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Sample records for affect soil respiration

  1. Effect of biosolid waste compost on soil respiration in salt-affected soils

    NASA Astrophysics Data System (ADS)

    Raya, Silvia; Gómez, Ignacio; García, Fuensanta; Navarro, José; Jordán, Manuel Miguel; Belén Almendro, María; Martín Soriano, José

    2013-04-01

    A great part of mediterranean soils are affected by salinization. This is an important problem in semiarid areas increased by the use of low quality waters, the induced salinization due to high phreatic levels and adverse climatology. Salinization affects 25% of irrigated agriculture, producing important losses on the crops. In this situation, the application of organic matter to the soil is one of the possible solutions to improve their quality. The main objective of this research was to asses the relation between the salinity level (electrical conductivity, EC) in the soil and the response of microbial activity (soil respiration rate) after compost addition. The study was conducted for a year. Soil samples were collected near to an agricultural area in Crevillente and Elche, "El Hondo" Natural Park (Comunidad de Regantes from San Felipe Neri). The experiment was developed to determine and quantify the soil respiration rate in 8 different soils differing in salinity. The assay was done in close pots -in greenhouse conditions- containing soil mixed with different doses of sewage sludge compost (2, 4 and 6%) besides the control. They were maintained at 60% of water holding capacity (WHC). Soil samples were analyzed every four months for a year. The equipment used to estimate the soil respiration was a Bac-Trac and CO2 emitted by the soil biota was measured and quantified by electrical impedance changes. It was observed that the respiration rate increases as the proportion of compost added to each sample increases as well. The EC was incremented in each sampling period from the beginning of the experiment, probably due to the fact that soils were in pots and lixiviation was prevented, so the salts couldńt be lost from soil. Over time the compost has been degraded and, it was more susceptible to be mineralized. Salts were accumulated in the soil. Also it was observed a decrease of microbial activity with the increase of salinity in the soil. Keywords: soil

  2. Different tree species affect soil respiration spatial distribution in a subtropical forest of southern Taiwan

    NASA Astrophysics Data System (ADS)

    Chiang, Po-Neng; Yu, Jui-Chu; Wang, Ya-nan; Lai, Yen-Jen

    2014-05-01

    Global forests contain 69% of total carbon stored in forest soil and litter. But the carbon storage ability and release rate of warming gases of forest soil also affect global climate change. Soil carbon cycling processes are paid much attention by ecological scientists and policy makers because of the possibility of carbon being stored in soil via land use management. Soil respiration contributed large part of terrestrial carbon flux, but the relationship of soil respiration and climate change was still obscurity. Most of soil respiration researches focus on template and tropical area, little was known that in subtropical area. Afforestation is one of solutions to mitigate CO2 increase and to sequestrate CO2 in tree and soil. Therefore, the objective of this study is to clarify the relationship of tree species and soil respiration distribution in subtropical broad-leaves plantation in southern Taiwan. The research site located on southern Taiwan was sugarcane farm before 2002. The sugarcane was removed and fourteen broadleaved tree species were planted in 2002-2005. Sixteen plots (250m*250m) were set on 1 km2 area, each plot contained 4 subplots (170m2). The forest biomass (i.e. tree height, DBH) understory biomass, litter, and soil C were measured and analyzed at 2011 to 2012. Soil respiration measurement was sampled in each subplot in each month. The soil belongs to Entisol with over 60% of sandstone. The soil pH is 5.5 with low base cations because of high sand percentage. Soil carbon storage showed significantly negative relationship with soil bulk density (p<0.001) in research site. The differences of distribution of live tree C pool among 16 plots were affected by growth characteristic of tree species. Data showed that the accumulation amount of litterfall was highest in December to February and lowest in June. Different tree species planted in 16 plots, resulting in high spatial variation of litterfall amount. It also affected total amount of litterfall

  3. Roots affect the response of heterotrophic soil respiration to temperature in tussock grass microcosms

    PubMed Central

    Graham, Scott L.; Millard, Peter; Hunt, John E.; Rogers, Graeme N. D.; Whitehead, David

    2012-01-01

    Aims and Background While the temperature response of soil respiration (RS) has been well studied, the partitioning of heterotrophic respiration (RH) by soil microbes from autotrophic respiration (RA) by roots, known to have distinct temperature sensitivities, has been problematic. Further complexity stems from the presence of roots affecting RH, the rhizosphere priming effect. In this study the short-term temperature responses of RA and RH in relation to rhizosphere priming are investigated. Methods Temperature responses of RA, RH and rhizosphere priming were assessed in microcosms of Poa cita using a natural abundance δ13C discrimination approach. Results The temperature response of RS was found to be regulated primarily by RA, which accounted for 70 % of total soil respiration. Heterotrophic respiration was less sensitive to temperature in the presence of plant roots, resulting in negative priming effects with increasing temperature. Conclusions The results emphasize the importance of roots in regulating the temperature response of RS, and a framework is presented for further investigation into temperature effects on heterotrophic respiration and rhizosphere priming, which could be applied to other soil and vegetation types to improve models of soil carbon turnover. PMID:22492330

  4. Vegetation affects the relative abundances of dominant soil bacterial taxa and soil respiration rates in an upland grassland soil.

    PubMed

    Thomson, Bruce C; Ostle, Nick; McNamara, Niall; Bailey, Mark J; Whiteley, Andrew S; Griffiths, Robert I

    2010-02-01

    Plant-derived organic matter inputs are thought to be a key driver of soil bacterial community composition and associated soil processes. We sought to investigate the role of acid grassland vegetation on soil bacterial community structure by assessing bacterial diversity in combination with other soil variables in temporally and spatially distinct samples taken from a field-based plant removal experiment. Removal of aboveground vegetation resulted in reproducible differences in soil properties, soil respiration and bacterial diversity. Vegetated soils had significantly increased carbon and nitrogen concentrations and exhibited higher rates of respiration. Molecular analyses revealed that the soils were broadly dominated by Alphaproteobacterial and Acidobacterial lineages, with increased abundances of Alphaproteobacteria in vegetated soils and more Acidobacteria in bare soils. This field-based study contributes to a growing body of evidence documenting the effect of soil nutrient status on the relative abundances of dominant soil bacterial taxa, with Proteobacterial taxa dominating over Acidobacteria in soils exhibiting higher rates of C turnover. Furthermore, we highlight the role of aboveground vegetation in mediating this effect by demonstrating that plant removal can alter the relative abundances of dominant soil taxa with concomitant changes in soil CO(2)-C efflux.

  5. Quantifying the timescales over which exogenous and endogenous conditions affect soil respiration.

    PubMed

    Barron-Gafford, Greg A; Cable, Jessica M; Bentley, Lisa Patrick; Scott, Russell L; Huxman, Travis E; Jenerette, G Darrel; Ogle, Kiona

    2014-04-01

    Understanding how exogenous and endogenous factors and above-ground-below-ground linkages modulate carbon dynamics is difficult because of the influences of antecedent conditions. For example, there are variable lags between above-ground assimilation and below-ground efflux, and the duration of antecedent periods are often arbitrarily assigned. Nonetheless, developing models linking above- and below-ground processes is crucial for estimating current and future carbon dynamics. We collected data on leaf-level photosynthesis (Asat ) and soil respiration (Rsoil ) in different microhabitats (under shrubs vs under bunchgrasses) in the Sonoran Desert. We evaluated timescales over which endogenous and exogenous factors control Rsoil by analyzing data in the context of a semimechanistic temperature-response model of Rsoil that incorporated effects of antecedent exogenous (soil water) and endogenous (Asat ) conditions. For both microhabitats, antecedent soil water and Asat significantly affected Rsoil , but Rsoil under shrubs was more sensitive to Asat than that under bunchgrasses. Photosynthetic rates 1 and 3 d before the Rsoil measurement were most important in determining current-day Rsoil under bunchgrasses and shrubs, respectively, indicating a significant lag effect. Endogenous and exogenous controls are critical drivers of Rsoil , but the relative importance and the timescale over which each factor affects Rsoil depends on above-ground vegetation and ecosystem structure characteristics.

  6. Does photosynthesis affect grassland soil-respired CO2 and its carbon isotope composition on a diurnal timescale?

    PubMed Central

    Bahn, Michael; Schmitt, Michael; Siegwolf, Rolf; Richter, Andreas; Brüggemann, Nicolas

    2010-01-01

    Summary Soil respiration is the largest flux of carbon (C) from terrestrial ecosystems to the atmosphere. Here, we tested the hypothesis that photosynthesis affects the diurnal pattern of grassland soil-respired CO2 and its C isotope composition (δ13CSR). A combined shading and pulse-labelling experiment was carried out in a mountain grassland. δ13CSR was monitored at a high time resolution with a tunable diode laser absorption spectrometer. In unlabelled plots a diurnal pattern of δ13CSR was observed, which was not explained by soil temperature, moisture or flux rates and contained a component that was also independent of assimilate supply. In labelled plots δ13CSR reflected a rapid transfer and respiratory use of freshly plant-assimilated C and a diurnal shift in the predominant respiratory C source from recent (i.e. at least 1 d old) to fresh (i.e. photoassimilates produced on the same day). We conclude that in grasslands the plant-derived substrates used for soil respiratory processes vary during the day, and that photosynthesis provides an important and immediate C source. These findings indicate a tight coupling in the plant–soil system and the importance of plant metabolism for soil CO2 fluxes. PMID:19220762

  7. Altered Seasonality and Magnitude of Rainfall Affects Soil Respiration and Nitrous Oxide Fluxes in California Annual Grassland

    NASA Astrophysics Data System (ADS)

    Chou, W. W.; Silver, W. L.; Jackson, R. D.; Allen-Diaz, B.

    2004-12-01

    Currently, climate models do not agree on how rising concentrations of CO2 and other greenhouse gases will affect rainfall in California. Changes in moisture regime will likely alter rates of carbon (C) loss via soil respiration, as well as fluxes of N2O. Moisture availability can also affect plant productivity in highly seasonal environments. We examined the consequences of wetter conditions in an annual grassland in the Sierra foothills of northern California by extending the duration of the wet season by about 5 weeks and augmenting total annual rainfall by approximately 50 %. Discrete wet-up events took place prior to the onset of natural rains (early October 2003) and early in the drought period (May 2004). Soil respiration, N2O and CH4 effluxes, N mineralization, and above- and belowground plant production were measured in treatment and control plots over a one-year period. Soil CO2 fluxes for the first treatment year, though large, were not statistically different between wet and control plots (1078 \\pm148 g C m-2 and 1006 \\pm138 g C m-2, respectively). The combined wet-up events comprised 17 % of the soil respiration over the 12-month period in treated plots, about twice as much C released by control plots during the same time interval. Aboveground biomass was similar between wetted and control plots (415 \\pm45 g m-2 y-1 and 374 \\pm36 g m-2 y-1, respectively), while root biomass increased significantly with wetting during the first year of treatment (179 \\pm23 g m-2 y-1 and 111 \\pm13 g m-2 y-1 for treatment and control plots, respectively). The additional biomass C gained in treatment plots (53 g C m-2) partly offset the greater losses from respired C observed in treatment plots (72 g C m-2). Nitrous oxide emissions were low to negligible during the year with the exception of the time directly following wet-up, when N2O emissions averaged over 78\\pm13 ng N cm-2 h-1. Our first year of water manipulation in annual grasslands suggests that increased

  8. Soil Respiration - A Geochemist's Perspective

    NASA Astrophysics Data System (ADS)

    Van Cappellen, P.

    2015-12-01

    Soil biogeochemistry is largely driven by the decomposition of plant-derived organic matter by soil microorganisms. In addition to its effects on water quality and soil fertility, the decomposition of organic matter couples soil processes to climate, via the production and emission of greenhouse gases. In this presentation, I will review a number of key factors controlling the rate of decomposition of soil organic matter. In particular, I will discuss the importance of the spatial and temporal variations in redox conditions as drivers of soil respiration. The discussion will highlight the limitations of current soil respiration models based on partitioning soil organic matter in a finite number of pools of different degradability. In order to predict the sensitivity of soil respiration to anthropogenic pressures - including climate warming - it is crucial to relate the apparent degradability of soil organic matter to the geochemical and hydrological dynamics of the soil environment. Overall, there remains much scope for geochemists to help develop more robust, process-based, representations of soil respiration in global carbon models and climate predictions.

  9. Predicting soil respiration from peatlands.

    PubMed

    Rowson, J G; Worrall, F; Evans, M G; Dixon, S D

    2013-01-01

    This study considers the relative performance of six different models to predict soil respiration from upland peat. Predicting soil respiration is important for global carbon budgets and gap filling measured data from eddy covariance and closed chamber measurements. Further to models previously published new models are presented using two sub-soil zones and season. Models are tested using data from the Bleaklow plateau, southern Pennines, UK. Presented literature models include ANOVA using logged environmental data, the Arrhenius equation, modified versions of the Arrhenius equation to include soil respiration activation energy and water table depth. New models are proposed including the introduction of two soil zones in the peat profile, and season. The first new model proposes a zone of high CO(2) productivity related to increased soil microbial CO(2) production due to the supply of labile carbon from plant root exudates and root respiration. The second zone is a deeper zone where CO(2) production is lower with less labile carbon. A final model allows the zone of high CO(2) production to become dormant during winter months when plants will senesce and will vary depending upon vegetation type within a fixed location. The final model accounted for, on average, 31.9% of variance in net ecosystem respiration within 11 different restoration sites whilst, using the same data set, the best fitting literature equation only accounted for 18.7% of the total variance. Our results demonstrate that soil respiration models can be improved by explicitly accounting for seasonality and the vertically stratified nature of soil processes. These improved models provide an enhanced basis for calculating the peatland carbon budgets which are essential in understanding the role of peatlands in the global C cycle.

  10. Predicting soil respiration from peatlands.

    PubMed

    Rowson, J G; Worrall, F; Evans, M G; Dixon, S D

    2013-01-01

    This study considers the relative performance of six different models to predict soil respiration from upland peat. Predicting soil respiration is important for global carbon budgets and gap filling measured data from eddy covariance and closed chamber measurements. Further to models previously published new models are presented using two sub-soil zones and season. Models are tested using data from the Bleaklow plateau, southern Pennines, UK. Presented literature models include ANOVA using logged environmental data, the Arrhenius equation, modified versions of the Arrhenius equation to include soil respiration activation energy and water table depth. New models are proposed including the introduction of two soil zones in the peat profile, and season. The first new model proposes a zone of high CO(2) productivity related to increased soil microbial CO(2) production due to the supply of labile carbon from plant root exudates and root respiration. The second zone is a deeper zone where CO(2) production is lower with less labile carbon. A final model allows the zone of high CO(2) production to become dormant during winter months when plants will senesce and will vary depending upon vegetation type within a fixed location. The final model accounted for, on average, 31.9% of variance in net ecosystem respiration within 11 different restoration sites whilst, using the same data set, the best fitting literature equation only accounted for 18.7% of the total variance. Our results demonstrate that soil respiration models can be improved by explicitly accounting for seasonality and the vertically stratified nature of soil processes. These improved models provide an enhanced basis for calculating the peatland carbon budgets which are essential in understanding the role of peatlands in the global C cycle. PMID:23178842

  11. Soil respiration under different land uses in Eastern China.

    PubMed

    Fan, Li-Chao; Yang, Ming-Zhen; Han, Wen-Yan

    2015-01-01

    Land-use change has a crucial influence on soil respiration, which further affects soil nutrient availability and carbon stock. We monitored soil respiration rates under different land-use types (tea gardens with three production levels, adjacent woodland, and a vegetable field) in Eastern China at weekly intervals over a year using the dynamic closed chamber method. The relationship between soil respiration and environmental factors was also evaluated. The soil respiration rate exhibited a remarkable single peak that was highest in July/August and lowest in January. The annual cumulative respiration flux increased by 25.6% and 20.9% in the tea garden with high production (HP) and the vegetable field (VF), respectively, relative to woodland (WL). However, no significant differences were observed between tea gardens with medium production (MP), low production (LP), WL, and VF. Soil respiration rates were significantly and positively correlated with organic carbon, total nitrogen, and available phosphorous content. Each site displayed a significant exponential relationship between soil respiration and soil temperature measured at 5 cm depth, which explained 84-98% of the variation in soil respiration. The model with a combination of soil temperature and moisture was better at predicting the temporal variation of soil respiration rate than the single temperature model for all sites. Q10 was 2.40, 2.00, and 1.86-1.98 for VF, WL, and tea gardens, respectively, indicating that converting WL to VF increased and converting to tea gardens decreased the sensitivity of soil respiration to temperature. The equation of the multiple linear regression showed that identical factors, including soil organic carbon (SOC), soil water content (SWC), pH, and water soluble aluminum (WSAl), drove the changes in soil respiration and Q10 after conversion of land use. Temporal variations of soil respiration were mainly controlled by soil temperature, whereas spatial variations were

  12. Soil Respiration under Different Land Uses in Eastern China

    PubMed Central

    Fan, Li-Chao; Yang, Ming-Zhen; Han, Wen-Yan

    2015-01-01

    Land-use change has a crucial influence on soil respiration, which further affects soil nutrient availability and carbon stock. We monitored soil respiration rates under different land-use types (tea gardens with three production levels, adjacent woodland, and a vegetable field) in Eastern China at weekly intervals over a year using the dynamic closed chamber method. The relationship between soil respiration and environmental factors was also evaluated. The soil respiration rate exhibited a remarkable single peak that was highest in July/August and lowest in January. The annual cumulative respiration flux increased by 25.6% and 20.9% in the tea garden with high production (HP) and the vegetable field (VF), respectively, relative to woodland (WL). However, no significant differences were observed between tea gardens with medium production (MP), low production (LP), WL, and VF. Soil respiration rates were significantly and positively correlated with organic carbon, total nitrogen, and available phosphorous content. Each site displayed a significant exponential relationship between soil respiration and soil temperature measured at 5 cm depth, which explained 84–98% of the variation in soil respiration. The model with a combination of soil temperature and moisture was better at predicting the temporal variation of soil respiration rate than the single temperature model for all sites. Q10 was 2.40, 2.00, and 1.86–1.98 for VF, WL, and tea gardens, respectively, indicating that converting WL to VF increased and converting to tea gardens decreased the sensitivity of soil respiration to temperature. The equation of the multiple linear regression showed that identical factors, including soil organic carbon (SOC), soil water content (SWC), pH, and water soluble aluminum (WSAl), drove the changes in soil respiration and Q10 after conversion of land use. Temporal variations of soil respiration were mainly controlled by soil temperature, whereas spatial variations were

  13. Soil respiration vs. soil CO2 efflux: the role of CO2 storage flux in soil respiration models

    NASA Astrophysics Data System (ADS)

    Maier, Martin; Helmer, Schack-Kirchner; Ernst, Hildebrand

    2010-05-01

    Most studies implicitly consider soil surface efflux of CO2 to be the instantaneous soil respiration, thereby neglecting possible changes in the amount of CO2 stored in the soil pore-space. For the widely used chamber-based and micro-meteorological measurements, filling or depletion of this CO2 pool can result in either an under- or overestimation of the soil respiration. Soil temperature and moisture are the major abiotic factors controlling soil respiration, and are used as explanatory variables by most models. However, these two factors also influence soil gas transport, and thus, the amount of stored CO2. This effect can add undesired noise to soil respiration models or even interfere with the model parameters. To examine the effect of CO2 storage flux, we monitored both the soil CO2 efflux and the CO2 storage in the soil pore-space of a deep and well-aerated riparian soil. Measurements were carried out from March 2009 to March 2010 using an automated chamber system and CO2 concentration measurements at various depths (0.05 to 2.1 m) in the soil profile. First results show that the integration of the storage flux can lead to a significant divergence of soil respiration and soil CO2 efflux, potentially affecting respiration models. It will be discussed whether the integration of the storage flux either changes the overall parameter estimation or is only relevant to improve the understanding of particular meteorological situations.

  14. Influence of soil moisture on soil respiration

    NASA Astrophysics Data System (ADS)

    Fer, Miroslav; Kodesova, Radka; Nikodem, Antonin; Klement, Ales; Jelenova, Klara

    2015-04-01

    The aim of this work was to describe an impact of soil moisture on soil respiration. Study was performed on soil samples from morphologically diverse study site in loess region of Southern Moravia, Czech Republic. The original soil type is Haplic Chernozem, which was due to erosion changed into Regosol (steep parts) and Colluvial soil (base slope and the tributary valley). Soil samples were collected from topsoils at 5 points of the selected elevation transect and also from the parent material (loess). Grab soil samples, undisturbed soil samples (small - 100 cm3, and large - 713 cm3) and undisturbed soil blocks were taken. Basic soil properties were determined on grab soil samples. Small undisturbed soil samples were used to determine the soil water retention curves and the hydraulic conductivity functions using the multiple outflow tests in Tempe cells and a numerical inversion with HYDRUS 1-D. During experiments performed in greenhouse dry large undisturbed soil samples were wetted from below using a kaolin tank and cumulative water inflow due to capillary rise was measured. Simultaneously net CO2 exchange rate and net H2O exchange rate were measured using LCi-SD portable photosynthesis system with Soil Respiration Chamber. Numerical inversion of the measured cumulative capillary rise data using the HYDRUS-1D program was applied to modify selected soil hydraulic parameters for particular conditions and to simulate actual soil water distribution within each soil column in selected times. Undisturbed soil blocks were used to prepare thin soil sections to study soil-pore structure. Results for all soil samples showed that at the beginning of soil samples wetting the CO2 emission increased because of improving condition for microbes' activity. The maximum values were reached for soil column average soil water content between 0.10 and 0.15 cm3/cm3. Next CO2 emission decreased since the pore system starts filling by water (i.e. aggravated conditions for microbes

  15. Forest age stands affect soil respiration and litterfall in a Black pine forest managed by a shelterwood system in the Central Spain?

    NASA Astrophysics Data System (ADS)

    Hedo de Santiago, Javier; Borja, Manuel Esteban Lucas; Candel, David; Viñegla Pérez, Benjamin

    2016-04-01

    This study aims to investigate the effects that stand age and forest structure generates on soil respiration and litterfall quantity. The effect of stand age on these variables was studied in a shelterwood system Spanish Black pine chronosequence in central Iberian Peninsula composed of 0-20, 20-40, 40-60, 60-80, 80-100-year-old. For each stand age, six forest stands with similar characteristics of soil type and site preparation were used. Also, a forest area ranging 80-120 years old and without forest intervention was selected and used as control. We also measured organic matter, C:N ratio, soil moisture and pH in the top 10 mineral soil at each compartment. Soil respiration measurements were carried out in three time points (3, 8 and 12 days). Results showed a clear trend in soil respiration, comparing all the experimental areas. Soil respiration showed the same trend in all stands. It initially showed higher rates, reaching stability in the middle of the measurement process and finally lightly increasing the respiration rate. The older stands had significantly higher soil respiration than the younger stands. Soil organic matter values were also higher in the more mature stands. C:N ratio showed the opposite trend, showing lower values in the less mature stands. More mature stands clearly showed more quantity of litterfall than the younger ones and there was a positive correlation between soil respiration and litterfall. Finally, the multivariate PCA analysis clearly clustered three differenced groups: Control plot; from 100 to 40 years old and from 39 to 1 years old, taking into account both soil respiration and litterfall quantity, also separately. Our results suggest that the control plot has a better soil quality and that extreme forest stand ages (100-80 and 19-1 years old) and the associated forest structure generates differences in soil respiration.

  16. How Ecosystems Breathe: Measuring Respiration of Soil

    NASA Astrophysics Data System (ADS)

    McTammany, M. E.

    2005-05-01

    Curriculum for general ecology labs often uses in-lab exercises and computer simulations to demonstrate ecological principles rather than experimental field projects. In addition, ecosystem processes can be difficult to incorporate into general ecology labs because the techniques require sophisticated equipment or complex field designs. As an alternative to in-lab projects, I have integrated field measurement of soil respiration into my general ecology lab to teach students aspects of experimental design (sampling, replication, error, etc.) and to demonstrate how organism-level processes operate beyond single organisms in nature and are influenced by environmental conditions. In a program laden with biomedical interests, analogies between organisms and ecosystems are quite appealing to students. Students in my general ecology course complete a 2-week field project in which they measure soil respiration inside a dark microcosm chamber. We use 10% KOH to trap evolved CO2 and titrate unreacted KOH in lab using 1N HCl. The protocol is simple, only requires some chemicals, and can be used in many different habitats (including flower beds on campus) quite easily. Potential experiments could involve varying environmental conditions, such as soil moisture, nutrient availability, gaseous environment, carbon supply, or temperature, to affect soil respiration rate.

  17. Impact of environmental factors and biological soil crust types on soil respiration in a desert ecosystem.

    PubMed

    Feng, Wei; Zhang, Yuqing; Jia, Xin; Wu, Bin; Zha, Tianshan; Qin, Shugao; Wang, Ben; Shao, Chenxi; Liu, Jiabin; Fa, Keyu

    2014-01-01

    The responses of soil respiration to environmental conditions have been studied extensively in various ecosystems. However, little is known about the impacts of temperature and moisture on soils respiration under biological soil crusts. In this study, CO2 efflux from biologically-crusted soils was measured continuously with an automated chamber system in Ningxia, northwest China, from June to October 2012. The highest soil respiration was observed in lichen-crusted soil (0.93 ± 0.43 µmol m-2 s-1) and the lowest values in algae-crusted soil (0.73 ± 0.31 µmol m-2 s-1). Over the diurnal scale, soil respiration was highest in the morning whereas soil temperature was highest in the midday, which resulted in diurnal hysteresis between the two variables. In addition, the lag time between soil respiration and soil temperature was negatively correlated with the soil volumetric water content and was reduced as soil water content increased. Over the seasonal scale, daily mean nighttime soil respiration was positively correlated with soil temperature when moisture exceeded 0.075 and 0.085 m3 m-3 in lichen- and moss-crusted soil, respectively. However, moisture did not affect on soil respiration in algae-crusted soil during the study period. Daily mean nighttime soil respiration normalized by soil temperature increased with water content in lichen- and moss-crusted soil. Our results indicated that different types of biological soil crusts could affect response of soil respiration to environmental factors. There is a need to consider the spatial distribution of different types of biological soil crusts and their relative contributions to the total C budgets at the ecosystem or landscape level.

  18. Impact of environmental factors and biological soil crust types on soil respiration in a desert ecosystem.

    PubMed

    Feng, Wei; Zhang, Yuqing; Jia, Xin; Wu, Bin; Zha, Tianshan; Qin, Shugao; Wang, Ben; Shao, Chenxi; Liu, Jiabin; Fa, Keyu

    2014-01-01

    The responses of soil respiration to environmental conditions have been studied extensively in various ecosystems. However, little is known about the impacts of temperature and moisture on soils respiration under biological soil crusts. In this study, CO2 efflux from biologically-crusted soils was measured continuously with an automated chamber system in Ningxia, northwest China, from June to October 2012. The highest soil respiration was observed in lichen-crusted soil (0.93 ± 0.43 µmol m-2 s-1) and the lowest values in algae-crusted soil (0.73 ± 0.31 µmol m-2 s-1). Over the diurnal scale, soil respiration was highest in the morning whereas soil temperature was highest in the midday, which resulted in diurnal hysteresis between the two variables. In addition, the lag time between soil respiration and soil temperature was negatively correlated with the soil volumetric water content and was reduced as soil water content increased. Over the seasonal scale, daily mean nighttime soil respiration was positively correlated with soil temperature when moisture exceeded 0.075 and 0.085 m3 m-3 in lichen- and moss-crusted soil, respectively. However, moisture did not affect on soil respiration in algae-crusted soil during the study period. Daily mean nighttime soil respiration normalized by soil temperature increased with water content in lichen- and moss-crusted soil. Our results indicated that different types of biological soil crusts could affect response of soil respiration to environmental factors. There is a need to consider the spatial distribution of different types of biological soil crusts and their relative contributions to the total C budgets at the ecosystem or landscape level. PMID:25050837

  19. Impact of Environmental Factors and Biological Soil Crust Types on Soil Respiration in a Desert Ecosystem

    PubMed Central

    Feng, Wei; Zhang, Yuqing; Jia, Xin; Wu, Bin; Zha, Tianshan; Qin, Shugao; Wang, Ben; Shao, Chenxi; Liu, Jiabin; Fa, Keyu

    2014-01-01

    The responses of soil respiration to environmental conditions have been studied extensively in various ecosystems. However, little is known about the impacts of temperature and moisture on soils respiration under biological soil crusts. In this study, CO2 efflux from biologically-crusted soils was measured continuously with an automated chamber system in Ningxia, northwest China, from June to October 2012. The highest soil respiration was observed in lichen-crusted soil (0.93±0.43 µmol m−2 s−1) and the lowest values in algae-crusted soil (0.73±0.31 µmol m−2 s−1). Over the diurnal scale, soil respiration was highest in the morning whereas soil temperature was highest in the midday, which resulted in diurnal hysteresis between the two variables. In addition, the lag time between soil respiration and soil temperature was negatively correlated with the soil volumetric water content and was reduced as soil water content increased. Over the seasonal scale, daily mean nighttime soil respiration was positively correlated with soil temperature when moisture exceeded 0.075 and 0.085 m3 m−3 in lichen- and moss-crusted soil, respectively. However, moisture did not affect on soil respiration in algae-crusted soil during the study period. Daily mean nighttime soil respiration normalized by soil temperature increased with water content in lichen- and moss-crusted soil. Our results indicated that different types of biological soil crusts could affect response of soil respiration to environmental factors. There is a need to consider the spatial distribution of different types of biological soil crusts and their relative contributions to the total C budgets at the ecosystem or landscape level. PMID:25050837

  20. Modelling Soil respiration in agro-ecosystems

    NASA Astrophysics Data System (ADS)

    Delogu, Emilie; LeDantec, Valerie; Mordelet, Patrick; Buysse, Pauline; Aubinet, Marc; Pattey, Elizabeth

    2013-04-01

    A soil respiration model was developed to simulate soil respiration in crops on a daily time step. The soil heterotrophic respiration component was derived from Century (Parton et al., 1987). Soil organic carbon is divided into three major components including active, slow and passive soil carbon. Each pool has its own decomposition rate coefficient. Carbon flows between these pools are controlled by carbon inputs (crop residues), decomposition rate and microbial respiration loss parameters, both of which are a function of soil texture, soil temperature and soil water content. The model assumes that all C decompositions flows are associated with microbial activity and that microbial respiration occurs for each of these flows. Heterotrophic soil respiration is the sum of all these microbial respiration processes. To model the soil autotrophic respiration component, maintenance respiration is calculated from the nitrogen content and assuming an exponential relationship to account for temperature dependence (Ryan et al., 1991). Growth respiration is calculated assuming a dependence on both growth rate and construction cost of the considered organ (MacCree et al., 1982) A database, made of four different soil and climate conditions in mid-latitude was used to study the two components of the soil respiration model in wheat fields. Soil respiration were measured in three winter wheat fields at Lamasquère (43°49'N, 01°23'E, 2007) and Auradé (43°54'N, 01°10'E, 2008), South-West France and Lonzée (50°33'N, 4°44'E, 2007), Belgium, and in a spring wheat field at Ottawa (45°22'N, 75°43'W, 2007, 2011), Ontario, Canada. Manual closed chambers were used in the French sites. The Belgium and Canadian sites were equipped with automated closed chamber systems, which continuously collected 30-min soil respiration exchanges. All the sites were also equipped with eddy flux towers. When eddy flux data were collected over bare soil, the net ecosystem exchange (NEE) was equal to

  1. Autotrophic and heterotrophic components of soil respiration in permafrost zone.

    NASA Astrophysics Data System (ADS)

    Udovenko, Maria; Goncharova, Olga

    2016-04-01

    microbial respiration is 83%. A modified method of roots exclusion was tested during field trails in the areas of localization of "peat spots". It showed the following results: 41% of root respiration and 59% of microbial respiration. So, the contribution of root respiration in forest depending on the method varied from 5 to 17%, and on peatland root respiration varied from 41 to 56%. Thus, all methods gave positive result and are suitable for the separate determination of root and microbial respiration in permafrost-affected soils. However, for a more accurate assessment is necessary to increase the number of replications and the experiment period.

  2. Salinity and nutrient contents of tidal water affects soil respiration and carbon sequestration of high and low tidal flats of Jiuduansha wetlands in different ways.

    PubMed

    Hu, Yu; Wang, Lei; Fu, Xiaohua; Yan, Jianfang; Wu, Jihua; Tsang, Yiufai; Le, Yiquan; Sun, Ying

    2016-09-15

    Soils were collected from low tidal flats and high tidal flats of Shang shoal located upstream and Xia shoal located downstream with different tidal water qualities, in the Jiuduansha wetland of the Yangtze River estuary. Soil respiration (SR) in situ and soil abiotic and microbial characteristics were studied to clarify the respective differences in the effects of tidal water salinity and nutrient levels on SR and soil carbon sequestration in low and high tidal flats. In low tidal flats, higher total nitrogen (TN) and lower salinity in the tidal water of Shang shoal resulted in higher TN and lower salinity in its soils compared with Xia shoal. These would benefit β-Proteobacteria and Anaerolineae in Shang shoal soil, which might have higher heterotrophic microbial activities and thus soil microbial respiration and SR. In low tidal flats, where soil moisture was high and the major carbon input was active organic carbon from tidal water, increasing TN was a more important factor than salinity and obviously enhanced soil microbial heterotrophic activities, soil microbial respiration and SR. While, in high tidal flats, higher salinity in Xia shoal due to higher salinity in tidal water compared with Shang shoal benefited γ-Proteobacteria which might enhance autotrophic microbial activity, and was detrimental to β-Proteobacteria in Xia shoal soil. These might have led to lower soil microbial respiration and thus SR in Xia shoal compared with Shang shoal. In high tidal flats, where soil moisture was relatively lower and the major carbon input was plant biomass that was difficult to degrade, soil salinity was the major factor restraining microbial activities, soil microbial respiration and SR.

  3. Salinity and nutrient contents of tidal water affects soil respiration and carbon sequestration of high and low tidal flats of Jiuduansha wetlands in different ways.

    PubMed

    Hu, Yu; Wang, Lei; Fu, Xiaohua; Yan, Jianfang; Wu, Jihua; Tsang, Yiufai; Le, Yiquan; Sun, Ying

    2016-09-15

    Soils were collected from low tidal flats and high tidal flats of Shang shoal located upstream and Xia shoal located downstream with different tidal water qualities, in the Jiuduansha wetland of the Yangtze River estuary. Soil respiration (SR) in situ and soil abiotic and microbial characteristics were studied to clarify the respective differences in the effects of tidal water salinity and nutrient levels on SR and soil carbon sequestration in low and high tidal flats. In low tidal flats, higher total nitrogen (TN) and lower salinity in the tidal water of Shang shoal resulted in higher TN and lower salinity in its soils compared with Xia shoal. These would benefit β-Proteobacteria and Anaerolineae in Shang shoal soil, which might have higher heterotrophic microbial activities and thus soil microbial respiration and SR. In low tidal flats, where soil moisture was high and the major carbon input was active organic carbon from tidal water, increasing TN was a more important factor than salinity and obviously enhanced soil microbial heterotrophic activities, soil microbial respiration and SR. While, in high tidal flats, higher salinity in Xia shoal due to higher salinity in tidal water compared with Shang shoal benefited γ-Proteobacteria which might enhance autotrophic microbial activity, and was detrimental to β-Proteobacteria in Xia shoal soil. These might have led to lower soil microbial respiration and thus SR in Xia shoal compared with Shang shoal. In high tidal flats, where soil moisture was relatively lower and the major carbon input was plant biomass that was difficult to degrade, soil salinity was the major factor restraining microbial activities, soil microbial respiration and SR. PMID:27208721

  4. BOREAS TE-5 Soil Respiration Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

    2000-01-01

    The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. Soil respiration data were collected from 26-May-94 to 07-Sep-94 in the BOREAS NSA and SSA to compare the soil respiration rates in different forest sites using a LI-COR 6200 soil respiration chamber (model 6299). The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distrobuted Activity Archive Center (DAAC).

  5. Acclimation and soil moisture constrain sugar maple root respiration in experimentally warmed soil.

    PubMed

    Jarvi, Mickey P; Burton, Andrew J

    2013-09-01

    The response of root respiration to warmer soil can affect ecosystem carbon (C) allocation and the strength of positive feedbacks between climatic warming and soil CO2 efflux. This study sought to determine whether fine-root (<1 mm) respiration in a sugar maple (Acer saccharum Marsh.)-dominated northern hardwood forest would adjust to experimentally warmed soil, reducing C return to the atmosphere at the ecosystem scale to levels lower than that would be expected using an exponential temperature response function. Infrared heating lamps were used to warm the soil (+4 to +5 °C) in a mature sugar maple forest in a fully factorial design, including water additions used to offset the effects of warming-induced dry soil. Fine-root-specific respiration rates, root biomass, root nitrogen (N) concentration, soil temperature and soil moisture were measured from 2009 to 2011, with experimental treatments conducted from late 2010 to 2011. Partial acclimation of fine-root respiration to soil warming occurred, with soil moisture deficit further constraining specific respiration rates in heated plots. Fine-root biomass and N concentration remained unchanged. Over the 2011 growing season, ecosystem root respiration was not significantly greater in warmed soil. This result would not be predicted by models that allow respiration to increase exponentially with temperature and do not directly reduce root respiration in drier soil. PMID:24052568

  6. Acclimation and soil moisture constrain sugar maple root respiration in experimentally warmed soil.

    PubMed

    Jarvi, Mickey P; Burton, Andrew J

    2013-09-01

    The response of root respiration to warmer soil can affect ecosystem carbon (C) allocation and the strength of positive feedbacks between climatic warming and soil CO2 efflux. This study sought to determine whether fine-root (<1 mm) respiration in a sugar maple (Acer saccharum Marsh.)-dominated northern hardwood forest would adjust to experimentally warmed soil, reducing C return to the atmosphere at the ecosystem scale to levels lower than that would be expected using an exponential temperature response function. Infrared heating lamps were used to warm the soil (+4 to +5 °C) in a mature sugar maple forest in a fully factorial design, including water additions used to offset the effects of warming-induced dry soil. Fine-root-specific respiration rates, root biomass, root nitrogen (N) concentration, soil temperature and soil moisture were measured from 2009 to 2011, with experimental treatments conducted from late 2010 to 2011. Partial acclimation of fine-root respiration to soil warming occurred, with soil moisture deficit further constraining specific respiration rates in heated plots. Fine-root biomass and N concentration remained unchanged. Over the 2011 growing season, ecosystem root respiration was not significantly greater in warmed soil. This result would not be predicted by models that allow respiration to increase exponentially with temperature and do not directly reduce root respiration in drier soil.

  7. ELEVATED TEMPERATURE, SOIL MOISTURE AND SEASONALITY BUT NOT CO2 AFFECT CANOPY ASSIMILATION AND SYSTEM RESPIRATION IN SEEDLING DOUGLAS-FIR ECOSYSTEMS

    EPA Science Inventory

    We investigated the effects of elevated atmospheric CO2 and air temperature on C cycling in trees and associated soil system, focusing on canopy CO2 assimilation (Asys) and system CO2 loss through respiration (Rsys). We hypothesized that both elevated CO2 and elevated temperature...

  8. Winter soil respiration from different vegetation patches in the Yellow River Delta, China.

    PubMed

    Han, Guangxuan; Yu, Junbao; Li, Huabing; Yang, Liqiong; Wang, Guangmei; Mao, Peili; Gao, Yongjun

    2012-07-01

    Vegetation type and density exhibited a considerable patchy distribution at very local scales in the Yellow River Delta, due to the spatial variation of soil salinity and water scarcity. We proposed that soil respiration is affected by the spatial variations in vegetation type and soil chemical properties and tested this hypothesis in three different vegetation patches (Phragmites australis, Suaeda heteroptera and bare soil) in winter (from November 2010 to April 2011). At diurnal scale, soil respiration all displayed single-peak curves and asymmetric patterns in the three vegetation patches; At seasonal scale, soil respiration all declined steadily until February, and then increased to a peak in next April. But, the magnitude of soil respiration showed significant differences among the three sites. Mean soil respiration rates in winter were 0.60, 0.45 and 0.17 μmol CO(2) m(-2) s(-1) for the Phragmites australis, Suaeda heteroptera and bare soil, respectively. The combined effect of soil temperature and soil moisture accounted for 58-68 % of the seasonal variation of winter soil respiration. The mean soil respiration revealed positive and linear correlations with total N, total N and SOC storages at 0-20 cm depth, and plant biomass among the three sites. We conclude that the patchy distribution of plant biomass and soil chemical properties (total C, total N and SOC) may affect decomposition rate of soil organic matter in winter, thereby leading to spatial variations in soil respiration. PMID:22576142

  9. Winter Soil Respiration from Different Vegetation Patches in the Yellow River Delta, China

    NASA Astrophysics Data System (ADS)

    Han, Guangxuan; Yu, Junbao; Li, Huabing; Yang, Liqiong; Wang, Guangmei; Mao, Peili; Gao, Yongjun

    2012-07-01

    Vegetation type and density exhibited a considerable patchy distribution at very local scales in the Yellow River Delta, due to the spatial variation of soil salinity and water scarcity. We proposed that soil respiration is affected by the spatial variations in vegetation type and soil chemical properties and tested this hypothesis in three different vegetation patches ( Phragmites australis, Suaeda heteroptera and bare soil) in winter (from November 2010 to April 2011). At diurnal scale, soil respiration all displayed single-peak curves and asymmetric patterns in the three vegetation patches; At seasonal scale, soil respiration all declined steadily until February, and then increased to a peak in next April. But, the magnitude of soil respiration showed significant differences among the three sites. Mean soil respiration rates in winter were 0.60, 0.45 and 0.17 μmol CO2 m-2 s-1 for the Phragmites australis, Suaeda heteroptera and bare soil, respectively. The combined effect of soil temperature and soil moisture accounted for 58-68 % of the seasonal variation of winter soil respiration. The mean soil respiration revealed positive and linear correlations with total N, total N and SOC storages at 0-20 cm depth, and plant biomass among the three sites. We conclude that the patchy distribution of plant biomass and soil chemical properties (total C, total N and SOC) may affect decomposition rate of soil organic matter in winter, thereby leading to spatial variations in soil respiration.

  10. Tillage Effects on Soil Properties & Respiration

    NASA Astrophysics Data System (ADS)

    Rusu, Teodor; Bogdan, Ileana; Moraru, Paula; Pop, Adrian; Duda, Bogdan; Cacovean, Horea; Coste, Camelia

    2015-04-01

    Soil tillage systems can be able to influence soil compaction, water dynamics, soil temperature and soil structural condition. These processes can be expressed as changes of soil microbiological activity, soil respiration and sustainability of agriculture. Objectives of this study were: 1) to assess the effects of tillage systems (Conventional System-CS, Minimum Tillage-MT, No-Tillage-NT) on soil compaction, soil temperature, soil moisture and soil respiration and 2) to establish the relationship that exists in changing soil properties. Three treatments were installed: CS-plough + disc; MT-paraplow + rotary grape; NT-direct sowing. The study was conducted on an Argic-Stagnic Faeoziom. The MT and NT applications reduce or completely eliminate the soil mobilization, due to this, soil is compacted in the first year of application. The degree of compaction is directly related to soil type and its state of degradation. The state of soil compaction diminished over time, tending toward a specific type of soil density. Soil moisture was higher in NT and MT at the time of sowing and in the early stages of vegetation and differences diminished over time. Moisture determinations showed statistically significant differences. The MT and NT applications reduced the thermal amplitude in the first 15 cm of soil depth and increased the soil temperature by 0.5-2.20C. The determinations confirm the effect of soil tillage system on soil respiration; the daily average was lower at NT (315-1914 mmoli m-2s-1) and followed by MT (318-2395 mmoli m-2s-1) and is higher in the CS (321-2480 mmol m-2s-1). Comparing with CS, all the two conservation tillage measures decreased soil respiration, with the best effects of no-tillage. An exceeding amount of CO2 produced in the soil and released into the atmosphere, resulting from aerobic processes of mineralization of organic matter (excessive loosening) is considered to be not only a way of increasing the CO2 in the atmosphere, but also a loss of

  11. [Soil respiration in subtropical forests and model simulation of its relationships with soil temperature and moisture content].

    PubMed

    Jiang, Yan; Wang, Bing; Wang, Yu-ru; Yang, Qing-pei

    2010-07-01

    By using Li-6400-09 system, an in situ measurement on the soil respiration, soil temperature, and soil moisture content in three main forest types (evergreen broadleaved forest, Cunninghamia lanceolata plantation, and Phyllostachys pubescens forest) in subtropical area of China was conducted, with the relationships between soil respiration and soil temperature and moisture content simulated by several models. The C flux of soil respiration in P. pubescens forest, evergreen broadleaved forest, and C. lanceolata plantation was 12.84, 11.70, and 7.12 t C x hm(-2) x a(-1), respectively, and the soil respiration in these three forest types had similar diurnal and seasonal variations, with the maximum value at 11:00-12:00 and the minimum value at 1:00-3:00, and the highest value in August and September while the lowest value in December and January. Van't Hoff equation and Lloyd & Taylor function had less difference in describing the relationships between soil respiration and soil temperature, while the soil respiration rate predicted by Lloyd & Taylor function was smaller than the observed value. Quadratic model and power function model could well simulate the relationship between soil respiration and soil moisture content. Soil moisture content positively or negatively affected soil respiration, but the effects only reached significant level in C. lanceolata plantation. Comparing with single-factor equation, two-factor equation (soil temperature and moisture content) could better describe the responses of soil respiration to changed soil temperature and moisture content. Multivariate analysis of covariance showed that after eliminating the effects of soil temperature and moisture content, forest type had significant effects on soil respiration (R2 = 0.541). Other factors, such as air temperature, air relative humidity, and photosynthetic radiation also affected soil respiration, and the effects of air temperature reached significant level.

  12. Soil respiration under climate warming: differential response of heterotrophic and autotrophic respiration.

    PubMed

    Wang, Xin; Liu, Lingli; Piao, Shilong; Janssens, Ivan A; Tang, Jianwu; Liu, Weixing; Chi, Yonggang; Wang, Jing; Xu, Shan

    2014-10-01

    Despite decades of research, how climate warming alters the global flux of soil respiration is still poorly characterized. Here, we use meta-analysis to synthesize 202 soil respiration datasets from 50 ecosystem warming experiments across multiple terrestrial ecosystems. We found that, on average, warming by 2 °C increased soil respiration by 12% during the early warming years, but warming-induced drought partially offset this effect. More significantly, the two components of soil respiration, heterotrophic respiration and autotrophic respiration showed distinct responses. The warming effect on autotrophic respiration was not statistically detectable during the early warming years, but nonetheless decreased with treatment duration. In contrast, warming by 2 °C increased heterotrophic respiration by an average of 21%, and this stimulation remained stable over the warming duration. This result challenged the assumption that microbial activity would acclimate to the rising temperature. Together, our findings demonstrate that distinguishing heterotrophic respiration and autotrophic respiration would allow us better understand and predict the long-term response of soil respiration to warming. The dependence of soil respiration on soil moisture condition also underscores the importance of incorporating warming-induced soil hydrological changes when modeling soil respiration under climate change.

  13. Biocrusts modulate warming and rainfall exclusion effects on soil respiration in a semi-arid grassland

    PubMed Central

    Escolar, Cristina; Maestre, Fernando T.; Rey, Ana

    2015-01-01

    Soil surface communities composed of cyanobacteria, algae, mosses, liverworts, fungi, bacteria and lichens (biocrusts) largely affect soil respiration in dryland ecosystems. Climate change is expected to have large effects on biocrusts and associated ecosystem processes. However, few studies so far have experimentally assessed how expected changes in temperature and rainfall will affect soil respiration in biocrust-dominated ecosystems. We evaluated the impacts of biocrust development, increased air temperature and decreased precipitation on soil respiration dynamics during dry (2009) and wet (2010) years, and investigated the relative importance of soil temperature and moisture as environmental drivers of soil respiration, in a semiarid grassland from central Spain. Soil respiration rates were significantly lower in the dry than during the wet year, regardless of biocrust cover. Warming increased soil respiration rates, but this response was only significant in biocrust-dominated areas (> 50% biocrust cover). Warming also increased the temperature sensitivity (Q10 values) of soil respiration in biocrust-dominated areas, particularly during the wet year. The combination of warming and rainfall exclusion had similar effects in low biocrust cover areas. Our results highlight the importance of biocrusts as a modulator of soil respiration responses to both warming and rainfall exclusion, and indicate that they must be explicitly considered when evaluating soil respiration responses to climate change in drylands. PMID:25914428

  14. Soil respiration, labile carbon pools, and enzyme activities as affected by tillage practices in a tropical rice-maize-cowpea cropping system.

    PubMed

    Neogi, S; Bhattacharyya, P; Roy, K S; Panda, B B; Nayak, A K; Rao, K S; Manna, M C

    2014-07-01

    In order to identify the viable option of tillage practices in rice-maize-cowpea cropping system that could cut down soil carbon dioxide (CO2) emission, sustain grain yield, and maintain better soil quality in tropical low land rice ecology soil respiration in terms of CO2 emission, labile carbon (C) pools, water-stable aggregate C fractions, and enzymatic activities were investigated in a sandy clay loam soil. Soil respiration is the major pathway of gaseous C efflux from terrestrial systems and acts as an important index of ecosystem functioning. The CO2-C emissions were quantified in between plants and rows throughout the year in rice-maize-cowpea cropping sequence both under conventional tillage (CT) and minimum tillage (MT) practices along with soil moisture and temperature. The CO2-C emissions, as a whole, were 24 % higher in between plants than in rows, and were in the range of 23.4-78.1, 37.1-128.1, and 28.6-101.2 mg m(-2) h(-1) under CT and 10.7-60.3, 17.3-99.1, and 17.2-79.1 mg m(-2) h(-1) under MT in rice, maize, and cowpea, respectively. The CO2-C emission was found highest under maize (44 %) followed by rice (33 %) and cowpea (23 %) irrespective of CT and MT practices. In CT system, the CO2-C emission increased significantly by 37.1 % with respect to MT on cumulative annual basis including fallow. The CO2-C emission per unit yield was at par in rice and cowpea signifying the beneficial effect of MT in maintaining soil quality and reduction of CO2 emission. The microbial biomass C (MBC), readily mineralizable C (RMC), water-soluble C (WSC), and permanganate-oxidizable C (PMOC) were 19.4, 20.4, 39.5, and 15.1 % higher under MT than CT. The C contents in soil aggregate fraction were significantly higher in MT than CT. Soil enzymatic activities like, dehydrogenase, fluorescein diacetate, and β-glucosidase were significantly higher by 13.8, 15.4, and 27.4 % under MT compared to CT. The soil labile C pools, enzymatic activities, and

  15. Age of respired carbon in differently managed grassland and forest soils

    NASA Astrophysics Data System (ADS)

    Schoening, Ingo; Trumbore, Susan; Solly, Emily; Muhr, Jan; Schrumpf, Marion

    2013-04-01

    Grassland management (fertilization, grazing, mowing) and forest management (harvesting, thinning) directly affect biomass production and related leaf and root litter input to the soil. Understanding effects of land management on soil carbon fluxes is therefore critical. We examined the effect of land use and management on soil respiration and the age of respired soil carbon. Soil samples originated from grassland and forest plots in three different German regions. Sieved surface soil samples (0-10 cm) were incubated (20°C, 60% WHC) for 14 days. The respired CO2 was collected and 14C contents in the CO2 of 150 incubated samples were determined with accelerator mass spectrometry (AMS). Large changes recorded in 14C in the atmosphere since atmospheric weapons testing in the 1960s allow precise determination of the mean age of emitted soil carbon. In our study, the rate of respiration was higher in grassland soils (33 ± 10 µg C-CO2 per g dry soil per day) compared to forest soils (14 ± 7 µg C-CO2 per g dry soil per day). Results indicate a strong relation between respiration rates and grassland management with lower soil respiration in more fertilized plots. This relation was not found at sites where degraded peatlands were used as grasslands. At those sites, respiration rates were mainly driven by the soil organic carbon concentration. In forest soils, we did not find any relation between soil respiration and forest management. The 14C contents of the respired CO2 were lower in grassland soils (Percentage Modern carbon content: 104±2%) compared to forest soils (Percentage Modern Carbon content: 108±5%). This indicates that the carbon respired in forests is generally several years to more than a decade older than the carbon respired in grasslands. In grasslands, the 14C is positively related to the respiration rate and negatively related to fertilization. Again, degraded peat soils, where old carbon is released during incubation, were the exception to this

  16. Impact of changes in spring snow pack depth on subalpine forest soil respiration

    NASA Astrophysics Data System (ADS)

    Trahan, N. A.; Lee, S.; Bowling, D. R.; Monson, R. K.

    2012-12-01

    The amount of late winter snow and the timing of snow melt control rates of carbon sequestration in Colorado subalpine forests, but the influence of snow on soil respiration during the period of summer and spring carbon uptake is uncertain. We investigated the effects of spring snow pack depth on the autotrophic and heterotrophic components of soil respiration over two summer growing seasons in a high elevation forest in Colorado, USA. Spring snowpack was increased or decreased relative to ambient snow conditions in plots with girdled and ungirdled trees, and soil respiration rates, soil carbon pools and the δ13C of soil respiration were measured throughout the subsequent growing seasons. Girdling, used to identify heterotrophic versus autotrophic respiration, decreased soil respiration rates by 38%, extractable soil dissolved organic carbon by 42% and microbial biomass carbon by 42% in year one, demonstrating the importance of the transport of sugars from the shoot to the root, subsequent root exudation and fine root production to soil respiration. While snow additions did not affect snow respiration rates in 2008, they increased soil respiration rates by 13% in plots with ungirdled trees for a 22-day period in 2009. Snow amendment plots with ungirdled trees displayed an ~1 ‰ depleted δ13C signal after snow manipulations that persisted through the early growing season in both years. These results suggest that gross primary productivity (GPP) and ecosystem respiration (RE) are linked through rhizodeposition, and that the autotrophic component of soil respiration may be sensitive to the effect of snow moisture availability on the photosynthetic water-use efficiency of trees, and a more sensitive indicator of respiration responses to dynamics in snow pack depth compared to the overall respiration flux rates.

  17. [Effects of soil temperature and humidity on soil respiration rate under Pinus sylvestriformis forest].

    PubMed

    Liu, Ying; Han, Shijie; Hu, Yanling; Dai, Guanhua

    2005-09-01

    Employing root-wrenching method and LI-6400-09 soil respiration chamber, this paper measured the diurnal changes of soil respiration rate with and without roots in situ on June 17, August 5, and October 10, 2003. The seasonal changes of soil respiration were also measured from May to September, 2004. The results showed that both the total and the root-wrenched soil respiration appeared single diurnal pattern, with the peaks presented during 12:00-14:00. The diurnal fluctuation of soil respiration on August 5 was smaller than that on June 17 and October 10. There were also obvious seasonal changes in total and root-wrenched soil respiration, as well as in root respiration, which were higher from June to August but lower in May and September. The average total soil respiration, root-wrenched soil respiration, and root respiration were 3.12, 1.94 and 1.18 micromol CO2 x m(-2) s(-1), respectively, and the contribution of roots to total soil respiration ranged from 26.5% to 52.6% from May to September, 2004. There were exponential correlations between respiration rate and soil temperature, and linear correlations between respiration rate and soil humidity. The Q10 values were 2.44, 2.55 and 2.27 for total soil respiration, root-wrenched soil respiration, and root respiration, respectively. The effect of soil temperature on root-wrenched soil respiration was lager than that on total soil respiration and root respiration. Soil humidity had a larger effect on total soil respiration than on root respiration and root-wrenched soil respiration. PMID:16355765

  18. [Effects of Tillage on Soil Respiration and Root Respiration Under Rain-Fed Summer Corn Field].

    PubMed

    Lu, Xing-li; Liao, Yun-cheng

    2015-06-01

    To explore the effects of different tillage systems on soil respiration and root respiration under rain-fed condition. Based on a short-term experiment, this paper investigated soil respiration in summer corn growth season under four tillage treatments including subsoiling tillage (ST), no tillage (NT), rotary tillage (RT) and moldboard plow tillage (CT). The contribution of root respiration using root exclusion method was also discussed. The results showed that soil respiration rate presented a single peak trend under four tillage methods during the summer corn growing season, and the maximum value was recorded at the heading stage. The trends of soil respiration were as follows: heading stage > flowering stage > grain filling stage > maturity stage > jointing stage > seedling stage. The trends of soil respiration under different tillage systems were as follows: CT > ST > RT > NT. There was a significant correlation between soil respiration rate and soil temperatures (P < 0.05), which could explain 35%-75% variability of soil respiration using exponential function equation. However, there was no significant correlation between soil respiration rate and soil moisture. Root respiration accounted for 45.13%-56.86% of the proportion of soil respiratio n with the mean value 51.72% during the summer corn growing season under different tillage systems. Therefore, root exclusion method could be used to study the contribution of crop growth to carbon emission, to compare effects of different tillage systems on the contribution of root respiration provides the bases for selecting the measures to slow down the decomposition of soil carbon.

  19. Soil respiration partition and its components in the total agro-ecosystem respiration

    NASA Astrophysics Data System (ADS)

    Delogu, Emilie; LeDantec, Valerie; Mordelet, Patrick; Buysse, Pauline; Aubinet, Marc; Pattey, Elizabeth; Mary, Bruno

    2013-04-01

    Close to 15% of the Earth's terrestrial surface is used for cropland. In the context of global warming, and acknowledged by the Kyoto Protocol, agricultural soils could be a significant sink for atmospheric CO2. Understanding the factors influencing carbon fluxes of agricultural soils is essential for implementing efficient mitigation practices. Most of the soil respiration modeling studies was carried out in forest ecosystems, but only a few was carried out in agricultural ecosystems. In the study, we evaluated simple formalisms to model soil respiration using wheat data from four contrasting geographical mi-latitude regions. Soil respiration were measured in three winter wheat fields at Lamasquère (43°49'N, 01°23'E, 2007) and Auradé (43°54'N, 01°10'E, 2008), South-West France and Lonzée (50°33'N, 4°44'E, 2007), Belgium, and in a spring wheat field at Ottawa (45°22'N, 75°43'W, 2007, 2011), Ontario, Canada. Manual closed chambers were used in the French sites. The Belgium and Canadian sites were equipped with automated closed chamber systems, which continuously collected 30-min soil respiration exchanges. All the sites were also equipped with eddy flux towers. When eddy flux data were collected over bare soil, the net ecosystem exchange (NEE) was equal to soil respiration exchange. These NEE data were used to validate the model. Different biotic and abiotic descriptors were used to model daily soil respiration and its heterotrophic and autotrophic components: soil temperature, soil relative humidity, Gross Primary Productivity (GPP), shoot biomass, crop height, with different formalisms. It was interesting to conclude that using biotic descriptors did not improve the performances of the model. In fact, a combination of abiotic descriptors (soil humidity and soil temperature) allowed significant model formalism to model soil respiration. The simple soil respiration model was used to calculate the heterotrophic and autotrophic source contributions to

  20. Effects of fire and harvest on soil respiration in a mixed-conifer forest

    NASA Astrophysics Data System (ADS)

    Dore, S.; Fry, D.; Stephens, S.

    2012-12-01

    Forest ecosystems, and in particular forest soils, constitute a major reservoir of global terrestrial carbon and soil respiration is the largest carbon loss from these ecosystems. Disturbances can affect soil respiration, causing physical and chemical changes in soil characteristics, adding both, above and belowground necromass, and changing microclimatic conditions. This could signify an important and long term carbon loss, even higher than the carbon directly removed by the harvest or during fire. These losses need to be included when quantifying the net carbon balance of forests. We measured the impacts of prescribed fire and clear-cut tree harvest on soil respiration in a mixed-conifer forest in the central Sierra Nevada. The prescribed fire treatment was implemented in 2002 and again in 2009. Four areas were clear-cut harvested in 2010. In half of these units the soils were mechanically ripped to reduce soil compaction, a common practice in the Sierra Nevada industrial forest lands. Soil respiration was measured using two different techniques: the chamber method and the gradient method. Soil respiration was affected by treatments in two different ways. First, treatments changed soil temperature and soil water content, the main abiotic factors controlling soil respiration. The clear cut and the prescribed fire treatments created higher maximum soil temperature and more available soil water content, environmental conditions favorable to soil respiration. However, the loss of trees and thus fine roots, and the decrease of soil litter and organic layers, because of their combustion or removal, had a negative effect on soil respiration that was stronger than the positive effect due to more favorable post disturbance environmental conditions. Soil respiration rates remained steady 1-2 years after treatments and no increase or spikes of soil respiration were measured after treatments. Continuous measurements of CO2 concentrations at different soil depths improved our

  1. Soil Respiration and Student Inquiry: A Perfect Match

    ERIC Educational Resources Information Center

    Hoyt, Catherine Marie; Wallenstein, Matthew David

    2011-01-01

    This activity explores the cycling of carbon between the atmosphere (primarily as CO[subscript 2]) and biomass in plants, animals, and microscopic organisms. Students design soil respiration experiments using a protocol that resembles current practice in soil ecology. Three methods for measuring soil respiration are presented. Student-derived…

  2. Effects of myclobutanil on soil microbial biomass, respiration, and soil nitrogen transformations.

    PubMed

    Ju, Chao; Xu, Jun; Wu, Xiaohu; Dong, Fengshou; Liu, Xingang; Zheng, Yongquan

    2016-01-01

    A 3-month-long experiment was conducted to ascertain the effects of different concentrations of myclobutanil (0.4 mg kg(-1) soil [T1]; 1.2 mg kg(-1) soil [T3]; and 4 mg kg(-1) soil [T10]) on soil microbial biomass, respiration, and soil nitrogen transformations using two typical agricultural soils (Henan fluvo-aquic soil and Shanxi cinnamon soil). Soil was sampled after 7, 15, 30, 60, and 90 days of incubation to determine myclobutanil concentration and microbial parameters: soil basal respiration (RB), microbial biomass carbon (MBC) and nitrogen (MBN), NO(-)3-N and NH(+)4-N concentrations, and gene abundance of total bacteria, N2-fixing bacteria, fungi, ammonia-oxidizing archaea (AOA), and ammonia-oxidizing bacteria (AOB). The half-lives of the different doses of myclobutanil varied from 20.3 to 69.3 d in the Henan soil and from 99 to 138.6 d in the Shanxi soil. In the Henan soil, the three treatments caused different degrees of short-term inhibition of RB and MBC, NH(+)4-N, and gene abundance of total bacteria, fungi, N2-fixing bacteria, AOA, and AOB, with the exception of a brief increase in NO(-)3-N content during the T10 treatment. The MBN (immobilized nitrogen) was not affected. In the Shanxi soil, MBC, the populations of total bacteria, fungi, and N2-fixing bacteria, and NH(+)4-N concentration were not significantly affected by myclobutanil. The RB and MBN were decreased transitorily in the T10 treatment. The NO(-)3-N concentrations and the abundance of both AOA and AOB were erratically stimulated by myclobutanil. Regardless of whether stimulation or suppression occurred, the effects of myclobutanil on the two soil types were short term. In summary, myclobutanil had no long-term negative effects on the soil microbial biomass, respiration, and soil nitrogen transformations in the two types of soil, even at 10-fold the recommended dosage.

  3. Seasonal Patterns of Soil Respiration and Related Soil Biochemical Properties under Nitrogen Addition in Winter Wheat Field.

    PubMed

    Liang, Guopeng; Houssou, Albert A; Wu, Huijun; Cai, Dianxiong; Wu, Xueping; Gao, Lili; Li, Jing; Wang, Bisheng; Li, Shengping

    2015-01-01

    Understanding the changes of soil respiration under increasing N fertilizer in cropland ecosystems is crucial to accurately predicting global warming. This study explored seasonal variations of soil respiration and its controlling biochemical properties under a gradient of Nitrogen addition during two consecutive winter wheat growing seasons (2013-2015). N was applied at four different levels: 0, 120, 180 and 240 kg N ha(-1) year(-1) (denoted as N0, N12, N18 and N24, respectively). Soil respiration exhibited significant seasonal variation and was significantly affected by soil temperature with Q10 ranging from 2.04 to 2.46 and from 1.49 to 1.53 during 2013-2014 and 2014-2015 winter wheat growing season, respectively. Soil moisture had no significant effect on soil respiration during 2013-2014 winter wheat growing season but showed a significant and negative correlation with soil respiration during 2014-2015 winter wheat growing season. Soil respiration under N24 treatment was significantly higher than N0 treatment. Averaged over the two growing seasons, N12, N18 and N24 significantly increased soil respiration by 13.4, 16.4 and 25.4% compared with N0, respectively. N addition also significantly increased easily extractable glomalin-related soil protein (EEG), soil organic carbon (SOC), total N, ammonium N and nitrate N contents. In addition, soil respiration was significantly and positively correlated with β-glucosidase activity, EEG, SOC, total N, ammonium N and nitrate N contents. The results indicated that high N fertilization improved soil chemical properties, but significantly increased soil respiration. PMID:26629695

  4. Seasonal Patterns of Soil Respiration and Related Soil Biochemical Properties under Nitrogen Addition in Winter Wheat Field.

    PubMed

    Liang, Guopeng; Houssou, Albert A; Wu, Huijun; Cai, Dianxiong; Wu, Xueping; Gao, Lili; Li, Jing; Wang, Bisheng; Li, Shengping

    2015-01-01

    Understanding the changes of soil respiration under increasing N fertilizer in cropland ecosystems is crucial to accurately predicting global warming. This study explored seasonal variations of soil respiration and its controlling biochemical properties under a gradient of Nitrogen addition during two consecutive winter wheat growing seasons (2013-2015). N was applied at four different levels: 0, 120, 180 and 240 kg N ha(-1) year(-1) (denoted as N0, N12, N18 and N24, respectively). Soil respiration exhibited significant seasonal variation and was significantly affected by soil temperature with Q10 ranging from 2.04 to 2.46 and from 1.49 to 1.53 during 2013-2014 and 2014-2015 winter wheat growing season, respectively. Soil moisture had no significant effect on soil respiration during 2013-2014 winter wheat growing season but showed a significant and negative correlation with soil respiration during 2014-2015 winter wheat growing season. Soil respiration under N24 treatment was significantly higher than N0 treatment. Averaged over the two growing seasons, N12, N18 and N24 significantly increased soil respiration by 13.4, 16.4 and 25.4% compared with N0, respectively. N addition also significantly increased easily extractable glomalin-related soil protein (EEG), soil organic carbon (SOC), total N, ammonium N and nitrate N contents. In addition, soil respiration was significantly and positively correlated with β-glucosidase activity, EEG, SOC, total N, ammonium N and nitrate N contents. The results indicated that high N fertilization improved soil chemical properties, but significantly increased soil respiration.

  5. Seasonal Patterns of Soil Respiration and Related Soil Biochemical Properties under Nitrogen Addition in Winter Wheat Field

    PubMed Central

    Liang, Guopeng; Houssou, Albert A.; Wu, Huijun; Cai, Dianxiong; Wu, Xueping; Gao, Lili; Li, Jing; Wang, Bisheng; Li, Shengping

    2015-01-01

    Understanding the changes of soil respiration under increasing N fertilizer in cropland ecosystems is crucial to accurately predicting global warming. This study explored seasonal variations of soil respiration and its controlling biochemical properties under a gradient of Nitrogen addition during two consecutive winter wheat growing seasons (2013–2015). N was applied at four different levels: 0, 120, 180 and 240 kg N ha-1 year-1 (denoted as N0, N12, N18 and N24, respectively). Soil respiration exhibited significant seasonal variation and was significantly affected by soil temperature with Q10 ranging from 2.04 to 2.46 and from 1.49 to 1.53 during 2013–2014 and 2014–2015 winter wheat growing season, respectively. Soil moisture had no significant effect on soil respiration during 2013–2014 winter wheat growing season but showed a significant and negative correlation with soil respiration during 2014–2015 winter wheat growing season. Soil respiration under N24 treatment was significantly higher than N0 treatment. Averaged over the two growing seasons, N12, N18 and N24 significantly increased soil respiration by 13.4, 16.4 and 25.4% compared with N0, respectively. N addition also significantly increased easily extractable glomalin-related soil protein (EEG), soil organic carbon (SOC), total N, ammonium N and nitrate N contents. In addition, soil respiration was significantly and positively correlated with β-glucosidase activity, EEG, SOC, total N, ammonium N and nitrate N contents. The results indicated that high N fertilization improved soil chemical properties, but significantly increased soil respiration. PMID:26629695

  6. Effects of Tillage Practices on Soil Organic Carbon and Soil Respiration

    NASA Astrophysics Data System (ADS)

    Rusu, Teodor; Ioana Moraru, Paula; Bogdan, Ileana; Ioan Pop, Adrian

    2016-04-01

    Soil tillage system and its intensity modify by direct and indirect action soil temperature, moisture, bulk density, porosity, penetration resistance and soil structural condition. Minimum tillage and no-tillage application reduce or completely eliminate the soil mobilization, due to this, soil is compacted in the first years of application. The degree of compaction is directly related to soil type and its state of degradation. All this physicochemical changes affect soil biology and soil respiration. Soil respiration leads to CO2 emissions from soil to the atmosphere, in significant amounts for the global carbon cycle. Soil respiration is one measure of biological activity and decomposition. Soil capacity to produce CO2 varies depending on soil, season, intensity and quality of agrotechnical tillage, soil water, cultivated plant and fertilizer. Our research follows the effects of the three tillage systems: conventional system, minimum tillage and no-tillage on soil respiration and finally on soil organic carbon on rotation soybean - wheat - maize, obtained on an Argic Faeoziom from the Somes Plateau, Romania. To quantify the change in soil respiration under different tillage practices, determinations were made for each crop in four vegetative stages (spring, 5-6 leaves, bean forming, harvest). Soil monitoring system of CO2 and O2 included gradient method, made by using a new generation of sensors capable of measuring CO2 concentration in-situ and quasi-instantaneous in gaseous phase. At surface soil respiration is made by using ACE Automated Soil CO2 Exchange System. These areas were was our research presents a medium multi annual temperature of 8.20C medium of multi annual rain drowns: 613 mm. The experimental variants chosen were: i). Conventional system: reversible plough (22-25 cm) + rotary grape (8-10 cm); ii). Minimum tillage system: paraplow (18-22 cm) + rotary grape (8-10 cm); iii). No-tillage. The experimental design was a split-plot design with three

  7. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management.

    PubMed

    Wang, Zhen; Ji, Lei; Hou, Xiangyang; Schellenberg, Michael P

    2016-01-01

    Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures) on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17 μmol.m(-2).s(-1)) and clipping (2.06 μmol.m(-2).s(-1)) than under grazing (1.65 μmol.m-(2).s(-1)) over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP). Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP) and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content) and biotic (ANPP and BNPP) factors regulate soil respiration in the semiarid temperate grassland of northern China. PMID:26808376

  8. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management.

    PubMed

    Wang, Zhen; Ji, Lei; Hou, Xiangyang; Schellenberg, Michael P

    2016-01-01

    Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures) on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17 μmol.m(-2).s(-1)) and clipping (2.06 μmol.m(-2).s(-1)) than under grazing (1.65 μmol.m-(2).s(-1)) over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP). Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP) and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content) and biotic (ANPP and BNPP) factors regulate soil respiration in the semiarid temperate grassland of northern China.

  9. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management

    PubMed Central

    Hou, Xiangyang; Schellenberg, Michael P.

    2016-01-01

    Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures) on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17μmol.m−2.s−1) and clipping (2.06μmol.m−2.s−1) than under grazing (1.65μmol.m−2.s−1) over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP). Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP) and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content) and biotic (ANPP and BNPP) factors regulate soil respiration in the semiarid temperate grassland of northern China. PMID:26808376

  10. [Characteristics of Soil Respiration along Eroded Sloping Land with Different SOC Background on the Hilly Loess Plateau].

    PubMed

    Chen, Gai; Xu, Ming-xiang; Zhang, Ya-feng; Wang, Chao-hua; Fan, Hui-min; Wang, Shan-shan

    2015-09-01

    This study aimed to characterize soil respiration along eroded sloping land at erosion and deposition area under different soil organic carbon(SOC) levels, and linked the relationship between soil respiration and soil temperature, soil moisture, SOC and slope position. Experiments were carried out in the plots of S type slopes include five different soil organic carbon levels in the Loess Hilly Region. The S type slopes were divided into control area at the top of the slope, erosion area at the middle of the slope and deposition area at the toe of the slope. We found that soil temperature had a greater impact on soil respiration in the deposition area, whereas soil moisture had a greater impact on soil respiration in the erosion area compared among control area, erosion area and deposition area. In addition, SOC was the most important factor affecting soil respiration, which can explain soil respiration variation 54. 72%, followed by soil moisture, slope position and soil temperature, which explain soil respiration variation 18. 86% , 16. 13% and 10. 29%, respectively. Soil respiration response to erosion showed obvious on-site and off-site effects along the eroded sloping land. Soil respiration in the erosion area was reduced by 21. 14% compared with control area, and soil respiration in the deposition area was increased by 21. 93% compared with control area. Erosion effect on source and sink of carbon emission was correlated with SOC content of the eroded sloping land. When SOC content was higher than 6. 82 g.kg-1, the slope. erosion tended to be a carbon sequestration process, and when SOC content was lower than 3.03 g.kg-1, the slope erosion tended to be a process of the carbon emission source. The model could reflect the relationship between soil respiration and independent variables of soil organic carbon content, soil temperature and moisture.

  11. Dependence of soil respiration on soil temperature and soil moisture in successional forests in Southern China

    USGS Publications Warehouse

    Tang, X.-L.; Zhou, G.-Y.; Liu, S.-G.; Zhang, D.-Q.; Liu, S.-Z.; Li, J.; Zhou, C.-Y.

    2006-01-01

    The spatial and temporal variations in soil respiration and its relationship with biophysical factors in forests near the Tropic of Cancer remain highly uncertain. To contribute towards an improvement of actual estimates, soil respiration rates, soil temperature, and soil moisture were measured in three successional subtropical forests at the Dinghushan Nature Reserve (DNR) in southern China from March 2003 to February 2005. The overall objective of the present study was to analyze the temporal variations of soil respiration and its biophysical dependence in these forests. The relationships between biophysical factors and soil respiration rates were compared in successional forests to test the hypothesis that these forests responded similarly to biophysical factors. The seasonality of soil respiration coincided with the seasonal climate pattern, with high respiration rates in the hot humid season (April-September) and with low rates in the cool dry season (October-March). Soil respiration measured at these forests showed a clear increasing trend with the progressive succession. Annual mean (?? SD) soil respiration rate in the DNR forests was (9.0 ?? 4.6) Mg CO2-C/hm2per year, ranging from (6.1 ?? 3.2) Mg CO2-C/hm2per year in early successional forests to (10.7 ?? 4.9) Mg CO2-C/hm2 per year in advanced successional forests. Soil respiration was correlated with both soil temperature and moisture. The T/M model, where the two biophysical variables are driving factors, accounted for 74%-82% of soil respiration variation in DNR forests. Temperature sensitivity decreased along progressive succession stages, suggesting that advanced-successional forests have a good ability to adjust to temperature. In contrast, moisture increased with progressive succession processes. This increase is caused, in part, by abundant respirators in advanced-successional forest, where more soil moisture is needed to maintain their activities. ?? 2006 Institute of Botany, Chinese Academy of

  12. Soil texture drives responses of soil respiration to precipitation pulses in the sonoran desert: Implications for climate change

    USGS Publications Warehouse

    Cable, J.M.; Ogle, K.; Williams, D.G.; Weltzin, J.F.; Huxman, T. E.

    2008-01-01

    Climate change predictions for the desert southwestern U.S. are for shifts in precipitation patterns. The impacts of climate change may be significant, because desert soil processes are strongly controlled by precipitation inputs ('pulses') via their effect on soil water availability. This study examined the response of soil respiration-an important biological process that affects soil carbon (C) storage-to variation in pulses representative of climate change scenarios for the Sonoran Desert. Because deserts are mosaics of different plant cover types and soil textures-which create patchiness in soil respiration-we examined how these landscape characteristics interact to affect the response of soil respiration to pulses. Pulses were applied to experimental plots of bare and vegetated soil on contrasting soil textures typical of Sonoran Desert grasslands. The data were analyzed within a Bayesian framework to: (1) determine pulse size and antecedent moisture (soil moisture prior to the pulse) effects on soil respiration, (2) quantify soil texture (coarse vs. fine) and cover type (bare vs. vegetated) effects on the response of soil respiration and its components (plant vs. microbial) to pulses, and (3) explore the relationship between long-term variation in pulse regimes and seasonal soil respiration. Regarding objective (1), larger pulses resulted in higher respiration rates, particularly from vegetated fine-textured soil, and dry antecedent conditions amplified respiration responses to pulses (wet antecedent conditions dampened the pulse response). Regarding (2), autotrophic (plant) activity was a significant source (???60%) of respiration and was more sensitive to pulses on coarse- versus fine-textured soils. The sensitivity of heterotrophic (microbial) respiration to pulses was highly dependent on antecedent soil water. Regarding (3), seasonal soil respiration was predicted to increase with both growing season precipitation and mean pulse size (but only for pulses

  13. Effects of soil warming and nitrogen addition on soil respiration in a New Zealand tussock grassland.

    PubMed

    Graham, Scott L; Hunt, John E; Millard, Peter; McSeveny, Tony; Tylianakis, Jason M; Whitehead, David

    2014-01-01

    Soil respiration (RS) represents a large terrestrial source of CO2 to the atmosphere. Global change drivers such as climate warming and nitrogen deposition are expected to alter the terrestrial carbon cycle with likely consequences for RS and its components, autotrophic (RA) and heterotrophic respiration (RH). Here we investigate the impacts of a 3°C soil warming treatment and a 50 kg ha(-1) y(-1) nitrogen addition treatment on RS, RH and their respective seasonal temperature responses in an experimental tussock grassland. Average respiration in untreated soils was 0.96±0.09 μmol m(-2) s(-1) over the course of the experiment. Soil warming and nitrogen addition increased RS by 41% and 12% respectively. These treatment effects were additive under combined warming and nitrogen addition. Warming increased RH by 37% while nitrogen addition had no effect. Warming and nitrogen addition affected the seasonal temperature response of RS by increasing the basal rate of respiration (R10) by 14% and 20% respectively. There was no significant interaction between treatments for R10. The treatments had no impact on activation energy (E0). The seasonal temperature response of RH was not affected by either warming or nitrogen addition. These results suggest that the additional CO2 emissions from New Zealand tussock grassland soils as a result of warming-enhanced RS constitute a potential positive feedback to rising atmospheric CO2 concentration.

  14. Plant community structure regulates responses of prairie soil respiration to decadal experimental warming.

    PubMed

    Xu, Xia; Shi, Zheng; Li, Dejun; Zhou, Xuhui; Sherry, Rebecca A; Luo, Yiqi

    2015-10-01

    Soil respiration is recognized to be influenced by temperature, moisture, and ecosystem production. However, little is known about how plant community structure regulates responses of soil respiration to climate change. Here, we used a 13-year field warming experiment to explore the mechanisms underlying plant community regulation on feedbacks of soil respiration to climate change in a tallgrass prairie in Oklahoma, USA. Infrared heaters were used to elevate temperature about 2 °C since November 1999. Annual clipping was used to mimic hay harvest. Our results showed that experimental warming significantly increased soil respiration approximately from 10% in the first 7 years (2000-2006) to 30% in the next 6 years (2007-2012). The two-stage warming stimulation of soil respiration was closely related to warming-induced increases in ecosystem production over the years. Moreover, we found that across the 13 years, warming-induced increases in soil respiration were positively affected by the proportion of aboveground net primary production (ANPP) contributed by C3 forbs. Functional composition of the plant community regulated warming-induced increases in soil respiration through the quantity and quality of organic matter inputs to soil and the amount of photosynthetic carbon (C) allocated belowground. Clipping, the interaction of clipping with warming, and warming-induced changes in soil temperature and moisture all had little effect on soil respiration over the years (all P > 0.05). Our results suggest that climate warming may drive an increase in soil respiration through altering composition of plant communities in grassland ecosystems. PMID:25846478

  15. Hydrological controls on heterotrophic soil respiration across an agricultural landscape

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water availability is an important determinant of variation in soil respiration, but a consistent relationship between soil water and the relative flux rate of carbon dioxide across different soil types remains elusive. Using large undisturbed soil columns (N = 12), we evaluated soil water controls...

  16. Changes in soil respiration components and their specific respiration along three successional forests in the subtropics

    DOE PAGES

    Han, Tianfeng; Liu, Juxiu; Wang, Gangsheng; Huang, Wenjuan; Zhou, Guoyi

    2016-01-16

    1.Understanding how soil respiration components change with forest succession is critical for modelling and predicting soil carbon (C) processes and its sequestration below-ground. The specific respiration (a ratio of respiration to biomass) is increasingly being used as an indicator of forest succession conceptually based on Odum's theory of ecosystem development. However, the hypothesis that specific soil respiration declines with forest succession remains largely untested. 2.We used a trenching method to partition soil respiration into heterotrophic respiration and autotrophic respiration (RH and RA) and then evaluated the specific RH and specific RA in three successional forests in subtropical China. 3.Our resultsmore » showed a clear seasonality in the influence of forest succession on RH, with no significant differences among the three forests in the dry season but a higher value in the old-growth forest than the other two forests in the wet season. RA in the old-growth forest tended to be the highest among the three forests. Both the specific RH and specific RA decreased with the progressive maturity of three forests. 4.Lastly, our results highlight the importance of forest succession in determining the variation of RH in different seasons. With forest succession, soil microbes and plant roots become more efficient to conserve C resources, which would result in a greater proportion of C retained in soils.« less

  17. Vegetation types alter soil respiration and its temperature sensitivity at the field scale in an estuary wetland.

    PubMed

    Han, Guangxuan; Xing, Qinghui; Luo, Yiqi; Rafique, Rashad; Yu, Junbao; Mikle, Nate

    2014-01-01

    Vegetation type plays an important role in regulating the temporal and spatial variation of soil respiration. Therefore, vegetation patchiness may cause high uncertainties in the estimates of soil respiration for scaling field measurements to ecosystem level. Few studies provide insights regarding the influence of vegetation types on soil respiration and its temperature sensitivity in an estuary wetland. In order to enhance the understanding of this issue, we focused on the growing season and investigated how the soil respiration and its temperature sensitivity are affected by the different vegetation (Phragmites australis, Suaeda salsa and bare soil) in the Yellow River Estuary. During the growing season, there were significant linear relationships between soil respiration rates and shoot and root biomass, respectively. On the diurnal timescale, daytime soil respiration was more dependent on net photosynthesis. A positive correlation between soil respiration and net photosynthesis at the Phragmites australis site was found. There were exponential correlations between soil respiration and soil temperature, and the fitted Q10 values varied among different vegetation types (1.81, 2.15 and 3.43 for Phragmites australis, Suaeda salsa and bare soil sites, respectively). During the growing season, the mean soil respiration was consistently higher at the Phragmites australis site (1.11 µmol CO2 m(-2) s(-1)), followed by the Suaeda salsa site (0.77 µmol CO2 m(-2) s(-1)) and the bare soil site (0.41 µmol CO2 m(-2) s(-1)). The mean monthly soil respiration was positively correlated with shoot and root biomass, total C, and total N among the three vegetation patches. Our results suggest that vegetation patchiness at a field scale might have a large impact on ecosystem-scale soil respiration. Therefore, it is necessary to consider the differences in vegetation types when using models to evaluate soil respiration in an estuary wetland.

  18. Soil respiration flux in northern coastal temperate rainforest ecosystems

    NASA Astrophysics Data System (ADS)

    D'Amore, D. V.; Nay, S. M.; Edwards, R.; Valentine, D. W.; Hood, E. W.

    2009-12-01

    Forest carbon budgets are of increasing concern because of their linkages with changing climate. The potential source strength of northern forested ecosystems is of great interest due to the large carbon stock of these systems, especially the extensive peatlands. Where very few long-term measurements of soil carbon cycles have been made, such as the North Pacific coastal temperate margin, peatlands have potentially large but largely unknown source strengths, particularly through soil respiration. The easily and widely measured factors that influence the metabolism of plants and microorganisms in soils, such as temperature, moisture and substrate quality, must be coupled with a network of plot-scale measurements of soil respiration fluxes in this region in order to produce reasonable models of soil respiration flux across gradients of climate, vegetation and soil types. We designed a study to address this issue and measured soil respiration across a hydrologic gradient to quantify the influence of soil temperature and moisture on the magnitude and seasonality of carbon fluxes in the coastal temperate rainforest biome. Replicated study sites were established in three common ecosystem types (peatlands, forested wetlands, and upland forest) within three coastal watersheds. In total, nine sites of the three ecosystem types were measured at monthly intervals during the snow-free period between May and November for two years. Soil respiration fluxes during the six-month measurement period were used to construct a respiration flux model for each landscape type. Soil respiration fluxes followed the seasonal temperature pattern in all ecosystem types and also varied with soil saturation as well in uplands. Temperature dependent models of soil respiration flux were best fit to intermediate drainage conditions in forested wetlands and explained up to 85% of the variation in this ecosystem type. Modeled soil respiration estimates were better at low temperatures with high water

  19. Soil respiration flux in northern coastal temperate rainforest ecosystems

    NASA Astrophysics Data System (ADS)

    D'Amore, David; Nay, S. Mark; Edwards, Richard; Valentine, David; Hood, Eran

    2010-05-01

    Forest carbon budgets are of increasing concern because of their linkages with changing climate. The potential source strength of northern forested ecosystems is of great interest due to the large carbon stock of these systems, especially the extensive peatlands. Where very few long-term measurements of soil carbon cycles have been made, such as the North Pacific coastal temperate margin, peatlands have potentially large but largely unknown source strengths, particularly through soil respiration. The easily and widely measured factors that influence the metabolism of plants and microorganisms in soils, such as temperature, moisture and substrate quality, must be coupled with a network of plot-scale measurements of soil respiration fluxes in this region in order to produce reasonable models of soil respiration flux across gradients of climate, vegetation and soil types. We designed a study to address this issue and measured soil respiration across a hydrologic gradient to quantify the influence of soil temperature and moisture on the magnitude and seasonality of carbon fluxes in the coastal temperate rainforest biome. Replicated study sites were established in three common ecosystem types (peatlands, forested wetlands, and upland forest) within three coastal watersheds. In total, nine sites of the three ecosystem types were measured at monthly intervals during the snow-free period between May and November for two years. Soil respiration fluxes during the six-month measurement period were used to construct a respiration flux model for each landscape type. Soil respiration fluxes followed the seasonal temperature pattern in all ecosystem types and also varied with soil saturation as well in uplands. Temperature dependent models of soil respiration flux were best fit to intermediate drainage conditions in forested wetlands and explained up to 85% of the variation in this ecosystem type. Modeled soil respiration estimates were better at low temperatures with high water

  20. Influence of disturbance on soil respiration in biologically crusted soil during the dry season.

    PubMed

    Feng, Wei; Zhang, Yu-qing; Wu, Bin; Zha, Tian-shan; Jia, Xin; Qin, Shu-gao; Shao, Chen-xi; Liu, Jia-bin; Lai, Zong-rui; Fa, Ke-yu

    2013-01-01

    Soil respiration (Rs) is a major pathway for carbon cycling and is a complex process involving abiotic and biotic factors. Biological soil crusts (BSCs) are a key biotic component of desert ecosystems worldwide. In desert ecosystems, soils are protected from surface disturbance by BSCs, but it is unknown whether Rs is affected by disturbance of this crust layer. We measured Rs in three types of disturbed and undisturbed crusted soils (algae, lichen, and moss), as well as bare land from April to August, 2010, in Mu Us desert, northwest China. Rs was similar among undisturbed soils but increased significantly in disturbed moss and algae crusted soils. The variation of Rs in undisturbed and disturbed soil was related to soil bulk density. Disturbance also led to changes in soil organic carbon and fine particles contents, including declines of 60-70% in surface soil C and N, relative to predisturbance values. Once BSCs were disturbed, Q 10 increased. Our findings indicate that a loss of BSCs cover will lead to greater soil C loss through respiration. Given these results, understanding the disturbance sensitivity impact on Rs could be helpful to modify soil management practices which promote carbon sequestration.

  1. [Differences in soil respiration between cropland and grassland ecosystems and factors influencing soil respiration on the Loess Plateau].

    PubMed

    Zhou, Xiao-Gang; Zhang, Yan-Jun; Nan, Ya-Fang; Liu, Qing-Fang; Guo, Sheng-Li

    2013-03-01

    Understanding the effect of land-use change on soil respiration rates becomes critical in predicting soil carbon cycling under conversion of arable into grassland on the Loess Plateau. From July 2010 to December 2011, CO2 efflux from the soil surface was measured between 08:00 to 10:00 am in clear days by a Licor-8100 closed chamber system (Li-COR, Lincoln, NE, US). Also, soil temperature and soil moisture at the 5-cm depth was measured using a Li-Cor thermocouple and a hand-held frequency-domain reflectometer (ML2x, Delta-T Devices Ltd, UK) at each PVC collar, respectively. We found marked differences (P < 0.05) in soil respiration related to different land-use: the mean cropland soil respiration [1.35 micromol x (m2 x s)(-1)] was 24% (P < 0.05) less than the paired grassland soil respiration [1.67 micromol x (m2 x s)(-1)] (P < 0.05) during the period of experiment and the cumulative CO2-C emissions in grassland (856 g x m(-2)) was 23% (P < 0.05) higher than that in cropland (694 g x m(-2)). Soil moisture from 0-5 cm depth was much drier in cropland and significantly different between cropland and grassland except for winter. However, there were no clear relationships between soil moisture and soil respiration. Soil temperature at 5-cm depth was 2.5 degress C higher in grassland during the period of experiment (P < 0.05). Regression of soil temperature vs. soil respiration indicated significant exponential relationships both in grassland and cropland. Besides, there were intrinsic differences in response of soil respiration to temperature between the cropland and grassland ecosystems: grassland and cropland respiration response was significantly different at the alpha = 0.05 level, also expressed by a higher temperature sensitivity of soil respiration (Q10) in cropland (2.30) relative to grassland (1.74). Soil temperature of cropland and grassland can explain 79% of the variation in the soil respiration in grassland, compared to 82% in cropland. Therefore, land

  2. [Differences in soil respiration between cropland and grassland ecosystems and factors influencing soil respiration on the Loess Plateau].

    PubMed

    Zhou, Xiao-Gang; Zhang, Yan-Jun; Nan, Ya-Fang; Liu, Qing-Fang; Guo, Sheng-Li

    2013-03-01

    Understanding the effect of land-use change on soil respiration rates becomes critical in predicting soil carbon cycling under conversion of arable into grassland on the Loess Plateau. From July 2010 to December 2011, CO2 efflux from the soil surface was measured between 08:00 to 10:00 am in clear days by a Licor-8100 closed chamber system (Li-COR, Lincoln, NE, US). Also, soil temperature and soil moisture at the 5-cm depth was measured using a Li-Cor thermocouple and a hand-held frequency-domain reflectometer (ML2x, Delta-T Devices Ltd, UK) at each PVC collar, respectively. We found marked differences (P < 0.05) in soil respiration related to different land-use: the mean cropland soil respiration [1.35 micromol x (m2 x s)(-1)] was 24% (P < 0.05) less than the paired grassland soil respiration [1.67 micromol x (m2 x s)(-1)] (P < 0.05) during the period of experiment and the cumulative CO2-C emissions in grassland (856 g x m(-2)) was 23% (P < 0.05) higher than that in cropland (694 g x m(-2)). Soil moisture from 0-5 cm depth was much drier in cropland and significantly different between cropland and grassland except for winter. However, there were no clear relationships between soil moisture and soil respiration. Soil temperature at 5-cm depth was 2.5 degress C higher in grassland during the period of experiment (P < 0.05). Regression of soil temperature vs. soil respiration indicated significant exponential relationships both in grassland and cropland. Besides, there were intrinsic differences in response of soil respiration to temperature between the cropland and grassland ecosystems: grassland and cropland respiration response was significantly different at the alpha = 0.05 level, also expressed by a higher temperature sensitivity of soil respiration (Q10) in cropland (2.30) relative to grassland (1.74). Soil temperature of cropland and grassland can explain 79% of the variation in the soil respiration in grassland, compared to 82% in cropland. Therefore, land

  3. Biochar has no effect on soil respiration across Chinese agricultural soils.

    PubMed

    Liu, Xiaoyu; Zheng, Jufeng; Zhang, Dengxiao; Cheng, Kun; Zhou, Huimin; Zhang, Afeng; Li, Lianqing; Joseph, Stephen; Smith, Pete; Crowley, David; Kuzyakov, Yakov; Pan, Genxing

    2016-06-01

    Biochar addition to soil has been widely accepted as an option to enhance soil carbon sequestration by introducing recalcitrant organic matter. However, it remains unclear whether biochar will negate the net carbon accumulation by increasing carbon loss through CO2 efflux from soil (soil respiration). The objectives of this study were to address: 1) whether biochar addition increases soil respiration; and whether biochar application rate and biochar type (feedstock and pyrolyzing system) affect soil respiration. Two series of field experiments were carried out at 8 sites representing the main crop production areas in China. In experiment 1, a single type of wheat straw biochar was amended at rates of 0, 20 and 40 tha(-1) in four rice paddies and three dry croplands. In experiment 2, four types of biochar (varying in feedstock and pyrolyzing system) were amended at rates of 0 and 20 tha(-1) in a rice paddy under rice-wheat rotation. Results showed that biochar addition had no effect on CO2 efflux from soils consistently across sites, although it increased topsoil organic carbon stock by 38% on average. Meanwhile, CO2 efflux from soils amended with 40 t of biochar did not significantly higher than soils amended with 20 t of biochar. While the biochars used in Experiment 2 had different carbon pools and physico-chemical properties, they had no effect on soil CO2 efflux. The soil CO2 efflux following biochar addition could be hardly explained by the changes in soil physic-chemical properties and in soil microbial biomass. Thus, we argue that biochar will not negate the net carbon accumulation by increasing carbon loss through CO2 efflux in agricultural soils. PMID:26950640

  4. Biochar has no effect on soil respiration across Chinese agricultural soils.

    PubMed

    Liu, Xiaoyu; Zheng, Jufeng; Zhang, Dengxiao; Cheng, Kun; Zhou, Huimin; Zhang, Afeng; Li, Lianqing; Joseph, Stephen; Smith, Pete; Crowley, David; Kuzyakov, Yakov; Pan, Genxing

    2016-06-01

    Biochar addition to soil has been widely accepted as an option to enhance soil carbon sequestration by introducing recalcitrant organic matter. However, it remains unclear whether biochar will negate the net carbon accumulation by increasing carbon loss through CO2 efflux from soil (soil respiration). The objectives of this study were to address: 1) whether biochar addition increases soil respiration; and whether biochar application rate and biochar type (feedstock and pyrolyzing system) affect soil respiration. Two series of field experiments were carried out at 8 sites representing the main crop production areas in China. In experiment 1, a single type of wheat straw biochar was amended at rates of 0, 20 and 40 tha(-1) in four rice paddies and three dry croplands. In experiment 2, four types of biochar (varying in feedstock and pyrolyzing system) were amended at rates of 0 and 20 tha(-1) in a rice paddy under rice-wheat rotation. Results showed that biochar addition had no effect on CO2 efflux from soils consistently across sites, although it increased topsoil organic carbon stock by 38% on average. Meanwhile, CO2 efflux from soils amended with 40 t of biochar did not significantly higher than soils amended with 20 t of biochar. While the biochars used in Experiment 2 had different carbon pools and physico-chemical properties, they had no effect on soil CO2 efflux. The soil CO2 efflux following biochar addition could be hardly explained by the changes in soil physic-chemical properties and in soil microbial biomass. Thus, we argue that biochar will not negate the net carbon accumulation by increasing carbon loss through CO2 efflux in agricultural soils.

  5. [Soil respiration dynamics and its controlling factors of typical vegetation communities on meadow steppes in the western Songnen Plain].

    PubMed

    Wang, Ming; Liu, Xing-Tu; Li, Xiu-Jun; Zhang, Ji-Tao; Wang, Guo-Dong; Lu, Xin-Rui; Li, Xiao-Yu

    2014-01-01

    In order to accurately explore the soil respiration dynamics and its controlling factors of typical vegetation types in the western Songnen Plain, soil respiration rates of Chloris virgata, Puccinellia distans, Phragmites australis and Leymus chinensis communities were measured. The results showed that the diurnal curves of soil respiration rates of the four vegetation communities had simple peak values, which appeared at 11:00-15:00, and the valley values occurred at 21:00-1:00 or 3:00-5:00. The seasonal dynamic patterns of their soil respiration rates were similar, with the maximum (3.21-4.84 micromol CO2 x m(-2) x s(-1)) occurring in July and August and the minimum (0.46-1.51 micromol CO2 x m(-2) x s(-1)) in October. The soil respiration rates of the four vegetation communities had significant exponential correlations with ambient air temperature and soil temperature. Soil moisture, however, only played an important role in affecting the soil respiration rate of C. virgata community while air humidity near the soil surface was significantly correlated with the soil respiration rates of P. australis and L. chinensis communities. The soil salt contents seriously constrained the CO2 dioxide emission, and the soil pH, electrical conductivity (EC), exchangeable sodium percentage (ESP) could explain 87%-91% spatial variations of the soil respiration rate.

  6. Dynamic Responses of Root, Mycorrhizal and Soil Heterotrophic Respiration to Temperature Increases in an Arid System of Southeast Spain.

    NASA Astrophysics Data System (ADS)

    Estruch, C.; Pugnaire, F. I.

    2014-12-01

    Mycorrhizal and heterotrophic respiration may represent up to 80% of total soil respiration in temperate environments; however little is known about arid environments where the dynamics of carbon cycling is less known. To improve models of CO2 efflux to the atmosphere in these environments it is necessary to quantify the contribution of soil components (roots, mycorrhizas and heterotrophic respiration) to soil respiration and their response to temperature increases. We settled up a soil partitioning experiment in December 2013 to address this topic. Using a mesh-collar design we quantified soil respiration of the tree main components (roots, mycorrhiza and heterotrophic respiration) in a Mediterranean arid location dominated by the shrub Rethama sphaerocarpa under two temperature regimes, an increased air temperature using open-top chambers (OTC) and a control. For the firths 6 months of measurements, we recorded a decrease in annual species cover with increased temperature; total soil respiration varied between treatments, being higher in the control treatment while, contrary to our expectations, mycorrhizal and soil heterotrophic respiration did not vary between treatments. When looking at the relative contribution of the different soil components, the treatment enclosing both mycorrhizal and soil heterotrophic respiration represented more than half the total soil respiration. These results show that temperature affects total soil respiration and that, in our case, mycorrhizal and soil heterotrophic community were not major drivers of soil respiration responses to temperature. However, these data correspond to an abnormal dry period and data to be collected during the wet season would help us to better understand the contribution of the different soil components to temperature increases in arid environments.

  7. Effects of Experimental Drought on Soil Respiration and Radiocarbon Efflux from a Temperate Forest Soil

    NASA Astrophysics Data System (ADS)

    Borken, W.; Savage, K.; Davidson, E. A.; Trumbore, S. E.

    2002-12-01

    Soil respiration is affected by the water content of both mineral soil and organic horizons. A throughfall exclusion experiment was established at the Harvard Forest in central Massachusetts to quantify the importance of this variation. Weekly measurements of soil respiration began in the spring of 2001, with 4 manual flux chambers installed in each of 6 plots (5 x 5 m). In July 2001, sub-canopy roofs with translucent plastic panels were installed in 3 of the plots, while the other 3 control plots were left open. Temperature probes, TDR probes, and gas tubes were buried at 4 depths in each plot. DC half-bridges for measuring water content of organic material were installed in the O horizons. The roofs were removed in the autumn to allow leaf-fall and snowfall and were reinstalled in the spring of 2002. Hourly automated flux measurements, with one chamber in each of the 6 plots, were also started in the spring of 2002. Radiocarbon contents of CO2 emissions and concentrations within the soil have been measured periodically. Soil respiration rates were similar in control and treatment plots throughout June 2001, but once throughfall exclusion began in July, the fluxes declined in the exclusion plots. During the 84 days of 2001 that the roofs were in place, 168 mm of throughfall was diverted, and the cumulative soil respiration was 30% lower in exclusion plots compared to control plots (241 and 341 g C m-2, respectively). The automated chamber system revealed an increase in soil respiration in the control plots within minutes of a precipitation event. Soil respiration declined to pre-wetting values at the same time that the litter layer dried, about 48 hours after wetting. The Δ14CO2 from soil respiration ranged from 95 to 141‰ in the control plots and from 88 to 263‰ in the exclusion plots. The Δ14CO2 from root respiration and recently fixed carbon (within 1 year) should be 77‰ (the value of the atmosphere in 2001), so the observed values indicate that the

  8. Soil Respiration Hotspots in Temperate Tidal Restored and Natural Wetlands

    NASA Astrophysics Data System (ADS)

    Scott, M.; Schafer, K. V.

    2015-12-01

    Whether a wetland is a carbon dioxide sink or source is dependent on the balance of photosynthesis and ecosystem respiration. As temperature is increasing, respiration may accelerate over photosynthesis, yet the dynamics in tidal temperate wetlands are not clear as the tidal influence impact respiration egress of the soil. Here, we investigated soil respiration of two different microsites in each a natural and a restored wetland over a range of temperature and water level conditions over the growing season. Soil respiration increased with incoming tide and was lowest under water-inundated conditions. Mudflat microsites tended to have higher soil respiration than vegetated areas, indicating sufficiently high carbon input into non-vegetated areas for high respiratory fluxes. Whereby Spartina alterniflora microsites exhibited on average lower soil respiration fluxes of about 13 micromol m-2 s-1, Spartina patens exhibited higher fluxes at about 38 micromol m2 s-1 with Phragmites australis intermediate soil respiratory fluxes. Largest spatial variation was observed for mudflat microsites.

  9. On the relative roles of hydrology, salinity, temperature, and root productivity in controlling soil respiration from coastal swamps (freshwater)

    USGS Publications Warehouse

    Krauss, Ken W.; Whitbeck, Julie L.; Howard, Rebecca J.

    2012-01-01

    Background and aims Soil CO2 emissions can dominate gaseous carbon losses from forested wetlands (swamps), especially those positioned in coastal environments. Understanding the varied roles of hydroperiod, salinity, temperature, and root productivity on soil respiration is important in discerning how carbon balances may shift as freshwater swamps retreat inland with sea-level rise and salinity incursion, and convert to mixed communities with marsh plants. Methods We exposed soil mesocosms to combinations of permanent flooding, tide, and salinity, and tracked soil respiration over 2 1/2 growing seasons. We also related these measurements to rates from field sites along the lower Savannah River, Georgia, USA. Soil temperature and root productivity were assessed simultaneously for both experiments. Results Soil respiration from mesocosms (22.7-1678.2 mg CO2 m-2 h-1) differed significantly among treatments during four of the seven sampling intervals, where permanently flooded treatments contributed to low rates of soil respiration and tidally flooded treatments sometimes contributed to higher rates. Permanent flooding reduced the overall capacity for soil respiration as soils warmed. Salinity did reduce soil respiration at times in tidal treatments, indicating that salinity may affect the amount of CO2 respired with tide more strongly than under permanent flooding. However, soil respiration related greatest to root biomass (mesocosm) and standing root length (field); any stress reducing root productivity (incl. salinity and permanent flooding) therefore reduces soil respiration. Conclusions Overall, we hypothesized a stronger, direct role for salinity on soil respiration, and found that salinity effects were being masked by varied capacities for increases in respiration with soil warming as dictated by hydrology, and the indirect influence that salinity can have on plant productivity.

  10. [Microbial response mechanism for drying and rewetting effect on soil respiration in grassland ecosystem: a review].

    PubMed

    He, Yun-Long; Qi, Yu-Chun; Dong, Yun-She; Peng, Qin; Sun, Liang-Jie; Jia, Jun-Qiang; Guo, Shu-Fang; Yan, Zhong-Qing

    2014-11-01

    As one of the most important and wide distribution community type among terrestrial ecosystems, grassland ecosystem plays a critical role in the global carbon cycles and climate regulation. China has extremely rich grassland resources, which have a huge carbon sequestration potential and are an important part of the global carbon cycle. Drying and rewetting is a common natural phenomenon in soil, which might accelerate soil carbon mineralization process, increase soil respiration and exert profound influence on microbial activity and community structure. Under the background of the global change, the changes in rainfall capacity, strength and frequency would inevitably affect soil drying and wetting cycles, and thus change the microbial activity and community structure as well as soil respiration, and then exert important influence on global carbon budget. In this paper, related references in recent ten years were reviewed. The source of soil released, the trend of soil respiration over time and the relationship between soil respiration and microbial biomass, microbial activity and microbial community structure during the processes of dry-rewetting cycle were analyzed and summarized, in order to better understand the microbial response mechanism for drying and rewetting effecting on soil respiration in grassland ecosystem, and provide a certain theoretical basis for more accurate evaluation and prediction of future global carbon balance of terrestrial ecosystems and climate change.

  11. Plant community composition, not diversity, regulates soil respiration in grasslands.

    PubMed

    Johnson, David; Phoenix, Gareth K; Grime, J Philip

    2008-08-23

    Soil respiration is responsible for recycling considerable quantities of carbon from terrestrial ecosystems to the atmosphere. There is a growing body of evidence that suggests that the richness of plants in a community can have significant impacts on ecosystem functioning, but the specific influences of plant species richness (SR), plant functional-type richness and plant community composition on soil respiration rates are unknown. Here we use 10-year-old model plant communities, comprising mature plants transplanted into natural non-sterile soil, to determine how the diversity and composition of plant communities influence soil respiration rates. Our analysis revealed that soil respiration was driven by plant community composition and that there was no significant effect of biodiversity at the three levels tested (SR, functional group and species per functional group). Above-ground plant biomass and root density were included in the analysis as covariates and found to have no effect on soil respiration. This finding is important, because it suggests that loss of particular species will have the greatest impact on soil respiration, rather than changes in biodiversity per se.

  12. A global database of soil respiration data

    NASA Astrophysics Data System (ADS)

    Bond-Lamberty, B.; Thomson, A.

    2010-02-01

    Soil respiration - RS, the flux of autotropically- and heterotrophically-generated CO2 from the soil to the atmosphere - remains the least well-constrained component of the terrestrial C cycle. Here we introduce the SRDB database, a near-universal compendium of published RS data, and make it available to the scientific community both as a traditional static archive and as a dynamic community database that will be updated over time by interested users. The database encompasses all published studies that report one of the following data measured in the field (not laboratory): annual RS, mean seasonal RS, a seasonal or annual partitioning of RS into its sources fluxes, RS temperature response (Q10), or RS at 10 °C. Its orientation is thus to seasonal and annual fluxes, not shorter-term or chamber-specific measurements. To date, data from 818 studies have been entered into the database, constituting 3379 records. The data span the measurement years 1961-2007 and are dominated by temperate, well-drained forests. We briefly examine some aspects of the SRDB data - mean annual RS fluxes and their correlation with other carbon fluxes, RS variability, temperature sensitivities, and the partitioning of RS source flux - and suggest some potential lines of research that could be explored using these data. The SRDB database described here is available online in a permanent archive as well as via a project-hosting repository; the latter source leverages open-source software technologies to encourage wider participation in the database's future development. Ultimately, we hope that the updating of, and corrections to, the SRDB will become a shared project, managed by the users of these data in the scientific community.

  13. A global database of soil respiration data

    NASA Astrophysics Data System (ADS)

    Bond-Lamberty, B.; Thomson, A.

    2010-06-01

    Soil respiration - RS, the flux of CO2 from the soil to the atmosphere - is probably the least well constrained component of the terrestrial carbon cycle. Here we introduce the SRDB database, a near-universal compendium of published RS data, and make it available to the scientific community both as a traditional static archive and as a dynamic community database that may be updated over time by interested users. The database encompasses all published studies that report one of the following data measured in the field (not laboratory): annual RS, mean seasonal RS, a seasonal or annual partitioning of RS into its sources fluxes, RS temperature response (Q10), or RS at 10 °C. Its orientation is thus to seasonal and annual fluxes, not shorter-term or chamber-specific measurements. To date, data from 818 studies have been entered into the database, constituting 3379 records. The data span the measurement years 1961-2007 and are dominated by temperate, well-drained forests. We briefly examine some aspects of the SRDB data - its climate space coverage, mean annual RS fluxes and their correlation with other carbon fluxes, RS variability, temperature sensitivities, and the partitioning of RS source flux - and suggest some potential lines of research that could be explored using these data. The SRDB database is available online in a permanent archive as well as via a project-hosting repository; the latter source leverages open-source software technologies to encourage wider participation in the database's future development. Ultimately, we hope that the updating of, and corrections to, the SRDB will become a shared project, managed by the users of these data in the scientific community.

  14. Temporal changes of soil respiration under different tree species.

    PubMed

    Akburak, Serdar; Makineci, Ender

    2013-04-01

    Soil respiration rates were measured monthly (from April 2007 to March 2008) under four adjacent coniferous plantation sites [Oriental spruce (Picea orientalis L.), Austrian pine (Pinus nigra Arnold), Turkish fir (Abies bornmulleriana L.), and Scots pine (Pinus sylvestris L.)] and adjacent natural Sessile oak forest (Quercus petraea L.) in Belgrad Forest-Istanbul/Turkey. Also, soil moisture, soil temperature, and fine root biomass were determined to identify the underlying environmental variables among sites which are most likely causing differences in soil respiration. Mean annual soil moisture was determined to be between 6.3 % and 8.1 %, and mean annual temperature ranged from 13.0°C to 14.2°C under all species. Mean annual fine root biomass changed between 368.09 g/m(2) and 883.71 g/m(2) indicating significant differences among species. Except May 2007, monthly soil respiration rates show significantly difference among species. However, focusing on tree species, differences of mean annual respiration rates did not differ significantly. Mean annual soil respiration ranged from 0.56 to 1.09 g C/m(2)/day. The highest rates of soil respiration reached on autumn months and the lowest rates were determined on summer season. Soil temperature, soil moisture, and fine root biomass explain mean annual soil respiration rates at the highest under Austrian pine (R (2) = 0.562) and the lowest (R (2) = 0.223) under Turkish fir.

  15. Soil respiration is not limited by reductions in microbial biomass during long-term soil incubations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Declining rates of soil respiration are reliably observed during long-term laboratory incubations, but the cause is uncertain. We explored different controls on soil respiration during long-term soil incubations. Following a 707 day incubation (30 C) of soils from cultivated and forested plots at Ke...

  16. ESTIMATING ROOT RESPIRATION IN SPRUCE AND BEECH: DECREASES IN SOIL RESPIRATION FOLLOWING GIRDLING

    EPA Science Inventory

    A study was undertaken to follow seasonal fluxes of CO2 from soil and to estimate the contribution of autotrophic (root + mycorrhizal) to total soil respiration (SR) in a mixed stand of European beech (Fagus sylvatica) and Norway spruce (Picea abies) near Freising, Germany. Matu...

  17. Response of soil respiration to experimental warming and precipitation manipulation in a northern Great Plains grassland

    NASA Astrophysics Data System (ADS)

    Flanagan, L. B.; Sharp, E. J.; Letts, M. G.

    2012-12-01

    The interacting effects of altered temperature and precipitation are expected to have significant consequences for ecosystem net carbon storage. Here we report the results of an experiment that evaluated the effects of elevated temperature and altered precipitation, alone and in combination, on plant biomass production and soil respiration rates in a northern Great Plains grassland, near Lethbridge, Alberta Canada. Open-top chambers and rain shelters were used to establish an experiment with two temperature treatments (warmed and control), each combined with three precipitation treatments (minus 50%, ambient (no manipulation), and plus 50%). Our objectives were to determine the sensitivity of plant biomass production and soil respiration to temperature and moisture manipulations, and to test for direct and indirect effects of the environmental changes on soil respiration rates. The experimental manipulations resulted primarily in a significant increase in air temperature in the warmed treatment. There were no significant treatment effects on soil moisture content. Aboveground biomass was not significantly affected by the experimental manipulations, but the warmed plots of the ambient precipitation treatment showed an increase in root biomass relative to the control plots. The warmed treatment increased the cumulative loss of carbon in soil respiration by approximately 400 g C m-2 compared to the control during July-September. This higher soil respiration rate was not directly caused by differences among treatments in soil temperature or soil moisture, but was likely an indirect result of increased carbon substrate availability in the warmed relative to the control treatment.

  18. Factors affecting soil cohesion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil erodibility is a measure of a soil’s resistance against erosive forces and is affected by both intrinsic (or inherent) soil property and the extrinsic condition at the time erodibility measurement is made. Since soil erodibility is usually calculated from results obtained from erosion experimen...

  19. Soil Respiration in Relation to Photosynthesis of Quercus mongolica Trees at Elevated CO2

    PubMed Central

    Zhou, Yumei; Li, Mai-He; Cheng, Xu-Bing; Wang, Cun-Guo; Fan, A-Nan; Shi, Lian-Xuan; Wang, Xiu-Xiu; Han, Shijie

    2010-01-01

    Knowledge of soil respiration and photosynthesis under elevated CO2 is crucial for exactly understanding and predicting the carbon balance in forest ecosystems in a rapid CO2-enriched world. Quercus mongolica Fischer ex Ledebour seedlings were planted in open-top chambers exposed to elevated CO2 (EC = 500 µmol mol−1) and ambient CO2 (AC = 370 µmol mol−1) from 2005 to 2008. Daily, seasonal and inter-annual variations in soil respiration and photosynthetic assimilation were measured during 2007 and 2008 growing seasons. EC significantly stimulated the daytime soil respiration by 24.5% (322.4 at EC vs. 259.0 mg CO2 m−2 hr−1 at AC) in 2007 and 21.0% (281.2 at EC vs. 232.6 mg CO2 m−2 hr−1 at AC) in 2008, and increased the daytime CO2 assimilation by 28.8% (624.1 at EC vs. 484.6 mg CO2 m−2 hr−1 at AC) across the two growing seasons. The temporal variation in soil respiration was positively correlated with the aboveground photosynthesis, soil temperature, and soil water content at both EC and AC. EC did not affect the temperature sensitivity of soil respiration. The increased daytime soil respiration at EC resulted mainly from the increased aboveground photosynthesis. The present study indicates that increases in CO2 fixation of plants in a CO2-rich world will rapidly return to the atmosphere by increased soil respiration. PMID:21151897

  20. Fast labile carbon turnover obscures sensitivity of heterotrophic respiration from soil to temperature: A model analysis

    NASA Astrophysics Data System (ADS)

    Gu, Lianhong; Post, Wilfred M.; King, Anthony W.

    2004-03-01

    Labile carbon, although often a small fraction of soil organic carbon (SOC), significantly affects heterotrophic respiration at short timescales because of its rapid decomposition. However, in the current literature, most soil respiration measurements are interpreted without simultaneous information on labile carbon pool dynamics. Sensitivity of soil respiration to temperature is routinely derived directly from field observations, and such relationships have been used to extrapolate effects of global change (e.g., warming) on carbon emission from SOC. Here we use a multipool SOC model to demonstrate the impacts of seasonal fluctuations of labile carbon pools on interpretation of soil respiration measurements. We find that labile carbon pool sizes vary widely in response to seasonal changes in representative plant material inputs and temperature even though the model is operating at equilibrium in terms of annual means. Convolution of the dynamics of fast turnover carbon pools and temporal progression in temperature lead to misrepresentation and misinterpretation of the heterotrophic respiration-temperature relationships estimated from bulk soil CO2 exchanges. Temperature sensitivity is overestimated when the variations of labile carbon pools and temperature are in phase and underestimated when they are out of phase. Furthermore, with normally used observation time windows (weeks to a year), temperature sensitivity is more likely to be underestimated. A distortion of temperature sensitivity (Q10) from 2 (actual, sensitive dependence on temperature) to nearly 1 (false, no dependence on temperature) is shown. Applying estimated temperature sensitivity parameter back into the model considerably overestimates soil carbon storage at equilibrium. Our findings indicate that caution must be taken when soil respiration-temperature relationships are evaluated based on bulk soil observations and when sensitivity of soil respiration to temperature estimated directly under field

  1. Rates of Litter Decomposition and Soil Respiration in Relation to Soil Temperature and Water in Different-Aged Pinus massoniana Forests in the Three Gorges Reservoir Area, China

    PubMed Central

    Zeng, Lixiong; Huang, Zhilin; Lei, Jingpin; Zhou, Benzhi; Li, Maihe

    2014-01-01

    To better understand the soil carbon dynamics and cycling in terrestrial ecosystems in response to environmental changes, we studied soil respiration, litter decomposition, and their relations to soil temperature and soil water content for 18-months (Aug. 2010–Jan. 2012) in three different-aged Pinus massoniana forests in the Three Gorges Reservoir Area, China. Across the experimental period, the mean total soil respiration and litter respiration were 1.94 and 0.81, 2.00 and 0.60, 2.19 and 0.71 µmol CO2 m−2 s−1, and the litter dry mass remaining was 57.6%, 56.2% and 61.3% in the 20-, 30-, and 46-year-old forests, respectively. We found that the temporal variations of soil respiration and litter decomposition rates can be well explained by soil temperature at 5 cm depth. Both the total soil respiration and litter respiration were significantly positively correlated with the litter decomposition rates. The mean contribution of the litter respiration to the total soil respiration was 31.0%–45.9% for the three different-aged forests. The present study found that the total soil respiration was not significantly affected by forest age when P. masonniana stands exceed a certain age (e.g. >20 years old), but it increased significantly with increased soil temperature. Hence, forest management strategies need to protect the understory vegetation to limit soil warming, in order to reduce the CO2 emission under the currently rapid global warming. The contribution of litter decomposition to the total soil respiration varies across spatial and temporal scales. This indicates the need for separate consideration of soil and litter respiration when assessing the climate impacts on forest carbon cycling. PMID:25004164

  2. Isotopic Forced-Diffusion Technique for Soil Respiration Studies

    NASA Astrophysics Data System (ADS)

    McArthur, G.; Nickerson, N. R.; Egan, J.; Risk, D. A.; Jacobson, G. A.; Cunningham, K. L.; Saad, N.

    2013-12-01

    Isotopic ratio measurements of soil-respired CO2 can provide a wealth of insight into soil-level carbon-cycle processes that is not available using bulk CO2 emission measurements alone. Soil contains substantial amounts of carbon, and can contribute CO2 to the atmosphere through various respiration pathways. Isotopic analysis can distinguish autotrophic root and rhizosphere respiration from heterotrophic respiration due to the catabolism of soil organic matter (SOM). Because of this, researchers have shifted their efforts toward the use of natural abundance and tracer isotopic techniques in ecosystem respiration studies. However, recent experimental and theoretical evidence indicates that these traditional techniques yield biased estimates of the soil isotopic flux, largely owing to disturbances to the soil's natural diffusive regime. To help eliminate these biases, we have developed a new technique called Isotopic Forced-Diffusion (IsoFD). The Isotopic Forced-Diffusion technique integrates a Forced Diffusion dynamic chamber with a cavity ringdown spectrometer measuring d13C-CO2, which are operated together as an integrated system. The system produces real-time, high temporal resolution isotopic soil efflux data. Here, we will present the theory behind this technique, present laboratory data demonstrating the accuracy and precision of the technique in controlled environments and finally field data from two campaigns, showing the ability of the Iso-FD chamber to detect natural diurnal changes in isotopic signature as well as differentiate sources in C3-C4 transitional systems.

  3. Impact of Land Use on Soil Respiration in Southwestern Victoria

    NASA Astrophysics Data System (ADS)

    Teodosio, B.; Daly, E.; Pauwels, V. R. N.

    2015-12-01

    Land use management is one of the key contributors to the global environmental change. Considerable changes in landscapes have been experienced in Southwestern Victoria, Australia in the past two decades. Eucalyptus globulus (blue gum) plantations have expanded, resulting in possible changes in the water and carbon balances of catchments. The shift from pastures to plantations could have a significant impact on the local carbon balance with possible effects on atmospheric CO2 concentration and vegetation productivity. We present preliminary measurements from a field study comparing soil respiration in a plantation and a pasture. Adjacent catchments in Southwestern Victoria, near Gatum, were used as study areas; the prominent difference between the two catchments is the land use, with one catchment being used as a pasture for livestock grazing and the other catchment being mainly planted with blue gums. The variability of soil respiration in the pasture is governed by differences in soil moisture and substrate content due to local features of the topography and livestock grazing. Soil respiration measurements in the plantation were taken on mounds, access tracks, and open spaces. Most observations on mounds had higher soil respiration possibly due to root and mycorrhizal respiration. The measurements in open spaces had comparable values with mound measurements; this might be due to a less limited radiation. The soil respiration between trees had lower values, possibly because of radiation limitation due to the canopy cover. These preliminary measurements allow us to compare soil respiration variability across catchments with different land uses. This is important to estimate CO2 fluxes from soil to the atmosphere in large areas and will be valuable in estimating gross primary production from measurements of net ecosystem exchange.

  4. [Effects of different straw recycling and tillage methods on soil respiration and microbial activity].

    PubMed

    Li, Xiao-sha; Wu, Ning; Liu, Ling; Feng, Yu-peng; Xu, Xu; Han, Hui-fang; Ning, Tang-yuan; Li, Zeng-jia

    2015-06-01

    To explore the effects of different tillage methods and straw recycling on soil respiration and microbial activity in summer maize field during the winter wheat and summer maize double cropping system, substrate induced respiration method and CO2 release method were used to determine soil microbial biomass carbon, microbial activity, soil respiration, and microbial respiratory quotient. The experiment included 3 tillage methods during the winter wheat growing season, i.e., no-tillage, subsoiling and conventional tillage. Each tillage method was companied with 2 straw management patterns, i.e., straw recycling and no straw. The results indicated that the conservation tillage methods and straw recycling mainly affected 0-10 cm soil layer. Straw recycling could significantly improve the microbial biomass carbon and microbial activity, while decrease microbial respiratory quotient. Straw recycling could improve the soil respiration at both seedling stage and anthesis, however, it could reduce the soil respiration at filling stage, wax ripeness, and harvest stage. Under the same straw application, compared with conventional tillage, the soil respiration and microbial respiratory quotient in both subsoiling and no-tillage were reduced, while the microbial biomass carbon and microbial activity were increased. During the summer maize growing season, soil microbial biomass carbon and microbial activity were increased in straw returning with conservation tillage, while the respiratory quotient was reduced. In 0-10 cm soil layer, compared with conventional tillage, straw recycling with subsoiling and no-tillage significantly increased soil microbial biomass carbon by 95.8% and 74.3%, and increased soil microbial activity by 97.1% and 74.2%, respectively.

  5. Relationship between basal soil respiration rate, tree stand and soil characteristics in boreal forests.

    PubMed

    Vanhala, P; Tamminen, P; Fritze, H

    2005-02-01

    Soil respiration is considered to represent the overall microbial activity reflecting mineralisation of organic matter in soil. It is the most commonly used biological variable in soil studies. In long-term monitoring of forested areas, there is a need for reference values for soil microbiological variables in different forest ecosystems. In this study we describe the relationship between soil respiration rate, tree stand and humus chemical characteristics of boreal coniferous forests stands. Soil respiration rate was higher in pine dominated than in spruce dominated study sites when the result was calculated on dry matter bases. However, when calculated on area bases, the result was opposite and no difference was found when the soil respiration rate was calculated on organic carbon bases. Irrespective of the main tree species, the soil respiration rate was equal in different development classes but not equal in soil fertility classes, i.e. within forest site types based on differences in ground vegetation. Respiration rates were clearly higher in mesic sites when calculated on dry matter, C(org) or area bases. However, soil respiration rate did not correlate with soil chemical variables indicating site fertility. Soil respiration rate on dry matter basis was at a lower level in the south and on more fertile sites, and on the other hand at a higher level in older stands and on sites with a thicker organic layer. PMID:15736877

  6. Effects of Picoxystrobin and 4-n-Nonylphenol on Soil Microbial Community Structure and Respiration Activity

    PubMed Central

    Stenrød, Marianne; Klemsdal, Sonja S.; Norli, Hans Ragnar; Eklo, Ole Martin

    2013-01-01

    There is widespread use of chemical amendments to meet the demands for increased productivity in agriculture. Potentially toxic compounds, single or in mixtures, are added to the soil medium on a regular basis, while the ecotoxicological risk assessment procedures mainly follow a chemical by chemical approach. Picoxystrobin is a fungicide that has caused concern due to studies showing potentially detrimental effects to soil fauna (earthworms), while negative effects on soil microbial activities (nitrification, respiration) are shown to be transient. Potential mixture situations with nonylphenol, a chemical frequently occurring as a contaminant in sewage sludge used for land application, infer a need to explore whether these chemicals in mixture could alter the potential effects of picoxystrobin on the soil microflora. The main objective of this study was to assess the effects of picoxystrobin and nonylphenol, as single chemicals and mixtures, on soil microbial community structure and respiration activity in an agricultural sandy loam. Effects of the chemicals were assessed through measurements of soil microbial respiration activity and soil bacterial and fungal community structure fingerprints, together with a degradation study of the chemicals, through a 70 d incubation period. Picoxystrobin caused a decrease in the respiration activity, while 4-n-nonylphenol caused an increase in respiration activity concurring with a rapid degradation of the substance. Community structure fingerprints were also affected, but these results could not be directly interpreted in terms of positive or negative effects, and were indicated to be transient. Treatment with the chemicals in mixture caused less evident changes and indicated antagonistic effects between the chemicals in soil. In conclusion, the results imply that the application of the fungicide picoxystrobin and nonylphenol from sewage sludge application to agricultural soil in environmentally relevant concentrations, as

  7. Sub-10-Micron and Respirable Particles in Lunar Soils

    NASA Astrophysics Data System (ADS)

    Cooper, B. L.; McKay, D. S.; Riofrio, L. M.; Taylor, L. A.; Gonzalez, C. P.

    2010-03-01

    Grain size analyses of Apollo 11 soil 10084 by a laser diffraction technique shows that this soil contains roughly 2% by volume in the respirable (2.5 µm and below) grain size, in agreement with our prior estimates based on extrapolation of sieve data.

  8. [Factors influencing the spatial variability in soil respiration under different land use regimes].

    PubMed

    Chen, Shu-Tao; Liu, Qiao-Hui; Hu, Zheng-Hua; Liu, Yan; Ren, Jing-Quan; Xie, Wei

    2013-03-01

    In order to investigate the factors influencing the spatial variability in soil respiration under different land use regimes, field experiments were performed. Soil respiration and relevant environment, vegetation and soil factors were measured. The spatial variability in soil respiration and the relationship between soil respiration and these measured factors were investigated. Results indicated that land use regimes had significant effects on soil respiration. Soil respiration varied significantly (P < 0.001) among different land use regimes. Soil respiration rates ranged from 1.82 to 7.46 micromol x (m2 x s)(-1), with a difference of 5.62 micromol x (m2 x s)(-1) between the highest and lowest respiration rates. Soil organic carbon was a key factor controlling the spatial variability in soil respiration. In all, ecosystems studied, the relationship between soil respiration and soil organic carbon content can be described by a power function. Soil respiration increased with the increase of soil organic carbon. In forest ecosystem, the relationship between soil respiration and diameter at breast height (DBH) of trees can be explained by a natural logarithmic function. A model composed of soil organic carbon (C, %), available phosphorous (AP, g x kg(-1)) and diameter at breast height (DBH, cm) explained 92.8% spatial variability in soil respiration for forest ecosystems. PMID:23745410

  9. [Variation characteristic in soil respiration of apple orchard and its biotic and abiotic influencing factors].

    PubMed

    Wang, Rui; Guo, Sheng-Li; Liu, Qing-Fang; Zhang, Yan-Jun; Jiang, Ji-Shao; Guo, Hui-Min; Li, Ru-Jian

    2014-05-01

    To evaluate the orchard variability of soil respiration and the response of soil respiration to its influencing factors is helpful for a deep understanding about the effects of converting cropland to apple orchard. A field experiment was conducted in the Changwu State Key Agro-Ecological Station. Soil respiration, soil temperature, soil moisture and roots biomasses were periodically measured in a mature apple orchard during 2011 and 2012. Soil respiration decreased as the distance from the trunk increased. The cumulative soil respiration in the 0.5 m-distance from the trunk was 20% and 31% higher than that in the 2 m-distance from the trunk, respectively in 2011 and 2012. The temperature sensitivity of soil respiration (Q10) was relatively lower in the 2 m-distance than that in the 0. 5 m-distance in both years. Soil temperature and soil moisture were slightly higher in the 2 m-distance, but there was no significant difference between the 2 m-distance and the 0. 5 m-distance. Soil respiration and soil temperature showed a significant exponential relationship, but there was no positive correlation between soil moisture and soil respiration. Soil temperature changes can explain seasonal variation of soil respiration well, but it could not explain its spatial variability. Root density was an important factor for the spatial variability of soil respiration and Q15. Variation of soil respiration coefficient was 23% -31%. Therefore, the distance from the trunk should be considered when estimating orchards soil respiration.

  10. Responses of soil respiration to elevated CO2, air warming, and changing soil water availability in an old-field grassland

    SciTech Connect

    Wan, Shiqiang; Norby, Richard J; Childs, Joanne; Weltzin, Jake

    2007-01-01

    Responses of soil respiration to atmospheric and climatic change will have profound impacts on ecosystem and global C cycling in the future. This study was conducted to examine effects on soil respiration of the concurrent driving factors of elevated atmospheric CO2 concentration, rising temperature, and changing precipitation in a constructed old-field grassland in eastern Tennessee, USA. Model ecosystems of seven old-field species in 12 open-top chambers (4 m in diameter) were treated with two CO2 (ambient and ambient plus 300 ppm) and two temperature (ambient and ambient plus 3 C) levels. Two split plots with each chamber were assigned with high and low soil moisture levels. During the 19-month experimental period from June 2003 to December 2004, higher CO2 concentration and soil water availability significantly increased mean soil respiration by 35.8% and 15.7%, respectively. The effects of air warming on soil respiration varied seasonally from small reductions to significant increases to no response, and there was no significant main effect. In the wet side of elevated CO2 chambers, air warming consistently caused increases in soil respiration, whereas in other three combinations of CO2 and water treatments, warming tended to decrease soil respiration over the growing season but increase it over the winter. There were no interactive effects on soil respiration among any two or three treatment factors irrespective of testing time period. Temperature sensitivity of soil respiration was reduced by air warming, lower in the wet than the dry side, and not affected by CO2 treatment. Variations of soil respiration responses with soil temperature and soil moisture ranges could be primarily attributable to the seasonal dynamics of plant growth and its responses to the three treatments. Using a conceptual model to interpret the significant relationships of treatment-induced changes in soil respiration with changes in soil temperature and moisture observed in this study

  11. Response of soil respiration to acid rain in forests of different maturity in southern China.

    PubMed

    Liang, Guohua; Liu, Xingzhao; Chen, Xiaomei; Qiu, Qingyan; Zhang, Deqiang; Chu, Guowei; Liu, Juxiu; Liu, Shizhong; Zhou, Guoyi

    2013-01-01

    The response of soil respiration to acid rain in forests, especially in forests of different maturity, is poorly understood in southern China despite the fact that acid rain has become a serious environmental threat in this region in recent years. Here, we investigated this issue in three subtropical forests of different maturity [i.e. a young pine forest (PF), a transitional mixed conifer and broadleaf forest (MF) and an old-growth broadleaved forest (BF)] in southern China. Soil respiration was measured over two years under four simulated acid rain (SAR) treatments (CK, the local lake water, pH 4.5; T1, water pH 4.0; T2, water pH 3.5; and T3, water pH 3.0). Results indicated that SAR did not significantly affect soil respiration in the PF, whereas it significantly reduced soil respiration in the MF and the BF. The depressed effects on both forests occurred mostly in the warm-wet seasons and were correlated with a decrease in soil microbial activity and in fine root biomass caused by soil acidification under SAR. The sensitivity of the response of soil respiration to SAR showed an increasing trend with the progressive maturity of the three forests, which may result from their differences in acid buffering ability in soil and in litter layer. These results indicated that the depressed effect of acid rain on soil respiration in southern China may be more pronounced in the future in light of the projected change in forest maturity. However, due to the nature of this field study with chronosequence design and the related pseudoreplication for forest types, this inference should be read with caution. Further studies are needed to draw rigorous conclusions regarding the response differences among forests of different maturity using replicated forest types.

  12. Response of soil respiration to acid rain in forests of different maturity in southern China.

    PubMed

    Liang, Guohua; Liu, Xingzhao; Chen, Xiaomei; Qiu, Qingyan; Zhang, Deqiang; Chu, Guowei; Liu, Juxiu; Liu, Shizhong; Zhou, Guoyi

    2013-01-01

    The response of soil respiration to acid rain in forests, especially in forests of different maturity, is poorly understood in southern China despite the fact that acid rain has become a serious environmental threat in this region in recent years. Here, we investigated this issue in three subtropical forests of different maturity [i.e. a young pine forest (PF), a transitional mixed conifer and broadleaf forest (MF) and an old-growth broadleaved forest (BF)] in southern China. Soil respiration was measured over two years under four simulated acid rain (SAR) treatments (CK, the local lake water, pH 4.5; T1, water pH 4.0; T2, water pH 3.5; and T3, water pH 3.0). Results indicated that SAR did not significantly affect soil respiration in the PF, whereas it significantly reduced soil respiration in the MF and the BF. The depressed effects on both forests occurred mostly in the warm-wet seasons and were correlated with a decrease in soil microbial activity and in fine root biomass caused by soil acidification under SAR. The sensitivity of the response of soil respiration to SAR showed an increasing trend with the progressive maturity of the three forests, which may result from their differences in acid buffering ability in soil and in litter layer. These results indicated that the depressed effect of acid rain on soil respiration in southern China may be more pronounced in the future in light of the projected change in forest maturity. However, due to the nature of this field study with chronosequence design and the related pseudoreplication for forest types, this inference should be read with caution. Further studies are needed to draw rigorous conclusions regarding the response differences among forests of different maturity using replicated forest types. PMID:23626790

  13. Using Headspace Equilibration to Measure the d13C of Soil-Respired CO2

    NASA Astrophysics Data System (ADS)

    Robertson, M. A.; Powers, E.; Marshall, J.

    2007-12-01

    Soil respiration is an important component of the global carbon cycle and can account for as much as 70% of ecosystem respiration. Soil gas flux measurements have been combined with stable isotope analysis to examine ecosystem properties and processes such as water-use efficiency and the role of above ground weather in controlling soil respiration. However, current methods of measuring the δ13C of soil-respired CO2 are either inherently inaccurate or time-consuming and tedious. An alternative method of obtaining this value offers a potential solution to these problems. In this method, plastic chambers are fitted with rubber septa to allow for sample collection, then inverted and partially buried in soil. The chamber headspace is allowed to come to equilibrium with soil air. In this study we tested the viability of this method by examining whether frequent resampling of respiration chambers affected δ13C measurements, whether headspace CO2 concentration and δ13C values approached equilibrium asymptotically, and whether simulated and actual diel temperature cycles affected estimates of δ13C. All experiments were conducted on respiration chambers inverted in potting soil and placed in a Conviron growth chamber, with the exception of one field test that was conducted on respiration chambers installed in a Northern Idaho experimental forest. Samples were collected with a syringe and stored in glass vials for analysis by a ratioing mass spectrometer. We found that resampling respiration chambers as frequently as every 10 minutes had no significant effect on final δ13C values, that both chamber CO2 concentrations and δ13C values exhibited an asymptotic approach to equilibrium, and that the equilibrium value was offset from the initial flux by the amount we expected, approximately 4 ‰. However, we also found that diel temperature variation affected both headspace CO2 concentration and δ13C in the lab and in the field. We concluded that if this method is used in

  14. Sensing winter soil respiration dynamics in near-real time

    NASA Astrophysics Data System (ADS)

    Contosta, A.; Burakowski, E. A.; Varner, R. K.; Frey, S. D.

    2014-12-01

    Some of the largest reductions in seasonal snow cover are projected to occur in temperate latitudes. Limited measurements from these ecosystems indicate that winter soil respiration releases as much as 30% of carbon fixed during the previous growing season. This respiration is possible with a snowpack that insulates soil from ambient fluctuations in climate. However, relationships among snowpack, soil temperature, soil moisture, and winter soil respiration in temperate regions are not well-understood. Most studies have infrequently sampled soil respiration and its drivers, and most measurements have been limited to the soil surface. We made near-real time, continuous measurements of temperature, moisture, and CO2 fluxes from the soil profile, through the snowpack, and into the atmosphere in a deciduous forest of New Hampshire, USA. We coupled these data with daily sampling of snow depth and snow water equivalent (SWE). Our objectives were to continuously measure soil CO2 production (Psoil) and CO2 flux through the snowpack (Fsnow) and to compare Fsnow and Psoil with environmental drivers. We found that Fsnow was more dynamic than Psoil, changing as much as 30% over several days with shifting environmental conditions. Multiple regression indicated that SWE, air temperature, surface soil temperature, surface soil CO2 concentrations, and soil moisture at 15 cm were significant predictors of Fsnow. The transition of surface temperature from below to above 0°C was particularly important as it represented a phase change from ice to liquid water. Only air temperature and soil moisture at 15 cm were significant drivers of Psoil, where higher moisture at 15 cm resulted in lower Psoil rates. Time series analysis showed that Fsnow lagged 40 days behind Psoil. This lag may be due to slow CO2 diffusion through soil to overlying snow under high moisture conditions. Our results suggest that surface soil CO2 losses are driven by rapid changes in snow cover, surface temperature

  15. Quantification of soil respiration in forest ecosystems across China

    NASA Astrophysics Data System (ADS)

    Song, Xinzhang; Peng, Changhui; Zhao, Zhengyong; Zhang, Zhiting; Guo, Baohua; Wang, Weifeng; Jiang, Hong; Zhu, Qiuan

    2014-09-01

    We collected 139 estimates of the annual forest soil CO2 flux and 173 estimates of the Q10 value (the temperature sensitivity) assembled from 90 published studies across Chinese forest ecosystems. We analyzed the annual soil respiration (Rs) rates and the temperature sensitivities of seven forest ecosystems, including evergreen broadleaf forests (EBF), deciduous broadleaf forests (DBF), broadleaf and needleleaf mixed forests (BNMF), evergreen needleleaf forests (ENF), deciduous needleleaf forests (DNF), bamboo forests (BF) and shrubs (SF). The results showed that the mean annual Rs rate was 33.65 t CO2 ha-1 year-1 across Chinese forest ecosystems. Rs rates were significantly different (P < 0.001) among the seven forest types, and were significantly and positively influenced by mean annual temperature (MAT), mean annual precipitation (MAP), and actual evapotranspiration (AET); but negatively affected by latitude and elevation. The mean Q10 value of 1.28 was lower than the world average (1.4-2.0). The Q10 values derived from the soil temperature at a depth of 5 cm varied among forest ecosystems by an average of 2.46 and significantly decreased with the MAT but increased with elevation and latitude. Moreover, our results suggested that an artificial neural network (ANN) model can effectively predict Rs across Chinese forest ecosystems. This study contributes to better understanding of Rs across Chinese forest ecosystems and their possible responses to global warming.

  16. Plutonium hazard in respirable dust on the surface of soil.

    PubMed

    Johnson, C J; Tidball, R R; Severson, R C

    1976-08-01

    Plutonium-239 in the fine particulate soil fraction of surface dust is subject to suspension by air currents and is a potential health hazard to humans who may inhale it. This respirable particulate fraction is defined as particles less than or equal to 5 micrometers. The respirable fraction of surface dust was separated by ultrasonic dispersion and a standard water-sedimentation procedure. Plutonium concentration in this fraction of off-site soils located downwind from the Rocky Flats Nuclear Weapons Plant (Jefferson County, Colorado) were as much as 380 times the background concentration. It is prposed that this method of evaluation defines more precisely the potential health hazard from the respirable fraction of plutonium-contaminated soils. PMID:941018

  17. Impact of some selected insecticides application on soil microbial respiration.

    PubMed

    Latif, M A; Razzaque, M A; Rahman, M M

    2008-08-15

    The aim of present study was to investigate the impact of selected insecticides used for controlling brinjal shoot and fruit borer on soil microorganisms and to find out the insecticides or nontoxic to soil microorganism the impact of nine selected insecticides on soil microbial respiration was studied in the laboratory. After injection of different insecticides solutions, the soil was incubated in the laboratory at room temperature for 32 days. The amount of CO2 evolved due to soil microbial respiration was determined at 2, 4, 8, 16, 24 and 32 days of incubation. Flubendiamide, nimbicidine, lambda-cyhalothrin, abamectin and thiodicarb had stimulatory effect on microbial respiration during the initial period of incubation. Chlorpyriphos, cartap and carbosulfan had inhibitory effect on microbial respiration and cypermethrin had no remarkable effect during the early stage of incubation. The negative effect of chlorpyriphos, cartap and carbosulfan was temporary, which was disappeared after 4 days of insecticides application. No effect of the selected insecticides on soil microorganisms was observed after 24 or 32 days of incubation. PMID:19266909

  18. Microbial respiration per unit microbial biomass increases with carbon-to-nutrient ratios in soils

    NASA Astrophysics Data System (ADS)

    Spohn, Marie; Chodak, Marcin

    2015-04-01

    The ratio of carbon-to-nutrient in forest floors is usually much higher than the ratio of carbon-to-nutrient that soil microorganisms require for their nutrition. In order to understand how this mismatch affects carbon cycling, the respiration rate per unit soil microbial biomass carbon - the metabolic quotient (qCO2) - was studied. This was done in a field study (Spohn and Chodak, 2015) and in a meta-analysis of published data (Spohn, 2014). Cores of beech, spruce, and mixed spruce-beech forest soils were cut into slices of 1 cm from the top of the litter layer down to 5 cm in the mineral soil, and the relationship between the qCO2 and the soil carbon-to-nitrogen (C:N) and the soil carbon-to-phosphorus (C:P) ratio was analyzed. We found that the qCO2 was positively correlated with soil C:N ratio in spruce soils (R = 0.72), and with the soil C:P ratio in beech (R = 0.93), spruce (R = 0.80) and mixed forest soils (R = 0.96). We also observed a close correlation between the qCO2 and the soil C concentration in all three forest types. Yet, the qCO2 decreased less with depth than the C concentration in all three forest types, suggesting that the change in qCO2 is not only controlled by the soil C concentration. We conclude that microorganisms increase their respiration rate per unit biomass with increasing soil C:P ratio and C concentration, which adjusts the substrate to their nutritional demands in terms of stoichiometry. In an analysis of literature data, I tested the effect of the C:N ratio of soil litter layers on microbial respiration in absolute terms and per unit microbial biomass C. For this purpose, a global dataset on the microbial respiration rate per unit microbial biomass C - termed the metabolic quotient (qCO2) - was compiled form literature data. It was found that the qCO2 in the soil litter layers was positively correlated with the litter C:N ratio and negatively related with the litter nitrogen (N) concentration. The positive relation between the qCO2

  19. Short term effects of fire on soil respiration in Peruvian Amazon

    NASA Astrophysics Data System (ADS)

    Suarez, L. F.; Kruijt, B.

    2008-05-01

    Severe changes are affecting the role of Amazon in the Earth system. One of these possible effects could be the modification of the role of soils in the carbon cycle due to land use and land cover change activities mainly involving the change of forest by crops. In this sense, fire is the main tool used by farmers for land use and also is an important factor for mobilizing C from the soil to the atmosphere, mainly as CO2. This could have an important effect in the global warming. This proposal will evaluate the variation of the soil respiration related to the seasonality and the fire effects on soils in the Amazon of Peru and Brazil. In experimental locations of Peru with different vegetation cover (forest and pasture), we measured soil respiration along with the organic carbon and the microbial biomass of soils during campaigns covering wet and dry seasons. Complementary measurements of soil temperature, water and nutrient content were performed. Also, we reproduced a fire experiment simulating agricultural local activity by the technique of "slash and burn" to evaluate fire effects on soil respiration. Measurements were taken after the soil cooled and at least 3 days after the fire. Additionally, the carbon stocks of the subplots were evaluated. Evaluation of the variations of CO2 fluxes and the capacity of adaptation to fire and water content are discussed through the comparisons of the different locations, type of soils and concentration of available N (nitrate and ammonium) as an indicator of nutrient content.

  20. Invariant Temperature Sensitivity of Soil Respiration with Depth

    NASA Astrophysics Data System (ADS)

    Hicks Pries, C.; Torn, M. S.; Castanha, C.; Porras, R. C.

    2015-12-01

    Over half of global soil organic carbon (SOC) is stored in subsurface soils (>30 cm), but little is known about the vulnerability of this deep SOC to climate change. Most soil warming experiments have only warmed surface soils, so the temperature sensitivity of deeper SOC and its potential to generate a positive feedback to climate change is undetermined. We are currently investigating how SOC down to 1 m deep responds to experimental in situ soil warming (+4°C). Our field site is a coniferous forest in the foothills of the Sierra Nevada in California, USA, whose soils are sandy, mixed, mesic Ultic Haploxeralfs. Our objectives are to understand (1) how the mechanisms controlling SOC turnover differ with depth and (2) how the temperature sensitivity of soil respiration differs by depth. Warming began in October 2013, and we have successfully warmed 1 m of the soil profile to 4°C (±0.5) above ambient temperatures at each depth and maintained this warming throughout different seasons. We have taken monthly surface CO2 flux measurements and monthly gas samples from stainless steel tubes at 15, 30, 50, 70, and 90 cm depths. We have collected soil water from tension lysimeters at 30 and 70 cm after large rain events. Warming has increased CO2 production at all depths of the warmed plots. Warming has also significantly increased soil respiration from the surface by 39% relative to the control and increased concentrations of dissolved organic carbon in soil water at both depths. The apparent Q10 of surface soil respiration and CO2 production at all depths is greater than 2, indicating that decomposition is similarly temperature sensitive at all depths. This study is one of the first to test whole-profile SOC responses to warming and shows that deep soil carbon is equally vulnerable to climate change in these upland mineral soils.

  1. Effect of biochar produced at different pyrolysis temperature on the soil respiration of abandoned mine soil

    NASA Astrophysics Data System (ADS)

    Kim, Yong Seong; Kim, Juhee; Hwang, Wonjae; Hyun, Seunghun

    2015-04-01

    infrared gas sensor, and these data were sent to a data logger. During the measuring periods, the cumulative CO2 emission were similar between the control (516.8 mg-CO2 kg-1-soil) and BC4 5% mixture (519.3 mg-CO2 kg-1-soil), while BC7 5% mixture was significantly decreased (356.1 mg-CO2 kg-1-soil) compared to other treatment and control. Because the degradation rate of biochar generally increased with decreasing pyrolysis temperature, this result suggest that the soil respiration rates of biochar amended soils are affected by physico-chemical properties of biochar during early incubation periods (about 1 weeks), For example, surface properties of used biochars, which are related to adsorption of soil organic matter and CO2, have different properties with pyrolysis temperature such as specific surface area (BC4=5.08 m2g-1; BC7=260.75 m2 g-1, respectively), average pore diameter (BC4=4,673 nm; BC7=2,606 nm, respectively), and functional groups of biochar surface. However, there was not clear evidence of biochar-mine soil interaction process, because of the short observation periods. Future work should focus on the adsorption of CO2 and soil organic matter of biochar and soil-biochar interaction with long time periods and various biological test.

  2. Updating soil CO2 emission experiments to assess climate change effects and extracellular soil respiration

    NASA Astrophysics Data System (ADS)

    Vidal Vazquez, Eva; Paz Ferreiro, Jorge

    2014-05-01

    Experimental work is an essential component in training future soil scientists. Soil CO2 emission is a key issue because of the potential impacts of this process on the greenhouse effect. The amount of organic carbon stored in soils worldwide is about 1600 gigatons (Gt) compared to 750 Gt in the atmosphere mostly in the form of CO2. Thus, if soil respiration increased slightly so that just 10% of the soil carbon pool was converted to CO2, atmospheric CO2 concentrations in the atmosphere could increase by one-fifth. General circulation model predictions indicate atmosphere warming between 2 and 5°C (IPCC 2007) and precipitation changes ranging from about -15 to +30%. Traditionally, release of CO2 was thought to occur only in an intracellular environment; however, recently CO2 emissions have been in irradiated soil, in the absence of microorganisms (Maire et al., 2013). Moreover, soil plays a role in the stabilization of respiration enzymes promoting CO2 release after microorganism death. Here, we propose to improve CO2 emission experiments commonly used in soil biology to investigate: 1) effects of climatic factors on soil CO2 emissions, and 2) rates of extracellular respiration in soils and how these rates are affected by environmental factors. Experiment designed to assess the effect of climate change can be conducted either in field conditions under different ecosystems (forest, grassland, cropland) or in a greenhouse using simple soil chambers. The interactions of climate change in CO2 emissions are investigated using climate-manipulation experiment that can be adapted to field or greenhouse conditions (e.g. Mc Daniel et al., 2013). The experimental design includes a control plot (without soil temperature and rain manipulation) a warming treatment as well as wetting and/or drying treatments. Plots are warmed to the target temperature by procedures such as infrared heaters (field) or radiant cable (greenhouse). To analyze extracellular respiration, rates of CO2

  3. Soil respiration, CH4, and N2O fluxes in a semi-arid grassland affected by elevated CO2, warming, and water availability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As the global climate changes, information on how those changes will affect the land-atmosphere exchange of greenhouse gases is needed to understand and predict future exchanges. While considerable research has been done on the effects of single climate factors, almost no work has been done evaluati...

  4. Forest thinning and soil respiration in a ponderosa pine plantation in the Sierra Nevada.

    PubMed

    Tang, Jianwu; Qi, Ye; Xu, Ming; Misson, Laurent; Goldstein, Allen H

    2005-01-01

    Soil respiration is controlled by soil temperature, soil water, fine roots, microbial activity, and soil physical and chemical properties. Forest thinning changes soil temperature, soil water content, and root density and activity, and thus changes soil respiration. We measured soil respiration monthly and soil temperature and volumetric soil water continuously in a young ponderosa pine (Pinus ponderosa Dougl. ex P. Laws. & C. Laws.) plantation in the Sierra Nevada Mountains in California from June 1998 to May 2000 (before a thinning that removed 30% of the biomass), and from May to December 2001 (after thinning). Thinning increased the spatial homogeneity of soil temperature and respiration. We conducted a multivariate analysis with two independent variables of soil temperature and water and a categorical variable representing the thinning event to simulate soil respiration and assess the effect of thinning. Thinning did not change the sensitivity of soil respiration to temperature or to water, but decreased total soil respiration by 13% at a given temperature and water content. This decrease in soil respiration was likely associated with the decrease in root density after thinning. With a model driven by continuous soil temperature and water time series, we estimated that total soil respiration was 948, 949 and 831 g C m(-2) year(-1) in the years 1999, 2000 and 2001, respectively. Although thinning reduced soil respiration at a given temperature and water content, because of natural climate variability and the thinning effect on soil temperature and water, actual cumulative soil respiration showed no clear trend following thinning. We conclude that the effect of forest thinning on soil respiration is the combined result of a decrease in root respiration, an increase in soil organic matter, and changes in soil temperature and water due to both thinning and interannual climate variability.

  5. Soil Respiration of Three Mangrove Forests on Sanibel Island, Florida

    NASA Astrophysics Data System (ADS)

    Cartwright, F.; Bovard, B. D.

    2011-12-01

    Carbon cycling studies conducted in mangrove forests have typically focused on aboveground processes. Our understanding of carbon storage in these systems is therefore limited by the lack information on belowground processes such as fine root production and soil respiration. To our knowledge there exist no studies investigating temporal patterns in and environmental controls on soil respiration in multiple types of mangrove ecosystems concurrently. This study is part of a larger study on carbon storage in three mangrove forests on Sanibel Island, Florida. Here we report on eight months of soil respiration data within these forests that will ultimately be incorporated into an annual carbon budget for each habitat type. Soil respiration was monitored in the following three mangrove habitat types: a fringe mangrove forest dominated by Rhizophora mangle, a basin mangrove forest dominated by Avicennia germinans, and a higher elevation forest comprised of a mix of Avicennia germinans and Laguncularia racemosa, and non-woody salt marsh species. Beginning in June of 2010, we measured soil emissions of carbon dioxide at 5 random locations within three-100 m2 plots within each habitat type. Sampling was performed at monthly intervals and conducted over the course of three days. For each day, one plot from each habitat type was measured. In addition to soil respiration, soil temperature, salinity and gravimetric moisture content were also measured. Our data indicate the Black mangrove forest, dominated by Avicennia germinans, experiences the highest rates of soil respiration with a mean rate of 4.61 ± 0.60 μmol CO2 m-2 s-1. The mixed mangrove and salt marsh habitat has the lowest soil carbon emission rates with a mean of 2.78 ± 0.40 μmol CO2 m-2 s-1. Soil carbon effluxes appear to peak in the early part of the wet season around May to June and are lower and relatively constant the remainder of the year. Our data also suggest there are important but brief periods where

  6. Effects of Manipulated Above- and Belowground Organic Matter Input on Soil Respiration in a Chinese Pine Plantation

    PubMed Central

    Zhao, Bo; Wu, Lianhai; Zhang, Chunyu; Zhao, Xiuhai; Gadow, Klaus v.

    2015-01-01

    Alteration in the amount of soil organic matter input can have profound effect on carbon dynamics in forest soils. The objective of our research was to determine the response in soil respiration to above- and belowground organic matter manipulation in a Chinese pine (Pinus tabulaeformis) plantation. Five organic matter treatments were applied during a 2-year experiment: both litter removal and root trenching (LRRT), only litter removal (LR), control (CK), only root trenching (RT) and litter addition (LA). We found that either aboveground litter removal or root trenching decreased soil respiration. On average, soil respiration rate was significantly decreased in the LRRT treatment, by about 38.93% ± 2.01% compared to the control. Soil respiration rate in the LR treatment was 30.65% ± 1.87% and in the RT treatment 17.65% ± 1.95% lower than in the control. Litter addition significantly increased soil respiration rate by about 25.82% ± 2.44% compared to the control. Soil temperature and soil moisture were the main factors affecting seasonal variation in soil respiration. Up to the 59.7% to 82.9% seasonal variation in soil respiration is explained by integrating soil temperature and soil moisture within each of the various organic matter treatments. The temperature sensitivity parameter, Q10, was higher in the RT (2.72) and LA (3.19) treatments relative to the control (2.51), but lower in the LRRT (1.52) and LR treatments (1.36). Our data suggest that manipulation of soil organic matter input can not only alter soil CO2 efflux, but also have profound effect on the temperature sensitivity of organic carbon decomposition in a temperate pine forest. PMID:25970791

  7. Effects of manipulated above- and belowground organic matter input on soil respiration in a Chinese pine plantation.

    PubMed

    Fan, Juan; Wang, Jinsong; Zhao, Bo; Wu, Lianhai; Zhang, Chunyu; Zhao, Xiuhai; Gadow, Klaus V

    2015-01-01

    Alteration in the amount of soil organic matter input can have profound effect on carbon dynamics in forest soils. The objective of our research was to determine the response in soil respiration to above- and belowground organic matter manipulation in a Chinese pine (Pinus tabulaeformis) plantation. Five organic matter treatments were applied during a 2-year experiment: both litter removal and root trenching (LRRT), only litter removal (LR), control (CK), only root trenching (RT) and litter addition (LA). We found that either aboveground litter removal or root trenching decreased soil respiration. On average, soil respiration rate was significantly decreased in the LRRT treatment, by about 38.93% ± 2.01% compared to the control. Soil respiration rate in the LR treatment was 30.65% ± 1.87% and in the RT treatment 17.65% ± 1.95% lower than in the control. Litter addition significantly increased soil respiration rate by about 25.82% ± 2.44% compared to the control. Soil temperature and soil moisture were the main factors affecting seasonal variation in soil respiration. Up to the 59.7% to 82.9% seasonal variation in soil respiration is explained by integrating soil temperature and soil moisture within each of the various organic matter treatments. The temperature sensitivity parameter, Q10, was higher in the RT (2.72) and LA (3.19) treatments relative to the control (2.51), but lower in the LRRT (1.52) and LR treatments (1.36). Our data suggest that manipulation of soil organic matter input can not only alter soil CO2 efflux, but also have profound effect on the temperature sensitivity of organic carbon decomposition in a temperate pine forest.

  8. Does the embryonic axis affect respiration in pea cotyledons?

    PubMed

    Parys, E; Romanowska, E; Poskuta, J

    1984-05-01

    The conditions of imbibition crucially affected respiration of the excised pea cotyledons, Pisum sativum L. var. Bördi, during subsequent incubation. When excised cotyledons were immersed in water during imbibition, their respiration rate was lower than that of attached cotyledons up to 96 h of incubation. Hydration of excised cotyledons was faster than that of attached cotyledons, particularly at early stages of imbibition. The dry weight of excised cotyledons, however, decreased more rapidly than that of attached cotyledons. When excised cotyledons were kept on moist filter paper from the onset of imbibition, their respiration rate was the same as that of attached cotyledons during later incubation. In addition, the hydration rate of both excised and attached cotyledons was the same under such conditions, whereas the dry weight of the attached cotyledons decreased more rapidly than those of excised cotyledons. It was concluded that the respiration rate of the excised cotyledons during incubation was only dependent on the conditions used during imbibition. Hence, the embryonic axis had not effect on the development and maintenance of the respiratory activity in the cotyledons of germinating peas.

  9. Gap filling strategies and error in estimating annual soil respiration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil respiration (Rsoil) is one of the largest CO2 fluxes in the global carbon (C) cycle. Estimation of annual Rsoil requires extrapolation of survey measurements or gap-filling of automated records to produce a complete time series. While many gap-filling methodologies have been employed, there is ...

  10. Changes in soil respiration after thinning activities in dense Aleppo pine forests

    NASA Astrophysics Data System (ADS)

    Llovet, Joan; Alonso, Macià; Cerdà, Artemi

    2015-04-01

    Forest fires are a widespread perturbation in Mediterranean areas, and they have tended to increase during the last decades (Pausas, 2004; Moreno et al, 1998). Aleppo pine (Pinus halepensis Mill) is dominant specie in some forest landscapes of western Mediterranean Basin, due to its capacity to colonize abandoned fields, and also due to afforestation practices mainly performed during the 20th century (Ruiz Navarro et al., 2009). Aleppo pine tends to die as consequence of forest fires, although it is able to disperse a high quantity of seeds which easily germinates. These dispersion and germination can result in dense forests with high inter and intra-specific competition, low diversity, low growth, and high fuel accumulation, increasing the risk of new forest fires. These forests of high density present ecological problems and management difficulties that require preventive treatments. Thinning treatments are common in these types of communities, but the management has to be oriented towards strengthening their functions. In the context of global change, better understandings of the implications of forest management practices in the carbon cycle are necessary. The objective of this study was to examine the evolution of seasonal soil respiration after treatment of selective thinning in dense Aleppo pine forests. The study area covers three localities placed in the Valencian Community (E Spain) affected by a forest fire in 1994. Thinning activities were done 16 years after the fire, reducing pine density from around 100,000 individuals per hectare to around 900 individuals per hectare. Soil respiration was measured in situ with a portable soil respiration instrument (LI-6400, LiCor, Lincoln, NB, USA) fitted with a soil respiration chamber (6400-09, LiCor, Lincoln, NB, USA). We installed 12 plots per treatment (control and thinned) and locality, being a total of 72 plots. We carried out 13 measurements covering a period of one year. We also estimated other related

  11. Soil moisture sensitivity of autotrophic and heterotrophic forest floor respiration in boreal xeric pine and mesic spruce forests

    NASA Astrophysics Data System (ADS)

    Ťupek, Boris; Launiainen, Samuli; Peltoniemi, Mikko; Heikkinen, Jukka; Lehtonen, Aleksi

    2016-04-01

    Litter decomposition rates of the most process based soil carbon models affected by environmental conditions are linked with soil heterotrophic CO2 emissions and serve for estimating soil carbon sequestration; thus due to the mass balance equation the variation in measured litter inputs and measured heterotrophic soil CO2 effluxes should indicate soil carbon stock changes, needed by soil carbon management for mitigation of anthropogenic CO2 emissions, if sensitivity functions of the applied model suit to the environmental conditions e.g. soil temperature and moisture. We evaluated the response forms of autotrophic and heterotrophic forest floor respiration to soil temperature and moisture in four boreal forest sites of the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) by a soil trenching experiment during year 2015 in southern Finland. As expected both autotrophic and heterotrophic forest floor respiration components were primarily controlled by soil temperature and exponential regression models generally explained more than 90% of the variance. Soil moisture regression models on average explained less than 10% of the variance and the response forms varied between Gaussian for the autotrophic forest floor respiration component and linear for the heterotrophic forest floor respiration component. Although the percentage of explained variance of soil heterotrophic respiration by the soil moisture was small, the observed reduction of CO2 emissions with higher moisture levels suggested that soil moisture response of soil carbon models not accounting for the reduction due to excessive moisture should be re-evaluated in order to estimate right levels of soil carbon stock changes. Our further study will include evaluation of process based soil carbon models by the annual heterotrophic respiration and soil carbon stocks.

  12. 2 D patterns of soil gas diffusivity , soil respiration, and methane oxidation in a soil profile

    NASA Astrophysics Data System (ADS)

    Maier, Martin; Schack-Kirchner, Helmer; Lang, Friederike

    2015-04-01

    The apparent gas diffusion coefficient in soil (DS) is an important parameter describing soil aeration, which makes it a key parameter for root growth and gas production and consumption. Horizontal homogeneity in soil profiles is assumed in most studies for soil properties - including DS. This assumption, however, is not valid, even in apparently homogeneous soils, as we know from studies using destructive sampling methods. Using destructive methods may allow catching a glimpse, but a large uncertainty remains, since locations between the sampling positions cannot be analyzed, and measurements cannot be repeated. We developed a new method to determine in situ the apparent soil gas diffusion coefficient in order to examine 2 D pattern of DS and methane oxidation in a soil profile. Different tracer gases (SF6, CF4, C2H6) were injected continuously into the subsoil and measured at several locations in the soil profile. These data allow for modelling inversely the 2 D patterns of DS using Finite Element Modeling. The 2D DS patterns were then combined with naturally occurring CH4 and CO2 concentrations sampled at the same locations to derive the 2D pattern of soil respiration and methane oxidation in the soil profile. We show that methane oxidation and soil respiration zones shift within the soil profile while the gas fluxes at the surface remain rather stable during a the 3 week campaign.

  13. Simple Laboratory Experiment for Illustrating Soil Respiration.

    ERIC Educational Resources Information Center

    Hattey, J. A.; Johnson, G. V.

    1997-01-01

    Describes an experiment to illustrate the effect of food source and added nutrients (N) on microbial activity in the soil. Supplies include air-dried soil, dried plant material, sources of carbon and nitrogen, a trap such as KOH, colored water, and a 500-mL Erlenmeyer flask. Includes a diagram of an incubation chamber to demonstrate microbial…

  14. [Soil Microbial Respiration Under Different Soil Temperature Conditions and Its Relationship to Soil Dissolved Organic Carbon and Invertase].

    PubMed

    Wu, Jing; Chen, Shu-tao; Hu, Zheng-hua; Zhang, Xu

    2015-04-01

    In order to investigate the soil microbial respiration under different temperature conditions and its relationship to soil dissolved organic carbon ( DOC) and invertase, an indoor incubation experiment was performed. The soil samples used for the experiment were taken from Laoshan, Zijinshan, and Baohuashan. The responses of soil microbial respiration to the increasing temperature were studied. The soil DOC content and invertase activity were also measured at the end of incubation. Results showed that relationships between cumulative microbial respiration of different soils and soil temperature could be explained by exponential functions, which had P values lower than 0.001. The coefficient of temperature sensitivity (Q10 value) varied from 1.762 to 1.895. The Q10 value of cumulative microbial respiration decreased with the increase of soil temperature for all soils. The Q10 value of microbial respiration on 27 days after incubation was close to that of 1 day after incubation, indicating that the temperature sensitivity of recalcitrant organic carbon may be similar to that of labile organic carbon. For all soils, a highly significant ( P = 0.003 ) linear relationship between cumulative soil microbial respiration and soil DOC content could be observed. Soil DOC content could explain 31.6% variances of cumulative soil microbial respiration. For the individual soil and all soils, the relationship between cumulative soil microbial respiration and invertase activity could be explained by a highly significant (P < 0.01) linear regression function, which suggested that invertase was a good indicator of the magnitude of soil microbial respiration.

  15. [Soil Microbial Respiration Under Different Soil Temperature Conditions and Its Relationship to Soil Dissolved Organic Carbon and Invertase].

    PubMed

    Wu, Jing; Chen, Shu-tao; Hu, Zheng-hua; Zhang, Xu

    2015-04-01

    In order to investigate the soil microbial respiration under different temperature conditions and its relationship to soil dissolved organic carbon ( DOC) and invertase, an indoor incubation experiment was performed. The soil samples used for the experiment were taken from Laoshan, Zijinshan, and Baohuashan. The responses of soil microbial respiration to the increasing temperature were studied. The soil DOC content and invertase activity were also measured at the end of incubation. Results showed that relationships between cumulative microbial respiration of different soils and soil temperature could be explained by exponential functions, which had P values lower than 0.001. The coefficient of temperature sensitivity (Q10 value) varied from 1.762 to 1.895. The Q10 value of cumulative microbial respiration decreased with the increase of soil temperature for all soils. The Q10 value of microbial respiration on 27 days after incubation was close to that of 1 day after incubation, indicating that the temperature sensitivity of recalcitrant organic carbon may be similar to that of labile organic carbon. For all soils, a highly significant ( P = 0.003 ) linear relationship between cumulative soil microbial respiration and soil DOC content could be observed. Soil DOC content could explain 31.6% variances of cumulative soil microbial respiration. For the individual soil and all soils, the relationship between cumulative soil microbial respiration and invertase activity could be explained by a highly significant (P < 0.01) linear regression function, which suggested that invertase was a good indicator of the magnitude of soil microbial respiration. PMID:26164932

  16. A multi-time scale, non-linear approach to understanding soil respiration

    NASA Astrophysics Data System (ADS)

    Nickerson, N. R.; Phillips, C.; Risk, D. A.

    2010-12-01

    To understand the processes that drive soil respiration and to make accurate predictions about global carbon cycling and potential climate feedbacks, it is critical that we develop accurate models that are useful on a range of timescales. There is, however, little agreement on the functional form and parameters that should be associated with modeling total soil respiration. Field data provides the most realistic platform for this assessment, but the environmental controls on soil respiration have been difficult to estimate in the field with good accuracy due to a combination of factors, including: (1) physical and biological uncertainties that are present in the field (ie. heat and gas diffusion, nutrient and substrate limitation); (2) the absence of a standardized and theoretically sound method for calculating model parameters using field data, and; (3) the absence of suitable long term, high temporal resolution respiration data from field studies, which is now becoming more available. This research focuses on multi-time scale non-linear analysis techniques, and their role in guiding the development of new soil respiration models that accurately predict respiration on a range of timescales. Using a physical model as a proxy of real world conditions, we focus on the confounding effect of physical factors, such as heat and gas diffusion and CO2 production depth, which have been found to be the cause of a considerable amount of error in past studies. Preliminary results show that for estimating temperature sensitivity, the non-linear approach is the best (compared to the typical log transform linear approach) in all circumstances, although caution should be exercised when analyzing short time series (i.e. diel) data because the lag and damping cause by gas diffusion may affect estimates. This work also examines moisture sensitivity parameters and the confounding effects of moisture on temperature sensitivity estimates. Finally we provide an evaluation of temporal

  17. Amplification and dampening of soil respiration by changes in temperature variability

    USGS Publications Warehouse

    Sierra, C.A.; Harmon, M.E.; Thomann, E.; Perakis, S.S.; Loescher, H.W.

    2011-01-01

    Accelerated release of carbon from soils is one of the most important feed backs related to anthropogenically induced climate change. Studies addressing the mechanisms for soil carbon release through organic matter decomposition have focused on the effect of changes in the average temperature, with little attention to changes in temperature vari-ability. Anthropogenic activities are likely to modify both the average state and the variability of the climatic system; therefore, the effects of future warming on decomposition should not only focus on trends in the average temperature, but also variability expressed as a change of the probability distribution of temperature.Using analytical and numerical analyses we tested common relationships between temperature and respiration and found that the variability of temperature plays an important role determining respiration rates of soil organic matter. Changes in temperature variability, without changes in the average temperature, can affect the amount of carbon released through respiration over the long term. Furthermore, simultaneous changes in the average and variance of temperature can either amplify or dampen there release of carbon through soil respiration as climate regimes change. The effects depend on the degree of convexity of the relationship between temperature and respiration and the magnitude of the change in temperature variance. A potential consequence of this effect of variability would be higher respiration in regions where both the mean and variance of temperature are expected to increase, such as in some low latitude regions; and lower amounts of respiration where the average temperature is expected to increase and the variance to decrease, such as in northern high latitudes.

  18. Coupling aboveground and belowground activities using short term fluctuations in 13C composition of soil respiration

    NASA Astrophysics Data System (ADS)

    Epron, D.; Parent, F.; Grossiord, C.; Plain, C.; Longdoz, B.; Granier, A.

    2011-12-01

    There is a growing amount of evidence that belowground processes in forest ecosystems are tightly coupled to aboveground activities. Soil CO2 efflux, the largest flux of CO2 to the atmosphere, is dominated by root respiration and by respiration of microorganisms that find the carbohydrates required to fulfil their energetic costs in the rhizosphere. A close coupling between aboveground photosynthetic activity and soil CO2 efflux is therefore expected. The isotopic signature of photosynthates varies with time because photosynthetic carbon isotope discrimination is dynamically controlled by environmental factors. This temporal variation of δ13C of photosynthate is thought to be transferred along the tree-soil continuum and it will be retrieved in soil CO2 efflux after a time lag that reflects the velocity of carbon transport from canopy to belowground. However, isotopic signature of soil CO2 efflux is not solely affected by photosynthetic carbon discrimination, bur also by post photosynthetic fractionation, and especially by fractionation processes affecting CO2 during the transport from soil layers to surface. Tunable diode laser spectrometry is a useful tool to quantify short-term variation in δ13C of soil CO2 efflux and of CO2 in the soil atmosphere. We set up hydrophobic tubes to measure the vertical profile of soil CO2 concentration and its δ13C composition in a temperate beech forest, and we monitored simultaneously δ13C of trunk and soil CO2 efflux, δ13C of phloem exudate and δ13C of leaf sugars. We evidenced that temporal changes in δ13C of soil CO2 and soil CO2 efflux reflected changes in environmental conditions that affect photosynthetic discrimination and that soil CO2 was 4.4% enriched compared to soil CO2 efflux according to diffusion fractionation. However, this close coupling can be disrupted when advective transport of CO2 took place. We also reported evidences that temporal variations in the isotopic composition of soil CO2 efflux reflect

  19. Soil respiration in tropical seasonal forest of Southern Vietnam

    NASA Astrophysics Data System (ADS)

    Avilov, Vitaly; Anichkin, Alexandr; Descherevskaya, Olga; Evdokimova, Elena; Nguyen Van, Thinh; Novichonok, Artyom; Do Phong, Luu; Kurbatova, Julia; Lopes de Gerenyu, Valentin

    2013-04-01

    Soil respiration was monitored as a part of a complex research of carbon balance in Nam Cat Tien National Park in Southern Vietnam (NCT site in AsiaFlux index). The study area is described as a tropical monsoon valley tall-stand forest at altitude about 156 m above sea level, mean annual air temperature is 26.2°C, with fluctuations of monthly averaged temperatures within 4°C; mean annual precipitation is 2470 mm with a distinct alternation of wet and dry seasons (Dong Phu weather station, 1976-1990). Measurements were made every 10-15 days during year 2012 at 6 plots that differ in soil and forest type, mostly in Lagerstroemia- or Dipterocarpus-dominated tree stands. Five chambers Ø162 mm were installed at each plot. CO2 concentration was defined with LI-820 gas analyser and 20 ml syringes (three syringes/samples per chamber) up to August 2012, and by means of closed-loop continuous field analysis from August on. Our studies have shown significant temporal and spatial variability of soil respiration in tropical rainforest. Namely, highest annual CO2 efflux rates were calculated for cambisols under lagerstroemia-dominated tree stand and for light sandy fluvisols under dipterocarpus-dominated tree stand (1694.3±546.0 and 1628.1±442.7 gC•m-2•y-1 respectively). Noteworthy is that the content of organic carbon in these soils varies utterly. Lowest annual CO2 efflux rate was calculated for clay-slate leptosols under dipterocarpus-dominated tree stand (972.7±716.5 gC•m-2•y-1). We also observed a significant impact of termites activity on site-scale spatial variability of soil respiration. Seasonal patterns of soil respiration rates were conformed for all plots except one on sandy soils. The beginning of rainy season in April did not result in higher soil respiration rates, but rates did rise in August - October, at the end of rainy season. Apparently this pattern is related to the accumulation of decomposed organic matter in soil and to the deficient

  20. Response of soil microbial respiration to varying temperature and moisture in three soils from the Siberian Arctic

    NASA Astrophysics Data System (ADS)

    Dunn, S.; Bunn, A. G.; Schade, J. D.; Polaris Project

    2011-12-01

    The climate of the Arctic is warming at a disproportionately higher rate as compared to the lower latitudes. Temperature and, by association, soil moisture are two of the most important variables that affect the respiration of soil microbial communities. The long-term storage of carbon in terrestrial systems relies upon low rates of soil microbial respiration at high latitudes, and an increase in temperature is thought to increase these rates. However, different ecosystems should respond uniquely to changes in temperature and moisture because of their historic microbial communities. Using mason jars in the laboratory, I experimentally manipulated the temperature and moisture of soils from three distinct arctic ecosystem types (tundra, taiga, and grazed floodplain). The goal of this experimental manipulation was to see if there are differences between these systems in their response to changes in their environment. I found that temperature significantly impacts microbial respiration (μg CO2 gOM-1 min-1) at all sites (p<0.001). In addition, there is a significant interaction between temperature and moisture at each site (p<0.001). However, the tundra site showed a stronger response in respiration with changes to temperature than the other two sites, as well as the strongest interaction between temperature and moisture (βtemperature= 1.5E10 -3; βinteraction= 1.9E10 -3). These findings are consistent with other observations that the soil microbial communities of the tundra grassland might be especially sensitive to warming.

  1. Soil Microbial Biomass, Basal Respiration and Enzyme Activity of Main Forest Types in the Qinling Mountains

    PubMed Central

    Cheng, Fei; Peng, Xiaobang; Zhao, Peng; Yuan, Jie; Zhong, Chonggao; Cheng, Yalong; Cui, Cui; Zhang, Shuoxin

    2013-01-01

    Different forest types exert essential impacts on soil physical-chemical characteristics by dominant tree species producing diverse litters and root exudates, thereby further regulating size and activity of soil microbial communities. However, the study accuracy is usually restricted by differences in climate, soil type and forest age. Our objective is to precisely quantify soil microbial biomass, basal respiration and enzyme activity of five natural secondary forest (NSF) types with the same stand age and soil type in a small climate region and to evaluate relationship between soil microbial and physical-chemical characters. We determined soil physical-chemical indices and used the chloroform fumigation-extraction method, alkali absorption method and titration or colorimetry to obtain the microbial data. Our results showed that soil physical-chemical characters remarkably differed among the NSFs. Microbial biomass carbon (Cmic) was the highest in wilson spruce soils, while microbial biomass nitrogen (Nmic) was the highest in sharptooth oak soils. Moreover, the highest basal respiration was found in the spruce soils, but mixed, Chinese pine and spruce stands exhibited a higher soil qCO2. The spruce soils had the highest Cmic/Nmic ratio, the greatest Nmic/TN and Cmic/Corg ratios were found in the oak soils. Additionally, the spruce soils had the maximum invertase activity and the minimum urease and catalase activities, but the maximum urease and catalase activities were found in the mixed stand. The Pearson correlation and principle component analyses revealed that the soils of spruce and oak stands obviously discriminated from other NSFs, whereas the others were similar. This suggested that the forest types affected soil microbial properties significantly due to differences in soil physical-chemical features. PMID:23840671

  2. Soil microbial biomass, basal respiration and enzyme activity of main forest types in the Qinling Mountains.

    PubMed

    Cheng, Fei; Peng, Xiaobang; Zhao, Peng; Yuan, Jie; Zhong, Chonggao; Cheng, Yalong; Cui, Cui; Zhang, Shuoxin

    2013-01-01

    Different forest types exert essential impacts on soil physical-chemical characteristics by dominant tree species producing diverse litters and root exudates, thereby further regulating size and activity of soil microbial communities. However, the study accuracy is usually restricted by differences in climate, soil type and forest age. Our objective is to precisely quantify soil microbial biomass, basal respiration and enzyme activity of five natural secondary forest (NSF) types with the same stand age and soil type in a small climate region and to evaluate relationship between soil microbial and physical-chemical characters. We determined soil physical-chemical indices and used the chloroform fumigation-extraction method, alkali absorption method and titration or colorimetry to obtain the microbial data. Our results showed that soil physical-chemical characters remarkably differed among the NSFs. Microbial biomass carbon (Cmic) was the highest in wilson spruce soils, while microbial biomass nitrogen (Nmic) was the highest in sharptooth oak soils. Moreover, the highest basal respiration was found in the spruce soils, but mixed, Chinese pine and spruce stands exhibited a higher soil qCO2. The spruce soils had the highest Cmic/Nmic ratio, the greatest Nmic/TN and Cmic/Corg ratios were found in the oak soils. Additionally, the spruce soils had the maximum invertase activity and the minimum urease and catalase activities, but the maximum urease and catalase activities were found in the mixed stand. The Pearson correlation and principle component analyses revealed that the soils of spruce and oak stands obviously discriminated from other NSFs, whereas the others were similar. This suggested that the forest types affected soil microbial properties significantly due to differences in soil physical-chemical features. PMID:23840671

  3. Winter soil CO2 efflux and its contribution to annual soil respiration in different ecosystems of Ebinur Lake Area

    NASA Astrophysics Data System (ADS)

    Qin, L.; Lv, G. H.; He, X. M.; Yang, J. J.; Wang, H. L.; Zhang, X. N.; Ma, H. Y.

    2015-08-01

    Arid and semiarid areas account for about one-third of the total land surface, and which play an important role in the global carbon cycle and climate system. However, up to now, compare with plenty knowledge information on winter soil efflux of forest ecosystems in mid-latitude ecosystems, winter soil efflux of arid areas at mid-latitude ecosystems is scare, Ebinur Lake Area, which is the study area of the present study, is located in arid regions of Northern China, with a vulnerable ecological environment suffering from extreme weather and climate. The objectives of this study were: (1) measure the winter soil respiration rate in our study area and determine its major environmental factors; (2) determine the winter soil CO2 efflux and its contribution to annual soil CO2 efflux in different ecosystems; and (3) discuss the estimated method of soil respiration that is most suitable to arid areas. We measured winter soil CO2 efflux and the associated environment factors in a farmland ecosystem (50a and 9a cotton fields), an abandoned land ecosystem (7a and 3a abandoned lands) and desert ecosystem ( Populus euphratica, Phragmites australis communities and sandy desert) in Ebinur Lake Area, China. The average winter soil respiration rate in the arid areas in the mid-latitude was 0.063 μmol m-2 s-1 to 0.730 μmol m-2 s-1. Specifically, the average winter soil respiration rate in the farmland ecosystems, abandoned land ecosystems and desert ecosystems were 0.686 μmol m-2 s-1, 0.443 μmol m-2 s-1 and 0.276 μmol m-2 s-1, respectively. Range of annual Q 10 (known as the increase in soil respiration rate per 10°C increase in temperature) in the three ecosystems were 0.989 to 4.962, 1.971 to 2.096 and 0.947 to 5.173, respectively. The relatively higher Q 10 values in the different ecosystems were all obtained in winter. We found that water (in the form of soil moisture or atmospheric humidity) was the primary factor that affected the change of soil respiration rate in the

  4. The moisture response of soil heterotrophic respiration: Interaction with soil properties.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil moisture-respiration functions are used to simulate the various mechanisms determining the relations between soil moisture content and carbon mineralization. Soil models used in the simulation of global carbon fluxes often apply simplified functions assumed to represent an average moisture-resp...

  5. [Priming Effects of Soil Moisture on Soil Respiration Under Different Tillage Practices].

    PubMed

    Zhang, Yan; Liang, Ai-zhen; Zhang, Xiao-ping; Chen, Sheng-long; Sun, Bing-jie; Liu, Si-yi

    2016-03-15

    In the early stage of an incubation experiment, soil respiration has a sensitive response to different levels of soil moisture. To investigate the effects of soil moisture on soil respiration under different tillage practices, we designed an incubation trial using air-dried soil samples collected from tillage experiment station established on black soils in 2001. The tillage experiment consisted of no-tillage (NT), ridge tillage (RT), and conventional tillage (CT). According to field capacity (water-holding capacity, WHC), we set nine moisture levels including 30%, 60%, 90%, 120%, 150%, 180%, 210%, 240%, 270% WHC. During the 22-day short-term incubation, soil CO₂ emission was measured. In the early stage of incubation, the priming effects occurred under all tillage practices. There were positive correlations between soil respiration and soil moisture. In addition to drought and flood conditions, soil CO₂ fluxes followed the order of NT > RT > CT. We fitted the relationship between soil moisture and soil CO₂ fluxes under different tillage practices. In the range of 30%-270% WHC, soil CO₂ fluxes and soil moisture fitted a quadratic regression equation under NT, and linear regression equations under RT and CT. Under the conditions of 30%-210% WHC of both NT and RT, soil CO₂ fluxes and soil moisture were well fitted by the logarithmic equation with fitting coefficient R² = 0.966 and 0.956, respectively.

  6. Divergent Effects of Nitrogen Addition on Soil Respiration in a Semiarid Grassland

    PubMed Central

    Zhu, Cheng; Ma, Yiping; Wu, Honghui; Sun, Tao; La Pierre, Kimberly J.; Sun, Zewei; Yu, Qiang

    2016-01-01

    Nitrogen (N) deposition has been steadily increasing for decades, with consequences for soil respiration. However, we have a limited understanding of how soil respiration responds to N availability. Here, we investigated the soil respiration responses to low and high levels of N addition (0.4 mol N m−2 yr−1 vs 1.6 mol N m−2 yr−1) over a two-year period in a semiarid Leymus chinensis grassland in Inner Mongolia, China. Our results show that low-level N addition increased soil respiration, plant belowground biomass and soil microbial biomass carbon (MBC), while high-level N additions decreased them. Soil respiration was positively correlated with plant belowground biomass, MBC, soil temperature and soil moisture. Together plant belowground biomass and MBC explained 99.4% of variation in mean soil respiration, with plant belowground biomass explaining 63.4% of the variation and soil MBC explaining the remaining 36%. Finally, the temperature sensitivity of soil respiration was not influenced by N additions. Overall, our results suggest that low levels of N deposition may stimulate soil respiration, but large increases in N availability may decrease soil respiration, and that these responses are driven by the dissimilar responses of both plant belowground biomass and soil MBC. PMID:27629241

  7. Divergent Effects of Nitrogen Addition on Soil Respiration in a Semiarid Grassland.

    PubMed

    Zhu, Cheng; Ma, Yiping; Wu, Honghui; Sun, Tao; La Pierre, Kimberly J; Sun, Zewei; Yu, Qiang

    2016-01-01

    Nitrogen (N) deposition has been steadily increasing for decades, with consequences for soil respiration. However, we have a limited understanding of how soil respiration responds to N availability. Here, we investigated the soil respiration responses to low and high levels of N addition (0.4 mol N m(-2) yr(-1) vs 1.6 mol N m(-2) yr(-1)) over a two-year period in a semiarid Leymus chinensis grassland in Inner Mongolia, China. Our results show that low-level N addition increased soil respiration, plant belowground biomass and soil microbial biomass carbon (MBC), while high-level N additions decreased them. Soil respiration was positively correlated with plant belowground biomass, MBC, soil temperature and soil moisture. Together plant belowground biomass and MBC explained 99.4% of variation in mean soil respiration, with plant belowground biomass explaining 63.4% of the variation and soil MBC explaining the remaining 36%. Finally, the temperature sensitivity of soil respiration was not influenced by N additions. Overall, our results suggest that low levels of N deposition may stimulate soil respiration, but large increases in N availability may decrease soil respiration, and that these responses are driven by the dissimilar responses of both plant belowground biomass and soil MBC. PMID:27629241

  8. The responses of soil and rhizosphere respiration to simulated climatic changes vary by season.

    PubMed

    Suseela, Vidya; Dukes, Jeffrey S

    2013-02-01

    Responses of soil respiration (Rs) to anthropogenic climate change will affect terrestrial carbon storage and, thus, feed back to warming. To provide insight into how warming and changes in precipitation regimes affect the rate and temperature sensitivity of Rs and rhizosphere respiration (Rr) across the year, we subjected a New England old-field ecosystem to four levels of warming and three levels of precipitation (ambient, drought, and wet treatments). We measured Rs and heterotrophic respiration (Rh) monthly (in areas of the plots with and without plants, respectively) and estimated Rr by calculating the difference in respiration between Rs and Rh. Even in this mesic ecosystem, Rs and Rr responded strongly to the precipitation treatments. Drought reduced Rs and Rr, both annually and during the growing season. Annual cumulative Rs responded nonlinearly to precipitation treatments; both drought and supplemental precipitation suppressed Rs compared to the ambient treatment. Warming increased Rs and Rr in spring and winter when soil moisture was optimal but decreased these rates in summer when moisture was limiting. Cumulative winter Rr increased by about 200% in the high warming (approximately 3.5 degrees C) treatment. The effect of climate treatments on the temperature sensitivity of Rs depended on the season. In the fall, the drought treatment decreased apparent Q10 relative to the other precipitation treatments. The responses of Rs to warming and altered precipitation were largely driven by changes in Rr. We emphasize the importance of incorporating realistic soil moisture responses into simulations of soil carbon fluxes; the long-term effects of warming on carbon--climate feedback will depend on future precipitation regimes. Our results highlight the nonlinear responses of soil respiration to soil moisture and, to our knowledge, quantify for the first time the loss of carbon through winter rhizosphere respiration due to warming. While this additional loss is

  9. The responses of soil and rhizosphere respiration to simulated climatic changes vary by season.

    PubMed

    Suseela, Vidya; Dukes, Jeffrey S

    2013-02-01

    Responses of soil respiration (Rs) to anthropogenic climate change will affect terrestrial carbon storage and, thus, feed back to warming. To provide insight into how warming and changes in precipitation regimes affect the rate and temperature sensitivity of Rs and rhizosphere respiration (Rr) across the year, we subjected a New England old-field ecosystem to four levels of warming and three levels of precipitation (ambient, drought, and wet treatments). We measured Rs and heterotrophic respiration (Rh) monthly (in areas of the plots with and without plants, respectively) and estimated Rr by calculating the difference in respiration between Rs and Rh. Even in this mesic ecosystem, Rs and Rr responded strongly to the precipitation treatments. Drought reduced Rs and Rr, both annually and during the growing season. Annual cumulative Rs responded nonlinearly to precipitation treatments; both drought and supplemental precipitation suppressed Rs compared to the ambient treatment. Warming increased Rs and Rr in spring and winter when soil moisture was optimal but decreased these rates in summer when moisture was limiting. Cumulative winter Rr increased by about 200% in the high warming (approximately 3.5 degrees C) treatment. The effect of climate treatments on the temperature sensitivity of Rs depended on the season. In the fall, the drought treatment decreased apparent Q10 relative to the other precipitation treatments. The responses of Rs to warming and altered precipitation were largely driven by changes in Rr. We emphasize the importance of incorporating realistic soil moisture responses into simulations of soil carbon fluxes; the long-term effects of warming on carbon--climate feedback will depend on future precipitation regimes. Our results highlight the nonlinear responses of soil respiration to soil moisture and, to our knowledge, quantify for the first time the loss of carbon through winter rhizosphere respiration due to warming. While this additional loss is

  10. Quantifying Components of Soil Respiration and Their Response to Abiotic Factors in Two Typical Subtropical Forest Stands, Southwest China

    PubMed Central

    Yu, Lei; Wang, Yujie; Wang, Yunqi; Sun, Suqi; Liu, Liziyuan

    2015-01-01

    Separating the components of soil respiration and understanding the roles of abiotic factors at a temporal scale among different forest types are critical issues in forest ecosystem carbon cycling. This study quantified the proportions of autotrophic (RA) and heterotrophic (RH) in total soil (RT) respiration using trenching and litter removal. Field studies were conducted in two typical subtropical forest stands (broadleaf and needle leaf mixed forest; bamboo forest) at Jinyun Mountain, near the Three Georges Reservoir in southwest China, during the growing season (Apr.–Sep.) from 2010 to 2012. The effects of air temperature (AT), soil temperature (ST) and soil moisture (SM) at 6cm depth, solar radiation (SR), pH on components of soil respiration were analyzed. Results show that: 1) SR, AT, and ST exhibited a similar temporal trend. The observed abiotic factors showed slight interannual variability for the two forest stands. 2) The contributions of RH and RA to RT for broadleaf and needle leaf mixed forest were 73.25% and 26.75%, respectively, while those for bamboo forest were 89.02% and 10.98%, respectively; soil respiration peaked from June to July. In both stands, CO2 released from the decomposition of soil organic matter (SOM), the strongest contributor to RT, accounted for over 63% of RH. 3) AT and ST were significantly positively correlated with RT and its components (p<0.05), and were major factors affecting soil respiration. 4) Components of soil respiration were significantly different between two forest stands (p<0.05), indicating that vegetation types played a role in soil respiration and its components. PMID:25680112

  11. [Dynamic changes in soil respiration components and their regulating factors in the Moso bamboo plantation in subtropical China].

    PubMed

    Yang, Wen-jia; Li, Yong-fu; Jiang, Pei-kun; Zhou, Guo-mo; Liu, Juan

    2015-10-01

    Dynamic changes (from April 2013 to March 2014) in soil respiration components were investigated by Li-8100 in the Moso bamboo plantation in Lin' an City, Zhejiang Province. Results showed that the average annual values for the soil total respiration rate, heterotrophic respiration rate, and autotrophic respiration rate in the Moso bamboo plantation were 2.93, 1.92 and 1.01 imol CO2 . m-2 . s-1, respectively. The soil respiration rate and its components exhibited strongly a seasonal dynamic pattern. The maximum appeared in July 2013, and the minimum appeared in January 2014. The annual cumulative CO2 emissions through soil respiration, heterotrophic respiration, and autotrophic respiration were 37.25, 24.61 and 12.64 t CO2 . hm-2 . a-1, respectively. The soil respiration and its components showed a close relation with soil temperature of 5 cm depth, and the corresponding Q10, values at 5 cm depth were 2.05, 1.95 and 2.34, respectively. Both the soil respiration and heterotrophic respiration were correlated to soil water soluble organic C (WSOC) content, but no significant relationship between autotrophic respiration and WSOC was observed. There were no significant relationships between soil respiration components and soil moisture content or microbial biomass C. The seasonal changes in soil respiration components in the Moso bamboo plantation were predominantly controlled by the soil temperature, and the soil WSOC content was an important environmental factor controlling total soil respiration and soil heterotrophic respiration. PMID:26995900

  12. Continuous Monitoring of Soil Respiration in Black Spruce Forest Soils, Interior Alaska

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Kim, S.; Kim, W.

    2009-12-01

    This research was carried out to estimate the continuous monitoring of soil respiration using automatic chamber system that was equipped with a control system, a compressor, and seven chambers (50 cm diameter, 30 cm high) set in sphagnum moss, feather moss, lichen, and tussock in black spruce forest soils, interior Alaska during growing season of 2008. The average daily soil respirations were 0.050±0.012 (standard deviation, CV 23%), 0.022±0.020 (91%), 0.082±0.035 (43%), and 0.027±0.010 mgCO2/m2/s (37%) in lichens, sphagnum moss, tussock and feather moss on black spruce forest soils with light chamber made by transparent material. The temporal variation of soil respiration in different vegetation types on black spruce forest soils during the growing season of 2008 is shown in Figure 1. The accumulative daily soil respiration was 5.2, 9.5, 2.3, and 2.8 mgCO2/m2/s in lichen, tussock, sphagnum moss, and feather moss of black spruce forest ground during the growing periods of 103 days, 2008 (Figure 2). Therefore, averaged regional soil respiration rate is 0.19±0.18 and 0.12±0.08 kgC/m2/(growing season) of 2007 and 2008 in black spruce forest soils, interior Alaska. The winter soil respiration was 0.049±0.013 gC/m2/(winter season), corresponding from 21±7% to 29±13% of the annual CO2 emitted from black spruce forest soils, interior Alaska.

  13. Response of Soil Respiration to Repeated Extreme Events in a Temperate Beech Forest in Austria

    NASA Astrophysics Data System (ADS)

    Leitner, S.; Kobler, J.; Holtermann, C.; Zechmeister-Boltenstern, S.; Saronjic, N.; Zimmermann, M.

    2015-12-01

    Climate change research predicts an increase in weather extremes like severe droughts and heavy rainfalls in central Europe. Since soil moisture is one of the most important drivers of soil respiration, a change in precipitation regime is likely to influence ecosystem C cycling. During drying of soils, soil microbial activity decreases and dead microbial cells, osmolytes, and semi-decomposed organic matter accumulate. When dry soils are rewetted, this easily-decomposable C leads to a pulse in soil respiration, a phenomenon known as "Birch-effect". In terms of annual soil CO2emissions, it is not clear whether these post-wetting respiration pulses outweigh or even overcompensate preceding drought-induced reductions in soil respiration. To investigate the impact of repeated drought and heavy rainfall events, a two-year precipitation manipulation experiment was conducted in an Austrian beech forest. Experimental plots were covered with transparent roofs to exclude rainfall, and an irrigation system was used to simulate heavy rainfall events. Control plots received natural precipitation. Soil respiration was monitored 3-hourly with an automatic static chamber system connected to an infrared CO2 analyzer. Soil temperature (Tsoil) and volumetric water content (VWC) were recorded with a datalogger. Various statistical models were tested to describe the relationship between soil respiration, Tsoiland VWC. Our results showed that repeated extreme events strongly reduced variation in soil respiration. Droughts significantly reduced soil respiration, and reductions depended on the length of the drought period. Post-wetting respiration pulses did not outweigh drought-induced reductions. Temperature sensitivity of soil respiration was best described with a Lloyd & Taylor model. Furthermore, in stressed plots VWC became limiting for soil respiration. Overall, our data corroborate the importance of the precipitation regime for soil respiration.

  14. [Soil respiration variations in winter wheat field in different previous crops and its influencing factors].

    PubMed

    Hao, Wang-Lin; Liang, Yin-Li; Wu, Xing; Lin, Xing-Jun; Zhu, Yan-Li; Luo, An-Rong

    2011-11-01

    This study was to define the Variations of soil respiration, the response of influence factors to soil respiration and carbon sink in the total growing season, in winter wheat field of different previous crops. The results showed that: (1) as soil depth increases, the response of temperature to soil respiration rate also increased with a lag; (2) the soil respiration rate was quadric to soil moisture, phosphorus, potassium, soil urease activity, soil temperature, soil moisture as the main factors had an effect on soil respiration rate; soil temperature had the stronger effect on soil respiration rate when potassium had the weaker effect on soil respiration rate; (3) the average carbon emission rate in wheat filed of different previous crops showed as follow: Pepper of previous crops > celery of previous crops > corn of previous crops > eggplant of previous crops. The intensity of carbon "sink" displayed as follow: eggplant of previous crops > celery of previous crops > corn of previous crops > pepper of previous crops. As for the trials of this study, although the soil respiration rate is highest in the winter wheat filed of previous pepper, the amount of carbon fixed is the most. Its ratio of net primary productivity (NPP) and soil carbon release quantity was highest, so carbon sink was the strongest. If rotation planting was arranged according to the purpose of increasing carbon sink and reducing carbon emissions, pepper was relatively appropriate stubbles crop, followed by corn crop, celery and eggplant.

  15. Can the gradient method improve our ability to predict soil respiration?

    NASA Astrophysics Data System (ADS)

    Phillips, Claire; Nickerson, Nicholas; Risk, Dave

    2015-04-01

    Soil surface flux measurements integrate respiration across steep vertical gradients of soil texture, moisture, temperature, and carbon substrates. Although there are benefits to integrating complex soil processes in a single surface measure, i.e. for constructing soil carbon budgets, one serious drawback of studying only surface respiration is the difficulty in generating predictive relationships from environmental drivers. For example, the relationship between depth-integrated soil respiration and temperature measured at a single discreet depth (apparent temperature sensitivity) can bear little resemblance to the temperature sensitivity of soil respiration within soil layers (actual temperature sensitivity). Here we present several examples of how the inferred environmental sensitivity of soil respiration can be improved from observations of CO2 flux profiles in contrast to surface fluxes alone. We present a theoretical approach for estimating the temperature sensitivity of soil respiration in situ, called the weighted heat flux approach, which avoids much of the hysteresis produced by typical respiration-temperature comparisons. The weighted heat flux approach gives more accurate estimates of within-soil temperature sensitivity, and is arguably the most theoretically robust analytical temperature model available. We also show how soil drying influences the effectiveness of the weighted heat flux approach, as well as the relative activity of discreet soil layers and specific soil organisms, such as mycorrhizal fungi. The additional information provided by within-soil flux profiles can improve the fidelity of both probabilistic and mechanistic soil respiration models

  16. Response of Soil Respiration to Grazing in an Alpine Meadow at Three Elevations in Tibet

    PubMed Central

    Fu, Gang; Zhang, Xianzhou; Yu, Chengqun; Shi, Peili; Zhou, Yuting; Li, Yunlong; Yang, Pengwan; Shen, Zhenxi

    2014-01-01

    Alpine meadows are one major type of pastureland on the Tibetan Plateau. However, few studies have evaluated the response of soil respiration (Rs) to grazing along an elevation gradient in an alpine meadow on the Tibetan Plateau. Here three fenced enclosures were established in an alpine meadow at three elevations (i.e., 4313 m, 4513 m, and 4693 m) in July 2008. We measured Rs inside and outside the three fenced enclosures in July–September, 2010-2011. Topsoil (0–20 cm) samples were gathered in July, August, and September, 2011. There were no significant differences for Rs, dissolved organic C (DOC), and belowground root biomass (BGB) between the grazed and ungrazed soils. Soil respiration was positively correlated with soil organic C (SOC), microbial biomass (MBC), DOC, and BGB. In addition, both Rs and BGB increased with total N (TN), the ratio of SOC to TN, ammonium N (NH4+-N), and the ratio of NH4+-N to nitrate N. Our findings suggested that the negligible response of Rs to grazing could be directly attributed to that of respiration substrate and that soil N may indirectly affect Rs by its effect on BGB. PMID:24790558

  17. Sensitivity of soil respiration to variability in soil moisture and temperature in a humid tropical forest.

    PubMed

    Wood, Tana E; Detto, Matteo; Silver, Whendee L

    2013-01-01

    Precipitation and temperature are important drivers of soil respiration. The role of moisture and temperature are generally explored at seasonal or inter-annual timescales; however, significant variability also occurs on hourly to daily time-scales. We used small (1.54 m(2)), throughfall exclusion shelters to evaluate the role soil moisture and temperature as temporal controls on soil CO2 efflux from a humid tropical forest in Puerto Rico. We measured hourly soil CO2 efflux, temperature and moisture in control and exclusion plots (n = 6) for 6-months. The variance of each time series was analyzed using orthonormal wavelet transformation and Haar-wavelet coherence. We found strong negative coherence between soil moisture and soil respiration in control plots corresponding to a two-day periodicity. Across all plots, there was a significant parabolic relationship between soil moisture and soil CO2 efflux with peak soil respiration occurring at volumetric soil moisture of approximately 0.375 m(3)/m(3). We additionally found a weak positive coherence between CO2 and temperature at longer time-scales and a significant positive relationship between soil temperature and CO2 efflux when the analysis was limited to the control plots. The coherence between CO2 and both temperature and soil moisture were reduced in exclusion plots. The reduced CO2 response to temperature in exclusion plots suggests that the positive effect of temperature on CO2 is constrained by soil moisture availability.

  18. Sensitivity of soil respiration to variability in soil moisture and temperature in a humid tropical forest.

    PubMed

    Wood, Tana E; Detto, Matteo; Silver, Whendee L

    2013-01-01

    Precipitation and temperature are important drivers of soil respiration. The role of moisture and temperature are generally explored at seasonal or inter-annual timescales; however, significant variability also occurs on hourly to daily time-scales. We used small (1.54 m(2)), throughfall exclusion shelters to evaluate the role soil moisture and temperature as temporal controls on soil CO2 efflux from a humid tropical forest in Puerto Rico. We measured hourly soil CO2 efflux, temperature and moisture in control and exclusion plots (n = 6) for 6-months. The variance of each time series was analyzed using orthonormal wavelet transformation and Haar-wavelet coherence. We found strong negative coherence between soil moisture and soil respiration in control plots corresponding to a two-day periodicity. Across all plots, there was a significant parabolic relationship between soil moisture and soil CO2 efflux with peak soil respiration occurring at volumetric soil moisture of approximately 0.375 m(3)/m(3). We additionally found a weak positive coherence between CO2 and temperature at longer time-scales and a significant positive relationship between soil temperature and CO2 efflux when the analysis was limited to the control plots. The coherence between CO2 and both temperature and soil moisture were reduced in exclusion plots. The reduced CO2 response to temperature in exclusion plots suggests that the positive effect of temperature on CO2 is constrained by soil moisture availability. PMID:24312508

  19. Investigation of soil carbon sequestration processes in a temperate deciduous forest using soil respiration experiments

    NASA Astrophysics Data System (ADS)

    Schütze, Claudia; Marañón-Jiménez, Sara; Zöphel, Hendrik; Gimper, Sebastian; Dienstbach, Laura; Garcia Quirós, Inmaculada; Cuntz, Matthias; Rebmann, Corinna

    2016-04-01

    Considering the carbon cycles of terrestrial ecosystems, soils represent a major long-term carbon storage pool. However, the storage capacity depends on several impact parameters based on biotic factors (e.g. vegetation activity, microbial activity, nutrient availability, interactions between vegetation and microbial activity) and abiotic driving factors (e.g. soil moisture, soil temperature, soil composition). Especially, increases in vegetation and microbial activity can lead to raised soil carbon release detectable as higher soil respiration rates. Within the frame of the ICOS project, several soil respiration experiments are under consideration at the temperate deciduous forest site "Hohes Holz" (Central Germany). These experiments started in May 2014. Soil respiration data acquisition was carried out using 8 automatic continuous chambers (LI-COR) and 60 different plots for bi-weekly survey chamber measurements in order to clarify the controlling factors for soil CO2 emissions such as litter availability, above- and belowground vegetation, and activation of microbial activity with temperature, soil moisture and root occurrence. Hence, several treatments (trenched, non-trenched, litter supply) were investigated on different plots within the research area. The data analysis of the 20-month observation period reveals preliminary results of the study. Obviously, significant differences between the trenched and the non-trenched plots concerning the CO2 emissions occurred. Increased soil carbon releases are supposed to be associated to the activation of microbial mineralization of soil organic matter by root inputs. Furthermore, depending on the amount of litter supply, different levels of activation were observed. The data of the continuous chamber measurements with a temporal resolution of one hour sampling interval can be used to show the dependence on above described biogeochemical processes due to abiotic controlling factors. Especially, soil moisture as a

  20. [Effects of simulated acid rain on respiration rate of cropland system with different soil pH].

    PubMed

    Zhu, Xue-zhu; Zhang, Gao-chuan; Li, Hui

    2009-10-15

    To evaluate the effects of acid rain on the respiration rate of cropland system, an outdoor pot experiment was conducted with paddy soils of pH 5.48 (S1), pH 6.70 (S1) and pH 8.18 (S3) during the 2005-2007 wheat-growing seasons. The cropland system was exposed to acid rain by spraying the wheat foliage and irrigating the soil with simulated rainwater of T1 (pH 6.0), T2 (pH 6.0, ionic concentration was twice as rainwater T1), and T3 (pH 4.4, ionic concentration was twice as rainwater T1), respectively. The static opaque chamber-gas chromatograph method was used to measure CO2 fluxes from cropland system. The results showed that acid rain affected the respiration rate of cropland system through crop plant, and the cropland system could adapt to acid rain. Acid rainwater significantly increased the average respiration rate in alkaline soil (S3) cropland system, while it had no significant effects on the average respiration rate in neutral soil (S2) and acidic soil (S1) cropland systems. During 2005-2006, after the alkaline soil cropland system was treated with rainwater T3, the average respiration rate was 23.6% and 27.6% higher than that of alkaline soil cropland system treated with rainwater T1 and T2, respectively. During March to April, the respiration rate was enhanced with the increase of rainwater ionic concentration, while it was dropped with the decrease of rainwater pH value in acidic soil cropland system. It was demonstrated that soil pH and crop plant played important roles on the respiration rate of cropland system.

  1. [Effects of simulated acid rain on respiration rate of cropland system with different soil pH].

    PubMed

    Zhu, Xue-zhu; Zhang, Gao-chuan; Li, Hui

    2009-10-15

    To evaluate the effects of acid rain on the respiration rate of cropland system, an outdoor pot experiment was conducted with paddy soils of pH 5.48 (S1), pH 6.70 (S1) and pH 8.18 (S3) during the 2005-2007 wheat-growing seasons. The cropland system was exposed to acid rain by spraying the wheat foliage and irrigating the soil with simulated rainwater of T1 (pH 6.0), T2 (pH 6.0, ionic concentration was twice as rainwater T1), and T3 (pH 4.4, ionic concentration was twice as rainwater T1), respectively. The static opaque chamber-gas chromatograph method was used to measure CO2 fluxes from cropland system. The results showed that acid rain affected the respiration rate of cropland system through crop plant, and the cropland system could adapt to acid rain. Acid rainwater significantly increased the average respiration rate in alkaline soil (S3) cropland system, while it had no significant effects on the average respiration rate in neutral soil (S2) and acidic soil (S1) cropland systems. During 2005-2006, after the alkaline soil cropland system was treated with rainwater T3, the average respiration rate was 23.6% and 27.6% higher than that of alkaline soil cropland system treated with rainwater T1 and T2, respectively. During March to April, the respiration rate was enhanced with the increase of rainwater ionic concentration, while it was dropped with the decrease of rainwater pH value in acidic soil cropland system. It was demonstrated that soil pH and crop plant played important roles on the respiration rate of cropland system. PMID:19968099

  2. [Effects of Green Manure Intercropping and Straw Mulching on Winter Rape Rhizosphere Soil Organic Carbon and Soil Respiration].

    PubMed

    Zhou, Quan; Wang, Long-chang; Xiong, Ying; Zhang, Sai; Du, Juan; Zhao, Lin-lu

    2016-03-15

    Under the background of global warming, the farmland soil respiration has become the main way of agricultural carbon emissions. And green manure has great potential to curb greenhouse gas emissions and achieve energy conservation and emissions reduction. However, in purple soil region of Southwest, China, soil respiration under green manure remains unclear, especially in the winter and intercropping. Through the green manure ( Chinese milk vetch) intercropping with rape, therefore, we compared the effects of rape rhizosphere under straw mulching. The soil organic carbon and soil respiration were examined. The results showed, compared with straw mulching, root separation was the major influencing factors of soil organic carbon on rape rhizosphere. Soil organic carbon was significantly decreased by root interaction. In addition, straw mulching promoted while green manure intercropping inhibited the soil respiration. Soil respiration presented the general characteristics of fall-rise-fall due to the strong influence of rape growth period. Therefore, it showed a cubic curve relationship with soil temperature.

  3. [Effects of Green Manure Intercropping and Straw Mulching on Winter Rape Rhizosphere Soil Organic Carbon and Soil Respiration].

    PubMed

    Zhou, Quan; Wang, Long-chang; Xiong, Ying; Zhang, Sai; Du, Juan; Zhao, Lin-lu

    2016-03-15

    Under the background of global warming, the farmland soil respiration has become the main way of agricultural carbon emissions. And green manure has great potential to curb greenhouse gas emissions and achieve energy conservation and emissions reduction. However, in purple soil region of Southwest, China, soil respiration under green manure remains unclear, especially in the winter and intercropping. Through the green manure ( Chinese milk vetch) intercropping with rape, therefore, we compared the effects of rape rhizosphere under straw mulching. The soil organic carbon and soil respiration were examined. The results showed, compared with straw mulching, root separation was the major influencing factors of soil organic carbon on rape rhizosphere. Soil organic carbon was significantly decreased by root interaction. In addition, straw mulching promoted while green manure intercropping inhibited the soil respiration. Soil respiration presented the general characteristics of fall-rise-fall due to the strong influence of rape growth period. Therefore, it showed a cubic curve relationship with soil temperature. PMID:27337908

  4. Soil respiration in a long-term tillage treatment experiment

    NASA Astrophysics Data System (ADS)

    Gelybó, Györgyi; Birkás, Márta; Dencsö, Márton; Horel, Ágota; Kása, Ilona; Tóth, Eszter

    2016-04-01

    Regular soil CO2 efflux measurements have been carried out at Józsefmajor longterm tillage experimental site in 2014 and 2015 with static chamber technique in no-till and ploughing plots in seven spatial replicates. The trial was established in 2002 on a loamy chernozem soil at the experimental site of the Szent István University nearby the city Hatvan, northern Hungary. At the site sunflower (Helianthus A.) and wheat (Triticum A.) was grown in 2014 and 2015, respectively. Ancillary measurements carried out at the site included weather parameters, soil water content, soil temperature. The aim of the investigation was to detect the effect of soil disturbance and soil tillage treatments on soil CO2 emission in agricultural ecosystems. Soil respiration measurements were carried out every week during the vegetation period and campaign measurements were performed scheduled to tillage application. In this latter case, measurements were carried out 1, 2, 3, 4, 6, 12, 18, 24, 48, 72, 96, 120 hours and 7 days after tillage operation. Results showed that during the vegetation season in the majority of measurement occasions emission was higher in the no-till plots. These differences; however were not found to be statistically significant. Due to the short term effect of tillage treatment, emissions increased following tillage treatment in the ploughed plots. Soil water content was also examined as main driver of soil CO2 fluxes. Soil water content sharply decreases in the surface layer (5-10 cm depth) after tillage treatment indicating a fast drying due to soil disturbance. This effect slowly attenuated and eventually extincted in approx. two weeks. CO2 emission measurements were associated with high uncertainties as a result of the measurement technique. Our further aim is to reduce this uncertainty using independent measurement techniques on the field.

  5. Permafrost collapse alters soil carbon stocks, respiration, CH4 , and N2O in upland tundra.

    PubMed

    Abbott, Benjamin W; Jones, Jeremy B

    2015-12-01

    Release of greenhouse gases from thawing permafrost is potentially the largest terrestrial feedback to climate change and one of the most likely to occur; however, estimates of its strength vary by a factor of thirty. Some of this uncertainty stems from abrupt thaw processes known as thermokarst (permafrost collapse due to ground ice melt), which alter controls on carbon and nitrogen cycling and expose organic matter from meters below the surface. Thermokarst may affect 20-50% of tundra uplands by the end of the century; however, little is known about the effect of different thermokarst morphologies on carbon and nitrogen release. We measured soil organic matter displacement, ecosystem respiration, and soil gas concentrations at 26 upland thermokarst features on the North Slope of Alaska. Features included the three most common upland thermokarst morphologies: active-layer detachment slides, thermo-erosion gullies, and retrogressive thaw slumps. We found that thermokarst morphology interacted with landscape parameters to determine both the initial displacement of organic matter and subsequent carbon and nitrogen cycling. The large proportion of ecosystem carbon exported off-site by slumps and slides resulted in decreased ecosystem respiration postfailure, while gullies removed a smaller portion of ecosystem carbon but strongly increased respiration and N2 O concentration. Elevated N2 O in gully soils persisted through most of the growing season, indicating sustained nitrification and denitrification in disturbed soils, representing a potential noncarbon permafrost climate feedback. While upland thermokarst formation did not substantially alter redox conditions within features, it redistributed organic matter into both oxic and anoxic environments. Across morphologies, residual organic matter cover, and predisturbance respiration explained 83% of the variation in respiration response. Consistent differences between upland thermokarst types may contribute to the

  6. Basal respiration - a proxy to understand spatial variability of soil CO2 emissions in urban regions

    NASA Astrophysics Data System (ADS)

    Vasenev, Viacheslav; Stoorvogel, Jetse; Ananyeva, Nadezhda; Ivashchenko, Kristina; Vizirskaya, Marya; Valentini, Riccardo

    2015-04-01

    Soil respiration (Rs) is an important terrestrial CO2 efflux and received significant attention at different scale levels. However, the sampling density is limited and global Rs databases are biased towards natural ecosystems and towards north America and Europe. This limits our understanding of the spatial variability of Rs. The methodological constraints of direct Rs measurements in the field limit the number of observations. As an alternative approach to approximate the spatial variability of Rs, we used basal respiration (BR) as an indirect measurement. First, the direct Rs and indirect BR measurements were compared at a 10 km2 test area in Moscow city, which included adjacent forests, croplands and urban lawn plots. Rs was monitored by in situ chamber approach with an IR Li-820 gas analyzer at 50 points during the growing season (June-October 2013, 9 time repetitions per point). In the same area, 32 locations were sampled and BR was measured under controlled conditions. Rs was affected by anthropogenic disturbance with the highest values in urban lawns. BR was mainly controlled by soil organic carbon (SOC) with maximum rates in the forested area. Total variability reported by direct observations was 10% higher, than one for BR, although the spatial variability captured by both approaches was similar confirmed by significant correlation between variance coefficients (CV) of the values. This shows that BR is a relevant proxy to analyze the spatial variability of Rs. Subsequently, the sampling area was expanded to the Moscow region for which respiration was mapped using digital soil mapping techniques and BR as a proxy for Rs. Although the absolute levels of respiration remained uncertain, the spatial patterns of BR are likely to correspond well with Rs patterns. Land use largely determined the spatial heterogeneity of soil respiration. Most variation occurred in the urban areas. BR is a relevant and straightforward proxy to understand patterns of Rs especially

  7. Topographic Distribution of Soil Respiration in Northern Hardwood Forests

    NASA Astrophysics Data System (ADS)

    Beall, F. D.; Bourbonniere, R. A.; Creed, I. F.

    2004-05-01

    Soil respiration is an important source of CO2 to the atmosphere and fluxes from complex terrains like those found in northern hardwood forests are not well documented. Our initial hypothesis was that the wetlands (swamps) at the bottom of such catchments would exhibit consistently less CO2 efflux than the upland components. To test this hypothesis we laid out transects along topographic gradients in each of two catchments at the Turkey Lakes Watershed near Sault Ste. Marie Ontario. Soil respiration was determined by the static non-steady state chamber method using an infrared gas analyser in the summer and fall of 2002 and spring to fall of 2003. Measurements of soil temperature, moisture and soil solution DOC concentrations were collected coincidentally with CO2 efflux measurements. Results indicate that a transition zone exists at the lower portions of the slopes in these high relief catchments that is characterized by higher CO2 efflux than the wetland or upland sites along the transects. The differences in CO2 efflux are greatest in mid summer, e.g. August 2003 mean values were 9, 7 and 3 micromoles CO2 m-2 sec-1 for the transition, upland and wetland zones respectively. Several topographic features (depressions, shelves, convergent and divergent foot slopes) populate the transition zone but collar placement did not specifically target them. Therefore statistical analysis was done on the three-position model defining the transition zone as simply the lower portion of the slope. On an annual basis the transition zone showed significantly greater effluxes of CO2 than either of the other two zones (P <0.005). Different topographic positions also exhibited differences in the relationships between CO2 efflux and soil temperature, soil moisture and soil solution DOC concentrations. This study shows that soil respiration can not be generalized without taking topographic position into consideration. Classification of catchments simply into "wetland" and "upland

  8. Soil moisture effects on the carbon isotopic composition of soil respiration

    EPA Science Inventory

    The carbon isotopic composition ( 13C) of recently assimilated plant carbon is known to depend on water-stress, caused either by low soil moisture or by low atmospheric humidity. Air humidity has also been shown to correlate with the 13C of soil respiration, which suggests indir...

  9. Research of the diurnal soil respiration dynamic in two typical vegetation communities in Tianjin estuarine wetland

    NASA Astrophysics Data System (ADS)

    Zhang, Q.; Meng, W. Q.; Li, H. Y.

    2016-08-01

    Understanding the differences and diurnal variations of soil respiration in different vegetation communities in coastal wetland is to provide basic reliable scientific evidence for the carbon "source" function of wetland ecosystems in Tianjin.Measured soil respiration rate which changed during a day between two typical vegetation communities (Phragmites australis, Suaeda salsa) in coastal wetland in October, 2015. Soil temperature and moisture were measured at the same time. Each of the diurnal curves of soil temperature in two communities had a single peak value, and the diurnal variations of soil moisture showed a "two peak-one valley" trend. The diurnal dynamic of soil respiration under the two communities had obvious volatility which showed a single peak form with its maximum between 12:00-14:00 and minimum during 18:00. The diurnal average of soil respiration rate in Phragmites australis communities was 3.37 times of that in Suaeda salsa communities. Significant relationships were found by regression analysis among soil temperature, soil moisture and soil respiration rate in Suaeda salsa communities. There could be well described by exponential models which was y = -0.245e0.105t between soil respiration rate and soil temperature, by quadratic models which was y = -0.276×2 + 15.277× - 209.566 between soil respiration rate and soil moisture. But the results of this study showed that there were no significant correlations between soil respiration and soil temperature and soil moisture in Phragmites australis communities (P > 0.05). Therefore, under the specific wetland environment conditions in Tianjin, soil temperature and moisture were not main factors influencing the diurnal variations of soil respiration rate in Phragmites australis communities.

  10. [Effects of simulated nitrogen deposition on soil respiration in northern subtropical deciduous broad-leaved forest].

    PubMed

    Hu, Zheng-hua; Li, Han-mao; Yang, Yan-ping; Chen, Shu-tao; Li, Cen-zi; Shen, Shuang-he

    2010-08-01

    To investigate the effects of elevated nitrogen deposition on forest soil respiration, a simulated nitrogen deposition field experiment was conducted in northern subtropical deciduous broad-leave forest from April 2008 to April 2009. Nitrogen treatments included the control (no N addition, CK), low-N [50 kg x (hm2 x a)(-1), T(L)], medium-N [100 kg x (hm2 x a)(-1), T(M)], and high-N [150 kg x (hm2 x a)(-1), T(H)]. The respiration rates were measured by a static chamber-gas chromatograph method. Results showed that nitrogen deposition did not change the seasonal and daily variation patterns of soil respiration. Compared to the control, T(L), T(M) and T(H) treatments reduced soil annual average respiration rates by 8.51%, 9.74% and 11.24%, respectively. Meanwhile, T(L), T(M) and T(H) treatments decreased daily average soil respiration rates by 4.42%, 11.09% and 12.17%, respectively. Significant relationship was found between soil respiration rate and soil temperature. The Q10 (temperature sensitivity coefficients) for soil respiration of CK, T(L), T(M), and T(H) treatments were 2.53, 3.22, 2.64 and 2.92, respectively. Our findings suggested that nitrogen deposition reduced soil respiration, and increased soil respiration temperature sensitivity in northern subtropical deciduous broad-leave forest.

  11. Influence of low- and high-frequency electrical heating on biodegrading microorganisms in soil: soil respiration.

    PubMed

    Roland, Ulf; Holzer, Frank; Kopinke, Frank-Dieter

    2013-01-01

    The influence of electrical heating on microbiological processes in soil has been studied to evaluate the potential for enhancing biodegradation of pollutants by controlling the temperature. A frequency of 50 Hz (power line frequency) was applied for resistive heating. Dielectric heating was realized using a frequency of 13.56 MHz (radio frequency). Both techniques were compared with conventional heating in a water bath. For experiments in laboratory and full scale, a model soil and a contaminated original soil were used. It was shown that under conditions capable for heating soil to 35 degrees C or even 60 degrees C, soil respiration as a measure for microbial activity was not hindered by electrical heating when temperature and moisture content were comparable with conventional heating. The variations of soil respiration were reversible upon temperature changes. Under certain conditions, periodical fluctuations of microbiological activity were observed. Several possible explanations including chronobiology are discussed without being able to provide an unambiguous interpretation for this effect.

  12. Wet meadow ecosystems contribute the majority of overwinter soil respiration from snow-scoured alpine tundra

    NASA Astrophysics Data System (ADS)

    Knowles, John F.; Blanken, Peter D.; Williams, Mark W.

    2016-04-01

    We measured soil respiration across a soil moisture gradient ranging from dry to wet snow-scoured alpine tundra soils throughout three winters and two summers. In the absence of snow accumulation, soil moisture variability was principally determined by the combination of mesotopographical hydrological focusing and shallow subsurface permeability, which resulted in a patchwork of comingled ecosystem types along a single alpine ridge. To constrain the subsequent carbon cycling variability, we compared three measures of effective diffusivity and three methods to calculate gradient method soil respiration from four typical vegetation communities. Overwinter soil respiration was primarily restricted to wet meadow locations, and a conservative estimate of the rate of overwinter soil respiration from snow-scoured wet meadow tundra was 69-90% of the maximum carbon dioxide (CO2) respired by seasonally snow-covered soils within this same catchment. This was attributed to higher overwinter soil temperatures at wet meadow locations relative to fellfield, dry meadow, and moist meadow communities, which supported liquid water and heterotrophic respiration throughout the winter. These results were corroborated by eddy covariance-based measurements that demonstrated an average of 272 g C m-2 overwinter carbon loss during the study period. As a result, we updated a conceptual model of soil respiration versus snow cover to express the potential for soil respiration variability from snow-scoured alpine tundra.

  13. Soil respiration in four different land use systems in north central Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Arevalo, Carmela B. M.; Bhatti, Jagtar S.; Chang, Scott X.; Jassal, Rachhpal S.; Sidders, Derek

    2010-03-01

    This study compares soil respiration and its heterotrophic and autotrophic components in four land use types: agriculture, 2 and 9 year old hybrid poplar plantations, grassland, and a native aspen stand in north central Alberta, Canada, over a period of two growing seasons (2006 and 2007). The differences were examined with respect to substrate quality and quantity, fine root biomass, and nutrient availability, in addition to soil temperature and soil water content. Cumulative soil C loss via soil respiration averaged over the two growing seasons was (in decreasing order) 781, 551, 523, 502, and 428 g C m-2 for native aspen stand, 9 year old hybrid poplar plantation, grassland, agriculture and 2 year old hybrid poplar plantation, respectively. We found that ˜75% of soil respiration in the native aspen stand originated from the top 7.5-10 cm litter-fibric-humus layer. Seasonal heterotrophic and autotrophic respiration among the land uses ranged from 97 to 272 and 333 to 560 g C m-2, respectively, contributing up to 35% and 83% of total soil respiration, respectively. The variability in soil respiration across different land uses was explained mainly by site differences in soil temperature (88-94%). Soil respiration followed a pronounced seasonal trend: increasing during the growing season and converging to a minimum in the fall. Soil respiration under different land uses was influenced by (1) ecosystem C stock, (2) temperature sensitivity (Q10) of organic matter present, and (3) organic matter decomposability as indicated by the natural abundance of δ13C. Heterotrophic respiration was influenced by soil temperature, while autotrophic respiration was influenced by fine root biomass and nutrient (NO3- and P) availability. These results are useful in estimating potential responses of soil respiration and its components to future land management and climate change.

  14. Contribution of root respiration to soil surface CO2 flux in a boreal black spruce chronosequence.

    PubMed

    Bond-Lamberty, Ben; Wang, Chuankuan; Gower, Stith T

    2004-12-01

    We quantified the contributions of root respiration (RC) and heterotrophic respiration to soil surface CO2 flux (RS) by comparing trenched and untrenched plots in well-drained and poorly drained stands of a black spruce (Picea mariana (Mill.) BSP) fire chronosequence in northern Manitoba, Canada. Our objectives were to: (1) test different equations for modeling RS as a function of soil temperature; and (2) model annual RS and RC for the chronosequence from continuous soil temperature measurements. The choice of equation to model RS strongly affected annual RS and RC, with an Arrhenius-based model giving the best fit to the data, especially at low temperatures. Modeled values of annual RS were positively correlated with soil temperature at 2-cm depth and were affected by year of burn and trenching, but not by soil drainage. During the growing season, measured RC was low in May, peaked in late July and declined to low values by the end of the growing season. Annual RC was < 5% of RS in the recently burned stands, approximately 40% in the 21-year-old stands and 5-15% in the oldest (152-year-old) stands. Evidence suggests that RC may have been underestimated in the oldest stands, with residual root decay from trenching accounting for 5-10% of trenched plot RS at most sites. PMID:15465701

  15. Soil respiration in a mixed temperate forest and its contribution to total ecosystem respiration.

    PubMed

    Curiel Yuste, J; Nagy, M; Janssens, I A; Carrara, A; Ceulemans, R

    2005-05-01

    Soil respiration (SR) was measured with an infrared gas analyzer in nine plots representative of the heterogeneous vegetation in a mixed coniferous-deciduous forest in the Belgian Campine region. Selected plots included the two most representative overstory species (Pinus sylvestris L. and Quercus robur L.) in combination with the most representative understory species of the forest. A model that includes temperature and water as the main controlling variables was fitted to the data. We found large spatial variability in SR among plots, with typically lower fluxes under the coniferous overstory than under the deciduous overstory (means of 4.8 +/- 0.4 and 8.8 +/- 0.5 Mg C ha(-1) year(-1), respectively). Total annual soil carbon (C) emissions were estimated by weighting fluxes from different types of vegetation according to their relative contribution to the footprint area of the eddy covariance flux measurement. The relative contribution of the two main tree species to the footprint-weighted total SR varied among seasons with the more abundant coniferous overstory contributing the most to total SR during most of the year. Nonetheless, during summer, the contribution of deciduous plots to total SR was disproportionally high because of the more pronounced seasonality of belowground metabolic activity. Net ecosystem carbon dioxide exchange was measured by eddy covariance, and we estimated total ecosystem respiration (TER) with footprint-constrained nighttime fluxes. Mean total annual SR and TER were 6.1 +/- 0.11 and 9.1 +/- 1.15 Mg C ha(-1) year(-1), respectively. The 95% confidence interval of the ratio of annual SR:TER ranged from 0.58 to 0.76, with a mean of 0.67. The contribution of SR to TER tended to vary seasonally, with minimum contributions during summer (less than 50% of TER) and maximum contributions during winter (about 94% of TER).

  16. Response of soil respiration to climate across biofuel crops and land use histories

    NASA Astrophysics Data System (ADS)

    Su, Y.; Chen, J.; Shao, C.; Shen, W.; Zenone, T.; John, R.; Deal, M.; Hamilton, S. K.; Robertson, G. P.

    2013-12-01

    Land use change (LUC) due to the worldwide increasing production of biofuel crops creates carbon debt that would require decades to repay. The payback time depends on the net ecosystem exchange (NEE) of CO2 and more determined by the carbon loss, such as soil respiration, than photosynthesis offset. Soil respiration is not only an important part of ecosystem respiration, but is also highly correlated with ecosystem production, via substrate subsidies from plants. Both autotrophic and heterotrophic soil respiration were regulated by climated-induced factors (e.g. soil temperature and soil water content) and also affected by substrate supply. In 2009, three sites in conservation reserve program (CRP) and conventional corn-soybean rotation agricultural lands (AG), were converted to soybean production, in experimental sites at Kellogg Biological Station, MI. In 2010, the three sites of differential previous land uses were then converted to corn (Cr), switchgrass (Sw) and prairie mixture (Pr) production. A reference site has been maintained CRP status since then. We used chamber-based method to assess total and heterotrophic soil respirations rate (SRRt and SRRh) from control treatment (C) and root exclusion treatment (E) at all sites, in 2011 and 2012, to explore how soil respiration rate (SRR) respond to the change of abiotic and biotic factors. Our results show that soil temperature (Ts) are important factors that affect SRR patterns. At the beginning of growing season, SRRs are low (average SRRt and SRRh are 3.19 and 3.11 umol CO2/m2s, respectively, on April 10th, 2011) when soil temperature is low. SRRs in general increased over time in a year, peaked in late July- early August, 1-2 weeks after soil temperature arrive its peak (maximum average SRRt and SRRh are 8.64 and 5.68, respectively, on August 3rd/4th, 2011). Soil water content (VWC) did not affect the time of SRR peak but limited its amount; when VWCs were extremely low in 2012 (average VWC at C and E

  17. Using O2 to study the relationships between soil CO2 efflux and soil respiration

    NASA Astrophysics Data System (ADS)

    Angert, A.; Yakir, D.; Rodeghiero, M.; Preisler, Y.; Davidson, E. A.; Weiner, T.

    2015-04-01

    Soil respiration is the sum of respiration processes in the soil and is a major flux in the global carbon cycle. It is usually assumed that the CO2 efflux is equal to the soil respiration rate. Here we challenge this assumption by combining measurements of CO2 with high-precision measurements of O2. These measurements were conducted on different ecosystems and soil types and included measurements of air samples taken from the soil profile of three Mediterranean sites: a temperate forest and two alpine forests. Root-free soils from the alpine sites were also incubated in the lab. We found that the ratio between the CO2 efflux and the O2 influx (defined as apparent respiratory quotient, ARQ) was in the range of 0.14 to 1.23 and considerably deviated from the value of 0.9 ± 0.1 expected from the elemental composition of average plants and soil organic matter. At the Mediterranean sites, these deviations are explained as a result of CO2 dissolution in the soil water and transformation to bicarbonate ions in these high-pH soils, as well as by carbonate mineral dissolution and precipitation processes. Thus, a correct estimate of the short-term, chamber-based biological respiratory flux in such soils can only be made by dividing the measured soil CO2 efflux by the average (efflux-weighted) soil profile ARQ. Applying this approach to a semiarid pine forest resulted in an estimated short-term biological respiration rate that is 3.8 times higher than the chamber-measured surface CO2. The ARQ values often observed in the more acidic soils were unexpectedly low (< 0.7). These values probably result from the oxidation of reduced iron, which has been formed previously during times of high soil moisture and local anaerobic conditions inside soil aggregates. The results reported here provide direct quantitative evidence of a large temporal decoupling between soil-gas exchange fluxes and biological soil respiration.

  18. Can plant phloem properties affect the link between ecosystem assimilation and respiration?

    NASA Astrophysics Data System (ADS)

    Mencuccini, M.; Hölttä, T.; Sevanto, S.; Nikinmaa, E.

    2012-04-01

    Phloem transport of carbohydrates in plants under field conditions is currently not well understood. This is largely the result of the lack of techniques suitable for measuring phloem physiological properties continuously under field conditions. This lack of knowledge is currently hampering our efforts to link ecosystem-level processes of carbon fixation, allocation and use, especially belowground. On theoretical grounds, the properties of the transport pathway from canopy to roots must be important in affecting the link between carbon assimilation and respiration, but it is unclear whether their effect is partially or entirely masked by processes occurring in other parts of the ecosystem. One can also predict the characteristic time scales over which these effects should occur and, as consequence, predict whether the transfer of turgor and osmotic signals from the site of carbon assimilation to the sites of carbon use are likely to control respiration. We will present two sources of evidence suggesting that the properties of the phloem transport system may affect processes that are dependent on the supply of carbon substrate, such as root or soil respiration. Firstly, we will summarize the results of a literature survey on soil and ecosystem respiration where the speed of transfer of photosynthetic sugars from the plant canopy to the soil surface was determined. Estimates of the transfer speed could be grouped according to whether the study employed isotopic or canopy soil flux-based techniques. These two groups provided very different estimates of transfer times likely because transport of sucrose molecules, and pressure-concentration waves, in phloem differed. Secondly, we will argue that simultaneous measurements of bark and xylem diameters provide a novel tool to determine the continuous variations of phloem turgor in vivo in the field. We will present a model that interprets these changes in xylem and live bark diameters and present data testing the model

  19. Soil respiration and bacterial structure and function after 17 years of a reciprocal soil transplant experiment

    DOE PAGES

    Bond-Lamberty, Benjamin; Bolton, Harvey; Fansler, Sarah J.; Heredia-Langner, Alejandro; Liu, Chongxuan; McCue, Lee Ann; Smith, Jeff L.; Bailey, Vanessa L.

    2016-03-02

    The effects of climate change on soil organic matter—its structure, microbial community, carbon storage, and respiration response—remain uncertain and widely debated. In addition, the effects of climate changes on ecosystem structure and function are often modulated or delayed, meaning that short-term experiments are not sufficient to characterize ecosystem responses. This study capitalized on a long-term reciprocal soil transplant experiment to examine the response of dryland soils to climate change. The two transplant sites were separated by 500 m of elevation on the same mountain slope in eastern Washington state, USA, and had similar plant species and soil types. We resampledmore » the original 1994 soil transplants and controls, measuring CO2 production, temperature response, enzyme activity, and bacterial community structure after 17 years. Over a laboratory incubation of 100 days, reciprocally transplanted soils respired roughly equal cumulative amounts of carbon as non-transplanted controls from the same site. Soils transplanted from the hot, dry, lower site to the cooler and wetter (difference of -5 °C monthly maximum air temperature, +50 mm yr-1precipitation) upper site exhibited almost no respiratory response to temperature (Q10 of 1.1), but soils originally from the upper, cooler site had generally higher respiration rates. The bacterial community structure of transplants did not differ significantly from that of untransplanted controls, however. Slight differences in local climate between the upper and lower Rattlesnake locations, simulated with environmental control chambers during the incubation, thus prompted significant differences in microbial activity, with no observed change to bacterial structure. Lastly, these results support the idea that environmental shifts can influence soil C through metabolic changes, and suggest that microbial populations responsible for soil heterotrophic respiration may be constrained in surprising ways, even

  20. Soil Respiration and Bacterial Structure and Function after 17 Years of a Reciprocal Soil Transplant Experiment

    PubMed Central

    Bond-Lamberty, Ben; Bolton, Harvey; Fansler, Sarah; Heredia-Langner, Alejandro; Liu, Chongxuan; McCue, Lee Ann; Bailey, Vanessa

    2016-01-01

    The effects of climate change on soil organic matter—its structure, microbial community, carbon storage, and respiration response—remain uncertain and widely debated. In addition, the effects of climate changes on ecosystem structure and function are often modulated or delayed, meaning that short-term experiments are not sufficient to characterize ecosystem responses. This study capitalized on a long-term reciprocal soil transplant experiment to examine the response of dryland soils to climate change. The two transplant sites were separated by 500 m of elevation on the same mountain slope in eastern Washington state, USA, and had similar plant species and soil types. We resampled the original 1994 soil transplants and controls, measuring CO2 production, temperature response, enzyme activity, and bacterial community structure after 17 years. Over a laboratory incubation of 100 days, reciprocally transplanted soils respired roughly equal cumulative amounts of carbon as non-transplanted controls from the same site. Soils transplanted from the hot, dry, lower site to the cooler and wetter (difference of -5°C monthly maximum air temperature, +50 mm yr-1 precipitation) upper site exhibited almost no respiratory response to temperature (Q10 of 1.1), but soils originally from the upper, cooler site had generally higher respiration rates. The bacterial community structure of transplants did not differ significantly from that of untransplanted controls, however. Slight differences in local climate between the upper and lower Rattlesnake locations, simulated with environmental control chambers during the incubation, thus prompted significant differences in microbial activity, with no observed change to bacterial structure. These results support the idea that environmental shifts can influence soil C through metabolic changes, and suggest that microbial populations responsible for soil heterotrophic respiration may be constrained in surprising ways, even as shorter- and

  1. Soil Respiration and Bacterial Structure and Function after 17 Years of a Reciprocal Soil Transplant Experiment.

    PubMed

    Bond-Lamberty, Ben; Bolton, Harvey; Fansler, Sarah; Heredia-Langner, Alejandro; Liu, Chongxuan; McCue, Lee Ann; Smith, Jeffrey; Bailey, Vanessa

    2016-01-01

    The effects of climate change on soil organic matter-its structure, microbial community, carbon storage, and respiration response-remain uncertain and widely debated. In addition, the effects of climate changes on ecosystem structure and function are often modulated or delayed, meaning that short-term experiments are not sufficient to characterize ecosystem responses. This study capitalized on a long-term reciprocal soil transplant experiment to examine the response of dryland soils to climate change. The two transplant sites were separated by 500 m of elevation on the same mountain slope in eastern Washington state, USA, and had similar plant species and soil types. We resampled the original 1994 soil transplants and controls, measuring CO2 production, temperature response, enzyme activity, and bacterial community structure after 17 years. Over a laboratory incubation of 100 days, reciprocally transplanted soils respired roughly equal cumulative amounts of carbon as non-transplanted controls from the same site. Soils transplanted from the hot, dry, lower site to the cooler and wetter (difference of -5°C monthly maximum air temperature, +50 mm yr-1 precipitation) upper site exhibited almost no respiratory response to temperature (Q10 of 1.1), but soils originally from the upper, cooler site had generally higher respiration rates. The bacterial community structure of transplants did not differ significantly from that of untransplanted controls, however. Slight differences in local climate between the upper and lower Rattlesnake locations, simulated with environmental control chambers during the incubation, thus prompted significant differences in microbial activity, with no observed change to bacterial structure. These results support the idea that environmental shifts can influence soil C through metabolic changes, and suggest that microbial populations responsible for soil heterotrophic respiration may be constrained in surprising ways, even as shorter- and

  2. Soil Respiration and Bacterial Structure and Function after 17 Years of a Reciprocal Soil Transplant Experiment.

    PubMed

    Bond-Lamberty, Ben; Bolton, Harvey; Fansler, Sarah; Heredia-Langner, Alejandro; Liu, Chongxuan; McCue, Lee Ann; Smith, Jeffrey; Bailey, Vanessa

    2016-01-01

    The effects of climate change on soil organic matter-its structure, microbial community, carbon storage, and respiration response-remain uncertain and widely debated. In addition, the effects of climate changes on ecosystem structure and function are often modulated or delayed, meaning that short-term experiments are not sufficient to characterize ecosystem responses. This study capitalized on a long-term reciprocal soil transplant experiment to examine the response of dryland soils to climate change. The two transplant sites were separated by 500 m of elevation on the same mountain slope in eastern Washington state, USA, and had similar plant species and soil types. We resampled the original 1994 soil transplants and controls, measuring CO2 production, temperature response, enzyme activity, and bacterial community structure after 17 years. Over a laboratory incubation of 100 days, reciprocally transplanted soils respired roughly equal cumulative amounts of carbon as non-transplanted controls from the same site. Soils transplanted from the hot, dry, lower site to the cooler and wetter (difference of -5°C monthly maximum air temperature, +50 mm yr-1 precipitation) upper site exhibited almost no respiratory response to temperature (Q10 of 1.1), but soils originally from the upper, cooler site had generally higher respiration rates. The bacterial community structure of transplants did not differ significantly from that of untransplanted controls, however. Slight differences in local climate between the upper and lower Rattlesnake locations, simulated with environmental control chambers during the incubation, thus prompted significant differences in microbial activity, with no observed change to bacterial structure. These results support the idea that environmental shifts can influence soil C through metabolic changes, and suggest that microbial populations responsible for soil heterotrophic respiration may be constrained in surprising ways, even as shorter- and

  3. Soil microbial respiration (CO2) of natural and anthropogenically-transformed ecosystems in Moscow region, Russia

    NASA Astrophysics Data System (ADS)

    Ivashchenko, Kristina; Ananyeva, Nadezhda; Rogovaya, Sofia; Vasenev, Viacheslav

    2016-04-01

    The CO2 concentration in modern atmosphere is increasing and one of the most reasons of it is land use changing. It is related not only with soil plowing, but also with growing urbanization and, thereby, forming the urban ecosystems. Such conversion of soil cover might be affected by efflux CO2 from soil into atmosphere. The soil CO2 efflux mainly supplies by soil microorganisms respiration (contribution around 70-90%) and plant roots respiration. Soil microbial respiration (MR) is determined in the field (in situ) and laboratory (in vitro) conditions. The measurement of soil MR in situ is labour-consuming, and for district, region and country areas it is difficult carried. We suggest to define the MR of the upper highest active 10 cm mineral soil layer (in vitro) followed by the accounting of area for different ecosystems in large region of Russia. Soils were sampled (autumn, 2011) in natural (forest, meadow) and anthropogenically-transformed (arable, urban) ecosystems of Sergiev-Posad, Taldom, Voskresenk, Shatura, Serpukhov and Serbryanye Prudy districts in Moscow region. In soil samples (total 156) the soil MR (24 h, 22°C, 60% WHC) were measured after preincubation procedure (7 d., 22°C, 55% WHC). The soil MR ranged from 0.13 (urban) to 5.41 μg CO2-C g-1 h-1 (meadow), the difference between these values was 42 times. Then, the soil MR values (per unit soil weight) were calculated per unit soil area (1 m2), the layer thickness of which was 0.1 m (soil volume weight was equaled 1 g cm-3). The high MR values were noted for forests soil (832-1410 g CO2-C m-2 yr-1) of studied districts, and the low MR values were for arable and urban soils (by 1.6-3.2 and 1.3-2.7 times less compared to forests, respectively). The MR rate of urban soil in Voskresenk district was comparable to that of corresponding meadows and it was even higher (in average by 2.3 times) in Serpukhov district. The soil MR rate of studied cities was higher by 20%, than in corresponding arable soils

  4. Arbuscular mycorrhizal fungi regulate soil respiration and its response to precipitation change in a semiarid steppe.

    PubMed

    Zhang, Bingwei; Li, Shan; Chen, Shiping; Ren, Tingting; Yang, Zhiqiang; Zhao, Hanlin; Liang, Yu; Han, Xingguo

    2016-01-01

    Arbuscular mycorrhizal fungi (AMF) are critical links in plant-soil continuum and play a critical role in soil carbon cycles. Soil respiration, one of the largest carbon fluxes in global carbon cycle, is sensitive to precipitation change in semiarid ecosystems. In this study, a field experiment with fungicide application and water addition was conducted during 2010-2013 in a semiarid steppe in Inner Mongolia, China, and soil respiration was continuously measured to investigate the influences of AMF on soil respiration under different precipitation regimes. Results showed that soil respiration was promoted by water addition treatment especially during drought seasons, which induced a nonlinear response of soil respiration to precipitation change. Fungicide application suppressed AMF root colonization without impacts on soil microbes. AMF suppression treatment accelerated soil respiration with 2.7, 28.5 and 37.6 g C m(-2) across three seasons, which were mainly caused by the enhanced heterotrophic component. A steeper response of soil respiration rate to precipitation was found under fungicide application treatments, suggesting a greater dampening effect of AMF on soil carbon release as water availability increased. Our study highlighted the importance of AMF on soil carbon stabilization and sequestration in semiarid steppe ecosystems especially during wet seasons. PMID:26818214

  5. Arbuscular mycorrhizal fungi regulate soil respiration and its response to precipitation change in a semiarid steppe

    PubMed Central

    Zhang, Bingwei; Li, Shan; Chen, Shiping; Ren, Tingting; Yang, Zhiqiang; Zhao, Hanlin; Liang, Yu; Han, Xingguo

    2016-01-01

    Arbuscular mycorrhizal fungi (AMF) are critical links in plant–soil continuum and play a critical role in soil carbon cycles. Soil respiration, one of the largest carbon fluxes in global carbon cycle, is sensitive to precipitation change in semiarid ecosystems. In this study, a field experiment with fungicide application and water addition was conducted during 2010–2013 in a semiarid steppe in Inner Mongolia, China, and soil respiration was continuously measured to investigate the influences of AMF on soil respiration under different precipitation regimes. Results showed that soil respiration was promoted by water addition treatment especially during drought seasons, which induced a nonlinear response of soil respiration to precipitation change. Fungicide application suppressed AMF root colonization without impacts on soil microbes. AMF suppression treatment accelerated soil respiration with 2.7, 28.5 and 37.6 g C m−2 across three seasons, which were mainly caused by the enhanced heterotrophic component. A steeper response of soil respiration rate to precipitation was found under fungicide application treatments, suggesting a greater dampening effect of AMF on soil carbon release as water availability increased. Our study highlighted the importance of AMF on soil carbon stabilization and sequestration in semiarid steppe ecosystems especially during wet seasons. PMID:26818214

  6. Arbuscular mycorrhizal fungi regulate soil respiration and its response to precipitation change in a semiarid steppe

    NASA Astrophysics Data System (ADS)

    Zhang, Bingwei; Li, Shan; Chen, Shiping; Ren, Tingting; Yang, Zhiqiang; Zhao, Hanlin; Liang, Yu; Han, Xingguo

    2016-01-01

    Arbuscular mycorrhizal fungi (AMF) are critical links in plant–soil continuum and play a critical role in soil carbon cycles. Soil respiration, one of the largest carbon fluxes in global carbon cycle, is sensitive to precipitation change in semiarid ecosystems. In this study, a field experiment with fungicide application and water addition was conducted during 2010–2013 in a semiarid steppe in Inner Mongolia, China, and soil respiration was continuously measured to investigate the influences of AMF on soil respiration under different precipitation regimes. Results showed that soil respiration was promoted by water addition treatment especially during drought seasons, which induced a nonlinear response of soil respiration to precipitation change. Fungicide application suppressed AMF root colonization without impacts on soil microbes. AMF suppression treatment accelerated soil respiration with 2.7, 28.5 and 37.6 g C m‑2 across three seasons, which were mainly caused by the enhanced heterotrophic component. A steeper response of soil respiration rate to precipitation was found under fungicide application treatments, suggesting a greater dampening effect of AMF on soil carbon release as water availability increased. Our study highlighted the importance of AMF on soil carbon stabilization and sequestration in semiarid steppe ecosystems especially during wet seasons.

  7. Soil microbial respiration from various microhabitats in Arctic landscape: impact of soil type, environmental conditions and soil age

    NASA Astrophysics Data System (ADS)

    Biasi, Christina; Jokinen, Simo; Marushchak, Maija; Trubnikova, Tatiana; Hämäläinen, Kai; Oinonen, Markku; Martikainen, Pertti

    2014-05-01

    Soil respiration is the second largest C flux between atmosphere and terrestrial ecosystems after gross primary production. Carbon dioxide released from soils is thus a major contributor to the atmospheric CO2 concentration. Despite the global importance, soil respiration and its components (heterotrophic and autotrophic respiration) remain poorly understood and not well constrained fluxes of the terrestrial C cycle. This is particularly true for the Arctic, where huge amounts of the Earth's soil carbon is stored. Here, we report on heterotrophic soil respiration rates from various Arctic tundra microhabitats measured in situ. The study site was Seida (67°07'N, 62°57'E, 100 m a.s.l.) which is characterized by typical sub-arctic permafrost landscape which comprises raised, vegetated permafrost peat plateaus, interspersed with spots of bare peat surfaces (peat circles), and upland mineral soils. We used isotope partitioning approach based on differences in natural abundance of 14C between soil and plants to separate sources of soil-respired CO2. In addition, the tradition trenching approach was employed. Complementary laboratory incubations with homogenized soil were conducted to assess primary decomposability of the soils and to identify age of the CO2 released and thus get more information on the nature of the sources of respiration. The major aim was to link SMR rates with of soil type, land cover class, soil physic-chemical properties (e.g. water content), soil C stocks and age of soil. Results show that, despite profound differences in soil characteristics and primary decomposability of organic matter, surface CO2 fluxes derived from soil microbial respiration rates were rather similar between microhabitats. The only factor which influenced, at least to some extent, the respiration rates was total soil C (and N) stocks in surface soils. There was some evidence for reduced soil-related CO2 emissions from peatlands, though results were not consistent between the

  8. Reduced temperature sensitivity of soil respiration after a 17-year climate change experiment

    NASA Astrophysics Data System (ADS)

    Bond-Lamberty, B. P.; Bailey, V. L.; Fansler, S.; Liu, C.; Smith, J. L.; Bolton, H.

    2012-12-01

    In 1994, a reciprocal soil transplant experiment was initiated between two elevations (310 m, warmer and drier, and 844 m, cooler and wetter) on Rattlesnake Mountain in southeastern Washington, USA, testing whether the microbial and biochemical dynamics that developed under cool, moist conditions would be destabilized under hot, dry conditions. In March 2012 we resampled the original transplanted soils to study longer-term changes in microbial community composition, soil C and N dynamics, and soil physical structure. These resampled cores were randomly assigned to climate-control chambers simulating the lower or upper site climates. We measured respiration throughout a 100-day incubation, coupled with biogeochemical analyses, to examine how these soils had responded to environmental changes over 17 years. Temperature and soil moisture were the primary drivers of CO2 evolution, but transplant source and destination both exerted significant effects. Most strikingly, respiration from cores originally from the hotter, low-elevation site that spent 17 years at the upper site exhibited almost no temperature sensitivity (Q10=1.07, 13-33 °C). Cores from the upper site had more carbon (~1.1% versus 0.8%), but equivalent C:N ratios, while soils incubated in the 'upper' chamber had greater N-acetylglucosaminidase and β-glucosidase potentials. Tomographic reconstructions revealed that porosity, moisture content, grain size distribution, and organic C were highly heterogeneous, consistent with the observed macro-scale variability. These results suggest that the upper-site soils were more resilient to the 1994 transplant, but that there is a significantly altered microbial community in the transplanted soils, particularly the lower-to-upper cores, that has not recovered almost two decades after the original experiment. This raises more general questions of how current climate change will affect soil resistance to future perturbations, and how confidently we can model this

  9. Soil Respiration Responses to Variation in Temperature Treatment and Vegetation Type

    NASA Astrophysics Data System (ADS)

    Liu, S.; Pavao-zuckerman, M.

    2013-12-01

    Complex linkages exist between terrestrial vegetation, soil moisture, soil organic matter (SOM), local climate, and soil microorganisms. Thus, large-scale changes in vegetation, such as the woody plant encroachment observed in many historically semiarid and arid grasslands worldwide, could potentially alter the flux of carbon from soil reserves to the atmosphere. Mathematical models that attempt to project the long-term impact of vegetative shifts on soil fluxes largely rely on assumptions such as first-order donor control rather than incorporate the biological aspects of soil respiration such as microbial activity. To examine the impact of vegetation type on soil physicochemical properties and soil microbial respiration and provide experimental data to refine existing predictive models, we compared soil (ground basalt from northern Arizona) in mesocosms established with no vegetation, velvet mesquites (Prosopis velutina; woody shrub), or sideoats gramas (Bouteloua curtipendula; grass) for 2 years, The temperature sensitivity of soil respiration was examined by incubating soil (0-10 and 10-30 cm depth fractions) from each vegetation treatment at 10, 20, 30, and 40 °C for 24 hours. Vegetated soils contained more SOM (~0.1% for mesquite and grass mesocosms) than non-vegetated soils (~0.02%). Respiration rates were generally highest from grass-established soils, intermediate from mesquite-established soils, and lowest from non-vegetated soils. Respiration rates of samples incubated without the addition of substrate peaked at approximately 30 °C, whereas respiration rates of samples incubated with dextrose were highest at 40 °C. Further, the respiration assays suggest that while respiration rates are overall higher in grass-established soils, mesquite-established soils are more temperature sensitive which may have significant implications in the context of global warming and current fire management practices.

  10. Effects of a clear-cut harvest on soil respiration in a jack pine - Lichen woodland

    USGS Publications Warehouse

    Striegl, R.G.; Wickland, K.P.

    1998-01-01

    Quantification of the components of ecosystem respiration is essential to understanding carbon (C) cycling of natural and disturbed landscapes. Soil respiration, which includes autotrophic and heterotrophic respiration from throughout the soil profile, is the second largest flux in the global carbon cycle. We measured soil respiration (soil CO2 emission) at an undisturbed mature jack pine (Pinus banksiana Lamb.) stand in Saskatchewan (old jack pine, OJP), and at a formerly continuous portion of the stand that was clear-cut during the previous winter (clear-cut, CC). Tree harvesting reduced soil CO2 emission from ???22.5 to ???9.1 mol CO2??m2 for the 1994 growing season. OJP was a small net sink of atmospheric CO2, while CC was a net source of CO2. Winter emissions were similar at both sites. Reduction of soil respiration was attributed to disruption of the soil surface and to the death of tree roots. Flux simulations for CC and OJP identify 40% of CO2 emission at the undisturbed OJP site as near-surface respiration, 25% as deep-soil respiration, and 35% as tree-root respiration. The near-surface component was larger than the estimated annual C input to soil, suggesting fast C turnover and no net C accumulation in these boreal uplands in 1994.

  11. [Contribution of litter to soil respiration under different land-use types in Sanjiang Plain].

    PubMed

    Wang, Li-Li; Song, Chang-Chun; Guo, Yue-Dong; Liu, De-Yan; Yang, Gui-Sheng

    2009-11-01

    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.

  12. Partitioning soil respiration: examining the artifacts of the trenching method.

    NASA Astrophysics Data System (ADS)

    Savage, K. E.; Davidson, E. A.; Finzi, A.; Giasson, M. A.; Wehr, R. A.

    2014-12-01

    Soil respiration (Rs) is a combination of autotrophic (Ra) and heterotrophic respiration (Rh). Several methods have been developed to tease out the components of Rs, such as isotopic analyses, and removing Ra input through tree girdling and root exclusion experiments. Trenching involves severing the rooting system surrounding a plot to remove the Ra component within the plot. This method has some potential limitations. Reduced water uptake in trenched plots could change soil water content, which is one of the environmental controllers of Rs in many ecosystems. Eliminating root inputs could reduce heterotrophic decomposition of SOM via lack of priming. On the other hand, the severed dead roots may temporarily increase available carbon substrate for Rh. At the Harvard Forest, MA, we used the trenching method to partition Rs into its components Ra and Rh. Pre-trenched Rs was measured from spring to fall of 2012. In late fall of 2012, a trench was excavated to 1m depth around a 5x5m area, severing all roots. Plastic tarp was placed along the trench walls and then backfilled. Four automated Rs chambers were placed in the trenched plot and four in an un-trenched plot. Respiration was measured hourly for each chamber along with soil temperature and moisture from spring through fall of 2013 and 2014. Eighty root decomposition bags were placed in the organic soil horizon of the trenched (40) and un-trenched (40) plots at the time of trenching in 2012 and measured in 2013 and 2014. These data are being used to estimate the size and duration of any artifact due to root death. As expected, Rs was lower in the trenched plot (Rh only) than in the un-trenched plot (Rh + Ra) in 2013, but the reverse was unexpectedly observed during a period of low precipitation in 2014. High rates of ET combined with below-average precipitation dried the un-trenched plot to a point where Rh was inhibited, whereas less ET allowed the un-trenched plots to remain measurably wetter.

  13. Invasion of a semi-arid shrubland by annual grasses increases autotrophic and heterotrophic soil respiration rates due to altered soil moisture and temperature patterns

    NASA Astrophysics Data System (ADS)

    Mauritz, M.; Hale, I.; Lipson, D.

    2010-12-01

    Shrub <-> grassland conversions are a globally occurring phenomenon altering habitat structure, quality and nutrient cycling. Grasses and shrubs differ in their above and belowground biomass allocation, root architecture, phenology, litter quality and quantity. Conversion affects soil microbial communities, soil moisture and temperature and carbon (C) allocation patterns. However, the effect of conversion on C storage is regionally variable and there is no consistent direction of change. In Southern California invasion by annual grasses is a major threat to native shrub communities and it has been proposed that grass invasion increases NPP and ecosystem C storage (Wolkovich et al, 2009). In order to better understand how this shrub <-> grassland conversion changes ecosystem C storage it is important to understand the partitioning of soil respiration into autotrophic and heterotrophic components. Respiration was measured in plots under shrubs and grasses from February when it was cold and wet to July when it was hot and dry, capturing seasonal transitions in temperature and water availability. Roots were excluded under shrubs and grasses with root exclusion cores to quantify heterotrophic respiration. Using total soil respiration (Rt) = autotrophic respiration (root) (Ra)+ heterotrophic respiration (microbial) (Rh) the components contributing to total soil respiration can be evaluated. Respiration, soil moisture and temperature were measured daily at four hour intervals using Licor 8100 automated chamber measurements. Throughout the measurement period, Rt under grasses exceeded Rt under shrubs. Higher Rt levels under grasses were mainly due to higher Ra in grasses rather than changes in Rh. On average grass Ra was almost double shrub Ra. Higher grass respiration levels are partially explained by differences in soil moisture and temperature between shrubs and grasses. Respiration rates responded similarly to seasonal transitions regardless of treatment although Ra

  14. Effect of organic matter and roots in soil respiration in a Mediterranean riparian areas in Central Spain

    NASA Astrophysics Data System (ADS)

    Gonzalez-Garrido, Laura; Delgado, Juan Antonio; Martinez, Teodora

    2010-05-01

    Soil respiration is one of the largest carbon flux components within terrestrial ecosystems, and small changes in the magnitude of soil respiration could have a large effect on the concentration of CO2 in the atmosphere. The main objective is evaluating the factors controlling soil respiration on the global carbon cycle in riparian areas of Henares River. We evaluated total soil respiration as it was affected by soil temperature, soil moisture, root respiration and organic matter in four areas differing in vegetation cover. We specifically assessed the contribution of soil organic matter and fine root biomass (≤1 mm.) in soil carbon dioxide flux. The study area is located on the riverbanks of Henares River where it passes through the municipal term of Alcala de Henares (Madrid) in Central Spain. Measurements were performed in spring and autumn of 2009. The study was conducted on four different types of riparian vegetation: natural Mediterranean riparian forest, reforestation of 1994, reforestation of 1999 and riparian grassland without trees. In each area of study 3, 25x25 m, plots were delimited and within each plot three sampling units of 50x50 cm were selected at random. The temperature of the ground was taken during the measures from respiration using a Multi-thermometer (-50°C - +300°C) at 5 cm depth. The moisture content of the ground was measured at 5 cm of depth with a HH2 Moisture meter (Delta Devices, Cambridge, UK). The measures of respiration of the ground were realised in field by means of LCI portable (LC pro ADC Bioscientific, Ltd. UK) connected to a ground respiration camera. We introduced the camera 3 cm into the soil just after eliminating the vegetation grass of the surface of measurement cutting carefully the aerial part, without damaging the roots. Soil CO2 flux measurements were registered after stabilization. Immediately after CO2 measurements, we obtained soil samples by means of a drill of 2.18 cm of diameter taking samples to 10 cm and

  15. Seasonal Variation in Soil Microbial Biomass, Bacterial Community Composition and Extracellular Enzyme Activity in Relation to Soil Respiration in a Northern Great Plains Grassland

    NASA Astrophysics Data System (ADS)

    Wilton, E.; Flanagan, L. B.

    2014-12-01

    Soil respiration rate is affected by seasonal changes in temperature and moisture, but is this a direct effect on soil metabolism or an indirect effect caused by changes in microbial biomass, bacterial community composition and substrate availability? In order to address this question, we compared continuous measurements of soil and plant CO2 exchange made with an automatic chamber system to analyses conducted on replicate soil samples collected on four dates during June-August. Microbial biomass was estimated from substrate-induced respiration rate, bacterial community composition was determined by 16S rRNA amplicon pyrosequencing, and β-1,4-N-acetylglucosaminidase (NAGase) and phenol oxidase enzyme activities were assayed fluorometrically or by absorbance measurements, respectively. Soil microbial biomass declined from June to August in strong correlation with a progressive decline in soil moisture during this time period. Soil bacterial species richness and alpha diversity showed no significant seasonal change. However, bacterial community composition showed a progressive shift over time as measured by Bray-Curtis dissimilarity. In particular, the change in community composition was associated with increasing relative abundance in the alpha and delta classes, and declining abundance of the beta and gamma classes of the Proteobacteria phylum during June-August. NAGase showed a progressive seasonal decline in potential activity that was correlated with microbial biomass and seasonal changes in soil moisture. In contrast, phenol oxidase showed highest potential activity in mid-July near the time of peak soil respiration and ecosystem photosynthesis, which may represent a time of high input of carbon exudates into the soil from plant roots. This input of exudates may stimulate the activity of phenol oxidase, a lignolytic enzyme involved in the breakdown of soil organic matter. These analyses indicated that seasonal change in soil respiration is a complex

  16. Forest soil respiration rate and delta13C is regulated by recent above ground weather conditions.

    PubMed

    Ekblad, Alf; Boström, Björn; Holm, Anders; Comstedt, Daniel

    2005-03-01

    Soil respiration, a key component of the global carbon cycle, is a major source of uncertainty when estimating terrestrial carbon budgets at ecosystem and higher levels. Rates of soil and root respiration are assumed to be dependent on soil temperature and soil moisture yet these factors often barely explain half the seasonal variation in soil respiration. We here found that soil moisture (range 16.5-27.6% of dry weight) and soil temperature (range 8-17.5 degrees C) together explained 55% of the variance (cross-validated explained variance; Q2) in soil respiration rate (range 1.0-3.4 micromol C m(-2) s(-1)) in a Norway spruce (Picea abies) forest. We hypothesised that this was due to that the two components of soil respiration, root respiration and decomposition, are governed by different factors. We therefore applied PLS (partial least squares regression) multivariate modelling in which we, together with below ground temperature and soil moisture, used the recent above ground air temperature and air humidity (vapour pressure deficit, VPD) conditions as x-variables. We found that air temperature and VPD data collected 1-4 days before respiration measurements explained 86% of the seasonal variation in the rate of soil respiration. The addition of soil moisture and soil temperature to the PLS-models increased the Q2 to 93%. delta13C analysis of soil respiration supported the hypotheses that there was a fast flux of photosynthates to root respiration and a dependence on recent above ground weather conditions. Taken together, our results suggest that shoot activities the preceding 1-6 days influence, to a large degree, the rate of root and soil respiration. We propose this above ground influence on soil respiration to be proportionally largest in the middle of the growing season and in situations when there is large day-to-day shifts in the above ground weather conditions. During such conditions soil temperature may not exert the major control on root respiration. PMID

  17. Continuous soil respiration measurements and data quality control using the FD chamber technique

    NASA Astrophysics Data System (ADS)

    Nickerson, N.; Creelman, C.

    2015-12-01

    Continuous soil respiration data sets have become increasingly common with the availability of automated soil respiration measurement systems. These continuous data have revealed a great deal about short time-scale temporal responses to environmental drivers such as soil temperature and moisture content, as well as linkages between above- and below-ground processes. Forced Diffusion (FD) is a novel method for continuous measurement of soil respiration (Risk et al., 2011). The FD technique is functionally similar to dynamic steady-state chamber systems but uses a diffusive membrane to regulate the flow of gases rather than a pump. Measurement of soil respiration using this diffusive regulation approach has several benefits including reduced power consumption and the ability to function in harsh environments including under snow pack. Here we present a continuous multi-month forest soil respiration data set collected using the FD technique in Nova Scotia, Canada. Data spanning the autumn (August-December) will be presented, which includes both autotrophic senescence as well as the Atlantic hurricane season. Temporal dynamics associated with long-term and short-term temperature variability are evident in the data set, as well as multiple respiration pulse events associated with heavy rainfalls during autumnal storms. We will also demonstrate the application of a straightforward algorithm used for quality control (QC) of continuous soil respiration data. The QC technique uses a combination of predictive modeling and comparison of probability density functions (Lavoie et al., 2015) that result in robust identification of outliers in continuous soil respiration data sets.

  18. Mathematical modelling of soil respiration and carbon accumulation dynamics in soils of CELSS

    NASA Astrophysics Data System (ADS)

    Bartsev, Sergey; Pochekutov, Alexey

    Long-term human abidance out of Earth is possible under conditions providing living environ-ment similar to natural with respect to valuable parameters. In fact, it is necessary to build a little part of Earth biosphere. In the case of lunar or martial base, due to absence of a mass limitation, we can consider higher plant cultivation not only on soilless substrates, but also on soils similar to natural ones. Mathematical modelling of carbon cycle in CELSS including soil requires considering carbon accumulation in soil organic matter (SOM) and carbon emission from SOM into the atmosphere due to soil respiration. A mathematical model of soil respiration and carbon transfer in soil reservoirs is based on the suggestion that the biomass destruction and transformation of soil organic matter are performed by living organisms is proposed. As well as in all organisms, an optimal value of temperature, moisture and other environment parameters at which life activity is maximal, and a tolerable range of these parameters out of which their life activity ceases, are inherent in soil microorganisms. Therefore the coefficients of carbon transformation rates in soil have to be specified by multiplications of an unimodal func-tion of temperature and an unimodal function of moisture. These functions have maximums at the optimal value of temperature or moisture and are equal to zero at the boundaries of tolerable range. The mathematical model presents a systems of kinetic differential equations. The model allows to calculate the dynamics of soil accumulation, the dynamics of SOM in the soil reservoirs and the dynamics of soil respiration, for specified temperature ans moisture parameters.

  19. Seasonal and annual changes in soil respiration in relation to soil temperature, water potential and trenching.

    PubMed

    Lavigne, M B; Foster, R J; Goodine, G

    2004-04-01

    Soil respiration (rs), soil temperature (Ts) and volumetric soil water content were measured in a balsam fir (Abies balsamea (L.) Mill.) ecosystem from 1998 to 2001. Seasonal variation in root and microbial respiration, and covariation in abiotic factors confounded interpretation of the effects of Ts and soil water potential (Psis) on rs. To minimize the confounding effect of temperature, we analyzed the effect of Psis on rs during the summers of 1998-2000 when changes in Ts were slight. Soil respiration declined 25-50% in response to modest water stress (minimum Psis of -0.6 to -0.2 MPa), and between years, there was substantial variation in the relationship between rs and Psis. In the summer of 2000, 2-m2 plots were subjected to drought for 1 month and other plots were irrigated. The relationship between summertime rs and Psis in the experimental plots was similar to that estimated from the survey data obtained during the same summer. In late spring and early autumn of 2001, 2-m2 trenched and untrenched plots were subjected to drought or exposed to rainfall. It was dry in the early autumn and there was severe soil drying (Psis of -10 MPa in untrenched plots and -2 MPa in trenched plots). In spring, rs in untrenched plots responded more to modest water stress than rs in trenched plots, indicating that root respiration is more sensitive than microbial respiration to water stress at this time of year. The response to abiotic factors differed significantly between spring and autumn in untrenched plots but not in trenched plots, indicating that root activity was greater in early autumn than in late spring, and that roots acclimated to the sustained, severe water stress experienced before and during the autumn. PMID:14757581

  20. Strong resilience of soil respiration components to drought-induced die-off resulting in forest secondary succession.

    PubMed

    Barba, Josep; Curiel Yuste, Jorge; Poyatos, Rafael; Janssens, Ivan A; Lloret, Francisco

    2016-09-01

    How forests cope with drought-induced perturbations and how the dependence of soil respiration on environmental and biological drivers is affected in a warming and drying context are becoming key questions. The aims of this study were to determine whether drought-induced die-off and forest succession were reflected in soil respiration and its components and to determine the influence of climate on the soil respiration components. We used the mesh exclusion method to study seasonal variations in soil respiration (R S) and its components: heterotrophic (R H) and autotrophic (R A) [further split into fine root (R R) and mycorrhizal respiration (R M)] in a mixed Mediterranean forest where Scots pine (Pinus sylvestris L.) is undergoing a drought-induced die-off and is being replaced by holm oak (Quercus ilex L.). Drought-induced pine die-off was not reflected in R S nor in its components, which denotes a high functional resilience of the plant and soil system to pine die-off. However, the succession from Scots pine to holm oak resulted in a reduction of R H and thus in an important decrease of total respiration (R S was 36 % lower in holm oaks than in non-defoliated pines). Furthermore, R S and all its components were strongly regulated by soil water content-and-temperature interaction. Since Scots pine die-off and Quercus species colonization seems to be widely occurring at the driest limit of the Scots pine distribution, the functional resilience of the soil system over die-off and the decrease of R S from Scots pine to holm oak could have direct consequences for the C balance of these ecosystems. PMID:26879544

  1. Strong resilience of soil respiration components to drought-induced die-off resulting in forest secondary succession.

    PubMed

    Barba, Josep; Curiel Yuste, Jorge; Poyatos, Rafael; Janssens, Ivan A; Lloret, Francisco

    2016-09-01

    How forests cope with drought-induced perturbations and how the dependence of soil respiration on environmental and biological drivers is affected in a warming and drying context are becoming key questions. The aims of this study were to determine whether drought-induced die-off and forest succession were reflected in soil respiration and its components and to determine the influence of climate on the soil respiration components. We used the mesh exclusion method to study seasonal variations in soil respiration (R S) and its components: heterotrophic (R H) and autotrophic (R A) [further split into fine root (R R) and mycorrhizal respiration (R M)] in a mixed Mediterranean forest where Scots pine (Pinus sylvestris L.) is undergoing a drought-induced die-off and is being replaced by holm oak (Quercus ilex L.). Drought-induced pine die-off was not reflected in R S nor in its components, which denotes a high functional resilience of the plant and soil system to pine die-off. However, the succession from Scots pine to holm oak resulted in a reduction of R H and thus in an important decrease of total respiration (R S was 36 % lower in holm oaks than in non-defoliated pines). Furthermore, R S and all its components were strongly regulated by soil water content-and-temperature interaction. Since Scots pine die-off and Quercus species colonization seems to be widely occurring at the driest limit of the Scots pine distribution, the functional resilience of the soil system over die-off and the decrease of R S from Scots pine to holm oak could have direct consequences for the C balance of these ecosystems.

  2. Rapid decomposition of labile soil organic matter inputs obscures sensitivity of heterotrophic respiration to temperature: A model analysis.

    NASA Astrophysics Data System (ADS)

    Post, W. M.; Gu, L.; King, A. W.

    2003-12-01

    Labile carbon, although often a small fraction of soil organic matter (SOM), significantly affects heterotrophic respiration at short time scales because of its rapid decomposition. However, in the current literature, most soil respiration measurements are interpreted without simultaneous information on labile carbon pool dynamics. Sensitivity of soil respiration to temperature is routinely derived directly from field observations and such relationships have been used to extrapolate effects of global change (e.g. warming) on the carbon emission from SOM. Here we used a multi-pool SOM model to demonstrate the impacts of seasonal fluctuations in labile carbon pools. Labile carbon pool sizes varied widely in response to seasonal changes in representative plant material inputs and temperature even though the model was operating at an equilibrium state (in terms of annual means). Convolution of the dynamics of fast turnover carbon pools and temporal progression in temperature led to misrepresentation and misinterpretation of the heterotrophic respiration - temperature relationships estimated from bulk soil CO2 exchanges. Temperature sensitivity was overestimated when the variations of labile carbon pools and temperature were in phase and underestimated when they were out of phase. Furthermore, with normally used observation time windows (weeks to a year), temperature sensitivity was more likely to be underestimated. A distortion of temperature sensitivity (Q10) from 2 (actual, sensitive dependence on temperature) to nearly 1 (false, no dependence on temperature) was shown. Our analysis indicates that cautions must be taken when soil respiration - temperature relationships are evaluated based on bulk soil observations and that sensitivity of soil respiration to temperature estimated directly under field conditions should not be used to predict future carbon cycle climate feedbacks.

  3. [Effects of different tillage measures on upland soil respiration in Loess Plateau].

    PubMed

    Sun, Xiao-hua; Zhang, Ren-zhi; Cai, Li-qun; Chen, Qiang-qiang

    2009-09-01

    A field experiment was conducted in Lijiabu Town of Dingxi City, Gansu Province to study the soil respiration and its relations with the canopy temperature and soil moisture content in a rotation system with spring wheat and pea under effects of different tillage measures. Six treatments were installed, i.e., tillage with no straw- or plastic mulch (conventional tillage, T), tillage with straw mulch (TS), tillage with plastic mulch (TP), no-tillage (NT), no-tillage with straw mulch (NTS), and no-tillage with plastic mulch (NTP). During the growth periods of spring wheat and pea, soil respiration had different change patterns, with the peaks appeared at the early jointing, grain-filling, and maturing stages of spring wheat, and at the 5-leaf, silking, flowering and poding, in spring wheat field between treatments NTS and T, and the soil respiration rate was significantlyand maturing stages of pea. There was an obvious difference in the diurnal change of soil respiration lower in NTS than in T; while the soil respiration in pea field had less diurnal chan ge. Soil respiration rate had a significant linear relationship with the canopy temperature of both spring wheat andpea, the correlation coefficient being the highest at booting stage of spring wheat and at flowering and poding stage of pea, followed by at grain-filling stage of spring wheat and at branching stage of pea. There was also a significant parabola relationship between soil respiration rate and soil moisture content, the correlation coefficient being higher under conservation tillage than under conventional tillage, with the highest under NTS. The moisture content in 10-30 cm soil layer of spring wheat field and that in 5-10 cm soil layer of pea field had the greatest effects on soil respiration. Comparing with conventional tillage, all the five conservation tillage measures decreased soil respiration, with the best effects of no-tillage with straw mulch.

  4. Soil respiration and organic carbon dynamics with grassland conversions to woodlands in temperate china.

    PubMed

    Wang, Wei; Zeng, Wenjing; Chen, Weile; Zeng, Hui; Fang, Jingyun

    2013-01-01

    Soils are the largest terrestrial carbon store and soil respiration is the second-largest flux in ecosystem carbon cycling. Across China's temperate region, climatic changes and human activities have frequently caused the transformation of grasslands to woodlands. However, the effect of this transition on soil respiration and soil organic carbon (SOC) dynamics remains uncertain in this area. In this study, we measured in situ soil respiration and SOC storage over a two-year period (Jan. 2007-Dec. 2008) from five characteristic vegetation types in a forest-steppe ecotone of temperate China, including grassland (GR), shrubland (SH), as well as in evergreen coniferous (EC), deciduous coniferous (DC) and deciduous broadleaved forest (DB), to evaluate the changes of soil respiration and SOC storage with grassland conversions to diverse types of woodlands. Annual soil respiration increased by 3%, 6%, 14%, and 22% after the conversion from GR to EC, SH, DC, and DB, respectively. The variation in soil respiration among different vegetation types could be well explained by SOC and soil total nitrogen content. Despite higher soil respiration in woodlands, SOC storage and residence time increased in the upper 20 cm of soil. Our results suggest that the differences in soil environmental conditions, especially soil substrate availability, influenced the level of annual soil respiration produced by different vegetation types. Moreover, shifts from grassland to woody plant dominance resulted in increased SOC storage. Given the widespread increase in woody plant abundance caused by climate change and large-scale afforestation programs, the soils are expected to accumulate and store increased amounts of organic carbon in temperate areas of China. PMID:24058408

  5. Soil respiration and organic carbon dynamics with grassland conversions to woodlands in temperate china.

    PubMed

    Wang, Wei; Zeng, Wenjing; Chen, Weile; Zeng, Hui; Fang, Jingyun

    2013-01-01

    Soils are the largest terrestrial carbon store and soil respiration is the second-largest flux in ecosystem carbon cycling. Across China's temperate region, climatic changes and human activities have frequently caused the transformation of grasslands to woodlands. However, the effect of this transition on soil respiration and soil organic carbon (SOC) dynamics remains uncertain in this area. In this study, we measured in situ soil respiration and SOC storage over a two-year period (Jan. 2007-Dec. 2008) from five characteristic vegetation types in a forest-steppe ecotone of temperate China, including grassland (GR), shrubland (SH), as well as in evergreen coniferous (EC), deciduous coniferous (DC) and deciduous broadleaved forest (DB), to evaluate the changes of soil respiration and SOC storage with grassland conversions to diverse types of woodlands. Annual soil respiration increased by 3%, 6%, 14%, and 22% after the conversion from GR to EC, SH, DC, and DB, respectively. The variation in soil respiration among different vegetation types could be well explained by SOC and soil total nitrogen content. Despite higher soil respiration in woodlands, SOC storage and residence time increased in the upper 20 cm of soil. Our results suggest that the differences in soil environmental conditions, especially soil substrate availability, influenced the level of annual soil respiration produced by different vegetation types. Moreover, shifts from grassland to woody plant dominance resulted in increased SOC storage. Given the widespread increase in woody plant abundance caused by climate change and large-scale afforestation programs, the soils are expected to accumulate and store increased amounts of organic carbon in temperate areas of China.

  6. Soil respiration in the cold desert environment of the Colorado Plateau (USA): Abiotic regulators and thresholds

    USGS Publications Warehouse

    Fernandez, D.P.; Neff, J.C.; Belnap, J.; Reynolds, R.L.

    2006-01-01

    Decomposition is central to understanding ecosystem carbon exchange and nutrient-release processes. Unlike mesic ecosystems, which have been extensively studied, xeric landscapes have received little attention; as a result, abiotic soil-respiration regulatory processes are poorly understood in xeric environments. To provide a more complete and quantitative understanding about how abiotic factors influence soil respiration in xeric ecosystems, we conducted soil- respiration and decomposition-cloth measurements in the cold desert of southeast Utah. Our study evaluated when and to what extent soil texture, moisture, temperature, organic carbon, and nitrogen influence soil respiration and examined whether the inverse-texture hypothesis applies to decomposition. Within our study site, the effect of texture on moisture, as described by the inverse texture hypothesis, was evident, but its effect on decomposition was not. Our results show temperature and moisture to be the dominant abiotic controls of soil respiration. Specifically, temporal offsets in temperature and moisture conditions appear to have a strong control on soil respiration, with the highest fluxes occurring in spring when temperature and moisture were favorable. These temporal offsets resulted in decomposition rates that were controlled by soil moisture and temperature thresholds. The highest fluxes of CO2 occurred when soil temperature was between 10 and 16??C and volumetric soil moisture was greater than 10%. Decomposition-cloth results, which integrate decomposition processes across several months, support the soil-respiration results and further illustrate the seasonal patterns of high respiration rates during spring and low rates during summer and fall. Results from this study suggest that the parameters used to predict soil respiration in mesic ecosystems likely do not apply in cold-desert environments. ?? Springer 2006.

  7. Soil heterotrophic respiration responses to meteorology, soil types and cropping systems in a temperate agricultural watershed.

    NASA Astrophysics Data System (ADS)

    Buysse, Pauline; Viaud, Valérie; Fléchard, Chris

    2015-04-01

    Within the context of Climate Change, a better understanding of soil organic matter dynamics is of considerable importance in agro-ecosystems, due to their large mitigation potential. This study aims at better understanding the process of soil heterotrophic respiration at the annual scale and at the watershed scale, with these temporal and spatial scales allowing an integration of the most important drivers: cropping systems and management, topography, soil types, soil organic carbon content and meteorological conditions. Twenty-four soil CO2 flux measurement sites - comprising three PVC collars each - were spread over the Naizin-Kervidy catchment (ORE AgrHys, 4.9 km², W. France) in March 2014. These sites were selected in order to represent most of the diversity in drainage classes, soil types and cropping systems. Soil CO2 flux measurements were performed about every ten to fifteen days at each site, starting from 20 March 2014, using the dynamic closed chamber system Li-COR 8100. Soil temperature and soil moisture content down to 5 cm depth were measured simultaneously. An empirical model taking the influence of meteorological drivers (soil temperature and soil water content) on soil CO2 fluxes was applied to each site and the different responses were analyzed with regard to site characteristics (topography, soil organic carbon content, soil microbial biomass, crop type, crop management,…) in order to determine the most important driving variables of soil heterotrophic respiration. The modeling objective is then to scale the fluxes measured at all sites up to the full watershed scale.

  8. [Effect of vegetation types on soil respiration characteristics on a smaller scale].

    PubMed

    Yan, Jun-Xia; Li, Hong-Jian; Tang, Yi; Zhang, Yi-Hui

    2009-11-01

    Soil respiration was measured from April 2005 to December 2007 using a LICOR-6400-09 chamber connecting a LiCor-6400 portable photosynthesis system at 3 sites with same elevation and soil texture but different vegetation types. The results indicated that seasonal trend of soil respiration showed a distinct temporal change with the higher values in summer and autumn months and the lower values in winter and spring. Annual means (March to December) of soil respiration for 3 the sampling sites were(3.58 +/- 2.50), (3.82 +/- 2.75) and (4.42 +/- 3.38) micromol x (m2 x s)(-1) (p > 0.05), respectively. Released annual amount (March to December) of CO2 efflux from 3 sites was from 854.9 to 1 297.2 g x (m2 x a)(-1) and the amount was no difference between sites and among years. The fitted exponential equations of soil respiration and soil temperature for 3 sites were all significant with the R2 from 0.61 to 0.81, and the Q10 and R10 calculated from fitted parameters of the equations ranged from 2.60 to 4.50, and from 1.70 to 3.02 micromol x (m2 x s)(-1). The relationships between soil respiration and soil water content were not significant for all 3 sites with a maximum R2 of the regression equations only 0.12 (p > 0.05). However, when the soil temperature was above 10 degrees C, the relationships between soil respiration and soil water content was significant (p < 0.05). Four combined regression equations including soil temperature and soil water content could be used to model relationships between soil respiration and both soil temperature and soil water content together, with the R2 most above 0.7, and maximum of 0.91. PMID:20063717

  9. Different soil respiration responses to litter manipulation in three subtropical successional forests

    PubMed Central

    Han, Tianfeng; Huang, Wenjuan; Liu, Juxiu; Zhou, Guoyi; Xiao, Yin

    2015-01-01

    Aboveground litter inputs have been greatly altered by human disturbances and climate change, which have important effects on soil respiration. However, the knowledge of how soil respiration responds to altered litter inputs is limited in tropical and subtropical forests. We conducted an aboveground litterfall manipulation experiment in three successional forests in the subtropics to examine the soil respiration responses to different litter inputs from January 2010 to July 2012. The soil respiration decreased by 35% in the litter exclusion treatments and increased by 77% in the doubled litter additions across all three forests. The reduction in soil respiration induced by the litter exclusion was greatest in the early successional forest, which may be related to a decrease in the soil moisture and shifts in the microbial community. The increase in soil respiration produced by the doubled litter addition was largest in the mature forest, which was most probably due to its relatively high quantity and quality of litterfall. Our results suggest that the effect of reduced litter inputs on the soil respiration lessened with forest succession but that the doubled litter inputs resulted in a stronger priming effect in the mature forest than in the other two forests. PMID:26656136

  10. Hydrologically transported dissolved organic carbon influences soil respiration in a tropical rainforest

    NASA Astrophysics Data System (ADS)

    Zhou, Wen-Jun; Lu, Hua-Zheng; Zhang, Yi-Ping; Sha, Li-Qing; Schaefer, Douglas Allen; Song, Qing-Hai; Deng, Yun; Deng, Xiao-Bao

    2016-10-01

    To better understand the effect of dissolved organic carbon (DOC) transported by hydrological processes (rainfall, throughfall, litter leachate, and surface soil water; 0-20 cm) on soil respiration in tropical rainforests, we detected the DOC flux in rainfall, throughfall, litter leachate, and surface soil water (0-20 cm), compared the seasonality of δ13CDOC in each hydrological process, and δ13C in leaves, litter, and surface soil, and analysed the throughfall, litter leachate, and surface soil water (0-20 cm) effect on soil respiration in a tropical rainforest in Xishuangbanna, south-west China. Results showed that the surface soil intercepted 94.4 ± 1.2 % of the annual litter leachate DOC flux and is a sink for DOC. The throughfall and litter leachate DOC fluxes amounted to 6.81 and 7.23 % of the net ecosystem exchange respectively, indicating that the DOC flux through hydrological processes is an important component of the carbon budget, and may be an important link between hydrological processes and soil respiration in a tropical rainforest. Even the variability in soil respiration is more dependent on the hydrologically transported water than DOC flux insignificantly, soil temperature, and soil-water content (at 0-20 cm). The difference in δ13C between the soil, soil water (at 0-20 cm), throughfall, and litter leachate indicated that DOC is transformed in the surface soil and decreased the sensitivity indices of soil respiration of DOC flux to water flux, which suggests that soil respiration is more sensitive to the DOC flux in hydrological processes, especially the soil-water DOC flux, than to soil temperature or soil moisture.

  11. Land cover heterogeneity and soil respiration in a west Greenland tundra landscape

    NASA Astrophysics Data System (ADS)

    Bradley-Cook, J. I.; Burzynski, A.; Hammond, C. R.; Virginia, R. A.

    2011-12-01

    Multiple direct and indirect pathways underlie the association between land cover classification, temperature and soil respiration. Temperature is a main control of the biological processes that constitute soil respiration, yet the effect of changing atmospheric temperatures on soil carbon flux is unresolved. This study examines associations amongst land cover, soil carbon characteristics, soil respiration, and temperature in an Arctic tundra landscape in western Greenland. We used a 1.34 meter resolution multi-spectral WorldView2 satellite image to conduct an unsupervised multi-staged ISODATA classification to characterize land cover heterogeneity. The four band image was taken on July 10th, 2010, and captures an 18 km by 15 km area in the vicinity of Kangerlussuaq. The four major terrestrial land cover classes identified were: shrub-dominated, graminoid-dominated, mixed vegetation, and bare soil. The bare soil class was comprised of patches where surface soil has been deflated by wind and ridge-top fellfield. We hypothesize that soil respiration and soil carbon storage are associated with land cover classification and temperature. We set up a hierarchical field sampling design to directly observe spatial variation between and within land cover classes along a 20 km temperature gradient extending west from Russell Glacier on the margin of the Greenland Ice Sheet. We used the land cover classification map and ground verification to select nine sites, each containing patches of the four land cover classes. Within each patch we collected soil samples from a 50 cm pit, quantified vegetation, measured active layer depth and determined landscape characteristics. From a subset of field sites we collected additional 10 cm surface soil samples to estimate soil heterogeneity within patches and measured soil respiration using a LiCor 8100 Infrared Gas Analyzer. Soil respiration rates varied with land cover classes, with values ranging from 0.2 mg C/m^2/hr in the bare soil

  12. Diel pattern of soil respiration in N-amended soil under maize cultivation

    NASA Astrophysics Data System (ADS)

    Ding, Weixin; Cai, Yan; Cai, Zucong; Zheng, Xunhua

    To understand maize- and N-induced diel variations in CO 2 emission, we examined hourly CO 2 emissions during the three typical growth stages of maize in sandy loam soil. There was a distinct diel pattern in soil CO 2 emissions, with the peak occurring between 14:00 and 18:00 and the trough occurring between 0:00 and 4:00. Maize presence delayed the time of the peak. The absolute amount and diel fluctuation of CO 2 emissions tended to diminish with time in the bare soil fertilized with 150 kg N ha -1 (BS). In contrast, N-fertilized maize (N150) significantly enhanced the total amount of CO 2 emissions and the peak-trough differences in CO 2 emissions, which reached a maximum at the pollination stage and then decreased. Control soil (CK) containing maize but no N fertilizer had highest overall CO 2 emissions but reduced diel fluctuation because rhizosphere respiration was elevated in the nighttime. Soil temperature accounted for 61-71% of diel variation in the BS treatment but for only 44-59% and 38-58% in the N150 and CK treatments, respectively. Photosynthesis rates affected diel variation at the seedling and pollination stages. Both temperature and photosynthesis rates together explained up to 67-84% of diel variation at the seedling and pollination stages in the N150 treatment, but only 61% at the seedling stage in the CK treatment due to more CO 2 released in the nighttime. The increased nighttime CO 2 release, in turn, decreased the effect of temperature and even reduced the influence of photosynthesis rate on diel variations in CO 2 release. Based on the present results, the best time for obtaining a representative daily CO 2 measurement was found to be approximately 8:00 at the seedling stage and 9:00-11:00 at the other growth stages. The current findings indicate that N addition reduces soil CO 2 emissions and its diel fluctuation.

  13. Not so hot: Rapid recovery of soil temperature and respiration following tornado damage, regardless of disturbance severity

    NASA Astrophysics Data System (ADS)

    Nagendra, U.; Peterson, C.

    2013-12-01

    Forest disturbances such as tornadoes are expected to raise soil temperatures and increase soil respiration. Opening canopy gaps allows solar radiation to heat the forest floor, and damaged plant roots provide fuel for decomposition. Patches of disturbed forest can range from low severity (some defoliation, broken branches) to high severity (uprooted or snapped trees). Disturbance severity affects plant population and community processes, such as regeneration mode, species diversity, and community structure. We expect disturbance severity to also affect ecosystem processes such as soil respiration. Severe disturbances cause more distinct, and often larger, canopy gaps than mild disturbances, and damage more standing biomass, both above- and below-ground. We would expect these larger gaps and greater litter amounts to increase soil temperature and respiration in more severely disturbed forest patches. In April 2011, a moderate (EF-3) tornado damaged portions of the Chattahoochee National Forest in NE Georgia, USA. Our lab has been characterizing the damage and regeneration in sections of the forest since summer 2011. In Spring 2013, we installed 4 iButton temperature sensors in each of 14 plots across a range of disturbance severity (for a total of 56 sensors). Severity was determined by percent of initial tree basal area downed by the tornado, and ranged from 8% to 100% basal area down. The iButtons monitored soil temperature at a depth of 5 cm every hour for 85 days. In July 2013, integrated 24-hour soil respiration was measured at the same locations using soda lime absorption in sealed PVC collars. Soil temperature at 5 cm averaged 12.66 °C. Contrary to expectations, average daily temperatures did not increase with greater plot damage severity (R2 = 0.001). Daily variation was only slightly higher in plots of very high severity. Overall, soil temperatures appeared to have returned to pre-disturbance temperatures more quickly than expected. Results for upcoming

  14. Soil respiration in northern forests exposed to elevated atmospheric carbon dioxide and ozone.

    PubMed

    Pregitzer, Kurt; Loya, Wendy; Kubiske, Mark; Zak, Donald

    2006-06-01

    The aspen free-air CO2 and O3 enrichment (FACTS II-FACE) study in Rhinelander, Wisconsin, USA, is designed to understand the mechanisms by which young northern deciduous forest ecosystems respond to elevated atmospheric carbon dioxide (CO2) and elevated tropospheric ozone (O3) in a replicated, factorial, field experiment. Soil respiration is the second largest flux of carbon (C) in these ecosystems, and the objective of this study was to understand how soil respiration responded to the experimental treatments as these fast-growing stands of pure aspen and birch + aspen approached maximum leaf area. Rates of soil respiration were typically lowest in the elevated O3 treatment. Elevated CO2 significantly stimulated soil respiration (8-26%) compared to the control treatment in both community types over all three growing seasons. In years 6-7 of the experiment, the greatest rates of soil respiration occurred in the interaction treatment (CO2 + O3), and rates of soil respiration were 15-25% greater in this treatment than in the elevated CO2 treatment, depending on year and community type. Two of the treatments, elevated CO2 and elevated CO2 + O3, were fumigated with 13C-depleted CO2, and in these two treatments we used standard isotope mixing models to understand the proportions of new and old C in soil respiration. During the peak of the growing season, C fixed since the initiation of the experiment in 1998 (new C) accounted for 60-80% of total soil respiration. The isotope measurements independently confirmed that more new C was respired from the interaction treatment compared to the elevated CO2 treatment. A period of low soil moisture late in the 2003 growing season resulted in soil respiration with an isotopic signature 4-6 per thousand enriched in 13C compared to sample dates when the percentage soil moisture was higher. In 2004, an extended period of low soil moisture during August and early September, punctuated by a significant rainfall event, resulted in soil

  15. Soil respiration in northern forests exposed to elevated atmospheric carbon dioxide and ozone.

    PubMed

    Pregitzer, Kurt; Loya, Wendy; Kubiske, Mark; Zak, Donald

    2006-06-01

    The aspen free-air CO2 and O3 enrichment (FACTS II-FACE) study in Rhinelander, Wisconsin, USA, is designed to understand the mechanisms by which young northern deciduous forest ecosystems respond to elevated atmospheric carbon dioxide (CO2) and elevated tropospheric ozone (O3) in a replicated, factorial, field experiment. Soil respiration is the second largest flux of carbon (C) in these ecosystems, and the objective of this study was to understand how soil respiration responded to the experimental treatments as these fast-growing stands of pure aspen and birch + aspen approached maximum leaf area. Rates of soil respiration were typically lowest in the elevated O3 treatment. Elevated CO2 significantly stimulated soil respiration (8-26%) compared to the control treatment in both community types over all three growing seasons. In years 6-7 of the experiment, the greatest rates of soil respiration occurred in the interaction treatment (CO2 + O3), and rates of soil respiration were 15-25% greater in this treatment than in the elevated CO2 treatment, depending on year and community type. Two of the treatments, elevated CO2 and elevated CO2 + O3, were fumigated with 13C-depleted CO2, and in these two treatments we used standard isotope mixing models to understand the proportions of new and old C in soil respiration. During the peak of the growing season, C fixed since the initiation of the experiment in 1998 (new C) accounted for 60-80% of total soil respiration. The isotope measurements independently confirmed that more new C was respired from the interaction treatment compared to the elevated CO2 treatment. A period of low soil moisture late in the 2003 growing season resulted in soil respiration with an isotopic signature 4-6 per thousand enriched in 13C compared to sample dates when the percentage soil moisture was higher. In 2004, an extended period of low soil moisture during August and early September, punctuated by a significant rainfall event, resulted in soil

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

    NASA Astrophysics Data System (ADS)

    Deng, Q.; Zhou, G.; Liu, J.; Liu, S.; Duan, H.; Zhang, D.

    2010-01-01

    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

  17. [Soil microbial biomass and respiration rate under effects of different planting patterns of peanut].

    PubMed

    Lin, Ying-jie; Gao, Fang; Zhang, Jia-lei; Zhou, Lu-ying; Zhang, Xin-min; Li, Bao-long; Zhao, Hua-jian; Li, Xiang-dong

    2010-09-01

    A field experiment with randomized design was conducted to study the effects of six planting patterns of peanut, i.e., spring sowing and plastic film mulching, spring sowing and open cultivation, summer sowing and plastic film mulching, summer sowing and open cultivation, intercropped in wheat field, and control of intercropped in wheat field, on soil microbial biomass C, soil active microbial biomass, and soil respiration rate. The results showed that the growth stage and planting pattern of peanut had significant effects on soil microbial biomass and respiration rate. With the prolonged time after anthesis, soil microbial biomass C, active microbial biomass, and respiration rate increased gradually, peaked at pod-setting stage, and decreased then. Open cultivation enhanced soil microbial biomass C and respiration rate but reduced soil active microbial biomass, being unfavorable to soil nutrient transformation and nutrient availability, while plastic film mulching increased soil active microbial biomass, and consequently, promoted soil nutrient transformation and nutrient availability. Comparing with intercropped in wheat field and open cultivation, intercropped in wheat field and plastic film mulching increased soil microbial biomass C, active microbial biomass, and respiration rate, which immobilized more soil nutrients and was not conducive to peanut growth.

  18. Temperature sensitivity of soil respiration rates enhanced by microbial community response.

    PubMed

    Karhu, Kristiina; Auffret, Marc D; Dungait, Jennifer A J; Hopkins, David W; Prosser, James I; Singh, Brajesh K; Subke, Jens-Arne; Wookey, Philip A; Agren, Göran I; Sebastià, Maria-Teresa; Gouriveau, Fabrice; Bergkvist, Göran; Meir, Patrick; Nottingham, Andrew T; Salinas, Norma; Hartley, Iain P

    2014-09-01

    Soils store about four times as much carbon as plant biomass, and soil microbial respiration releases about 60 petagrams of carbon per year to the atmosphere as carbon dioxide. Short-term experiments have shown that soil microbial respiration increases exponentially with temperature. This information has been incorporated into soil carbon and Earth-system models, which suggest that warming-induced increases in carbon dioxide release from soils represent an important positive feedback loop that could influence twenty-first-century climate change. The magnitude of this feedback remains uncertain, however, not least because the response of soil microbial communities to changing temperatures has the potential to either decrease or increase warming-induced carbon losses substantially. Here we collect soils from different ecosystems along a climate gradient from the Arctic to the Amazon and investigate how microbial community-level responses control the temperature sensitivity of soil respiration. We find that the microbial community-level response more often enhances than reduces the mid- to long-term (90 days) temperature sensitivity of respiration. Furthermore, the strongest enhancing responses were observed in soils with high carbon-to-nitrogen ratios and in soils from cold climatic regions. After 90 days, microbial community responses increased the temperature sensitivity of respiration in high-latitude soils by a factor of 1.4 compared to the instantaneous temperature response. This suggests that the substantial carbon stores in Arctic and boreal soils could be more vulnerable to climate warming than currently predicted. PMID:25186902

  19. Temperature sensitivity of soil respiration rates enhanced by microbial community response.

    PubMed

    Karhu, Kristiina; Auffret, Marc D; Dungait, Jennifer A J; Hopkins, David W; Prosser, James I; Singh, Brajesh K; Subke, Jens-Arne; Wookey, Philip A; Agren, Göran I; Sebastià, Maria-Teresa; Gouriveau, Fabrice; Bergkvist, Göran; Meir, Patrick; Nottingham, Andrew T; Salinas, Norma; Hartley, Iain P

    2014-09-01

    Soils store about four times as much carbon as plant biomass, and soil microbial respiration releases about 60 petagrams of carbon per year to the atmosphere as carbon dioxide. Short-term experiments have shown that soil microbial respiration increases exponentially with temperature. This information has been incorporated into soil carbon and Earth-system models, which suggest that warming-induced increases in carbon dioxide release from soils represent an important positive feedback loop that could influence twenty-first-century climate change. The magnitude of this feedback remains uncertain, however, not least because the response of soil microbial communities to changing temperatures has the potential to either decrease or increase warming-induced carbon losses substantially. Here we collect soils from different ecosystems along a climate gradient from the Arctic to the Amazon and investigate how microbial community-level responses control the temperature sensitivity of soil respiration. We find that the microbial community-level response more often enhances than reduces the mid- to long-term (90 days) temperature sensitivity of respiration. Furthermore, the strongest enhancing responses were observed in soils with high carbon-to-nitrogen ratios and in soils from cold climatic regions. After 90 days, microbial community responses increased the temperature sensitivity of respiration in high-latitude soils by a factor of 1.4 compared to the instantaneous temperature response. This suggests that the substantial carbon stores in Arctic and boreal soils could be more vulnerable to climate warming than currently predicted.

  20. Variation in Soil Respiration Across an Alpine Soil Moisture and Vegetation Community Gradient at Niwot Ridge, Colorado

    NASA Astrophysics Data System (ADS)

    Knowles, J. F.; Blanken, P.; Williams, M. W.

    2014-12-01

    The alpine tundra is a mosaic of comingled vegetation communities that vary predominantly as a function of landscape position, micro-scale topography, subsurface permeability, and resultant soil moisture availability. We characterized the spatio-temporal variability of soil respiration from 17 alpine tundra sites across an irregular soil moisture gradient within the footprint of ongoing eddy covariance measurements over the 2011 (wet year) and 2012 (dry year) growing seasons. We then used a soil moisture threshold as a proxy to separate the sites into fellfield, dry/moist meadow, and wet meadow tundra vegetation communities. Soil moisture and soil respiration were significantly correlated across all communities (p << 0.001), but increasing soil moisture invoked a bidirectional response from fellfield and dry/moist meadow communities (directly proportional) relative to wet meadow communities (inversely proportional). Soil temperature and soil respiration were not significantly correlated. Linearly interpolating between sampling dates, the cumulative soil respiration flux over the two growing seasons ranged from 595 to 3177 g CO2 m-2, and median fluxes were 1114, 1679, and 1400 g CO2 m-2 for fellfield, dry/moist meadow, and wet meadow sites, respectively. Ecosystem respiration from nighttime eddy covariance measurements was 618 g CO2 m-2 over the same period, suggesting that soil respiration fluxes from very dry fellfield tundra disproportionately influenced the eddy covariance data. Overall, cumulative soil respiration was 50% greater in the wet year (2011) relative to the dry year (2012); therefore increased precipitation has the potential to increase soil respiration from alpine tundra as a whole.

  1. Soil respiration under mature deciduous forest trees after 7 years of CO2 enrichment

    NASA Astrophysics Data System (ADS)

    Bader, Martin; Körner, Christian

    2010-05-01

    The anthropogenic rise in atmospheric CO2 is expected to impact carbon fluxes not only at ecosystem level but also at the global scale by altering carbon cycle processes in soils. At the Swiss Canopy Crane (SCC), we examined how 7 years of free air CO2 enrichment (FACE) affected soil CO2 dynamics in a c. 100-year-old mixed deciduous forest. The use of 13C-depleted CO2 for canopy enrichment allowed us to trace the flow of recently fixed carbon (C). In the seventh year of growth at ~550 ppm CO2, soil respiratory CO2 consisted of 39% labelled C. During the growing season, soil air CO2 concentration was significantly enhanced under CO2-exposed trees. However, elevated CO2 failed to stimulate cumulative soil respiration (Rs) over the growing season. We found periodic reductions as well as increases in instantaneous rates of Rs in response to elevated CO2, depending on soil temperature and soil volumetric water content (VWC; significant 3-way interaction). During wet periods, soil water savings under CO2-enriched trees led to excessive VWC (>45%) that suppressed Rs. Elevated CO2 stimulated Rs only when VWC was ≤40% and concurrent soil temperature was high (>15 °C). Seasonal Q10 estimates of Rs were significantly lower under elevated (Q10 = 3.30) compared to ambient CO2 (Q10 = 3.97). However, this effect disappeared when 3 consecutive sampling dates of extremely high VWC were disregarded. This suggests that elevated CO2 affected Q10 mainly indirectly through changes in VWC. Fine root respiration did not differ significantly between treatments but soil microbial biomass (Cmic) increased by 14% under elevated CO2 (marginally significant). Our findings do not indicate enhanced soil C emissions in such stands under future atmospheric CO2. It remains to be shown whether C losses via leaching of dissolved organic or inorganic C (DOC, DIC) help to balance the carbon budget in this forest.

  2. Influence of Soil Tillage Systems on Soil Respiration and Production on Wheat, Maize and Soybean Crop

    NASA Astrophysics Data System (ADS)

    Moraru, P. I.; Rusu, T.

    2012-04-01

    Soil respiration leads to CO2 emissions from soil to the atmosphere, in significant amounts for the global carbon cycle. Soil capacity to produce CO2 varies depending on soil, season, intensity and quality of agrotechnical tillage, soil water, cultivated plant, fertilizer etc. The data presented in this paper were obtained on argic-stagnic Faeoziom (SRTS, 2003). These areas were was our research, presents a medium multiannual temperature of 8.20C, medium of multiannual rain drowns: 613 mm. The experimental variants chosen were: A. Conventional system (CS): V1-reversible plough (22-25 cm)+rotary grape (8-10 cm); B. Minimum tillage system (MT): V2 - paraplow (18-22 cm) + rotary grape (8-10 cm); V3 - chisel (18-22 cm) + rotary grape (8-10 cm);V4 - rotary grape (10-12 cm); C. No-Tillage systems (NT): V5 - direct sowing. The experimental design was a split-plot design with three replications. In one variant the area of a plot was 300 m2. The experimental variants were studied in the 3 years crop rotation: maize - soy-bean - autumn wheat. To soil respiration under different tillage practices, determinations were made for each crop in four vegetative stages (spring, 5-6 leaves, bean forming, harvest) using ACE Automated Soil CO2 Exchange System. Soil respiration varies throughout the year for all three crops of rotation, with a maximum in late spring (1383 to 2480 mmoli m-2s-1) and another in fall (2141 to 2350 mmoli m-2s-1). The determinations confirm the effect of soil tillage system on soil respiration, the daily average is lower at NT (315-1914 mmoli m-2s-1), followed by MT (318-2395 mmoli m-2s-1) and is higher in the CS (321-2480 mmol m-2s-1). Productions obtained at MT and NT don't have significant differences at wheat and are higher at soybean. The differences in crop yields are recorded at maize and can be a direct consequence of loosening, mineralization and intensive mobilization of soil fertility. Acknowledgments: This work was supported by CNCSIS

  3. A novel approach for identifying the true temperature sensitivity from soil respiration measurements

    SciTech Connect

    Gu, Lianhong; Hanson, Paul J; Liu, Qing; Post, Wilfred M

    2008-01-01

    We propose a novel approach, called the localized ratio fitting (LRF), to estimating the true temperature sensitivity from soil respiration measurements, a task crucial to modeling terrestrial carbon cycle and climate but so far hindered by the inadequate conventional regression approach. LRF takes advantage of the different timescales of the pool dynamics Cinduced and environmental variation Cinduced changes in soil CO2 efflux. It first transforms the expression for soil respiration into a form suppressing the influence of soil carbon pool dynamics and then uses the transformed expression to infer the parameters of environmental sensitivities. LRF works best for high-frequency soil respiration measurements and thus is particularly suitable for analyzing time series produced by automated soil chambers and from soil incubation experiments. We evaluated the validity of LRF with both simulated (with a multipool soil organic carbon model driven by realistic plant litter input scenarios) and measured (with automated soil chambers) time series of soil respiration. LRF accurately retrieved the true temperature sensitivity from the simulated heterotrophic soil respiration while the conventional approach failed to do so. The simulation also revealed that LRF performed better than the conventional approach when a direct photosynthetic signal existed in the time series of soil respiration although even LRF could not completely eliminate the interference of photosynthetic contribution for estimating the true temperature sensitivity. Importantly, the simulation on the photosynthetic influence reproduced a typical seasonal pattern of apparent temperature sensitivity reported in the literature: higher sensitivity in winter (dormant season) and lower sensitivity in summer (growing season). Such pattern has been interpreted as an indication of temperature acclimation of soil respiration by previous studies. Our simulation now indicated that that interpretation may be incorrect. The

  4. Variation in winter snowpack depth and duration influences summer soil respiration in a subalpine meadow

    NASA Astrophysics Data System (ADS)

    Arnold, C. L.; Ghezzehei, T. A.; Berhe, A. A.

    2012-12-01

    Subalpine meadows in the Sierra Nevada rely on the depth and duration of the winter snowpack to supply ample water to restore the water table in the meadow during the spring snowmelt. This study examines the role that interannual variability in the winter snowpack plays in the overall rate of summer soil respiration along a hydrologic gradient in a subalpine meadow. Carbon dioxide efflux from the meadow was measured from June through September in 2011 and 2012 using soil collars and a LICOR 8100A infrared gas analyzer. Preliminary results show that soil respiration rates are influenced by the hydrologic gradient across the meadow, with drier regions peaking earlier in the summer as compared to wetter regions. We also show that high snowpack years can suppress soil respiration in the meadow until late in the summer season as compared to low snowpack years, where soil respiration peaks early in the summer.

  5. The impact of hazelnuts in land-use changes on soil carbon and in situ soil respiration dynamics.

    PubMed

    Oral, HasanVolkan; Guney, Mert; Kucuker, Mehmet Ali; Onay, Turgut T; Copty, Nadim K; Mater, Baris; Yenigun, Orhan

    2013-11-15

    Our study assessed the impact of hazelnuts (Coryllus avellena L.) in land-use conversion from forest (F) to agricultural land (AL) on various attributes of soil respiration dynamics, such as soil elemental carbon (C%) content, microbial respiration, bulk density, soil pH, electrical conductivity, and seasonal variations. We developed soil C% models to compare soil C% between F and AL soils. Four field trips were conducted in the winter and summer of 2008 and the spring and fall of 2009 in the Karasu region of Turkey. During each trip, 42 sites were visited F (n = 21) and AL (n = 21). Our results showed that hazelnuts plantations in AL could reduce elemental C% by 27% (winter 2008), 16% (summer 2008), 41% (spring 2009), and 22% (fall 2009) in the four seasons studied when compared to F soils. In situ soil respiration was also reduced by 31% (spring 2008), 67% (fall 2008), 88% (spring 2009), and 79% (fall 2009) in AL soils over F soils. The percent of organic matter of AL soils was declined by 36% (winter 2008), 23% (summer 2008), 34% (spring 2009), and 26% (fall 2009) in comparison to F soils. Significant reductions in the correlation between C%-percent clay and C%-electrical conductivity were also recorded for AL soils over F soils. Furthermore, AL soils showed higher bulk density (7.4% and 7%) when compared to F soils. We also found that in situ soil respiration had significant seasonal correlations (p < 0.05) with soil pH (0.537), soil temperature, and percent clay (-0.486) in F soils (summer 2008, spring 2009). Additionally, we found that seasonal variations of four sampling seasons had a moderate impact on in situ respiration and that the differences were statistically significant, except for the winter-summer and spring-fall seasonal pairs. Linear regression C models showed significant differences for F and AL soils.

  6. Microbial properties explain temporal variation in soil respiration in a grassland subjected to nitrogen addition

    PubMed Central

    Li, Yue; Liu, Yinghui; Wu, Shanmei; Niu, Lei; Tian, Yuqiang

    2015-01-01

    The role of soil microbial variables in shaping the temporal variability of soil respiration has been well acknowledged but is poorly understood, particularly under elevated nitrogen (N) deposition conditions. We measured soil respiration along with soil microbial properties during the early, middle, and late growing seasons in temperate grassland plots that had been treated with N additions of 0, 2, 4, 8, 16, or 32 g N m−2 yr−1 for 10 years. Representing the averages over three observation periods, total (Rs) and heterotrophic (Rh) respiration were highest with 4 g N m−2 yr−1, but autotrophic respiration (Ra) was highest with 8 to 16 g N m−2 yr−1. Also, the responses of Rh and Ra were unsynchronized considering the periods separately. N addition had no significant impact on the temperature sensitivity (Q10) for Rs but inhibited the Q10 for Rh. Significant interactions between observation period and N level occurred in soil respiration components, and the temporal variations in soil respiration components were mostly associated with changes in microbial biomass carbon (MBC) and phospholipid fatty acids (PLFAs). Further observation on soil organic carbon and root biomass is needed to reveal the long-term effect of N deposition on soil C sequestration. PMID:26678303

  7. Microbial properties explain temporal variation in soil respiration in a grassland subjected to nitrogen addition.

    PubMed

    Li, Yue; Liu, Yinghui; Wu, Shanmei; Niu, Lei; Tian, Yuqiang

    2015-12-18

    The role of soil microbial variables in shaping the temporal variability of soil respiration has been well acknowledged but is poorly understood, particularly under elevated nitrogen (N) deposition conditions. We measured soil respiration along with soil microbial properties during the early, middle, and late growing seasons in temperate grassland plots that had been treated with N additions of 0, 2, 4, 8, 16, or 32 g N m(-2) yr(-1) for 10 years. Representing the averages over three observation periods, total (Rs) and heterotrophic (Rh) respiration were highest with 4 g N m(-2) yr(-1), but autotrophic respiration (Ra) was highest with 8 to 16 g N m(-2) yr(-1). Also, the responses of Rh and Ra were unsynchronized considering the periods separately. N addition had no significant impact on the temperature sensitivity (Q10) for Rs but inhibited the Q10 for Rh. Significant interactions between observation period and N level occurred in soil respiration components, and the temporal variations in soil respiration components were mostly associated with changes in microbial biomass carbon (MBC) and phospholipid fatty acids (PLFAs). Further observation on soil organic carbon and root biomass is needed to reveal the long-term effect of N deposition on soil C sequestration.

  8. Microbial properties explain temporal variation in soil respiration in a grassland subjected to nitrogen addition

    NASA Astrophysics Data System (ADS)

    Li, Yue; Liu, Yinghui; Wu, Shanmei; Niu, Lei; Tian, Yuqiang

    2015-12-01

    The role of soil microbial variables in shaping the temporal variability of soil respiration has been well acknowledged but is poorly understood, particularly under elevated nitrogen (N) deposition conditions. We measured soil respiration along with soil microbial properties during the early, middle, and late growing seasons in temperate grassland plots that had been treated with N additions of 0, 2, 4, 8, 16, or 32 g N m-2 yr-1 for 10 years. Representing the averages over three observation periods, total (Rs) and heterotrophic (Rh) respiration were highest with 4 g N m-2 yr-1, but autotrophic respiration (Ra) was highest with 8 to 16 g N m-2 yr-1. Also, the responses of Rh and Ra were unsynchronized considering the periods separately. N addition had no significant impact on the temperature sensitivity (Q10) for Rs but inhibited the Q10 for Rh. Significant interactions between observation period and N level occurred in soil respiration components, and the temporal variations in soil respiration components were mostly associated with changes in microbial biomass carbon (MBC) and phospholipid fatty acids (PLFAs). Further observation on soil organic carbon and root biomass is needed to reveal the long-term effect of N deposition on soil C sequestration.

  9. Contrasting effects of nitrogen and phosphorus addition on soil respiration in an alpine grassland on the Qinghai-Tibetan Plateau

    PubMed Central

    Ren, Fei; Yang, Xiaoxia; Zhou, Huakun; Zhu, Wenyan; Zhang, Zhenhua; Chen, Litong; Cao, Guangmin; He, Jin-Sheng

    2016-01-01

    High soil organic carbon content, extensive root biomass, and low nutrient availability make alpine grasslands an important ecosystem for assessing the influence of nutrient enrichment on soil respiration (SR). We conducted a four-year (2009–2012) field experiment in an alpine grassland on the Qinghai-Tibetan Plateau to examine the individual and combined effects of nitrogen (N, 100 kg ha−1year−1) and phosphorus (P, 50 kg ha−1year−1) addition on SR. We found that both N and P addition did not affect the overall growing-season SR but effects varied by year: with N addition SR increased in the first year but decreased during the last two years. However, while P addition did not affect SR during the first two years, SR increased during the last two years. No interactive effects of N and P addition were observed, and both N addition and P addition reduced heterotrophic respiration during the last year of the experiment. N and P addition affected SR via different processes: N mainly affected heterotrophic respiration, whereas P largely influenced autotrophic respiration. Our results highlight the divergent effects of N and P addition on SR and address the important potential of P enrichment for regulating SR and the carbon balance in alpine grasslands. PMID:27721415

  10. Complex terrain alters temperature and moisture limitations of forest soil respiration across a semiarid to subalpine gradient

    USGS Publications Warehouse

    Berryman, Erin Michele; Barnard, H.R.; Adams, H.R.; Burns, M.A.; Gallo, E.; Brooks, P.D.

    2015-01-01

    Forest soil respiration is a major carbon (C) flux that is characterized by significant variability in space and time. We quantified growing season soil respiration during both a drought year and a nondrought year across a complex landscape to identify how landscape and climate interact to control soil respiration. We asked the following questions: (1) How does soil respiration vary across the catchments due to terrain-induced variability in moisture availability and temperature? (2) Does the relative importance of moisture versus temperature limitation of respiration vary across space and time? And (3) what terrain elements are important for dictating the pattern of soil respiration and its controls? Moisture superseded temperature in explaining watershed respiration patterns, with wetter yet cooler areas higher up and on north facing slopes yielding greater soil respiration than lower and south facing areas. Wetter subalpine forests had reduced moisture limitation in favor of greater seasonal temperature limitation, and the reverse was true for low-elevation semiarid forests. Coincident climate poorly predicted soil respiration in the montane transition zone; however, antecedent precipitation from the prior 10 days provided additional explanatory power. A seasonal trend in respiration remained after accounting for microclimate effects, suggesting that local climate alone may not adequately predict seasonal variability in soil respiration in montane forests. Soil respiration climate controls were more strongly related to topography during the drought year highlighting the importance of landscape complexity in ecosystem response to drought.

  11. Sustained stimulation of soil respiration and CO2 release from an agricultural soil after 10 years of experimental warming

    NASA Astrophysics Data System (ADS)

    Munch, Jean Charles; Graf, Wolfgang; Reichenstein, Markus; Reth, Sascha

    2010-05-01

    A number of forest and grassland studies indicated that stimulation of the soil respiration by soil warming ceases after a couple of years (Luo et al 2001). A long-term soil warming lysimeter experiment (soil monolythes from an agricultural field, 1m2 x 2 Meter depth, temperature = ambient + 3°C; with a regionally usual crop rotation with 5 crops) was conducted in southern Germany. It results in a sustained stimulation of soil respiration after 10 years. Moreover, both warmed and control treatments exhibited a similar temperature response of soil respiration indicating that adaptation in terms of temperature sensitivity was absent. Carbon dioxide concentration measurements within the profiles are supporting these findings. The increased soil respiration occurred although vegetation productivity in the warmed treatment was not higher than in the control plots. These findings strongly contrast current soil carbon modeling concepts, where carbon pools decay according to first-order kinetics, and thus a depletion of labile soil carbon pools leads to an apparent down-regulation of microbial respiration (Knorr et al 2005). Consequently, the potential for positive carbon-climate cycle feedback may be larger than represented in current models of soil carbon turnover and in general assessments. Literatur Knorr W, Prentice I C, House J I and Holland A 2005 Long-term sensitivity of soil carbon turnover to warming Nature 433 298-301 Luo Y, Wan S, Hui D and Wallace L L 2001 Acclimatization of soil respiration to warming in a tall grass prairie Nature 413 622 - 5 Reth S. Graf W, Reichenstein M, Munch J.C. 2009 Sustained stimulation of soil respiration after 10 years of experimental warming Environmental Research Letters 4(2) 024005

  12. Management Effects on Soil Respiration in North Carolina Coastal Plain Loblolly Pine Plantations

    NASA Astrophysics Data System (ADS)

    Gavazzi, M.; McNulty, S.; Noormets, A.; Treasure, E.

    2012-12-01

    Loblolly pine is the most widely planted tree for plantation management in the southern US. In the southern coastal plain, where much of the original longleaf pine and bottomland hardwood forests have been converted to loblolly pine plantations, inland areas are commonly characterized by deep organic soils that can store up to 80 kg C m-2. Intensive management activities on these sites disturb the forest floor and soil and their impact on soil respiration rates and long term soil storage capabilities is unclear. We measured soil respiration rates in three loblolly pine plantations being managed with a combination of ditching, bedding, clearcutting, thinning and fertilization. Sites and management regimes represented a wide range of real world conditions found in managed southern US forestry plantations. Soil efflux rates along with soil temperature and moisture were measured throughout the year at four to six plots on each site and best fit relationships were developed. Annual soil respiration rates where modeled using 30-minute soil temperature and moisture measurements recorded at a centralized meteorological station on each site. Soil efflux rates were highly correlated with soil temperature and moisture, but interaction between the two effects was uncommon. Soil temperature was the primary driver of soil respiration rates, but rates were suppressed under high soil moisture content. Modeled annual soil efflux rates were higher the first two years following clearcut harvest and thinning operations, but lower two years following fertilization. Rates were lower in the gaps, where entire tree rows were removed, compared to thinned areas, especially on the unfertilized site. Results indicate that soil respiration rates can be strongly impacted by forest management practices; however, the period of increased soil CO2 efflux due to site disturbance may last only a few years.

  13. Improving Estimations of Spatial Distribution of Soil Respiration Using the Bayesian Maximum Entropy Algorithm and Soil Temperature as Auxiliary Data

    PubMed Central

    Hu, Junguo; Zhou, Jian; Zhou, Guomo; Luo, Yiqi; Xu, Xiaojun; Li, Pingheng; Liang, Junyi

    2016-01-01

    Soil respiration inherently shows strong spatial variability. It is difficult to obtain an accurate characterization of soil respiration with an insufficient number of monitoring points. However, it is expensive and cumbersome to deploy many sensors. To solve this problem, we proposed employing the Bayesian Maximum Entropy (BME) algorithm, using soil temperature as auxiliary information, to study the spatial distribution of soil respiration. The BME algorithm used the soft data (auxiliary information) effectively to improve the estimation accuracy of the spatiotemporal distribution of soil respiration. Based on the functional relationship between soil temperature and soil respiration, the BME algorithm satisfactorily integrated soil temperature data into said spatial distribution. As a means of comparison, we also applied the Ordinary Kriging (OK) and Co-Kriging (Co-OK) methods. The results indicated that the root mean squared errors (RMSEs) and absolute values of bias for both Day 1 and Day 2 were the lowest for the BME method, thus demonstrating its higher estimation accuracy. Further, we compared the performance of the BME algorithm coupled with auxiliary information, namely soil temperature data, and the OK method without auxiliary information in the same study area for 9, 21, and 37 sampled points. The results showed that the RMSEs for the BME algorithm (0.972 and 1.193) were less than those for the OK method (1.146 and 1.539) when the number of sampled points was 9 and 37, respectively. This indicates that the former method using auxiliary information could reduce the required number of sampling points for studying spatial distribution of soil respiration. Thus, the BME algorithm, coupled with soil temperature data, can not only improve the accuracy of soil respiration spatial interpolation but can also reduce the number of sampling points. PMID:26807579

  14. Improving Estimations of Spatial Distribution of Soil Respiration Using the Bayesian Maximum Entropy Algorithm and Soil Temperature as Auxiliary Data.

    PubMed

    Hu, Junguo; Zhou, Jian; Zhou, Guomo; Luo, Yiqi; Xu, Xiaojun; Li, Pingheng; Liang, Junyi

    2016-01-01

    Soil respiration inherently shows strong spatial variability. It is difficult to obtain an accurate characterization of soil respiration with an insufficient number of monitoring points. However, it is expensive and cumbersome to deploy many sensors. To solve this problem, we proposed employing the Bayesian Maximum Entropy (BME) algorithm, using soil temperature as auxiliary information, to study the spatial distribution of soil respiration. The BME algorithm used the soft data (auxiliary information) effectively to improve the estimation accuracy of the spatiotemporal distribution of soil respiration. Based on the functional relationship between soil temperature and soil respiration, the BME algorithm satisfactorily integrated soil temperature data into said spatial distribution. As a means of comparison, we also applied the Ordinary Kriging (OK) and Co-Kriging (Co-OK) methods. The results indicated that the root mean squared errors (RMSEs) and absolute values of bias for both Day 1 and Day 2 were the lowest for the BME method, thus demonstrating its higher estimation accuracy. Further, we compared the performance of the BME algorithm coupled with auxiliary information, namely soil temperature data, and the OK method without auxiliary information in the same study area for 9, 21, and 37 sampled points. The results showed that the RMSEs for the BME algorithm (0.972 and 1.193) were less than those for the OK method (1.146 and 1.539) when the number of sampled points was 9 and 37, respectively. This indicates that the former method using auxiliary information could reduce the required number of sampling points for studying spatial distribution of soil respiration. Thus, the BME algorithm, coupled with soil temperature data, can not only improve the accuracy of soil respiration spatial interpolation but can also reduce the number of sampling points. PMID:26807579

  15. Effect of exogenous phosphorus addition on soil respiration in Calamagrostis angustifolia freshwater marshes of Northeast China

    NASA Astrophysics Data System (ADS)

    Song, Changchun; Liu, Deyan; Song, Yanyu; Yang, Guisheng; Wan, Zhongmei; Li, Yingchen; Xu, Xiaofeng

    2011-03-01

    Anthropogenic activities have increased phosphorus (P) inputs to wetland ecosystems. However, little is known about the effect of P enrichment on soil respiration in these ecosystems. To understand the effect of P enrichment on soil respiration, we conducted a field experiment in Calamagrostis angustifolia-dominated freshwater marshes, the Sanjiang Plain, Northeast China. We investigated soil respiration in the first growing season after P addition at four rates (0, 1.2, 4.8 and 9.6 g P m-2 year-1). In addition, we also examined aboveground biomass, soil labile C fractions (dissolved organic C, DOC; microbial biomass C, MBC; easily oxidizable C, EOC) and enzyme activities (invertase, urease and acid phosphatase activities) following one year of P addition. P addition decreased soil respiration during the growing season. Dissolved organic C in soil pore water increased after P addition at both 5 and 15 cm depths. Moreover, increased P input generally inhibited soil MBC and enzyme activities, and had no effects on aboveground biomass and soil EOC. Our results suggest that, in the short-term, soil respiration declines under P enrichment in C. angustifolia-dominated freshwater marshes of Northeast China, and its extent varies with P addition levels.

  16. Soil respiration dynamics under reduced rainfall in a eucalypt forest ecosystem in SE-Australia

    NASA Astrophysics Data System (ADS)

    Hinko-Najera, N.; Arndt, S. K.; Livesley, S. J.; Fest, B.

    2011-12-01

    Soil respiration is the major pathway by which CO2 is released from a forest ecosystem to the atmosphere. Hence it is a central part of the carbon balance and carbon sink strengths of forests. Soil respiration shows high spatial and temporal variability and is dependent on soil temperature and soil moisture. Its component fluxes are controlled by different carbon sources: decomposition of soil organic matter or litter (heterotrophic respiration) or allocation of assimilated carbon belowground (autotrophic respiration). As such, these processes may respond differently to environmental change. Heatwaves, fires and reduced rainfall are predicted to increase in frequency and intensity in south-eastern Australia. It is not clear how soil respiration processes will respond to this changing climate and the implications for Australia's forest carbon balance. Soil respiration has been measured under reduced rainfall treatments and control plots using closed-dynamic manual chambers linked to a Cavity Ring-Down Spectrometer in a temperate dry eucalypt forest. In addition soil greenhouse gas dynamics are monitored using automated chambers linked to a Fourier Transform Infra Red spectrometer. Forest net carbon exchange is determined using eddy-covariance measurements as part of a long-term ecosystem research project. This presentation focuses on data collected using manual chambers where soil respiration and its component heterotrophic (root exclusion), autotrophic (indirectly) and litter decomposition (indirectly) fluxes have been measured for 1.5 years with regards to their 1) spatial variability, 2) environmental drivers and 3) response to reduced rainfall (40%). First results show total soil respiration (TSR) decreased on average by 16% under reduced rainfall treatment and varied with season according to soil temperature with lowest rates during winter/autumn and highest rates during spring/summer. The contribution of heterotrophic respiration (RH) was on average 28% and

  17. Continuous soil respiration at the Prairie Heating and Elevated CO2 site using forced diffusion chambers

    NASA Astrophysics Data System (ADS)

    Pendall, E.; Brennan, A. L.; Risk, D. A.; Carrillo, Y.

    2012-12-01

    Temporal variations in soil respiration are regulated by changes in soil temperature, moisture and plant phenological activity. These drivers are expected to vary with climate changes including elevated atmospheric CO2 and warming, but it is unknown whether the relationships between the drivers and soil CO2 efflux change with climate change. We studied diurnal to seasonal patterns of soil respiration and its drivers in mixed C3/C4 grassland at the Prairie Heating and CO2 Enrichment (PHACE) site near Cheyenne, WY, where Free-Air CO2 Enrichment is applied at 600 ppm during daytime in the growing season, and temperature is elevated by 1.5/3 deg C day/night all year. We deployed pairs of forced diffusion (FD) chambers in plots with intact and plant-free grassland, exposed to elevated CO2, warming, and ambient climate (six treatments total). Fluxes from intact grassland plots reflected contributions from root and microbial respiration (referred to as soil respiration), while those from plant-free plots reflected only microbial respiration. Non-dispersive infrared CO2 sensors (Vaisala GMT222, Helsinki, Finland) were installed inside the chambers, which had rims inserted 2-cm into the soil. Three sensors were installed in chambers that were not in contact with the soil surface, which recorded atmospheric CO2 concentrations. Soil respiration rates were calculated as the concentration difference between the soil and air chambers times the forced diffusivity factor, which was set by the semi-permeable membrane and calibrated for individual chambers. The objectives of this research were to evaluate the feasibility of this method for determination of continuous fluxes in semi-arid grassland by comparison with established methods, and to compare temporal dynamics and response functions of soil respiration to environmental drivers across the six treatments. We found that fluxes from the forced diffusion chambers compared well with those from an established, closed, dynamic

  18. Mitochondrial haplotype divergences affect specific temperature sensitivity of mitochondrial respiration.

    PubMed

    Pichaud, Nicolas; Ballard, J William O; Tanguay, Robert M; Blier, Pierre U

    2013-02-01

    The aim of this study was to investigate the effect of temperature changes on the functional properties of mitochondria from two sets of D. simulans fly lines harboring the siII and siIII haplotypes in a common nuclear genetic background. We studied four introgressed isofemale lines possessing the mtDNA of siII and the nuclear background of siIII (siII-introgressed) and four lines possessing siIII mitochondria with its native nuclear genome (siIII-controls). We assessed the catalytic capacities of electron transport system (ETS) at four different temperatures (12, 18, 24 and 28 ºC). The impact of temperature on the pyruvate dehydrogenase (PDH) activity, the mitochondrial respiration (coupled and uncoupled respiration), cytochrome c oxidase activity, as well as the excess capacity of complex IV (COX) were evaluated in these two sets of flies. Our results showed that the temperature coefficient values (Q(10)) measured for mitochondrial respiration in the lower range of temperatures (12 to 18 ºC) showed a 2 to 3 fold increase in siII-introgressed when compared to siIII-controls. This result shows that the impact of temperature on mitochondrial function is different between the two mitotypes studied. The Q(10) results seem to be linked to the apparent COX excess capacity of 193% for siIII-controls that is inexistent for siII-introgressed at 12 ºC. One explanation for these results is that the mitochondria can compensate for the disruption of mito-nuclear interactions at 24 ºC but not at lower temperatures. An alternate explanation would be that siII haplotype confer divergent kinetic properties to the ETS that translate to different temperature sensitivities.

  19. Mitochondrial haplotype divergences affect specific temperature sensitivity of mitochondrial respiration.

    PubMed

    Pichaud, Nicolas; Ballard, J William O; Tanguay, Robert M; Blier, Pierre U

    2013-02-01

    The aim of this study was to investigate the effect of temperature changes on the functional properties of mitochondria from two sets of D. simulans fly lines harboring the siII and siIII haplotypes in a common nuclear genetic background. We studied four introgressed isofemale lines possessing the mtDNA of siII and the nuclear background of siIII (siII-introgressed) and four lines possessing siIII mitochondria with its native nuclear genome (siIII-controls). We assessed the catalytic capacities of electron transport system (ETS) at four different temperatures (12, 18, 24 and 28 ºC). The impact of temperature on the pyruvate dehydrogenase (PDH) activity, the mitochondrial respiration (coupled and uncoupled respiration), cytochrome c oxidase activity, as well as the excess capacity of complex IV (COX) were evaluated in these two sets of flies. Our results showed that the temperature coefficient values (Q(10)) measured for mitochondrial respiration in the lower range of temperatures (12 to 18 ºC) showed a 2 to 3 fold increase in siII-introgressed when compared to siIII-controls. This result shows that the impact of temperature on mitochondrial function is different between the two mitotypes studied. The Q(10) results seem to be linked to the apparent COX excess capacity of 193% for siIII-controls that is inexistent for siII-introgressed at 12 ºC. One explanation for these results is that the mitochondria can compensate for the disruption of mito-nuclear interactions at 24 ºC but not at lower temperatures. An alternate explanation would be that siII haplotype confer divergent kinetic properties to the ETS that translate to different temperature sensitivities. PMID:23054075

  20. Impact of treated wastewater on growth, respiration and hydraulic conductivity of citrus root systems in light and heavy soils.

    PubMed

    Paudel, Indira; Cohen, Shabtai; Shaviv, Avi; Bar-Tal, Asher; Bernstein, Nirit; Heuer, Bruria; Ephrath, Jhonathan

    2016-06-01

    Roots interact with soil properties and irrigation water quality leading to changes in root growth, structure and function. We studied these interactions in an orchard and in lysimeters with clay and sandy loam soils. Minirhizotron imaging and manual sampling showed that root growth was three times lower in the clay relative to sandy loam soil. Treated wastewater (TWW) led to a large reduction in root growth with clay (45-55%) but not with sandy loam soil (<20%). Treated wastewater increased salt uptake, membrane leakage and proline content, and decreased root viability, carbohydrate content and osmotic potentials in the fine roots, especially in clay. These results provide evidence that TWW challenges and damages the root system. The phenology and physiology of root orders were studied in lysimeters. Soil type influenced diameter, specific root area, tissue density and cortex area similarly in all root orders, while TWW influenced these only in clay soil. Respiration rates were similar in both soils, and root hydraulic conductivity was severely reduced in clay soil. Treated wastewater increased respiration rate and reduced hydraulic conductivity of all root orders in clay but only of the lower root orders in sandy loam soil. Loss of hydraulic conductivity increased with root order in clay and clay irrigated with TWW. Respiration and hydraulic properties of all root orders were significantly affected by sodium-amended TWW in sandy loam soil. These changes in root order morphology, anatomy, physiology and hydraulic properties indicate rapid and major modifications of root systems in response to differences in soil type and water quality.

  1. Impact of treated wastewater on growth, respiration and hydraulic conductivity of citrus root systems in light and heavy soils.

    PubMed

    Paudel, Indira; Cohen, Shabtai; Shaviv, Avi; Bar-Tal, Asher; Bernstein, Nirit; Heuer, Bruria; Ephrath, Jhonathan

    2016-06-01

    Roots interact with soil properties and irrigation water quality leading to changes in root growth, structure and function. We studied these interactions in an orchard and in lysimeters with clay and sandy loam soils. Minirhizotron imaging and manual sampling showed that root growth was three times lower in the clay relative to sandy loam soil. Treated wastewater (TWW) led to a large reduction in root growth with clay (45-55%) but not with sandy loam soil (<20%). Treated wastewater increased salt uptake, membrane leakage and proline content, and decreased root viability, carbohydrate content and osmotic potentials in the fine roots, especially in clay. These results provide evidence that TWW challenges and damages the root system. The phenology and physiology of root orders were studied in lysimeters. Soil type influenced diameter, specific root area, tissue density and cortex area similarly in all root orders, while TWW influenced these only in clay soil. Respiration rates were similar in both soils, and root hydraulic conductivity was severely reduced in clay soil. Treated wastewater increased respiration rate and reduced hydraulic conductivity of all root orders in clay but only of the lower root orders in sandy loam soil. Loss of hydraulic conductivity increased with root order in clay and clay irrigated with TWW. Respiration and hydraulic properties of all root orders were significantly affected by sodium-amended TWW in sandy loam soil. These changes in root order morphology, anatomy, physiology and hydraulic properties indicate rapid and major modifications of root systems in response to differences in soil type and water quality. PMID:27022106

  2. Experimental Warming Effects on Soil Respiration at the Temperate Boreal Forest Ecotone

    NASA Astrophysics Data System (ADS)

    Eddy, W. C.; Hobbie, S. E.; Reich, P. B.; Rich, R. L.; Montgomery, R. A.; Oleksyn, J.

    2010-12-01

    Climate models project that global mean annual temperature will increase by 1.1-6.4°C by the end of the 21st century. Whether terrestrial ecosystem feedbacks will mitigate or enhance warming represents a significant uncertainty in such projections of future climate. One of the largest potential positive feedbacks to climate warming is that arising from enhanced release of CO2 from warmer soils. Soils contain approximately twice as much carbon (C) as the atmosphere and microbial decomposition of soil C is expected to increase with climate warming, as temperature is often the most important factor in determining rates of soil organic matter decomposition. Thus, the aim of this investigation is to determine the soil respiration response to warming in a highly replicated open-air ecosystem warming experiment in two southern boreal forests of Minnesota. We measured in situ soil respiration response to ecosystem warming in an open-air warming experiment at two southern boreal forest sites in northern Minnesota. The experiment uses infrared heat lamps and soil heating cables (at 10-cm depth) to heat 7-m2 plots continuously by during the growing season by 2 or 4°C above ambient. Additionally, there are two ambient temperature treatments, one undisturbed, and the other with inactive soil warming cables (n=6). We measured soil CO2 flux every two weeks during the snow free season for two growing seasons (2009-2010) using a portable infrared gas analyzer with soil chamber attached. To date, we found slight increases in soil respiration in the two heated treatments relative to the disturbed soil control, corresponding to a 13% (2009) and 14% (2010) increase in soil CO2 flux in the +4°C treatment. These treatment effects are smaller than initial warming effects on soil respiration in many other studies. Several untested mechanisms could explain the smaller than expected warming effects on soil respiration. One likely explanation is that warming has significantly reduced soil

  3. Species identities, not functional groups, explain the effects of earthworms on litter carbon-derived soil respiration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil respiration is frequently measured as a surrogate for biological activities and is important in soil carbon cycling. The heterotrophic component of soil respiration is primarily driven by microbial decomposition of leaf litter and soil organic matter, and is partially controlled by resource ava...

  4. The responses of soil respiration to nitrogen addition in a temperate grassland in northern China.

    PubMed

    Luo, Qinpu; Gong, Jirui; Zhai, Zhanwei; Pan, Yan; Liu, Min; Xu, Sha; Wang, Yihui; Yang, Lili; Baoyin, Taoge-Tao

    2016-11-01

    Anthropogenic activities have increased nitrogen (N) inputs to grassland ecosystems. Knowledge of the impact of soil N availability on soil respiration (RS) is critical to understand soil carbon balances and their responses to global climate change. A 2-year field experiment was conducted to evaluate the response of RS to soil mineral N in a temperate grassland in northern China. RS, abiotic and biotic factors, and N mineralization were measured in the grassland, at rates of N addition ranging from 0 to 25gNm(-2)yr(-1). Annual and dormant-season RS ranged from 241.34 to 283.64g C m(-2) and from 61.34 to 83.84g C m(-2) respectively. High N application significantly increased RS, possibly due to increased root biomass and increased microbial biomass. High N treatment significantly increased soil NO3-N and inorganic N content compared with the control. The ratio of NO3-N to NH4-N and the N mineralization rate were significantly positively correlated with RS, but NH4-N was not correlated or negatively correlated with RS during the growing season. The temperature sensitivity of RS (Q10) was not significantly affected by N levels, and ranged from 1.90 to 2.20, but decreased marginally significantly at high N. RS outside the growing season is an important component of annual RS, accounting for 25.0 to 29.6% of the total. High N application indirectly stimulated RS by increasing soil NO3-N and net nitrification, thereby eliminating soil N limitations, promoting ecosystem productivity, and increasing soil CO2 efflux. Our results show the importance of distinguishing between NO3-N and NH4-N, as their impact on soil CO2 efflux differed.

  5. The responses of soil respiration to nitrogen addition in a temperate grassland in northern China.

    PubMed

    Luo, Qinpu; Gong, Jirui; Zhai, Zhanwei; Pan, Yan; Liu, Min; Xu, Sha; Wang, Yihui; Yang, Lili; Baoyin, Taoge-Tao

    2016-11-01

    Anthropogenic activities have increased nitrogen (N) inputs to grassland ecosystems. Knowledge of the impact of soil N availability on soil respiration (RS) is critical to understand soil carbon balances and their responses to global climate change. A 2-year field experiment was conducted to evaluate the response of RS to soil mineral N in a temperate grassland in northern China. RS, abiotic and biotic factors, and N mineralization were measured in the grassland, at rates of N addition ranging from 0 to 25gNm(-2)yr(-1). Annual and dormant-season RS ranged from 241.34 to 283.64g C m(-2) and from 61.34 to 83.84g C m(-2) respectively. High N application significantly increased RS, possibly due to increased root biomass and increased microbial biomass. High N treatment significantly increased soil NO3-N and inorganic N content compared with the control. The ratio of NO3-N to NH4-N and the N mineralization rate were significantly positively correlated with RS, but NH4-N was not correlated or negatively correlated with RS during the growing season. The temperature sensitivity of RS (Q10) was not significantly affected by N levels, and ranged from 1.90 to 2.20, but decreased marginally significantly at high N. RS outside the growing season is an important component of annual RS, accounting for 25.0 to 29.6% of the total. High N application indirectly stimulated RS by increasing soil NO3-N and net nitrification, thereby eliminating soil N limitations, promoting ecosystem productivity, and increasing soil CO2 efflux. Our results show the importance of distinguishing between NO3-N and NH4-N, as their impact on soil CO2 efflux differed. PMID:27396319

  6. Soil water repellency affects production and transport of CO2 and CH4 in soil

    NASA Astrophysics Data System (ADS)

    Urbanek, Emilia; Qassem, Khalid

    2016-04-01

    Soil moisture is known to be vital in controlling both the production and transport of C gases in soil. Water availability regulates the decomposition rates of soil organic matter by the microorganisms, while the proportion of water/air filled pores controls the transport of gases within the soil and at the soil-atmosphere interface. Many experimental studies and process models looking at soil C gas fluxes assume that soil water is uniformly distributed and soil is easily wettable. Most soils, however, exhibit some degree of soil water repellency (i.e. hydrophobicity) and do not wet spontaneously when dry or moderately moist. They have restricted infiltration and conductivity of water, which also results in extremely heterogeneous soil water distribution. This is a world-wide occurring phenomenon which is particularly common under permanent vegetation e.g. forest, grass and shrub vegetation. This study investigates the effect of soil water repellency on microbial respiration, CO2 transport within the soil and C gas fluxes between the soil and the atmosphere. The results from the field monitoring and laboratory experiments show that soil water repellency results in non-uniform water distribution in the soil which affects the CO2 and CH4 gas fluxes. The main conclusion from the study is that water repellency not only affects the water relations in the soil, but has also a great impact on greenhouse gas production and transport and therefore should be included as an important parameter during the sites monitoring and modelling of gas fluxes.

  7. Soil respiration from a boreal forest fire scar chronosequence

    NASA Astrophysics Data System (ADS)

    Smith, D.; Kaduk, J.; Balzter, H.; Wooster, M.; Mottram, G.

    2007-12-01

    Climate change predictions suggest that warming is to be most pronounced at high latitudes, with a possibility of boreal forest warming of 4-6°C in the next 50-100 years. This has lead to the suggestion that changes in boreal forest soil carbon (C) storage could significantly alter the global soil C balance. Fire is the most significant factor controlling succession in the boreal forest biome and it is possible that climate change will lead to an increase in fire regime e.g. size, frequency, intensity, or any combination of these. Our research is investigating C flux dynamics in a Canadian boreal forest jack pine (Pinus banksiana Lamb.) dominated fire scar chronosequence. Fieldwork is carried out at Sharpsand Creek experimental burn site, near Thessalon, Ontario, Canada, where there are numerous fire scars of different ages. In June 2006 soil respiration (Rs), soil temperature (Ts) and soil moisture (Ms) were measured on three replicate scars selected from plot last burnt in 1948 and 1991. Rs values were later adjusted for Ts using a Q10 value of 2. There was no significant difference in mean adjusted Rs between the two scar age categories. It is likely that sample sizes were not large enough here to detect significant differences. In May 2007, large areas of the field site burnt as a result of wildfire; this provided an opportunity to take a large number of Rs measurements from recently burnt fire scars, as well as from those areas unaffected by the burn. Rs, Ts and Ms measurements were taken from 1948, 1975 and 1991 scar age categories (three replicate scars each) that were burnt in 2007, as well as a 1948 and 1991 fire scar that was unaffected by the wildfire. Soil samples were taken from three locations per fire scar surveyed and analysed in the laboratory for total C content. There was a significant difference in mean Rs adjusted for Ts and Ms (Rsadj) between the three pre-2007 fire scar age categories 1948, 1975 and 1991, that were all burnt in 2007. Mean

  8. Soil CO2 constrain and distinction of root respiration and microbial activity by soil CO2 and CH4 profile

    NASA Astrophysics Data System (ADS)

    Ji, S.; Breecker, D.; Nie, J.

    2015-12-01

    Profiles of soil pore space CO2 and CH4 concentrations are rarely reported, especially from the same soils, yet are important for a number of applications. First, quantifying the component of respired CO2 in the soil pore spaces improves paleosol-based paleo-atmospheric CO2 estimates. Second, profiles can be used to estimate the average depth of biological activity (e.g. respiration and CH4 oxidation). Third, CH4 profiles, by identifying microbial activity, may help distinguish root/rhizosphere respiration from microbial decomposition. Here, we report soil CO2 and CH4 profiles measured at the Semi-Arid Climate Observatory and Laboratory (SACOL) on the Chinese Loess Plateau (CLP) at Lanzhou University, Gansu, China. Soil parent material on the site is mainly Quaternary aeolian loess and classifies as an Entisol. Soil respired CO2 (S(z) = soil CO2 - atmospheric CO2) is the most uncertain variable required to reconstruct ancient atmospheric CO2 concentrations from paleosol carbonates. Our direct soil pore space CO2 measurements show that S(z) values varied from ~100ppmV during the spring to ~2200ppmV during the summer. S(z) average 390 ± 30ppmV during May before the summer monsoon begins when soil temperature is increasing, soil water content is at a minimum and pedogenic carbonate may be forming. This value lies in the range of S(z) values previously estimated for surface Inceptisols (300 ± 100ppmV, Breecker 2013) and is lower than Pleistocene CLP paleosols (Da et al.,2015) in similar parent material. Our direct measurements of soil pore space CO2 thus support these previous independent S(z) estimates. We also investigate the average depth of CH4 oxidation and soil respiration, which range from 3-10cm and at least 20cm, respectively, using the shapes of soil gas profiles. Fitting observed soil CO2 and CH4 profiles with a production-diffusion model show that the average depth of CH4 oxidation was always at least 10 cm shallower than the average depth of respiration

  9. [Variation of soil respiration and its underlying mechanism in grasslands of northern China].

    PubMed

    Hou, Jian-Feng; Lü, Xiao-Tao; Wang, Chao; Wang, Peng

    2014-10-01

    Soil respiration is one of the most important variables in terrestrial ecosystem progresses and global carbon cycle, and determines the CO2 flux from soil to atmosphere. Soil respiration also has great implications for predicting regional and even global carbon cycle changes under the background of global climate change. We measured respiration rates of soil samples collected from northern China grassland transect by short term incubation experiment in laboratory. Results showed that soil respiration rates increased with mean annual precipitation (MAP) from west sites to east sites, ranging from 0.35 to 2.09 μg CO2-C · g(-1) · h(-1). The variation range of soil respiration rates were 0.35-0.73 μg CO2-C · g(-1) · h(-1) with MAP < 100 mm, 0.57-0.98 μg CO2-C · g(-1) · h(-1) with MAP between 100 mm and 200 mm and 0.83-2.10 μg CO2-C · g(-1) · h(-1) with MAP > 300 mm, respectively. Soil respiration had a significant positive relationship with MAP, aboveground biomass, soil organic carbon and nitrogen content, while had a negative relationship with mean annual temperature and soil pH. Analysis of boosted regression tree showed that the predictors accounted for the explained variation included MAP (25.5%), aboveground biomass (23.6%), soil organic carbon content (18.3%) and soil organic nitrogen content (12.5%), and soil pH and mean annual tem- perature only explained 10.8% and 9.2% of the total variation, respectively.

  10. [Soil biochemical characteristics in different ecological systems and their relationships with soil respiration and N2O emission].

    PubMed

    Chen, Ling; Fan, Hui; Jiang, Jing-Yan

    2014-08-01

    The biochemical characteristics of soil in different ecological system and their effects on soil respiration (CO2) and nitrous oxide (N2O) emission were investigated by an indoor incubation method. The results showed that the biochemical characteristics of soils in the different ecosystems and CO2 and N2O emissions from different soils greatly varied with each other. In general, the highest abundance of bacteria was found in the orchard soil, the highest abundance of actinomycetes occurred in the meadows and the highest abundance of fungi appeared in the woodlands. The abundance of bacteria or actinomycetes in the bamboo soil was the lowest among all soils, and the orchard soil had the lowest content of fungi. The contents of soil microbial biomass carbon and nitrogen generally followed the order of orchard soil > woodland > cropland. Moreover, cumulative CO2 and N2O emissions from the different soils followed the order of orchard soil > bamboo soil > farmland > woodland > grassland and farmland > orchard > grassland > woodland > bamboo soil, respectively. Correlation analysis indicated that there was positive correlations between the abundance of soil bacteria and the contents of microbial biomass carbon and nitrogen, as well as between the abundance of soil fungi and the soil total nitrogen content (P < 0.05), while the abundance of soil actinomycosis was positively correlated with soil organic carbon and total nitrogen contents (P < 0.01). The soil bacteria, microbial carbon and nitrogen had a significant positive impact on soil respiration (P < 0.05), and soil bacteria, actinomycetes, fungi and ammonium nitrogen had the same impact on N2O emissions (P < 0.05). Stepwise regression analysis suggested that soil respiration could be quantitatively determined by a linear combination of soil bacteria and soil pH, while N2O emission was mainly dependent on the values of soil bacteria and ammonium nitrogen.

  11. Estimated soil respiration rates decreased with long-term soil microclimate changes in successional forests in southern China.

    PubMed

    Huang, Yuhui; Zhou, Guoyi; Tang, Xuli; Jiang, Hao; Zhang, Deqiang; Zhang, Qianmei

    2011-12-01

    The response of soil respiration to short-term environmental factors changes has been well studied, whereas the influences of long-term soil microclimate changes on soil respiration are still highly unclear, especially in tropical ecosystems. We hypothesized that soil carbon accumulation in southern China, especially in mature forest during recent years, partly resulted from reducing soil respiration rates. To test this hypothesis, we analyzed the temporal trends and variations of air temperature, soil temperature and soil water content (hereafter referred to as SWC), and then estimated soil respiration rates in the 1980s and 2000s with soil temperature and SWC by regression model in three subtropical forests which are at early-, mid-, and advanced-successional stages, respectively, in Dinghushan Nature Reserve (hereafter referred to as DNR) in southern China. The annual mean ambient air temperature increased by 1.03 ± 0.15°C in the last 50 years (1954-2007) in DNR. Rainfall amount in the corresponding period did not change significantly, but rainfall pattern changed remarkably in the last three decades (1978-2007). Soil temperature is correlated with ambient air temperature. The average SWC was 36.8 ± 8.4%, 34.7 ± 8.1% and 29.6 ± 8.1% in the 1980s, and then dropped sharply to 23.6 ± 2.9%, 20.5 ± 4.2% and 17.6 ± 3.9% in the 2000s, for the advanced, mid- and early-successional forests, respectively. Concurrent changes of soil temperature and SWC may have a negative effect on soil respiration rates for all three forests, implicated that soil respiration may have a negative feedback to regional climate change and carbon could be sequestered in subtropical forests in southern China. PMID:21983997

  12. Influence of Snow Cover Duration on Soil Evaporation and Respiration Efflux in Mixed-conifer Ecosystems

    NASA Astrophysics Data System (ADS)

    Nelson, K.; Papuga, S. A.; John, G. P.; Minor, R.; Barron-Gafford, G. A.

    2011-12-01

    Subalpine mixed-conifer ecosystems are sensitive to a warming climate and are dependent on snowfall, which is expected to decrease under projected climate change. These changes in snowpack are likely to have important consequences for water and carbon cycling in these ecosystems and those downstream in the watersheds. Particularly within the semiarid southwest, such transitions to a drier and warmer environment will directly influence localized water and carbon dynamics and indirectly influence regional-scale levels of water availability and carbon sequestration. Therefore, in this study we monitored soil evaporation and respiration to evaluate how snow accumulation and duration of snow cover affected these effluxes. Our study took place within a mixed-conifer ecosystem within the Santa Catalina Mountains about 10 km north of Tucson, Arizona. Here, three understory time-lapse digital cameras have monitored snow cover within the footprint of an eddy covariance tower for nearly two years. Using these cameras, we identified locations with short and long snow duration. We then placed 6 soil collars (3 in short snow duration; 3 in long snow duration) within the field of view of each camera. Since July 2010, evaporation and soil respiration data have been collected regularly from these collars; soil temperature and soil moisture measurements were also collected. Our primary findings include: (1) evaporation fluxes do not vary drastically between long and short snow season sites, (2) evaporation fluxes for both short and long snow seasons have a strong relationship with soil moisture and a poor relationship with soil temperature, (3) CO2 fluxes vary noticeably between long and short snow season sites throughout the year, with short snow season fluxes typically higher than those of long snow season sites, and (4) CO2 fluxes for short and long snow seasons have a strong relationship with soil temperature and a poor relationship with soil moisture. Our findings suggest that

  13. [Soil respiration and carbon balance in wheat field under conservation tillage].

    PubMed

    Zhang, Sai; Wang, Long-Chang; Huang, Zhao-Cun; Jia, Hui-Juan; Ran, Chun-Yan

    2014-06-01

    In order to study the characteristics of carbon sources and sinks in the winter wheat farmland ecosystem in southwest hilly region of China, the LI6400-09 respiratory chamber was adopted in the experiment conducted in the experimental field in Southwest University in Chongqing. The soil respiration and plant growth dynamics were analyzed during the growth period of wheat in the triple intercropping system of wheat-maize-soybean. Four treatments including T (traditional tillage), R (ridge tillage), TS (traditional tillage + straw mulching), and RS (ridge tillage + straw mulching) were designed. Root biomass regression (RR) and root exclusion (RE) were used to compare the contribution of root respiration to total soil respiration. The results showed that the average soil respiration rate was 1.71 micromol x (m2 x s)(-1) with a variation of 0.62-2.91 micromol x (m2 x s)(-1). Significant differences in soil respiration rate were detected among different treatments. The average soil respiration rate of T, R, TS and RS were 1.29, 1.59, 1.99 and 1.96 micromol x (m2 x s)(-1), respectively. R treatment did not increase the soil respiration rate significantly until the jointing stage. Straw mulching treatment significantly increased soil respiration, with a steadily high rate during the whole growth period. During the 169 days of growth, the total soil respiration was 2 266.82, 2799.52, 3 483.73 and 3 443.89 kg x hm(-2) while the cumulative aboveground biomasses were 51 800.84, 59 563.20, 66 015.37 and 7 1331.63 kg x hm(-2). Compared with the control, the yield of R, TS and RS increased by 14.99%, 27.44% and 37.70%, respectively. The contribution of root respiration to total soil respiration was 47.05% by RBR, while it was 53.97% by RE. In the early growth period, the carbon source was weak. The capacity of carbon sink started to increase at the jointing stage and reached the maximum during the filling stage. The carbon budget of wheat field was 5 924.512, 6743.807, 8350

  14. Soil organic matter content: a non-liner control on microbial respiration in soils

    NASA Astrophysics Data System (ADS)

    Schnecker, Jörg; Grandy, Stuart

    2016-04-01

    It is widely assumed that microbial activity and respiration rates respond linearly to substrate concentrations, irrespective of substrate chemical characteristics, but this assumption remains largely untested. We know that microbial decomposition of soil organic matter (SOM) and the amount of CO2 respired from soil depends on substrate availability. While soils with high SOM concentrations will have higher respiration rates than soils with low SOM concentrations, the specific relationship between substrate quantity and CO2 respired and its underlying mechanisms has robust theoretical, modeling, and management implications. In a lab incubation experiment, we amended a mixture of agricultural soil and sand with increasing amounts of one of three plant residues differing in their C/N ratio (clover C/N 14; rye C/N 23 and wheat straw C/N 110). Keeping the soil/sand mixture at a constant ratio, we obtained 9 levels of organic carbon (OC) content ranging from 0.25% to 5.7%. The sand-soil-residue mixtures were then incubated at constant temperature and water contents for a total of 63 days. Our results show that across substrates CO2 production increased with increasing OC content following a sigmoidal curve function instead of the expected linear one. A breakpoint analysis for the respiration curve of rye revealed two significant break points at 1.3 and 3.8 % OC. The three individual linear relations might be shaped by spatial separation of substrate and microbes and the interaction of the microbes themselves. In the first "survival" phase up to 1.3 % OC, more substrate leads to the survival of more microbes. However, microbial growth does not result in the discovery of new resources. In the "expansion" phase (1.3 % OC to 3.8 % OC), microbial growth is successful and microbes can exploit new resources. Finally, in the "competition" phase microbes start to compete for space and resources, which leads to a decrease in decomposition and respiration. While the results for

  15. [Effects of conversion of natural broad-leaved forest to Chinese fir plantation on soil respiration in subtropical China].

    PubMed

    Zhang, Rui; Bai, Yang; Liu, Juan; Jiang, Pei-kun; Zhou, Guo-mo; Wu, Jia-sen; Tong, Zhi-peng; Li, Yong-fu

    2015-10-01

    Soil CO2 effluxes in natural broad-leaved forest and the conversed Chinese fir plantation in Linglong Mountains Scenic of Zhejiang Province were evaluated by using static closed chamber and gas chromatography method. The results showed that soil CO2 efflux showed consistent seasonal dynamics in natural broad-leaved forest and Chinese fir plantation, with the maximums observed in summer and autumn, the minimums in winter and spring. Soil CO2 effluxes were 20.0-111.3 and 4.1-118.6 mg C . m-2 . h-1 in natural broad-leaved forest and Chinese fir plantation, respectively. The cumulative soil CO2 emission of natural broad-leaved forest (16.46 t CO2 . hm-2 . a-1) was significantly higher than that of Chinese fir plantation (11.99 t CO2 . hm-2 . a-1). Soil moisture did not affect soil CO2 efflux. There was a significant relationship between soil CO2 efflux and soil temperature at 5 cm depth. There was no significant relationship between soil CO2 efflux of natural broad-leaved forest and water soluble organic carbon content, while water soluble organic carbon content affected significantly soil CO2 efflux in Chinese fir plantation. Converting the natural broad-leaved forest to Chinese fir plantation reduced soil CO2 efflux significantly but improved the sensitivity of soil respiration to environmental factors. PMID:26995901

  16. Effects of soil moisture on the temperature sensitivity of soil heterotrophic respiration: a laboratory incubation study.

    PubMed

    Zhou, Weiping; Hui, Dafeng; Shen, Weijun

    2014-01-01

    The temperature sensitivity (Q10) of soil heterotrophic respiration (Rh) is an important ecological model parameter and may vary with temperature and moisture. While Q10 generally decreases with increasing temperature, the moisture effects on Q10 have been controversial. To address this, we conducted a 90-day laboratory incubation experiment using a subtropical forest soil with a full factorial combination of five moisture levels (20%, 40%, 60%, 80%, and 100% water holding capacity--WHC) and five temperature levels (10, 17, 24, 31, and 38°C). Under each moisture treatment, Rh was measured several times for each temperature treatment to derive Q10 based on the exponential relationships between Rh and temperature. Microbial biomass carbon (MBC), microbial community structure and soil nutrients were also measured several times to detect their potential contributions to the moisture-induced Q10 variation. We found that Q10 was significantly lower at lower moisture levels (60%, 40% and 20% WHC) than at higher moisture level (80% WHC) during the early stage of the incubation, but became significantly higher at 20%WHC than at 60% WHC and not significantly different from the other three moisture levels during the late stage of incubation. In contrast, soil Rh had the highest value at 60% WHC and the lowest at 20% WHC throughout the whole incubation period. Variations of Q10 were significantly associated with MBC during the early stages of incubation, but with the fungi-to-bacteria ratio during the later stages, suggesting that changes in microbial biomass and community structure are related to the moisture-induced Q10 changes. This study implies that global warming's impacts on soil CO2 emission may depend upon soil moisture conditions. With the same temperature rise, wetter soils may emit more CO2 into the atmosphere via heterotrophic respiration. PMID:24647610

  17. Effects of soil moisture on the temperature sensitivity of soil heterotrophic respiration: a laboratory incubation study.

    PubMed

    Zhou, Weiping; Hui, Dafeng; Shen, Weijun

    2014-01-01

    The temperature sensitivity (Q10) of soil heterotrophic respiration (Rh) is an important ecological model parameter and may vary with temperature and moisture. While Q10 generally decreases with increasing temperature, the moisture effects on Q10 have been controversial. To address this, we conducted a 90-day laboratory incubation experiment using a subtropical forest soil with a full factorial combination of five moisture levels (20%, 40%, 60%, 80%, and 100% water holding capacity--WHC) and five temperature levels (10, 17, 24, 31, and 38°C). Under each moisture treatment, Rh was measured several times for each temperature treatment to derive Q10 based on the exponential relationships between Rh and temperature. Microbial biomass carbon (MBC), microbial community structure and soil nutrients were also measured several times to detect their potential contributions to the moisture-induced Q10 variation. We found that Q10 was significantly lower at lower moisture levels (60%, 40% and 20% WHC) than at higher moisture level (80% WHC) during the early stage of the incubation, but became significantly higher at 20%WHC than at 60% WHC and not significantly different from the other three moisture levels during the late stage of incubation. In contrast, soil Rh had the highest value at 60% WHC and the lowest at 20% WHC throughout the whole incubation period. Variations of Q10 were significantly associated with MBC during the early stages of incubation, but with the fungi-to-bacteria ratio during the later stages, suggesting that changes in microbial biomass and community structure are related to the moisture-induced Q10 changes. This study implies that global warming's impacts on soil CO2 emission may depend upon soil moisture conditions. With the same temperature rise, wetter soils may emit more CO2 into the atmosphere via heterotrophic respiration.

  18. Effects of Soil Moisture on the Temperature Sensitivity of Soil Heterotrophic Respiration: A Laboratory Incubation Study

    PubMed Central

    Zhou, Weiping; Hui, Dafeng; Shen, Weijun

    2014-01-01

    The temperature sensitivity (Q10) of soil heterotrophic respiration (Rh) is an important ecological model parameter and may vary with temperature and moisture. While Q10 generally decreases with increasing temperature, the moisture effects on Q10 have been controversial. To address this, we conducted a 90-day laboratory incubation experiment using a subtropical forest soil with a full factorial combination of five moisture levels (20%, 40%, 60%, 80%, and 100% water holding capacity - WHC) and five temperature levels (10, 17, 24, 31, and 38°C). Under each moisture treatment, Rh was measured several times for each temperature treatment to derive Q10 based on the exponential relationships between Rh and temperature. Microbial biomass carbon (MBC), microbial community structure and soil nutrients were also measured several times to detect their potential contributions to the moisture-induced Q10 variation. We found that Q10 was significantly lower at lower moisture levels (60%, 40% and 20% WHC) than at higher moisture level (80% WHC) during the early stage of the incubation, but became significantly higher at 20%WHC than at 60% WHC and not significantly different from the other three moisture levels during the late stage of incubation. In contrast, soil Rh had the highest value at 60% WHC and the lowest at 20% WHC throughout the whole incubation period. Variations of Q10 were significantly associated with MBC during the early stages of incubation, but with the fungi-to-bacteria ratio during the later stages, suggesting that changes in microbial biomass and community structure are related to the moisture-induced Q10 changes. This study implies that global warming’s impacts on soil CO2 emission may depend upon soil moisture conditions. With the same temperature rise, wetter soils may emit more CO2 into the atmosphere via heterotrophic respiration. PMID:24647610

  19. Partitioning sources of soil-respired CO2 and their seasonal variation using a unique radiocarbon tracer

    SciTech Connect

    Cisneros-Dozal, Luz Maria; Trumbore, Susan E.; Hanson, Paul J

    2006-01-01

    Soil respiration is derived from heterotrophic (decomposition of soil organic matter) and autotrophic (root/rhizosphere respiration) sources, but there is considerable uncertainty about what factors control variations in their relative contributions in space and time. We took advantage of a unique whole-ecosystem radiocarbon label in a temperate forest to partition soil respiration into three sources: (1) recently photosynthesized carbon (C), which dominates root and rhizosphere respiration; (2) leaf litter decomposition and (3) decomposition of root litter and soil organic matter 41-2 years old. Heterotrophic sources and specifically leaf litter decomposition were large contributors to total soil respiration during the growing season. Relative contributions from leaf litter decomposition ranged from a low of 1 3% of total soil respiration (63 mgCm 2 h 1) when leaf litter was extremely dry, to a high of 42 16% (96 38mgCm 2 h 1). Total soil respiration fluxes varied with the strength of the leaf litter decomposition source, indicating that moisture-dependent changes in litter decomposition drive variability in total soil respiration fluxes. In the surface mineral soil layer, decomposition of C fixed in the original labeling event (3-5 years earlier) dominated the isotopic signature of heterotrophic respiration. Root/rhizosphere respiration accounted for 16 10% to 64 22% of total soil respiration, with highest relative contributions coinciding with low overall soil respiration fluxes. In contrast to leaf litter decomposition, root respiration fluxes did not exhibit marked temporal variation ranging from 34 14 to 40 16mgCm 2 h 1 at different times in the growing season with a single exception (88 35 mgCm 2 h 1). Radiocarbon signatures of root respired CO2 changed markedly between early and late spring (March vs. May), suggesting a switch from stored nonstructural carbohydrate sources to more recent photosynthetic products.

  20. Variation in Soil Respiration across Soil and Vegetation Types in an Alpine Valley

    PubMed Central

    Rubin, Aurélie

    2016-01-01

    Background and Aims Soils of mountain regions and their associated plant communities are highly diverse over short spatial scales due to the heterogeneity of geological substrates and highly dynamic geomorphic processes. The consequences of this heterogeneity for biogeochemical transfers, however, remain poorly documented. The objective of this study was to quantify the variability of soil-surface carbon dioxide efflux, known as soil respiration (Rs), across soil and vegetation types in an Alpine valley. To this aim, we measured Rs rates during the peak and late growing season (July-October) in 48 plots located in pastoral areas of a small valley of the Swiss Alps. Findings Four herbaceous vegetation types were identified, three corresponding to different stages of primary succession (Petasition paradoxi in pioneer conditions, Seslerion in more advanced stages and Poion alpinae replacing the climactic forests), as well as one (Rumicion alpinae) corresponding to eutrophic grasslands in intensively grazed areas. Soils were developed on calcareous alluvial and colluvial fan deposits and were classified into six types including three Fluvisols grades and three Cambisols grades. Plant and soil types had a high level of co-occurrence. The strongest predictor of Rs was soil temperature, yet we detected additional explanatory power of sampling month, showing that temporal variation was not entirely reducible to variations in temperature. Vegetation and soil types were also major determinants of Rs. During the warmest month (August), Rs rates varied by over a factor three between soil and vegetation types, ranging from 2.5 μmol m-2 s-1 in pioneer environments (Petasition on Very Young Fluvisols) to 8.5 μmol m-2 s-1 in differentiated soils supporting nitrophilous species (Rumicion on Calcaric Cambisols). Conclusions Overall, this study provides quantitative estimates of spatial and temporal variability in Rs in the mountain environment, and demonstrates that estimations of

  1. Methodology for assessing respiration and cellular incorporation of radiolabeled substrates by soil microbial communities (journal version)

    SciTech Connect

    Dobbins, D.C.; Pfaender, F.K.

    1988-01-01

    A method is described for determining biodegradation kinetics of both naturally occurring and xenobiotic compounds in surface and subsurface soil samples. The method measures both respiration and uptake into cellular biomass of 14C-labeled substrates. After separation of the cells and the soil particles by centrifugation, the cells were trapped on membrane filters for liquid scintillation counting. Mass balances were easily obtained. The technique was used to measure metabolic activity in soil profiles, including unsaturated and saturated zones. First-order rate constants were determined for amino acid metabolism and for m-cresol metabolism. Saturation kinetics were observed for amino acids and m-cresol. m-Cresol values for uptake often exceeded those for respiration by greater than a factor of ten. Saturation was not observed in many horizons. Frequently, respiration obeyed saturation kinetics, whereas uptake was first order. It is concluded that measuring only kinetics of respiration may lead to severe underestimations of biodegradation rates.

  2. [Effect of grazing on the temperature sensitivity of soil respiration in Hulunber meadow steppe].

    PubMed

    Wang, Xu; Yan, Rui-Rui; Deng, Yu; Yan, Yu-Chun; Xin, Xiao-Ping

    2014-05-01

    Grazing is one of the major human activities which lead to disturbance on grassland ecosystem. Quantifying the effect of grazing on the temperature sensitivity of soil respiration ( Q10 ) is essential for accurate assessment of carbon budget in grassland ecosystem. This study was conducted on the grazing gradients experiment platform in Hulunber meadow steppe. Soil respiration was measured by a dynamic closed chamber method (equipped with Li 6400-09, Lincoln, NE, USA) during the growing season in 2011. The results showed that soil respiration had significant seasonal variation and the maximum occurred in July, which was mainly dominated by temperature. The order of average soil respiration during the period from May to September in different treatments was G1 > GO > G2 > G3 > G4 > G5. Comparing with non-grazing treatment, Q10 under heavy grazing conditions (0. 92 Au hm-2) was reduced by about 10% , and was increased a little under light grazing conditions (0. 23 Au hm-2). There was a significant negative correlation between Q15 and grazing intensities (r = 0. 944, P <0. 05) . Grazing could decrease the temperature sensitivity of soil respiration to different degrees. The Q10 under different grazing gradients had positive linear regression relationships with aboveground biomass, belowground biomass, soil organic carbon and soil moisture. They could explain 71.0%-85.2% variations of Q10. It was suggested that the variation of Q10 was mainly determined by the change of biotic and environmental factors due to grazing.

  3. Effects of Spartina alterniflora invasion on soil respiration in the Yangtze River estuary, China.

    PubMed

    Bu, Naishun; Qu, Junfeng; Li, Zhaolei; Li, Gang; Zhao, Hua; Zhao, Bin; Li, Bo; Chen, Jiakuan; Fang, Changming

    2015-01-01

    Many studies have found that plant invasion can enhance soil organic carbon (SOC) pools, by increasing net primary production (NPP) and/or decreased soil respiration. While most studies have focused on C input, little attention has been paid to plant invasion effects on soil respiration, especially in wetland ecosystems. Our study examined the effects of Spartina alterniflora invasion on soil respiration and C dynamics in the Yangtze River estuary. The estuary was originally occupied by two native plant species: Phragmites australis in the high tide zone and Scirpus mariqueter in the low tide zone. Mean soil respiration rates were 185.8 and 142.3 mg CO2 m(-2) h(-1) in S. alterniflora and P. australis stands in the high tide zone, and 159.7 and 112.0 mg CO2 m(-2) h(-1) in S. alterniflora and S. mariqueter stands in the low tide zone, respectively. Aboveground NPP (ANPP), SOC, and microbial biomass were also significantly higher in the S. alterniflora stands than in the two native plant stands. S. alterniflora invasion did not significantly change soil inorganic carbon or pH. Our results indicated that enhanced ANPP by S. alterniflora exceeded invasion-induced C loss through soil respiration. This suggests that S. alterniflora invasion into the Yangtze River estuary could strengthen the net C sink of wetlands in the context of global climate change. PMID:25799512

  4. Effects of Spartina alterniflora Invasion on Soil Respiration in the Yangtze River Estuary, China

    PubMed Central

    Bu, Naishun; Qu, Junfeng; Li, Zhaolei; Li, Gang; Zhao, Hua; Zhao, Bin; Li, Bo; Chen, Jiakuan; Fang, Changming

    2015-01-01

    Many studies have found that plant invasion can enhance soil organic carbon (SOC) pools, by increasing net primary production (NPP) and/or decreased soil respiration. While most studies have focused on C input, little attention has been paid to plant invasion effects on soil respiration, especially in wetland ecosystems. Our study examined the effects of Spartina alterniflora invasion on soil respiration and C dynamics in the Yangtze River estuary. The estuary was originally occupied by two native plant species: Phragmites australis in the high tide zone and Scirpus mariqueter in the low tide zone. Mean soil respiration rates were 185.8 and 142.3 mg CO2 m−2 h−1 in S. alterniflora and P. australis stands in the high tide zone, and 159.7 and 112.0 mg CO2 m−2 h−1 in S. alterniflora and S. mariqueter stands in the low tide zone, respectively. Aboveground NPP (ANPP), SOC, and microbial biomass were also significantly higher in the S. alterniflora stands than in the two native plant stands. S. alterniflora invasion did not significantly change soil inorganic carbon or pH. Our results indicated that enhanced ANPP by S. alterniflora exceeded invasion-induced C loss through soil respiration. This suggests that S. alterniflora invasion into the Yangtze River estuary could strengthen the net C sink of wetlands in the context of global climate change. PMID:25799512

  5. Effects of Spartina alterniflora invasion on soil respiration in the Yangtze River estuary, China.

    PubMed

    Bu, Naishun; Qu, Junfeng; Li, Zhaolei; Li, Gang; Zhao, Hua; Zhao, Bin; Li, Bo; Chen, Jiakuan; Fang, Changming

    2015-01-01

    Many studies have found that plant invasion can enhance soil organic carbon (SOC) pools, by increasing net primary production (NPP) and/or decreased soil respiration. While most studies have focused on C input, little attention has been paid to plant invasion effects on soil respiration, especially in wetland ecosystems. Our study examined the effects of Spartina alterniflora invasion on soil respiration and C dynamics in the Yangtze River estuary. The estuary was originally occupied by two native plant species: Phragmites australis in the high tide zone and Scirpus mariqueter in the low tide zone. Mean soil respiration rates were 185.8 and 142.3 mg CO2 m(-2) h(-1) in S. alterniflora and P. australis stands in the high tide zone, and 159.7 and 112.0 mg CO2 m(-2) h(-1) in S. alterniflora and S. mariqueter stands in the low tide zone, respectively. Aboveground NPP (ANPP), SOC, and microbial biomass were also significantly higher in the S. alterniflora stands than in the two native plant stands. S. alterniflora invasion did not significantly change soil inorganic carbon or pH. Our results indicated that enhanced ANPP by S. alterniflora exceeded invasion-induced C loss through soil respiration. This suggests that S. alterniflora invasion into the Yangtze River estuary could strengthen the net C sink of wetlands in the context of global climate change.

  6. The Effects of Long Term Nitrogen Fertilization on Soil Respiration in Rocky Mountain National Park

    NASA Astrophysics Data System (ADS)

    Allen, J.; Denning, S.; Baron, J.

    2015-12-01

    Anthropogenic activities contribute to increased levels of nitrogen deposition and elevated CO2 concentrations in terrestrial ecosystems. The role that soils play in biogeochemical cycles is an important area of uncertainty in ecosystem ecology. One of the main reasons for this uncertainty is that we have limited understanding of belowground microbial activity and how this activity is linked to soil processes. In particular, elevated CO2 may influence soil nitrogen processes that regulate nitrogen availability to plants. Warming and nitrogen fertilization may both contribute to loss of stored carbon from mountain ecosystems, because they contribute to microbial decomposition of organic matter. To study the effects of long-term nitrogen fertilization on soil respiration, we analyzed results from a 25-year field experiment in Rocky Mountain National Park. Field treatments are in old growth Engelmann spruce forests. Soil respiration responses to the effects of nitrogen fertilization on soil carbon cycling, via respiration, were investigated during the 2013 growing season. Soil moisture, temperature, and respiration rates were measured in six 30 x 30 m plots, of the six plots three are fertilized with 25 kg N ha-1 yr-1 as ammonium nitrate (NH4NO3) pellets and three receives ambient atmospheric nitrogen deposition (1-6 kg N/ha/yr) in Rocky Mountain National Park. We found that respirations rates in the fertilized plots were not significantly higher than respiration rates in the unfertilized plots. We speculate that acclimation to long-term fertilization and relatively high levels of nitrogen deposition in the control plots both contribute to the insensitivity of soil respiration to fertilization at this site.

  7. [Effects of compaction on diurnal variaaton of soil respiration in Larix gmellini plantation in summer].

    PubMed

    He, Na; Wang, Li-hai

    2010-12-01

    Taking the Larix gmellinii plantation in the experimental forest farm of Northeast Forestry University as test object, and by using Li-8100 automatic instrument, the daily CO2 emission rate of soil in summer under different degrees of man-made compaction was measured, with the regression models established. There were significant differences in the diurnal variation of soil respiration rate under different degrees of man-made compaction. In CK (no compaction), the maximum value of soil respiration appeared at 15:30-17:30, and the minimum value appeared at 03:30-05:30, which were obviously lagged behind those in compaction treatments. The maximum and minimum values of soil respiration rate in main roads appeared at 09:30-11:30 and 23:30-01:30, and those in branch roads appeared at 11:30 and 01:30-03:30, respectively. In all treatments, soil respiration rate had significant correlations with surface temperature, relative humidity, and the temperature at 10 cm soil depth, but the correlation with the soil moisture at 5 cm depth tended to be not significant when the compaction degree was increasing. Compaction altered surface soil physical structure, decreased surface soil CO2 release rate. PMID:21442991

  8. Soil Respiration Declines Following Beetle - Induced Forest Mortality in a Lodgepole Pine Forest

    NASA Astrophysics Data System (ADS)

    Borkhuu, B.; Peckham, S. D.; Norton, U.; Ewers, B. E.; Pendall, E.

    2014-12-01

    Lodgepole pine (Pinus contorta var. latifolia) forests in northern Colorado and southeast Wyoming have been undergoing a major mortality event owing to mountain pine beetle (Dendroctonus ponderosae) infestation since 2007. We studied biotic and abiotic drivers of growing season soil respiration in four mature stands experiencing different levels of mortality between 2008 and 2012 in the Medicine Bow Mountains, southeastern Wyoming, USA. For five years, beetle infestation significantly altered forest structure. Stand mortality was 30% and more than 80% in stands with the lowest and highest mortality, respectively. Understory vegetation cover increased by 50% for five years following beetle infestation. Needlefall was increased by more than 50% during first two years of beetle infestation compared to the pre-disturbance period. We did not observe an immediate increase in soil respiration following beetle infestation as suggested by some researchers. Soil respiration rates in midsummer ranged from 1.4 ± 0.1 μmol m-2 s-1 in stands with highest mortality to 3.1 ± 0.2 μmol m-2s-1 in uninfested stand. Live tree basal area was the dominant factor controlling soil respiration, explaining more than 60% of the interannual and spatial variations in response to the disturbance. In addition, soil respiration was significantly correlated with fine root biomass, which explained 55% of variations, providing strong evidence that autotrophic respiration dominated the forest soil respiration flux. Furthermore, the seasonality of soil respiration was controlled mainly by mean monthly precipitation and mid-day photosynthetically active radiation. Each factor predicted from 30% to 50% of seasonal soil respiration variability with the highest correlation coefficients in stand with the lowest mortality. Our results clearly indicate that the reduction of photosynthesis in trees over the infestation period significantly reduced soil respiration. The remaining activity in dead stands may

  9. Microbial respiration and organic carbon indicate nutrient cycling recovery in reclaimed soils

    SciTech Connect

    Ingram, L.J.; Schuman, G.E.; Stahl, P.D.; Spackman, L.K.

    2005-12-01

    Soil quality and the ability of soil to sustain nutrient cycling in drastically disturbed ecosystems will influence the establishment and maintenance of a permanent and stable plant community. We undertook research to evaluate a recently developed method to assess soil quality and nutrient cycling potential in a series of reclaimed soils. The method involves correlating the 3-d flush of microbial respiration after a soil is rewetted against a range of soil biological parameters. Soils were sampled from a number of reclaimed coal mines, a reclaimed uranium mine, and native, undisturbed prairie. All sites were located in semiarid Wyoming.

  10. Influence of Soil Moisture on Litter Respiration in the Semiarid Loess Plateau

    PubMed Central

    Zhang, Yanjun; Guo, Shengli; Liu, Qingfang; Jiang, Jishao

    2014-01-01

    Understanding the response mechanisms of litter respiration to soil moisture in water-limited semi-arid regions is of vital importance to better understanding the interplay between ecological processes and the local carbon cycle. In situ soil respiration was monitored during 2010–2012 under various conditions (normal litter, no litter, and double litter treatments) in a 30-year-old artificial black locust plantation (Robinia pseudoacacia L.) on the Loess Plateau. Litter respiration with normal and double litter treatments exhibited similar seasonal variation, with the maximum value obtained in summer (0.57 and 1.51 μmol m−2 s−1 under normal and double litter conditions, respectively) and the minimum in spring (0.27 and 0.69 μmol m−2 s−1 under normal and double litter conditions, respectively). On average, annual cumulative litter respiration was 115 and 300 g C m−2 y−1 under normal and double litter conditions, respectively. Using a soil temperature of 17°C as the critical point, the relationship between litter respiration and soil moisture was found to follow quadratic functions well, whereas the determination coefficient was much greater at high soil temperature than at low soil temperature (33–35% vs. 22–24%). Litter respiration was significantly higher in 2010 and 2012 than in 2011 under both normal litter (132–165 g C m−2 y−1 vs. 48 g C m−2 y−1) and double litter (389–418 g C m−2 y−1 vs. 93 g C m−2 y−1) conditions. Such significant interannual variations were largely ascribed to the differences in summer rainfall. Our study demonstrates that, apart from soil temperature, moisture also has significant influence on litter respiration in semi-arid regions. PMID:25474633

  11. Soil microbial community composition and respiration along an experimental precipitation gradient in a semiarid steppe

    PubMed Central

    Zhao, Cancan; Miao, Yuan; Yu, Chengde; Zhu, Lili; Wang, Feng; Jiang, Lin; Hui, Dafeng; Wan, Shiqiang

    2016-01-01

    As a primary limiting factor in arid and semiarid regions, precipitation strongly influences soil microbial properties. However, the patterns and mechanisms of soil microbial responses to precipitation have not been well documented. In this study, changes in soil microorganisms along an experimental precipitation gradient with seven levels of precipitation manipulation (i.e., ambient precipitation as a control, and ±20%, ±40%, and ±60% of ambient precipitation) were explored in a semiarid temperate steppe in northern China. Soil microbial biomass carbon and respiration as well as the ratio of fungal to bacterial biomass varied along the experimental precipitation gradient and peaked under the +40% precipitation treatment. The shifts in microbial community composition could be largely attributable to the changes in soil water and nutrient availability. The metabolic quotient increased (indicating reduced carbon use efficiency) with increasing precipitation due to the leaching of dissolved organic carbon. The relative contributions of microbial respiration to soil and ecosystem respiration increased with increasing precipitation, suggesting that heterotrophic respiration will be more sensitive than autotrophic respiration if precipitation increases in the temperate steppe as predicted under future climate-change scenarios. PMID:27074973

  12. Comparative Assessment of the Effect of Synthetic and Natural Fungicides on Soil Respiration

    PubMed Central

    Stefani, Angelo; Felício, Joanna D’Arc; de Andréa, Mara M.

    2012-01-01

    As toxic pesticide residues may persist in agricultural soils and cause environmental pollution, research on natural fungicides to replace the synthetic compounds is currently increasing. The effect of the synthetic fungicide chlorothalonil and a natural potential fungicide on the soil microbial activity was evaluated here by the substrate-induced respiration by addition of glucose (SIR), as bioindicator in two soils (Eutrophic Humic Gley—GHE and Typic Eutroferric Chernosol—AVEC). The induced soil respiration parameter was followed during 28 days after soil treatment either with chlorathalonil (11 μg·g−1), or the methanolic fraction from Polymnia sonchifolia extraction (300 μg·g−1), and 14C-glucose (4.0 mg and 5.18 Bq of 14C-glucose g−1). The 14C-CO2 produced by the microbial respiration was trapped in NaOH (0.1 M) which was changed each two hours during the first 10 h, and 1, 3, 5, 7, 14 and 28 days after the treatments. The methanolic fraction of the plant extract inhibited (2.2%) and stimulated (1.8%) the respiration of GHE and AVEC, respectively, but the synthetic chlorothalonil caused 16.4% and 2.6% inhibition of the respiration, respectively of the GHE and AVEC soils. As the effects of the natural product were statistically small, this bioindicator indicates that the methanolic fraction of the Polymnia sonchifolia extract, which has fungicide properties, has no environmental effects. PMID:22737005

  13. Soil microbial community composition and respiration along an experimental precipitation gradient in a semiarid steppe.

    PubMed

    Zhao, Cancan; Miao, Yuan; Yu, Chengde; Zhu, Lili; Wang, Feng; Jiang, Lin; Hui, Dafeng; Wan, Shiqiang

    2016-04-14

    As a primary limiting factor in arid and semiarid regions, precipitation strongly influences soil microbial properties. However, the patterns and mechanisms of soil microbial responses to precipitation have not been well documented. In this study, changes in soil microorganisms along an experimental precipitation gradient with seven levels of precipitation manipulation (i.e., ambient precipitation as a control, and ±20%, ±40%, and ±60% of ambient precipitation) were explored in a semiarid temperate steppe in northern China. Soil microbial biomass carbon and respiration as well as the ratio of fungal to bacterial biomass varied along the experimental precipitation gradient and peaked under the +40% precipitation treatment. The shifts in microbial community composition could be largely attributable to the changes in soil water and nutrient availability. The metabolic quotient increased (indicating reduced carbon use efficiency) with increasing precipitation due to the leaching of dissolved organic carbon. The relative contributions of microbial respiration to soil and ecosystem respiration increased with increasing precipitation, suggesting that heterotrophic respiration will be more sensitive than autotrophic respiration if precipitation increases in the temperate steppe as predicted under future climate-change scenarios.

  14. An unknown respiration pathway substantially contributes to soil CO2 emissions

    NASA Astrophysics Data System (ADS)

    Maire, V.; Alvarez, G.; Colombet, J.; Comby, A.; Despinasse, R.; Dubreucq, E.; Joly, M.; Lehours, A.-C.; Perrier, V.; Shahzad, T.; Fontaine, S.

    2012-07-01

    The respiratory release of CO2 from soils is a major determinant of the global carbon cycle. It is traditionally considered that this respiration is an intracellular metabolism consisting of complex biochemical reactions carried out by numerous enzymes and co-factors. Here we show that the intracellular enzymes released from dead organisms are stabilized in soils and have access to suitable substrates and co-factors to permit function. These enzymes reconstitute an extracellular oxidative metabolism (Exomet) that may substantially contribute to soil respiration (16 to 48% of CO2 released from soils in the present study). Exomet and respiration from living organisms should be considered separately when studying effects of environmental factors on the C cycle because Exomet shows specific properties such as resistance to high temperature and toxics.

  15. Diffusive fractionation complicates isotopic partitioning of autotrophic and heterotrophic sources of soil respiration.

    PubMed

    Moyes, Andrew B; Gaines, Sarah J; Siegwolf, Rolf T W; Bowling, David R

    2010-11-01

    Carbon isotope ratios (δ¹³C) of heterotrophic and rhizospheric sources of soil respiration under deciduous trees were evaluated over two growing seasons. Fluxes and δ¹³C of soil respiratory CO₂ on trenched and untrenched plots were calculated from closed chambers, profiles of soil CO₂ mole fraction and δ¹³C and continuous open chambers. δ¹³C of respired CO₂ and bulk carbon were measured from excised leaves and roots and sieved soil cores. Large diel variations (>5‰) in δ¹³C of soil respiration were observed when diel flux variability was large relative to average daily fluxes, independent of trenching. Soil gas transport modelling supported the conclusion that diel surface flux δ¹³C variation was driven by non-steady state gas transport effects. Active roots were associated with high summertime soil respiration rates and around 1‰ enrichment in the daily average δ¹³C of the soil surface CO₂ flux. Seasonal δ¹³C variability of about 4‰ (most enriched in summer) was observed on all plots and attributed to the heterotrophic CO₂ source. PMID:20545887

  16. Response of soil respiration to experimental warming in a highland barley of the Tibet.

    PubMed

    Zhong, Zhi-Ming; Shen, Zhen-Xi; Fu, Gang

    2016-01-01

    Highland barley is an important dominant crop in the Tibet and the croplands of the Tibet are experiencing obvious climatic warming. However, information about how soil respiration will respond to climatic warming in the highland barley system is still lacking. A field warming experiment using infrared heaters with two warming magnitudes was conducted in a highland barley system of the Tibet in May 2014. Five daily cycles of soil respiration was measured using a CO2 flux system (Li-8100, Li-COR Biosciences, Lincoln, NE, USA) during the period from early June to early September in 2014. The high and low experimental warming significantly increased soil temperature by 1.98 and 1.52 °C over the whole study period, respectively. The high experimental warming significantly decreased soil moisture. Soil respiration and its temperature sensitivity did not significantly change under both the high and low experimental warming. The response of soil respiration to experimental warming did not linearly correlate with warming magnitudes because a greater experimental warming resulted in a higher soil drying. Our findings suggested that clarifying the response of soil CO2 production and its temperature sensitivity to climatic warming need consider water availability in the highland barley system of the Tibet.

  17. Soil respiration response to climate change in Pacific Northwest prairies is mediated by a regional Mediterranean climate gradient.

    PubMed

    Reynolds, Lorien L; Johnson, Bart R; Pfeifer-Meister, Laurel; Bridgham, Scott D

    2015-01-01

    Soil respiration is expected to increase with rising global temperatures but the degree of response may depend on soil moisture and other local factors. Experimental climate change studies from single sites cannot discern whether an observed response is site-dependent or generalizable. To deconvolve site-specific vs. regional climatic controls, we examined soil respiration for 18 months along a 520 km climate gradient in three Pacific Northwest, USA prairies that represents increasingly severe Mediterranean conditions from north to south. At each site we implemented a fully factorial combination of 2.5-3 °C warming and 20% added precipitation intensity. The response of soil respiration to warming was driven primarily by the latitudinal climate gradient and not site-specific factors. Warming increased respiration at all sites during months when soil moisture was not limiting. However, these gains were offset by reductions in respiration during seasonal transitions and summer drought due to lengthened periods of soil moisture limitation. The degree of this offset varied along the north-south climate gradient such that in 2011 warming increased cumulative annual soil respiration 28.6% in the northern site, 13.5% in the central site, and not at all in the southern site. Precipitation also stimulated soil respiration more frequently in the south, consistent with an increased duration of moisture limitation. The best predictors of soil respiration in nonlinear models were the Normalized Difference Vegetation Index (NDVI), antecedent soil moisture, and temperature but these models provided biased results at high and low soil respiration. NDVI was an effective integrator of climate and site differences in plant productivity in terms of their combined effects on soil respiration. Our results suggest that soil moisture limitation can offset the effect of warming on soil respiration, and that greater growing-season moisture limitation would constrain cumulative annual

  18. Ecosystem warming does not affect photosynthesis or aboveground autotrophic respiration for boreal black spruce.

    PubMed

    Bronson, Dustin R; Gower, Stith T

    2010-04-01

    We measured light-saturated photosynthesis (A(net)), foliage respiration (R(fol)) and stem respiration (R(stem)) of black spruce (Picea mariana (Mill.) B.S.P.) in heated (+5 degrees C) and control plots during 2005, 2006 and 2007 in Thompson, MB, Canada. Large greenhouses and soil-heating cables were used to maintain air and soil temperature 5 degrees C above ambient air and soil temperature. Each greenhouse contained approximately nine black spruce trees and the majority of their fine root mass. Treatments were soil and air warming, soil-only warming, greenhouses maintained at ambient air temperature and control. Gas exchange rates ranged 0.71-4.66, 0.04-0.74 and 0.1-1.0 micromol m(-)(2) s(-)(1) for A(net), R(fol) and R(stem), respectively. Treatment differences for A(net), R(fol) and R(stem) were not significant in any of the 3 years of measurements. The results of this experiment suggest that in a warmer climate, black spruce may not have significant changes in the rate of photosynthesis or respiration. PMID:20144925

  19. Response of soil respiration to soil temperature and moisture in a 50-year-old oriental arborvitae plantation in China.

    PubMed

    Yu, Xinxiao; Zha, Tianshan; Pang, Zhuo; Wu, Bin; Wang, Xiaoping; Chen, Guopeng; Li, Chunping; Cao, Jixin; Jia, Guodong; Li, Xizhi; Wu, Hailong

    2011-01-01

    China possesses large areas of plantation forests which take up great quantities of carbon. However, studies on soil respiration in these plantation forests are rather scarce and their soil carbon flux remains an uncertainty. In this study, we used an automatic chamber system to measure soil surface flux of a 50-year-old mature plantation of Platycladus orientalis at Jiufeng Mountain, Beijing, China. Mean daily soil respiration rates (R(s)) ranged from 0.09 to 4.87 µmol CO(2) m(-2) s(-1), with the highest values observed in August and the lowest in the winter months. A logistic model gave the best fit to the relationship between hourly R(s) and soil temperature (T(s)), explaining 82% of the variation in R(s) over the annual cycle. The annual total of soil respiration estimated from the logistic model was 645±5 g C m(-2) year(-1). The performance of the logistic model was poorest during periods of high soil temperature or low soil volumetric water content (VWC), which limits the model's ability to predict the seasonal dynamics of R(s). The logistic model will potentially overestimate R(s) at high T(s) and low VWC. Seasonally, R(s) increased significantly and linearly with increasing VWC in May and July, in which VWC was low. In the months from August to November, inclusive, in which VWC was not limiting, R(s) showed a positively exponential relationship with T(s). The seasonal sensitivity of soil respiration to T(s) (Q(10)) ranged from 0.76 in May to 4.38 in October. It was suggested that soil temperature was the main determinant of soil respiration when soil water was not limiting.

  20. The Significance of Diffusion Limitation for Oxygen Isotope Fractionation in Soil Respiration

    NASA Astrophysics Data System (ADS)

    Angert, A.; Luz, B.

    2001-05-01

    Oxygen concentration and its isotopic composition have been monitored in light and heavy soils. Steep oxygen gradients were present at the heavy soil site (minimal O2 concentration was 1% at 150cm depth) and delta O18 values typically ranged from 0 to -1.6 permil relative to atmospheric oxygen. In the light-soil site, the O2 concentration was 20.38% to 20.53% and delta O18 values ranged from -0.06 to 0.06 permil relative to atmospheric O2. The fractionation in soil respiration was estimated from the observed [O2] and delta O18 profiles and their change with time by a one-box analytical model and a five-box numerical model. Diffusion due to concentration and temperature gradients was taken into account. Good agreement was found between the two models, and between the model results and the measured values. The Discrimination against O18 during O2 uptake ranged from 11% to 14%, with an averaged value of 12 permil. Low discrimination (8.4-16.9 permil) was also determined in closed-system soil incubation experiments. The current understanding of the composition of air O2 attributes the magnitude of the fractionation in soil respiration to biochemical mechanisms alone. Thus the discrimination against O18 is assumed to be 18 permil in cyanide-sensitive dark respiration and 25 to 30 permil in cyanide-resistant respiration. The discrimination we report is significantly less than in dark respiration. This overall low discrimination is explained by slow diffusion in soil aggregates, and in root tissues that result in low O2 concentration in the consumption site. Since soil respiration is a major component of the global oxygen uptake this new discrimination factor should be taken into account in models of the isotopic composition of atmospheric O2.

  1. Thawing permafrost increases old soil and autotrophic respiration in tundra: partitioning ecosystem respiration using δ(13) C and ∆(14) C.

    PubMed

    Hicks Pries, Caitlin E; Schuur, Edward A G; Crummer, Kathryn G

    2013-02-01

    Ecosystem respiration (Reco ) is one of the largest terrestrial carbon (C) fluxes. The effect of climate change on Reco depends on the responses of its autotrophic and heterotrophic components. How autotrophic and heterotrophic respiration sources respond to climate change is especially important in ecosystems underlain by permafrost. Permafrost ecosystems contain vast stores of soil C (1672 Pg) and are located in northern latitudes where climate change is accelerated. Warming will cause a positive feedback to climate change if heterotrophic respiration increases without corresponding increases in primary production. We quantified the response of autotrophic and heterotrophic respiration to permafrost thaw across the 2008 and 2009 growing seasons. We partitioned Reco using Δ(14) C and δ(13) C into four sources-two autotrophic (above - and belowground plant structures) and two heterotrophic (young and old soil). We sampled the Δ(14) C and δ(13) C of sources using incubations and the Δ(14) C and δ(13) C of Reco using field measurements. We then used a Bayesian mixing model to solve for the most likely contributions of each source to Reco . Autotrophic respiration ranged from 40 to 70% of Reco and was greatest at the height of the growing season. Old soil heterotrophic respiration ranged from 6 to 18% of Reco and was greatest where permafrost thaw was deepest. Overall, growing season fluxes of autotrophic and old soil heterotrophic respiration increased as permafrost thaw deepened. Areas with greater thaw also had the greatest primary production. Warming in permafrost ecosystems therefore leads to increased plant and old soil respiration that is initially compensated by increased net primary productivity. However, barring large shifts in plant community composition, future increases in old soil respiration will likely outpace productivity, resulting in a positive feedback to climate change. PMID:23504799

  2. A comparison of trenched plot techniques for partitioning soil respiration

    SciTech Connect

    Bond-Lamberty, Benjamin; Bronson, Dustin; Bladyka, Emma; Gower, Stith T.

    2011-07-16

    Partitioning the soil surface CO{sub 2} flux (R{sub S}) flux is an important step in understanding ecosystem-level carbon cycling, given that R{sub S} is poorly constrained and its source components may have different responses to climate change. Trenched plots are a classic method of separating the R{sub S} source fluxes, but labor-intensive and may cause considerable disturbance to the soil environment. This study tested if various methods of plant suppression in trenched plots affected R{sub S} fluxes, quantified the R{sub S} response to soil temperature and moisture changes, and estimated the heterotrophic contribution to R{sub S}. It was performed in a boreal black spruce (Picea mariana) plantation, using a complete randomized design, during the 2007 growing season (May-November). Trenched plots had significantly lower R{sub S} than control plots, with differences appearing {approx}100 days after trenching; spatial variability doubled after trenching but then declined throughout the experiment. Most trenching treatments had significantly lower (by {approx}0.5 {mu}mol m{sup -2} s{sup -1}) R{sub S} than the controls, and there was no significant difference in R{sub S} among the various trenching treatments. Soil temperature at 2 cm explained more R{sub S} variability than did 10-cm temperature or soil moisture. Temperature sensitivity (Q10) declined in the control plots from {approx}2.6 (at 5 C) to {approx}1.6 (at 15 C); trenched plots values were higher, from 3.1 at 5 C to 1.9 at 15 C. We estimated R{sub S} for the study period to be 241 {+-} 40 g C m{sup -2}, with roots contributing 64% of R{sub S} after accounting for fine root decay, and 293 g C m{sup -2} for the entire year. These findings suggest that laborious hand weeding of vegetation may be usefully replaced by other methods, easing future studies of this large and poorly-understood carbon flux.

  3. Soil Organic Matter Content: A Non-linear Control on Microbial Respiration in Soils

    NASA Astrophysics Data System (ADS)

    Schnecker, J.; Grandy, S.

    2015-12-01

    Decomposition of soil organic matter (SOM) and the amount of CO2 respired from soil largely depends on the amount of substrate available to microbes. Soils with high SOM concentrations will have higher respiration rates than soils with low SOM concentrations given similar environmental conditions. It is widely assumed that microbial activity and respiration rates respond linearly to substrate concentrations. This assumption remains however largely untested. In a lab incubation experiment, we amended a mixture of agricultural soil and sand with increasing amounts of one of three plant residues differing in their C/N ratio (clover 14; rye 23 and wheat straw 110). We used 9 levels of organic carbon (OC) content ranging from 0.25% to 5.7%. The mixtures were then incubated at constant temperature and water contents for 63 days. Our results show that across substrates CO2 production increased with increasing OC content following a quadratic function instead of the expected linear one up to 2.2% OC. Above that point CO2 production leveled off and increased linearly. We hypothesize that the probability that a microbe meets a substrate also increases with increasing amounts of plant residues. At all substrate concentrations, samples amended with clover had the highest carbon losses, followed by rye and straw. Differences between the three kinds of plant residue might have been caused by their C/N ratios and thus the amount of available N. High amounts of N might have led to an increase in microbial biomass, which could occupy more space and is thus more likely to meet new substrate. Additional analysis of microbial biomass, enzyme activities and N pools will help to understand the mechanism leading to the observed CO2 patterns. A non-linear relation of CO2 production and OC content indicates that spatial separation as an inherent property of SOM content is an important control on decomposition at low OC contents. Knowledge of this controlling effect could be used to enhance

  4. Soil respiration in pits and mounds following an experimental forest blowdown

    SciTech Connect

    Millikin, C.S.; Bowden, R.D.

    1996-11-01

    Extensive uprooting of trees by windthrow can create areas of severe soil disturbance in temperate forests. Specifically, uprooted trees leave shaded pits and mounds of exposed roots and mineral soil. To assess the contribution of pit and mound microenvironments to overall soil respiration in an experimental hurricane blowdown at the Harvard Forest Long-Term Ecological Research site (MA), summer CO{sub 2} effluxes were measured on pit, mound, and undisturbed microsites. Mean CO{sub 2} effluxes were 45.4, 80.1, and 99.0 mgC m{sup -2} h{sup -1} for pit, mound, and control microsites, respectively. Although soil respiration is lower in areas of disturbed soil than in undisturbed areas, the total efflux contribution (5.3%) form pits and mounds to the overall flux rate at the site was small. The area-weighted soil respiration estimate is 3.1% lower than the estimate obtained using flux measurements from control locations alone. Measurements taken from undisturbed plots represent a small but systematic overestimate of soil respiration across the site. 25 refs., 1 fig.

  5. Soil CO2 efflux in a sand grassland: contribution by root, mycorrhizal and basal respiration components

    NASA Astrophysics Data System (ADS)

    Papp, Marianna; Balogh, János; Pintér, Krisztina; Cserhalmi, Dóra; Nagy, Zoltán

    2014-05-01

    Grasslands play an important role in global carbon cycle because of their remarkable extension and carbon storage capacity. Soil respiration takes a major part in the carbon cycle of the ecosystems; ratio of its autotrophic and heterotrophic components is important also when considering their sensitivity to environmental drivers. The aim of the study was to estimate the contribution by root, mycorrhizal and basal components to total soil CO2 efflux. The study was carried out in the semi-arid sandy grassland dominated by Festuca pseudovina at the Kiskunság National Park in Hungary (Bugac site) where C-flux measurements have been going on since 2002. The soil CO2 effluxes were measured in the following treatments: a./ control, b./ root-exclusion, c./ root and mycorrhiza exclusion by using 80 cm long 15 cm inner diameter PVC tubes and micro-pore inox meshes. Inox mesh was used to exclude roots, but let the mycorrhiza filaments to grow into the tubes. 10 soil cores were excavated, sieved, then root-free soil was packed back layer by layer into the cores giving 6 and 4 repetitions in b and c treatments respectively. Basal respiration is referred to as the heterotrophic respiration without influence of roots or mycorrhiza. Difference between root-exclusion and root and mycorrhiza exclusion treatment gave the value of mycorrhizal respiration and control (non-disturbed) plots the total soil CO2 efflux. The contribution by the above components was evaluated. Soil CO2 efflux was measured continuously by using an automated open system of 10 soil respiration chambers. Data was collected in every two hours from each treatment (one of the chambers recorded basal respiration, 3 chambers were settled on root-excluded treatments and 6 chambers measured control plots). Chambers were moved in every 2 weeks between the repetitions of the treatments. Soil CO2 efflux (mycorrhiza-free, root free, control) data were fitted using a soil respiration model, where soil temperature, soil

  6. Comparison of soil respiration methods in a mid-latitude deciduous forest

    SciTech Connect

    Wayson, C. A.; Randolph, J. C.; Hanson, Paul J; Schmid, H. P.; Grimmond, CSB

    2006-01-01

    In forest ecosystems the single largest respiratory flux influencing net ecosystem productivity (NEP) is the total soil CO2 efflux; however, it is difficult to make measurements of this flux that are accurate at the ecosystem scale. We examined patterns of soil CO2 efflux using five different methods: auto-chambers, portable gas analyzers, eddy covariance along and two models parameterized with the observed data. The relation between soil temperature and soil moisture with soil CO2 effluxes are also investigated, both inter-annually and seasonally, using these observations/results. Soil respiration rates (Rsoil) are greatest during the growing season when soil temperatures are between 15 and 25 C, but some soil CO2 efflux occurs throughout the year. Measured soil respiration was sensitive to soil temperature, particularly during the spring and fall. All measurement methods produced similar annual estimates. Depending on the time of the year, the eddy covariance (flux tower) estimate for ecosystem respiration is similar to or slightly lower than estimates of annual soil CO2 efflux from the other methods. As the eddy covariance estimate includes foliar and stem respiration which the other methods do not; it was expected to be larger (perhaps 15-30%). The auto-chamber system continuously measuring soil CO2 efflux rates provides a level of temporalr esolution that permits investigation of short- to longer term influences of factors on these efflux rates. The expense of building and maintaining an auto chamber system may not be necessary for those esearchers interested in estimating Rsoil annually, but auto-chambers do allow the capture of data from all seasons needed for model parameterization.

  7. Agriculture intensification decreases soil C content and respiration activity in a Mediterranean Vertisol

    NASA Astrophysics Data System (ADS)

    Farina, Roberta; Francaviglia, Rosa; Felici, Barbara; Renzi, Gianluca; Troccoli, Antonio

    2016-04-01

    Adoption of intensive and non-conservative farming practices in Mediterranean areas, often causes a strong reduction of soil organic C, with major side effects on soil functioning and CO2 emissions to atmosphere. The purpose of our research was to evaluate the effect of durum wheat-(Triticum durum Desf.) (DW) based rotations, common in Southern Italy, on soil organic C content and soil potential respiration, after 19 years of cultivation. The rotation experiment was carried out since 1992 in Foggia (Apulia, Italy) at the experimental farm of the Cereal Research Centre in a clayey vertisol. Here we report results concerning two rotations, among seven: continuous durum wheat (CDW) and bare fallow-durum wheat-durum wheat- (BF-DW-DW) compared with an adjoining soil, covered with permanent grassland undisturbed, since 1972, considered at steady state. Results showed a negative trend of soil C in both rotations. The C reduction respect to the undisturbed soil (14.5 g C kg-1 of soil) were 0.15 and 0.13% for CDW and BF-DW-DW, respectively. Daily soil potential respiration was always higher in the undisturbed soil: it was 13.65, 10.46 and 8.64 mg C-CO2/kg soil day-1, for undisturbed soil, BF-DW-DW and DWC respectively. The cumulative respiration in 28 days for CDW and BF-DW-DW rotations compared with undisturbed soil was lower by 23 and 32%, respectively. Among the two rotations compared, BF-DW-DW showed to be slightly more conservative than the DWC rotation for soil C, even though none of the two rotations was able to keep the soil C level at values comparable to steady state, due both to soil disturbance and to lower C inputs respect to the permanent cover.

  8. Microbial community composition explains soil respiration responses to changing carbon inputs along an Andes-to-Amazon elevation gradient

    PubMed Central

    Whitaker, Jeanette; Ostle, Nicholas; Nottingham, Andrew T; Ccahuana, Adan; Salinas, Norma; Bardgett, Richard D; Meir, Patrick; McNamara, Niall P; Austin, Amy

    2014-01-01

    1. The Andes are predicted to warm by 3–5 °C this century with the potential to alter the processes regulating carbon (C) cycling in these tropical forest soils. This rapid warming is expected to stimulate soil microbial respiration and change plant species distributions, thereby affecting the quantity and quality of C inputs to the soil and influencing the quantity of soil-derived CO2 released to the atmosphere. 2. We studied tropical lowland, premontane and montane forest soils taken from along a 3200-m elevation gradient located in south-east Andean Peru. We determined how soil microbial communities and abiotic soil properties differed with elevation. We then examined how these differences in microbial composition and soil abiotic properties affected soil C-cycling processes, by amending soils with C substrates varying in complexity and measuring soil heterotrophic respiration (RH). 3. Our results show that there were consistent patterns of change in soil biotic and abiotic properties with elevation. Microbial biomass and the abundance of fungi relative to bacteria increased significantly with elevation, and these differences in microbial community composition were strongly correlated with greater soil C content and C:N (nitrogen) ratios. We also found that RH increased with added C substrate quality and quantity and was positively related to microbial biomass and fungal abundance. 4. Statistical modelling revealed that RH responses to changing C inputs were best predicted by soil pH and microbial community composition, with the abundance of fungi relative to bacteria, and abundance of gram-positive relative to gram-negative bacteria explaining much of the model variance. 5. Synthesis. Our results show that the relative abundance of microbial functional groups is an important determinant of RH responses to changing C inputs along an extensive tropical elevation gradient in Andean Peru. Although we do not make an experimental test of the effects of climate

  9. Effects of Simulated Nitrogen Deposition on Soil Respiration in a Populus euphratica Community in the Ebinur Lake Area, a Desert Ecosystem of Northwestern China.

    PubMed

    He, Xuemin; Lv, Guanghui; Qin, Lu; Chang, Shunli; Yang, Min; Yang, Jianjun; Yang, Xiaodong

    2015-01-01

    One of the primary limiting factors for biological activities in desert ecosystems is nitrogen (N). This study therefore examined the effects of N and investigated the responses of an arid ecosystem to global change. We selected the typical desert plant Populus euphratica in a desert ecosystem in the Ebinur Lake area to evaluate the effects of N deposition on desert soil respiration. Three levels of N deposition (0, 37.5 and 112.5 kg·N·ha-1·yr-1) were randomly artificially provided to simulate natural N deposition. Changes in the soil respiration rates were measured from July to September in both 2010 and 2013, after N deposition in April 2010. The different levels of N deposition affected the total soil N, soil organic matter, soil C/N ratio, microorganism number, and microbial community structure and function. However, variable effects were observed over time in relation to changes in the magnitude of N deposition. Simulated high N deposition significantly reduced the soil respiration rate by approximately 23.6±2.5% (P<0.05), whereas low N deposition significantly increased the soil respiration rate by approximately 66.7±2.7% (P<0.05). These differences were clearer in the final growth stage (September). The different levels of N deposition had little effect on soil moisture, whereas N deposition significantly increased the soil temperature in the 0-5 cm layer (P<0.05). These results suggest that in the desert ecosystem of the Ebinur Lake area, N deposition indirectly changes the soil respiration rate by altering soil properties. PMID:26379186

  10. Effects of Simulated Nitrogen Deposition on Soil Respiration in a Populus euphratica Community in the Ebinur Lake Area, a Desert Ecosystem of Northwestern China

    PubMed Central

    He, Xuemin; Lv, Guanghui; Qin, Lu; Chang, Shunli; Yang, Min; Yang, Jianjun; Yang, Xiaodong

    2015-01-01

    One of the primary limiting factors for biological activities in desert ecosystems is nitrogen (N). This study therefore examined the effects of N and investigated the responses of an arid ecosystem to global change. We selected the typical desert plant Populus euphratica in a desert ecosystem in the Ebinur Lake area to evaluate the effects of N deposition on desert soil respiration. Three levels of N deposition (0, 37.5 and 112.5 kg·N·ha-1·yr-1) were randomly artificially provided to simulate natural N deposition. Changes in the soil respiration rates were measured from July to September in both 2010 and 2013, after N deposition in April 2010. The different levels of N deposition affected the total soil N, soil organic matter, soil C/N ratio, microorganism number, and microbial community structure and function. However, variable effects were observed over time in relation to changes in the magnitude of N deposition. Simulated high N deposition significantly reduced the soil respiration rate by approximately 23.6±2.5% (P<0.05), whereas low N deposition significantly increased the soil respiration rate by approximately 66.7±2.7% (P<0.05). These differences were clearer in the final growth stage (September). The different levels of N deposition had little effect on soil moisture, whereas N deposition significantly increased the soil temperature in the 0–5 cm layer (P<0.05). These results suggest that in the desert ecosystem of the Ebinur Lake area, N deposition indirectly changes the soil respiration rate by altering soil properties. PMID:26379186

  11. Effects of Simulated Nitrogen Deposition on Soil Respiration in a Populus euphratica Community in the Ebinur Lake Area, a Desert Ecosystem of Northwestern China.

    PubMed

    He, Xuemin; Lv, Guanghui; Qin, Lu; Chang, Shunli; Yang, Min; Yang, Jianjun; Yang, Xiaodong

    2015-01-01

    One of the primary limiting factors for biological activities in desert ecosystems is nitrogen (N). This study therefore examined the effects of N and investigated the responses of an arid ecosystem to global change. We selected the typical desert plant Populus euphratica in a desert ecosystem in the Ebinur Lake area to evaluate the effects of N deposition on desert soil respiration. Three levels of N deposition (0, 37.5 and 112.5 kg·N·ha-1·yr-1) were randomly artificially provided to simulate natural N deposition. Changes in the soil respiration rates were measured from July to September in both 2010 and 2013, after N deposition in April 2010. The different levels of N deposition affected the total soil N, soil organic matter, soil C/N ratio, microorganism number, and microbial community structure and function. However, variable effects were observed over time in relation to changes in the magnitude of N deposition. Simulated high N deposition significantly reduced the soil respiration rate by approximately 23.6±2.5% (P<0.05), whereas low N deposition significantly increased the soil respiration rate by approximately 66.7±2.7% (P<0.05). These differences were clearer in the final growth stage (September). The different levels of N deposition had little effect on soil moisture, whereas N deposition significantly increased the soil temperature in the 0-5 cm layer (P<0.05). These results suggest that in the desert ecosystem of the Ebinur Lake area, N deposition indirectly changes the soil respiration rate by altering soil properties.

  12. [Effect of straw pretreatment on soil microbial biomass and respiration activity].

    PubMed

    Li, Guitong; Zhang, Baogui; Li, Baoguo

    2003-12-01

    Winter wheat straw particles (0.5 ~ 2.0mm) were soaked with 8.0 g.L-1 H202(pH11.0), 12.5 g.L-1 Na0H or H2S04 solution for 8 h and dried at 80 degreeC. Soils amended with the pretreated straw and inorganic N were incubated aerobically at 25 degreeC for 60 days. The C02 emission rate and soil microbial biomass C and N were measured at different time. The results showed that during the earlier stage of incubation, the pretreatments of straw increased soil microbial biomass C by 1.0 ~ 1.4 folds, but decreased soil microbial respiration activity. During the later stage of incubation, the Na0H and H2S04 pretreated straw decreased soil microbial biomass carbon by 28% and 42%, respectively, while increased the soil microbial respiration activity. The straw pretreated by H202 increased soil microbial biomass nitrogen by 90% after the 15th day of incubation. The pretreatments of straw increased the fungi/bacteria ratio at different special time. It could be concluded that soil microbial biomass and respiration activity could be changed after the pretreated straw was added into the soil.

  13. Decadal Effects of Elevated CO2 and O3 on Forest Soil Respiration and Belowground Carbon Cycling at Aspen FACE

    NASA Astrophysics Data System (ADS)

    Talhelm, A. F.; Pregitzer, K. S.; Zak, D. R.; Burton, A. J.

    2014-12-01

    Three northern temperate forest communities in the north-central United States were exposed to factorial combinations of elevated carbon dioxide (CO2) and/or tropospheric ozone (O3) for 11 years, advancing from open-grown seedlings <0.25 m in height at the beginning to the experiment to closed-canopy stands that were >8 m tall. Here, we report results from measurements of soil respiration that occurred during the experiment from 1999 to 2008. In order to better understand this flux, we compare changes in soil respiration to the effects of CO2 and O3 on net primary productivity (NPP), fine root biomass, and leaf litter production. Elevated CO2 enhanced soil respiration by an average of 28%. This stimulation of soil respiration varied from +19% to +44%, but did not change consistently during the 10 year measurement period (r2 = 0.04). The effect of elevated O3 on soil respiration was dynamic. In year two of the experiment (1999), elevated O3 decreased soil respiration by 7%. However, soil respiration consistently increased through time under elevated O3 (r2 = 0.71) and was 9% greater than under ambient O3 in the final year of the experiment (2008). Overall, elevated O3 had no meaningful effect on soil respiration (+0.3%). The annual effects of elevated CO2 on soil respiration were not correlated with NPP or fine root biomass, but was positively correlated with leaf litter production (r = 0.57). Annual leaf litter production was also related to the annual effects of elevated O3 on soil respiration (r = 0.78), but relationship was tighter between annual O3 effects on NPP and soil respiration (r = 0.83).

  14. Isotope partitioning of soil respiration: A Bayesian solution to accommodate multiple sources of variability

    NASA Astrophysics Data System (ADS)

    Ogle, Kiona; Pendall, Elise

    2015-02-01

    Isotopic methods offer great potential for partitioning trace gas fluxes such as soil respiration into their different source contributions. Traditional partitioning methods face challenges due to variability introduced by different measurement methods, fractionation effects, and end-member uncertainty. To address these challenges, we describe a hierarchical Bayesian (HB) approach for isotopic partitioning of soil respiration that directly accommodates such variability. We apply our HB method to data from an experiment conducted in a shortgrass steppe ecosystem, where decomposition was previously shown to be stimulated by elevated CO2. Our approach simultaneously fits Keeling plot (KP) models to observations of soil or soil-respired δ13C and [CO2] obtained via chambers and gas wells, corrects the KP intercepts for apparent fractionation (Δ) due to isotope-specific diffusion rates and/or method artifacts, estimates method- and treatment-specific values for Δ, propagates end-member uncertainty, and calculates proportional contributions from two distinct respiration sources ("old" and "new" carbon). The chamber KP intercepts were estimated with greater confidence than the well intercepts and compared to the theoretical value of 4.4‰, our results suggest that Δ varies between 2 and 5.2‰ depending on method (chambers versus wells) and CO2 treatment. Because elevated CO2 plots were fumigated with 13C-depleted CO2, the source contributions were tightly constrained, and new C accounted for 64% (range = 55-73%) of soil respiration. The contributions were less constrained for the ambient CO2 treatments, but new C accounted for significantly less (47%, range = 15-82%) of soil respiration. Our new HB partitioning approach contrasts our original analysis (higher contribution of old C under elevated CO2) because it uses additional data sources, accounts for end-member bias, and estimates apparent fractionation effects.

  15. Temperature-independent diel variation in soil respiration observed from a temperate deciduous forest

    SciTech Connect

    Post, Wilfred M; Liu, Qing; Edwards, Nelson T; Gu, Lianhong; Childs, Joanne; Lenhart, Suzanne M

    2006-01-01

    The response of soil respiration (Rs) to temperature depends largely on the temporal and spatial scales of interest and how other environmental factors interact with this response. They are often represented by empirical exponential equations in many ecosystem analyses because of the difficulties in separating covarying environmental responses and in observing below ground processes. The objective of this study was to quantify a soil temperature-independent component in Rs by examining the diel variation of an Rs time series measured in a temperate deciduous forest located at Oak Ridge, TN, USA between March and December 2003. By fitting 2 hourly, continuous automatic chamber measurements of CO2 efflux at the soil surface to a Q10 function to obtain the temperature-dependent respiration (Rt) and plotting the diel cycles of Rt, Rs, and their difference (Ri), we found that an obvious temperature-independent component exists in Rs during the growing season. The diel cycle of this component has a distinct day/night pattern and agrees well with diel variations in photosynthetically active radiation (PAR) and air temperature. Elevated canopy CO2 concentration resulted in similar patterns in the diel cycle of the temperature-independent component but with different daily average rates in different stages of growing season. We speculate that photosynthesis of the stand is one of the main contributors to this temperature-independent respiration component although more experiments are needed to draw a firm conclusion. We also found that despite its relatively small magnitude compared with the temperature-dependent component, the diel variation in the temperature-independent component can lead to significantly different estimates of the temperature sensitivity of soil respiration in the study forest. As a result, the common practice of using fitted temperature-dependent function from night-time measurements to extrapolate soil respiration during the daytime may underestimate

  16. [Effects of Warming and Straw Application on Soil Respiration and Enzyme Activity in a Winter Wheat Cropland].

    PubMed

    Chen, Shu-tao; Sang, Lin; Zhang, Xu; Hu, Zheng-hua

    2016-02-15

    In order to investigate the effects of warming and straw application on soil respiration and enzyme activity, a field experiment was performed from November 2014 to May 2015. Four treatments, which were control (CK), warming, straw application, and warming and straw application, were arranged in field. Seasonal variability in soil respiration, soil temperature and soil moisture for different treatments were measured. Urease, invertase, and catalase activities for different treatments were measured at the elongation, booting, and anthesis stages. The results showed that soil respiration in different treatments had similar seasonal variation patterns. Seasonal mean soil respiration rates for the CK, warming, straw application, and warming and straw application treatments were 1.46, 1.96, 1.92, and 2.45 micromol x (m2 x s)(-1), respectively. ANOVA indicated that both warming and straw applications significantly (P < 0.05) enhanced soil respiration compared to the control treatment. The relationship between soil respiration and soil temperature in different treatments fitted with the exponential regression function. The exponential regression functions explained 34.3%, 28.1%, 24.6%, and 32.0% variations of soil respiration for CK, warming, straw application, and warming and straw application treatments, respectively. Warming and straw applications significantly (P < 0.05) enhanced urease, invertase, and catalase activities compared to CK. The relationship between soil respiration and urease activity fitted with a linear regression function, with the P value of 0.061. The relationship between soil respiration and invertase (P = 0.013), and between soil respiration and catalase activity (P = 0.002) fitted well with linear regression functions.

  17. [Effects of Warming and Straw Application on Soil Respiration and Enzyme Activity in a Winter Wheat Cropland].

    PubMed

    Chen, Shu-tao; Sang, Lin; Zhang, Xu; Hu, Zheng-hua

    2016-02-15

    In order to investigate the effects of warming and straw application on soil respiration and enzyme activity, a field experiment was performed from November 2014 to May 2015. Four treatments, which were control (CK), warming, straw application, and warming and straw application, were arranged in field. Seasonal variability in soil respiration, soil temperature and soil moisture for different treatments were measured. Urease, invertase, and catalase activities for different treatments were measured at the elongation, booting, and anthesis stages. The results showed that soil respiration in different treatments had similar seasonal variation patterns. Seasonal mean soil respiration rates for the CK, warming, straw application, and warming and straw application treatments were 1.46, 1.96, 1.92, and 2.45 micromol x (m2 x s)(-1), respectively. ANOVA indicated that both warming and straw applications significantly (P < 0.05) enhanced soil respiration compared to the control treatment. The relationship between soil respiration and soil temperature in different treatments fitted with the exponential regression function. The exponential regression functions explained 34.3%, 28.1%, 24.6%, and 32.0% variations of soil respiration for CK, warming, straw application, and warming and straw application treatments, respectively. Warming and straw applications significantly (P < 0.05) enhanced urease, invertase, and catalase activities compared to CK. The relationship between soil respiration and urease activity fitted with a linear regression function, with the P value of 0.061. The relationship between soil respiration and invertase (P = 0.013), and between soil respiration and catalase activity (P = 0.002) fitted well with linear regression functions. PMID:27363163

  18. Riparian land-use and rehabilitation: impact on organic matter input and soil respiration.

    PubMed

    Oelbermann, Maren; Raimbault, Beverly A; Gordon, A M

    2015-02-01

    Rehabilitated riparian zones in agricultural landscapes enhance environmental integrity and provide environmental services such as carbon (C) sequestration. This study quantified differences in organic matter input, soil biochemical characteristics, and soil respiration in a 25-year-old rehabilitated (RH), grass (GRS), and undisturbed natural forest (UNF) riparian zone. Input from herbaceous vegetation was significantly greater (P < 0.05) in the GRS riparian zone, whereas autumnal litterfall was significantly greater (P < 0.05) in the RH riparian zone. Soil bulk density was significantly greater (P < 0.05) in the RH riparian zone, but its soil chemical characteristics were significantly lower. Soil respiration rates were lowest (P < 0.05) in the UNF (106 C m(-2) h(-1)), followed by the RH (169 mg C m(-2) h(-1)) and GRS (194 C m(-2) h(-1)) riparian zones. Soil respiration rates were significantly different (P < 0.05) among seasons, and were significantly correlated with soil moisture (P < 0.05) and soil temperature (P < 0.05) in all riparian zones. Soil potential microbial activity indicated a significantly different (P < 0.05) response of the microbial metabolic diversity in the RH compared to the GRS and UNF riparian zones, and principle component analysis showed a distinct difference in microbial activity among the riparian land-use systems. Rehabilitating degraded riparian zones with trees rather than GRS is a more effective approach to the long-term mitigation of CO2. Therefore, the protection of existing natural/undisturbed riparian forests in agricultural landscapes is equally important as their rehabilitation with trees, given their higher levels of soil organic C and lower soil respiration rates. PMID:25432450

  19. [Temporal-spatial distribution of agricultural diffuse nitrogen pollution and relationship with soil respiration and nitrification].

    PubMed

    Wei, Ouyang; Cai, Guan-Qing; Huang, Hao-Bo; Geng, Xiao-Jun

    2014-06-01

    The soil respiration, nitrification and denitrification processes play an important role on soil nitrogen transformation and diffuse nitrogen loading. These processes are also the chains for soil circle. In this study, the Zhegao watershed located north of Chaohu Lake was selected to explore the interactions of these processes with diffuse nitrogen pollution. The BaPS (Barometric Process Separation) was applied to analyze the soil respiration, nitrification and denitrification processes in farmland and forest. The SWAT (Soil and Water Assessment Tool) simulated the temporal and spatial pattern of diffuse nitrogen loading. As the expanding of farmland and higher level of fertilization, the yearly mean loading of diffuse nitrogen increased sustainably from 1980-1995 to 1996-2012. The monthly loading in 1996-2012 was also higher than that in the period of 1980-1995, which closely related to the precipitation. The statistical analysis indicated that there was a significant difference between two periods. The yearly averaged loading of the whole watershed in 1996-2012 was 10.40 kg x hm(-2), which was 8.10 kg x hm(-2) in 1980-1995. The variance analysis demonstrated that there was also a big difference between the spatial distributions of two periods. The forest soil had much higher soil respiration than the farmland soil. But the farmland had higher nitrification and denitrification rates. The more intensive nitrogen transformation in the farmland contributed to the less diffuse nitrogen loading. As the nitrification rate of farmland was higher than denitrification rate, agricultural diffuse nitrate nitrogen loading would increase and organic nitrogen loading would reduce. The analysis of soil respiration, nitrification and denitrification is helpful for the study of soil nitrogen circle form the aspect of soil biology, which also benefits the control of agricultural diffuse nitrogen pollution.

  20. Riparian land-use and rehabilitation: impact on organic matter input and soil respiration.

    PubMed

    Oelbermann, Maren; Raimbault, Beverly A; Gordon, A M

    2015-02-01

    Rehabilitated riparian zones in agricultural landscapes enhance environmental integrity and provide environmental services such as carbon (C) sequestration. This study quantified differences in organic matter input, soil biochemical characteristics, and soil respiration in a 25-year-old rehabilitated (RH), grass (GRS), and undisturbed natural forest (UNF) riparian zone. Input from herbaceous vegetation was significantly greater (P < 0.05) in the GRS riparian zone, whereas autumnal litterfall was significantly greater (P < 0.05) in the RH riparian zone. Soil bulk density was significantly greater (P < 0.05) in the RH riparian zone, but its soil chemical characteristics were significantly lower. Soil respiration rates were lowest (P < 0.05) in the UNF (106 C m(-2) h(-1)), followed by the RH (169 mg C m(-2) h(-1)) and GRS (194 C m(-2) h(-1)) riparian zones. Soil respiration rates were significantly different (P < 0.05) among seasons, and were significantly correlated with soil moisture (P < 0.05) and soil temperature (P < 0.05) in all riparian zones. Soil potential microbial activity indicated a significantly different (P < 0.05) response of the microbial metabolic diversity in the RH compared to the GRS and UNF riparian zones, and principle component analysis showed a distinct difference in microbial activity among the riparian land-use systems. Rehabilitating degraded riparian zones with trees rather than GRS is a more effective approach to the long-term mitigation of CO2. Therefore, the protection of existing natural/undisturbed riparian forests in agricultural landscapes is equally important as their rehabilitation with trees, given their higher levels of soil organic C and lower soil respiration rates.

  1. Controls on Soil Respiration in a High Elevation Alpine System and the Implications For Soil Carbon Storage in a Changing Climate

    NASA Astrophysics Data System (ADS)

    Schliemann, S. A.

    2015-12-01

    The alpine ecosystem is a dynamic network of heterogeneous soil and vegetation patches. Microsite characteristics are controlled by site geomorphology, underlying bedrock, and landscape position. These microsite characteristics create a complex mosaic of soil moisture and temperature regimes across the landscape. To investigate the relative influences of soil moisture and soil temperature on soil respiration in these varied microsites, 12 study sites were established in June of 2015 in Rocky Mountain National Park, Colorado. Sites were distributed across 3 plots with distinct vegetation and soil regimes: 1) Conifer forest at the upper limit of the tree line 2) Tundra characterized by shallow soil and minimal vegetation consisting of herbs and lichen 3) Tundra characterized by organic-rich, deep soil and abundant vegetation consisting of grasses and sedges. Soil respiration, soil temperature, and soil moisture were measured weekly throughout the snow-free period of 2015. Soil moisture was negatively correlated with soil respiration and soil temperature was positively correlated with soil respiration across the study sites (p <0.001). Soil respiration rates were significantly different from one another in all plots and were highest in the forest plot (maximum 9.6 μmol/ m2/sec) and much lower in the two tundra plots (< 4.5 μmol/ m2/sec) (p < 0.001). These data suggest that as the alpine climate warms, an increase in soil temperature and a longer snow-free period may result in an overall increase in the rate of soil respiration, which could alter the soil carbon pool. In addition, as temperatures rise, the tree line may migrate to a higher elevation. The results of this study suggest that with such a movement, the soil respiration rate will also increase. However the net change in soil organic matter in the newly established forest would not only depend on the soil respiration rate, but on the overall capacity of the new forest soil to retain carbon, especially

  2. How does soil management affect carbon losses from soils?

    NASA Astrophysics Data System (ADS)

    Klik, A.; Trümper, G.

    2009-04-01

    Agricultural soils are a major source as well as a sink of organic carbon (OC). Amount and distribution of OC within the soil and within the landscape are driven by land management but also by erosion and deposition processes. At the other hand the type of soil management influences mineralization and atmospheric carbon dioxide losses by soil respiration. In a long-term field experiment the impacts of soil tillage systems on soil erosion processes were investigated. Following treatments were compared: 1) conventional tillage (CT), 2) conservation tillage with cover crop during the winter period (CS), and 3) no-till with cover crop during winter period (NT). The studies were carried out at three sites in the Eastern part of Austria with annual precipitation amounts from 650 to 900 mm. The soil texture ranged from silt loam to loam. Since 2007 soil CO2 emissions are measured with a portable soil respiration system in intervals of about one week, but also in relation to management events. Concurrent soil temperature and soil water content are measured and soil samples are taken for chemical and microbiological analyses. An overall 14-yr. average soil loss between 1.0 t.ha-1.yr-1 for NT and 6.1 t.ha-1.yr-1 for CT resulted in on-site OC losses from 18 to 79 kg ha-1.yr-1. The measurements of the carbon dioxide emissions from the different treatments indicate a high spatial variation even within one plot. Referred to CT plots calculated carbon losses amounted to 65-94% for NT plots while for the different RT plots they ranged between 84 and 128%. Nevertheless site specific considerations have to be taken into account. Preliminary results show that the adaptation of reduced or no-till management strategies has enormous potential in reducing organic carbon losses from agricultural used soils.

  3. A parameterization of respiration in frozen soils based on substrate availability

    NASA Astrophysics Data System (ADS)

    Schaefer, Kevin; Jafarov, Elchin

    2016-04-01

    Respiration in frozen soils is limited to thawed substrate within the thin water films surrounding soil particles. As temperatures decrease and the films become thinner, the available substrate also decreases, with respiration effectively ceasing at -8 °C. Traditional exponential scaling factors to model this effect do not account for substrate availability and do not work at the century to millennial timescales required to model the fate of the nearly 1100 Gt of carbon in permafrost regions. The exponential scaling factor produces a false, continuous loss of simulated permafrost carbon in the 20th century and biases in estimates of potential emissions as permafrost thaws in the future. Here we describe a new frozen biogeochemistry parameterization that separates the simulated carbon into frozen and thawed pools to represent the effects of substrate availability. We parameterized the liquid water fraction as a function of temperature based on observations and use this to transfer carbon between frozen pools and thawed carbon in the thin water films. The simulated volumetric water content (VWC) as a function of temperature is consistent with observed values and the simulated respiration fluxes as a function of temperature are consistent with results from incubation experiments. The amount of organic matter was the single largest influence on simulated VWC and respiration fluxes. Future versions of the parameterization should account for additional, non-linear effects of substrate diffusion in thin water films on simulated respiration. Controlling respiration in frozen soils based on substrate availability allows us to maintain a realistic permafrost carbon pool by eliminating the continuous loss caused by the original exponential scaling factors. The frozen biogeochemistry parameterization is a useful way to represent the effects of substrate availability on soil respiration in model applications that focus on century to millennial timescales in permafrost regions.

  4. Estimation of autotrophic soil respiration in a boreal forest using three different approaches

    NASA Astrophysics Data System (ADS)

    Kulmala, Liisa; Pumpanen, Jukka; Heinonsalo, Jussi

    2016-04-01

    It is generally challenging to separate autotrophic and heterotrophic soil respiration. The reason for these difficulties is connected with the intimate interaction of the key processes in soil. Root-associated microbes practically colonize the whole soil volume while decomposition processes occur in the same matrix. Therefore, autotrophic and heterotrophic processes cannot be separated in natural systems. However, there are several methods that can be used to better understand the dynamics of these two. A classical method is called 'trenching' where a trench is dug around a known volume of soil and the roots entering the soil are cut from the living trees thus blocking the C flow from them. The second way to separate autotrophic and heterotrophic respiration relies on the difference in the isotopic signature (13C) of plant-derived or decomposition-derived CO2. The third way to separate the sources is to study the differences in the short- and long-term temperature dependencies in CO2 soil emissions. This is possible especially in boreal forests where the biological activity has a strong seasonal cycle. We compared these three methods in an experiment conducted in a southern boreal middle-aged Scots pine stand in Finland. Our data provides a unique possibility to critically evaluate current methods for estimating autotrophic and heterotrophic soil respiration. The knowledge is needed to study further plant physiology and plant-microbe interactions in soil.

  5. Effects of Forest Age on Soil Autotrophic and Heterotrophic Respiration Differ between Evergreen and Deciduous Forests

    PubMed Central

    Wang, Wei; Zeng, Wenjing; Chen, Weile; Yang, Yuanhe; Zeng, Hui

    2013-01-01

    We examined the effects of forest stand age on soil respiration (SR) including the heterotrophic respiration (HR) and autotrophic respiration (AR) of two forest types. We measured soil respiration and partitioned the HR and AR components across three age classes ∼15, ∼25, and ∼35-year-old Pinus sylvestris var. mongolica (Mongolia pine) and Larix principis-rupprechtii (larch) in a forest-steppe ecotone, northern China (June 2006 to October 2009). We analyzed the relationship between seasonal dynamics of SR, HR, AR and soil temperature (ST), soil water content (SWC) and normalized difference vegetation index (NDVI, a plant greenness and net primary productivity indicator). Our results showed that ST and SWC were driving factors for the seasonal dynamics of SR rather than plant greenness, irrespective of stand age and forest type. For ∼15-year-old stands, the seasonal dynamics of both AR and HR were dependent on ST. Higher Q10 of HR compared with AR occurred in larch. However, in Mongolia pine a similar Q10 occurred between HR and AR. With stand age, Q10 of both HR and AR increased in larch. For Mongolia pine, Q10 of HR increased with stand age, but AR showed no significant relationship with ST. As stand age increased, HR was correlated with SWC in Mongolia pine, but for larch AR correlated with SWC. The dependence of AR on NDVI occurred in ∼35-year-old Mongolia pine. Our study demonstrated the importance of separating autotrophic and heterotrophic respiration components of SR when stimulating the response of soil carbon efflux to environmental changes. When estimating the response of autotrophic and heterotrophic respiration to environmental changes, the effect of forest type on age-related trends is required. PMID:24282560

  6. Effects of forest age on soil autotrophic and heterotrophic respiration differ between evergreen and deciduous forests.

    PubMed

    Wang, Wei; Zeng, Wenjing; Chen, Weile; Yang, Yuanhe; Zeng, Hui

    2013-01-01

    We examined the effects of forest stand age on soil respiration (SR) including the heterotrophic respiration (HR) and autotrophic respiration (AR) of two forest types. We measured soil respiration and partitioned the HR and AR components across three age classes ~15, ~25, and ~35-year-old Pinus sylvestris var. mongolica (Mongolia pine) and Larix principis-rupprechtii (larch) in a forest-steppe ecotone, northern China (June 2006 to October 2009). We analyzed the relationship between seasonal dynamics of SR, HR, AR and soil temperature (ST), soil water content (SWC) and normalized difference vegetation index (NDVI, a plant greenness and net primary productivity indicator). Our results showed that ST and SWC were driving factors for the seasonal dynamics of SR rather than plant greenness, irrespective of stand age and forest type. For ~15-year-old stands, the seasonal dynamics of both AR and HR were dependent on ST. Higher Q10 of HR compared with AR occurred in larch. However, in Mongolia pine a similar Q10 occurred between HR and AR. With stand age, Q10 of both HR and AR increased in larch. For Mongolia pine, Q10 of HR increased with stand age, but AR showed no significant relationship with ST. As stand age increased, HR was correlated with SWC in Mongolia pine, but for larch AR correlated with SWC. The dependence of AR on NDVI occurred in ~35-year-old Mongolia pine. Our study demonstrated the importance of separating autotrophic and heterotrophic respiration components of SR when stimulating the response of soil carbon efflux to environmental changes. When estimating the response of autotrophic and heterotrophic respiration to environmental changes, the effect of forest type on age-related trends is required.

  7. The spatial patterns of soil respiration regulated by biological and environmental variables along a precipitation gradient

    NASA Astrophysics Data System (ADS)

    Xu, W.; Li, X.; Liu, W.; Li, L.; Hou, L.; Shi, H.; Xia, J.; Liu, D.; Zhang, H.; Chen, Y.; Cai, W.; Fu, Y.; Yuan, W.

    2015-12-01

    Precipitation is a key environmental factor in determining ecosystem structure and function. Knowledge of how soil respiration responds to climate change (precipitation etc.) and human activities (grazing, clipping etc.) is crucial for assessing the impacts of climate change on terrestrial ecosystems and for improving model simulations and predictions of future global C cycling in response to human activities. In this study, we examined the spatial patterns of soil respiration along a precipitation gradient from 176.7 mm to 398.1 mm. Our results showed that soil respiration increased linearly with increasing mean annual precipitation. The increasing trend was similar to the trends of shoot biomass, litter biomass and soil total C content along the precipitation gradient. Root biomass was described by quadratic curves along the increasing precipitation gradient and may result from the tradeoff of environmental regulation and carbon allocation. Our results indicated that precipitation was the primary controlling factor in determining the spatial pattern of soil respiration. The linear/nonlinear relationships in this study describing the variations of the ecosystem carbon process with precipitation could be useful for model development, parameterization and validation at the regional scale to improve predictions of how the carbon process in grasslands responds to climate change, land use and grassland management.

  8. [Effects of Reduced Water and Diurnal Warming on Winter-Wheat Biomass and Soil Respiration].

    PubMed

    Wu, Yang-zhou; Chen, Jian; Hu, Zheng-hua; Xie, Yan; Chen, Shu-tao; Zhang, Xue-song; Shen, Shuang-he; Chen, Xi

    2016-01-15

    Field experiments were conducted in winter wheat-growing season to investigate the effect of reduced water and diurnal warming on wheat biomass and soil respiration. The experimental treatments included the control (CK), 30% reduced water (W), diurnal warming (T, enhanced 2 degrees C), and the combined treatment (TW, 30% reduced water plus diurnal warming 2 degrees C). Soil respiration rate was measured using a static chamber-gas chromatograph technique. The results showed that in the winter wheat-growing season, compared to CK, T and TW treatments significantly increased shoot biomass by 46.0% (P = 0.002) and 19.8% (P = 0.032) during the elongation-booting stage, respectively. T and TW treatments also significantly increased the harvested shoot biomass by 19.8% (P = 0.050) and 34.6% (P = 0.028), respectively. On the other hand, W treatment had no significant effect on shoot biomass, and W, T, and TW treatments didn't significantly change the root biomass. T and W treatments had no significant effect on the mean respiration rate (MRR) of soil (P > 0.05). TW treatment significantly decreased soil MRR by 22.4% (P = 0.049). We also found T treatment decreased the temperature sensitivity coefficients of soil respiration (Q10). The results of our study suggested that compared to the single treatment (reduced water or diurnal warming), the combined treatment (reduced water plus diurnal warming) may have different effects on agroecosystem.

  9. [Effects of Reduced Water and Diurnal Warming on Winter-Wheat Biomass and Soil Respiration].

    PubMed

    Wu, Yang-zhou; Chen, Jian; Hu, Zheng-hua; Xie, Yan; Chen, Shu-tao; Zhang, Xue-song; Shen, Shuang-he; Chen, Xi

    2016-01-15

    Field experiments were conducted in winter wheat-growing season to investigate the effect of reduced water and diurnal warming on wheat biomass and soil respiration. The experimental treatments included the control (CK), 30% reduced water (W), diurnal warming (T, enhanced 2 degrees C), and the combined treatment (TW, 30% reduced water plus diurnal warming 2 degrees C). Soil respiration rate was measured using a static chamber-gas chromatograph technique. The results showed that in the winter wheat-growing season, compared to CK, T and TW treatments significantly increased shoot biomass by 46.0% (P = 0.002) and 19.8% (P = 0.032) during the elongation-booting stage, respectively. T and TW treatments also significantly increased the harvested shoot biomass by 19.8% (P = 0.050) and 34.6% (P = 0.028), respectively. On the other hand, W treatment had no significant effect on shoot biomass, and W, T, and TW treatments didn't significantly change the root biomass. T and W treatments had no significant effect on the mean respiration rate (MRR) of soil (P > 0.05). TW treatment significantly decreased soil MRR by 22.4% (P = 0.049). We also found T treatment decreased the temperature sensitivity coefficients of soil respiration (Q10). The results of our study suggested that compared to the single treatment (reduced water or diurnal warming), the combined treatment (reduced water plus diurnal warming) may have different effects on agroecosystem. PMID:27078968

  10. Root and microbial respiration from urban, agricultural and natural soils within the Moscow megapolis

    NASA Astrophysics Data System (ADS)

    Vasenev, Viacheslav; Castaldi, Simona; Vizirskaya, Marya; Ananyeva, Nadezhda; Ivashchenko, Kristina; Valentini, Riccardo; Vasenev, Ivan

    2015-04-01

    Urbanization is an important process of land-use change, which is increasing with the growth of population and abandonment of rural areas. Urbanization alters profoundly soil features and functions, among which soil respiration, which is one of the main carbon fluxes to the atmosphere. Soil respiration is the result of heterotrophic and autotrophic components, which are driven by biotic and abiotic factors. Little is known about soil respiration and its components in urban environments, which represent highly variable systems, characterized by different functional zones, types and intensities of urban management. In the present study we analyzed the spatial variability and temporal dynamics of total soil respiration (Rs) and its components, autotrophic (Ra) and heterotrophic respiration (Rh), from soils of different environments included in the Moscow megalopolis area. In particular we compared highly impacted areas urban green lawns with less anthropized ecosystems within the Moscow city: arable lands and urban forest sites. Experiments were set after snow melt and respiration fluxes were analyzed during the whole summer period till the beginning of the autumn. Data showed that Rs was significantly higher in the most disturbed sites, the green lawns, and showed the highest variability among the three analyzed land use types. Rh was the dominant component of soil respiration in all sites and did not vary significantly during the study period. However, significant differences was shown for the metabolic quotient qCO2, estimated as heterotrophic respiration ratio to microbial carbon (Rh/Cmic). The most disturbed sites showed the highest qCO2 within the lawn land use, followed by arable sites and forest sites, characterized by the lowest qCO2. Ra contributed to total Rs only at a minor extent (26%) and increased in all study sites along the season following the phenological cycle of the plant communities. Ra absolute values and relative contribution to Rs did not

  11. Early season nitrogen limitation of microbial respiration in the organic horizon of tussock tundra soils

    NASA Astrophysics Data System (ADS)

    Darrouzet-Nardi, A.; Wallenstein, M. D.; Steltzer, H.; Sullivan, P.; Melle, C.; Segal, A. D.; Weintraub, M. N.

    2011-12-01

    Low nitrogen (N) availability is a key constraint to decomposition of organic matter in arctic ecosystems. In tussock tundra soils, we have previously observed relatively high N availability early in the growing season followed by a crash in N availability later in the season. This crash led us to hypothesize that N is less limiting to microbial respiration early in the season and more limiting later in the season. To test this hypothesis, we incubated tussock tundra soils for one week in mason jars at three temperatures (5,10,15°C) with either ambient N levels or additional N (112.5 ug N g-1 dry soil). We made early season measurements at the beginning of June and late season measurements at the end of July in both 2010 and 2011. Contrary to our hypothesis, the laboratory incubations suggest that soil respiration is N-limited at both times of the season. The size of the limitation varied with temperature, with the most consistent effect of added N observed at 10°C. Reductions in the C:N ratio of the microbial biomass shows that they readily took up the added N in both the early and late season. We also saw that more carbon overall was respired in the warmer treatments in 2011. Rapid reductions in the respiration rate over the course of the one week incubation, particularly in 2011, suggest that labile carbon is also strongly limiting to microbial respiration in these soils. These data suggest that both carbon and nitrogen limitation to decomposition can occur very early in the growing season, even shortly after the onset of soil thaw. The results of this study reinforce the role of nutrient limitation as an important constraint on the loss of large stocks of carbon from the organic-rich upper layers of tussock tundra soils.

  12. Autotrophic component of soil respiration is repressed by drought more than the heterotrophic one in a dry grassland

    NASA Astrophysics Data System (ADS)

    Balogh, J.; Papp, M.; Pintér, K.; Fóti, Sz.; Posta, K.; Eugster, W.; Nagy, Z.

    2015-10-01

    Summer droughts projected to increase in Central Europe due to climate change strongly influence the carbon cycle of ecosystems. Persistent respiration activities during drought periods are responsible for a significant carbon loss, which may turn the ecosystem from sink to source of carbon. There are still gaps in our knowledge regarding the characteristic changes taking place in the respiration of the different components of the ecosystem respiration in response to drought events. Here, we combined a physical separation of soil respiration components with continuous measurements of soil CO2 efflux and its isotopic (13C) signal at a dry grassland site in Hungary. The physical separation of soil respiration components was achieved by the use of inox meshes and tubes inserted into the soil. The root-excluded and root- and mycorrhiza-excluded treatments served to measure the isotopic signal of the rhizospheric, mycorrhizal fungi and heterotrophic components, respectively. In the dry grassland investigated in this study the three components of the soil CO2 efflux decreased at different rates under drought conditions. During drought the contribution made by the heterotrophic components was the highest. Rhizospheric component was the most sensitive to soil drying with its relative contribution to the total soil respiration dropping from 71 ± 4 % (non-stressed) to 36 ± 12 % under drought conditions. According to our results, the heterotrophic component of soil respiration is the major contributor to the respiration activities during drought events.

  13. Can transgenic maize affect soil microbial communities?

    PubMed

    Mulder, Christian; Wouterse, Marja; Raubuch, Markus; Roelofs, Willem; Rutgers, Michiel

    2006-09-29

    The aim of the experiment was to determine if temporal variations of belowground activity reflect the influence of the Cry1Ab protein from transgenic maize on soil bacteria and, hence, on a regulatory change of the microbial community (ability to metabolize sources belonging to different chemical guilds) and/or a change in numerical abundance of their cells. Litter placement is known for its strong influence on the soil decomposer communities. The effects of the addition of crop residues on respiration and catabolic activities of the bacterial community were examined in microcosm experiments. Four cultivars of Zea mays L. of two different isolines (each one including the conventional crop and its Bacillus thuringiensis cultivar) and one control of bulk soil were included in the experimental design. The growth models suggest a dichotomy between soils amended with either conventional or transgenic maize residues. The Cry1Ab protein appeared to influence the composition of the microbial community. The highly enhanced soil respiration observed during the first 72 h after the addition of Bt-maize residues can be interpreted as being related to the presence of the transgenic crop residues. This result was confirmed by agar plate counting, as the averages of the colony-forming units of soils in conventional treatments were about one-third of those treated with transgenic straw. Furthermore, the addition of Bt-maize appeared to induce increased microbial consumption of carbohydrates in BIOLOG EcoPlates. Three weeks after the addition of maize residues to the soils, no differences between the consumption rate of specific chemical guilds by bacteria in soils amended with transgenic maize and bacteria in soils amended with conventional maize were detectable. Reaped crop residues, comparable to post-harvest maize straw (a common practice in current agriculture), rapidly influence the soil bacterial cells at a functional level. Overall, these data support the existence of short

  14. Microtopographic variation in soil respiration and its controlling factors vary with plant phenophases in a desert-shrub ecosystem

    NASA Astrophysics Data System (ADS)

    Wang, B.; Zha, T. S.; Jia, X.; Gong, J. N.; Wu, B.; Bourque, C. P. A.; Zhang, Y.; Qin, S. G.; Chen, G. P.; Peltola, H.

    2015-10-01

    Soil respiration (Rs) and its biophysical controls were measured over a fixed sand dune in a desert-shrub ecosystem in northwest China in 2012 to explore the mechanisms controlling the spatial heterogeneity in Rs and to understand the plant effects on the spatial variation in Rs in different phenophases. The measurements were carried out on four slope orientations (i.e., windward, leeward, north- and south-facing) and three height positions on each slope (i.e., lower, upper, and top) across the phenophases of the dominant shrub species (Artemisia ordosica). Coefficient of variation (i.e., standard deviation/mean) of Rs across the 11 microsites over our measurement period was 23.5 %. Soil respiration was highest on the leeward slope, and lowest on the windward slope. Over the measurement period, plant-related factors, rather than microhydrometeorological factors, affected the microtopographic variation in Rs. During the flower-bearing phase, root biomass affected Rs most, explaining 72 % of the total variation. During the leaf coloration-defoliation phase, soil nitrogen content affected Rs the most, explaining 56 % of the total variation. Our findings highlight that spatial pattern in Rs was dependent on plant distribution over a desert sand dune, and plant-related factors largely regulated topographic variation in Rs, and such regulations varied with plant phenology.

  15. Mountain pine beetle disturbance effects on soil respiration and nutrient pools

    NASA Astrophysics Data System (ADS)

    Trahan, N. A.; Moore, D. J.; Brayden, B. H.; Dynes, E.; Monson, R. K.

    2011-12-01

    Over the past decade, the mountain pine beetle Dendroctonos ponderosae has infested more than 86 million hectares of high elevation forest in the Western U.S.A. While bark beetles are endemic to western forests and important agents of regeneration, the current mountain pine beetle outbreak is larger than any other on record and the resulting tree mortality has significant consequences for nutrient cycling and regional carbon exchange. We established decade-long parallel disturbance chronosequences in two lodgepole pine (Pinus contorta) forests in Colorado: one composed of mountain pine beetle killed lodgepole stands and one consisting of trees where beetle mortality was simulated by stem girdling. Over the 2010 and 2011 growing season we measured plot level soil respiration fluxes, as well as soil extractable dissolved organic carbon, nitrogen, microbial biomass carbon and nitrogen, and pools of ammonium, nitrate and inorganic phosphorus. We show that soil respiration sharply declines with gross primary productivity after tree mortality, but rebounds during the next 4 years, then declines again from 6-8 years post-disturbance. Soil extractable dissolved organic carbon, microbial biomass carbon, and inorganic phosphorous pools follow the pattern observed in soil respiration fluxes across disturbance age classes for both sites, while patterns in total dissolved nitrogen exhibit site specific variation. Levels of detectable soil nitrate were low and did not significantly change across the chronosequence, while soil ammonium increased in a similar pattern with soil moisture in disturbed plots. These patterns in soil respiration and nutrient pools reflect the loss of autotrophic respiration and rhizodeposition immediately after tree mortality, followed by a pulse in soil efflux linked to the decomposition of older, less labile carbon pools. This pulse is likely controlled by the fall rate of litter, coarse woody debris and the relative impact of post-disturbance water

  16. A Bayesian Deconvolution Approach to Partitioning Soil Respiration: Coupling Carbon Flux and Isotope Data with Process-based Flux and Mixing Models

    NASA Astrophysics Data System (ADS)

    Ogle, K.; Cable, J. M.; Huxman, T. E.

    2006-12-01

    The respiratory loss of carbon from terrestrial ecosystems is a major carbon flux affecting local, regional, and global carbon cycling. Such losses (e.g., soil CO2 efflux), however, are often overly simplified in biogeochemical models compared to processes such as photosynthesis. This discrepancy is partly due to the difficulty associated with partitioning soil respiration (or CO2 efflux) into its various components (e.g., autotrophic vs. heterotrophic). Different components operate at dissimilar temporal and spatial scales, thus estimation of their relative activity based on bulk soil efflux measurements is challenging. Hence, development of a robust, biophysically-inspired method for partitioning the different components is paramount to teasing- apart the mechanisms underlying carbon source-sink dynamics within and across diverse landscapes. Towards this goal, we developed a semi-mechanistic Bayesian deconvolution modeling approach for partitioning soil respiration into its component sources. While the sources can be broadly categorized as autotrophic or heterotrophic, the fundamental sources of biogenic CO2 efflux arises from specific interactions between plants, micro-organisms, and the soil environment. Potential sources have been identified based on their different turnover rates and functional roles, including, (1) activity of roots, (2) rhizomicrobial (e.g., mycorrhiza) respiration, (3) microbial decomposition of plant tissues, (4) microbial activity primed by root exudation, and (5) microbial decomposition of soil organic matter. The relative contribution of each source to soil CO2 efflux can vary within the soil matrix, depending on spatial and temporal variability in soil properties, resource and substrate availability, and microclimate. Our Bayesian deconvolution framework allows for simultaneous analysis of multiple data sources related to soil respiration dynamics, and the data are analyzed within the context of process-based models. The data include

  17. [Response of Soil Respiration and Organic Carbon to Returning of Different Agricultural Straws and Its Mechanism].

    PubMed

    Cao, Zhan-bo; Wang, Lei; Li, Fan; Fu, Xiao-hua; Le, Yi-quan; Wu, Ji-hua; Lu, Bing; Xu, Dian-sheng

    2016-05-15

    Soybean, maize and rice straws were selected as raw materials to study the response of the soil respiration (SR) and soil organic carbon (SOC) to returning of different straws in the Chongming Dongtan area. The results showed that all of SR, SOC and the plant biomass of the lands with returning of different straws were higher than those of the controls. The soil with soybean straw returning possessed the lowest SR and highest SOC among the three kinds of straws, meaning its higher soil organic carbon sequestration capability than corn and maize straws returning. Straw returning significantly enhanced soil dehydrogenase, β-glycosidase activities and microbial biomass, and soil dehydrogenase activity was significantly correlated with soil respiration. The dehydrogenase activity of the soil with soybean straw returning was the lowest, thus, the lowest SR and highest SOC. Soybean straw had the highest cellulose and lignin contents and the lowest N content among the three kinds of straws, resulting in its lowest biodegradability. Therefore, when soybean straw was returned to soil, it was difficult to degrade completely by soil microorganisms, thus the lowest soil microbial activity, eventually leading to the lowest SR and highest SOC.

  18. [Response of Soil Respiration and Organic Carbon to Returning of Different Agricultural Straws and Its Mechanism].

    PubMed

    Cao, Zhan-bo; Wang, Lei; Li, Fan; Fu, Xiao-hua; Le, Yi-quan; Wu, Ji-hua; Lu, Bing; Xu, Dian-sheng

    2016-05-15

    Soybean, maize and rice straws were selected as raw materials to study the response of the soil respiration (SR) and soil organic carbon (SOC) to returning of different straws in the Chongming Dongtan area. The results showed that all of SR, SOC and the plant biomass of the lands with returning of different straws were higher than those of the controls. The soil with soybean straw returning possessed the lowest SR and highest SOC among the three kinds of straws, meaning its higher soil organic carbon sequestration capability than corn and maize straws returning. Straw returning significantly enhanced soil dehydrogenase, β-glycosidase activities and microbial biomass, and soil dehydrogenase activity was significantly correlated with soil respiration. The dehydrogenase activity of the soil with soybean straw returning was the lowest, thus, the lowest SR and highest SOC. Soybean straw had the highest cellulose and lignin contents and the lowest N content among the three kinds of straws, resulting in its lowest biodegradability. Therefore, when soybean straw was returned to soil, it was difficult to degrade completely by soil microorganisms, thus the lowest soil microbial activity, eventually leading to the lowest SR and highest SOC. PMID:27506047

  19. Effects of grazing on photosynthetic features and soil respiration of rangelands in the Tianshan Mountains of Northwest China.

    PubMed

    Liu, Hua; Zang, Runguo; Chen, Han Y H

    2016-01-01

    Rangelands play a critical role in the global carbon cycle. However, the eco-physiological mechanisms associated with the effects of grazing on leaf photosynthesis and soil respiration remain poorly understood. To examine the impacts of grazing on leaf photosynthesis and soil respiration, we measured the photosynthetic parameters of the dominant species (Trifolium repens) and the soil respiration in grazed and ungrazed rangelands in the Tianshan Mountains of China. We found that grazing reduced the daily maximum net photosynthetic rate and soil respiration rates by 35% and 15%, respectively. The photosynthetic quantum yield, dark respiratory rate, and water use efficiency of T. repens leaves were reduced in grazed plots by 33.3%, 69.2%, and 21.5%, respectively. Our results demonstrated that grazing reduced carbon assimilation while increasing soil respiration within the rangelands in the Tianshan Mountains. PMID:27452980

  20. Effects of grazing on photosynthetic features and soil respiration of rangelands in the Tianshan Mountains of Northwest China

    PubMed Central

    Liu, Hua; Zang, Runguo; Chen, Han Y. H.

    2016-01-01

    Rangelands play a critical role in the global carbon cycle. However, the eco-physiological mechanisms associated with the effects of grazing on leaf photosynthesis and soil respiration remain poorly understood. To examine the impacts of grazing on leaf photosynthesis and soil respiration, we measured the photosynthetic parameters of the dominant species (Trifolium repens) and the soil respiration in grazed and ungrazed rangelands in the Tianshan Mountains of China. We found that grazing reduced the daily maximum net photosynthetic rate and soil respiration rates by 35% and 15%, respectively. The photosynthetic quantum yield, dark respiratory rate, and water use efficiency of T. repens leaves were reduced in grazed plots by 33.3%, 69.2%, and 21.5%, respectively. Our results demonstrated that grazing reduced carbon assimilation while increasing soil respiration within the rangelands in the Tianshan Mountains. PMID:27452980

  1. Effects of grazing on photosynthetic features and soil respiration of rangelands in the Tianshan Mountains of Northwest China

    NASA Astrophysics Data System (ADS)

    Liu, Hua; Zang, Runguo; Chen, Han Y. H.

    2016-07-01

    Rangelands play a critical role in the global carbon cycle. However, the eco-physiological mechanisms associated with the effects of grazing on leaf photosynthesis and soil respiration remain poorly understood. To examine the impacts of grazing on leaf photosynthesis and soil respiration, we measured the photosynthetic parameters of the dominant species (Trifolium repens) and the soil respiration in grazed and ungrazed rangelands in the Tianshan Mountains of China. We found that grazing reduced the daily maximum net photosynthetic rate and soil respiration rates by 35% and 15%, respectively. The photosynthetic quantum yield, dark respiratory rate, and water use efficiency of T. repens leaves were reduced in grazed plots by 33.3%, 69.2%, and 21.5%, respectively. Our results demonstrated that grazing reduced carbon assimilation while increasing soil respiration within the rangelands in the Tianshan Mountains.

  2. Effects of aging herbicide mixtures on soil respiration and plant survival in soils from a pesticide-contaminated site

    SciTech Connect

    Kruger, E.L.; Anhalt, J.C.; Anderson, T.A.

    1996-10-01

    Three herbicides, atrazine, metolachlor, and pendimethalin, were applied individually and in all possible combinations to soil taken from a pesticide-contaminated site in Iowa. The rate of application for each chemical was 50 {mu}g/g, representative of contamination problems at mixing and loading areas of agrochemical dealer sites. Treated soils were incubated at 24{degrees}C in the dark for 0, 21, and 63 d, and soil moisture tension was maintained at -33 kPa. Soil respiration was measured daily by using an infrared gas analyzer for 10 d at the end of each incubation period. Subsamples of treated soils were used in plant germination and survival studies. Concentrations of each herbicide were determined by gas chromatography at day 0, 21, and 63. Soil respiration was elevated for the first 6 d immediately following treatment, and then declined to very low levels. At the end of day 21 and 63, soil respiration remained at very low levels. The half-lives for atrazine, metolachlor, and pendimethalin individually in soil or in combination with one and/or the other herbicide will be reported. The results of germination and survival studies with kochia, giant foxtail, birdsfoot trefoil, crown vetch, and soybean will also be reported.

  3. [Analysis of soil respiration and influence factors in wheat farmland under conservation tillage in southwest hilly region].

    PubMed

    Zhang, Sai; Zhang, Xiao-Yu; Wang, Long-Chang; Luo, Hai-Xiu; Zhou, Hang-Fei; Ma, Zhong-Lian; Zhang, Cui-Wei

    2013-07-01

    In order to investigate the effect of conservation tillage on soil respiration in dry cropping farmland in southwest purple hilly region, the LI6400-09 respiratory chamber was adopted in the experiment conducted in the experimental field in Southwest University in Beibei, Chongqing. The respiration and the hydrothermal and biotic factors of soil were measured and analyzed during the growth period of wheat in the triple intercropping system of wheat/maize/soybean. There were four treatments including T (traditional tillage), R (ridge tillage), TS (traditional tillage + straw mulching) and RS (ridge tillage + straw mulching), which were all in triplicates. The results indicated that the soil respiration rate changed in the range of 1.100-2.508 micromol x (m2 x s)(-1) during the reproductive growth stage of wheat. There were significant differences in soil respiration rate among different treatments, which could be ranked as RS > R > TS > T. The soil temperature in the 10cm layer was ranked as T > R > TS > RS. The relationship between soil respiration and soil temperature fitted well with an exponential function, in which the Q10 values were 1.25, 1.20, 1.31 and 1.26, respectively. The soil moisture in the 5cm layer was ranked as TS > RS > T > R. The best fitting model between soil moisture and soil respiration was a parabolic curve, indicating the presence of soil moisture with the strongest soil respiration. The response threshold of wheat to soil moisture was 14.80%-17.47% during the reproductive stage. The dominant groups of soil animals were Collembola and Acarina, which were correlated with soil respiration to some extent. The correlation was high in the treatments T and R, ranged from 0.669-0.921, whereas there was no remarkable correlation in the other treatments. PMID:24028018

  4. [Analysis of soil respiration and influence factors in wheat farmland under conservation tillage in southwest hilly region].

    PubMed

    Zhang, Sai; Zhang, Xiao-Yu; Wang, Long-Chang; Luo, Hai-Xiu; Zhou, Hang-Fei; Ma, Zhong-Lian; Zhang, Cui-Wei

    2013-07-01

    In order to investigate the effect of conservation tillage on soil respiration in dry cropping farmland in southwest purple hilly region, the LI6400-09 respiratory chamber was adopted in the experiment conducted in the experimental field in Southwest University in Beibei, Chongqing. The respiration and the hydrothermal and biotic factors of soil were measured and analyzed during the growth period of wheat in the triple intercropping system of wheat/maize/soybean. There were four treatments including T (traditional tillage), R (ridge tillage), TS (traditional tillage + straw mulching) and RS (ridge tillage + straw mulching), which were all in triplicates. The results indicated that the soil respiration rate changed in the range of 1.100-2.508 micromol x (m2 x s)(-1) during the reproductive growth stage of wheat. There were significant differences in soil respiration rate among different treatments, which could be ranked as RS > R > TS > T. The soil temperature in the 10cm layer was ranked as T > R > TS > RS. The relationship between soil respiration and soil temperature fitted well with an exponential function, in which the Q10 values were 1.25, 1.20, 1.31 and 1.26, respectively. The soil moisture in the 5cm layer was ranked as TS > RS > T > R. The best fitting model between soil moisture and soil respiration was a parabolic curve, indicating the presence of soil moisture with the strongest soil respiration. The response threshold of wheat to soil moisture was 14.80%-17.47% during the reproductive stage. The dominant groups of soil animals were Collembola and Acarina, which were correlated with soil respiration to some extent. The correlation was high in the treatments T and R, ranged from 0.669-0.921, whereas there was no remarkable correlation in the other treatments.

  5. SOIL ORGANIC AMENDMENT AS AFFECTING HERBICIDE FATE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The addition of organic amendments or organic wastes to soils have been shown to affect the fate of soil applied herbicides, although it is an issue very seldom considered when making the decision of fertilizing soil or disposing organic wastes. The addition of organic wastes to soils is viewed as v...

  6. Comparing how land use change impacts soil microbial catabolic respiration in Southwestern Amazon

    PubMed Central

    Mazzetto, Andre Mancebo; Feigl, Brigitte Josefine; Cerri, Carlos Eduardo Pellegrino; Cerri, Carlos Clemente

    2016-01-01

    Land use changes strongly impact soil functions, particularly microbial biomass diversity and activity. We hypothesized that the catabolic respiration response of the microbial biomass would differ depending on land use and that these differences would be consistent at the landscape scale. In the present study, we analyzed the catabolic response profile of the soil microbial biomass through substrate-induced respiration in different land uses over a wide geographical range in Mato Grosso and Rondônia state (Southwest Amazon region). We analyzed the differences among native areas, pastures and crop areas and within each land use and examined only native areas (Forest, Dense Cerrado and Cerrado), pastures (Nominal, Degraded and Improved) and crop areas (Perennial, No-Tillage, Conventional Tillage). The metabolic profile of the microbial biomass was accessed using substrate-induced respiration. Pasture soils showed significant responses to amino acids and carboxylic acids, whereas native areas showed higher responses to malonic acid, malic acid and succinic acid. Within each land use category, the catabolic responses showed similar patterns in both large general comparisons (native area, pasture and crop areas) and more specific comparisons (biomes, pastures and crop types). The results showed that the catabolic responses of the microbial biomass are highly correlated with land use, independent of soil type or climate. The substrate induced respiration approach is useful to discriminate microbial communities, even on a large scale. PMID:26887228

  7. PHYSICOCHEMICAL PROPERTIES AS PREDICTORS OF ORGANIC CHEMICAL EFFECTS ON SOIL MICROBIAL RESPIRATION

    EPA Science Inventory

    Structure-activity analysis was used to evaluate the effects of 19 hazardous organic chemicals on microbial respiration in two slightly acidic soils (a Captina silt loam from Roane County Tennessee, and a McLaurin sandy loam from Stone County, Mississippi), both low in organic ca...

  8. Comparing how land use change impacts soil microbial catabolic respiration in Southwestern Amazon.

    PubMed

    Mazzetto, Andre Mancebo; Feigl, Brigitte Josefine; Cerri, Carlos Eduardo Pellegrino; Cerri, Carlos Clemente

    2016-01-01

    Land use changes strongly impact soil functions, particularly microbial biomass diversity and activity. We hypothesized that the catabolic respiration response of the microbial biomass would differ depending on land use and that these differences would be consistent at the landscape scale. In the present study, we analyzed the catabolic response profile of the soil microbial biomass through substrate-induced respiration in different land uses over a wide geographical range in Mato Grosso and Rondônia state (Southwest Amazon region). We analyzed the differences among native areas, pastures and crop areas and within each land use and examined only native areas (Forest, Dense Cerrado and Cerrado), pastures (Nominal, Degraded and Improved) and crop areas (Perennial, No-Tillage, Conventional Tillage). The metabolic profile of the microbial biomass was accessed using substrate-induced respiration. Pasture soils showed significant responses to amino acids and carboxylic acids, whereas native areas showed higher responses to malonic acid, malic acid and succinic acid. Within each land use category, the catabolic responses showed similar patterns in both large general comparisons (native area, pasture and crop areas) and more specific comparisons (biomes, pastures and crop types). The results showed that the catabolic responses of the microbial biomass are highly correlated with land use, independent of soil type or climate. The substrate induced respiration approach is useful to discriminate microbial communities, even on a large scale. PMID:26887228

  9. Remote sensing-based estimation of annual soil respiration at two contrasting forest sites

    DOE PAGES

    Gu, Lianhong; Huang, Ni; Black, T. Andrew; Wang, Li; Niu, Zheng

    2015-11-23

    Soil respiration (Rs), an important component of the global carbon cycle, can be estimated using remotely sensed data, but the accuracy of this technique has not been thoroughly investigated. In this article, we proposed a methodology for the remote estimation of annual Rs at two contrasting FLUXNET forest sites (a deciduous broadleaf forest and an evergreen needleleaf forest).

  10. Comparing how land use change impacts soil microbial catabolic respiration in Southwestern Amazon.

    PubMed

    Mazzetto, Andre Mancebo; Feigl, Brigitte Josefine; Cerri, Carlos Eduardo Pellegrino; Cerri, Carlos Clemente

    2016-01-01

    Land use changes strongly impact soil functions, particularly microbial biomass diversity and activity. We hypothesized that the catabolic respiration response of the microbial biomass would differ depending on land use and that these differences would be consistent at the landscape scale. In the present study, we analyzed the catabolic response profile of the soil microbial biomass through substrate-induced respiration in different land uses over a wide geographical range in Mato Grosso and Rondônia state (Southwest Amazon region). We analyzed the differences among native areas, pastures and crop areas and within each land use and examined only native areas (Forest, Dense Cerrado and Cerrado), pastures (Nominal, Degraded and Improved) and crop areas (Perennial, No-Tillage, Conventional Tillage). The metabolic profile of the microbial biomass was accessed using substrate-induced respiration. Pasture soils showed significant responses to amino acids and carboxylic acids, whereas native areas showed higher responses to malonic acid, malic acid and succinic acid. Within each land use category, the catabolic responses showed similar patterns in both large general comparisons (native area, pasture and crop areas) and more specific comparisons (biomes, pastures and crop types). The results showed that the catabolic responses of the microbial biomass are highly correlated with land use, independent of soil type or climate. The substrate induced respiration approach is useful to discriminate microbial communities, even on a large scale.

  11. Aspen increase soil moisture, nutrients, organic matter and respiration in Rocky Mountain forest communities.

    PubMed

    Buck, Joshua R; St Clair, Samuel B

    2012-01-01

    Development and change in forest communities are strongly influenced by plant-soil interactions. The primary objective of this paper was to identify how forest soil characteristics vary along gradients of forest community composition in aspen-conifer forests to better understand the relationship between forest vegetation characteristics and soil processes. The study was conducted on the Fishlake National Forest, Utah, USA. Soil measurements were collected in adjacent forest stands that were characterized as aspen dominated, mixed, conifer dominated or open meadow, which includes the range of vegetation conditions that exist in seral aspen forests. Soil chemistry, moisture content, respiration, and temperature were measured. There was a consistent trend in which aspen stands demonstrated higher mean soil nutrient concentrations than mixed and conifer dominated stands and meadows. Specifically, total N, NO(3) and NH(4) were nearly two-fold higher in soil underneath aspen dominated stands. Soil moisture was significantly higher in aspen stands and meadows in early summer but converged to similar levels as those found in mixed and conifer dominated stands in late summer. Soil respiration was significantly higher in aspen stands than conifer stands or meadows throughout the summer. These results suggest that changes in disturbance regimes or climate scenarios that favor conifer expansion or loss of aspen will decrease soil resource availability, which is likely to have important feedbacks on plant community development.

  12. Old soil carbon losses increase with ecosystem respiration in experimentally thawed tundra

    NASA Astrophysics Data System (ADS)

    Hicks Pries, Caitlin E.; Schuur, Edward A. G.; Natali, Susan M.; Crummer, K. Grace

    2016-02-01

    Old soil carbon (C) respired to the atmosphere as a result of permafrost thaw has the potential to become a large positive feedback to climate change. As permafrost thaws, quantifying old soil contributions to ecosystem respiration (Reco) and understanding how these contributions change with warming is necessary to estimate the size of this positive feedback. We used naturally occurring C isotopes (δ13C and Δ14C) to partition Reco into plant, young soil and old soil sources in a subarctic air and soil warming experiment over three years. We found that old soil contributions to Reco increased with soil temperature and Reco flux. However, the increase in the soil warming treatment was smaller than expected because experimentally warming the soils increased plant contributions to Reco by 30%. On the basis of these data, an increase in mean annual temperature from -5 to 0 °C will increase old soil C losses from moist acidic tundra by 35-55 g C m-2 during the growing season. The largest losses will probably occur where the plant response to warming is minimal.

  13. The effect of young biochar on soil respiration

    SciTech Connect

    Smith, Jeffery L.; Collins, Harold P.; Bailey, Vanessa L.

    2010-12-01

    The low temperature pyrolysis of organic material produces biochar, a charcoal like substance. Biochar is being promoted as a soil amendment to enhance soil quality, it is also seen as a mechanism of lomg-term sequestration of carbon. Our experiments tested the hypothesis that biochar is inert in soil. However, we measured an increase in CO2 production from soils after biochar amendment which increased with increasing rates of biochar. The ∂13C signature of the CO2 evolved in the first several days of the incubation was the same as the ∂13C signature of the biochar, confirming that biochar contributed to the CO2 flux. This effect diminished by day 6 of the incubation suggesting that most of the biochar C is slowly decomposing. Thus, aside from this short term mineralization increasing soil C with biochar may indeed be a long term C storage mechanism.

  14. Response of δ13C in plant and soil respiration to a water pulse

    NASA Astrophysics Data System (ADS)

    Salmon, Y.; Buchmann, N.; Barnard, R. L.

    2011-05-01

    Stable carbon isotopes have been used to assess the coupling between changes in environmental conditions and the response of soil or ecosystem respiration, usually by studying the time-lagged response of δ13C of respired CO2 (δ13CR) to changes in photosynthetic carbon isotope discrimination (Δi). However, the lack of a systematic response of δ13CR to environmental changes in field studies stresses the need to better understand the mechanisms to this response. We experimentally created a wide range of carbon allocation and respiration conditions in Fagus sylvatica mesocosms, by growing saplings under different temperatures and girdling combinations. After a period of drought, a water pulse was applied and the short-term responses of δ13C in soil CO2 efflux (δ13CRsoil) and δ13C in aboveground plant respiration (δ13CRabove) were measured, as well as leaf gas exchange rates and soil microbial biomass δ13C responses. Both δ13CRsoil and δ 13CRabove values of all the trees decreased immediately after the water pulse. These responses were not driven by changes in Δi, but rather by a fast release of C stored in roots and shoots. Changes in δ13CRsoil associated with the water pulse were significantly positively correlated with changes in stomatal conductance, showing a strong impact of the plant component on δ13CRsoil. However, three days after the water pulse in girdled trees, changes in δ13CRsoil were related to changes in microbial biomass δ13C, suggesting that changes in the carbon source respired by soil microorganisms also contributed to the response of δ13CRsoil. Our study shows that improving our mechanistic understanding of the responses of δ13CR to changes in environmental conditions requires the understanding of not only the plant's physiological responses, but also the responses of soil microorganisms and of plant-microbial interactions.

  15. Modelling in situ enzyme potential of soils: a tool to predict soil respiration from agricultural fields

    NASA Astrophysics Data System (ADS)

    Shahbaz Ali, Rana; Poll, Christian; Demyan, Scott; Nkwain Funkuin, Yvonne; Ingwersen, Joachim; Wizemann, Hans-Dieter; Kandeler, Ellen

    2014-05-01

    The fate of soil organic carbon (SOC) is one of the largest uncertainties in predicting future climate and terrestrial ecosystem functions. Extra-cellular enzymes, produced by microorganisms, perform the very first step in SOC degradation and serve as key components in global carbon cycling. Very little information is available about the seasonal variation in the temperature sensitivity of soil enzymes. Here we aim to model in situ enzyme potentials involved in the degradation of either labile or recalcitrant organic compounds to understand the temporal variability of degradation processes. To identify the similarities in seasonal patterns of soil respiration and in situ enzyme potentials, we compared the modelled in situ enzyme activities with weekly measured soil CO2 emissions. Arable soil samples from two different treatments (4 years fallow and currently vegetated plots; treatments represent range of carbon input into soil) were collected every month from April, 2012 to April, 2013, from two different study regions (Kraichgau and Swabian Alb) in Southwest Germany. The vegetation plots were under crop rotation in both study areas. We measured activities of three enzymes including β-glucosidase, xylanase and phenoloxidase at five different temperatures. We also measured soil microbial biomass in form of microbial carbon (Cmic). Land-use and area had significant effects (P < 0.001) on the microbial biomass; fallow plots having less Cmic than vegetation plots. Potential activities of β-glucosidase (P < 0.001) and xylanase (P < 0.01) were significantly higher in the vegetation plots of the Swabian Alb region than in the Kraichgau region. In both study areas, enzyme activities were higher during vegetation period and lower during winter which points to the importance of carbon input and/or temperature and soil moisture. We calculated the temperature sensitivity (Q10) of enzyme activities based on laboratory measurements of enzyme activities at a range of incubation

  16. Soil carbon dynamics in oak and Norway spruce afforestation chronosequences on former cropland: heterotrophic respiration and decomposability of organic matter

    NASA Astrophysics Data System (ADS)

    Vesterdal, Lars; Masudur Rahman, Md.; Gomez de la Bárcena, Teresa

    2014-05-01

    /N ratio in addition to a significant decrease in soil pH. These changes were most pronounced in the 0-5 cm layer. We conclude that the respiration flux of C from mineral soil increased with time since afforestation in a 45-year perspective, whereas the decomposability of SOC was unchanged. Tree species did not affect SOC dynamics to any large extent, but respiration fluxes were lower in 5-15 cm under Norway spruce than oak, and SOC decomposability tended to be lower under spruce in the same layer. This suggests that RH fluxes along the chronosequence are controlled by the amount of SOC in soils rather than by changed decomposability of SOC four decades after afforestation of former cropland. The results also indicate that initial losses and later gains in SOC stocks after afforestation would be more driven by temporal changes in litter input than by decreasing SOC decomposability in mineral soil. However, RH/SOM was lower in the 200-year-old oak stand on former cropland suggesting that SOC may become more stable in the long-term after afforestation.

  17. Impact of different tillage treatments on soil respiration and microbial activity for different agricultural used soils in Austria

    NASA Astrophysics Data System (ADS)

    Klik, Andreas; Scholl, Gerlinde; Baatar, Undrakh-Od

    2015-04-01

    Soils can act as a net sink for sequestering carbon and thus attenuating the increase in atmospheric carbon dioxide if appropriate soil and crop management is applied. Adapted soil management strategies like less intensive or even no tillage treatments may result in slower mineralization of soil organic carbon and enhanced carbon sequestration. In order to assess the impact of different soil tillage systems on carbon dioxide emissions due to soil respiration and on soil biological activity parameters, a field study of three years duration (2007-2010)has been performed at different sites in Austria. Following tillage treatments were compared: 1) conventional tillage (CT) with plough with and without cover crop during winter period, 2) reduced tillage (RT) with cultivator with cover crop, and 3) no-till (NT) with cover crop. Each treatment was replicated three times. At two sites with similar climatic conditions but different soil textures soil CO2 efflux was measured during the growing seasons in intervals of one to two weeks using a portable soil respiration system consisting of a soil respiration chamber attached to an infrared gas analyzer. Additionally, concurrent soil temperature and soil water contents of the top layer (0-5 cm)were measured. For these and additional three other sites with different soil and climatic conditions soil samples were taken to assess the impact of tillage treatment on soil biological activity parameters. In spring, summer and autumn samples were taken from each plot at the soil depth of 0-10, 10-20, and 20-30 cm to analyze soil microbial respiration (MR), substrate induced respiration (SIR), beta-glucasidase activity (GLU) and dehydrogenase (BHY). Samples were sieved (2 mm) and stored at 4 °C in a refrigerator. Analyses of were performed within one month after sampling. The measurements show a high spatial variability of soil respiration data even within one plot. Nevertheless, the level of soil carbon dioxide efflux was similar for

  18. Rapid rebound of soil respiration following partial stand disturbance by tree girdling in a temperate deciduous forest.

    PubMed

    Levy-Varon, Jennifer H; Schuster, William S F; Griffin, Kevin L

    2014-04-01

    Forests serve an essential role in climate change mitigation by removing CO2 from the atmosphere. Within a forest, disturbance events can greatly impact C cycling and subsequently influence the exchange of CO2 between forests and the atmosphere. This connection makes understanding the forest C cycle response to disturbance imperative for climate change research. The goal of this study was to examine the temporal response of soil respiration after differing levels of stand disturbance for 3 years at the Black Rock Forest (southeastern NY, USA; oaks comprise 67% of the stand). Tree girdling was used to mimic pathogen attack and create the following treatments: control, girdling all non-oaks (NOG), girdling half of the oak trees (O50), and girdling all the oaks (OG). Soil respiratory rates on OG plots declined for 2 years following girdling before attaining a full rebound of belowground activity in the third year. Soil respiration on NOG and O50 were statistically similar to the control for the duration of the study although a trend for a stronger decline in respiration on O50 relative to NOG occurred in the first 2 years. Respiratory responses among the various treatments were not proportional to the degree of disturbance and varied over time. The short-lived respiratory response on O50 and OG suggests that belowground activity is resilient to disturbance; however, sources of the recovered respiratory flux on these plots are likely different than they were pre-treatment. The differential taxon response between oaks and non-oaks suggests that after a defoliation or girdling event, the temporal response of the soil respiratory flux may be related to the C allocation pattern of the affected plant group.

  19. Rapid rebound of soil respiration following partial stand disturbance by tree girdling in a temperate deciduous forest.

    PubMed

    Levy-Varon, Jennifer H; Schuster, William S F; Griffin, Kevin L

    2014-04-01

    Forests serve an essential role in climate change mitigation by removing CO2 from the atmosphere. Within a forest, disturbance events can greatly impact C cycling and subsequently influence the exchange of CO2 between forests and the atmosphere. This connection makes understanding the forest C cycle response to disturbance imperative for climate change research. The goal of this study was to examine the temporal response of soil respiration after differing levels of stand disturbance for 3 years at the Black Rock Forest (southeastern NY, USA; oaks comprise 67% of the stand). Tree girdling was used to mimic pathogen attack and create the following treatments: control, girdling all non-oaks (NOG), girdling half of the oak trees (O50), and girdling all the oaks (OG). Soil respiratory rates on OG plots declined for 2 years following girdling before attaining a full rebound of belowground activity in the third year. Soil respiration on NOG and O50 were statistically similar to the control for the duration of the study although a trend for a stronger decline in respiration on O50 relative to NOG occurred in the first 2 years. Respiratory responses among the various treatments were not proportional to the degree of disturbance and varied over time. The short-lived respiratory response on O50 and OG suggests that belowground activity is resilient to disturbance; however, sources of the recovered respiratory flux on these plots are likely different than they were pre-treatment. The differential taxon response between oaks and non-oaks suggests that after a defoliation or girdling event, the temporal response of the soil respiratory flux may be related to the C allocation pattern of the affected plant group. PMID:24337785

  20. Effects of nitrogen fertilization on soil N2O emissions and soil respiration in temperate grassland in Inner Mongolia, China

    NASA Astrophysics Data System (ADS)

    Dong, Y.; Qi, Y.; Peng, Q.

    2012-04-01

    Nitrogen addition to soil can play a vital role in influencing nitrogen balance and the losses of soil carbon by respiration in N-deficient terrestrial ecosystems. The aim of this study was to clarify the effects of different levels of nitrogen fertilization (HN:200 kg N ha-1y-1, MN:100 kg N ha-1y-1 and LN:50 kg N ha-1y-1) on soil N2O emissions and soil respiration compared with non-fertilization(CK, 0 kg N ha-1y-1), from July 2007 to September 2008, in temperate grassland in Inner Mongolia, China. Several N fertilizer forms were included(CAN:calcium ammonium nitrate, AS:ammonium sulphate and NS:sodium nitrate) and a static closed chamber method was used as gas fluxes measurement. Our data showed that peak N2O fluxes induced by N treatments were concentrated in short periods (2 to 3 weeks) after fertilization in summer and in soil thawing periods in early spring; there were similarly low N2O fluxes from all treatments in the remaining seasons of the year. The three N levels increased annual N2O emissions significantly(P<0.05) in the order of MN>HN>LN compared with the CK(control) treatment in year 1; in year 2, the elevation of annual N2O emissions was significant (P<0.05) by HN and MN treatments but was insignificant by LN treatments (P>0.05). The three N forms also had strong effects on N2O emissions. Significantly (P<0.05) higher annual N2O emissions were observed in the soils of CAN and AS fertilizer treatments than in the soils of NS fertilizer treatments in both measured years, but the difference between CAN and AS was not significant (P>0.05). Annual N2O emission factors (EF) ranged from 0.060 to 0.298% for different N fertilizer treatments in the two observed years, with an overall EF value of 0.125%. The EF values were by far less than the mean default EF proposed by the Intergovernmental Panel on Climate Change(IPCC). Our results also showed that N fertilization did not change the seasonal patterns of soil respiration, which were mainly controlled by soil

  1. Organic Matter and Water Addition Enhance Soil Respiration in an Arid Region

    PubMed Central

    Lai, Liming; Wang, Jianjian; Tian, Yuan; Zhao, Xuechun; Jiang, Lianhe; Chen, Xi; Gao, Yong; Wang, Shaoming; Zheng, Yuanrun

    2013-01-01

    Climate change is generally predicted to increase net primary production, which could lead to additional C input to soil. In arid central Asia, precipitation has increased and is predicted to increase further. To assess the combined effects of these changes on soil CO2 efflux in arid land, a two factorial manipulation experiment in the shrubland of an arid region in northwest China was conducted. The experiment used a nested design with fresh organic matter and water as the two controlled parameters. It was found that both fresh organic matter and water enhanced soil respiration, and there was a synergistic effect of these two treatments on soil respiration increase. Water addition not only enhanced soil C emission, but also regulated soil C sequestration by fresh organic matter addition. The results indicated that the soil CO2 flux of the shrubland is likely to increase with climate change, and precipitation played a dominant role in regulating soil C balance in the shrubland of an arid region. PMID:24204907

  2. [Responses of black soil's microbial respiration and community functional diversity to temperature].

    PubMed

    Mi, Liang; Wang, Guang-Hua; Jin, Jian; Liu, Ju-Dong; Liu, Xiao-Bing

    2010-06-01

    Black soil samples were collected from Lishu (43 degrees 20' N, 124 degrees 28' E), Dehui (44 degrees 12' N, 125 degrees 33' E), Hailun (47 degrees 26' N, 126 degrees 38' E), and Bei' an (48 degrees 17' N, 127 degrees 15' E), and an incubation test was conducted to study their microbial respiration and Biolog metabolic functional diversity at 4 degrees C, 15 degrees C, and 28 degrees C. The soil microbial respiration rate was in the order of Bei' an > Hailun > Dehui > Lishu, irrespective of incubation temperature, but the sensitivity of the respiration to the temperature, i. e., Q10 value, differed. The average value of the Q10 for the soils from Lishu, Dehui, Hailun, and Bei'an was 2.72, 3.26, 3.21, and 3.74 in the range of 4 degrees C-15 degrees C, and was 3.29, 2.36, 2.11, and 1.79 in the range of 15 degrees C to 28 degrees C, respectively. The metabolic quotient (qCO2) also differed with incubation temperature, which was in the order of Lishu > Dehui > Bei' an > Hailun at 28 degrees C and of Bei' an > Dehui > Hailun > Lishu at 15 degrees C, but no significant difference was observed at 4 degrees C. Biolog test showed that the substrate richness and metabolic Shannon diversity index of microbial community were higher for the soils from Hailun and Bei' an at 4 degrees C, but higher for those from Lishu and Dehui at 15 degrees C and 28 degrees C. Principal component analysis with Biolog data suggested that the metabolic function of soil microbial community was similar between Bei' an and Hailun, and between Dehui and Lishu. In sum, the responses of black soil's microbial respiration and community functional diversity to temperature varied with latitude, i. e., more sensitive to low temperature in high latitude region, but more sensitive to high temperature in low latitude region.

  3. Soil respiration and photosynthetic uptake of carbon dioxide by ground-cover plants in four ages of jack pine forest

    USGS Publications Warehouse

    Striegl, R.G.; Wickland, K.P.

    2001-01-01

    Soil carbon dioxide (CO2) emission (soil respiration), net CO2 exchange after photosynthetic uptake by ground-cover plants, and soil CO2 concentration versus depth below land surface were measured at four ages of jack pine (Pinus banksiana Lamb.) forest in central Saskatchewan. Soil respiration was smallest at a clear-cut site, largest in an 8-year-old stand, and decreased with stand age in 20-year-old and mature (60-75 years old) stands during May-September 1994 (12.1, 34.6, 31.5, and 24.9 mol C??m-2, respectively). Simulations of soil respiration at each stand based on continuously recorded soil temperature were within one standard deviation of measured flux for 48 of 52 measurement periods, but were 10%-30% less than linear interpolations of measured flux for the season. This was probably due to decreased soil respiration at night modeled by the temperature-flux relationships, but not documented by daytime chamber measurements. CO2 uptake by ground-cover plants ranged from 0 at the clear-cut site to 29, 25, and 9% of total growing season soil respiration at the 8-year, 20-year, and mature stands. CO2 concentrations were as great as 7150 ppmv in the upper 1 m of unsaturated zone and were proportional to measured soil respiration.

  4. Household Anthropogenic Pollutants Against Soil Respiration Erin Murphy EnvironMentors - AggieMentor -Trent Ichiuji University of California Davis / Woodland High School

    NASA Astrophysics Data System (ADS)

    Murphy, E.; Ichiuji, T.

    2013-12-01

    Macroscopic organisms have been largely studied for carbon dioxide release rate and the effect that human development has had on these rates. However, the majority of biomass on Earth is microbes found on the Earth's surface, in the waterways and in soil. As for pollution, a single drop of weak acid is unlikely to kill on the skin of a large animal, yet this could be catastrophic to a colony of microbes. This experiment studied the effect of anthropogenic pollution on soil respiration using toxins that could easily infiltrate our soil and water systems. This project specifically examined common household chemicals in conjunction with Putah Creek soil. The tested toxins were Mobil 1 motor oil, Windex window cleaner, Ajax dish soap, and Dawn antibacterial dish soap. Six samples of Putah Creek soil were collected in jars. Four soil samples were exposed to toxins, while the remaining two were the control and glucose replicates. The control included soil damped by water, while the glucose replicate included both water and glucose. The glucose replicate was included because of its known ability to encourage respiration. A 20 mL NaCl base trap was added to each jar before being sealed. The jars were aerated once a week before titration. The 1.0 N NaCl from each jar of each week was titrated with 0.5 N HCl. The initial prediction for this experiment was that the glucose would raise the respiration levels, and that the control with no glucose would fall. Five weeks of recording the respiration levels confirmed our hypothesis that household toxins are detrimental to the soil microbial community over time. A similar experiment employed heavy metals instead of household toxins. The experiment showed that soil respiration and ATP content were strongly affected by the heavy metal content present in the soil. (Vanhala, Ahtiainen, 1994). This project will raise awareness of the negative effect of improper disposal of seemingly harmless materials. The next step of the project would

  5. Soil respiration patterns and controls in limestone cedar glades

    USGS Publications Warehouse

    Cartwright, Jennifer M.; Hui, Dafeng

    2015-01-01

    Soil depth, SOM, and vegetation cover were important drivers of Rs in limestone cedar glades. Seasonal Rs patterns reflected those for mesic temperate grasslands more than for semi-arid ecosystems, in that Rs primarily tracked temperature for most of the year.

  6. Nitrogen deposition may enhance soil carbon storage via change of soil respiration dynamic during a spring freeze-thaw cycle period

    PubMed Central

    Yan, Guoyong; Xing, Yajuan; Xu, Lijian; Wang, Jianyu; Meng, Wei; Wang, Qinggui; Yu, Jinghua; Zhang, Zhi; Wang, Zhidong; Jiang, Siling; Liu, Boqi; Han, Shijie

    2016-01-01

    As crucial terrestrial ecosystems, temperate forests play an important role in global soil carbon dioxide flux, and this process can be sensitive to atmospheric nitrogen deposition. It is often reported that the nitrogen addition induces a change in soil carbon dioxide emission in growing season. However, the important effects of interactions between nitrogen deposition and the freeze-thaw-cycle have never been investigated. Here we show nitrogen deposition delays spikes of soil respiration and weaken soil respiration. We found the nitrogen addition, time and nitrogen addition×time exerted the negative impact on the soil respiration of spring freeze-thaw periods due to delay of spikes and inhibition of soil respiration (p < 0.001). The values of soil respiration were decreased by 6% (low-nitrogen), 39% (medium-nitrogen) and 36% (high-nitrogen) compared with the control. And the decrease values of soil respiration under medium- and high-nitrogen treatments during spring freeze-thaw-cycle period in temperate forest would be approximately equivalent to 1% of global annual C emissions. Therefore, we show interactions between nitrogen deposition and freeze-thaw-cycle in temperate forest ecosystems are important to predict global carbon emissions and sequestrations. We anticipate our finding to be a starting point for more sophisticated prediction of soil respirations in temperate forests ecosystems. PMID:27358164

  7. Nitrogen deposition may enhance soil carbon storage via change of soil respiration dynamic during a spring freeze-thaw cycle period.

    PubMed

    Yan, Guoyong; Xing, Yajuan; Xu, Lijian; Wang, Jianyu; Meng, Wei; Wang, Qinggui; Yu, Jinghua; Zhang, Zhi; Wang, Zhidong; Jiang, Siling; Liu, Boqi; Han, Shijie

    2016-06-30

    As crucial terrestrial ecosystems, temperate forests play an important role in global soil carbon dioxide flux, and this process can be sensitive to atmospheric nitrogen deposition. It is often reported that the nitrogen addition induces a change in soil carbon dioxide emission in growing season. However, the important effects of interactions between nitrogen deposition and the freeze-thaw-cycle have never been investigated. Here we show nitrogen deposition delays spikes of soil respiration and weaken soil respiration. We found the nitrogen addition, time and nitrogen addition×time exerted the negative impact on the soil respiration of spring freeze-thaw periods due to delay of spikes and inhibition of soil respiration (p < 0.001). The values of soil respiration were decreased by 6% (low-nitrogen), 39% (medium-nitrogen) and 36% (high-nitrogen) compared with the control. And the decrease values of soil respiration under medium- and high-nitrogen treatments during spring freeze-thaw-cycle period in temperate forest would be approximately equivalent to 1% of global annual C emissions. Therefore, we show interactions between nitrogen deposition and freeze-thaw-cycle in temperate forest ecosystems are important to predict global carbon emissions and sequestrations. We anticipate our finding to be a starting point for more sophisticated prediction of soil respirations in temperate forests ecosystems.

  8. Nitrogen deposition may enhance soil carbon storage via change of soil respiration dynamic during a spring freeze-thaw cycle period.

    PubMed

    Yan, Guoyong; Xing, Yajuan; Xu, Lijian; Wang, Jianyu; Meng, Wei; Wang, Qinggui; Yu, Jinghua; Zhang, Zhi; Wang, Zhidong; Jiang, Siling; Liu, Boqi; Han, Shijie

    2016-01-01

    As crucial terrestrial ecosystems, temperate forests play an important role in global soil carbon dioxide flux, and this process can be sensitive to atmospheric nitrogen deposition. It is often reported that the nitrogen addition induces a change in soil carbon dioxide emission in growing season. However, the important effects of interactions between nitrogen deposition and the freeze-thaw-cycle have never been investigated. Here we show nitrogen deposition delays spikes of soil respiration and weaken soil respiration. We found the nitrogen addition, time and nitrogen addition×time exerted the negative impact on the soil respiration of spring freeze-thaw periods due to delay of spikes and inhibition of soil respiration (p < 0.001). The values of soil respiration were decreased by 6% (low-nitrogen), 39% (medium-nitrogen) and 36% (high-nitrogen) compared with the control. And the decrease values of soil respiration under medium- and high-nitrogen treatments during spring freeze-thaw-cycle period in temperate forest would be approximately equivalent to 1% of global annual C emissions. Therefore, we show interactions between nitrogen deposition and freeze-thaw-cycle in temperate forest ecosystems are important to predict global carbon emissions and sequestrations. We anticipate our finding to be a starting point for more sophisticated prediction of soil respirations in temperate forests ecosystems. PMID:27358164

  9. Water organic pollution and eutrophication influence soil microbial processes, increasing soil respiration of estuarine wetlands: site study in jiuduansha wetland.

    PubMed

    Zhang, Yue; Wang, Lei; Hu, Yu; Xi, Xuefei; Tang, Yushu; Chen, Jinhai; Fu, Xiaohua; Sun, Ying

    2015-01-01

    Undisturbed natural wetlands are important carbon sinks due to their low soil respiration. When compared with inland alpine wetlands, estuarine wetlands in densely populated areas are subjected to great pressure associated with environmental pollution. However, the effects of water pollution and eutrophication on soil respiration of estuarine and their mechanism have still not been thoroughly investigated. In this study, two representative zones of a tidal wetland located in the upstream and downstream were investigated to determine the effects of water organic pollution and eutrophication on soil respiration of estuarine wetlands and its mechanism. The results showed that eutrophication, which is a result of there being an excess of nutrients including nitrogen and phosphorus, and organic pollutants in the water near Shang shoal located upstream were higher than in downstream Xia shoal. Due to the absorption and interception function of shoals, there to be more nitrogen, phosphorus and organic matter in Shang shoal soil than in Xia shoal. Abundant nitrogen, phosphorus and organic carbon input to soil of Shang shoal promoted reproduction and growth of some highly heterotrophic metabolic microorganisms such as β-Proteobacteria, γ-Proteobacteria and Acidobacteria which is not conducive to carbon sequestration. These results imply that the performance of pollutant interception and purification function of estuarine wetlands may weaken their carbon sequestration function to some extent.

  10. Water organic pollution and eutrophication influence soil microbial processes, increasing soil respiration of estuarine wetlands: site study in jiuduansha wetland.

    PubMed

    Zhang, Yue; Wang, Lei; Hu, Yu; Xi, Xuefei; Tang, Yushu; Chen, Jinhai; Fu, Xiaohua; Sun, Ying

    2015-01-01

    Undisturbed natural wetlands are important carbon sinks due to their low soil respiration. When compared with inland alpine wetlands, estuarine wetlands in densely populated areas are subjected to great pressure associated with environmental pollution. However, the effects of water pollution and eutrophication on soil respiration of estuarine and their mechanism have still not been thoroughly investigated. In this study, two representative zones of a tidal wetland located in the upstream and downstream were investigated to determine the effects of water organic pollution and eutrophication on soil respiration of estuarine wetlands and its mechanism. The results showed that eutrophication, which is a result of there being an excess of nutrients including nitrogen and phosphorus, and organic pollutants in the water near Shang shoal located upstream were higher than in downstream Xia shoal. Due to the absorption and interception function of shoals, there to be more nitrogen, phosphorus and organic matter in Shang shoal soil than in Xia shoal. Abundant nitrogen, phosphorus and organic carbon input to soil of Shang shoal promoted reproduction and growth of some highly heterotrophic metabolic microorganisms such as β-Proteobacteria, γ-Proteobacteria and Acidobacteria which is not conducive to carbon sequestration. These results imply that the performance of pollutant interception and purification function of estuarine wetlands may weaken their carbon sequestration function to some extent. PMID:25993326

  11. Water Organic Pollution and Eutrophication Influence Soil Microbial Processes, Increasing Soil Respiration of Estuarine Wetlands: Site Study in Jiuduansha Wetland

    PubMed Central

    Zhang, Yue; Wang, Lei; Hu, Yu; Xi, Xuefei; Tang, Yushu; Chen, Jinhai; Fu, Xiaohua; Sun, Ying

    2015-01-01

    Undisturbed natural wetlands are important carbon sinks due to their low soil respiration. When compared with inland alpine wetlands, estuarine wetlands in densely populated areas are subjected to great pressure associated with environmental pollution. However, the effects of water pollution and eutrophication on soil respiration of estuarine and their mechanism have still not been thoroughly investigated. In this study, two representative zones of a tidal wetland located in the upstream and downstream were investigated to determine the effects of water organic pollution and eutrophication on soil respiration of estuarine wetlands and its mechanism. The results showed that eutrophication, which is a result of there being an excess of nutrients including nitrogen and phosphorus, and organic pollutants in the water near Shang shoal located upstream were higher than in downstream Xia shoal. Due to the absorption and interception function of shoals, there to be more nitrogen, phosphorus and organic matter in Shang shoal soil than in Xia shoal. Abundant nitrogen, phosphorus and organic carbon input to soil of Shang shoal promoted reproduction and growth of some highly heterotrophic metabolic microorganisms such as β-Proteobacteria, γ-Proteobacteria and Acidobacteria which is not conducive to carbon sequestration. These results imply that the performance of pollutant interception and purification function of estuarine wetlands may weaken their carbon sequestration function to some extent. PMID:25993326

  12. Do traits of invasive species influence decomposition and soil respiration of disturbed ecosystems?

    NASA Astrophysics Data System (ADS)

    Wells, A. J.; Balster, N. J.

    2009-12-01

    Large-scale landscape disturbances typically alter the terrestrial carbon cycle leading to shifts in pools of soil carbon. Restoration of disturbed landscapes with prairie vegetation has thus been practiced with the intent of increasing carbon accrual in soils. However, since disturbed soils are prone to invasion by non-native invasive species, many ecological restorations have resulted in unexpected outcomes, which may be explained by differences in plant traits such as tissue quality and biomass allocation. Typically, the tissue of invasive species has lower C:N ratios relative to native species, and consequently, faster decomposition rates, which potentially can alter the balance in soil carbon. The primary objective of this research was to compare the effects of native prairie species versus non-native invasive species on the carbon cycling within a novel environment: a recently dewatered basin in southwestern Wisconsin following dam removal. We hypothesized that a higher invasive to native species ratio would result in faster litter decomposition and a higher rate of soil respiration. To test this hypothesis, we seeded newly exposed sediments with native prairie seeds in 2005, annually collected aboveground plant biomass (by species per plot), calculated decomposition rate of native and invasive litter (underneath both canopy types), and measured soil respiration during the growing season of 2009. After four years of seeding, the aboveground biomass of the native vegetation has increased significantly (p < 0.01) from 14.4 to 351 g m-2 while invasive species biomass has decreased from 459 to 296 g m-2. Senesced tissue from mixed native species had a higher C:N ratio, 27:1 (43% C: 1.6% N), than tissue from mixed invasive species, 24:1 (35% C: 1.5% N). However, after 7 months, we found that the rate of decomposition depended on both litter type and plant canopy type (p < 0.01); invasive plant tissue had a slightly faster decomposition rate than the native litter

  13. Parameters of microbial respiration in soils of the impact zone of a mineral fertilizer factory

    NASA Astrophysics Data System (ADS)

    Zhukova, A. D.; Khomyakov, D. M.

    2015-08-01

    The carbon content in the microbial biomass and the microbial production of CO2 (the biological component of soil respiration) were determined in the upper layer (0-10 cm) of soils in the impact zone of the OJSC Voskresensk Mineral Fertilizers, one of the largest factories manufacturing mineral fertilizers in Russia. Statistical characteristics and schematic distribution of the biological parameters in the soil cover of the impact zone were analyzed. The degree of disturbance of microbial communities in the studied objects varied from weak to medium. The maximum value (0.44) was observed on the sampling plot 4 km away from the factory and 0.5 km away from the place of waste (phosphogypsum) storage. Significantly lower carbon content in the microbial biomass and its specific respiration were recorded in the agrosoddy-podzolic soil as compared with the alluvial soil sampled at the same distance from the plant. The effects of potential soil pollutants (fluorine, sulfur, cadmium, and stable strontium) on the characteristics of soil microbial communities were described with reliable regression equations.

  14. Short Term Soil Respiration Response to Fire in a Semi-arid Ecosystem

    NASA Astrophysics Data System (ADS)

    Rozin, A. G.

    2015-12-01

    In the Intermountain West (USA), fire is an important driver of carbon cycling in the environment. Increasing frequency and severity of fires, either through management actions or wildfires, is expected with changing climates in the Western United States. When burning is used as a management tool, it may be beneficial and control the growth of nuisance vegetation, promote the regeneration of grasses and forage species, and reduce hazardous fuel loads to minimize the risk of future wildfires. However, high intensity wildfires often have a negative effect, resulting in a loss of carbon storage and a shift of vegetation communities. This delays recovery of the ecosystem for years or decades and alters the historic fire regime. A 2000 acre prescribed burn in the Reynolds Creek Critical Zone Observatory provided the opportunity to quantify pre and post-burn soil carbon stores and soil carbon losses by heterotrophic respiration. Pre and post-burn soil samples were collected for physical and biogeochemical characterization to quantify substrate availability and possible limitations for heterotrophic respiration. CO2 fluxes were continuously monitored in situ before and immediately after the fire to understand the short-term response of soil respiration to varying burn severities.

  15. Soil respiration contributes substantially to urban carbon fluxes in the greater Boston area.

    PubMed

    Decina, Stephen M; Hutyra, Lucy R; Gately, Conor K; Getson, Jackie M; Reinmann, Andrew B; Short Gianotti, Anne G; Templer, Pamela H

    2016-05-01

    Urban areas are the dominant source of U.S. fossil fuel carbon dioxide (FFCO2) emissions. In the absence of binding international treaties or decisive U.S. federal policy for greenhouse gas regulation, cities have also become leaders in greenhouse gas reduction efforts through climate action plans. These plans focus on anthropogenic carbon flows only, however, ignoring a potentially substantial contribution to atmospheric carbon dioxide (CO2) concentrations from biological respiration. Our aim was to measure the contribution of CO2 efflux from soil respiration to atmospheric CO2 fluxes using an automated CO2 efflux system and to use these measurements to model urban soil CO2 efflux across an urban area. We find that growing season soil respiration is dramatically enhanced in urban areas and represents levels of CO2 efflux of up to 72% of FFCO2 within greater Boston's residential areas, and that soils in urban forests, lawns, and landscaped cover types emit 2.62 ± 0.15, 4.49 ± 0.14, and 6.73 ± 0.26 μmolCO2 m(-2) s(-1), respectively, during the growing season. These rates represent up to 2.2 times greater soil respiration than rates found in nearby rural ecosystems in central Massachusetts (MA), a potential consequence of imported carbon amendments, such as mulch, within a general regime of landowner management. As the scientific community moves rapidly towards monitoring, reporting, and verification of CO2 emissions using ground based approaches and remotely-sensed observations to measure CO2 concentrations, our results show that measurement and modeling of biogenic urban CO2 fluxes will be a critical component for verification of urban climate action plans.

  16. Effect of forest and soil type on microbial biomass carbon and respiration

    NASA Astrophysics Data System (ADS)

    Habashi, Hashem

    2016-09-01

    The aim of study was to evaluate the variation of soil microbial biomass carbon (Cmic) and microbial respiration (MR) in three types soil (Chromic Cambisols, Chromic Luvisols and Eutric Leptosols) of mixed beech forest (Beech- Hornbeam and Beech- Maple). Soil was randomly sampled from 0-10 cm layer (plant litter removed), 90 soil samples were taken. Cmic determined by the fumigation-extraction method and MR by closed bottle method. Soil Corg, Ntot and pH were measured. There are significant differences between the soil types concerning the Cmic content and MR. These parameters were highest in Chromic Cambisols following Chromic Luvisols, while the lowest were in Eutric Leptosols. A similar trend of Corg and Ntot was observed in studied soils. Two-way ANOVA indicated that soil type and forest type have significantly effect on the most soil characteristics. Chromic Cambisols shows a productive soil due to have the maximum Cmic, MR, Corg and Ntot. In Cambisols under Beech- Maple forest the Cmic value and soil C/N ratio were higher compared to Beech-Hornbeam (19.5 and 4.1 mg C g-1, and 16.3 and 3.3, respectively). This fact might be indicated that Maple litter had more easy decomposable organic compounds than Hornbeam. According to regression analysis, 89 and 68 percentage of Cmic variability could explain by soil Corg and Ntot respectively.

  17. Soil warming in a cool-temperate mixed forest with peat soil enhanced heterotrophic and basal respiration rates but Q10 remained unchanged

    NASA Astrophysics Data System (ADS)

    Aguilos, M.; Takagi, K.; Liang, N.; Watanabe, Y.; Goto, S.; Takahashi, Y.; Mukai, H.; Sasa, K.

    2011-07-01

    We conducted soil warming experiment in a cool-temperate forest with peat soil in northern Japan, during the snowless seasons of 2007-2009. Our objective was to determine whether or not the heterotrophic respiration rate and the temperature sensitivity would change by soil warming. We elevated the soil temperature by 3 °C at 5 cm depth by means of overhead infrared heaters and continuously measured soil CO2 fluxes by using a fifteen-channel automated chamber system. Trenching treatment was also carried out to separate heterotrophic respiration and root respiration from the total soil respiration. The fifteen chambers were divided into three groups each with five replications for the control, unwarmed-trenched, and warmed-trenched treatments. We found that heterotrophic respiration contributed 71 % of the total soil respiration with the remaining 29 % accounted to autotrophic respiration. Soil warming enhanced heterotrophic respiration by 74 % (mean 6.11 ± 3.07 S.D. μmol m-2 s-1) as compared to the unwarmed-trenched treatment (mean 3.52 ± 1.74 μmol m-2 s-1). Soil CO2 efflux, however, was weakly correlated with soil moisture, probably because the volumetric soil moisture (33-46 %) was within a plateau region for root and microbial activities. The enhancement in heterotrophic respiration with soil warming in our study suggests that global warming will accelerate the loss of carbon from forested peatlands more seriously than other upland forest soils. On the other hand, soil warming did not cause significant change in the temperature sensitivity, Q10, (2.79 and 2.74 determined using hourly efflux data for unwarmed- and warmed-trenched, respectively), but increased their basal respiration rate at 0 °C (0.93 and 1.21 μmol m-2 s-1, respectively). Results suggest that if we predict the soil heterotrophic respiration rate in future warmer environment using the current relationship between soil temperature and heterotrophic respiration, the rate can be underestimated.

  18. Separating Autotrophic and Heterotrophic Contributions to Soil Respiration in Maize-Based Agroecosystems Using Stable Carbon Isotope Ratio Mass Spectrometry.

    NASA Astrophysics Data System (ADS)

    Amos, B.; Walters, D. T.; Madhavan, S.; Arkebauer, T. J.; Scoby, D. L.

    2005-12-01

    Any effort to establish a carbon budget for a growing crop by means of a thorough accounting of all C sources and sinks will require the ability to discriminate between autotrophic and heterotrophic contributions to soil surface CO2 flux. Autotrophic soil respiration (Ra) is defined as combined root respiration and the respiration of soil microorganisms residing in the rhizosphere and using root-derived carbohydrates as an energy source, while heterotrophic respiration (Rh) is defined as the respiration of soil microorganisms and macroorganisms not directly under the influence of the live root system and using SOM as an energy source. We partition soil surface CO2 flux into its autotrophic and heterotrophic components by combining root exclusion with stable carbon isotope techniques in production scale (~65 ha) maize-based agroecosystems. After flux measurements, small chambers are placed on collars in both root excluded shields and in non-root excluded soil, ambient headspace CO2 is removed using a soda lime trap, and soil-respired C is allowed to collect in the chambers. Soil respiration samples are then collected in 12mL evacuated exetainers and analyzed for δ13C by means of a Finnigan Delta-S isotope ratio mass spectrometer interfaced with a Thermo Finnigan GasBench II and a cryogenic trap to increase CO2 concentration. These δ13C measurements were made throughout the 2005 growing season in maize fields representing three agroecosystems: irrigated continuous maize, irrigated maize-soybean rotation, and rainfed maize soybean rotation. Estimates of autotrophic and heterotrophic soil respiration along with other results of this study will be presented.

  19. Microbial Community Composition Affects Soil Fungistasis†

    PubMed Central

    de Boer, Wietse; Verheggen, Patrick; Klein Gunnewiek, Paulien J. A.; Kowalchuk, George A.; van Veen, Johannes A.

    2003-01-01

    Most soils inhibit fungal germination and growth to a certain extent, a phenomenon known as soil fungistasis. Previous observations have implicated microorganisms as the causal agents of fungistasis, with their action mediated either by available carbon limitation (nutrient deprivation hypothesis) or production of antifungal compounds (antibiosis hypothesis). To obtain evidence for either of these hypotheses, we measured soil respiration and microbial numbers (as indicators of nutrient stress) and bacterial community composition (as an indicator of potential differences in the composition of antifungal components) during the development of fungistasis. This was done for two fungistatic dune soils in which fungistasis was initially fully or partly relieved by partial sterilization treatment or nutrient addition. Fungistasis development was measured as restriction of the ability of the fungi Chaetomium globosum, Fusarium culmorum, Fusarium oxysporum, and Trichoderma harzianum to colonize soils. Fungistasis did not always reappear after soil treatments despite intense competition for carbon, suggesting that microbial community composition is important in the development of fungistasis. Both microbial community analysis and in vitro antagonism tests indicated that the presence of pseudomonads might be essential for the development of fungistasis. Overall, the results lend support to the antibiosis hypothesis. PMID:12571002

  20. Biophysical controls on rhizospheric and heterotrophic components of soil respiration in a boreal black spruce stand.

    PubMed

    Gaumont-Guay, David; Black, T Andrew; Barr, Alan G; Jassal, Rachhpal S; Nesic, Zoran

    2008-02-01

    We conducted a root-exclusion experiment in a 125-year-old boreal black spruce (Picea mariana (Mill.) BSP) stand in 2004 to quantify the physical and biological controls on temporal dynamics of the rhizospheric (R(r)) and heterotrophic (R(h)) components of soil respiration (R(s)). Annual R(r), R(h) and estimated moss respiration were 285, 269 and 57 g C m(-2) year(-1), respectively, which accounted for 47, 44 and 9% of R(s) (611 g C m(-2) year(-1)), respectively. A gradual transition from R(h)-dominated (winter, spring and fall) to R(r)-dominated (summer) respiration was observed during the year. Soil thawing in spring and the subsequent increase in soil water content (theta) induced a small and sustained increase in R(h) but had no effect on R(r). During the remainder of the growing season, no effect of theta was observed on either component of R(s). Both components increased exponentially with soil temperature (T(s)) during the growing season, but R(r) showed greater temperature sensitivity than R(h) (Q(10) of 4.0 and 3.0, respectively). Temperature-normalized variations in R(r) were highly correlated with eddy covariance estimates of gross ecosystem photosynthesis, and the correlation was greatest when R(r) was lagged by 24 days. Within diurnal cycles, variations in T(s) were highly coupled to variations in R(h) but were significantly decoupled from R(r). The patterns observed at both time scales strongly suggest that the flow of photosynthates to the rhizosphere is a key driver of belowground respiration processes but that photosynthate supply may control these processes in several ways. PMID:18055427

  1. Bayesian multimodel inference of soil microbial respiration models: Theory, application and future prospective

    NASA Astrophysics Data System (ADS)

    Elshall, A. S.; Ye, M.; Niu, G. Y.; Barron-Gafford, G.

    2015-12-01

    Models in biogeoscience involve uncertainties in observation data, model inputs, model structure, model processes and modeling scenarios. To accommodate for different sources of uncertainty, multimodal analysis such as model combination, model selection, model elimination or model discrimination are becoming more popular. To illustrate theoretical and practical challenges of multimodal analysis, we use an example about microbial soil respiration modeling. Global soil respiration releases more than ten times more carbon dioxide to the atmosphere than all anthropogenic emissions. Thus, improving our understanding of microbial soil respiration is essential for improving climate change models. This study focuses on a poorly understood phenomena, which is the soil microbial respiration pulses in response to episodic rainfall pulses (the "Birch effect"). We hypothesize that the "Birch effect" is generated by the following three mechanisms. To test our hypothesis, we developed and assessed five evolving microbial-enzyme models against field measurements from a semiarid Savannah that is characterized by pulsed precipitation. These five model evolve step-wise such that the first model includes none of these three mechanism, while the fifth model includes the three mechanisms. The basic component of Bayesian multimodal analysis is the estimation of marginal likelihood to rank the candidate models based on their overall likelihood with respect to observation data. The first part of the study focuses on using this Bayesian scheme to discriminate between these five candidate models. The second part discusses some theoretical and practical challenges, which are mainly the effect of likelihood function selection and the marginal likelihood estimation methods on both model ranking and Bayesian model averaging. The study shows that making valid inference from scientific data is not a trivial task, since we are not only uncertain about the candidate scientific models, but also about

  2. Disentangling drought-induced variation in ecosystem and soil respiration using stable carbon isotopes.

    PubMed

    Unger, Stephan; Máguas, Cristina; Pereira, João S; Aires, Luis M; David, Teresa S; Werner, Christiane

    2010-08-01

    Combining C flux measurements with information on their isotopic composition can yield a process-based understanding of ecosystem C dynamics. We studied the variations in both respiratory fluxes and their stable C isotopic compositions (delta(13)C) for all major components (trees, understory, roots and soil microorganisms) in a Mediterranean oak savannah during a period with increasing drought. We found large drought-induced and diurnal dynamics in isotopic compositions of soil, root and foliage respiration (delta(13)C(res)). Soil respiration was the largest contributor to ecosystem respiration (R (eco)), exhibiting a depleted isotopic signature and no marked variations with increasing drought, similar to ecosystem respired delta(13)CO(2), providing evidence for a stable C-source and minor influence of recent photosynthate from plants. Short-term and diurnal variations in delta(13)C(res) of foliage and roots (up to 8 and 4 per thousand, respectively) were in agreement with: (1) recent hypotheses on post-photosynthetic fractionation processes, (2) substrate changes with decreasing assimilation rates in combination with increased respiratory demand, and (3) decreased phosphoenolpyruvate carboxylase activity in drying roots, while altered photosynthetic discrimination was not responsible for the observed changes in delta(13)C(res). We applied a flux-based and an isotopic flux-based mass balance, yielding good agreement at the soil scale, while the isotopic mass balance at the ecosystem scale was not conserved. This was mainly caused by uncertainties in Keeling plot intercepts at the ecosystem scale due to small CO(2) gradients and large differences in delta(13)C(res) of the different component fluxes. Overall, stable isotopes provided valuable new insights into the drought-related variations of ecosystem C dynamics, encouraging future studies but also highlighting the need of improved methodology to disentangle short-term dynamics of isotopic composition of R (eco).

  3. Remote sensing-based estimation of annual soil respiration at two contrasting forest sites

    SciTech Connect

    Gu, Lianhong; Huang, Ni; Black, T. Andrew; Wang, Li; Niu, Zheng

    2015-11-23

    Soil respiration (Rs), an important component of the global carbon cycle, can be estimated using remotely sensed data, but the accuracy of this technique has not been thoroughly investigated. In this article, we proposed a methodology for the remote estimation of annual Rs at two contrasting FLUXNET forest sites (a deciduous broadleaf forest and an evergreen needleleaf forest).

  4. Responses of soil respiration to elevated CO[sub 2] in two California grassland ecosystems

    SciTech Connect

    Luo, Y.; Jackson, R.B.; Field, C.B.; Mooney, H.A. )

    1994-06-01

    Estimates of soil respiration (SR) in current and elevated CO[sub 2] are critical for predicting future global carbon budgets. We measured SR in two California grassland ecosystems (sandstone and serpentine) growing at ambient and ambient+350 ppm CO[sub 2]. SR was higher in elevated CO[sub 2] for both ecosystems in the field, but differences were not significant. At peak plant growth, SR was approximately 6 [mu]mol m[sup [minus]2]s[sup [minus]1] in elevated CO[sub 2] and 5 [mu]mol m[sup [minus]2] s[sup [minus]1] in ambient CO[sub 2] for both ecosystems. We also examined soil respiration in monocultures of 7 grassland species grown in microecosystems (10-cm diameter by 1-m deep tubes). SR was approximately 2 [mu]mol m[sup [minus]2]s[sup [minus]1] for Plantago, Bromus, Hemizona, and Calycadenia and 7 [minus] 8 [mu]mol m[sup [minus]2]s[sup [minus]2] for Lolium, Avena, and Vulpia. Elevated CO[sub 2] significantly increased soil respiration by 20-30% in Bromus, Hemizonia and Lolium monocultures. SR was significantly correlated with total plant biomass as averaged across all species.

  5. Spatial Variability of Stem Wood and Soil Respiration in Tropical Forests

    NASA Astrophysics Data System (ADS)

    Lopes, E.; Varner, R.; Crill, P.; Keller, M.; Czepiel, P.

    2002-12-01

    It is commonly accepted that stem wood respiration and soil surface/atmosphere trace gases fluxes are spatially highly variable. However there are few studies that attempt to quantify this variability. Manual measurements of soil and stem wood CO2 fluxes can be useful in determining spatial heterogeneity. During the periods of March 14 to 16 and June 7 to 13 we measured stem wood respiration from a wet tropical forest in La Selva, Costa Rica; and between July 16 and 27, 2002 we measured soil CO2 exchanges in a tropical forest located near Santarem, Para, Brazil. Measurements were obtained using manual chamber systems. Fluxes were measured in chamber headspace air using a pump and an open \\- path infrared gas analyzer. Generally, fluxes ranged between 2 and 6 μmol m-2 s-1 for soil and 0.13 and 6.4 æmol m-2 s-1 for stem wood during the sampling periods. The average flux of all points was 4.6 +/-1.7 μmol m-2s-1 for soil and 1.8 +/-1.14μmol m-2s-1 for stem wood. Existent automated systems installed at these sites have showed a range of soil CO2 flux values between 1.5 and 6 \\mumol m^{-2} s^{-1} in Santarem site, and 0.001 and 8.95 μ mol m-2 s-1 for stem wood respiration in La Selva site for the same period of year.

  6. Patterns and Drivers of Soil Respiration under Long-Term Citrus reticulate in Southern China.

    PubMed

    Zhang, Yan-Jie; Zhang, Su-Yan; Yang, Jie; Yan, Yue; Fu, Xiang-Ping; Lu, Shun-Bao

    2015-01-01

    Soil respiration (Rs) is a major source of carbon emission in terrestrial ecosystems. Despite the fact that the influence of land use practice on Rs has been widely studied, the patterns and drivers on Rs of Citrus reticulata cultivation, a worldwide land use practice are unclear. In this current study, we investigated the influence of long-term cultivation of Citrus reticulata (CO) and of CO intercropped with soybean (CB) on soil nutrients, water availability, and Rs in southern China. Results indicated that after 21 years of cultivation, CO and CB significantly increased total soil carbon (TC), total soil nitrogen (TN), and soil organic matter (OM) at 0-20 cm and 20-40 cm, both at upslope and downslope compared with bare soil (CK). However, soil moisture (SM), dissolved organic carbon (DOC), and microbial biomass carbon (MBC) decreased under CB. In addition, no significant variation was found in soil pH between CK, CO, and CB. Across incubation time (56 days), Rs decreased exponentially with incubation time and CB showed the highest Rs rate irrespective of soil depth or topography. Linear regression further showed TC and TN as the two major factors influencing Rs upslope, while DOC was the dominant factor in regulating Rs downslope. These findings demonstrated that long-term cultivation of citrus significantly changed soil nutrients, water availability, and Rs rate. PMID:26368561

  7. Precipitation regime shift enhanced the rain pulse effect on soil respiration in a semi-arid steppe.

    PubMed

    Yan, Liming; Chen, Shiping; Xia, Jianyang; Luo, Yiqi

    2014-01-01

    The effect of resource pulses, such as rainfall events, on soil respiration plays an important role in controlling grassland carbon balance, but how shifts in long-term precipitation regime regulate rain pulse effect on soil respiration is still unclear. We first quantified the influence of rainfall event on soil respiration based on a two-year (2006 and 2009) continuously measured soil respiration data set in a temperate steppe in northern China. In 2006 and 2009, soil carbon release induced by rainfall events contributed about 44.5% (83.3 g C m(-2)) and 39.6% (61.7 g C m(-2)) to the growing-season total soil respiration, respectively. The pulse effect of rainfall event on soil respiration can be accurately predicted by a water status index (WSI), which is the product of rainfall event size and the ratio between antecedent soil temperature to moisture at the depth of 10 cm (r2 = 0.92, P<0.001) through the growing season. It indicates the pulse effect can be enhanced by not only larger individual rainfall event, but also higher soil temperature/moisture ratio which is usually associated with longer dry spells. We then analyzed a long-term (1953-2009) precipitation record in the experimental area. We found both the extreme heavy rainfall events (>40 mm per event) and the long dry-spells (>5 days) during the growing seasons increased from 1953-2009. It suggests the shift in precipitation regime has increased the contribution of rain pulse effect to growing-season total soil respiration in this region. These findings highlight the importance of incorporating precipitation regime shift and its impacts on the rain pulse effect into the future predictions of grassland carbon cycle under climate change.

  8. Precipitation Regime Shift Enhanced the Rain Pulse Effect on Soil Respiration in a Semi-Arid Steppe

    PubMed Central

    Yan, Liming; Chen, Shiping; Xia, Jianyang; Luo, Yiqi

    2014-01-01

    The effect of resource pulses, such as rainfall events, on soil respiration plays an important role in controlling grassland carbon balance, but how shifts in long-term precipitation regime regulate rain pulse effect on soil respiration is still unclear. We first quantified the influence of rainfall event on soil respiration based on a two-year (2006 and 2009) continuously measured soil respiration data set in a temperate steppe in northern China. In 2006 and 2009, soil carbon release induced by rainfall events contributed about 44.5% (83.3 g C m−2) and 39.6% (61.7 g C m−2) to the growing-season total soil respiration, respectively. The pulse effect of rainfall event on soil respiration can be accurately predicted by a water status index (WSI), which is the product of rainfall event size and the ratio between antecedent soil temperature to moisture at the depth of 10 cm (r2 = 0.92, P<0.001) through the growing season. It indicates the pulse effect can be enhanced by not only larger individual rainfall event, but also higher soil temperature/moisture ratio which is usually associated with longer dry spells. We then analyzed a long-term (1953–2009) precipitation record in the experimental area. We found both the extreme heavy rainfall events (>40 mm per event) and the long dry-spells (>5 days) during the growing seasons increased from 1953–2009. It suggests the shift in precipitation regime has increased the contribution of rain pulse effect to growing-season total soil respiration in this region. These findings highlight the importance of incorporating precipitation regime shift and its impacts on the rain pulse effect into the future predictions of grassland carbon cycle under climate change. PMID:25093573

  9. A rapid in situ respiration test for measuring aerobic biodegradation rates of hydrocarbons in soil.

    PubMed

    Hinchee, R E; Ong, S K

    1992-10-01

    An in situ test method to measure the aerobic biodegradation rates of hydrocarbons in contaminated soil is presented. The test method provides an initial assessment of bioventing as a remediation technology for hydrocarbon-contaminated soil. The in situ respiration test consists of ventilating the contaminated soil of the unsaturated zone with air and periodically monitoring the depletion of oxygen (O2) and production of carbon dioxide (CO2) over time after the air is turned off. The test is simple to implement and generally takes about four to five days to complete. The test was applied at eight hydrocarbon-contaminated sites of different geological and climatic conditions. These sites were contaminated with petroleum products or petroleum fuels, except for two sites where the contaminants were primarily polycyclic aromatic hydrocarbons. Oxygen utilization rates for the eight sites ranged from 0.02 to 0.99 percent O2/hour. Estimated biodegradation rates ranged from 0.4 to 19 mg/kg of soil/day. These rates were similar to the biodegradation rates obtained from field and pilot studies using mass balance methods. Estimated biodegradation rates based on O2 utilization were generally more reliable (especially for alkaline soils) than rates based on CO2 production. CO2 produced from microbial respiration was probably converted to carbonate under alkaline conditions.

  10. Landscape Soil Respiration Fluxes are Related to Leaf Area Index, Stand Height and Density, and Soil Nitrogen in Rocky Mountain Subalpine Forests

    NASA Astrophysics Data System (ADS)

    Berryman, E.; Bradford, J. B.; Hawbaker, T. J.; Birdsey, R.; Ryan, M. G.

    2015-12-01

    There is a recent multi-agency push for accurate assessments of terrestrial carbon stocks and fluxes in the United States. Assessing the state of the carbon cycle in the US requires estimates of stocks and fluxes at large spatial scales. Such assessments are difficult, especially for soil respiration, which dominates ecosystem respiration and is notoriously highly variable over space and time. Here, we report three consecutive years of measurement of soil respiration fluxes in three 1 km2 subalpine forest landscapes: Fraser Experimental Forest (Colorado), Glacier Lakes Ecosystems Experimental Site ("GLEES", Wyoming), and Niwot Ridge (Colorado). Plots were established following the protocol of the US Forest Service's Forest Inventory and Analysis (FIA) Program. Clusters of plots were distributed across the landscape in a 0.25 km grid pattern. From 2004 through 2006, measurements of soil respiration were made once monthly during the growing season and twice during snowpack coverage for each year. Annual cumulative soil respiration was 6.10 (+/- 0.21) Mg ha-1y-1 for Fraser, 6.55 (+/- 0.27) Mg ha-1y-1 for GLEES, and 6.97 (+/- 0.20) Mg ha-1y-1 for Niwot. Variability in annual cumulative soil respiration varied by less than 20% among the three subalpine forests, despite differences in terrain, climate, disturbance history and anthropogenic nitrogen deposition. We quantified the relationship between respiration fluxes and commonly-measured forest properties and found that soil respiration was nonlinearly related to leaf area index, peaking around 2.5 m2m-2 then slowly declining. Annual litterfall (FA) was subtracted from soil respiration (FR) to calculate total belowground carbon flux (TBCF), which declined with increasing tree height, density and soil nitrogen. This landscape analysis of soil respiration confirmed experimentally-derived principles governing carbon fluxes in forests: as trees age and get taller, and in high-fertility areas, carbon flux to roots declines

  11. Spartina alterniflora invasion alters soil microbial community composition and microbial respiration following invasion chronosequence in a coastal wetland of China

    PubMed Central

    Yang, Wen; Jeelani, Nasreen; Leng, Xin; Cheng, Xiaoli; An, Shuqing

    2016-01-01

    The role of exotic plants in regulating soil microbial community structure and activity following invasion chronosequence remains unclear. We investigated soil microbial community structure and microbial respiration following Spartina alterniflora invasion in a chronosequence of 6-, 10-, 17-, and 20-year-old by comparing with bare flat in a coastal wetland of China. S. alterniflora invasion significantly increased soil moisture and salinity, the concentrations of soil water-soluble organic carbon and microbial biomass carbon (MBC), the quantities of total and various types of phospholipid fatty acids (PLFAs), the fungal:bacterial PLFAs ratio and cumulative microbial respiration compared with bare flat. The highest MBC, gram-negative bacterial and saturated straight-chain PLFAs were found in 10-year-old S. alterniflora soil, while the greatest total PLFAs, bacterial and gram-positive bacterial PLFAs were found in 10- and 17-year-old S. alterniflora soils. The monounsaturated:branched PLFAs ratio declined, and cumulative microbial respiration on a per-unit-PLFAs increased following S. alterniflora invasion in the chronosequence. Our results suggest that S. alterniflora invasion significantly increased the biomass of soil various microbial groups and microbial respiration compared to bare flat soil by increasing soil available substrate, and modifying soil physiochemical properties. Soil microbial community reached the most enriched condition in the 10-year-old S. alterniflora community. PMID:27241173

  12. Spartina alterniflora invasion alters soil microbial community composition and microbial respiration following invasion chronosequence in a coastal wetland of China.

    PubMed

    Yang, Wen; Jeelani, Nasreen; Leng, Xin; Cheng, Xiaoli; An, Shuqing

    2016-01-01

    The role of exotic plants in regulating soil microbial community structure and activity following invasion chronosequence remains unclear. We investigated soil microbial community structure and microbial respiration following Spartina alterniflora invasion in a chronosequence of 6-, 10-, 17-, and 20-year-old by comparing with bare flat in a coastal wetland of China. S. alterniflora invasion significantly increased soil moisture and salinity, the concentrations of soil water-soluble organic carbon and microbial biomass carbon (MBC), the quantities of total and various types of phospholipid fatty acids (PLFAs), the fungal:bacterial PLFAs ratio and cumulative microbial respiration compared with bare flat. The highest MBC, gram-negative bacterial and saturated straight-chain PLFAs were found in 10-year-old S. alterniflora soil, while the greatest total PLFAs, bacterial and gram-positive bacterial PLFAs were found in 10- and 17-year-old S. alterniflora soils. The monounsaturated:branched PLFAs ratio declined, and cumulative microbial respiration on a per-unit-PLFAs increased following S. alterniflora invasion in the chronosequence. Our results suggest that S. alterniflora invasion significantly increased the biomass of soil various microbial groups and microbial respiration compared to bare flat soil by increasing soil available substrate, and modifying soil physiochemical properties. Soil microbial community reached the most enriched condition in the 10-year-old S. alterniflora community. PMID:27241173

  13. Spartina alterniflora invasion alters soil microbial community composition and microbial respiration following invasion chronosequence in a coastal wetland of China

    NASA Astrophysics Data System (ADS)

    Yang, Wen; Jeelani, Nasreen; Leng, Xin; Cheng, Xiaoli; An, Shuqing

    2016-05-01

    The role of exotic plants in regulating soil microbial community structure and activity following invasion chronosequence remains unclear. We investigated soil microbial community structure and microbial respiration following Spartina alterniflora invasion in a chronosequence of 6-, 10-, 17-, and 20-year-old by comparing with bare flat in a coastal wetland of China. S. alterniflora invasion significantly increased soil moisture and salinity, the concentrations of soil water-soluble organic carbon and microbial biomass carbon (MBC), the quantities of total and various types of phospholipid fatty acids (PLFAs), the fungal:bacterial PLFAs ratio and cumulative microbial respiration compared with bare flat. The highest MBC, gram-negative bacterial and saturated straight-chain PLFAs were found in 10-year-old S. alterniflora soil, while the greatest total PLFAs, bacterial and gram-positive bacterial PLFAs were found in 10- and 17-year-old S. alterniflora soils. The monounsaturated:branched PLFAs ratio declined, and cumulative microbial respiration on a per-unit-PLFAs increased following S. alterniflora invasion in the chronosequence. Our results suggest that S. alterniflora invasion significantly increased the biomass of soil various microbial groups and microbial respiration compared to bare flat soil by increasing soil available substrate, and modifying soil physiochemical properties. Soil microbial community reached the most enriched condition in the 10-year-old S. alterniflora community.

  14. Multi-Year Lags between Forest Browning and Soil Respiration at High Northern Latitudes

    SciTech Connect

    Bond-Lamberty, Benjamin; Bunn, Andrew G.; Thomson, Allison M.

    2012-11-26

    High-latitude northern ecosystems are experiencing rapid climate changes, and represent a large potential climate feedback because of their high soil carbon densities and shifting disturbance regimes. A significant carbon flow from these ecosystems is soil respiration (RS, the flow of carbon dioxide, generated by plant roots and soil fauna, from the soil surface to atmosphere), and any change in the high-latitude carbon cycle might thus be reflected in RS observed in the field. This study used two variants of a machine-learning algorithm and least squares regression to examine how remotely-sensed canopy greenness (NDVI), climate, and other variables are coupled to annual RS based on 105 observations from 64 circumpolar sites in a global database. The addition of NDVI roughly doubled model performance, with the best-performing models explaining ~62% of observed RS variability

  15. Soil respiration in Tibetan alpine grasslands: belowground biomass and soil moisture, but not soil temperature, best explain the large-scale patterns.

    PubMed

    Geng, Yan; Wang, Yonghui; Yang, Kuo; Wang, Shaopeng; Zeng, Hui; Baumann, Frank; Kuehn, Peter; Scholten, Thomas; He, Jin-Sheng

    2012-01-01

    The Tibetan Plateau is an essential area to study the potential feedback effects of soils to climate change due to the rapid rise in its air temperature in the past several decades and the large amounts of soil organic carbon (SOC) stocks, particularly in the permafrost. Yet it is one of the most under-investigated regions in soil respiration (Rs) studies. Here, Rs rates were measured at 42 sites in alpine grasslands (including alpine steppes and meadows) along a transect across the Tibetan Plateau during the peak growing season of 2006 and 2007 in order to test whether: (1) belowground biomass (BGB) is most closely related to spatial variation in Rs due to high root biomass density, and (2) soil temperature significantly influences spatial pattern of Rs owing to metabolic limitation from the low temperature in cold, high-altitude ecosystems. The average daily mean Rs of the alpine grasslands at peak growing season was 3.92 µmol CO(2) m(-2) s(-1), ranging from 0.39 to 12.88 µmol CO(2) m(-2) s(-1), with average daily mean Rs of 2.01 and 5.49 µmol CO(2) m(-2) s(-1) for steppes and meadows, respectively. By regression tree analysis, BGB, aboveground biomass (AGB), SOC, soil moisture (SM), and vegetation type were selected out of 15 variables examined, as the factors influencing large-scale variation in Rs. With a structural equation modelling approach, we found only BGB and SM had direct effects on Rs, while other factors indirectly affecting Rs through BGB or SM. Most (80%) of the variation in Rs could be attributed to the difference in BGB among sites. BGB and SM together accounted for the majority (82%) of spatial patterns of Rs. Our results only support the first hypothesis, suggesting that models incorporating BGB and SM can improve Rs estimation at regional scale.

  16. Soil Respiration in Tibetan Alpine Grasslands: Belowground Biomass and Soil Moisture, but Not Soil Temperature, Best Explain the Large-Scale Patterns

    PubMed Central

    Geng, Yan; Wang, Yonghui; Yang, Kuo; Wang, Shaopeng; Zeng, Hui; Baumann, Frank; Kuehn, Peter; Scholten, Thomas; He, Jin-Sheng

    2012-01-01

    The Tibetan Plateau is an essential area to study the potential feedback effects of soils to climate change due to the rapid rise in its air temperature in the past several decades and the large amounts of soil organic carbon (SOC) stocks, particularly in the permafrost. Yet it is one of the most under-investigated regions in soil respiration (Rs) studies. Here, Rs rates were measured at 42 sites in alpine grasslands (including alpine steppes and meadows) along a transect across the Tibetan Plateau during the peak growing season of 2006 and 2007 in order to test whether: (1) belowground biomass (BGB) is most closely related to spatial variation in Rs due to high root biomass density, and (2) soil temperature significantly influences spatial pattern of Rs owing to metabolic limitation from the low temperature in cold, high-altitude ecosystems. The average daily mean Rs of the alpine grasslands at peak growing season was 3.92 µmol CO2 m−2 s−1, ranging from 0.39 to 12.88 µmol CO2 m−2 s−1, with average daily mean Rs of 2.01 and 5.49 µmol CO2 m−2 s−1 for steppes and meadows, respectively. By regression tree analysis, BGB, aboveground biomass (AGB), SOC, soil moisture (SM), and vegetation type were selected out of 15 variables examined, as the factors influencing large-scale variation in Rs. With a structural equation modelling approach, we found only BGB and SM had direct effects on Rs, while other factors indirectly affecting Rs through BGB or SM. Most (80%) of the variation in Rs could be attributed to the difference in BGB among sites. BGB and SM together accounted for the majority (82%) of spatial patterns of Rs. Our results only support the first hypothesis, suggesting that models incorporating BGB and SM can improve Rs estimation at regional scale. PMID:22509373

  17. [Effects of different mulching measures on winter wheat field soil respiration in Loess Plateau dry land region].

    PubMed

    Guan, Qing; Wang, Jun; Song, Shu-Ya; Liu, Wen-Zhao

    2011-06-01

    A field experiment was conducted to study the effects of different mulching measures on the diurnal and seasonal variations of winter wheat field soil respiration in dry land region of Loess Plateau. Four treatments were installed, i. e., 300 kg x hm(-2) straw mulching (M300), 600 kg x hm(-2) straw mulching (M600), plastic film mulching (PM), and no mulching (CK). In all treatments, the soil respiration rate had a decreasing trend from autumn to winter, but increased rapidly after winter and peaked at jointing stage. Comparing with CK, treatments mulching promoted the soil respiration obviously from wintering to maturing stage, with significant differences between treatment PM and the others. The average soil respiration rate in treatments M300, and M600 in whole growth period was 1. 52 micromol CO2 x m(-2) x s(-1) and 1. 47 micromol CO2 x m(-2) x s(-1), being 10. 2% and 6.6% higher than the CK (1.38 micromol CO2 x m(-2) s(-1)) , respectively, and that in treatment PM was 3. 63 micromol CO2 x m(-2) x s(-1), 163% higher than CK. The diurnal variation of soil respiration rate in CK and in M300 and M600 presented a single peak curve and peaked at 12:00 and 14:00, respectively, but for PM treatment, the diurnal variation of soil respiration rate was similar with that in CK at jointing stage while presented a bimodal curve at maturing stage, with the peaks at 12:00 and 16:00, respectively. Soil respiration rate had an exponential correlation with soil temperature, and a parabolic correlation with soil moisture.

  18. Field-based cavity ring-down spectrometry of δ¹³C in soil-respired CO₂.

    PubMed

    Munksgaard, Niels C; Davies, Kalu; Wurster, Chris M; Bass, Adrian M; Bird, Michael I

    2013-06-01

    Measurement of soil-respired CO₂ at high temporal resolution and sample density is necessary to accurately identify sources and quantify effluxes of soil-respired CO₂. A portable sampling device for the analysis of δ(13)C values in the field is described herein. CO₂ accumulated in a soil chamber was batch sampled sequentially in four gas bags and analysed by Wavelength-Scanned Cavity Ring-down Spectrometry (WS-CRDS). A Keeling plot (1/[CO₂] versus δ(13)C) was used to derive δ(13)C values of soil-respired CO₂. Calibration to the δ(13)C Vienna Peedee Belemnite scale was by analysis of cylinder CO₂ and CO₂ derived from dissolved carbonate standards. The performance of gas-bag analysis was compared to continuous analysis where the WS-CRDS analyser was connected directly to the soil chamber. Although there are inherent difficulties in obtaining absolute accuracy data for δ(13)C values in soil-respired CO₂, the similarity of δ(13)C values obtained for the same test soil with different analytical configurations indicated that an acceptable accuracy of the δ(13)C data were obtained by the WS-CRDS techniques presented here. Field testing of a variety of tropical soil/vegetation types, using the batch sampling technique yielded δ(13)C values for soil-respired CO₂ related to the dominance of either C₃ (tree, δ(13)C=-27.8 to-31.9 ‰) or C₄ (tropical grass, δ(13)C=-9.8 to-13.6 ‰) photosynthetic pathways in vegetation at the sampling sites. Standard errors of the Keeling plot intercept δ(13)C values of soil-respired CO₂ were typically<0.4 ‰ for analysis of soils with high CO₂ efflux (>7-9 μmol m(-2) s(-1)).

  19. [Spatial Heterogeneity of Soil Respiration in a Larch Plantation of North China at Different Sampling Scales].

    PubMed

    Yan, Jun-xia; Liang, Ya-nan; Li, Hong-jian; Li, Jun-jian

    2015-12-01

    Based on observations of soil respiration rate (Rs) and both biotic and abiotic factors in Pangquangou Nature Reserve at three sampling scales (4, 2, and 1 m), we studied the spatial heterogeneity of Rs and the factors, and analyzed impacts of soil temperature at the 5, 10 and 15 cm depth (T5, T10, T15), soil moisture over the depth of 0-10 cm (Ws), and soil total nitrogen (N), soil total organic carbon (C), ratio of carbon and nitrogen (C/N), soil total sulfur (S), litter fall mass (Lw) and litter fall moisture (Lm) on the spatial heterogeneity of Rs, respectively. We also calculated the minimum sampling number of all the factors at different confidence levels and under the responding estimation accuracy. The results showed that: (1) the spatial heterogeneity of C/N at 4 m sampling scale, Ws at 2 m sampling scale and T10, T15 at 1 m sampling scale had low variability, while the spatial variation of Rs and other related factors had medium variability. Coefficients of variation of Rs, C/N and S decreased with the increase of the sampling scales, but those of N, C, Ws, T₅, T₁₀, T₁₅, Lw and Lm showed contrary trend; (2) the spatial autocorrelation of Rs, Ws, T₅, T₁₀, T₁₅, Lw and Lm decreased with the decrease of sampling scales but the spatial autocorrelation of C, N, C/N increased with the decrease of sampling scales, and the spatial autocorrelation of S decreased with the decrease of the sampling scales at initial stage and then increased; (3) the key factors that influenced the spatial heterogeneity of soil respiration were different at different sampling scales. Soil temperature was the key factor influencing the spatial heterogeneity of Rs at a larger scale. However, at a smaller scale, the spatial heterogeneity of Rs was influenced by C, Lw and Lm; (4) the minimum sampling number for soil respiration measurement and its influencing factors reduced greatly with the decrease of confidence level and responding estimation accuracy. The sampling

  20. [Spatial Heterogeneity of Soil Respiration in a Larch Plantation of North China at Different Sampling Scales].

    PubMed

    Yan, Jun-xia; Liang, Ya-nan; Li, Hong-jian; Li, Jun-jian

    2015-12-01

    Based on observations of soil respiration rate (Rs) and both biotic and abiotic factors in Pangquangou Nature Reserve at three sampling scales (4, 2, and 1 m), we studied the spatial heterogeneity of Rs and the factors, and analyzed impacts of soil temperature at the 5, 10 and 15 cm depth (T5, T10, T15), soil moisture over the depth of 0-10 cm (Ws), and soil total nitrogen (N), soil total organic carbon (C), ratio of carbon and nitrogen (C/N), soil total sulfur (S), litter fall mass (Lw) and litter fall moisture (Lm) on the spatial heterogeneity of Rs, respectively. We also calculated the minimum sampling number of all the factors at different confidence levels and under the responding estimation accuracy. The results showed that: (1) the spatial heterogeneity of C/N at 4 m sampling scale, Ws at 2 m sampling scale and T10, T15 at 1 m sampling scale had low variability, while the spatial variation of Rs and other related factors had medium variability. Coefficients of variation of Rs, C/N and S decreased with the increase of the sampling scales, but those of N, C, Ws, T₅, T₁₀, T₁₅, Lw and Lm showed contrary trend; (2) the spatial autocorrelation of Rs, Ws, T₅, T₁₀, T₁₅, Lw and Lm decreased with the decrease of sampling scales but the spatial autocorrelation of C, N, C/N increased with the decrease of sampling scales, and the spatial autocorrelation of S decreased with the decrease of the sampling scales at initial stage and then increased; (3) the key factors that influenced the spatial heterogeneity of soil respiration were different at different sampling scales. Soil temperature was the key factor influencing the spatial heterogeneity of Rs at a larger scale. However, at a smaller scale, the spatial heterogeneity of Rs was influenced by C, Lw and Lm; (4) the minimum sampling number for soil respiration measurement and its influencing factors reduced greatly with the decrease of confidence level and responding estimation accuracy. The sampling

  1. Modeling soil respiration and variations of source components using a multi-factor global climate change experiment

    SciTech Connect

    Chen, Xiongwen; Post, Wilfred M; Norby, Richard J; Classen, Aimee T

    2011-01-01

    Soil respiration is an important component of the global carbon cycle and is highly responsive to changes in soil temperature and moisture. Accurate prediction of soil respiration and its changes under future climatic conditions requires a clear understanding of the processes involved. In spite of this, most current empirical soil respiration models incorporate just few of the underlying mechanisms that may influence its response. In this study, a new partial process-based component model built on source components of soil respiration was tested using data collected from a multi-factor climate change experiment that manipulates CO2 concentrations, temperature and precipitation. These results were then compared to results generated using several other established models. The component model we tested performed well across different treatments of global climate change. In contrast, some other models, which worked well predicting ambient environmental conditions, were unable to predict the changes under different climate change treatments. Based on the component model, the relative proportions of heterotrophic respiration (Rh) in the total soil respiration at different treatments varied from 0.33 to 0.85. There is a significant increase in the proportion of Rh under the elevated atmospheric CO2 concentration in comparison ambient conditions. The dry treatment resulted in higher proportion of Rh at elevated CO2 and ambient T than under elevated CO2 and elevated T. Also, the ratios between root growth and root maintenance respiration varied across different treatments. Neither increased temperature nor elevated atmospheric CO2 changed Q10 values significantly, while the average Q10 value at wet sites was significantly higher than it at dry sites. There was a higher possibility of increased soil respiration under drying relative to wetting conditions across all treatments based on monthly data, indicating that soil respiration may also be related to soil moisture at

  2. Autotrophic component of soil respiration is repressed by drought more than the heterotrophic one in dry grasslands

    NASA Astrophysics Data System (ADS)

    Balogh, János; Papp, Marianna; Pintér, Krisztina; Fóti, Szilvia; Posta, Katalin; Eugster, Werner; Nagy, Zoltán

    2016-09-01

    Summer droughts projected to increase in central Europe due to climate changes strongly influence the carbon cycle of ecosystems. Persistent respiration activities during drought periods are responsible for a significant carbon loss, which may turn the ecosystem from a sink into a source of carbon. There are still gaps in our knowledge regarding the characteristic changes taking place in the respiration of the different components of the ecosystem in response to drought events.In the present study, we combined a physical separation of soil respiration components with continuous measurements of soil CO2 efflux and its isotopic (13C) signals at a dry grassland site in Hungary. The physical separation of soil respiration components was performed by means of inox meshes and tubes inserted into the soil. The root-excluded and root- and mycorrhiza-excluded treatments served to measure the isotopic signals of the rhizospheric, mycorrhizal fungi and heterotrophic components, respectively.In the dry grassland investigated in the study the three components of the soil CO2 efflux decreased at different rates under drought conditions. During drought the contribution made by the heterotrophic components was the highest (54 ± 8 %; mean ±SE). Rhizospheric component was the most sensitive to soil drying with its relative contribution to the total soil respiration dropping from 66 ± 7 (non-stressed) to 35 ± 17 % (mean ±SE) under drought conditions. According to our results the heterotrophic component of soil respiration is the major contributor to the respiration activities during drought events in the dry grassland ecosystem studied.

  3. Soil microbial respiration and PICT responses to an industrial and historic lead pollution: a field study.

    PubMed

    Bérard, Annette; Capowiez, Line; Mombo, Stéphane; Schreck, Eva; Dumat, Camille; Deola, Frédéric; Capowiez, Yvan

    2016-03-01

    We performed a field investigation to study the long-term impacts of Pb soil contamination on soil microbial communities and their catabolic structure in the context of an industrial site consisting of a plot of land surrounding a secondary lead smelter. Microbial biomass, catabolic profiles, and ecotoxicological responses (PICT) were monitored on soils sampled at selected locations along 110-m transects established on the site. We confirmed the high toxicity of Pb on respirations and microbial and fungal biomasses by measuring positive correlations with distance from the wall factory and negative correlation with total Pb concentrations. Pb contamination also induced changes in microbial and fungal catabolic structure (from carbohydrates to amino acids through carboxylic malic acid). Moreover, PICT measurement allowed to establish causal linkages between lead and its effect on biological communities taking into account the contamination history of the ecosystem at community level. The positive correlation between qCO2 (based on respiration and substrate use) and PICT suggested that the Pb stress-induced acquisition of tolerance came at a greater energy cost for microbial communities in order to cope with the toxicity of the metal. In this industrial context of long-term polymetallic contamination dominated by Pb in a field experiment, we confirmed impacts of this metal on soil functioning through microbial communities, as previously observed for earthworm communities.

  4. Soil microbial respiration and PICT responses to an industrial and historic lead pollution: a field study.

    PubMed

    Bérard, Annette; Capowiez, Line; Mombo, Stéphane; Schreck, Eva; Dumat, Camille; Deola, Frédéric; Capowiez, Yvan

    2016-03-01

    We performed a field investigation to study the long-term impacts of Pb soil contamination on soil microbial communities and their catabolic structure in the context of an industrial site consisting of a plot of land surrounding a secondary lead smelter. Microbial biomass, catabolic profiles, and ecotoxicological responses (PICT) were monitored on soils sampled at selected locations along 110-m transects established on the site. We confirmed the high toxicity of Pb on respirations and microbial and fungal biomasses by measuring positive correlations with distance from the wall factory and negative correlation with total Pb concentrations. Pb contamination also induced changes in microbial and fungal catabolic structure (from carbohydrates to amino acids through carboxylic malic acid). Moreover, PICT measurement allowed to establish causal linkages between lead and its effect on biological communities taking into account the contamination history of the ecosystem at community level. The positive correlation between qCO2 (based on respiration and substrate use) and PICT suggested that the Pb stress-induced acquisition of tolerance came at a greater energy cost for microbial communities in order to cope with the toxicity of the metal. In this industrial context of long-term polymetallic contamination dominated by Pb in a field experiment, we confirmed impacts of this metal on soil functioning through microbial communities, as previously observed for earthworm communities. PMID:26233741

  5. The immediate and prolonged effects of climate extremes on soil respiration in a mesic grassland

    NASA Astrophysics Data System (ADS)

    Hoover, David L.; Knapp, Alan K.; Smith, Melinda D.

    2016-04-01

    The predicted increase in the frequency and intensity of climate extremes is expected to impact terrestrial carbon fluxes to the atmosphere, potentially changing ecosystems from carbon sinks to sources, with positive feedbacks to climate change. As the second largest terrestrial carbon flux, soil CO2 efflux or soil respiration (Rs) is strongly influenced by soil temperature and moisture. Thus, climate extremes such as heat waves and extreme drought should have substantial impacts on Rs. We investigated the effects of such climate extremes on growing season Rs in a mesic grassland by experimentally imposing 2 years of extreme drought combined with midsummer heat waves. After this 2 year period, we continued to measure Rs during a recovery year. Two consecutive drought years reduced Rs by about 25% each growing season; however, when normal rainfall returned during the recovery year, formerly droughted plots had higher rates of Rs than control plots (up to +17%). The heat wave treatments had no effect on Rs, alone or when combined with drought, and during the growing season, soil moisture was the primary driver of Rs with little evidence for Rs temperature sensitivity. When compared to aboveground net primary production, growing season Rs was much less sensitive to drought but was more responsive postdrought. These results are consistent with the hypothesis that ecosystems become sources of CO2 during drought because carbon inputs (production) are decreased relatively more than outputs (respiration). Moreover, stimulation of Rs postdrought may lengthen the time required for net carbon exchange to return to predrought levels.

  6. What determines the spatial variability of soil respiration and its temperature dependence (Q10) at catchment scale (Rur Catchment, Germany)?

    NASA Astrophysics Data System (ADS)

    Meyer, Nele; Welp, Gerhard; Amelung, Wulf

    2016-04-01

    Climate change is suspected to alter temperature, soil moisture, and nutrient inputs to the soil. These factors are supposed to strongly influence soil respiration. The degree by which respiration will respond to these changes is crucial for assessing future CO2 feedbacks to the atmosphere. We assume that the temperature sensitivity of soil respiration (Q10) differs spatially depending on land use, soil unit, and texture owing to their diverse properties of soil organic matter quantity and quality. We further hypothesize that the Q10 value is additionally regulated by soil moisture and nutrient status. On the basis of soil and land use maps we divided the Rur catchment (Western Germany, 2350 km²) into so called environmental soil classes (ESC) that combine each a unique combination of the factors land use, soil unit, and texture. We took nine samples from each of the 12 most common ESC's and incubated them at five temperatures (5-25°C), at four soil moisture levels (30-75% water holding capacity), and with an unfertilized and a fertilized treatment. So far, our results indicate that both soil respiration and the Q10 value are spatially highly variable with Q10 values ranging from 1 to 4. The Q10 value is altered by the level of soil moisture and decreases when soils are as moist as 75% water holding capacity. Fertilization has no effect on the Q10 value. Currently, we are processing the whole data-set to derive the effect of ESC's on the Q10 value. Recent data suggest that forest soils are more sensitive to warming than cropland soils.

  7. Spatio-temporal variability of soil respiration in a spruce-dominated headwater catchment in western Germany

    NASA Astrophysics Data System (ADS)

    Bossa, A. Y.; Diekkrüger, B.

    2014-08-01

    CO2 production and transport from forest floors is an important component of the carbon cycle and is closely related to the global atmosphere CO2 concentration. If we are to understand the feedback between soil processes and atmospheric CO2, we need to know more about the spatio-temporal variability of this soil respiration under different environmental conditions. In this study, long-term measurements were conducted in a spruce-dominated forest ecosystem in western Germany. Multivariate analysis-based similarities between different measurement sites led to the detection of site clusters along two CO2 emission axes: (1) mainly controlled by soil temperature and moisture condition, and (2) mainly controlled by root biomass and the forest floor litter. The combined effects of soil temperature and soil moisture were used as a time-dependent rating factor affecting the optimal CO2 production and transport at cluster level. High/moderate/weak time-dependent rating factors were associated with the different clusters. The process-based, most distant clusters were identified using specified pattern characteristics: the reaction rates in the soil layers, the activation energy for bio-chemical reactions, the soil moisture dependency parameter, the root biomass factor, the litter layer factor and the organic matter factor. A HYDRUS-1D model system was inversely used to compute soil hydraulic parameters from soil moisture measurements. Heat transport parameters were calibrated based on observed soil temperatures. The results were used to adjust CO2 productions by soil microorganisms and plant roots under optimal conditions for each cluster. Although the uncertainty associated with the HYDRUS-1D simulations is higher, the results were consistent with both the multivariate clustering and the time-dependent rating of site production. Finally, four clusters with significantly different environmental conditions (i.e. permanent high soil moisture condition, accumulated litter amount

  8. Integrating est.of ecosystem respiration from eddy covariance towers with automated measures of soil respiration: Exam. the dvlpt. and influence of hysteresis in soil respiratory fluxes along a woody plant gradient 2026

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The physiognomic shift in ecosystem structure from a grassland to a woodland may alter the sensitivity of CO2 exchange to variations in growing-season temperatures and precipitation inputs. One large component of ecosystem flux is the efflux of CO2 from the soil (soil respiration, Rsoil), which is ...

  9. The Source of Carbon for Root Respiration

    NASA Astrophysics Data System (ADS)

    Cisneros-Dozal, L.; Trumbore, S.; Zheng, S.

    2004-12-01

    In the Enriched Background Isotope Study (EBIS) that took advantage of a whole-ecosystem radiocarbon label that occurred in the temperate forest near Oak Ridge, Tennessee, we measured the radiocarbon signature of total soil respiration, heterotrophic respiration and root respiration, at different times during the last 3 growing seasons (2002-2004). By applying a mass balance approach, the relative and absolute contributions of heterotrophic and root respiration to total soil respiration were estimated. In contrast to heterotrophic respiration, root respiration seemed to be less affected by changes in soil moisture and temperature but rather showed a link to photosynthetic activity with a very similar pattern during the growing season as that of leaf area index. The radiocarbon signature of root respiration was very dynamic with low values in spring compared to the summer. The sources of variation can include changes in the local atmospheric signature and/or changes in the source of C being respired. Two different sites with different values and patterns of local atmospheric radiocarbon signature showed the same pattern in radiocarbon signatures of root respiration indicating that the source of variation was phenological. Low values during the spring could indicate the use of stored carbohydrates switching to more recent photosynthetic products as the summer progresses. As a first attempt to elucidate the source of C respired by roots, we will compare the radiocarbon content of starch, cellulose and soluble sugars in roots to that of bulk root material and root respired CO2. These radiocarbon signatures can help us identify the pool of C that is most likely being respired by roots during the growing season. A better understanding of the source of C for root respiration has implications for understanding the role of root respiration in C cycling in temperate forests, specifically the timescale over which carbon is fixed through photosynthesis and returned to the

  10. Allometric constraints on, and trade-offs in, belowground carbon allocation and their control of soil respiration across global forest ecosystems.

    PubMed

    Chen, Guangshui; Yang, Yusheng; Robinson, David

    2014-05-01

    To fully understand how soil respiration is partitioned among its component fluxes and responds to climate, it is essential to relate it to belowground carbon allocation, the ultimate carbon source for soil respiration. This remains one of the largest gaps in knowledge of terrestrial carbon cycling. Here, we synthesize data on gross and net primary production and their components, and soil respiration and its components, from a global forest database, to determine mechanisms governing belowground carbon allocation and their relationship with soil respiration partitioning and soil respiration responses to climatic factors across global forest ecosystems. Our results revealed that there are three independent mechanisms controlling belowground carbon allocation and which influence soil respiration and its partitioning: an allometric constraint; a fine-root production vs. root respiration trade-off; and an above- vs. belowground trade-off in plant carbon. Global patterns in soil respiration and its partitioning are constrained primarily by the allometric allocation, which explains some of the previously ambiguous results reported in the literature. Responses of soil respiration and its components to mean annual temperature, precipitation, and nitrogen deposition can be mediated by changes in belowground carbon allocation. Soil respiration responds to mean annual temperature overwhelmingly through an increasing belowground carbon input as a result of extending total day length of growing season, but not by temperature-driven acceleration of soil carbon decomposition, which argues against the possibility of a strong positive feedback between global warming and soil carbon loss. Different nitrogen loads can trigger distinct belowground carbon allocation mechanisms, which are responsible for different responses of soil respiration to nitrogen addition that have been observed. These results provide new insights into belowground carbon allocation, partitioning of soil

  11. Biomarkers as Indicators of Respiration During Laboratory Incubations of Alaskan Arctic Tundra Permafrost Soils

    NASA Astrophysics Data System (ADS)

    Hutchings, J.; Schuur, E.; Bianchi, T. S.; Bracho, R. G.

    2015-12-01

    High latitude permafrost soils are estimated to store 1,330 - 1,580 Pg C, which account for ca. 40% of global soil C and nearly twice that of atmospheric C. Disproportionate heating of high latitude regions during climate warming potentially results in permafrost thaw and degradation of surficial and previously-frozen soil C. Understanding how newly-thawed soils respond to microbial degradation is essential to predicting C emissions from this region. Laboratory incubations have been a key tool in understanding potential respiration rates from high latitude soils. A recent study found that among the common soil measurements, C:N was the best predictor of C losses. Here, we analyzed Alaskan Arctic tundra soils from before and after a nearly 3-year laboratory incubation. Bulk geochemical values as well as the following biomarkers were measured: lignin, amino acids, n-alkanes, and glycerol dialkyl glycerol tetraethers (GDGT). We found that initial C:N did not predict C losses and no significant change in C:N between initial and final samples. The lignin acid to aldehyde (Ad:Al) degradation index showed the same results with a lack of C loss prediction and no significant change during the experiment. However, we did find that C:N and Ad:Al had a significant negative correlation suggesting behavior consistent with expectations. The failure to predict C losses was likely influenced by a number of factors, including the possibility that biomarkers were tracking a smaller fraction of slower cycling components of soil C. To better interpret these results, we also used a hydroxyproline-based amino acid degradation index and n-alkanes to estimate the contribution Sphagnum mosses to soil samples - known to have slower turnover times than vascular plants. Finally, we applied a GDGT soil temperature proxy to estimate the growing season soil temperatures before each incubation, as well as investigating the effects of incubation temperature on the index's temperature estimate.

  12. Exploratory Research - Using Volatile Organic Compounds to Separate Heterotrophic and Autotrophic Forest Soil Respiration

    SciTech Connect

    Roberts, Scott D

    2015-02-09

    The initial focus of this project was to develop a method to partition soil respiration into its components (autotrophic, heterotrophic etc.) using the fingerprint of volatile organic compounds (VOCs) from soils. We were able to identify 63 different VOCs in our study; however, due to technical difficulties we were unable to take reliable measurements in order to test our hypotheses and develop this method. In the end, we changed the objectives of the project. Our new objectives were to characterize the effects of species and soil moisture regime on the composition of soil organic matter. We utilized the soils from the greenhouse experiment we had established for the soil VOC study and determined the lignin biomarker profiles of each of the treatments. We found that moisture had a significant effect on the carbon content of the soils with the low moisture treatments having higher carbon content than the high moisture treatments. We found that the relative yield of syringyl phenols (SP), ligin (Lig), and substituted fatty acids (SFA) were elevated in deciduous planted pots and reduced in conifer planted pots relative to plant-free treatments. Our results suggest nuttall oak preserved lignin and SFA, while loblolly pine lost lignin and SFA similarly to the plant free treatments. Since we did not find that the carbon concentrations of the soils were different between the species, nuttall oak probably replaced more native soil carbon than loblolly pine. This suggests that relative to loblolly pine, nuttall oak is a priming species. Since priming may impact soil carbon pools more than temperature or moisture, determining which species are priming species may facilitate an understanding of the interaction that land use and climate change may have on soil carbon pools.

  13. The pulsed response of soil respiration to precipitation in an African savanna ecosystem: a coupled measurement and modeling approach

    NASA Astrophysics Data System (ADS)

    Fan, Z.; Neff, J. C.; Hanan, N. P.

    2014-12-01

    Savannas cover 60% of the African continent and play an essential role in the global carbon (C) cycle. To better characterize the physical controls over soil respiration in these settings, half-hourly observations of volumetric soil-water content, temperature, and the concentration of carbon dioxide (CO2) at different soil depths were continually measured from 2005 to 2007 under trees ("sub-canopy") and between trees ("inter-canopy") in a savanna vegetation near Skukuza, Kruger National Park, South Africa. The measured soil climate and CO2 concentration data were assimilated into a process-based model that estimates the CO2 production and flux with coupled dynamics of dissolved organic C (DOC) and microbial biomass C. Our results show that temporal and spatial variations in CO2 flux were strongly influenced by precipitation and vegetation cover, with two times greater CO2 flux in the sub-canopy plots (~2421 g CO2 m-2 yr-1) than in the inter-canopy plots (~1290 g CO2 m-2 yr-1). Precipitation influenced soil respiration by changing soil temperature and moisture; however, our modeling analysis suggests that the pulsed response of soil respiration to precipitation [known as "Birch effect (BE)"] is a key control on soil fluxes at this site. At this site, BE contributed to approximately 50% and 65% of heterotrophic respiration or 20% and 39% of soil respiration in the sub-canopy and inter-canopy plots, respectively. These results suggest that pulsed response of respiration to precipitation is an important component of the C cycle of savannas and should be considered in both measurement and modeling studies of carbon exchange in similar ecosystems.

  14. Soil Organic Carbon Sources of Respired CO2 in a Mid-successional North Temperate Forest

    NASA Astrophysics Data System (ADS)

    Medina, N. L.; Hatton, P. J.; Le Moine, J.; Nadelhoffer, K. J.

    2015-12-01

    Given that soil organic matter (SOM) is the largest global terrestrial carbon (C) pool, some fractions of which have turnover times of centuries to millennia, it is critical to understand the mechanisms by which higher net primary productivity (NPP) and higher litter inputs, in the future, as predicted by some models, might alter the potentials of forest soils to serve as long-term C sinks. Here, we use a 10-year-old site in the DIRT (Detritus Input and Removal Treatments) network of litter manipulations to compare plots in a forested, northern-temperate sandy soil that were subjected to double-leaf-litter additions (DL) and both root- and leaf-litter removals (no inputs, NI) to non-manipulated controls. Previous data show that rather than increasing soil organic carbon (SOC) stocks, plots receiving doubled litter inputs lose SOC at rates similar to losses in Control soils. To trace the source of extra mineralized SOC, we analyzed field CO2 effluxes for δ13C and characterized SOC of varying degrees of organo-mineral association with sequential density fractionations. Soils in DL plots respired significantly faster (p=0.095) and proportionally more (p=0.015) than control soils over the course of July, August, and October 2014. This suggests a greater fresh litter contribution to soil efflux in DL than in Control plots after 10 years of treatment. Preliminary data show that intermediate (1.85 - 2.4 g/mL) and dense (>2.4 g/mL) fractions are relatively larger in DL than in Control soils. This suggests that the addition C from doubled litter could be more rapidly transferred into those more dense fractions, or that higher litter inputs prime the decomposition of lighter particulate SOC forms, leading to a relative increase of the dense organo-mineral associations. Using δ13C values to parameterize a multi-source mixing model, we partition the fate of both fresh litter and partially-decomposed SOC and will present on the modeled relative contributions of various

  15. Irrigation Practice Affects Soil Phosphorus Chemistry

    NASA Astrophysics Data System (ADS)

    Ippolito, J.; Bjorneberg, D.

    2011-12-01

    It is expected, given the same water source applied to the same soil, that changes in soil chemistry would be subtle when comparing furrow and sprinkler irrigation practices. From four paired fields, we collected soil (after similar crops were harvested in September) from the 0-5 cm depth. Samples were analyzed for changes in soil P chemistry due to sprinkler or furrow irrigation using: 1) the Olsen soil test P extraction; 2) the alkaline phosphatase enzyme assay; 3) a sequential extraction technique which fractionated inorganic and organic soil P pools; and 4) a measure of the amorphous soil Al and Fe mineral phases. Olsen-extractable soil P was lower under sprinkler irrigation; however, this was not due to a reduction in microbial phosphatase activity. Soils under sprinkler irrigation contained lower inorganic P concentrations in soluble/Al-bound/Fe-bound and in the occluded phases, lesser amounts of organic P present in the moderately labile and non-labile fractions, and contained lower amorphous Fe concentrations. These results indicate that the method of water application affects soil chemistry and nutrient cycling.

  16. Spatio-temporal variability of soil respiration in a spruce-dominated headwater catchment in western Germany

    NASA Astrophysics Data System (ADS)

    Bossa, A. Y.; Diekkrüger, B.

    2014-01-01

    CO2 production and transport from forest floors is an important component of the carbon cycle and is closely related to the global atmosphere CO2 concentration. If we are to understand the feedback between soil processes and atmospheric CO2, we need to know more about the spatio-temporal variability of this soil respiration under different environmental conditions. In this study, long-term measurements were conducted in a spruce-dominated forest ecosystem in western Germany. Multivariate analysis-based similarities between different measurements sites led to the detection of site clusters along two CO2 emission axes: (1) mainly controlled by soil temperature and moisture condition, and (2) mainly controlled by root biomass and the forest floor litter. The combined effects of soil temperature and soil moisture were used as a time-dependent rating factor affecting the optimal CO2 production and transport at cluster level. High/moderate/weak time-dependent rating factors were associated with the different clusters. The process-based most distant clusters were identified using specified pattern characteristics: the reaction rates in the soil layers, the activation energy for bio-chemical reactions, the water sorption and desorption constant, the root biomass factor, the litter layer factor and the organic matter factor. A HYDRUS-1D model system was inversely used to compute soil hydraulic parameters from soil moisture measurements. Heat transport parameters were adjusted based on observed soil temperatures. The results were used to adjust CO2 production and transport characteristics such as the molecular diffusion coefficient of carbon dioxide in air and water and the CO2 production by soil microorganisms and plant roots under optimal conditions for each cluster. Although the uncertainty associated with the HYDRUS-1-D simulations is higher, the results were consistent with both the multivariate clustering and the time-dependent rating of site production

  17. SEASONAL CHANGES IN ROOT AND SOIL RESPIRATION OF OZONE-EXPOSED PONDEROSA PINE (PINUS PONDEROSA) GROWN IN DIFFERENT SUBSTRATES

    EPA Science Inventory

    Exposure to(ozone 0-3)has been shown to decrease the allocation of carbon to tree roots. Decreased allocation of carbon to roots might disrupt root metabolism and rhizosphere organisms. The effects of soil type and shoot 0, exposure on below-ground respiration and soil microbial ...

  18. Rearing Tenebrio molitor in BLSS: Dietary fiber affects larval growth, development, and respiration characteristics

    NASA Astrophysics Data System (ADS)

    Li, Leyuan; Stasiak, Michael; Li, Liang; Xie, Beizhen; Fu, Yuming; Gidzinski, Danuta; Dixon, Mike; Liu, Hong

    2016-01-01

    Rearing of yellow mealworm (Tenebrio molitor L.) will provide good animal nutrition for astronauts in a bioregenerative life support system. In this study, growth and biomass conversion data of T. molitor larvae were tested for calculating the stoichiometric equation of its growth. Result of a respiratory quotient test proved the validity of the equation. Fiber had the most reduction in mass during T. molitor‧s consumption, and thus it is speculated that fiber is an important factor affecting larval growth of T. molitor. In order to further confirm this hypothesis and find out a proper feed fiber content, T. molitor larvae were fed on diets with 4 levels of fiber. Larval growth, development and respiration in each group were compared and analyzed. Results showed that crude-fiber content of 5% had a significant promoting effect on larvae in early instars, and is beneficial for pupa eclosion. When fed on feed of 5-10% crude-fiber, larvae in later instars reached optimal levels in growth, development and respiration. Therefore, we suggest that crude fiber content in feed can be controlled within 5-10%, and with the consideration of food palatability, a crude fiber of 5% is advisable.

  19. Understanding environmental drivers in the regulation of soil respiration dynamics after fire in semi-arid ecosystems

    NASA Astrophysics Data System (ADS)

    Muñoz-Rojas, Miriam; Lewandrowski, Wolfgang; Erickson, Todd E.; Dixon, Kingsley W.; Merritt, David J.

    2016-04-01

    Keywords: Pilbara, soil CO2 efflux, soil C, soil moisture, soil temperature Introduction Soil respiration (Rs) has become a major research focus given the increase in atmospheric CO2 emissions and the large contribution of these CO2 fluxes from soils (Van Groenigen et al., 2014). In addition to its importance in the global C cycle, Rs is a fundamental indicator of soil health and quality that reflects the level of microbial activity and provides an indication of the ability of soils to support plant growth (Oyonarte et al., 2012; Munoz-Rojas et al., 2015). Wildfires can have a significant impact on Rs rates, with the scale of the impact depending on environmental factors such as temperature and moisture, and organic C content in the soil. Vegetation cover can have a significant effect on regulating organic C contents; and while advances are made into understanding the effects of fire on organic C contents and CO2 fluxes (Granged et al., 2011; Willaarts et al., 2015; Muñoz-Rojas et al., 2016), there is limited knowledge of the variability of Rs across ecosystem types, vegetation communities, and responses to fire. In this research we aimed to assess the impacts of a wildfire on the soil CO2 fluxes and soil respiration in a semi-arid ecosystem of Western Australia (Pilbara biogeographical region), and to understand the main environmental drivers controlling these fluxes in different vegetation types. The study has application for other arid and semi-arid regions of the world. Methods The study area was selected following a wildfire that affected 25 ha in February 2014. Twelve plots were established in the burnt site (B) within a 400 m2 area, and 12 plots in an adjacent unburnt control site. At each site, three plots were installed below the canopy of each of the most representative vegetation types of the areas: Eucalyptus trees, Acacia shrubs and Triodia grasses, and three on bare soil. Soil sampling and measurement of soil CO2 efflux, temperature and moisture were

  20. Modeling Soil Organic Carbon Turnover in Four Temperate Forests Based on Radiocarbon Measurements of Heterotrophic Respiration and Soil Organic Carbon

    NASA Astrophysics Data System (ADS)

    Ahrens, B.; Borken, W.; Muhr, J.; Schrumpf, M.; Savage, K. E.; Wutzler, T.; Trumbore, S.; Reichstein, M.

    2011-12-01

    Soils of temperate forests store significant amounts of soil organic matter and are considered to be net sinks of atmospheric CO2. Soil organic carbon (SOC) dynamics have been studied using the Δ14C signature of bulk SOC or different SOC fractions as observational constraints in SOC models. Further, the Δ14C signature of CO2 evolved during the incubation of soil and roots has been widely used together with Δ14C of total soil respiration to partition soil respiration into heterotrophic respiration (Rh) and root respiration. However, these data have rarely been used together as observational constraints to determine SOC turnover times. Here, we present a multiple constraints approach, where we used SOC stock and its Δ14C signature, and heterotrophic respiration and its Δ14C signature to estimate SOC turnover times of a simple serial two-pool model via Bayesian optimization. We used data from four temperate forest ecosystems in Germany and the USA with different disturbance and management histories from selective logging to afforestation in the late 19th and early 20th century. The Δ14C signature of the atmosphere with its prominent bomb peak was used as a proxy for the Δ14C signature of aboveground and belowground litterfall. The Δ14C signature of litterfall was lagged behind the atmospheric signal to account for the period between photosynthetic fixation of carbon and its addition to SOC pools. We showed that the combined use of Δ14C measurements of Rh and SOC stocks helped to better constrain turnover times of the fast pool (primarily by Δ14C of Rh) and the slow pool (primarily by Δ14C of SOC). In particular, by introducing two additional parameters that describe the deviation from steady state of the fast and slow cycling pool for both SOC and SO14C, we were able to demonstrate that we cannot maintain the often used steady-state assumption of SOC models in general. Furthermore, a new transport version of our model, including SOC transport via

  1. Soil microbial community composition does not predominantly determine the variance of heterotrophic soil respiration across four subtropical forests.

    PubMed

    Wei, Hui; Xiao, Guoliang; Guenet, Bertrand; Janssens, Ivan A; Shen, Weijun

    2015-01-19

    To explore the importance of soil microbial community composition on explaining the difference in heterotrophic soil respiration (R(h)) across forests, a field investigation was conducted on Rh and soil physiochemical and microbial properties in four subtropical forests in southern China. We observed that Rh differed significantly among forests, being 2.48 ± 0.23, 2.31 ± 0.21, 1.83 ± 0.08 and 1.56 ± 0.15 μmol m(-2) s(-1) in the climax evergreen broadleaf forest (BF), the mixed conifer