Optimum soil water for soil respiration before and after amendment with glucose in humid tropical acrisols and a boreal mor layer

Ilstedt, Ulrik; Nordgren, Anders; Malmer, Anders

doi:10.1016/s0038-0717(00)00073-0

Cited by 158 publications

(93 citation statements)

References 27 publications

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“…Similarly, no decrease in microbial CO 2 production, and consequently CO 2 evolution, was detected for a type of mineral soil similar to ours nor for a similar type of organic layer, i.e. boreal mor in conditions close to saturation, at water contents exceeding ours (Ilstedt et al, 2000;Schjønning et al, 2003).…”

Section: Response Of Co 2 Efflux To Moisturesupporting

confidence: 73%

Seasonality in a boreal forest ecosystem affects the use of soil temperature and moisture as predictors of soil CO<sub>2</sub> efflux

2011

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Abstract. Our objectives were to identify factors related to temporal variation of soil CO 2 efflux in a boreal pine forest and to evaluate simple predictive models of temporal variation of soil CO 2 efflux. Soil CO 2 efflux was measured with a portable chamber in a Finnish Scots pine forest for three years, with a fourth year for model evaluation. Plot averages for soil CO 2 efflux ranged from 0.04 to 0.90 g CO 2 m −2 h −1 during the snow-free period, i.e. May-October, and from 0.04 to 0.13 g CO 2 m −2 h −1 in winter. Soil temperature was a good predictor of soil CO 2 efflux. A quadratic model of lntransformed efflux explained 76-82 % of the variation over the snow-free period.The results revealed an effect of season: at a given temperature of the organic layer, soil CO 2 efflux was higher later in the snow-free period (in August and September) than in spring and early summer (in May and June). Regression coefficients for temperature (approximations of a Q 10 value) of month-specific models decreased with increasing average soil temperatures. Efflux in July, the month of peak photosynthesis, showed no clear response to temperature or moisture. Inclusion of a seasonality index, degree days, improved the accuracy of temperature response models to predict efflux for the fourth year of measurements, which was not used in building of regression models. During peak efflux from mid-July to late-August, efflux was underestimated with the models that included degree days as well as with the models that did not. The strong influence of the flux of photosynthates belowground and the importance of root respiration could explain the relative temperature insensitivity observed in July and together with seasonality of growth of root and root-associated mycorrhizal fungi could explain partial failure of models to predict magnitude of efflux in the peak season from mid-July to August.Correspondence to: S. M. Niinistö (sini.niinisto@iki.fi)The effect of moisture early in the season was confounded by simultaneous advancement of the growing season and increase in temperature. In a dry year, however, the effect of drought was evident as soil CO 2 efflux was some 30 % smaller in September than in the previous wet year. Soil temperature was a good overall predictor of soil CO 2 efflux, possibly partly because its apparent effect was strengthened by many environmental factors and ecosystem processes that varied in concert with its variation. However, the consistent underestimation by the predictive models for the peak season corroborates recent findings concerning the importance of seasonal changes in carbon inputs to processes producing CO 2 in soil.

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Section: Response Of Co 2 Efflux To Moisturesupporting

confidence: 73%

Seasonality in a boreal forest ecosystem affects the use of soil temperature and moisture as predictors of soil CO<sub>2</sub> efflux

2011

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“…Subsamples were dried at 105°C for 24 h to determine their dry mass, and the OM content was determined by loss on ignition (LOI; 550°C for 6 h). Prior to incubation, the water content of the fresh samples was adjusted to establish a water potential of -25 kPa, which is known to be optimal incubation conditions in similar soil samples (Ilstedt et al 2000). The OM content was 0.93 ± 0.004(SD)kg kg −1 with a C content of 0.53 kg kg −1 and N content of 0.014 kg kg −1 , the C:N ration being 38.…”

Section: Soil Sampling and Processingmentioning

confidence: 99%

The effect of temperature and substrate quality on the carbon use efficiency of saprotrophic decomposition

et al. 2016

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Background and aims Mineralization of soil organic matter (SOM) constitutes a major carbon flux to the atmosphere. The carbon use efficiency (CUE) of the saprotrophic microorganisms mineralizing SOM is integral for soil carbon dynamics. Here we investigate how the CUE is affected by temperature, metabolic conditions, and the molecular complexity of the substrate. Methods We incubated O-horizon soil samples (with either 13 C-glucose or 13 C-cellulose) from a boreal coniferous forest at 4, 9, 14, and 19°C, and calculated CUEs based on the amount of 13 C-CO 2 and 13 C-labelled microbial biomass produced. The effects of substrate, temperature, and metabolic conditions (representing unlimited substrate supply and substrate limitation) on CUE were evaluated. Results CUE from metabolizing glucose was higher as compared to cellulose. A slight decrease in CUE with increasing temperature was observed in glucose amended samples (but only in the range 9-19°C), but not in cellulose amended samples. CUE differed significantly with metabolic conditions, i.e. CUE was higher during unlimited growth conditions as compared to conditions with substrate limitation. Conclusions We conclude that it is integral to account for both differences in CUE during different metabolic phases, as well as complexity of substrate, when interpreting temperature dependence on CUE in incubation studies.

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“…2) is in agreement with many previous studies (Harris, 1981;Killham, 1994) and can be explained by the changes in water and oxygen (O 2 ) availability. In dry soil, water films around aggregates are very thin and water is held tightly on to aggregate surfaces resulting in a lack of water for metabolic activity and diffusion of substrates to the microbes limits their activity (West et al, 1989;Ilstedt et al, 2000). As the water content increases, the thickness of the water film around aggregates increases and small pores become water-filled.…”

Section: Discussionmentioning

confidence: 99%

“…The water content optimal for microbial activity is reached when the soil contains enough water to allow diffusion of substrates to the microbes and enzymes away from them, but large pores are still air-filled to allow gas exchange, i.e. removal of CO 2 from respiration and supply of O 2 since most soil microorganisms are aerobic (Ilstedt et al, 2000). If the water content increases further, gas exchange is impaired because diffusion of gases is 10 3 -10 4 times lower in water than in air (Armstrong, 1979).…”

Section: Discussionmentioning

confidence: 99%

Effects of Rewetting of Air-Dry Soil and Adaptation to Low Matric and Osmotic Potential

Chowdhury¹

2015

International J. of Soil Science

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When conducting incubation experiments to measure soil respiration in response to a given treatment in soils of different texture, it is important to have baseline information about the soils and to ensure that the effect of the storage or pre-incubation conditions on the results are minimized. Three experiments were conducted with up to seven soils (3 non-saline, 4 saline) to investigate (1) The relationship between soil water content or water potential and soil respiration, (2) The time required until soil respiration is stabilized after rewetting of air-dry soil and (3) If pre-incubation at a given matric or osmotic potential changes the response of soil respiration to matric or osmotic potential. The texture of the soils varied from sand to sandy loam. Cumulative respiration showed an optimum curve in response to differential soil water content in all 7 soils, but the maximal cumulative respiration was reached at different water content in the soil, being 45 g kgG 1 for the non-saline sand and 200 g kgG 1 for the non-saline sandy loam. However, when expressed against water potential, maximal cumulative respiration was achieved between 0 and -1 MPa in all soils. Rewetting of air-dry soil induced a flush of respiration in the first 1-2 days, but respiration rates stabilized 7-8 days after rewetting in all soils. Pre-incubation at low matric or osmotic potential for two weeks did not significantly affect soil respiration at low matric or osmotic potential in the following two weeks compared to soils which had been pre-incubated at optimal matric potential and high osmotic potential. In conclusion, when comparing the response of respiration to water availability among soils of different texture it is important to consider water potential and not water content. Furthermore, an adaptation period of 2 weeks does not seem to increase the tolerance of soil respiration to low osmotic or matric potential compared to non-adapted soils.

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Optimum soil water for soil respiration before and after amendment with glucose in humid tropical acrisols and a boreal mor layer

Cited by 158 publications

References 27 publications

Seasonality in a boreal forest ecosystem affects the use of soil temperature and moisture as predictors of soil CO<sub>2</sub> efflux

Seasonality in a boreal forest ecosystem affects the use of soil temperature and moisture as predictors of soil CO<sub>2</sub> efflux

The effect of temperature and substrate quality on the carbon use efficiency of saprotrophic decomposition

Effects of Rewetting of Air-Dry Soil and Adaptation to Low Matric and Osmotic Potential

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Optimum soil water for soil respiration before and after amendment with glucose in humid tropical acrisols and a boreal mor layer

Cited by 158 publications

References 27 publications

Seasonality in a boreal forest ecosystem affects the use of soil temperature and moisture as predictors of soil CO&lt;sub&gt;2&lt;/sub&gt; efflux

Seasonality in a boreal forest ecosystem affects the use of soil temperature and moisture as predictors of soil CO&lt;sub&gt;2&lt;/sub&gt; efflux

The effect of temperature and substrate quality on the carbon use efficiency of saprotrophic decomposition

Effects of Rewetting of Air-Dry Soil and Adaptation to Low Matric and Osmotic Potential

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Seasonality in a boreal forest ecosystem affects the use of soil temperature and moisture as predictors of soil CO<sub>2</sub> efflux

Seasonality in a boreal forest ecosystem affects the use of soil temperature and moisture as predictors of soil CO<sub>2</sub> efflux