The Experts below are selected from a list of 3525 Experts worldwide ranked by ideXlab platform
Changchun Song - One of the best experts on this subject based on the ideXlab platform.
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short term response of co2 emissions to various leaf litters a case study from Freshwater Marshes of northeast china
Wetlands Ecology and Management, 2017Co-Authors: Chao Gong, Changchun Song, Xinhou Zhang, Wenwen Tan, Tianhua QiaoAbstract:Soil organic carbon (SOC) mineralization is an important process of carbon (C) cycling and budgeting associated with litter decomposition in terrestrial ecosystems. Research on altered plant-derived C input on soil C stability due to climate change is controversial and there remains considerable uncertainty in predicting soil C dynamics with the techniques currently available. In this study, we conducted a laboratory incubation experiment to test the effects of single- and mixed-Deyeuxia angustifolia (DA) and Carex lasiocarpa (CL) leaf litter addition on cumulative marshland soil CO2 emission under waterlogged and non-waterlogged conditions in Sanjiang Plain, Northeast China. Results showed that the cumulative CO2 emissions were significantly increased after leaf litter addition in both water conditions, and that the effect was more pronounced for DA amendment than CL regardless of water condition. The cumulative CO2 efflux differed considerably between water conditions after DA addition, whereas no significant differences were found after CL addition. Remarkably impact of leaf litter types on cumulative CO2 evolution was observed overall, water condition and interactions between leaf litter types and water conditions had no significant effect on CO2 emissions, however. There were no non-additive effects of individual leaf litter type on total CO2 efflux of the mixed-leaf litter addition treatments. The results of this study indicate that plant litter input to the C-rich marshy soil can induce rapid changes in SOC decomposition regardless of water conditions and that plant residue effects should be taken into consideration when assessing the dynamics of wetland soil system to the future climate scenarios.
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plant zonation patterns reflected by the differences in plant growth biomass partitioning and root traits along a water level gradient among four common vascular plants in Freshwater Marshes of the sanjiang plain northeast china
Ecological Engineering, 2015Co-Authors: Fuxi Shi, Changchun Song, Xinhou Zhang, Rong Mao, Yuedong Guo, Fuyuan GaoAbstract:Abstract Water level is important in determining plant zonation distribution patterns in Freshwater wetlands. However, the role of whole-plants’ morphological traits in response to water level gradients in accounting for the distribution of marsh species is far from clear. Four typical dominant vascular plants with different distribution patterns (high-elevation species Deyeuxia angustifolia, mid-elevation species Carex lasiocarpa and Glyceria spiculosa, and low-elevation species Carex pseudocuraica) in Freshwater Marshes in the Sanjiang Plain of Northeast China were treated with four static water level conditions (−5, 0, +5, and +15 cm relative to the soil surface), and each plant’s growth characteristics, biomass allocation and root traits were investigated. With the rising water level, the growth of D. angustifolia performed worse than other species, whereas the total biomass, plant height and relative growth rate (RGR) of C. pseudocuraica increased steadily. Compared with the other three species, C. pseudocuraica showed a distinct pattern with increasing water levels in the biomass allocation to photosynthetic and non-photosynthetic organs, as well as for coarse and fine roots. Flooding stress significantly reduced root diameter and C/N ratio but simultaneously increased the specific root length (SRL), specific root area (SRA) and root nitrogen concentration (RNC) for both coarse roots (1st order, >0.2 mm) and fine roots (2nd and 3rd orders,
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litter mass loss and nutrient dynamics of four emergent macrophytes during aerial decomposition in Freshwater Marshes of the sanjiang plain northeast china
Plant and Soil, 2014Co-Authors: Xinhou Zhang, Changchun Song, Guisheng Yang, Rong Mao, Baoxian Tao, Fuxi Shi, Xiaoyan Zhu, Aixin HouAbstract:Background and aims In wetland ecosystems, the litter of emergent macrophytes generally begins to decay while standing, but aerial decomposition has often been overlooked. The goal of this study was therefore to elucidate the processes involved in the decomposition of standing litter of emergent macrophytes in Freshwater Marshes in the Sanjiang Plain, Northeast China.
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litter mass loss and nutrient dynamics of four emergent macrophytes during aerial decomposition in Freshwater Marshes of the sanjiang plain northeast china
Plant and Soil, 2014Co-Authors: Xinhou Zhang, Changchun Song, Guisheng Yang, Rong Mao, Baoxian Tao, Fuxi Shi, Xiaoyan Zhu, Aixin HouAbstract:In wetland ecosystems, the litter of emergent macrophytes generally begins to decay while standing, but aerial decomposition has often been overlooked. The goal of this study was therefore to elucidate the processes involved in the decomposition of standing litter of emergent macrophytes in Freshwater Marshes in the Sanjiang Plain, Northeast China. We used the litterbag method to quantify litter mass loss, microbial respiration rates, and nutrient dynamics of four common emergent macrophytes (Carex lasiocarpa, Deyeuxia angustifolia, Glyceria spiculosa, and Phragmites australis) during one year of aerial decomposition. Following one year of aerial decomposition, the leaf and culm mass losses were 19.3–45.1 % and 14.3–23.1 %, respectively. Litter mass loss was closely related to microbial respiration rates and initial ratios of C:N and C:P. The fact that litter N concentrations increased during aerial decomposition resulted in net N immobilization. After one year of decay, however, there was a net release of P from the standing litter in all cases, but the temporal pattern of P concentrations varied between the decomposing litter of the four different species. Our results provide evidence that the decomposition of standing litter from emergent macrophytes contributes markedly to overall litter decay, and thus is a key component of C and nutrient cycles in temperate wetlands.
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short term effect of nitrogen addition on litter and soil properties in calamagrostis angustifolia Freshwater Marshes of northeast china
Wetlands, 2013Co-Authors: Yanyu Song, Changchun Song, Guisheng Yang, Cuicui Hou, Xiaoyan ZhuAbstract:Nitrogen (N) addition can affect soil organic matter (SOM) decomposition by enhancing soil enzyme activity, increasing labile organic carbon (C) fractions and decreasing litter C/N ratio. This study was designed to investigate the short-term effect of N addition on litter and soil chemical and biological properties in Calamagrostis angustifolia Freshwater Marshes. A field experiment was conducted in which soil was treated with N addition of 0 (N0), 12 (N1), and 24 (N2) g N m−2 year−1, respectively. Above-ground biomass increased by 40 % and 32 % for N1 and N2 treatment, respectively. Added N increased litter C and N concentrations as well as β-glucosidase and invertase activities. However, litter C/N ratio decreased with N addition. N1 treatment increased microbial biomass carbon (MBC) in both topsoil and subsoil, but no changes in dissolved organic carbon (DOC) were observed. Total N concentrations in subsoil increased both in N1 and N2 treatments; NH4 +-N decreased in the N1 treatment, while NO3 −-N increased in the N2 treatment in topsoil. N2 treatment increased β-glucosidase, invertase, and urease activities in both soil layers. The differences in litter and soil characteristics caused by N addition suggest that N addition has the capacity to increase soil C transformation rates in marshland.
Rong Mao - One of the best experts on this subject based on the ideXlab platform.
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effects of litter evenness nitrogen enrichment and temperature on short term litter decomposition in Freshwater Marshes of northeast china
Wetlands, 2017Co-Authors: Xinhou Zhang, Xiaoxin Sun, Rong MaoAbstract:Knowledge about the effects of global change factors on litter decomposition is critical for accurate prediction of future carbon (C) and nutrient cycles in terrestrial ecosystems. Here, we collected Deyeuxia angustifolia and Carex lasiocarpa litters from Freshwater Marshes in Northeast China, and conducted an incubation study to examine the effects of nitrogen (N) enrichment (0 and 25 mg N g−1 litter), temperature (5, 15, and 25 °C), and litter evenness on litter mixing effect and decomposition. Non-additive effects were more common than additive effects during decomposition of litter mixtures, and synergistic effect was detected in two thirds of the litter mixtures. Moreover, litter mixing effects on decomposition varied with N enrichment, incubation temperature, and litter evenness. Both increased proportions of D. angustifolia in litter assemblages and elevated temperature generally accelerated litter decomposition. However, N enrichment slowed litter decomposition at 5 and 15 °C, but had positive or neutral effect at 25 °C. Our results highlight the importance of the interactive effects of N enrichment, temperature, and plant community structure on litter mixing effects during decomposition, and suggest that accelerated litter decomposition induced by climate warming and altered vegetation community would be modulated by N enrichment in Freshwater Marshes of Northeast China.
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plant zonation patterns reflected by the differences in plant growth biomass partitioning and root traits along a water level gradient among four common vascular plants in Freshwater Marshes of the sanjiang plain northeast china
Ecological Engineering, 2015Co-Authors: Fuxi Shi, Changchun Song, Xinhou Zhang, Rong Mao, Yuedong Guo, Fuyuan GaoAbstract:Abstract Water level is important in determining plant zonation distribution patterns in Freshwater wetlands. However, the role of whole-plants’ morphological traits in response to water level gradients in accounting for the distribution of marsh species is far from clear. Four typical dominant vascular plants with different distribution patterns (high-elevation species Deyeuxia angustifolia, mid-elevation species Carex lasiocarpa and Glyceria spiculosa, and low-elevation species Carex pseudocuraica) in Freshwater Marshes in the Sanjiang Plain of Northeast China were treated with four static water level conditions (−5, 0, +5, and +15 cm relative to the soil surface), and each plant’s growth characteristics, biomass allocation and root traits were investigated. With the rising water level, the growth of D. angustifolia performed worse than other species, whereas the total biomass, plant height and relative growth rate (RGR) of C. pseudocuraica increased steadily. Compared with the other three species, C. pseudocuraica showed a distinct pattern with increasing water levels in the biomass allocation to photosynthetic and non-photosynthetic organs, as well as for coarse and fine roots. Flooding stress significantly reduced root diameter and C/N ratio but simultaneously increased the specific root length (SRL), specific root area (SRA) and root nitrogen concentration (RNC) for both coarse roots (1st order, >0.2 mm) and fine roots (2nd and 3rd orders,
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litter mass loss and nutrient dynamics of four emergent macrophytes during aerial decomposition in Freshwater Marshes of the sanjiang plain northeast china
Plant and Soil, 2014Co-Authors: Xinhou Zhang, Changchun Song, Guisheng Yang, Rong Mao, Baoxian Tao, Fuxi Shi, Xiaoyan Zhu, Aixin HouAbstract:Background and aims In wetland ecosystems, the litter of emergent macrophytes generally begins to decay while standing, but aerial decomposition has often been overlooked. The goal of this study was therefore to elucidate the processes involved in the decomposition of standing litter of emergent macrophytes in Freshwater Marshes in the Sanjiang Plain, Northeast China.
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litter mass loss and nutrient dynamics of four emergent macrophytes during aerial decomposition in Freshwater Marshes of the sanjiang plain northeast china
Plant and Soil, 2014Co-Authors: Xinhou Zhang, Changchun Song, Guisheng Yang, Rong Mao, Baoxian Tao, Fuxi Shi, Xiaoyan Zhu, Aixin HouAbstract:In wetland ecosystems, the litter of emergent macrophytes generally begins to decay while standing, but aerial decomposition has often been overlooked. The goal of this study was therefore to elucidate the processes involved in the decomposition of standing litter of emergent macrophytes in Freshwater Marshes in the Sanjiang Plain, Northeast China. We used the litterbag method to quantify litter mass loss, microbial respiration rates, and nutrient dynamics of four common emergent macrophytes (Carex lasiocarpa, Deyeuxia angustifolia, Glyceria spiculosa, and Phragmites australis) during one year of aerial decomposition. Following one year of aerial decomposition, the leaf and culm mass losses were 19.3–45.1 % and 14.3–23.1 %, respectively. Litter mass loss was closely related to microbial respiration rates and initial ratios of C:N and C:P. The fact that litter N concentrations increased during aerial decomposition resulted in net N immobilization. After one year of decay, however, there was a net release of P from the standing litter in all cases, but the temporal pattern of P concentrations varied between the decomposing litter of the four different species. Our results provide evidence that the decomposition of standing litter from emergent macrophytes contributes markedly to overall litter decay, and thus is a key component of C and nutrient cycles in temperate wetlands.
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effect of nitrogen addition on decomposition of calamagrostis angustifolia litters from Freshwater Marshes of northeast china
Ecological Engineering, 2011Co-Authors: Changchun Song, Deyan Liu, Yanyu Song, Guisheng Yang, Rong MaoAbstract:Abstract Wetland ecosystems store a large amount of organic carbon (C) in soils, due to the slow decomposition rates of plant litter and soil organic matter. Increased nitrogen (N) availability induced by human activities and global warming may accelerate litter decomposition and affect soil organic C dynamics in wetlands. In the present study, we investigated the effect of N addition on decomposition of Calamagrostis angustifolia litters from Freshwater Marshes in the Sanjiang Plain of Northeast China under field and laboratory conditions. First, we assessed the changes in initial litter chemical composition and subsequent decomposition following three years of N addition at the rate of 24 g N m−2 year−1 under field conditions. Our results showed that N addition increased litter N concentration and decreased C/N ratio, and thus stimulated litter decomposition. Secondly, we examined the effect of increased N availability (0, 25, 50 and 100 mg N g−1 litter) on litter decomposition under laboratory conditions. Increased exterior N availability also enhanced microbial respiration and increased litter mass loss under both waterlogging and non-waterlogging conditions. In addition, waterlogging conditions inhibited microbial respiration and suppressed litter mass loss. These findings demonstrated that N addition increased litter decomposition rates through improved litter quality and enhanced microbial activity in Freshwater Marshes of Northeast China. This implies that increased N availability accelerates litter decomposition rates, and thus may cause substantial losses of soil C and diminish and even reverse the C sink function of wetlands in the Sanjiang Plain of Northeast China.
Scott C Neubauer - One of the best experts on this subject based on the ideXlab platform.
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saltwater intrusion modifies microbial community structure and decreases denitrification in tidal Freshwater Marshes
Ecosystems, 2019Co-Authors: Scott C Neubauer, Michael F Piehler, Ashley R Smyth, Rima B FranklinAbstract:Environmental changes can alter the interactions between biotic and abiotic ecosystem components in tidal wetlands and therefore impact important ecosystem functions. The objective of this study was to determine how saltwater intrusion affects wetland nutrient biogeochemistry, with a specific focus on the soil microbial communities and physicochemical parameters that control nitrate removal. Our work took place in a tidal Freshwater marsh in South Carolina, USA, where a 3.5-year saltwater intrusion experiment increased porewater salinities from Freshwater to oligohaline levels. We measured rates of denitrification, soil oxygen demand, and dissimilatory nitrate reduction to ammonium (DNRA) and used molecular genetic techniques to assess the abundance and community structure of soil microbes. In soils exposed to elevated salinities, rates of denitrification were reduced by about 70% due to changes in the soil physicochemical environment (higher salinity, higher carbon:nitrogen ratio) and shifts in the community composition of denitrifiers. Saltwater intrusion also affected the microbial community responsible for DNRA, increasing the abundance of genes associated with this process and shifting microbial community composition. Though rates of DNRA were below detection, the microbial community response may be a precursor to increased rates of DNRA with continued saltwater intrusion. Overall, saltwater intrusion reduces the ability of tidal Freshwater Marshes to convert reactive nitrogen to dinitrogen gas and therefore negatively affects their water quality functions. Continued study of the interrelationships between biotic communities, the abiotic environment, and biogeochemical transformations will lead to a better understanding of how the progressive replacement of tidal Freshwater Marshes with brackish analogues will affect the overall functioning of the coastal landscape.
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saltwater intrusion into tidal Freshwater Marshes alters the biogeochemical processing of organic carbon
Biogeosciences, 2013Co-Authors: Scott C Neubauer, Rima B Franklin, David J BerrierAbstract:Environmental perturbations in wetlands affect the integrated plant-microbial-soil system, causing biogeochemical responses that can manifest at local to global scales. The objective of this study was to determine how saltwater intrusion affects carbon mineralization and greenhouse gas production in coastal wetlands. Working with tidal Freshwater marsh soils that had experienced ~ 3.5 yr of in situ saltwater additions, we quantified changes in soil properties, measured extracellular enzyme activity associated with organic matter breakdown, and determined potential rates of anaerobic carbon dioxide (CO 2 ) and methane (CH 4 ) production. Soils from the field plots treated with brackish water had lower carbon content and higher C : N ratios than soils from Freshwater plots, indicating that saltwater intrusion reduced carbon availability and increased organic matter recalcitrance. This was reflected in reduced activities of enzymes associated with the hydrolysis of cellulose and the oxidation of lignin, leading to reduced rates of soil CO 2 and CH 4 production. The effects of long-term saltwater additions contrasted with the effects of short-term exposure to brackish water during three-day laboratory incubations, which increased rates of CO 2 production but lowered rates of CH 4 production. Collectively, our data suggest that the long-term effect of saltwater intrusion on soil CO 2 production is indirect, mediated through the effects of elevated salinity on the quantity and quality of autochthonous organic matter inputs to the soil. In contrast, salinity, organic matter content, and enzyme activities directly influence CH 4 production. Our analyses demonstrate that saltwater intrusion into tidal Freshwater Marshes affects the entire process of carbon mineralization, from the availability of organic carbon through its terminal metabolism to CO 2 and/or CH 4 , and illustrate that long-term shifts in biogeochemical functioning are not necessarily consistent with short-term disturbance-type responses.
Michael G Ryan - One of the best experts on this subject based on the ideXlab platform.
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ecosystem resistance in the face of climate change a case study from the Freshwater Marshes of the florida everglades
Ecosphere, 2015Co-Authors: Steven F Oberbauer, Sparkle L Malone, Christina L Staudhammer, Michael G Ryan, C Keough, William J Parton, Paulo C Olivas, Jessica L SchedlbauerAbstract:Shaped by the hydrology of the Kissimmee-Okeechobee-Everglades watershed, the Florida Everglades is composed of a conglomerate of wetland ecosystems that have varying capacities to sequester and store carbon. Hydrology, which is a product of the region's precipitation and temperature patterns combined with water management policy, drives community composition and productivity. As shifts in both precipitation and air temperature are expected over the next 100 years as a consequence of climate change, CO2 dynamics in the greater Everglades are expected to change. To reduce uncertainties associated with climate change and to explore how projected changes in atmospheric CO2 concentration and climate can alter current CO2 exchange rates in Everglades Freshwater marsh ecosystems, we simulated fluxes of carbon among the atmosphere, vegetation, and soil using the DAYCENT model. We explored the effects of low, moderate, and high scenarios for atmospheric CO2 (550, 850, and 950 ppm), mean annual air temperature (+1...
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effects of simulated drought on the carbon balance of everglades short hydroperiod marsh
Global Change Biology, 2013Co-Authors: Gregory Starr, Sparkle L Malone, Christina L Staudhammer, Michael G RyanAbstract:Hydrology drives the carbon balance of wetlands by controlling the uptake and release of CO2 and CH4 . Longer dry periods in between heavier precipitation events predicted for the Everglades region, may alter the stability of large carbon pools in this wetland's ecosystems. To determine the effects of drought on CO2 fluxes and CH4 emissions, we simulated changes in hydroperiod with three scenarios that differed in the onset rate of drought (gradual, intermediate, and rapid transition into drought) on 18 Freshwater wetland monoliths collected from an Everglades short-hydroperiod marsh. Simulated drought, regardless of the onset rate, resulted in higher net CO2 losses net ecosystem exchange (NEE) over the 22-week manipulation. Drought caused extensive vegetation dieback, increased ecosystem respiration (Reco ), and reduced carbon uptake gross ecosystem exchange (GEE). Photosynthetic potential measured by reflective indices (photochemical reflectance index, water index, normalized phaeophytinization index, and the normalized difference vegetation index) indicated that water stress limited GEE and inhibited Reco . As a result of drought-induced dieback, NEE did not offset methane production during periods of inundation. The average ratio of net CH4 to NEE over the study period was 0.06, surpassing the 100-year greenhouse warming compensation point for CH4 (0.04). Drought-induced diebacks of sawgrass (C3 ) led to the establishment of the invasive species torpedograss (C4 ) when water was resupplied. These changes in the structure and function indicate that Freshwater marsh ecosystems can become a net source of CO2 and CH4 to the atmosphere, even following an extended drought. Future changes in precipitation patterns and drought occurrence/duration can change the carbon storage capacity of Freshwater Marshes from sinks to sources of carbon to the atmosphere. Therefore, climate change will impact the carbon storage capacity of Freshwater Marshes by influencing water availability and the potential for positive feedbacks on radiative forcing.
Yiyong Wang - One of the best experts on this subject based on the ideXlab platform.
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the variation of methane emission from Freshwater Marshes and response to the exogenous n in sanjiang plain northeast china
Atmospheric Environment, 2007Co-Authors: Lihua Zhang, Changchun Song, Dexuan Wang, Yiyong WangAbstract:Abstract The methane emitted from Freshwater marsh is the difference between the production and oxidation of CH 4 which reaches the atmosphere via diffusion, ebullition, or by passage through aerenchymous tissues of higher plants. To evaluate the variation of CH 4 emission and the effects of increased exogenous N on CH 4 emission, we have raised in situ the exogenous N with the rates of 0 g N m - 2 (control), 6 g N m - 2 (low nitrogen level), 12 g N m - 2 (medial nitrogen level) and 24 g N m - 2 (high nitrogen level), respectively, in Sanjiang Plain marsh ecosystem Northeast China. CH 4 emissions were measured using the static chamber and gas chromatogram techniques. The daily average CH 4 emission during the different growing stages from the marsh varies from - 0.06 to 13.54 mg CH 4 m - 2 h - 1 with the daily observation. The exogenous N significantly increased the mean seasonal CH 4 emission rate by 181% (low nitrogen level, P 0.01 ), 254% (medial nitrogen level, P 0.01 ) and 155% (high nitrogen level, P 0.01 ), respectively. The effects of exogenous N strongly interacted with the plant aboveground biomass, which was a variable explaining most variation in CH 4 emission. We also find the net effect of exogenous N on CH 4 emission from Freshwater Marshes most likely depends on the counterbalance between the N-induced increases in CH 4 production and oxidation, as a N excess may result in the inhibition of CH 4 emission, and in the stimulation of CH 4 emission.
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effects of nitrogen on the ecosystem respiration ch4 and n2o emissions to the atmosphere from the Freshwater Marshes in northeast china
Environmental Earth Sciences, 2007Co-Authors: Lihua Zhang, Changchun Song, Dexuan Wang, Xunhua Zheng, Yiyong WangAbstract:Freshwater Marshes could be a source of greenhouse gases emission because they contain large amounts of soil carbon and nitrogen. These emissions are strongly influenced by exogenous nitrogen. We investigate the effects of exogenous nitrogen on ecosystem respiration (CO2), CH4 and N2O emissions from Freshwater Marshes in situ in the Sanjiang Plain Northeast of China during the growing seasons of 2004 and 2005, using a field fertilizer experiment and the static opaque chamber/GC techniques. The results show that there were no significant differences in patterns of seasonal variations of CO2 and CH4 among the fertilizer and non-fertilizer treatments, but the seasonal patterns of N2O emission were significantly influenced by the exogenous nitrogen. Seasonal averages of the CO2 flux from non-fertilizer and fertilizer were 987.74 and 1,344.35 mg m −2 h −1, respectively, in 2004, and 898.59 and 2,154.17 mg m −2 h −1, respectively, in 2005. And the CH4 from the control and fertilizer treatments were 6.05 and 13.56 mg m −2 h −1 and 0.72 and 1.88 mg m −2 h −1, respectively, in 2004 and 2005. The difference of N2O flux between the fertilizer and non-fertilizer treatments is also significant either in 2004 and 2005. On the time scale of 20-, 100-, and 500-year periods, the integrated global warming potential (GWP) of CO2 + CH4 + N2O released during the two growing seasons for the treatment of fertilizer was 97, 94 and 89%, respectively, higher than that for the control, which suggested that the nitrogen fertilizer can enhance the GWP of the CH4 and N2O either in long time or short time scale.
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effects of exogenous nitrogen on Freshwater marsh plant growth and n2o fluxes in sanjiang plain northeast china
Atmospheric Environment, 2007Co-Authors: Lihua Zhang, Changchun Song, Dexuan Wang, Yiyong WangAbstract:Abstract Field management strongly affected the emission of N 2 O and plant growth from Freshwater Marshes. Nitrous oxide ( N 2 O ) fluxes, leaf area, plant height and above ground biomass were investigated under four N treatments (0, 6, 12 and 24 g NH 4 NO 3 – N m - 2 ) in the Freshwater Marshes of Sanjiang Plain, Northeast China. The average growing season N 2 O flux was 0.065 ± 0.037 , 0.086 ± 0.111 , 0.141 ± 0.186 , 0.445 ± 0.491 mg m - 2 h - 1 , respectively, the above-ground biomass was 201 ± 49 , 252 ± 40 , 290 ± 47 , 954 ± 115 g m - 2 , respectively, the plant height was 66.25 ± 20.99 , 71.91 ± 16.18 , 73.55 ± 16.59 , 84.14 ± 27.07 cm , respectively. Exogenous nitrogen had a significant impact on N 2 O fluxes and plant growth. Compared to the non-fertilization treatment, the average growing season N 2 O flux in fertilization increased by 32%, 113%, 581%, respectively, the above-ground biomass increased by 26%, 44%, 375%, respectively, while the plant height increased by 8.5%, 11% and 27%, respectively. A quadratic relationship between the nitrogen applied rate and N 2 O fluxes, and a non-linear positive correlation between the nitrogen and above-ground biomass were found, while the relationship between the N 2 O flux and the above-ground biomass was significantly linear positive correlated after nitrogen application, so was the plant height. It was proposed that the exogenous nitrogen gives rise to considerable N 2 O emissions from Freshwater Marshes and a large fraction of N 2 O was emitted to the atmosphere via the transpiration stream within the Deyeuxia angustifolia plants, which provides some quantificational data on the relationship between the nitrogen, N 2 O fluxes and marsh plant growth.
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annual dynamics of co2 ch4 n2o emissions from Freshwater Marshes and affected by nitrogen fertilization
Environmental Sciences, 2006Co-Authors: Changchun Song, Lihua Zhang, Yiyong Wang, Zhichun ZhaoAbstract:Annual dynamics of CO2, CH4, N2O emissions from Freshwater Marshes and affected by nitrogen fertilization were studied in situ in Sanjiang Plain of Northeast China from June 2002 to December 2004, using the static opaque chamber-GC techniques. The results showed that there was significant seasonal and annual variation in the CO2, CH4 and N2O emissions. The ecosystem emission of CO2 reached a maximum of 779.33- 965.40 mg x (mxh)(-1) in July and August, CH4 reached a maximum of 19.19-30.52 mg x (mxh)(-1) in August, N2O reached a maximum of 0.072-0.15 mgx (mxh)(-1) in May and September, respectively. While the minimum of the CO2, CH4, N2O emission was 2.36-18.73 mg x (mxh)(-1), - 0.35 - 0.59 mg x (mxh)(-1), - 0.032- 0.009 mg (mxh)(-1), respectively, which occurs in winter. The Freshwater marsh was the sink of N2O in winter. Temperature was a primary factor, controlling greenhouse gas seasonal emissions in Freshwater Marshes; while the precipitation and floodwater depth were the dominating influencing factors, affecting the greenhouse gas annual variations. Especially, the influence of precipitation on CH4 emissions was more obvious, comparing with the CO2 and N20 emissions. And the summer higher CH4 emission was mainly induced by the ice and snow thawing water in winter. Respiration of the ecosystem and CH4 emission were exponentially dependent on soil temperature of 5cm depth, while the N2O emission was not related to the soil temperature and water depth. The greenhouse gas (CO2, CH4, N2O) emissions were significantly influenced by nitrogen fertilization in Sanjiang Plain. The CO2, CH4, N2O flux of fertilization increased 34% , 145% , 110% , respectively, comparing to the control treatment.
