Effect of precipitation on respiration of different reconstructed soils

Abstract

Respiration and hydrothermal characteristics of four reconstructed soils in barren gravel land at a site in Shaanxi Province were monitored before, during, and after two precipitation events. Both precipitation events significantly reduced soil temperature but there were great fluctuations in temperature after the second precipitation event. Moreover, precipitation increased the moisture content of the reconstructed soils. Before the first precipitation event, the soil volumetric water content was relatively stable, while it gradually decreased before the second precipitation event. The first precipitation event significantly stimulated the respiration rate for all reconstructed soils, while the second precipitation event generally inhibited it, especially during the precipitation event. The key factors influencing respiration for different reconstructed soils were different between the precipitation events. When soil volumetric water content showed persistent variation before precipitation, soil moisture was the most influential factor. In contrast, if water content was stable, soil temperature was more influential. Soil moisture and temperature jointly influenced soil respiration before, during, and after the precipitation event, while soil moisture was always the most influential factor after precipitation. Soil respiration is the main component of the carbon cycle in terrestrial ecosystems. It is the second largest source of carbon emissions after atmospheric photosynthesis between the atmosphere and terrestrial ecosystems 1,2. Small changes in soil respiration significantly affected global carbon dynamics 3. A detailed analysis of the dynamics of soil respiration and its controlling factors is of great significance for accurately predicting changes in the carbon cycle under future climate change conditions 4. Soil temperature and soil moisture are the most important environmental factors affecting soil respiration 5,6 , and there is an interaction between the effects of soil temperature and soil moisture on soil respiration. Under conditions of future climate change, precipitation will change greatly, and the frequency of drought and extreme precipitation will increase 7. There are two different views on how precipitation might affect soil respiration. One is that precipitation will strongly and quickly stimulate soil respiration. This pulse is called the 'Birch effect' 8. However, it has been shown that the 'Birch effect' does not apply to all soils, and that for moist to wet soils, precipitation will instead inhibit soil respiration 9. The effect of precipitation on soil respiration is affected by environmental conditions such as soil temperature and moisture, and there is complex relationship of soil respiration with soil temperature and moisture. Several previous studies have demonstrated that there are many factors that could influence the response of soil respiration to precipitation events, including, both antecedent soil moisture and precipitation conditions 10 , different soil temperature and moistu...

Respiration characteristics and its responses to hydrothermal seasonal changes in reconstructed soils

“…The relationships between soil respiration and soil temperature and water content were fitted by an exponential model ( 1 ) and a quadratic curve model ( 2 ), respectively. Additionally, the relationship between soil respiration and both soil temperature and soil volumetric water content was fitted by power-index model ( 3 ) 20 : where R S is the soil respiration rate (μmol m −2 s −1 ); T is the soil temperature (°C); w is the soil volumetric water content (%); a , b , and c are the model parameters.…”

Components of Soil Respiration and Its Temperature Sensitivity in Four Reconstructed Soils

“…Each soil respiration ring was measured 3 times and the measurement time was 4 min. Autotrophic respiration was obtained by subtraction, that is, soil autotrophic respiration should be the difference between soil total respiration sinus heterotrophic respirations [24].…”

“…Nonlinear regression was used to assess the relationship between soil respiration and hydrothermal influence factors of the four reconstructed soils, and Q 10 was estimated. The relationship between soil respiration and soil temperature was fitted by an exponential model (Eq.1) [24]:…”

“…The dosage of meteorite, shale, sand, and soft rock was 1 × 10 -3 m 3 /m 2 . The dimensions of all test plots were 20 × 30 m 2 [24].…”

“…The excavated ditches were partitioned with as oards, and the soil was backfilled according to the profile level. The vegetation on the ground was cut off in soil respiration rings, ensuring that no vegetation grew in soil respiration rings during the observation period [24].…”