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1.
Environ Pollut ; 260: 114030, 2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-32004965

RESUMO

Temperate wetlands have been undergoing increased nitrogen (N) inputs in the past decades, yet its influence on dissolved organic carbon (DOC) dynamics is still elusive in these ecosystems. Here, using a field multi-level N addition (0, 6, 12, and 24 g N m-2 year-1) experiment, we investigated the changes in aboveground plant biomass, DOC production from plant litters, DOC biodegradation, and DOC concentration in surface water and soil pore water (0-15 cm depth) following 10 years of N addition in a freshwater marsh of Northeast China. We observed that, irrespective of N addition levels, N addition caused an increase in DOC production from plant litters under both non-flooded and flooded conditions. Conversely, DOC biodegradation was inhibited by N addition in both surface water and soil pore water. Because of enhanced DOC production from plant litters and declined DOC biodegradation, N addition elevated DOC concentration in surface water and soil pore water across the growing season. In addition, long-term N addition increased aboveground plant biomass, but decreased species richness. Our results suggest that long-term N enrichment promotes DOC accumulation through the contrasting effects on litter-derived DOC production and microbial decomposition of DOC in temperate wetlands.

2.
J Trace Elem Med Biol ; : 126433, 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31735605

RESUMO

BACKGROUND: Zn is an essential trace element for vertebrates, and Zn uptake and transport is related with the ZIP family of Zn transporters. Meantime, Zn also influenced the expression of ZIP family members. METHODS: We cloned and characterized the full-length cDNA sequences of ten Zn transport-relevant genes (ZIP1, ZIP3, ZIP6, ZIP7, ZIP8, ZIP9, ZIP10, ZIP11, ZIP13 and ZIP14) from yellow catfish Pelteobagrus fulvidraco, investigated their mRNA tissue expression. These ZIP mRNA expression was also assessed in the primary hepatocytes and intestinal epithelial cells of yellow catfish in response to three Zn levels (0, 30 µM and 60 µM, respectively). RESULTS: All these genes shared the similar domains with the corresponding members in mammals. The mRNA expression of the ten ZIP genes was detected in nine-tested tissues, but variable among these tissues. Flow cytometry analysis and confocal microscopy observation indicated that intracellular free Zn2+ concentration in hepatocytes and intestinal epithelial cells increased with increasing Zn incubation concentration at both 24 h and 48 h. Zn incubation differentially influenced mRNA levels of ZIP transporters in the hepatocytes and intestinal epithelial cells, in a time- and cells-dependent manners. In the hepatocytes, at 24 h, compared to the control, Zn addition down-regulated mRNA levels of ZIP1, ZIP3, ZIP6, ZIP7, ZIP8, ZIP9, ZIP11 and ZIP14; however, ZIP10 mRNA levels were lower in 60 µM Zn group than those in the control and 30 µM Zn group. At 48 h, mRNA levels of ZIP1, ZIP6, ZIP7, ZIP9, ZIP10 and ZIP14 declined with increasing Zn incubation concentrations; ZIP3 mRNA levels were the lowest in 60 µM Zn group and showed no significant differences between the control and 30 µM Zn group. In the intestinal epithelial cells, at 24 h, Zn addition down-regulated mRNA levels of ZIP1, ZIP6, ZIP7, ZIP8, ZIP9, ZIP10, ZIP11, ZIP13 and ZIP14; ZIP3 mRNA levels were lower in 60 µM Zn group than those in the control and 30 µM Zn group. At 48 h, Zn addition up-regulated mRNA levels of ZIP6 and ZIP9, but down-regulated mRNA levels of ZIP8, ZIP10 and ZIP13. ZIP7, ZIP11 and ZIP14 mRNA abundances were the lowest in 60 µM Zn group and showed no significant differences between the control and 30 µM Zn group. CONCLUSION: For the first time, our study characterized ten ZIP family members in yellow catfish, explored their mRNA tissue expression. Their regulation to Zn addition were also investigated in the hepatocytes and intestinal epithelial cells of yellow catfish. Our study revealed the mechanism of cells exposed to Zn addition and provided novel insights for the regulatory mechanism of Zn homeostasis.

3.
Sci Total Environ ; 605-606: 332-336, 2017 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-28668744

RESUMO

Phosphorus (P) enrichment is expected to strongly influence dissolved organic carbon (DOC) biodegradation. However, the relationship between P availability and DOC biodegradation is largely unknown in nitrogen (N)-limited ecosystems. Here, we investigated the changes in the ratio of DOC to dissolved total nitrogen (DTN), specific UV absorbance at 254nm (SUVA254), and DOC biodegradation in surface water and soil pore water (0-15cm depth) following eight years of multi-level P addition (0, 1.2, 4.8, and 9.6gPm-2year-1) in an N-limited freshwater marsh in Northeast China. We found that P addition caused an increase in DOC biodegradation in surface water and soil pore water, irrespective of the P addition levels. Compared with the control treatment, the P addition rates of 1.2, 4.8, and 9.6gPm-2year-1 increased DOC biodegradation by 20.7%, 15.2%, and 14.5% in surface waters, and 11.3%, 9.4%, and 12.0% in soil pore waters, respectively. The DOC biodegradation was separately negatively correlated with the DOC:DTN ratio and SUVA254, indicating that the positive effect of P addition on DOC biodegradation was caused by the elevated N concentration and the reduced DOC aromaticity. Our findings suggest that P enrichment enhances the biodegradability of DOC through increased N availability and altered DOC chemical composition, which would accelerate DOC loss from the waters and alter ecosystem C balance in N-limited temperate wetlands.

4.
Sci Total Environ ; 586: 1032-1037, 2017 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-28215795

RESUMO

Understanding how P enrichment alters the quantity and quality of dissolved organic carbon (DOC) is important, because of their role in regulating the C cycle. Here, we established a four-level P addition experiment (0, 1.2, 4.8, and 9.6gPm-2year-1) in a N-limited freshwater wetland in the Sanjiang Plain, Northeast China. The aim of this study was to examine the effects of eight years of P addition on DOC concentration, SUVA254 (Abs254/DOC concentration, indicating the aromaticity of DOC), C:C ratio (Abs400/DOC concentration, indicating the proportion of colored humic substances in DOC), and E4:E6 ratio (Abs465/Abs665, indicating the molecular size of humic substances) in surface water and soil pore water (0-15cm depth) during the growing season (June through September). Our results showed similar changing trends in concentration and optical properties of DOC following eight years of P addition in the both surface water and soil pore water across the sampling dates. Generally, P addition decreased DOC concentration, SUVA254, and C:C ratio, and increased E4:E6 ratio, irrespective of P addition levels. These altered optical properties of DOC indicated that P addition decreased the molecular weight and aromaticity of DOC, and thus increased the quality of DOC. These results suggest P enrichment substantially reduces the quantity of DOC in N-limited temperate freshwater wetlands, and imply that increased DOC quality following P addition can further provide a positive feedback to decreased DOC pool.

5.
Sci Total Environ ; 559: 1-6, 2016 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-27045368

RESUMO

Phosphorus (P) enrichment induced by anthropogenic activities results in modified plant nutrient status, which potentially alters the stoichiometry of carbon (C), nitrogen (N), and P in plants. However, how increased P availability changes plant C:N:P stoichiometry at different hierarchical scales is unclear in N-limited ecosystems. In this study, we conducted a four-level P addition experiment (0, 1.2, 4.8, and 9.6gPm(-)(2)year(-1)) to elucidate the effect of P enrichment on plant C:N:P stoichiometric ratios at both the species and community levels in a freshwater wetland in the Sanjiang Plain, Northeast China. We found that species- and community-level plant C:N:P stoichiometry responded consistently to six years of P addition, although there was a shift in species dominance. Phosphorus addition increased plant N and P concentrations and thus decreased C:N, C:P, and N:P ratios irrespective of the P addition levels. These similar change trends at different scales resulted from the identical responses of plant N and P concentrations in different species to P addition. Moreover, plant N concentration exhibited an increasing trend with increasing P addition levels, whereas plant C:N ratio showed a declining trend. At the community level, P addition at the rates of 1.2, 4.8, and 9.6gPm(-2)year(-1) decreased the C:N ratio by 24%, 27%, and 34%; decreased the C:P ratio by 33%, 35%, and 38%; and decreased the N:P ratio by 12%, 10%, and 6%, respectively. Our results indicate that the stoichiometric responses to P addition are scale-independent, and suggest that altered plant C:N:P stoichiometry induced by P enrichment would stimulate organic matter decomposition and accelerate nutrient cycles in N-limited temperate freshwater wetlands.

6.
Sci Rep ; 5: 8097, 2015 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-25631373

RESUMO

Anthropogenic activities have increased phosphorus (P) inputs to most aquatic and terrestrial ecosystems. However, the relationship between plant nutrient resorption and P availability is still unclear, and much less is known about the underlying mechanisms. Here, we used a multi-level P addition experiment (0, 1.2, 4.8, and 9.6 g P m(-2) year(-1)) to assess the effect of P enrichment on nutrient resorption at plant organ, species, and community levels in a freshwater marsh of Northeast China. The response of nutrient resorption to P addition generally did not vary with addition rates. Moreover, nutrient resorption exhibited similar responses to P addition across the three hierarchical levels. Specifically, P addition decreased nitrogen (N) resorption proficiency, P resorption efficiency and proficiency, but did not impact N resorption efficiency. In addition, P resorption efficiency and proficiency were linearly related to the ratio of inorganic P to organic P and organic P fraction in mature plant organs, respectively. Our findings suggest that the allocation pattern of plant P between inorganic and organic P fractions is an underlying mechanism controlling P resorption processes, and that P enrichment could strongly influence plant-mediated biogeochemical cycles through altered nutrient resorption in the freshwater wetlands of Northeast China.


Assuntos
Água Doce , Nitrogênio/metabolismo , Fósforo/farmacologia , Plantas/metabolismo , Áreas Alagadas , Biomassa , China , Ecossistema , Especificidade de Órgãos/efeitos dos fármacos , Plantas/efeitos dos fármacos , Especificidade da Espécie
7.
Huan Jing Ke Xue ; 32(1): 290-7, 2011 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-21404701

RESUMO

The experiment was carried in Sanjiang Plain in the northeast of China during the growing season in 2009. Soil organic carbon (SOC), as well as the soil active organic carbon fractions in the 0-20 cm soil layer of Calamagrostis angustifolia wetland under different water conditions were on monthly observation. Based on the research and indoor analysis, the seasonal dynamics of light fractions of soil organic carbon (LFOC) and microbial biomass carbon (MBC) were analyzed. The results indicated that the SOC contents had significantly seasonal dynamics, and the hydrological circle had apparently driving effect on LFOC and MBC during the growing season, especially under the seasonal flooded condition. The freeze-thaw process reduced the SOC, LFOC, MBC contents, with the decreases of 74.53%, 80.93%, 83.09%, while both carbon contents of light and heavy fractions were reduced at the same time. The result also showed that the seasonal flooding condition increased the proportion of LFOC in topsoil, which was larger in marsh meadow (13.58%) than in wet meadow (11.96%), whilst the MBC in marsh meadow (1 397.21 mg x kg(-1)) was less than the latter (1 603.65 mg x kg(-1)), proving that the inundated environment inhibited the mineralization and decomposition of organic matter. But the microbial activity could be adaptive to the flooding condition. During the growing season the MBC soared to 1 829.21 mg x kg(-1) from 337.56 mg x kg(-1) in July, and the microbial quotient was 1.51 times higher than that in June, indicating the high microbial efficacy of soil organic matter. Meanwhile, there was a significant correlation between the contents of LFOC and SOC (r = 0.816), suggesting that higher LFOC content was favorable to the soil carbon accumulation. Moreover, in the seasonal flooded Calamagrostis angustifolia wetland the soil LFOC content was significantly correlated with MBC (r = 0.95), implying that the available carbon source had more severe restriction on the microbial activity under the flooding environment.


Assuntos
Carbono/química , Compostos Orgânicos/química , Poaceae/metabolismo , Solo/química , Áreas Alagadas , China , Compostos Orgânicos/análise , Poaceae/classificação , Poaceae/crescimento & desenvolvimento , Estações do Ano , Solo/análise , Água/análise
8.
Huan Jing Ke Xue ; 31(4): 833-42, 2010 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-20527159

RESUMO

Extensive reclamation of marshland into cropland has had tremendous effects on the ecological environment in the Sanjiang Plain. Observations over marshland, rice paddy and soybean field were made with eddy covariance measuring systems from May to October in 2005, 2006 and 2007. The objective of this study was to identify the effects of the conversion of marshland to cropland on evapotranspiration in the Sanjiang Plain. The results showed that the diurnal variation curves of latent heat flux were single peaked in marshland, rice paddy and soybean field. The daily maximum latent heat flux increased by 14%-130% in rice paddy in the three measuring years, however, in soybean field, it increased by 3%-77% in 2006 but decreased by 25%-40% in 2005 and 2007 by comparison with that in marshland. This difference was due to the change of leaf area index when marshland was reclaimed into cropland. Seasonal change of latent heat flux was identical for the three land use types. Daily averaged latent heat flux of rice paddy, from May to October, showed 38%-53% increase compared with that of marshland, which resulted from the increase in net radiation and leaf area index. When marshland was reclaimed into soybean field, the variation of daily averaged latent heat flux depended primarily on precipitation. Precipitation was the main factor that controlled evapotranspiration over soybean field which was usually in condition of soil water deficit. Drought caused 11%-17% decrease of daily averaged latent heat flux over soybean field in 2005 and 2007, while sufficient precipitation caused 22% increase in 2006, comparing to marshland. Similarly, during the growing season from June to September, total evapotranspiration of rice paddy increased by 24%-51% compared with that of marshland, and the total evapotranspiration of soybean field decreased by 19%-23% in 2005 and 2007 and increased by 19% in 2006. It is concluded that the evapotranspiration changes significantly when the marshland was reclaimed into rice paddy or soybean field in the Sanjiang Plain. Compared to marshland, the evapotranspiration is higher in rice paddy and soybean filed with sufficient precipitation, while lower in soybean field under drought. These changes are found to be highly related to the variations of net radiation, leaf area index and precipitation.


Assuntos
Produtos Agrícolas/fisiologia , Transpiração Vegetal/fisiologia , Água/análise , Áreas Alagadas , China , Produtos Agrícolas/crescimento & desenvolvimento , Monitoramento Ambiental , Oryza/crescimento & desenvolvimento , Oryza/fisiologia , Chuva , Solo/análise , Soja/crescimento & desenvolvimento , Soja/fisiologia
9.
Huan Jing Ke Xue ; 31(2): 444-9, 2010 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-20391716

RESUMO

Plant aboveground biomass, total organic carbon( TOC), microbial biomass carbon( MBC), basal respiration( BR), microbial quotient (Cmic/Corg) and metabolic quotient (qCO2) in 0-15 cm and 15-50 cm marsh soil of Calamagrostis angustifolia under different water levels were investigated with controlled experiment. The result showed that water level exerted significant effect on plant biomass, which was the highest under 10 cm waterlogged level and of higher productivity under 0-20 cm waterlogged level. TOC, MBC, BR, Cmic/Corg and qCO2 differed significantly under different water levels. BR and TOC responded to different waterlogged levels in the same way. BR and TOC of 0-15 cm marsh soil were the highest under 0 cm waterlogged level, however, BR and TOC of 15-50 cm marsh soil decreased respectively with increasing water, which was corresponding with soil MBC and Cmic/Corg and qCO2 increased with increasing water. As a result, microbial community is altered and microbial activity is decreasing by increasing waterlogged level, and microbial activity is the lowest under 30 cm waterlogged level, which affects organic carbon accumulation and decomposition.


Assuntos
Biomassa , Poaceae/metabolismo , Microbiologia do Solo , Água/análise , Áreas Alagadas , Carbono/análise , China , Poaceae/classificação , Poaceae/crescimento & desenvolvimento , Solo/análise
10.
Huan Jing Ke Xue ; 30(11): 3130-5, 2009 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-20063718

RESUMO

By the soil respiration system of Li-6400, the characteristics of soil respiration with and without litter were investigated to explore the litter's contributions to soil respiration and its correlations with the input of litter and environmental factors under different land-use types in Sanjiang Plain. Results demonstrated that the average contribution of litter to soil respiration ranged from - 0.21 to 0.64 micromol/(m2 x s) in the growing season under the four land-use types. The contribution rate showed in the following order: wetland (14%) > artificial forest (12%) > soybean field (8%) > abandoned land (- 5%). As to abandoned land, the value was negative, and the litter inhibited soil respiration. The litter' s contributions to soil respiration may depend on the balance between the decomposition of litter and its shielding effects on soil respiration. There were highly significant correlations between litter's contributions to soil respiration and soil temperature at 10cm depth except for soybean field. Moreover, the influence of rainfall associated with the input of litter, which suggested that besides decomposition litter may take part in the ecological effect of climate changes in the future.


Assuntos
Dióxido de Carbono/análise , Solo/análise , Soja/crescimento & desenvolvimento , Árvores/genética , Áreas Alagadas , China , Monitoramento Ambiental , Folhas de Planta/metabolismo , Chuva , Temperatura Ambiente
11.
Ying Yong Sheng Tai Xue Bao ; 19(9): 1925-30, 2008 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-19102304

RESUMO

Eddy covariance technique was adopted in measuring the evapotranspiration (ET) from a typical marsh in Sanjiang Plain in the growth season (May to September) of 2006. After analyzing the seasonal variation of the ET, the daily ET from the marsh was estimated by using Penman-Monteith (PM) and Priestley-Taylor (PT) models, and the estimated values were tested by the measured values. The results showed that the ET from the marsh had an obvious seasonal variation, with the lowest month-average daily ET in May and the highest one in July. The average daily ET in growth season was 1.94 mm x d(-1), and the total ET was 293 mm. The daily ET estimated by PM model was significantly lower than the measured one during the early and late growth seasons. A good match was observed between PT-estimated values and measured values throughout the growth season. Considering its accuracy and simplicity, PT model was more suitable for the simulation of marsh ET.


Assuntos
Ecossistema , Transpiração Vegetal , Poaceae/fisiologia , Áreas Alagadas , China , Monitoramento Ambiental , Modelos Teóricos , Volatilização , Movimentos da Água
12.
Huan Jing Ke Xue ; 29(5): 1380-7, 2008 May.
Artigo em Chinês | MEDLINE | ID: mdl-18624211

RESUMO

The changes in microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) were examined in order to assess the effect of surface layer soil (0 - 10 cm) under different land-use types after freshwater marshes tillage in the Sanjiang Plain Northeast China. Land uses were Deyeuxia angustifolia freshwater marshes ((DAM), cultivated land (CL), recovery freshwater marsh (RFM), constructed woodland (CW). After DAM soil tillage, MBC, MBN, DOC and DON declined strongly in agricultural surface soil layer, decreased 63.8%-80.5% (MBC), 56.3%-67.1% (MBN), 43.1%-44.3% (DOC) and 25.2%-56.1% (DON) respectively. In contrast, these C, N fraction had significant recovered in RFM and CW surface soil, increased 36.1%-59.9% (MBC), 46.7%-65.9% (MBN), 67.0%-69.3% (DOC)and 81.2%-88.3% (DON) respectively. Cultivation and land-use affected soil MBC, MBN, DOC and DON intensely. Therefore these labile C, N fractions have the significant relative under different land-use types. However DOC was more obvious controlled than DON by the land-use types. The relative between DOC and MBC, MBN have much difference than DON, the main reason of this distinction is the diverse source in available carbon and nitrogen that taken by microbial property under different land uses.


Assuntos
Carbono/análise , Água Doce/análise , Nitrogênio/análise , Microbiologia do Solo , Áreas Alagadas , Biomassa , Ecossistema , Água Doce/microbiologia , Poaceae/crescimento & desenvolvimento , Solo/análise , Soja/crescimento & desenvolvimento , Árvores/crescimento & desenvolvimento
13.
Ying Yong Sheng Tai Xue Bao ; 19(2): 285-9, 2008 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-18464633

RESUMO

With closed chamber and GC technique, a comparative study was conducted on the CO2 fluxes in mire and grassland on Ruoergai plateau during the plant growth period in 2003-2005. The results showed that the mean value of the CO2 fluxes in the three years was 203.22 mg x m(-2) x h(-1) in mire and 323.03 mg x m(-2) x h(-1) in grassland, with the former being only about 60% of the latter. The perennially water-logging of mire limited the decomposition of plant residues, roots and organic substances, resulting in a lower CO2 flux in mire than in grassland. The seasonal changes of CO2 fluxes in mire and grassland were positively correlated with air temperature, the peak value being usually appeared in July or August, and the diurnal changes of the CO2 fluxes were also positively correlated with air temperature, the peak value being usually appeared between 11:00 and 17:00. The CO2 fluxes had a higher correlation with the soil temperature at the depth of 5 cm than at the depths of 10 cm and 15 cm.


Assuntos
Dióxido de Carbono/análise , Monitoramento Ambiental/métodos , Poaceae/crescimento & desenvolvimento , Solo/análise , Áreas Alagadas , China , Estações do Ano , Temperatura Ambiente
14.
Ying Yong Sheng Tai Xue Bao ; 19(10): 2194-200, 2008 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-19123355

RESUMO

With seedling's transplanting experiment under different water levels, this paper studied the growth responses of belowground modules of Carex lasiocarpa to various water regimes and water experiences in Sanjiang Plain. The results showed that the belowground modules of C. lasiocarpa had significantly different responses to water regimes. At thriving stage, the length of rhizome and adventitious root decreased with increasing water level, and until later growth stage, the maximal value still appeared under drought condition. However, under dry-wet alternate condition, the length of rhizome and adventitious root increased most from thriving stage to the end, indicating that stable and lower water level could improve the growth of rhizome and adventitious root. The biomass of rhizome, adventitious root, and belowground part were maximal under dry-wet alternate condition at both growth stages. For those with different water experiences, the ones undergoing alternate condition in early growth season and then drought had maximal rhizome biomass, and the others under sustained alternate condition had maximal adventitious root and belowground biomass. More biomass was distributed to rhizome in the later growth season under various water regimes. The percentage of rhizome in total biomass was significantly higher under drought condition than under other water conditions through the growth season. Besides, C. lasiocarpa grew slowly when submerged, but could recover through rhizomatic reproduction after the stress disappeared.


Assuntos
Carex (Planta)/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Plântula/crescimento & desenvolvimento , Água/metabolismo , Biomassa , China
15.
Ying Yong Sheng Tai Xue Bao ; 19(12): 2599-604, 2008 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-19288710

RESUMO

Taking the typical marsh wetland plant Calamagrostis angustifolia in Sanjiang Plain of Northeast China as test material, a field control experiment was conducted to study its leaf morphological characters, chlorophyll content, and aboveground biomass under effects of different levels of exogenous nitrogen input in 2004-2007. Four nitrogen (N) fertilization treatments, i.e., 0 (CK), 6 g x m(-2) x a(-1) (N6), 12 g x m(-2) x a(-1) (N12) and 24 g x m(-2) x a(-1) (N24), were installed. The results showed that there were no significant differences in the leaf length and width among different N fertilization treatments, but the specific leaf area was the smallest (149.54 +/- 18.27 cm2 x g(-1)) under N12, which indicated that the leaves of C. angustifolia were thicker under this N treatment. The leaf chlorophyll content showed a unimodal distribution over the growth season, which increased with the amount of N input before the peak. The peak occurred earlier under N12 and N24 than under N6 and CK. After the peak, the chlorophyll content declined sharply under N24 but slowly under N6, indicating that moderate N input could delay leaf senescence. Continuous high N (N24) input might advance plant growth, while leaf senescence would occur earlier. By the end of growth season both in 2005 and in 2007, the aboveground biomass of C. angustifolia increased with increasing N input, but declined by 53.72% after 4 years continuous high N (N24) input (in 2007), compared with that after 2 years treatment (in 2005).


Assuntos
Clorofila/análise , Nitrogênio/farmacologia , Folhas de Planta/anatomia & histologia , Poaceae/crescimento & desenvolvimento , Áreas Alagadas , Biomassa , China , Folhas de Planta/química , Poaceae/efeitos dos fármacos , Poaceae/metabolismo
16.
Huan Jing Ke Xue ; 29(12): 3525-30, 2008 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-19256396

RESUMO

By laboratory incubation experiment, under aerobic and submerged soil moisture conditions, we investigated the mineralization of soil organic carbon (SOC) and contents of dissolved organic carbon (DOC) with different nitrogen inputs in a freshwater marsh soil. The results showed that under aerobic condition, there were no significant effects on the mineralization of SOC and contents of DOC as the net nitrogen input was 1 mg x g(-1) (N1), however, they were significantly higher than control and N1 treatments when nitrogen input increased to 2 and 5 mg x g(-1) (N2, N3), and the amount of DOC was respectively 187.22% and 203.25% higher than control (250.62 mg x kg(-1)). Under submerged condition, all N treatments restrained the mineralization of SOC, and the content of DOC was respectively 88.34% (N1), 82.69% (N2) and 80.04% (N3) lower than control (642.52 mg x kg(-1)). There were significant positive correlations between the contents of DOC and the amounts of cumulative C by mineralization (R2 was 0.939 and 0.843, respectively), which suggested that the changes of DOC affected by N input might be one of the important reasons that arose the differences of SOC mineralization. The results also indicate that as the waterlogged environment disappeared in wetland, the supply of exogenous nitrogen might bring large loss of SOC through enhancing the mineralization of SOC and leaching of DOC.


Assuntos
Carbono/análise , Nitrogênio/química , Compostos Orgânicos/análise , Áreas Alagadas , Amônia/química , Biodegradação Ambiental , Carbono/química , China , Ecossistema , Compostos Orgânicos/química
17.
Huan Jing Ke Xue ; 28(9): 1905-11, 2007 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-17990529

RESUMO

A model was developed based on the theories of physiological ecology and turnover dynamics of organic carbon in wetland ecosystem. It aimed to illustrate the process and characteristics of carbon cycling and its potential changes under climate change scenarios in wetland ecosystems. The key environmental parameters to determine the effects of temperature, water-logging, and freeze-thaw were gained from the results of incubation experiments. Effects of CO2 fertilizing on the carbon sequestration and plant cover on organic carbon mineralization were also taken into account in this model. It was verified by the conventional observed meteorologic data in temperate and subtropical wetland ecosystems. Sensitivity analysis and prediction under climate change scenarios by this model were also discussed. There were significant correlations between the simulated and observed values of sediment respiration in temperate wetlands in Northeast China. It was estimated that the annual net carbon sequestration rate was about 104 g x m(-2) in permanently water-logged wetland ecosystems and 76 g x m(-2) in the seasonally water logged ones in temperate northeast China. The simulated value of the accumulated organic carbon density was within the changing range of the investigated data. The model was sensitive to the change of parameters of CO2 concentration and temperature. The potential changes in carbon cycling characteristics were also predicted under assumed climate change scenarios of A1B and A1FI. It indicated that the exchange of carbon between the atmosphere and the wetland ecosystem became more active under climate change scenario of warming and increased CO2 concentration assuming no changing of hydrological condition. The net primary production (NPP) and the organic carbon density in temperate wetland ecosystems would increase under the scenario of doubled CO2 concentration and less than 2.5 degrees C increment of temperature. In this case wetland ecosystem would act as a net carbon sink of the atmosphere. However, it had no advantage to the carbon sequestration and accumulation in wetland ecosystems under the more warming scenarios. Under these more warming scenarios, the amount of increased NPP resulted from CO2 fertilizing and warming could not compensate the carbon loss from the accelerated respiration caused by warming. The organic carbon accumulated in seasonally water-logged wetland even would decrease under the assumed scenarios.


Assuntos
Dióxido de Carbono/química , Carbono/metabolismo , Ecossistema , Modelos Teóricos , Áreas Alagadas , Clima , Conservação dos Recursos Naturais , Sedimentos Geológicos/química , Compostos Orgânicos/metabolismo , Plantas/metabolismo , Estações do Ano
18.
Huan Jing Ke Xue ; 28(8): 1854-60, 2007 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-17926423

RESUMO

Measurements of nocturnal ecosystem respiration were conducted in a rice paddy of Sanjiang from July to September in 2004 and in a soybean field from June to September in 2005, using eddy covariance (EC) and dark chamber-gas chromatography (DC-GC). The differences of simultaneous data measured by two methods were not significant when night turbulent mixing was well. The correlations between two methods can be improved under more large friction velocity. EC measurements were poorly correlated to night ecosystem respiration estimated by chamber models for the variability inherent to EC measurements (R2 = 0.06, 0.23 for rice and soybean, respectively). However, this correlation can be improved by aggregating measurements over longer time period (R2 = 0.16, 0.75 for rice and soybean field, respectively). In general, whatever comparison with simultaneous chamber measurements or modeled results, eddy covariance measurements were consistently lower 4% - 30% than chambers, and this bias varied with crop growing stage, which were maximum in middle and minimum in early and late growing stage.


Assuntos
Dióxido de Carbono/análise , Ecossistema , Oryza/metabolismo , Soja/metabolismo , Respiração Celular/fisiologia , China , Cromatografia Gasosa/métodos , Ritmo Circadiano/fisiologia , Modelos Biológicos , Oryza/crescimento & desenvolvimento , Consumo de Oxigênio/fisiologia , Fotossíntese/fisiologia , Transpiração Vegetal/fisiologia , Soja/crescimento & desenvolvimento
19.
Ying Yong Sheng Tai Xue Bao ; 18(4): 783-7, 2007 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-17615872

RESUMO

Based on field investigation and by using Levins formulae, the niche breadth and niche overlap of dominant plant populations in Sanjiang Plain marsh wetland were studied. The results showed that the niche breadth of test marsh wetland plants decreased in the order of Carex pseudocuraica (0.907) > C. lasiocarpa (0.864) > Glyceria spiculosa (0.855) > Deyeuxia angustifolia (0.500) = Menyanthes trifotiata (0.500) = Naumburgia thyrsiflora (0.500) = Anemone dichotoma (0.500). The niche overlaps among C. lasiocarpa, C. pseudocuraica, M. trifotiata and N. thyrsiflora, and among G. spiculosa, D. angustifolia and A. dichotom were comparatively large, indicating an intense competition among them, while the niche overlap between M. trifotiata and N. thyrsiflora, and D. angustifolia and A. dichotoma was 0, suggesting their different manner of environmental adaptation. Soil water was the dominating environmental factor of wetland plant ecological adaptability. The niche fitness of plant to environment depended on the combined effect of soil water and nutrients. The niche characteristics of marsh wetland plants could better indicate their ecological adaptability and distribution range.


Assuntos
Carex (Planta)/crescimento & desenvolvimento , Cyperaceae/crescimento & desenvolvimento , Ecossistema , Poaceae/crescimento & desenvolvimento , Áreas Alagadas , Adaptação Fisiológica , China , Água Doce , Desenvolvimento Vegetal , Dinâmica Populacional , Especificidade da Espécie
20.
Ying Yong Sheng Tai Xue Bao ; 18(11): 2432-7, 2007 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-18260443

RESUMO

With simulation test, this paper studied the effects of water level on the rhizomati germination and growth of Calamagrostis angustifolia and Carex lasiocarpa, the two typical wetland plants in Sanjiang Plain. The results showed that these two plants had different responses to water level. The population density, mean height, and maximum height of C. angustifolia reached the peak at 0 cm water level; while the mean and maximum height of C. lasiocarpa increased, but its population density decreased with increasing water level. At the early stage of germination, definite duration without inundation promoted the rhizomatic germination of these two plants, while continuous inundation constrained it. During growth period, excess inundation limited the growth of C. angustifolia, but C. lasiocarpa grew better under deeper water. Drought constrained the growth of C. angustifolia and C. lasiocarpa, and possibly, changed their life history.


Assuntos
Ecossistema , Raízes de Plantas/crescimento & desenvolvimento , Poaceae/crescimento & desenvolvimento , Água/análise , Áreas Alagadas , Carex (Planta)/crescimento & desenvolvimento , China , Solo/análise , Especificidade da Espécie
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