scholarly journals High fire-derived nitrogen deposition on central African forests

2018 ◽  
Vol 115 (3) ◽  
pp. 549-554 ◽  
Author(s):  
Marijn Bauters ◽  
Travis W. Drake ◽  
Hans Verbeeck ◽  
Samuel Bodé ◽  
Pedro Hervé-Fernández ◽  
...  
Keyword(s):  
Biogeochemical Cycles ◽  
N Deposition ◽  
Congo Basin ◽  
Organic N ◽  
N Availability ◽  
Natural Ecosystems ◽  
Canopy Interception ◽  
Atmospheric N Deposition ◽  
Global Biogeochemical Cycles ◽  
Indirect Impacts

Atmospheric nitrogen (N) deposition is an important determinant of N availability for natural ecosystems worldwide. Increased anthropogenic N deposition shifts the stoichiometric equilibrium of ecosystems, with direct and indirect impacts on ecosystem functioning and biogeochemical cycles. Current simulation data suggest that remote tropical forests still receive low atmospheric N deposition due to a lack of proximate industry, low rates of fossil fuel combustion, and absence of intensive agriculture. We present field-based N deposition data for forests of the central Congo Basin, and use ultrahigh-resolution mass spectrometry to characterize the organic N fraction. Additionally, we use satellite data and modeling for atmospheric N source apportionment. Our results indicate that these forests receive 18.2 kg N hectare−1years−1as wet deposition, with dry deposition via canopy interception adding considerably to this flux. We also show that roughly half of the N deposition is organic, which is often ignored in N deposition measurements and simulations. The source of atmospheric N is predominantly derived from intensive seasonal burning of biomass on the continent. This high N deposition has important implications for the ecology of the Congo Basin and for global biogeochemical cycles more broadly.

scholarly journals Nitrogen balance of a boreal Scots pine forest

2012 ◽  
Vol 9 (8) ◽  
pp. 11201-11237 ◽  
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.

scholarly journals Nitrogen balance of a boreal Scots pine forest

2013 ◽  
Vol 10 (2) ◽  
pp. 1083-1095 ◽  
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 ◽  
N Saturation ◽  
Atmospheric N Deposition ◽  
Drainage Flow ◽  
Nutrient Pools

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 by increasing the availability of reactive nitrogen. The most important components of N pools and fluxes were measured in a boreal Scots pine stand in Hyytiälä, Southern Finland. The measurements 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 in the system, mainly in woody biomass, at 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 inputs 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 equally important sources of N for plant growth. Most of the assimilated 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, but there are no signs of N saturation. Further research is needed to estimate soil N2 fluxes (emission and fixation), which may amount up to several kg N ha−1 yr−1.

scholarly journals Too Much of a Good Thing? Inorganic Nitrogen (N) Inhibits Moss-Associated N2 Fixation But Organic N Can Promote It

2021 ◽  
Author(s):  
Yinliu Wang ◽  
Signe Lett ◽  
Kathrin Rousk
Keyword(s):  
Boreal Forests ◽  
Inorganic Nitrogen ◽  
N Deposition ◽  
Ecosystem Functions ◽  
Organic N ◽  
Inorganic N ◽  
Atmospheric N Deposition ◽  
Moss Species ◽  
The Impact ◽  
N Additions

Abstract Moss-associated nitrogen (N2) fixation is one of the main inputs of new N in pristine ecosystems that receive low amounts of atmospheric N deposition. Previous studies have shown that N2 fixation is inhibited by inorganic N (IN) inputs, but if N2 fixation in mosses is similarly affected by organic N (ON) remains unknown. Here, we assessed N2 fixation in two dominant mosses in boreal forests (Pleurozium schreberi and Sphagnum capillifolium) in response to different levels of N, simulating realistic (up to 4 kg N ha−1 yr−1) and extreme N deposition rates in pristine ecosystems (up to 20 kg N ha−1 yr−1) of IN (NH4NO3) and ON (alanine and urea). We also assessed if N2 fixation can recover from the N additions. In the realistic scenario, N2 fixation was inhibited by increasing NH4NO3 additions in P. schreberi but not in S. capillifolium, and alanine and urea stimulated N2 fixation in both moss species. In contrast, in the extreme N additions, increasing N inputs inhibited N2 fixation in both moss species and all N forms. Nitrogen fixation was more sensitive to N inputs in P. schreberi than in S. capillifolium and was higher in the recovery phase after the realistic compared to the extreme N additions. These results demonstrate that N2 fixation in mosses is less sensitive to organic than inorganic N inputs and highlight the importance of considering different N forms and species-specific responses when estimating the impact of N inputs on ecosystem functions such as moss-associated N2 fixation.

scholarly journals Aridity and plant uptake interact to make dryland soils hotspots for nitric oxide (NO) emissions

2016 ◽  
Vol 113 (19) ◽  
pp. E2608-E2616 ◽  
Author(s):  
Peter M. Homyak ◽  
Joseph C. Blankinship ◽  
Kenneth Marchus ◽  
Delores M. Lucero ◽  
James O. Sickman ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
N Uptake ◽  
N Deposition ◽  
N Availability ◽  
Plant N Uptake ◽  
N Loss ◽  
Atmospheric N Deposition ◽  
Soil Microbial ◽  
California Grassland ◽  
No Emissions

Nitric oxide (NO) is an important trace gas and regulator of atmospheric photochemistry. Theory suggests moist soils optimize NO emissions, whereas wet or dry soils constrain them. In drylands, however, NO emissions can be greatest in dry soils and when dry soils are rewet. To understand how aridity and vegetation interact to generate this pattern, we measured NO fluxes in a California grassland, where we manipulated vegetation cover and the length of the dry season and measured [δ15-N]NO and [δ18-O]NO following rewetting with15N-labeled substrates. Plant N uptake reduced NO emissions by limiting N availability. In the absence of plants, soil N pools increased and NO emissions more than doubled. In dry soils, NO-producing substrates concentrated in hydrologically disconnected microsites. Upon rewetting, these concentrated N pools underwent rapid abiotic reaction, producing large NO pulses. Biological processes did not substantially contribute to the initial NO pulse but governed NO emissions within 24 h postwetting. Plants acted as an N sink, limiting NO emissions under optimal soil moisture. When soils were dry, however, the shutdown in plant N uptake, along with the activation of chemical mechanisms and the resuscitation of soil microbial processes upon rewetting, governed N loss. Aridity and vegetation interact to maintain a leaky N cycle during periods when plant N uptake is low, and hydrologically disconnected soils favor both microbial and abiotic NO-producing mechanisms. Under increasing rates of atmospheric N deposition and intensifying droughts, NO gas evasion may become an increasingly important pathway for ecosystem N loss in drylands.

Plant phenols contents and their changes with nitrogen availability in peatlands of northeastern China

2020 ◽  
Vol 13 (6) ◽  
pp. 713-721
Author(s):  
Di Wu ◽  
Xian-Wei Wang ◽  
Shi-Qi Xu ◽  
Chong-Juan Chen ◽  
Rong Mao ◽  
...  
Keyword(s):  
Climate Warming ◽  
Nutrient Availability ◽  
Nitrogen Availability ◽  
Resource Competition ◽  
N Deposition ◽  
Northeastern China ◽  
Organic N ◽  
N Availability ◽  
Boreal Peatlands ◽  
Leaf N

Abstract Aims Climate warming and increasing nitrogen (N) deposition have influenced plant nutrient status and thus plant carbon (C) fixation and vegetation composition in boreal peatlands. Phenols, which are secondary metabolites in plants for defense and adaptation, also play important roles in regulating peatland C dynamics due to their anti-decomposition properties. However, how the phenolic levels of different functional types of plants vary depending on nutrient availability remain unclear in boreal peatlands. Methods Here, we investigated total phenols contents (TPC) and total tannins contents in leaves of 11 plant species in 18 peatlands of the Great Hing’an Mountains area in northeastern China, and examined their variations with leaf N and phosphorus (P) and underlying mechanisms. Important Findings Shrubs had higher TPC than graminoids, indicating less C allocation to defense and less uptake of organic N in faster-growing and nonmycorrhizal graminoids than in slower-growing and mycorrhizal shrubs. For shrubs, leaf TPC decreased with increasing N contents but was not influenced by changing leaf phosphorus (P) contents, which suggested that shrubs would reduce the C investment for defense with increasing N availability. Differently, leaf TPC of graminoids increased with leaf N contents and decreased with leaf P contents. As graminoids are more N-limited and less P-limited, we inferred that graminoids would increase the defensive C investment under increased nutrient availability. We concluded that shrubs would invest more C in growth than in defense with increasing N availability, but it was just opposite for graminoids, which might be an important mechanism to explain the resource competition and encroachment of shrubs in boreal peatlands in the context of climate warming and ever-increasing N deposition.

scholarly journals Atmospheric N Deposition Increases Organic N Loss from Temperate Forests

Ecosystems ◽  
2007 ◽  
Vol 10 (2) ◽  
pp. 252-262 ◽  
Author(s):  
E. N. J. Brookshire ◽  
H. M. Valett ◽  
S. A. Thomas ◽  
J. R. Webster
Keyword(s):  
Temperate Forests ◽  
N Deposition ◽  
Organic N ◽  
N Loss ◽  
Atmospheric N Deposition

scholarly journals Evaluating the response of ẟ<sup>13</sup>C in <i>Haloxylon ammodendron</i>, a dominant C<sub>4</sub> species in Asian desert ecosystem, to water and nitrogen addition as well as the availability of its ẟ<sup>13</sup>C as the indicator of water use-efficiency

2020 ◽  
Author(s):  
Zixun Chen ◽  
Xuejun Liu ◽  
Xiaoqing Cui ◽  
Yaowen Han ◽  
Guoan Wang ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Water Use Efficiency ◽  
Water Use ◽  
N Deposition ◽  
Desert Ecosystem ◽  
N Availability ◽  
Water Addition ◽  
Haloxylon Ammodendron ◽  
Atmospheric N Deposition ◽  
Use Efficiency

Abstract. Variations in precipitation and atmospheric N deposition affect water and N availability in desert, and thus may have significant effects on desert ecosystems. Haloxylon ammodendron is a dominant plant in Asian desert, and addressing its physiological acclimatization to the changes in precipitation and N deposition can provide an insight into how desert plants adapt extreme environment by physiological adjustment. Carbon isotope ratio (ẟ13C) in plants has been suggested as a sensitive long-term indicator of physiological acclimatization. Therefore, this study evaluated the effect of precipitation change and increasing atmospheric N depositon on ẟ13C of H. ammodendron. Furthermore, Haloxylon ammodendron is a C4 plant, whether its ẟ13C can indicate water use-efficiency (WUE) has not been addressed. In the present study, we designed a field experiment with a completely randomized factorial combination of N and water, and measured ẟ13C, gas exchange and WUE of the assimilating branches of H. ammodendron. ẟ13C in H. ammodendron remained stable under N and water supply, while N addition, water addition and their interaction affected gas exchange and WUE in H. ammodendron. In addition, ẟ13C had no correlation with WUE. This result are associated with the irrelevance between ẟ13C and ci/ca, which might be caused by a special value (0.37) of the degree of bundle-sheath leakiness (φ) or a lower activity of carbonic anhydrase (CA) of H. ammodendron. Thus, ẟ13C of H. ammodendron cannot be used for indicating its WUE.

scholarly journals Evaluating the response of <i>δ</i><sup>13</sup>C in <i>Haloxylon ammodendron</i>, a dominant C<sub>4</sub> species in Asian desert ecosystems, to water and nitrogen addition as well as the availability of its <i>δ</i><sup>13</sup>C as an indicator of water use efficiency

2021 ◽  
Vol 18 (9) ◽  
pp. 2859-2870
Author(s):  
Zixun Chen ◽  
Xuejun Liu ◽  
Xiaoqing Cui ◽  
Yaowen Han ◽  
Guoan Wang ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Water Use Efficiency ◽  
Water Use ◽  
N Deposition ◽  
Bundle Sheath ◽  
N Availability ◽  
Haloxylon Ammodendron ◽  
Atmospheric N Deposition ◽  
Desert Ecosystems ◽  
Use Efficiency

Abstract. Variations in precipitation and atmospheric N deposition affect water and N availability in desert and thus may have significant effects on desert ecosystems. Haloxylon ammodendron is a dominant plant in Asian desert, and addressing its physiological acclimatization to the changes in precipitation and N deposition can provide insight into how desert plants adapt to extreme environments by physiological adjustment. Carbon isotope ratio (δ13C) in plants has been suggested as a sensitive long-term indicator of physiological acclimatization. Therefore, this study evaluated the effect of precipitation change and increasing atmospheric N deposition on δ13C of H. ammodendron. Furthermore, H. ammodendron is a C4 plant; whether its δ13C can indicate water use efficiency (WUE) has not been addressed. In the present study, we designed a field experiment with a completely randomized factorial combination of N and water and measured δ13C and gas exchange of H. ammodendron. Then we calculated the degree of bundle-sheath leakiness (φ) and WUE of the assimilating branches of H. ammodendron. δ13C and φ remained stable under N and water supply, while N addition, water addition and their interaction affected gas exchange and WUE in H. ammodendron. In addition, δ13C had no correlation with WUE. These results were associated with the irrelevance between δ13C and the ratio of intercellular to ambient CO2 concentration (ci / ca), which might be caused by a special value (0.37) of the degree of bundle-sheath leakiness (φ) or a lower activity of carbonic anhydrase (CA) of H. ammodendron. In conclusion, δ13C of H. ammodendron is not sensitive to global change in precipitation and atmospheric N deposition and cannot be used for indicating its WUE.

ATMOSPHERIC N DEPOSITION TO THE COASTAL AREA OF THE BLACK SEA: SOURCES, INTRA-ANNUAL VARIATIONS AND IMPORTANCE FOR BIOGEOCHEMISTRY AND PRODUCTIVITY OF THE SURFACE LAYER

2017 ◽  
Author(s):  
Alla Varenik ◽  
Alla Varenik ◽  
Sergey Konovalov ◽  
Sergey Konovalov
Keyword(s):  
Primary Production ◽  
Black Sea ◽  
Marine Ecosystem ◽  
C:N Ratio ◽  
N Deposition ◽  
Local Source ◽  
The Black Sea ◽  
Coastal Zones ◽  
Atmospheric N Deposition ◽  
Urban Location

Atmospheric precipitations can be an important source of nutrients to open and coastal zones of marine ecosystem. Jickells [1] has published that atmospheric depositions can sup-port 5-25% of nitrogen required to primary production. Bulk atmospheric precipitations have been collected in a rural location at the Black Sea Crimean coast – Katsiveli settlement, and an urban location – Sevastopol city. Samples have been analyzed for inorganic fixed nitrogen (IFN) – nitrate, nitrite, and ammonium. Deposi-tions have been calculated at various space and time scales. The monthly volume weighted mean concentration of IFN increases from summer to winter in both locations. A significant local source of IFN has been revealed for the urban location and this source and its spatial influence have been quantified. IFN deposition with atmospheric precipitations is up to 5% of its background content in the upper 10 m layer of water at the north-western shelf of the Black Sea. Considering Redfield C:N ratio (106:16) and the rate of primary production (PP) in coastal areas of the Black Sea of about 100-130 g C m-2 year-1 we have assessed that average atmospheric IFN depositions may intensify primary production by 4.5% for rural locations, but this value is increased many-fold in urban locations due to local IFN sources.

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