scholarly journals Rainfall intensification increases the contribution of rewetting pulses to soil respiration

2020 ◽  
Author(s):  
Stefano Manzoni ◽  
Arjun Chakrawal ◽  
Thomas Fischer ◽  
Joshua P. Schimel ◽  
Amilcare Porporato ◽  
...  

Abstract. Soil drying and wetting cycles promote carbon (C) release through large heterotrophic respiration pulses at rewetting, known as Birch effect. Empirical evidence shows that drier conditions before rewetting and larger changes in soil moisture at rewetting cause larger respiration pulses. Because soil moisture varies in response to rainfall, also these respiration pulses depend on the random timing and intensity of precipitation. In addition to rewetting pulses, heterotrophic respiration continues during soil drying, eventually ceasing when soils are too dry to sustain microbial activity. The importance of respiration pulses in contributing to the overall soil respiration flux has been demonstrated empirically, but no theoretical investigation has so far evaluated how the relative contribution of these pulses may change along climatic gradients or as precipitation regimes shift in a given location. To fill this gap, we start by assuming that rewetting pulses and respiration rates during soil drying can be treated as random variables dependent on soil moisture fluctuations, and develop a stochastic model for soil heterotrophic respiration rates that analytically links the statistical properties of respiration to those of precipitation. Model results show that both the mean rewetting pulse respiration and the mean respiration during drying increase with increasing mean precipitation. However, the contribution of respiration pulses to the total heterotrophic respiration increases with decreasing precipitation frequency and to a lesser degree with decreasing precipitation depth, leading to an overall higher contribution of respiration pulses under future more intermittent and intense precipitation. Moreover, the variability of both components of soil respiration is also predicted to increase under these conditions. Therefore, our results suggest that with future more intermittent precipitation, respiration pulses and the associated nutrient release will intensify and become more variable, contributing more to soil biogeochemical cycling.

2020 ◽  
Vol 17 (15) ◽  
pp. 4007-4023
Author(s):  
Stefano Manzoni ◽  
Arjun Chakrawal ◽  
Thomas Fischer ◽  
Joshua P. Schimel ◽  
Amilcare Porporato ◽  
...  

Abstract. Soil drying and wetting cycles promote carbon (C) release through large heterotrophic respiration pulses at rewetting, known as the “Birch” effect. Empirical evidence shows that drier conditions before rewetting and larger changes in soil moisture at rewetting cause larger respiration pulses. Because soil moisture varies in response to rainfall, these respiration pulses also depend on the random timing and intensity of precipitation. In addition to rewetting pulses, heterotrophic respiration continues during soil drying, eventually ceasing when soils are too dry to sustain microbial activity. The importance of respiration pulses in contributing to the overall soil heterotrophic respiration flux has been demonstrated empirically, but no theoretical investigation has so far evaluated how the relative contribution of these pulses may change along climatic gradients or as precipitation regimes shift in a given location. To fill this gap, we start by assuming that heterotrophic respiration rates during soil drying and pulses at rewetting can be treated as random variables dependent on soil moisture fluctuations, and we develop a stochastic model for soil heterotrophic respiration rates that analytically links the statistical properties of respiration to those of precipitation. Model results show that both the mean rewetting pulse respiration and the mean respiration during drying increase with increasing mean precipitation. However, the contribution of respiration pulses to the total heterotrophic respiration increases with decreasing precipitation frequency and to a lesser degree with decreasing precipitation depth, leading to an overall higher contribution of respiration pulses under future more intermittent and intense precipitation. Specifically, higher rainfall intermittency at constant total rainfall can increase the contribution of respiration pulses up to ∼10 % or 20 % of the total heterotrophic respiration in mineral and organic soils, respectively. Moreover, the variability of both components of soil heterotrophic respiration is also predicted to increase under these conditions. Therefore, with future more intermittent precipitation, respiration pulses and the associated nutrient release will intensify and become more variable, contributing more to soil biogeochemical cycling.


2009 ◽  
Vol 89 (3) ◽  
pp. 343-355 ◽  
Author(s):  
M. T. Moroni ◽  
P. Q. Carter ◽  
D. A.J. Ryan

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


2011 ◽  
Vol 8 (4) ◽  
pp. 6415-6445 ◽  
Author(s):  
M. Aguilos ◽  
K. Takagi ◽  
N. Liang ◽  
Y. Watanabe ◽  
S. Goto ◽  
...  

Abstract. We conducted soil warming experiment in a cool-temperate forest with peat soil in northern Japan, during the snowless seasons of 2007–2009. Our objective was to determine whether or not the heterotrophic respiration rate and the temperature sensitivity would change by soil warming. We elevated the soil temperature by 3 °C at 5 cm depth by means of overhead infrared heaters and continuously measured soil CO2 fluxes by using a fifteen-channel automated chamber system. Trenching treatment was also carried out to separate heterotrophic respiration and root respiration from the total soil respiration. The fifteen chambers were divided into three groups each with five replications for the control, unwarmed-trenched, and warmed-trenched treatments. We found that heterotrophic respiration contributed 71 % of the total soil respiration with the remaining 29 % accounted to autotrophic respiration. Soil warming enhanced heterotrophic respiration by 74 % (mean 6.11 ± 3.07 S.D. μmol m−2 s–1) as compared to the unwarmed-trenched treatment (mean 3.52 ± 1.74 μmol m−2 s–1). Soil CO2 efflux, however, was weakly correlated with soil moisture, probably because the volumetric soil moisture (33–46 %) was within a plateau region for root and microbial activities. The enhancement in heterotrophic respiration with soil warming in our study suggests that global warming will accelerate the loss of carbon from forested peatlands more seriously than other upland forest soils. On the other hand, soil warming did not cause significant change in the temperature sensitivity, Q10, (2.79 and 2.74 determined using hourly efflux data for unwarmed- and warmed-trenched, respectively), but increased their basal respiration rate at 0 °C (0.93 and 1.21 μmol m−2 s−1, respectively). Results suggest that if we predict the soil heterotrophic respiration rate in future warmer environment using the current relationship between soil temperature and heterotrophic respiration, the rate can be underestimated.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Na Lei ◽  
Juan Li ◽  
Tianqing Chen

AbstractSeasonal changes in respiration and the components of four reconstructed soils (gravel + meteorite + lou; gravel + shale + lou; gravel + sand + lou; and gravel + soft rock + lou) in barren gravel land were monitored using the soil carbon flux measurement system. The results showed that (1) the monthly average respiration rate and the rates of the components in the four reconstructed soils were the highest in summer and lowest in winter. In winter, the monthly average respiration rates of the four reconstructed soils were not different (p > 0.05). In summer, the monthly average respiration rate of the sand or meteorite reconstructed soil was different from that of the other three (p < 0.05). (2) The heterotrophic and autotrophic respiration rates were different between the four reconstructed soils (p < 0.05). The contribution of heterotrophic respiration to total respiration in the four reconstructed soils was greater than that of autotrophic respiration throughout the year. In winter, autotrophic respiration accounts for the smallest proportion of total respiration. As the temperature rises, the proportion of autotrophic respiration to total respiration gradually increases and peaks in summer. In summer, the proportion of heterotrophic respiration in the total respiration is the smallest. With the decrease in temperature, the proportion of heterotrophic respiration in total respiration gradually increases and peaks in winter. (3) The maximum and minimum values of the monthly average respiration rate of the four reconstructed soils coincided with the months of maximum and minimum soil temperature. The soil volumetric water content changed with the amount of precipitation. The correlation between soil respiration and temperature was greater than that between soil respiration and volumetric water content. (4) The correlation in seasonal variation between respiration of the four remodelled soils and hydrothermal factors in the study area can be characterised by an exponential function and power-exponential function.


2011 ◽  
Vol 41 (9) ◽  
pp. 1897-1906 ◽  
Author(s):  
Yidong Wang ◽  
Qingkang Li ◽  
Huimin Wang ◽  
Xuefa Wen ◽  
Fengting Yang ◽  
...  

Despite the significance of interannual variation of soil respiration (RS) for understanding long-term soil carbon dynamics, factors that control the interannual variation of RS have not been sufficiently investigated. Interannual variation of RS was studied using a 6-year data set collected in a subtropical plantation dominated by an exotic species, slash pine (Pinus elliottii Engelm.), in China. The results showed that seasonal variation of RS was significantly affected by soil temperature and soil water content (SWC). RS in the dry season (July–October) was constrained by seasonal drought. Mean annual RS was estimated to be 736 ± 30 g C·m–2·year–1, with a range of 706–790 g C·m–2·year–1. Although this forest was characterized by a humid climate with high precipitation (1469 mm·year–1), the interannual variation of RS was attributed to the changes of annual mean SWC (R2 = 0.66, P = 0.03), which was affected by annual rainfall frequency (R2 = 0.80, P < 0.01) and not rainfall amount (P = 0.84). Consequently, precipitation pattern indirectly controlled the interannual variation of RS by affecting soil moisture in this subtropical forest. In the context of climate change, interannual variation of RS in subtropical ecosystems is expected to increase because of the predicted changes of precipitation regime.


2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Tairui Liu ◽  
Daoli Peng ◽  
Zhijie Tan ◽  
Jinping Guo ◽  
Yunxiang Zhang

Abstract Background The carbon pools of forest soils play a vital role in global carbon sequestration and emissions. Forest management can regulate the sequestration and output of forest soil carbon pools to a certain extent; however, the kinetics of the effects of forest density on soil carbon pools require further investigation. Methods We established sample plots with stand density gradients in three different aged Larix principis-rupprechtii plantations and quantified the soil respiration, soil organic carbon (SOC), soil dissolved organic carbon (DOC), microbial biomass carbon (MBC), light fraction organic carbon (LFOC), and readily oxidized carbon (ROC). Results and conclusions During the growth and development of plantations, stand density is an essential factor that impacts soil respiration and its associated elements. Moderate density was observed to promote both the soil and heterotrophic respiration rates and the sequestration of MBC and LFOC, whereas it inhibited the sequestration of ROC. The soil, heterotrophic, and autotrophic respiration rates of older forest stands were relatively rapid, whereas the contents of SOC, MBC, LFOC, DOC, and ROC were higher and more sensitive to changes in stand density. The MBC, LFOC, and ROC in soil labile organic carbon were closely related to both the soil and heterotrophic respiration, but not the SOC. Among them, the LFOC and MBC played the roles of “warehouse” and “tool” and were significantly correlated with soil and heterotrophic respiration. The ROC, as a “raw material”, exhibited a significantly negative correlation with the soil and heterotrophic respiration. When the soil and heterotrophic respiration rates were rapid, the ROC content in the soil maintained the low level of a “dynamically stabilized” state. The stand density regulated heterotrophic respiration by affecting the soil labile organic carbon, which provided an essential path for the stand density to regulate soil respiration.


2010 ◽  
Vol 7 (3) ◽  
pp. 1133-1142 ◽  
Author(s):  
K. Tamai

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.


2009 ◽  
Vol 6 (6) ◽  
pp. 10935-10961
Author(s):  
K. Tamai

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.


2014 ◽  
Vol 618 ◽  
pp. 380-387
Author(s):  
Jiang Ming Ma ◽  
Meng Wu ◽  
Ting Ting Zhan ◽  
Feng Tian ◽  
Shi Chu Liang

This experiment was conducted on the 4 years old Eucalyptus plantation in Beihai of Guangxi, southern China. From January to December 2013, in the spring, summer, autumn and winter, seasonal variation and diurnal variation of the soil respiration and its environmental factors had been observed, respectively. The results showed that: (1) Soil respirations has obvious seasonal characteristics, the soil respiration rate in each seasons showed that: summer> spring > autumn > winter. The heterotrophic respiration rate was higher than the autotrophic respiration rate. The contribution of autotrophic respiration rate in winter was higher than that in other three seasons. (2) Soil respiration has obvious diurnal characteristic, it could be expressed as a single-peak curve. But the maximum value of soil respiration appeared in different times in different seasons. (3) There existed positive correlation index exponential relationships between the soil temperature and the soil respiration rate and its components. Soil temperature changes could explain soil respiration, autotrophic respiration and heterotrophic respiration by 90.2%, 27.5% and 92.8%. Temperature sensitivity showed following order: the heterotrophic respiration rate> the soil respiration rate> the autotrophic respiration rate, in terms of affected by temperature, the heterotrophic respiration was higher than the autotrophic respiration. (4) There were notable positive correlations between soil moisture content and soil respiration rate. Obviously, soil moisture content could promote soil respiration in a certain range.


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