Soil moisture and salinity as main drivers of soil respiration across natural xeromorphic vegetation and agricultural lands in an arid desert region

Ecosystem carbon losses from soil microbial respiration are a key component of global carbon cycling, resulting in the transfer of 40–70 Pg carbon from soil to the atmosphere each year. Because these microbial processes can feed back to climate change, understanding respiration responses to environmental factors is necessary for improved projections. We focus on respiration responses to soil moisture, which remain unresolved in ecosystem models. A common assumption of large-scale models is that soil microorganisms respond to moisture in the same way, regardless of location or climate. Here, we show that soil respiration is constrained by historical climate. We find that historical rainfall controls both the moisture dependence and sensitivity of respiration. Moisture sensitivity, defined as the slope of respiration vs. moisture, increased fourfold across a 480-mm rainfall gradient, resulting in twofold greater carbon loss on average in historically wetter soils compared with historically drier soils. The respiration–moisture relationship was resistant to environmental change in field common gardens and field rainfall manipulations, supporting a persistent effect of historical climate on microbial respiration. Based on these results, predicting future carbon cycling with climate change will require an understanding of the spatial variation and temporal lags in microbial responses created by historical rainfall.

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Ecological responses of Stipa steppe in Inner Mongolia to experimentally increased temperature and precipitation. 3. Soil respiration

The Rangeland Journal ◽

10.1071/rj16083 ◽

2018 ◽

Vol 40 (2) ◽

pp. 153 ◽

Cited By ~ 6

Author(s):

Xuexia Wang ◽

Yali Chen ◽

Yulong Yan ◽

Zhiqiang Wan ◽

Ran Chao ◽

...

Keyword(s):

Soil Moisture ◽

Soil Respiration ◽

Soil Temperature ◽

Respiration Rate ◽

Inner Mongolia ◽

Growing Season ◽

Climatic Warming ◽

Soil Respiration Rate ◽

Natural Rainfall ◽

Temperature And Precipitation

The response of soil respiration to simulated climatic warming and increased precipitation was evaluated on the arid–semi-arid Stipa steppe of Inner Mongolia. Soil respiration rate had a single peak during the growing season, reaching a maximum in July under all treatments. Soil temperature, soil moisture and their interaction influenced the soil respiration rate. Relative to the control, warming alone reduced the soil respiration rate by 15.6 ± 7.0%, whereas increased precipitation alone increased the soil respiration rate by 52.6 ± 42.1%. The combination of warming and increased precipitation increased the soil respiration rate by 22.4 ± 11.2%. When temperature was increased, soil respiration rate was more sensitive to soil moisture than to soil temperature, although the reverse applied when precipitation was increased. Under the experimental precipitation (20% above natural rainfall) applied in the experiment, soil moisture was the primary factor limiting soil respiration, but soil temperature may become limiting under higher soil moisture levels.

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Relationships between soil respiration and soil moisture

Soil Biology and Biochemistry ◽

10.1016/j.soilbio.2007.12.012 ◽

2008 ◽

Vol 40 (5) ◽

pp. 1013-1018 ◽

Cited By ~ 94

Author(s):

Freeman J. Cook ◽

Valerie A. Orchard

Keyword(s):

Soil Moisture ◽

Soil Respiration

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Soil moisture modifies the response of soil respiration to temperature in a desert shrub ecosystem

Biogeosciences ◽

10.5194/bg-11-259-2014 ◽

2014 ◽

Vol 11 (2) ◽

pp. 259-268 ◽

Cited By ~ 85

Author(s):

B. Wang ◽

T. S. Zha ◽

X. Jia ◽

B. Wu ◽

Y. Q. Zhang ◽

...

Keyword(s):

Soil Moisture ◽

Soil Respiration ◽

Seasonal Cycle ◽

Northwest China ◽

Interactive Effects ◽

Co2 Efflux ◽

Diel Variation ◽

Desert Ecosystems ◽

Volumetric Soil Water Content ◽

Desert Shrub

Abstract. The current understanding of the responses of soil respiration (Rs) to soil temperature (Ts) and soil moisture is limited for desert ecosystems. Soil CO2 efflux from a desert shrub ecosystem was measured continuously with automated chambers in Ningxia, northwest China, from June to October 2012. The diurnal responses of Rs to Ts were affected by soil moisture. The diel variation in Rs was strongly related to Ts at 10 cm depth under moderate and high volumetric soil water content (VWC), unlike under low VWC. Ts typically lagged Rs by 3–4 h. However, the lag time varied in relation to VWC, showing increased lag times under low VWC. Over the seasonal cycle, daily mean Rs was correlated positively with Ts, if VWC was higher than 0.08 m3 m−3. Under lower VWC, it became decoupled from Ts. The annual temperature sensitivity of Rs (Q10) was 1.5. The short-term sensitivity of Rs to Ts varied significantly over the seasonal cycle, and correlated negatively with Ts and positively with VWC. Our results highlight the biological causes of diel hysteresis between Rs and Ts, and that the response of Rs to soil moisture may result in negative feedback to climate warming in desert ecosystems. Thus, global carbon cycle models should account the interactive effects of Ts and VWC on Rs in desert ecosystems.

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Significance of soil respiration from biological activity in the degradation processes of different types of organic matter

10.37281/drcsf/1.2.10 ◽

2020 ◽

Vol 1 (2) ◽

pp. 171-179

Keyword(s):

Climate Change ◽

Organic Matter ◽

Soil Moisture ◽

Soil Respiration ◽

Soil Temperature ◽

Temperature Sensitivity ◽

Soil Co2 Efflux ◽

Co2 Efflux ◽

Soil Co2 ◽

Total Soil

Soil respiration is a major component of global carbon cycle. Therefore, it is crucial to understand the environmental controls on soil respiration for evaluating potential response of ecosystems to climate change. In a temperate deciduous forest (located in Northern-Hungary) we added or removed aboveground and belowground litter to determine total soil respiration. We investigated the relationship between total soil CO2 efflux, soil moisture, and soil temperature. Soil CO2 efflux was measured at each plot using soda-lime method. Temperature sensitivity of soil respiration (Q10) was monitored via measuring soil temperature on an hourly basis, while soil moisture was determined monthly. Soil respiration increased in control plots from the second year after implementing the treatment, but results showed fluctuations from one year to another. The effect of doubled litter was less significant than the effect of removal. Removed litter and root inputs caused substantial decrease in soil respiration. We found that temperature was more influential in the control of soil respiration than soil moisture. In plots with no litter Q10 varied in the largest interval. For treatment with doubled litter layer, temperature sensitivity of CO2 efflux did not change considerably. The effect of increasing soil temperature is more conspicuous to soil respiration in litter removal treatments since lack of litter causes greater irradiation. When exclusively leaf litter was considered, the effect of temperature on soil respiration was lower in treatments with added litter than with removed litter. Our results reveal that soil life is impacted by the absence of organic matter, rather than by an excess of organic matter. Results of CO2 emission from soils with different organic matter content can contribute to sustainable land use, considering the changed climatic factors caused by global climate change.

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Spatially variable soil water repellency enhances soil respiration rates (CO<sub>2</sub> efflux)

10.5194/bg-2017-79 ◽

2017 ◽

Author(s):

Emilia Urbanek ◽

Stefan H. Doerr

Keyword(s):

Soil Moisture ◽

Soil Respiration ◽

Soil Water ◽

Water Distribution ◽

Preferential Flow ◽

Water Repellency ◽

Water Repellent ◽

Co2 Efflux ◽

Soil Co2 ◽

Soil Water Repellency

Abstract. Soil CO2 emissions are strongly dependent on water distribution in soil pores, which in turn can be affected by soil water repellency (SWR; hydrophobicity). SWR restricts infiltration and movement of water, affecting soil hydrology as well as biological and chemical processes. Effects of SWR on soil carbon dynamics and specifically on soil respiration (CO2 efflux) have been studied in a few laboratory experiments but they remain poorly understood. Existing studies suggest that soil respiration is reduced in water repellent soils, but the responses of soil CO2 efflux to varying water distribution created by SWR are not yet known. Here we report on the first field-based study that tests whether soil water repellency indeed reduces soil respiration, based on in situ field measurements carried out over three consecutive years at a grassland and pine forest site under the humid temperate climate of the UK. CO2 efflux was reduced on occasions when soil exhibited consistently high SWR and low soil moisture following long dry spells. However, the highest respiration rates occurred not when SWR was absent, but when SWR, and thus soil moisture, was spatially patchy, a pattern observed for the majority of the measurement period. This somewhat surprising phenomenon can be explained by SWR-induced preferential flow, directing water and nutrients to microorganisms decomposing organic matter concentrated in hot spots near preferential flow paths. Water repellent zones provide air-filled pathways through the soil, which facilitate soil-atmosphere O2 and CO2 exchanges. This study demonstrates that SWR have contrasting effects on CO2 fluxes and, when spatially-variable, can enhance CO2 efflux. Spatial variability in SWR and associated soil moisture distribution needs to be considered when evaluating the effects of SWR on soil carbon dynamics under current and predicted future climatic conditions.

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Impact of elevated precipitation, nitrogen deposition and warming on soil respiration in a temperate desert

Biogeosciences ◽

10.5194/bg-15-2007-2018 ◽

2018 ◽

Vol 15 (7) ◽

pp. 2007-2019 ◽

Cited By ~ 10

Author(s):

Ping Yue ◽

Xiaoqing Cui ◽

Yanming Gong ◽

Kaihui Li ◽

Keith Goulding ◽

...

Keyword(s):

Soil Moisture ◽

Soil Respiration ◽

Soil Temperature ◽

Carbon Dioxide Emissions ◽

Environmental Changes ◽

N Deposition ◽

Climate Feedback ◽

Single Factor ◽

Extreme Precipitation Events ◽

Temperate Desert

Abstract. Soil respiration (Rs) is the most important source of carbon dioxide emissions from soil to atmosphere. However, it is unclear what the interactive response of Rs would be to environmental changes such as elevated precipitation, nitrogen (N) deposition and warming, especially in unique temperate desert ecosystems. To investigate this an in situ field experiment was conducted in the Gurbantunggut Desert, northwest China, from September 2014 to October 2016. The results showed that precipitation and N deposition significantly increased Rs, but warming decreased Rs, except in extreme precipitation events, which was mainly through its impact on the variation of soil moisture at 5 cm depth. In addition, the interactive response of Rs to combinations of the factors was much less than that of any single-factor, and the main response was a positive effect, except for the response from the interaction of increased precipitation and high N deposition (60 kg N ha−1 yr−1). Although Rs was found to show a unimodal change pattern with the variation of soil moisture, soil temperature and soil NH4+-N content, and it was significantly positively correlated to soil dissolved organic carbon (DOC) and pH, a structural equation model found that soil temperature was the most important controlling factor. Those results indicated that Rs was mainly interactively controlled by the soil multi-environmental factors and soil nutrients, and was very sensitive to elevated precipitation, N deposition and warming. However, the interactions of multiple factors largely reduced between-year variation of Rs more than any single-factor, suggesting that the carbon cycle in temperate deserts could be profoundly influenced by positive carbon–climate feedback.

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