The influence of precipitation pulses on soil respiration – Assessing the “Birch effect” by stable carbon isotopes

Unger, Stephan; Máguas, Cristina; Pereira, J. S.; David, Teresa S.; Werner, Christiane

doi:10.1016/j.soilbio.2010.06.019

Cited by 215 publications

(164 citation statements)

References 69 publications

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“…For example, Carbone et al (2011) showed that root respiration was more responsive to seasonal changes in soil moisture, while microbial respiration dominated the response to episodic wetting in a Mediterranean pine forest, using a natural abundance 14 C method for source partitioning. Other studies using isotopic (Unger et al, 2010;Casals et al, 2011) or non-isotopic (Liu et al, 2002;Yan et al, 2010) methods for source partitioning also found similar results. Rhizosphere respiration is dependent on substrate input from recent photosynthesis (Högberg et al, 2001;Kuzyakov and Cheng, 2001), which should be less affected by shortterm soil moisture dynamics.…”

Section: Do Dryingewetting Cycles Impact Rhizosphere Respiration Andsupporting

confidence: 56%

“…We partitioned cumulative soil respiration during an entire dryingewetting cycle into rhizosphere respiration and SOM decomposition using a continuous 13 C-labeling technique (Cheng and Dijkstra, 2007), estimated cumulative net N mineralization during the whole experimental period using an N-budgeting method (Cheng, 2009), and calculated rhizosphere priming effect as the difference in SOM decomposition between the planted treatment and the unplanted treatment (Kuzyakov, 2002;Cheng and Kuzyakov, 2005). Given that the intensity of drying can affect cumulative C and N mineralization in root-free soils (Borken and Matzner, 2009;Unger et al, 2010), we used two plant species with different transpiration rates to simulate two dryingewetting regimes. Sunflower (Helianthus annuus L.) has relatively high transpiration rate and causes severe soil drying, while soybean (Glycine max L.…”

Section: Introductionmentioning

confidence: 99%

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Impacts of drying–wetting cycles on rhizosphere respiration and soil organic matter decomposition

Zhu

Cheng

2013

Soil Biology and Biochemistry

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a b s t r a c tDryingewetting cycles influence both soil organic matter (SOM) decomposition and rhizosphere processes. Rhizosphere processes also affect SOM decomposition through rhizosphere priming. However, little is known about how dryingewetting cycles regulate SOM decomposition with rhizosphere priming, because most previous studies incubated root-free soils and omitted the rhizosphere effect. To investigate the effect of dryingewetting cycles on SOM decomposition in the presence of plants, we grew sunflower (Helianthus annuus) and soybean (Glycine max) in a sandy loam soil under the treatments of either constant moisture or 12 dryingewetting cycles, and used a continuous 13 C-labeling method to partition soil respiration into rhizosphere respiration and SOM decomposition. We found that compared to the constantly-moist treatment, the severe dryingewetting cycles in soils planted with sunflower significantly reduced shoot biomass (32%), root biomass (52%), rhizosphere respiration (29%), and SOM decomposition (22%), while the moderate dryingewetting cycles in soils planted with soybean did not significantly affect these variables. Moreover, SOM decomposition rates in the planted treatment subjected to constantly-moist or dryingewetting conditions were significantly higher compared with the constantly-moist unplanted treatment, indicating a positive rhizosphere priming effect under both soil moisture regimes. However, dryingewetting reduced the rhizosphere priming of sunflower (69% versus 33%) likely due to lower plant biomass and rhizodeposition, but produced similar rhizosphere priming of soybean (82% versus 85%). Overall, dryingewetting cycles significantly modulated rhizosphere respiration and SOM decomposition, with the magnitude depending on soil drying intensity and plant growth performance.Published by Elsevier Ltd.

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Section: Do Dryingewetting Cycles Impact Rhizosphere Respiration Andsupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Impacts of drying–wetting cycles on rhizosphere respiration and soil organic matter decomposition

Zhu

Cheng

2013

Soil Biology and Biochemistry

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“…The Mediterranean climate is characterized by summer droughts that particularly affect the top soil layers; therefore, rainfall events during these dry periods can trigger abrupt increases in SR that last for days (Bowling et al, 2011;Cisneros-Dozal et al, 2007;Lee et al, 2004;Unger et al, 2010). Lee et al (2004) simulated precipitation and found that hardwood forest floors were very sensitive to changes in moisture in the upper soil layers.…”

Section: Rain Pulse and Drought Effects On Srmentioning

confidence: 99%

Does soil moisture overrule temperature dependence of soil respiration in Mediterranean riparian forests?

et al. 2014

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Abstract. Soil respiration (SR) is a major component of ecosystems' carbon cycles and represents the second largest CO 2 flux in the terrestrial biosphere. Soil temperature is considered to be the primary abiotic control on SR, whereas soil moisture is the secondary control factor. However, soil moisture can become the dominant control on SR in very wet or dry conditions. Determining the trigger that makes soil moisture as the primary control factor of SR will provide a deeper understanding on how SR changes under the projected future increase in droughts. Specific objectives of this study were (1) to investigate the seasonal variations and the relationship between SR and both soil temperature and moisture in a Mediterranean riparian forest along a groundwater level gradient; (2) to determine soil moisture thresholds at which SR is controlled by soil moisture rather than by temperature; (3) to compare SR responses under different tree species present in a Mediterranean riparian forest (Alnus glutinosa, Populus nigra and Fraxinus excelsior). Results showed that the heterotrophic soil respiration rate, groundwater level and 30 cm integral soil moisture (SM 30 ) decreased significantly from the riverside moving uphill and showed a pronounced seasonality. SR rates showed significant differences between tree species, with higher SR for P. nigra and lower SR for A. glutinosa. The lower threshold of soil moisture was 20 and 17 % for heterotrophic and total SR, respectively. Daily mean SR rate was positively correlated with soil temperature when soil moisture exceeded the threshold, with Q 10 values ranging from 1.19 to 2.14; nevertheless, SR became decoupled from soil temperature when soil moisture dropped below these thresholds.

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“…These substrates can be made available by the release of osmolytes from microorganisms that accumulated during the dry period as a result of microbial stress prior to a wetting event, from release of some of the cytoplasmic solutes accumulated during the dry period into the soil solution from lysed cells upon wetting [41,[55][56][57], and from a change in the kinetics of enzyme transport and microbial uptake with increased water availability [51]. The duration and magnitude of elevated respiration rates is strongly related to water content [31,53], microbial physiology, and community structure as influenced by the physical and chemical characteristics of the environment [51], and therefore likely differs between organic and mineral soil horizons [58].…”

Section: Discussionmentioning

confidence: 99%

“…Drier soils have been shown to have a greater magnitude of C loss following wetting events [64,80], as the pulse of CO 2 is dependent upon pre-wetting water content. These findings suggest that more severe drought may increase the magnitude of CO 2 losses [57,81]. When under wet conditions, however, CO 2 losses could be depressed by subsequent rainfall by bringing soils to oxygen-limited levels that inhibit respiration [82,83].…”

Section: Discussionmentioning

confidence: 99%

The Impact of Water Content on Sources of Heterotrophic Soil Respiration

McElligott

Seiler

Strahm

2017

Forests

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Heterotrophic respiration (R H ) is a major flux of CO 2 from forest ecosystems and represents a large source of uncertainty in estimating net ecosystem productivity (NEP) using regional soil respiration (R S ) models. R H from leaf litter (R HL ) may contribute greatly to annual R H estimates, but its contribution may be misrepresented due to the logistical and technical challenges associated with chamber-based field measurements of R HL . The purpose of this study was to evaluate the sensitivity of sources of R H (mineral soil-derived heterotrophic respiration [R HM ] and leaf litter-derived heterotrophic respiration [R HL ]) of a loblolly pine plantation (Pinus taeda L.) to varying soil and litter water content over the course of a dry down event. Additionally, we investigated whether fertilization influenced R HL and R HM to understand how forest nutrient management may impact forest soil carbon (C) dynamics. R HL was measured under dry conditions and at field capacity to evaluate water content controls on R HL , determine the duration of increased CO 2 release following wetting, and evaluate the potential contribution to total R H . We also measured R HM inside collars that excluded plant roots and litter inputs, from field capacity until near-zero R HM rates were attained. We found that R HL was more sensitive to water content than R HM , and increased linearly with increasing litter water content (R 2 = 0.89). The contribution of R HL to R H was greatest immediately following the wetting event, and decreased rapidly to near-zero rates between 3 and 10 days. R HM also had a strong relationship with soil water content (R 2 = 0.62), but took between 200 and 233 days to attain near-zero R HM rates. Fertilization had no effect on R HM (p = 0.657), but significantly suppressed R HL rates after the wetting event (p < 0.009). These results demonstrate that there is great temporal variability in both CO 2 released and the water content of differing sources of R H , and forest fertilization may largely impact forest floor C stocks. This variability may not be captured reliably using conventional weekly to monthly chamber-based field sampling efforts and could lead to over-or underestimation of R H . In the context of climate change, changes in the frequency and intensity of wetting and drying events will likely alter R HL and its contribution to R S . Separate consideration of R H sources and controls, along with increased field sampling frequency using chamber-based methodology under a broader range of specific environmental conditions, are likely needed to reduce variability in R H estimates and improve the accuracy of forest NEP predictions.

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The influence of precipitation pulses on soil respiration – Assessing the “Birch effect” by stable carbon isotopes

Cited by 215 publications

References 69 publications

Impacts of drying–wetting cycles on rhizosphere respiration and soil organic matter decomposition

Impacts of drying–wetting cycles on rhizosphere respiration and soil organic matter decomposition

Does soil moisture overrule temperature dependence of soil respiration in Mediterranean riparian forests?

The Impact of Water Content on Sources of Heterotrophic Soil Respiration

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