Journal articles: 'Respiration variations'

1

Liu, Yanchun, Qing Shang, Lei Wang, and Shirong Liu. "Effects of Understory Shrub Biomass on Variation of Soil Respiration in a Temperate-Subtropical Transitional Oak Forest." Forests 10, no. 2 (January 23, 2019): 88. http://dx.doi.org/10.3390/f10020088.

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Quantification of the temporal and spatial variations of soil respiration is an essential step in modeling soil carbon (C) emission associated with the spatial distribution of plants. To examine the temporal and spatial variations of soil respiration and its driving factors, we investigated soil respiration, microclimate, and understory vegetation in a 50 m × 70 m plot in a climatic transitional zone oak forest in Central China. The temporal variation of soil respiration based on the 21 measurements ranged from 15.01% to 30.21% across the 48 subplots. Structural equation modeling showed that soil temperature and understory shrub biomass had greater positive effects on the seasonal variability of soil respiration. The spatial variation of soil respiration of the 48 subplots varied from 3.61% to 6.99% during the 21 measurement campaigns. Understory shrub biomass and belowground fine root biomass positively regulated the spatial variation of soil respiration. Soil respiration displayed strong spatial autocorrelation, with an average spatial correlation length of 20.1 m. The findings highlight the importance of understory shrub and belowground biomass in regulating the temporal and spatial heterogeneity of soil respiration in forest ecosystems, and the need to carefully address it to robustly estimate the contribution of soil C emission in terrestrial C cycling.

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Wang, Dandan, Xinxiao Yu, Guodong Jia, Wei Qin, and Zhijie Shan. "Variations in Soil Respiration at Different Soil Depths and Its Influencing Factors in Forest Ecosystems in the Mountainous Area of North China." Forests 10, no. 12 (November 27, 2019): 1081. http://dx.doi.org/10.3390/f10121081.

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An in-depth understanding of the dominant factors controlling soil respiration is important to accurately estimate carbon cycling in forest ecosystems. However, information on variations in soil respiration at different soil depths and the influencing factors in forest is limited. This study examined the variations in soil respiration at two soil depths (0–10 and 10–20 cm) as well as the effects of soil temperature, soil water content, litter removal, and root cutting on soil respiration in three typical forest types (i.e., Pinus tabulaeformis Carrière, Platycladus orientalis (L.) Franco, and Quercus variabilis Bl.) in the mountainous area of north China from March 2013 to October 2014. The obtained results show that soil respiration exhibited strong seasonal variation and decreased with soil depth. Soil respiration was exponentially correlated to soil temperature, and soil respiration increased with soil water content until reaching threshold values (19.97% for P. tabulaeformis, 16.65% for P. orientalis, and 16.90% for Q. variabilis), followed by a decrease. Furthermore, interactions of soil temperature and water content significantly affected soil respiration at different soil depths of forest types, accounting for 68.9% to 82.6% of the seasonal variation in soil respiration. In addition to soil temperature and water content, aboveground litter and plant roots affected soil respiration differently. In the three forest types, soil respiration at two soil depths decreased by 22.97% to 29.76% after litter removal, and by 44.84% to 53.76% after root cutting. The differences in soil respiration reduction between the two soil depths are largely attributed to variations in substrate availability (e.g., soil organic content) and soil carbon input (e.g., litter and fine root biomass). The obtained findings indicate that soil respiration varies at different soil depths, and suggest that in addition to soil temperature and water content, soil carbon input and dissolved organic substances may exert a strong effect on forest soil respiration.

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Cheng, Xiang Rong, Mu Kui Yu, Tong Gui Wu, and Zong Xing Wang. "Soil Respiration and its Controlling Factors in Six Coastal Young Monoculture Plantations." Advanced Materials Research 726-731 (August 2013): 3751–56. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.3751.

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Biotic and abiotic factors how to influence soil respiration in different young monoculture plantations are not clearly understood. Soil respiration and its controlling factors were studied in six monoculture plantations in the coastal area of Shanghai, China. Soil respiration was significant difference among six stands. Variations of soil respiration in six plots were not directly related to changes in soil water content, but significant relationship was observed between soil respiration and soil temperature. The variation of soil respiration was firmly correlated to the variation of leaf area index (LAI) or gap fraction (GF), soil respiration enhanced with the increase of GF (or decreasing LAI). The microclimate within forest and soil temperature also had positively correlation with soil respiration, but which mainly were affected by GF or LAI. There was no significant relationship between soil respiration and either root biomass or soil nutrients.

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Adachi, Minaco, Atsushi Ishida, Sarayudh Bunyavejchewin, Toshinori Okuda, and Hiroshi Koizumi. "Spatial and temporal variation in soil respiration in a seasonally dry tropical forest, Thailand." Journal of Tropical Ecology 25, no. 5 (September 2009): 531–39. http://dx.doi.org/10.1017/s026646740999006x.

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Abstract:Spatial and seasonal variation in soil respiration rates were investigated in a tropical dry forest in Thailand. The spatial variation was examined at 50 points within a 2-ha plot in the forest floor during the dry and wet seasons. The seasonal and diurnal variations in soil respiration were measured at 16 and 5 points, respectively. The mean soil respiration rate during the wet season was 1041 ± 542 mg CO2 m−2 h−1 (mean ± SD), which is about twice that during the dry season. Soil respiration rate was negatively correlated with soil water content during the wet season. A polynomial equation using seasonal data describes soil respiration and water content: soil respiration rate increased with soil water content, but started to drop when soil water content exceeded 21%. The diurnal variation in soil respiration rate during the wet season was positively correlated with soil temperature, whereas during the wet season it was not correlated with soil temperature. The diurnal variation in soil respiration rate during the dry season showed a midday depression. The estimation of soil carbon flux with polynomial equations should incorporate different functions for the wet and dry seasons in tropical dry forests.

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Talasila, P. Chowdary, Arthur C. Cameron, and Dennis W. Joles. "236 RESPIRATION AND TEMPERATURE VARIATION EFFECTS ON MA PACKAGING OF STRAWBERRIES AND RASPBERRIES." HortScience 29, no. 5 (May 1994): 463c—463. http://dx.doi.org/10.21273/hortsci.29.5.463c.

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Natural variation of product respiration rate and temperature variation during shipping and marketing influence the atmosphere inside MA packages. Respiration rate variation data was collected at 0C and 5.5C for `Allstar' and `Honeoye' strawberries and at 5.5C for `Heritage' raspberries. Coefficient of variation was 8% for raspberries and ranged from 6.5% to 12.5% for strawberries. To determine package-to-package variations, steady-state O2 partial pressures were measured in 100 similarly designed packages and frequency distributions were constructed. For `Honeoye' variety, `O2 partial pressures ranged from 3.5 kPa to 13.7 kPa with a median of 7.5 kPa in one set of packages and from 0.4 to 1.65 kPa with a median of 0.6 kPa in another set of packages with different design. Large variations were also observed for `Allstar' variety and raspberries. The results compared well with package O2 distributions predicted by a mathematical model that was constructed based on respiration rate variation. A modeling approach was used to predict frequency distributions and changes in gas levels in strawberry and raspberry packages for several possible temperature variation situations and for different types of package designs.

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Liu, Ying, and Shi Jie Han. "Diurnal and Seasonal Variations in Soil Respiration in a Temperate Broad-Leaved Korean Pine Forest, China." Applied Mechanics and Materials 295-298 (February 2013): 2318–23. http://dx.doi.org/10.4028/www.scientific.net/amm.295-298.2318.

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LI-6400-09 soil CO2 flux chamber (LI-COR, NE USA) and Subtraction method were used to investigate the diurnal and seasonal variations of soil respiration and the contribution of root respiration to total soil respiration in a temperate broad-leaved Korean Pine forest ecosystem, China. Soil temperatures at 5 cm depth were recorded by Hobo thermal recorder (at 1 h interval) and year-round soil respiration and the contribution of root could be calculated based the Q10 relationship. The results indicated that: Diurnal variations of total soil respiration (TRs) and root-severed soil respiration (RRs) were highly associated with variations of soil temperature at 5 cm depth in a day. total soil respiration, root-severed soil respiration (RRs) and root respiration (Rs) followed a similar seasonal trend that varied markedly during the growing season with high rates in summer and low rates in spring and autumn, coinciding with summer wet and high temperature, and in spring and autumn, with the lower temperature. The mean rates of TRs, RRs and Rs was 3.68, 2.02 and 1.63 µmol m-2 s-1, which were 1392.63, 764.43 and 616.84 g C m-2 y-1 respectively from May to September in 2004. TRs, RRs and Rs were exponentially correlated with temperature during growing season. However, there were no correlations between soil respiration and soil volumetric moisture. The Q10 values for TRs, RRs and Rs were 2.40, 2.42 and 2.50 respectively. The root was a major component of soil respiration, accounting for from 29.3 to 58.7% of the total soil respiration from May to September in 2004. The year-round mean of TRs, RRs and Rs were 1.95, 1.07 and 0.81 µmol m-2 s-1, which were 737.94, 404.92 and 306.53 g C m-2 y-1 respectively. Root respiration contributed 41.0% to the annual total soil respiration.

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Francioni, Matteo, Paride D’Ottavio, Roberto Lai, Laura Trozzo, Katarina Budimir, Lucia Foresi, Ayaka Wenhong Kishimoto-Mo, et al. "Seasonal Soil Respiration Dynamics and Carbon-Stock Variations in Mountain Permanent Grasslands Compared to Arable Lands." Agriculture 9, no. 8 (July 27, 2019): 165. http://dx.doi.org/10.3390/agriculture9080165.

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Permanent grasslands provide a wide array of ecosystem services. Despite this, few studies have investigated grassland carbon (C) dynamics, and especially those related to the effects of land-use changes. This study aimed to determine whether the land-use change from permanent grassland to arable lands resulted in variations in the soil C stock, and whether such variations were due to increased soil respiration or to management practices. To address this, seasonal variations of soil respiration, sensitivity of soil respiration to soil temperature (Q10), and soil C stock variations generated by land-use changes were analyzed in a temperate mountain area of central Italy. The comparisons were performed for a permanent grassland and two adjacent fields, one cultivated with lentil and the other with emmer, during the 2015 crop year. Soil respiration and its heterotrophic component showed different spatial and temporal dynamics. Annual cumulative soil respiration rates were 6.05, 5.05 and 3.99 t C ha−1 year−1 for grassland, lentil and emmer, respectively. Both soil respiration and heterotrophic soil respiration were positively correlated with soil temperature at 10 cm depth. Derived Q10 values were from 2.23 to 6.05 for soil respiration, and from 1.82 to 4.06 for heterotrophic respiration. Soil C stock at over 0.2 m in depth was 93.56, 48.74 and 46.80 t C ha−1 for grassland, lentil and emmer, respectively. The land-use changes from permanent grassland to arable land lead to depletion in terms of the soil C stock due to water soil erosion. A more general evaluation appears necessary to determine the multiple effects of this land-use change at the landscape scale.

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Liu, Gang, Rei Sonobe, and Quan Wang. "Spatial Variations of Soil Respiration in Arid Ecosystems." Open Journal of Ecology 06, no. 04 (2016): 192–205. http://dx.doi.org/10.4236/oje.2016.64020.

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9

Chi, Yonggang, Qingpeng Yang, Lei Zhou, Ruichang Shen, Shuxia Zheng, Zhaoyang Zhang, Zhenzhen Zhang, et al. "Temperature Sensitivity in Individual Components of Ecosystem Respiration Increases along the Vertical Gradient of Leaf–Stem–Soil in Three Subtropical Forests." Forests 11, no. 2 (January 25, 2020): 140. http://dx.doi.org/10.3390/f11020140.

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Temperature sensitivity (Q10) of ecosystem respiration (ER) is a crucial parameter for predicting the fate of CO2 in terrestrial e cosystems under global warming. Most studies focus their attention in the variation of Q10 in one or two components of ER, but not in the integration or comparison among Q10 in major components of ER. Vertical and seasonal variations in individual components, including leaf respiration, stem respiration and soil respiration, of ER were observed synchronously along the gradient of leaf–stem–soil over a 2 year period in three forest stands dominated by masson pine, loblolly pine and oak, respectively, in a subtropical forest ecosystem of central China. We found that Q10 in individual components of ER increased along the vertical gradient of leaf–stem–soil. The vertical pattern of Q10 in individual components of ER was ascribed to variations of diurnal temperature range (DTR) and activation energy (ΔHa). These results suggest that a vertical pattern of Q10 in individual components of ER along the gradient of leaf–stem–soil should be taken into consideration in process-based models that simulate respiratory carbon flux in terrestrial ecosystems.

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Xu, Ming, Terry A. DeBiase, and Ye Qi. "A simple technique to measure stem respiration using a horizontally oriented soil chamber." Canadian Journal of Forest Research 30, no. 10 (October 1, 2000): 1555–60. http://dx.doi.org/10.1139/x00-083.

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This paper introduces a simple technique, the horizontally oriented soil chamber (HOSC), to measure stem and branch respiration easily and accurately. We extend the function of the LI-6400-09 soil CO2 flux chamber by attaching a custom-built polyvinyl chloride (PVC) collar to the stem surface. For small trees and branches we use pipe bushings to connect the chamber to stem surface. Using this technique we measured stem respiration in a young ponderosa pine (Pinus ponderosa Dougl. ex Laws.) plantation in the Sierra Nevada Mountains near Georgetown, Calif., from June to December 1998. The diurnal and seasonal variations in respiration rate correlate well with the corresponding stem temperature variation. The Q10 values varied from 1.9 to 2.8, which are within the range of Q10 values (1.3-3.3) reported in previous studies. The range of our stem respiration results (3.5-7.2 µmol·m-2·s-1) compares favorably with previous studies on young ponderosa pine trees. This technique provides an alternative to measure stem respiration, which employs widely used, commercially available, portable respiration measurement equipment and requires almost no additional equipment, especially for current owners of LI-6400 systems. Thus, the HOSC technique is appropriate for examining spatial variation of stem respiration.

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Diao, Haoyu, Anzhi Wang, Fenghui Yuan, Dexin Guan, Guanhua Dai, and Jiabing Wu. "Environmental Effects on Carbon Isotope Discrimination from Assimilation to Respiration in a Coniferous and Broad-Leaved Mixed Forest of Northeast China." Forests 11, no. 11 (October 30, 2020): 1156. http://dx.doi.org/10.3390/f11111156.

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Carbon (C) isotope discrimination during photosynthetic CO2 assimilation has been extensively studied, but the whole process of fractionation from leaf to soil has been less well investigated. In the present study, we investigated the δ13C signature along the C transfer pathway from air to soil in a coniferous and broad-leaved mixed forest in northeast China and examined the relationship between δ13C of respiratory fluxes (leaf, trunk, soil, and the entire ecosystem) and environmental factors over a full growing season. This study found that the δ13C signal of CO2 from canopy air was strongly imprinted in the organic and respiratory pools throughout C transfer due to the effects of discrimination and isotopic mixing on C assimilation, allocation, and respiration processes. A significant difference in isotopic patterns was found between conifer and broadleaf species in terms of seasonal variations in leaf organic matter. This study also found that δ13C in trunk respiration, compared with that in leaf and soil respiration, was more sensitive to seasonal variations of environmental factors, especially soil temperature and soil moisture. Variation in the δ13C of ecosystem respiration was correlated with air temperature with no time lag and correlated with soil temperature and vapor pressure deficit with a lag time of 10 days, but this correlation was relatively weak, indicating a delayed linkage between above- and belowground processes. The isotopic linkage might be confounded by variations in atmospheric aerodynamic and soil diffusion conditions. These results will help with understanding species differences in isotopic patterns and promoting the incorporation of more influencing factors related to isotopic variation into process-based ecosystem models.

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Tamai, K. "Effects of environmental factors and soil properties on topographic variations of soil respiration." Biogeosciences Discussions 6, no. 6 (November 24, 2009): 10935–61. http://dx.doi.org/10.5194/bgd-6-10935-2009.

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Abstract. Soil respiration rates were measured along different parts of a slope in (a) an evergreen forest with mature soil and (b) a deciduous forest with immature soil. The effects of soil temperature, soil moisture, and soil properties on soil respiration rates were estimated individually, and the magnitudes of these effects were compared between the deciduous and evergreen forests. In the evergreen forest with mature soil, soil properties had the greatest effect on soil respiration rates, followed by soil moisture and soil temperature. These results may be explained by different properties of soils that matured under different environments. Thus, we argue that the low soil respiration rates in Plot L of the evergreen forest resulted from soil properties and not from wet soil conditions. In the deciduous forest, soil respiration rates were more strongly affected by soil moisture and soil temperature than by soil properties, which were likely due to the immaturity of the forest soil.

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Dhital, Deepa, Suman Prajapati, Sanu Raja Maharjan, and Toshiyuki Ohtsuka. "Ensuring the effects of climate warming; the sensitivity of controlling factors on soil respiration in Sub-Tropical grassland." Tropical Plant Research 7, no. 3 (December 31, 2020): 529–40. http://dx.doi.org/10.22271/tpr.2020.v7.i3.065.

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Prevailing climate change is expected due to carbon dioxide emission to the atmosphere through soil respiration and perhaps the alteration in the terrestrial carbon cycle. The measurements to establish the effect and sensitivity of soil temperature, soil water content and plant biomass on soil respiration was performed in the sub-tropical grassland located in Central Nepal. Field measurements of soil respiration was conducted by using the closed-chamber method, and soil temperature, soil water content and plant biomass were monitored in the years 2015 and 2016. The soil respiration showed positive significant exponential function which accounted for 74.6% (R2=0.746, p<0.05) of its variation with the soil temperature. The temperature sensitivity of soil respiration, Q10 value obtained was 2.68. Similarly, soil respiration showed a positive significant exponential function that accounted for 37.2% (R2=0.372, p<0.05) of its variation with the soil water content. Remarkable seasonal and monthly variations were observed in soil respiration, soil temperature and soil water content, and the plant biomass as well followed the seasonal trend in variation of the soil respiration. Average soil respiration during measurements period was observed 325.51 mg CO2 m-2 h-1 and the annual soil respiration of the grassland in the years 2015 and 2016 was estimated 592.35 g C m-2 y-1. The study confirmed that soil temperature is the most influential primary factor in controlling soil respiration along with the soil water content and plant biomass. This research indicates that through emissions under the increasing temperature and precipitation, in the changing climate, the sub-tropical grassland could be an additional source of carbon dioxide to the atmosphere that might spur risk for further warming.

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Wang, Xu, Kaikai Fan, Yuchun Yan, Baorui Chen, Ruirui Yan, Xiaoping Xin, and Linghao Li. "Controls of Seasonal and Interannual Variations on Soil Respiration in a Meadow Steppe in Eastern Inner Mongolia." Agronomy 13, no. 1 (December 21, 2022): 20. http://dx.doi.org/10.3390/agronomy13010020.

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Understanding long-term seasonal and interannual patterns of soil respiration with their controls is essential for accurately quantifying carbon fluxes at a regional scale. During the period from 2009 to 2014, an automatic measurement system (LI-8150, Licor Ldt., Lincoln, Nebraska, USA) was employed for the measurement of soil respiration in a meadow steppe of eastern Inner Mongolia. We found that the seasonal pattern of soil respiration was controlled mainly by the soil temperature, which explained about 82.19% of the variance. Annual soil respiration varied between 391.4 g cm−2 and 597.7 g cm−2, and significantly correlated with soil moisture, suggesting that soil moisture was the most predominant factor controlling the annual variations of soil respiration in this meadow steppe. A double factorial exponential model including both soil temperature (TS) and soil water content (SWC) (y = 6.084×exp(0.098 TS×SWC) − 5.636) explains 72.2% of the overall variance in soil respiration. We also detected a temporal inconsistency of 2–3 months in the effects of precipitation on soil respiration versus canopy biomass production, which was presumably a main mechanism explaining the weak relationships between soil respiration and phytomass components in this ecosystem. Our findings have important implications for better understanding and accurately assessing the carbon cycling characteristics of terrestrial ecosystems in response to climate change in a temporal perspective.

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Tamai, K. "Effects of environmental factors and soil properties on topographic variations of soil respiration." Biogeosciences 7, no. 3 (March 26, 2010): 1133–42. http://dx.doi.org/10.5194/bg-7-1133-2010.

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Abstract. Soil respiration rates were measured along different parts of a slope in (a) an evergreen forest with common brown forest soil and (b) a deciduous forest with immature soil. The effects of soil temperature, soil moisture and soil properties were estimated individually, and the magnitudes of these effects in the deciduous and evergreen forests were compared. In the evergreen forest with common brown forest soil, soil properties had the greatest effect on soil respiration rates, followed by soil moisture and soil temperature. These results may be explained by the fact that different soil properties matured within different environments. It can be argued that the low soil respiration rates in the low parts of the slope in the evergreen forest resulted from soil properties and not from wet soil conditions. In the deciduous forest, soil respiration rates were more strongly affected by soil moisture and soil temperature than by soil properties. These effects were likely due to the immaturity of the forest soil.

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Ayala-Montejo, Diana, Eduardo Valdés-Velarde, Gerardo Sergio Benedicto-Valdés, Esteban Escamilla-Prado, Rufo Sánchez-Hernández, Juan Fernando Gallardo, and Pablo Martínez-Zurimendi. "Soil Biological Activity, Carbon and Nitrogen Dynamics in Modified Coffee Agroforestry Systems in Mexico." Agronomy 12, no. 8 (July 29, 2022): 1794. http://dx.doi.org/10.3390/agronomy12081794.

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(1) Background: Coffee agroforestry systems (CAFS) in Veracruz, Mexico, are being displaced by avocado monocultures due to their high economic value. This change can generate alterations in the type of organic residues produced and soil biological activity (SBA) which is sensitive to climatic variations, changes in floristic composition, and agronomic management. It can be evaluated through soil respiration and macrofauna, both related to soil carbon (C) and nitrogen (N) dynamics. The objective was to: (1) Analyze the variation of SBA as well as the C and N dynamics in modified coffee agroforestry systems; (2) Methods: Three CAFS (renewed, intensive pruning, and with the introduction of avocados) and an avocado plantation were compared. The evaluations were conducted during the period 2017–2019. Soil parameters (respiration, macrofauna, C and N contents) and C content of plant biomass were measured in plots of 25 × 25 m2 from three soil depths in triplicate. Spearman’s test and a principal component analysis were performed to determine the structural dependence on C and N dynamics; (3) Results: The introduction of avocado showed the lowest soil respiration values (with 193 g CO2 ha−1 h−1 at 0–10 cm depth), this system did not display soil macrofauna and increased soil organic carbon content. The soil C/N ratio was sensitive to the introduction of avocado. Correlation between soil respiration and litter-related parameters was positive, but it was negatively correlated with soil organic matter and total soil nitrogen, explaining 67.7% of the variation; (4) Conclusions: Modification of CAFS generated variations in the SBA and soil C and N contents.

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Wang, Xianwei, Xiaoxin Sun, Li Sun, Ning Chen, and Yu Du. "Small-Scale Variability of Soil Quality in Permafrost Peatland of the Great Hing’an Mountains, Northeast China." Water 14, no. 17 (August 23, 2022): 2597. http://dx.doi.org/10.3390/w14172597.

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Permafrost peatland is a unique ecosystem that represents a huge carbon terrestrial pool. Soil quality has a relatively high level of variation at small scale in this ecosystem and is closely related to the carbon cycle. To quantify this variability, we analyzed total organic carbon, total nitrogen, total phosphorus, nutrient, and element (sodium, magnesium, potassium, and calcium), and microbial respiration activities (microbial biomass carbon, soil basal respiration, metabolic, and microbial quotients) in the humus layer to deeper soil layer of 6 plots at small scale (meters). For all samples, the coefficients of variation (CV) values of total carbon concentrations were lowest and these values of sodium, magnesium, potassium, and calcium concentrations were higher than those of total carbon, nitrogen, and phosphorus concentrations. The largest variations of total phosphorus, ash, and Na were in the 10–20 cm layer with soil depths. The litter decomposition and water table may cause this variation at small-scale. The CV values of microbial respiration activities were largest compared with soil properties. There were different correlations between basal respiration and soil properties among the plots. Our results showed that soil properties and microbial respiration activities in permafrost peatland exhibits considerable variability at small scale. This variability indicates that sampling location and number are very important in peatland studies if we want to accurately estimate the biogeochemistry in a peatland.

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Davidson, K. G., A. D. Bersten, T. E. Nicholas, P. R. Ravenscroft, and I. R. Doyle. "Measurement of tidal volume by using transthoracic impedance variations in rats." Journal of Applied Physiology 86, no. 2 (February 1, 1999): 759–66. http://dx.doi.org/10.1152/jappl.1999.86.2.759.

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The application of impedance pneumography for monitoring respiration in small animals has been limited by problems with calibration. With improved instrumentation, we describe the calibration of tidal volume in anesthetized rats. The detection of changes in voltage, reflecting the electrical impedance variations associated with respiration, was optimized by using disposable adhesive silver-silver chloride electrodes, advanced circuitry, and analog-to-digital recording instrumentation. We found a linear relationship between change in impedance and tidal volume in individual rats ( R2≥ 98%), which was strongly influenced by rat weight. Consequently, a calibration equation incorporating change in impedance and rat weight was derived to predict tidal volume. Comparison of the predicted and true tidal volumes revealed a mean R2≥ 98%, slopes of ∼1, intercepts of ∼0, and bias of ∼0.07 ml. The predicted volumes were not significantly affected by either frequency of respiration or pulmonary edema. We conclude that impedance pneumography provides a valuable tool for the noninvasive measurement of tidal volume in anesthetized rats.

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Konings, Alexandra G., A. Anthony Bloom, Junjie Liu, Nicholas C. Parazoo, David S. Schimel, and Kevin W. Bowman. "Global satellite-driven estimates of heterotrophic respiration." Biogeosciences 16, no. 11 (June 4, 2019): 2269–84. http://dx.doi.org/10.5194/bg-16-2269-2019.

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Abstract. While heterotrophic respiration (Rh) makes up about a quarter of gross global terrestrial carbon fluxes, it remains among the least-observed carbon fluxes, particularly outside the midlatitudes. In situ measurements collected in the Soil Respiration Database (SRDB) number only a few hundred worldwide. Similarly, only a single data-driven wall-to-wall estimate of annual average heterotrophic respiration exists, based on bottom-up upscaling of SRDB measurements using an assumed functional form to account for climate variability. In this study, we exploit recent advances in remote sensing of terrestrial carbon fluxes to estimate global variations in heterotrophic respiration in a top-down fashion at monthly temporal resolution and 4∘×5∘ spatial resolution. We combine net ecosystem productivity estimates from atmospheric inversions of the NASA Carbon Monitoring System-Flux (CMS-Flux) with an optimally scaled gross primary productivity dataset based on satellite-observed solar-induced fluorescence variations to estimate total ecosystem respiration as a residual of the terrestrial carbon balance. The ecosystem respiration is then separated into autotrophic and heterotrophic components based on a spatially varying carbon use efficiency retrieved in a model–data fusion framework (the CARbon DAta MOdel fraMework, CARDAMOM). The resulting dataset is independent of any assumptions about how heterotrophic respiration responds to climate or substrate variations. It estimates an annual average global average heterotrophic respiration flux of 43.6±19.3 Pg C yr−1. Sensitivity and uncertainty analyses showed that the top-down Rh are more sensitive to the choice of input gross primary productivity (GPP) and net ecosystem productivity (NEP) datasets than to the assumption of a static carbon use efficiency (CUE) value, with the possible exception of the wet tropics. These top-down estimates are compared to bottom-up estimates of annual heterotrophic respiration, using new uncertainty estimates that partially account for sampling and model errors. Top-down heterotrophic respiration estimates are higher than those from bottom-up upscaling everywhere except at high latitudes and are 30 % greater overall (43.6 Pg C yr−1 vs. 33.4 Pg C yr−1). The uncertainty ranges of both methods are comparable, except poleward of 45∘ N, where bottom-up uncertainties are greater. The ratio of top-down heterotrophic to total ecosystem respiration varies seasonally by as much as 0.6 depending on season and climate, illustrating the importance of studying the drivers of autotrophic and heterotrophic respiration separately, and thus the importance of data-driven estimates of Rh such as those estimated here.

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Baumert, Mathias, Michal Javorka, and Muammar Kabir. "Joint symbolic dynamics for the assessment of cardiovascular and cardiorespiratory interactions." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2034 (February 13, 2015): 20140097. http://dx.doi.org/10.1098/rsta.2014.0097.

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Beat-to-beat variations in heart period provide information on cardiovascular control and are closely linked to variations in arterial pressure and respiration. Joint symbolic analysis of heart period, systolic arterial pressure and respiration allows for a simple description of their shared short-term dynamics that are governed by cardiac baroreflex control and cardiorespiratory coupling. In this review, we discuss methodology and research applications. Studies suggest that analysis of joint symbolic dynamics provides a powerful tool for identifying physiological and pathophysiological changes in cardiovascular and cardiorespiratory control.

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D.Yu., Makhkamova. "The Effect Of Gypsum Content And Seasonal Variations On The Enzyme Activity And Respiration Properties Of Heavy Soils In Reclamation Status." American Journal of Agriculture and Biomedical Engineering 03, no. 06 (June 18, 2021): 61–65. http://dx.doi.org/10.37547/tajabe/volume03issue06-09.

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This article discusses the effect of gypsum content and seasonal variations on the enzyme activity and respiration properties of bad melioration content of soil in Uzbekistan. Furthermore, this paper provides some datas about their origins and how to eliminate it.

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Zhang, Quan, Hui-Min Lei, and Da-Wen Yang. "Seasonal variations in soil respiration, heterotrophic respiration and autotrophic respiration of a wheat and maize rotation cropland in the North China Plain." Agricultural and Forest Meteorology 180 (October 2013): 34–43. http://dx.doi.org/10.1016/j.agrformet.2013.04.028.

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HOLT, P. E. "‘Simultaneous’ urethral pressure profilometry: variations in intravesical pressure with respiration." Research in Veterinary Science 47, no. 1 (July 1989): 117–18. http://dx.doi.org/10.1016/s0034-5288(18)31241-4.

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Hossen, M. S., M. Mano, A. Miyata, M. A. Baten, and T. Hiyama. "Seasonality of ecosystem respiration in a double-cropping paddy field in Bangladesh." Biogeosciences Discussions 8, no. 4 (August 26, 2011): 8693–721. http://dx.doi.org/10.5194/bgd-8-8693-2011.

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Abstract. Ecosystem respiration (RE) from cultivated ecosystems is important for understanding the role of these ecosystems in the global carbon balance. To evaluate carbon dynamics in a double-rice cropping paddy field, we conducted long-term measurements at Mymensingh, Bangladesh in 2007 using a tower-based eddy covariance technique. The study objectives were to investigate the diurnal and seasonal variations in RE and to develop and evaluate empirical models for predicting variations in RE using environmental parameters. We found that the diurnal pattern of RE was driven by soil temperature (Ts) whereas the seasonal variation in RE was controlled primarily by Ts and soil water content (SWC). Under high biomass conditions, Ts plays a dominant role in the magnitude of CO2 release. Both the amount and magnitude of RE variation were larger in the "Boro" dry-season rice growing period from late winter to mid-summer than in the "Aman" wet-season rice growing period from late summer to early winter. Annually, the ratio of RE to gross primary production (GPP) was 0.67, indicating a net sink of carbon; the two growing seasons had RE/GPP ratios of 0.58 and 0.52. A model using Ts, SWC, and aboveground biomass predicted daily RE with R2 values of 0.87 and 0.62 for the Boro and Aman seasons, respectively.

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Resgalla Jr., C., E. S. Brasil, and L. C. Salomão. "Physiological rates in different classes of sizes of Perna perna (Linnaeus, 1758) submmited to experimental loboratory conditions." Brazilian Journal of Biology 66, no. 1b (February 2006): 325–36. http://dx.doi.org/10.1590/s1519-69842006000200015.

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Physiological studies of the mussel Perna perna in Brazil are almost 30 years behind those of other, more exhaustively investigated species, such as Mytilus edulis. Little is known about the variations in physiological rates due to size and the consequences of maintaining P. perna in laboratory conditions. This work investigated the variations in respiration, clearance, excretion and absorption efficiency rates of P. perna, classified by size and acclimatized in a laboratory, monitoring the mussels’ respiration rates and biometry over a period of 30 days, in laboratory conditions. The respiration, clearance and excretion rates presented an allometric relation with the dry weight of the organisms, with b values of 0.66, 0.48 and 0.91 respectively. On the other hand, these same rates, when considered by weight (specific rates) showed a relationship that was inverse to the size of the organisms. Only the absorption efficiency was independent of the weight of the mussel. In terms of acclimatization, it was observed that it takes 10 days for the respiration rate of the mussel P. perna to stabilize in laboratory conditions, after which it follows a routine metabolism.

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Liu, Yuli, Guomo Zhou, Huaqiang Du, Frank Berninger, Fangjie Mao, Xuejian Li, Liang Chen, Lu Cui, Yangguang Li, and Di’en Zhu. "Soil respiration of a Moso bamboo forest significantly affected by gross ecosystem productivity and leaf area index in an extreme drought event." PeerJ 6 (October 31, 2018): e5747. http://dx.doi.org/10.7717/peerj.5747.

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Moso bamboo has large potential to alleviate global warming through carbon sequestration. Since soil respiration (Rs) is a major source of CO2 emissions, we analyzed the dynamics of soil respiration (Rs) and its relation to environmental factors in a Moso bamboo (Phllostachys heterocycla cv. pubescens) forest to identify the relative importance of biotic and abiotic drivers of respiration. Annual average Rs was 44.07 t CO2 ha−1 a−1. Rs correlated significantly with soil temperature (P < 0.01), which explained 69.7% of the variation in Rs at a diurnal scale. Soil moisture was correlated significantly with Rs on a daily scale except not during winter, indicating it affected Rs. A model including both soil temperature and soil moisture explained 93.6% of seasonal variations in Rs. The relationship between Rs and soil temperature during a day showed a clear hysteresis. Rs was significantly and positively (P < 0.01) related to gross ecosystem productivity and leaf area index, demonstrating the significance of biotic factors as crucial drivers of Rs.

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Stefanidis, Konstantinos, and Elias Dimitriou. "Differentiation in Aquatic Metabolism between Littoral Habitats with Floating-Leaved and Submerged Macrophyte Growth Forms in a Shallow Eutrophic Lake." Water 11, no. 2 (February 6, 2019): 287. http://dx.doi.org/10.3390/w11020287.

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The metabolic balance between gross primary production (GPP) and ecosystem respiration (R) is known to display large spatial and temporal variations within shallow lakes. Thus, although estimation of aquatic metabolism using free-water measurements of dissolved oxygen concentration has become increasingly common, the explanation of the variance in the metabolic regime remains an extremely difficult task. In this study, rates of GPP, respiration (R) and the metabolic balance (net ecosystem production, NEP) were estimated in four littoral habitats with different macrophyte growth forms (floating-leaved vs submerged) over a 28-month period in lake of Kastoria (Greece), a shallow eutrophic lake. Our results showed that net heterotrophy prevailed over the studied period, suggesting that allochthonous organics fuel respiration processes in the littoral. Temporal variation in the metabolic rates was driven mainly by the seasonal variation in irradiance and water temperature, with the peak of metabolic activity occurring in summer and early autumn. Most importantly, significant spatial variation among the four habitats was observed and associated with the different macrophyte growth forms that occurred in the sites. The results highlight the importance of habitat specific characteristics for the assessment of metabolic balance and underline the potentially high contribution of littoral habitats to the whole lake metabolism.

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Wu, Juying, Zhuo Pang, Tiejun Sun, Haiming Kan, Wei Hu, and Xiaona Li. "Soil respiration simulation based on soil temperature and water content in artificial smooth brome grassland." Rangeland Journal 38, no. 6 (2016): 579. http://dx.doi.org/10.1071/rj16023.

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Correctly quantifying the relationships between soil respiration and environmental factors and their sources of variability is essential to predict future carbon fluxes and climate feedback. Soil water conditions and soil temperature strongly affect soil respiration and the dynamics of soil organic matter. Despite this, simulation of soil respiration (Rs) based on soil temperature (Ts) and soil volumetric water content (θ) must still be improved, as demonstrated by its discrepant model performance among different seasons. With the objective of gaining a further understanding of the relationships of Rs with Ts and θ and providing an improved model to simulate Rs variations, we measured hourly Rs, Ts and θ using the chamber technique in artificial smooth brome grassland for analysis. We began by dividing the four seasons of a year according to the daily mean air temperature, followed by representing the seasonal variation of Rs, Ts and θ. We found that Rs correlated significantly with Ts in an exponential relationship and with θ in a parabolic relationship seasonally, where the determination coefficient of the Rs-θ relationship was significantly larger than that of the Rs-Ts relationship. We also discovered that the shape of the Rs-θ relationship was seasonally dependent because the optimal θ and the width of the peak Rs around the optimal θ were seasonally specific. Finally, by considering seasonality, the combinational simulation model explained more variation of soil respiration. Thus, seasonality should be considered for more reliable model simulations of soil respiration. These findings are relevant for more accurate predictions and modelling of soil respiration, particularly in temperate artificial grasslands with a continental monsoon climate, where the ‘Birch effect’ strengthens seasonality, and these findings further our understanding of changes in the rates of soil carbon losses as artificial grassland is established.

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Knohl, Alexander, Roland A. Werner, Willi A. Brand, and Nina Buchmann. "Short-term variations in ?13C of ecosystem respiration reveals link between assimilation and respiration in a deciduous forest." Oecologia 142, no. 1 (September 17, 2004): 70–82. http://dx.doi.org/10.1007/s00442-004-1702-4.

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DeVries, Tim, and Curtis Deutsch. "Large-scale variations in the stoichiometry of marine organic matter respiration." Nature Geoscience 7, no. 12 (November 24, 2014): 890–94. http://dx.doi.org/10.1038/ngeo2300.

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Catoni, R., L. Varone, and L. Gratani. "Variations in leaf respiration across different seasons for Mediterranean evergreen species." Photosynthetica 51, no. 2 (June 1, 2013): 295–304. http://dx.doi.org/10.1007/s11099-013-0026-1.

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Jekabsons, Mika B., Francine M. Gregoire, Nancy A. Schonfeld-Warden, Craig H. Warden, and B. A. Horwitz. "T3 stimulates resting metabolism and UCP-2 and UCP-3 mRNA but not nonphosphorylating mitochondrial respiration in mice." American Journal of Physiology-Endocrinology and Metabolism 277, no. 2 (August 1, 1999): E380—E389. http://dx.doi.org/10.1152/ajpendo.1999.277.2.e380.

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The molecular basis for variations in resting metabolic rate (RMR) within a species is unknown. One possibility is that variations in RMR occur because of variations in uncoupling protein 2 (UCP-2) and uncoupling protein 3 (UCP-3) expression, resulting in mitochondrial proton leak differences. We tested the hypothesis that UCP-2 and -3 mRNAs positively correlate with RMR and proton leak. We treated thyroidectomized and sham-operated mice with triiodothyronine (T3) or vehicle and measured RMR, liver, and skeletal muscle mitochondrial nonphosphorylating respiration and UCP-2 and -3 mRNAs. T3 stimulated RMR and liver UCP-2 and gastrocnemius UCP-2 and -3 expression. Mitochondrial respiration was not affected by T3 and did not correlate with UCP-2 and -3 mRNAs. Gastrocnemius UCP-2 and -3 expression did correlate with RMR. We conclude 1) T3 did not influence intrinsic mitochondrial properties such as membrane structure and composition, and 2) variations in UCP-2 and -3 expression may partly explain variations in RMR. One possible explanation for these data is that T3 stimulates the leak in vivo but not in vitro because a posttranslational regulator of UCP-2 and -3 is not retained in the mitochondrial fraction.

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Zhang, Huan, Yanhong Liu, Zhiyong Zhou, and Yueying Zhang. "Inorganic Nitrogen Addition Affects Soil Respiration and Belowground Organic Carbon Fraction for a Pinus tabuliformis Forest." Forests 10, no. 5 (April 28, 2019): 369. http://dx.doi.org/10.3390/f10050369.

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The capability of forest ecosystems to sequester carbon from the atmosphere largely depends on the interaction of soil organic matter and nitrogen, and thus, this process will be greatly influenced by nitrogen deposition under the future scenario of global change. To clarify this interaction, the current study explored the variations in soil carbon fraction and soil respiration with different levels of nitrogen deposition. NH4NO3 was added at concentrations of 0, 50, 100, 200, and 400 kg N ha−1 year−1 separately on twenty 100 m2 plots in a Pinus tabuliformis Carr forest in northern China. Soil samples were analyzed for their nutrient content and biophysical properties two years after nitrogen application, and the soil respiration rate was measured every month during the study period. Seasonal variation and nitrogen addition significantly affected soil respiration rate. On average, nitrogen addition significantly reduced the annual soil respiration rate by 23.74%. Fine root biomass significantly decreased by an average of 43.55% in nitrogen treatment plots compared to the control plot. However, the average proportions of autumn and winter soil respiration rates out of the annual cumulative soil respiration rate greatly increased from 23.57% and 11.04% to 25.90% and 12.18%, respectively. The soil microbial biomass carbon content in the control plot was 342.39 mg kg−1, 23.50% higher than the average value in nitrogen treatment plots. The soil dissolved organic carbon was reduced by 22.60%, on average, following nitrogen addition. Significant correlations were detected between fine root biomass and the annual cumulative soil respiration rate, soil microbial biomass carbon content, and soil dissolved organic carbon content. This demonstrates that nitrogen addition affects soil organic carbon transformation and carbon emission, mainly by depressing fine root production.

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Wang, Ben, Tian Shan Zha, Xin Jia, Jin Nan Gong, Charles Bourque, Wei Feng, Yun Tian, Bin Wu, Yu Qing Zhang, and Heli Peltola. "Soil water regulates the control of photosynthesis on diel hysteresis between soil respiration and temperature in a desert shrubland." Biogeosciences 14, no. 17 (September 7, 2017): 3899–908. http://dx.doi.org/10.5194/bg-14-3899-2017.

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Abstract. Explanations for the occurrence of hysteresis (asynchronicity) between diel soil respiration (Rs) and soil temperature (Ts) have evoked both biological and physical mechanisms. The specifics of these explanations, however, tend to vary with the particular ecosystem or biome being investigated. So far, the relative degree of control of biological and physical processes on hysteresis is not clear for drylands. This study examined the seasonal variation in diel hysteresis and its biological control in a desert-shrub ecosystem in northwest (NW) China. The study was based on continuous measurements of Rs, air temperature (Ta), temperature at the soil surface and below (Tsurf and Ts), volumetric soil water content (SWC), and photosynthesis in a dominant desert shrub (i.e., Artemisia ordosica) over an entire year in 2013. Trends in diel Rs were observed to vary with SWC over the growing season (April to October). Diel variations in Rs were more closely associated with variations in Tsurf than with photosynthesis as SWC increased, leading to Rs being in phase with Tsurf, particularly when SWC > 0.08 m3 m−3 (ratio of SWC to soil porosity = 0.26). However, as SWC decreased below 0.08 m3 m−3, diel variations in Rs were more closely related to variations in photosynthesis, leading to pronounced hysteresis between Rs and Tsurf. Incorporating photosynthesis into a Q10-function eliminated 84.2 % of the observed hysteresis, increasing the overall descriptive capability of the function. Our findings highlight a high degree of control by photosynthesis and SWC in regulating seasonal variation in diel hysteresis between Rs and temperature.

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Sasmita, Aryo, Isnaini Isnaini, and Ulimaz Almira. "PENGARUH PENAMBAHAN BIOCHAR CANGKANG SAWIT DENGAN VARIASI SUHU PIROLISIS TERHADAP EMISI CO2 DARI TOP SOIL." Jurnal Tanah dan Sumberdaya Lahan 9, no. 2 (July 1, 2022): 439–46. http://dx.doi.org/10.21776/ub.jtsl.2022.009.2.25.

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Soil respiration activity is one of the contributors to carbon dioxide (CO2) emissions from the agricultural sector. The agricultural sector can also reduce the CO2 emissions it produces, one of which is by making biochar from agricultural waste. Palm shells have potential as raw materials for biochar because they contain hemicellulose, cellulose and lignin. The purpose of this study was to study the effect of adding biochar with variations in pyrolysis temperature on CO2 emissions resulting from the soil respiration process. Palm shell biochar was pyrolyzed with temperature variations of 500 oC and 600 oC for 1 hour and activated using NaOH. Biochar was then added to the soil at a dose of 10% and incubated for 25 days which was tested once every five days. The results showed that the highest CO2 emissions occurred from soil respiration activities with the addition of palm shell biochar at a temperature of 600 oC at an incubation time of 5 days, which was 37 mg CO2. This value was 22.95% greater than the control treatment without the addition of biochar.

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Lee, Hyun Jeong, Ji Woon Yea, and Se An Oh. "Reductions in the variations of respiration signals for respiratory-gated radiotherapy when using the video-coaching respiration guiding system." Journal of the Korean Physical Society 67, no. 1 (July 2015): 163–69. http://dx.doi.org/10.3938/jkps.67.163.

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Holmqvist, Fredrik, Martin Stridh, Johan E. P. Waktare, Johan Brandt, Leif Sörnmo, Anders Roijer, and Carl J. Meurling. "Rapid fluctuations in atrial fibrillatory electrophysiology detected during controlled respiration." American Journal of Physiology-Heart and Circulatory Physiology 289, no. 2 (August 2005): H754—H760. http://dx.doi.org/10.1152/ajpheart.00075.2005.

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Heart rate during sinus rhythm is modulated through the autonomic nervous system, which generates short-term oscillations. The high-frequency components in these oscillations are associated with respiration, causing sinus arrhythmia, mediated by the parasympathetic nervous system. In this study, we evaluated whether slow, controlled respiration causes cyclic fluctuations in the frequency of the fibrillating atria. Eight patients (four women; median age 63 yr, range 53–68 yr) with chronic atrial fibrillation (AF) and third-degree atrioventricular block treated by permanent pacemaker were studied. ECG was recorded during baseline rest, during 0.125-Hz frequency controlled respiration, and finally during controlled respiration after full vagal blockade. We calculated fibrillatory frequency using frequency analysis of the fibrillatory ECG for overlapping 2.5-s segments; spectral analysis of the resulting frequency trend was performed to determine the spectrum of variations of fibrillatory frequency. Normalized spectral power at respiration frequency increased significantly during controlled respiration from 1.4 (0.76–2.0) (median and range) at baseline to 2.7 (1.2–5.8) ( P = 0.01). After vagal blockade, the power at respiration frequency decreased to 1.2 (0.23–2.8) ( P = 0.01). Controlled respiration causes cyclic fluctuations in the AF frequency in patients with long-duration AF. This phenomenon seems to be related to parasympathetic modulations of the AF refractory period.

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Sharma, Neerja, Rabindra K. Nayak, Vinay K. Dadhwal, Yogesh Kant, and Meer M. Ali. "Temporal Variations of Atmospheric CO2 in Dehradun, India during 2009." Air, Soil and Water Research 6 (January 2013): ASWR.S10590. http://dx.doi.org/10.4137/aswr.s10590.

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The present study reports the temporal variations of CO2 mixing ratio measured using Vaisala GMP-343 sensor (at 15 m height) in Dehradun (30.1 °N, 77.4 °E) during 2009. Being a valley station, the mixing ratios are controlled by biospheric processes but not by large scale transport phenomenon or local pollution. A distinct diurnal cycle varies from 317.9 ppm in the afternoon to 377.2 ppm in the morning (before sunrise). The minimum early morning (0700-1000 IST) drop and minimum afternoon (1300-1700 IST) trough observed during monsoon months are related to the enhanced vegetation activity due to rain at the site. The maximum night time (2200 IST to next day 0700 IST) build up of CO2 observed during monsoon season is associated with the increase in heterotrophic respiration due to high moisture content in the soil. This is also confirmed by the positive coherence between night time CO2 mixing ratio with soil respiration simulated from Carnagie-Ames-Standford Approach (CASA) model. The strong negative coherence with net ecosystem productivity (simulated from the same model) shows that observations captured the regional changes in emission and uptake of CO2 in atmosphere.

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Dhital, Deepa, Tomoharu Inoue, and Hiroshi Koizumi. "Seasonal/Interannual Variations of Carbon Sequestration and Carbon Emission in a Warm-Season Perennial Grassland." Journal of Ecosystems 2014 (November 11, 2014): 1–13. http://dx.doi.org/10.1155/2014/729294.

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Carbon sequestration and carbon emission are processes of ecosystem carbon cycling that can be affected while land area converted to grassland resulting in increased soil carbon storage and below-ground respiration. Discerning the importance of carbon cycle in grassland, we aimed to estimate carbon sequestration in photosynthesis and carbon emission in respiration from soil, root, and microbes, for four consecutive years (2007–2010) in a warm-season perennial grassland, Japan. Soil carbon emission increased with increasing growing season temperature which ranged from 438 to 1642 mg CO2 m−2 h−1. Four years’ average soil carbon emission for growing season, nongrowing season, and annual emission was 1123, 364, and 1488 g C m−2, respectively. Nongrowing and snow covered season soil carbon emission contributed 23–25% and 14–17% to the annual emission. Above-ground biomass varied seasonally and variation in green biomass affected soil carbon emission with increasing temperature and precipitation. Temperature effect on root carbon emission contributed about 1/4th of the total soil carbon emission. Variation in soil and root carbon emission is affected by below-ground biomass. Long-term estimation concluded that seasonal and interannual variations in carbon sequestration and emission are very common in grassland ecosystem.

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Ewel, Katherine C., Wendell P. Cropper.Jr., and Henry L. Gholz. "Soil CO2 evolution in Florida slash pine plantations. II. Importance of root respiration." Canadian Journal of Forest Research 17, no. 4 (April 1, 1987): 330–33. http://dx.doi.org/10.1139/x87-055.

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Respiration of live roots was the single largest contributor to soil CO2 evolution in two mature slash pine (Pinuselliottii) plantations. Root respiration accounted for 51% of soil CO2 evolution at the 9-year-old plantation and 62% at the 29-year-old plantation. Additional estimates, calculated from data recorded from two small trenched plot sites at the 29-year-old plantation and based on possible variations in initial root biomass and subsequent decomposition rates, also averaged 62% of soil CO2 evolution. Specific root respiration averaged 0.40 g•g−1•year−1, varying from 0.34 to 1.70 g•g−1•year−1. Plots with larger proportions of fine roots had faster soil CO2 evolution rates.

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Wilcock, R. J., and J. W. Nagels. "Effects of aquatic macrophytes on physico-chemical conditions of three contrasting lowland streams: a consequence of diffuse pollution from agriculture?" Water Science and Technology 43, no. 5 (March 1, 2001): 163–68. http://dx.doi.org/10.2166/wst.2001.0277.

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Three lowland streams in developed pasture catchments with different farming intensities exhibited contrasting summer diurnal variations in pH, DO and temperature. These are ascribed to differences in dominant aquatic vegetation and their respective effects on shade, and on photosynthetic production and respiration within each stream. The stream dominated by submerged macrophytes had the greatest amplitude swings in DO and pH, and DO levels of 86–128% saturation. Floating marginal macrophytes reduced photosynthetic inputs while providing additional organic loading for respiration, with consequent flat DO and pH curves and conditions not conducive to healthy stream ecosystems. The third stream was shaded by riparian plants, which inhibited photosynthetic effects on DO and pH so that diurnal variation was intermediate between the other two streams. The interaction between nutrients and increased insolation in agricultural catchments, in stimulating aquatic plants, needs to be better understood for managing the sustainability of stream habitats and ecosystems.

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Macor, F., R. Fagard, J. Vanhaecke, and A. Amery. "Respiratory-related blood pressure variability in patients after heart transplantation." Journal of Applied Physiology 76, no. 5 (May 1, 1994): 1961–62. http://dx.doi.org/10.1152/jappl.1994.76.5.1961.

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Our objective was to study whether the variations of blood pressure synchronous with respiration depend on the simultaneous changes of heart rate. Power spectral analysis of the heart period or R-R interval, blood pressure, and respiratory activity was performed by fast Fourier transform during 30 min of supine rest in 12 patients between 16 and 23 days after orthotopic heart transplantation and in 12 age- and sex-matched normal control subjects. The components of the variations of the R-R interval and blood pressure associated with respiration [high-frequency (HF) components] were derived from the power spectra. The HF component of the power spectrum of the R-R interval was almost absent in the transplanted patients compared with the control subjects (2.9 vs. 104 ms2; P < 0.001), whereas the HF component of the power spectrum of blood pressure was not significantly different between the two groups (1.72 vs. 1.65 mmHg2 for systolic and 0.35 vs. 0.60 mmHg2 for diastolic blood pressure). Respiratory variations of both systolic and diastolic blood pressure in humans can depend only slightly on the respiratory heart rate variations.

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Saurette, Daniel D., Scott X. Chang, and Barb R. Thomas. "Autotrophic and heterotrophic respiration rates across a chronosequence of hybrid poplar plantationsin northern Alberta." Canadian Journal of Soil Science 88, no. 3 (May 2, 2008): 261–72. http://dx.doi.org/10.4141/cjss07005.

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Distinction of autotrophic (root, Rr) versus heterotrophic (Rh) soil respiration is important to understanding C balance in forest ecosystems and the contribution of both respiration components to total soil respiration (Rs) may change as stands mature. We studied Rr and Rh in a chronosequence of hybrid poplar plantations that were 4, 6, 8, and 13 yr old in summer 2005. We hypothesized that Rr will become increasingly larger and will also represent a greater proportion of Rs as plantation age increases. Our results showed that both Rs and Rh showed significant seasonal variations; however,Rr were much more variable. No significant differences among plantation ages were observed for any of the respiration parameters (Rr, Rh and Rs) measured throughout the summer. No significant differences were found for the contribution of Rh to Rs between plantation ages or between sampling dates. The average proportion of Rh to Rs across all sites and sampling dates was 0.63 ± 0.026 (mean ± standard error), indicating that heterotrophic respiration dominated total soil respiration in the studied hybrid poplar plantations.The power of the statistical tests in this study was likely quite low due to the inclusion of only two replicates for each plantation age. Key words: Autotrophic, heterotrophic respiration, root exclusion, trenching, hybrid poplar, chronosequence

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Li, P., Y. Yang, and J. Fang. "Variations of root and heterotrophic respiration along environmental gradients in China's forests." Journal of Plant Ecology 6, no. 5 (September 20, 2013): 358–67. http://dx.doi.org/10.1093/jpe/rtt009.

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BURGGREN, WARREN W. "Respiration and Circulation in Land Crabs: Novel Variations on the Marine Design." American Zoologist 32, no. 3 (June 1992): 417–27. http://dx.doi.org/10.1093/icb/32.3.417.

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Wang, Chao, Fei Ren, Xuhui Zhou, Wenhong Ma, Cunzhu Liang, Jinzhou Wang, Jianwei Cheng, Huakun Zhou, and Jin-Sheng He. "Variations in the nitrogen saturation threshold of soil respiration in grassland ecosystems." Biogeochemistry 148, no. 3 (April 2020): 311–24. http://dx.doi.org/10.1007/s10533-020-00661-y.

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Ceschia, �ric, Claire Damesin, St�phanie Lebaube, Jean-Yves Pontailler, and �ric Dufr�ne. "Spatial and seasonal variations in stem respiration of beech trees (Fagus sylvatica)." Annals of Forest Science 59, no. 8 (December 2002): 801–12. http://dx.doi.org/10.1051/forest:2002078.

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Moroni, M. T., P. Q. Carter, and D. A. J. Ryan. "Harvesting and slash piling affects soil respiration, soil temperature, and soil moisture regimes in Newfoundland boreal forests." Canadian Journal of Soil Science 89, no. 3 (May 2, 2009): 343–55. http://dx.doi.org/10.4141/cjss08027.

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The effect of harvesting and slash piling on soil respiration, temperature and moisture was examined in a balsam fir (Abies balsamea) and a black spruce (Picea marinara) forest located in western Newfoundland, Canada, 2 mo to 2.5 yr following harvesting. Within 4 mo of harvesting, soil temperature, moisture, and soil respiration rates were affected by harvesting and slash piling. Clearcut areas without slash (CC-S) had significantly lower soil respiration rates than uncut forests (F). However, clearcut areas with slash cover (CC+S) had significantly higher soil respiration rates than CC-S. When harvested areas with and without slash were combined, harvesting decreased soil respiration in the black spruce forest but had no effect on soil respiration in the balsam fir forest. Harvesting increased soil temperatures at 10 cm, however CC+S temperatures were cooler than CC-S temperatures. Harvested areas tended to dry faster than F, although soil moisture levels at >3.5 cm were not significantly depleted. However, there was evidence of soil drying at <3.5 cm. Soil temperature (at 10 cm) at the time of measurement was most strongly correlated to rates of soil respiration. Temporal variability and treatment effects (harvesting and slash piling) played a minor role in explaining soil respiration rates when variations in soil respiration were adjusted for 10-cm soil temperature,. Soil moisture levels (3.5-9.5 cm depth), which did not vary widely, also played a minor role in explaining soil respiration rates.Key words: Clearcut, Abies balsamea, Picea marinara, carbon dioxide, greenhouse gas

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Liu, Xiaozhong, and Bingru Huang. "Seasonal Changes and Cultivar Difference in Turf Quality, Photosynthesis, and Respiration of Creeping Bentgrass." HortScience 36, no. 6 (October 2001): 1131–35. http://dx.doi.org/10.21273/hortsci.36.6.1131.

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Summer decline in turf quality of creeping bentgrass (Agrostis palustris Hud.) is a major problem in golf course green management. The objective of this study was to examine whether seasonal changes and cultivar variations in turf performance are associated with changes in photosynthesis and respiration rates for creeping bentgrass. The study was conducted on a USGA-specification putting green in Manhattan, Kans., during 1997 and 1998. Four creeping bentgrass cultivars, `L-93', `Crenshaw', `Penncross', and `Providence', were examined. Grasses were mowed daily at 4 mm and irrigated on alternate days to replace 100% of daily water loss. In both years, turf quality, canopy net photosynthetic rate (Pn), and leaf photochemical efficiency (Fv/Fm) were high in May and June and decreased to the lowest levels in July through September. Whole-plant respiration rate (R) and canopy minus air temperature (▵T) increased during summer months. In October, turf quality and Pn increased, whereas R and T decreased. During summer months, turf quality was highest for `L-93', lowest for `Penncross', and intermediate for `Providence' and `Crenshaw'. Seasonal changes and cultivar variations in turf quality were associated with the decreasing photosynthetic rate and increasing respiration rate.

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Widjaja, Devy, Michele Orini, Elke Vlemincx, and Sabine Van Huffel. "Cardiorespiratory Dynamic Response to Mental Stress: A Multivariate Time-Frequency Analysis." Computational and Mathematical Methods in Medicine 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/451857.

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Abstract:

Mental stress is a growing problem in our society. In order to deal with this, it is important to understand the underlying stress mechanisms. In this study, we aim to determine how the cardiorespiratory interactions are affected by mental arithmetic stress and attention. We conduct cross time-frequency (TF) analyses to assess the cardiorespiratory coupling. In addition, we introduce partial TF spectra to separate variations in the RR interval series that are linearly related to respiration from RR interval variations (RRV) that are not related to respiration. The performance of partial spectra is evaluated in two simulation studies. Time-varying parameters, such as instantaneous powers and frequencies, are derived from the computed spectra. Statistical analysis is carried out continuously in time to evaluate the dynamic response to mental stress and attention. The results show an increased heart and respiratory rate during stress and attention, compared to a resting condition. Also a fast reduction in vagal activity is noted. The partial TF analysis reveals a faster reduction of RRV power related to (3 s) than unrelated to (30 s) respiration, demonstrating that the autonomic response to mental stress is driven by mechanisms characterized by different temporal scales.

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Journal articles on the topic 'Respiration variations'

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