affect plant invasions in temperate ecosystems with limiting N and water resources, but whether and how they affect plant invasions in subtropical native communities with abundant N and precipitation remains unclear. Methods We constructed in situ artificial communities with 12 common native plant species in a subtropical system and introduced four common invasive plant species and their native counterparts to these communities. We compared plant growth and establishment of introduced invasive species and native counterparts in communities exposed to ambient (CK), N addition (N+), increased precipitation (P+) and N addition plus increased precipitation (P+N+). We also investigated the density and aboveground biomass of communities under such conditions. Important Findings P+ alone did not enhance the performance of invasive species or native counterparts. N+ enhanced only the aboveground biomass and relative density of invasive species. P+N+ enhanced the growth and establishment performance of both invasive species and native counterparts. Most growth and establishment parameters of invasive species were greater than those of native counterparts under N+, P+ and P+N+ conditions. The density and aboveground biomass of native communities established by invasive species were significantly lower than those of native communities established by native counterparts under P+N+ conditions. These results suggest that P+ may magnify the effects of N+ on performance of invasive species in subtropical native communities where N and water are often abundant, which may help to understand the effect of global change on plant invasion in subtropical ecosystems.

Growth, nodulation and N 2 fixation of Sesbania aculeata grown on soil amended with phosphogypsum

2009 ◽  
Vol 57 (3) ◽  
pp. 349-361
Author(s):  
F. Kurdali ◽  
M. Alshamma’a
Keyword(s):  
Beneficial Effect ◽  
Plant Species ◽  
Dry Matter ◽  
N Uptake ◽  
Control Treatment ◽  
Dilution Method ◽  
Dry Matter Content ◽  
P Availability ◽  
Sesbania Aculeata ◽  
The Impact

The impact of five rates of phosphogypsum (PG) (0, 5, 10, 20 and 40 t/ha) on the growth, nodulation and N 2 fixation of dhaincha ( Sesbania aculeata Pers.) was evaluated in a pot experiment, using sorghum ( Sorghum bicolor L.) as a reference crop. N 2 fixation by the legume crop was measured using the 15 N isotope dilution method. The dry matter content of sorghum doubled when the soil was supplied with the lowest rate of PG (5 t/ha). For sesbania, the highest rate of PG (40 t/ha) was found to have a significant effect on the dry matter yield. PG had a beneficial effect on phosphorus (P) accumulation in both plant species, particularly in the nodules of sesbania. The beneficial effect of PG on nodulation and N 2 fixation was more pronounced than on the host plant growth. The highest value of N 2 fixation (67%) was obtained following the addition of 10 t PG/ha, whereas it was only 35% in the control treatment (PG0). The amount of fixed N 2 doubled when the soil was supplied with PG, particularly in the PG10 treatment. The concentration of fluoride (F − ) in the shoots of both plant species was less than 10 mg/kg. In conclusion, PG improved nodulation, N 2 fixation and P availability in the legume species S. aculeata with minimal soil N uptake.

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 input <sup>15</sup>N signatures are reflected in plant <sup>15</sup>N natural abundances in subtropical forests in China

2017 ◽  
Vol 14 (9) ◽  
pp. 2359-2370 ◽  
Author(s):  
Geshere Abdisa Gurmesa ◽  
Xiankai Lu ◽  
Per Gundersen ◽  
Yunting Fang ◽  
Qinggong Mao ◽  
...  
Keyword(s):  
Southern China ◽  
N Deposition ◽  
Pine Forest ◽  
N Cycling ◽  
N Addition ◽  
Inorganic N ◽  
Subtropical Forests ◽  
Broad Leaved Forest ◽  
Soil Δ15n ◽  
Leaved Forest

Abstract. Natural abundance of 15N (δ15N) in plants and soils can provide time-integrated information related to nitrogen (N) cycling within ecosystems, but it has not been well tested in warm and humid subtropical forests. In this study, we used ecosystem δ15N to assess effects of increased N deposition on N cycling in an old-growth broad-leaved forest and a secondary pine forest in a high-N-deposition area in southern China. We measured δ15N of inorganic N in input and output fluxes under ambient N deposition, and we measured N concentration (%N) and δ15N of major ecosystem compartments under ambient deposition and after decadal N addition at 50 kg N ha−1yr−1, which has a δ15N of −0.7 ‰. Our results showed that the total inorganic N in deposition was 15N-depleted (−10 ‰) mainly due to high input of strongly 15N-depleted NH4+-N. Plant leaves in both forests were also 15N-depleted (−4 to −6 ‰). The broad-leaved forest had higher plant and soil %N and was more 15N-enriched in most ecosystem compartments relative to the pine forest. Nitrogen addition did not significantly affect %N in the broad-leaved forest, indicating that the ecosystem pools are already N-rich. However, %N was marginally increased in pine leaves and significantly increased in understory vegetation in the pine forest. Soil δ15N was not changed significantly by the N addition in either forest. However, the N addition significantly increased the δ15N of plants toward the 15N signature of the added N, indicating incorporation of added N into plants. Thus, plant δ15N was more sensitive to ecosystem N input manipulation than %N in these subtropical forests. We interpret the depleted δ15N of plants as an imprint from the high and 15N-depleted N deposition that may dominate the effects of fractionation that are observed in most warm and humid forests. Fractionation during the steps of N cycling could explain the difference between negative δ15N in plants and positive δ15N in soils, and the increase in soil δ15N with depths. Nevertheless, interpretation of ecosystem δ15N from high-N-deposition regions needs to include data on the deposition 15N signal.

Sign in / Sign up

Export Citation Format

Share Document