Response Of Respiration Research Articles

Contrary responses of soil heterotrophic and autotrophic respiration to spring and summer drought in alfalfa on the Loess Plateau

Climate change has increased the intensity and frequency of seasonal droughts, which could fundamentally affect the terrestrial carbon (C) cycle. However, as the second-largest terrestrial C flux, soil respiration (Rs) and its heterotrophic (Rh) and autotrophic (Ra) components in response to seasonal drought are unclear. To investigate the effect of seasonal drought on the patterns and mechanisms of Rs and its components, a two-year continuous Rs measurement experiment was conducted in typical rain-fed managed alfalfa (Medicago sativa L.) fields on the Loess Plateau in China. The results showed that the ranges of Rs, Rh and Ra in the four seasons of managed alfalfa fields on the Loess Plateau were 0.45–3.70, 0.13–2.27, and 0.33–2.14 μmol m−2 s−1, respectively. There was no significant difference in the average annual Rs between the two years (P > 0.05). Both spring and summer droughts significantly decreased Rs; however, the seasonal Rh and Ra had different patterns under spring and summer droughts. Spring drought significantly reduced the seasonal Rh by 35.19 % but increased Ra by 20.35 %. In contrast, summer drought significantly increased the seasonal Rh by 45.51 % but decreased the Ra by 35.05 %. The differential response of Ra to seasonal drought was attributed to the opposite responses of the leaf area index (LAI) and photosynthetic rate to spring and summer drought, while Rh was related to the contrasting microorganism responses to spring drought and the pulse effect of rainfall following summer drought. Our study highlights the contrasting responses of Ra and Rh to seasonal drought. Spring drought significantly reduced the relative contribution of Rh to Rs, but summer drought increased the relative contribution of Rh to Rs. These results suggest that future increases in the frequency of summer droughts may accelerate the turnover of soil C and further affect the stability of soil C stocks in semi-arid regions.

Subarctic winter warming promotes soil microbial resilience to freeze-thaw cycles and enhances the microbial carbon use efficiency.

Climate change is predicted to cause milder winters and thus exacerbate soil freeze-thaw perturbations in the subarctic, recasting the environmental challenges that soil microorganisms need to endure. Historical exposure to environmental stressors can facilitate the microbial resilience to new cycles of that same stress. However, whether and how such microbial memory or stress legacy can modulate microbial responses to cycles of frost remains untested. Here, we conducted an insitu field experiment in a subarctic birch forest, where winter warming resulted in a substantial increase in the number and intensity of freeze-thaw events. After one season of winter warming, which raised mean surface and soil (-8 cm) temperatures by 2.9 and 1.4°C, respectively, we investigated whether the insitu warming-induced increase in frost cycles improved soil microbial resilience to an experimental freeze-thaw perturbation. We found that the resilience of microbial growth was enhanced in the winter warmed soil, which was associated with community differences across treatments. We also found that winter warming enhanced the resilience of bacteria more than fungi. In contrast, the respiration response to freeze-thaw was not affected by a legacy of winter warming. This translated into an enhanced microbial carbon-use efficiency in the winter warming treatments, which could promote the stabilization of soil carbon during such perturbations. Together, these findings highlight the importance of climate history in shaping current and future dynamics of soil microbial functioning to perturbations associated with climate change, with important implications for understanding the potential consequences on microbial-mediated biogeochemical cycles.

Temperature responses of leaf respiration in light and darkness are similar and modulated by leaf development.

Our ability to predict temperature responses of leaf respiration in light and darkness (RL and RDk ) is essential to models of global carbon dynamics. While many models rely on constant thermal sensitivity (characterized by Q10 ), uncertainty remains as to whether Q10 of RL and RDk are actually similar. We measured short-term temperature responses of RL and RDk in immature and mature leaves of two evergreen tree species, Castanopsis carlesii and Ormosia henry in an open field. RL was estimated by the Kok method, the Yin method and a newly developed Kok-iterCc method. When estimated by the Yin and Kok-iterCc methods, RL and RDk had similar Q10 (c. 2.5). The Kok method overestimated both Q10 and the light inhibition of respiration. RL /RDk was not affected by leaf temperature. Acclimation of respiration in summer was associated with a decline in basal respiration but not in Q10 in both species, which was related to changes in leaf nitrogen content between seasons. Q10 of RL and RDk in mature leaves were 40% higher than in immature leaves. Our results suggest similar Q10 values can be used to model RL and RDk while leaf development-associated changes in Q10 require special consideration in future respiration models.

Extreme precipitation causes divergent responses of root respiration to nitrogen enrichment in an alpine meadow

Grassland roots are fundamental to obtain the most limiting soil water and nitrogen (N) resources. However, this natural pattern could be significantly changed by recent co-occurrence of N deposition and extreme precipitations, likely with complex interactions on grassland root production and respiration. Despite this nonlinearity, we still know little about how extreme precipitation change nonlinearly regulates the responses of root respiration to N enrichment. Here, we conducted a 6-year experiment of N addition in an alpine meadow, coincidently experiencing extreme precipitations among experimental years. Our results demonstrated that root respiration showed divergent responses to N addition along with extreme precipitation changes among years. Under normal rainfall year, root respiration was significantly stimulated by N addition, whereas it was depressed under high or low water. Moreover, we revealed that both root biomass and traits (i.e. specific root length) were critical mechanisms in affecting root respiration response, but their relative importance changed with water condition. For example, specific root length and specific root respiration were more dominant than root biomass in determining root respiration response under low water, or vice versa. Overall, this study comprehensively reveals the nonlinearity of root respiration responses to the interactions of N enrichment and extreme water change. These new findings help to reconcile previously conflicting results that obtain in a specific episode of water gradient, with important implications for understanding grassland belowground carbon dynamics in facing combined N deposition and extreme precipitation events.

Time-dependent regulation of respiration is widespread across plant evolution.

Establishing the temperature dependence of respiration is critical for accurate predictions of the global carbon cycle under climate change. Diurnal temperature fluctuations, or changes in substrate availability, lead to variations in leaf respiration. Additionally, recent studies hint that the thermal sensitivity of respiration could be time-dependent. However, the role for endogenous processes, independent from substrate availability, as drivers of temporal changes in the sensitivity of respiration to temperature across phylogenies has not yet been addressed. Here, we examined the diurnal variation in the response of respiration to temperatures (R-T relationship) for different lycophyte, fern, gymnospermand angiosperm species. We tested whether time-dependent changes in the R-T relationship would impact leaf level respiration modelling. We hypothesized that interactions between endogenous processes, like the circadian clock, and leaf respiration would be independent from changes in substrate availability. Overall, we observed a time-dependent sensitivity in the R-T relationship across phylogenies, independent of temperature, that affected modelling parameters. These results are compatible with circadian gating of respiration, but further studies should analyse the possible involvement of the clock. Our results indicate time-dependent regulation of respiration might be widespread across phylogenies, and that endogenous regulation of respiration is likely affecting leaf-level respiration fluxes.

Estimation of Heterotrophic Soil Respiration Response to the Summer Precipitation Regime and Different Depths of Snow Cover in a Temperate Continental Climate

Regime of precipitation and temperature conditions are key factors that regulate the rate of decomposition of soil organic matter in terrestrial ecosystems. The aim of this work was to assess the effect of the duration of dry periods in summer and different depths of snow cover in winter on heterotrophic soil respiration. The studies were carried out as part of a 2–year field manipulation experiment organized on gray soil (Haplic Luvisol) in the temperate continental climate conditions (southern Moscow region). Three variants were organized: (1) simulation of mild weather with uniform watering of the soil in summer and the absence of freezing in winter, (2) simulating two summer dry periods lasting 1–2 months with natural winter snow cover, (3) simulation of extreme weather with one long (~3 months) dry period in summer and complete removal of snow cover in winter. Heterotrophic soil respiration was measured by the closed chamber method on bare fallow during 2 years of continuous experiment and 1 more year after its completion. Medians of heterotrophic soil respiration for the entire period of the experiment in the three above–mentioned variants of the experiment were 38, 27 and 19 mg C/(m2 h), respectively. Two short dry periods led to an increase in heterotrophic soil respiration by 7–10%, which is associated both with the drying and rewetting cycles of the soil and with an increase in the average summer temperature of a 20–cm soil profile by 1.5°C. The prolonged dry period caused a decrease in heterotrophic soil respiration by 12–16% as a result of low soil moisture. Soil freezing led to a strong decrease in winter CO2 emission from soil, which reached 34–55% in the control variant and 57–72% when the snow cover was removed. The frost period (November–March) contributed from 25–34% without of soil freezing to 14–19% when its presence to the annual CO2 flux. We conclude that the change in the winter temperature regime of the soil due to manipulations with the snow depth led to a more significant change in the annual heterotrophic soil respiration than the lack of precipitations in the summer season.

Response of Soil Respiration to Altered Snow Cover in a Typical Temperate Grassland in China

The snow cover in temperate areas is undergoing significant changes, which may affect soil respiration (Rs), the second largest carbon flux in global carbon cycling. However, currently, there are relatively few in situ field studies on the effects of altered snow cover on Rs in temperate areas during the non-growing season compared to the research on Rs during the growing season. Therefore, it limited the accurate prediction of the characteristics and magnitude of changes in soil carbon emissions in temperate areas under global change scenarios. Here, an in situ field experiment was conducted in a typical grassland in Inner Mongolia in China to explore the characteristics of Rs under three different snow cover treatments, i.e., increasing snow (IS), decreasing snow (DS), and ambient snow that was regarded as the control check treatment (CK). The results showed that the range of Rs flux and cumulative emission flux in all treatments in the non-growing season in the study area ranged from 5.87 ± 0.20 to 55.11 ± 6.42 mg CO2 m−2 h−1 and from 22.81 ± 0.68 to 26.36 ± 0.41 g C m−2, respectively. During the observation period, the depth of the largest snow cover for each treatment did not exceed 18 cm, and none of the snow treatments caused significant variations in Rs flux (p > 0.05). However, the cumulative flux of Rs in the whole non-growing season was only stimulated significantly by 15.6% by the IS treatment compared with that of CK. The relatively high Rs flux in the non-growing season was observed to mainly occur in the soil deeply frozen period (DFP) and the soil melting period (SMP). Further analysis revealed that Rs flux under different snow treatments were mainly positively correlated with soil temperature during SMP. The main factors controlling Rs varied with different sampling periods. Our findings suggest that the non-growing season is also an important period of non-negligible carbon emissions from typical grassland soils in temperate zones.

Application Nanobiotech in Neurodegenerative Diseases

Background: An early pathogenic role for mitochondrial dysfunction in affected neurons, which occurs before morphological and functional abnormalities, is being supported by expanding information from studies on neurodegenerative diseases. Age is the primary risk factor for numerous diseases that affect people, the degenerative disorders are characterized by an abnormal protein accumulation, progressive loss of neuron cells, and impaired motor or cognitive abilities. One of the fundamental characteristics of aging is mitochondrial malfunction, especially in organs that need a lot of energy, such the heart, muscles, brain, or liver. Small amounts of ROS are produced by natural cell functions such aerobic respiration and inflammatory response mostly in macrophages and hepatocytes.

Catathrenia in severe obstructive sleep apnea: A novel entity never described before

Study objectivesCatathrenia, derived from the Greek κατά (kata) meaning below and θρηνώ (threnia) to lament, is characterized by expiratory groaning episodes during sleep. In a case series of nine patients with severe obstructive sleep apnea, we observed a peculiar groaning entity that has not been described before. MethodsWe described and illustrated the cases with polysomnographic tracings and additional audio recordings. ResultsAll patients were men, obese (body mass index 39 ± 6 kg/m2) with an apnea-hypopnea index ranging from 47 to 125/h. In addition, we identified groaning events that were consistently preceded by a cortical arousal associated with a “rescue” respiration after an obstructive hypopnea or apnea. These events exhibited characteristics of “mixed apnea’s”, but the “central apnea-like part” was a prolonged expiratory groaning phase, with immediately after the terminal expiratory snort appearance of an obstructive apnea. In case the duration of this expiration was at least 10 s we calculated these events separately and the index was 8.4 ± 7.7/h. More rarely (index 0.6 ± 0.5/h) a “central apnea mimicking event” with groaning not followed by an obstruction, was observed. We also observed groaning episodes during expiration with a shorter duration (less than 10 s), not calculated separately. Positive airway pressure, which was well tolerated, eliminated these events. ConclusionsThis novel catathrenia entity preceded by a cortical arousal and “rescue” respiration in response to obstructive events is intriguing. Possible explanations for these observations are further discussed in this article.

Community composition and physiological plasticity control microbial carbon storage across natural and experimental soil fertility gradients

Many microorganisms synthesise carbon (C)-rich compounds under resource deprivation. Such compounds likely serve as intracellular C-storage pools that sustain the activities of microorganisms growing on stoichiometrically imbalanced substrates, making them potentially vital to the function of ecosystems on infertile soils. We examined the dynamics and drivers of three putative C-storage compounds (neutral lipid fatty acids [NLFAs], polyhydroxybutyrate [PHB], and trehalose) across a natural gradient of soil fertility in eastern Australia. Together, NLFAs, PHB, and trehalose corresponded to 8.5–40% of microbial C and 0.06–0.6% of soil organic C. When scaled to “structural” microbial biomass (indexed by polar lipid fatty acids; PLFAs), NLFA and PHB allocation was 2–3-times greater in infertile soils derived from ironstone and sandstone than in comparatively fertile basalt- and shale-derived soils. PHB allocation was positively correlated with belowground biological phosphorus (P)-demand, while NLFA allocation was positively correlated with fungal PLFA : bacterial PLFA ratios. A complementary incubation revealed positive responses of respiration, storage, and fungal PLFAs to glucose, while bacterial PLFAs responded positively to PO43-. By comparing these results to a model of microbial C-allocation, we reason that NLFA primarily served the “reserve” storage mode for C-limited taxa (i.e., fungi), while the variable portion of PHB likely served as “surplus” C-storage for P-limited bacteria. Thus, our findings reveal a convergence of community-level processes (i.e., changes in taxonomic composition that underpin reserve-mode storage dynamics) and intracellular mechanisms (e.g., physiological plasticity of surplus-mode storage) that drives strong, predictable community-level microbial C-storage dynamics across gradients of soil fertility and substrate stoichiometry.

Seasonal patterns of carbon and water flux responses to precipitation and solar radiation variability in a subtropical evergreen forest, South China

Precipitation and energy are vital factors profoundly affecting carbon and water fluxes in subtropical forest ecosystems. However, knowledge of the seasonality of ecosystem productivity and water fluxes and their dominant controlling factors remains understudied. Based on 12 years (2003–2014) of eddy-covariance measurements, we examined how the seasonal carbon flux components and evapotranspiration respond to climatic variability in a subtropical forest ecosystem. Our results showed that both the magnitude and the percentage of gross ecosystem productivity (GEP) and ecosystem respiration (Reco) in winter increased. The enhanced GEP during winter and dampened Reco in summer and autumn were not sufficient to compensate for the decreased GEP in spring, summer and autumn, and simultaneously increased Reco in spring and winter. Thus, net ecosystem productivity (NEP) slightly diminished during the study period, and the majority of annual net carbon gains occurred in winter and spring with high water use efficiency. In addition, solar radiation predominantly contributed to GEP in spring and winter, while soil moisture is the main contributor in summer. ET greatly determined the GEP in autumn due to both were well-coupled. The vapor pressure deficit (VPD) was a major driver of Reco in summer and autumn inferred that Reco largely depends on substrate availability. However, Reco was mainly attributed to the soil environmental conditions (moisture and temperature) in spring and winter. Our results highlighted that the different extents and asynchronous responses of ecosystem carbon assimilation and respiration to altered energy and moisture availability determined the seasonal patterns of carbon and water fluxes, thus having important implications for assessing or projecting subtropical forest ecosystem responses to current climate change.

Cuproptosis as the new kryptonite of cancer: a copper-dependent novel cell death mechanism with promising implications for the treatment of hepatocellular carcinoma.

Copper is an essential element for critical cellular functions such as mitochondrial respiration, cholesterol biosynthesis and immune response. Altered copper homeostasis has been associated with various disorders, including cancer. The copper overload is known to contribute to tumorigenesis, angiogenesis and metastasis, and recently it has been suggested that the elevated level of this element may also create vulnerability to a novel cell death mechanism, named cuproptosis. Excessive amount of copper in mitochondria binds to lipoylated enzymes of the TCA cycle and forms insoluble oligomers. The aggregation of these oligomers and subsequent iron-sulfur cluster protein loss results in proteotoxic stress and eventual cell death. Hepatocellular carcinoma is a common malignancy with a low survival rate, despite the available treatment options. The discovery of cuproptosis led many researchers to explore its potential use in hepatocellular cancer therapy due to the rich mitochondria content of hepatic cells. In this regard, a number of genomic studies were conducted to discover several cuproptosis-related genes and explored their association with prognosis, survival and immunotherapy response. This review brings together the available data on the relationship between cuproptosis and hepatocellular cancer for the first time, and highlights some of the potential biomarkers or target molecules that may be useful in the treatment.

Response of soil respiration and carbon budget to irrigation quantity/quality and biochar addition in a mulched maize field under drip irrigation.

Biochar addition strongly alters net carbon (C) balance in agroecosystems. However, the effects of biochar addition on net C balance of maize field under various irrigation water quantities and qualities remains unclear. Thus, a field experiment combining two irrigation levels of full (W1) and deficit irrigation (W2 = 1/2 W1), two water salinity levels of fresh (S0, 0.71 g L-1 ) and brackish water (S1, 4 g L-1 ), and two biochar addition rates of 0 t ha-1 (B0) and 60 t ha-1 (B1) was conducted to investigate soil carbon dioxide (CO2 ) emissions, maize C sequestration and C budget. Compared with W1, W2 reduced average cumulative CO2 emissions by 6.5% and 19.9% for 2020 and 2021, respectively. The average cumulative CO2 emissions under W1S1 treatments were 5.4% and 22.3% lower than W1S0 for 2020 and 2021, respectively, whereas W2S0 and W2S1 had similar cumulative CO2 emissions in both years. Biochar addition significantly increased cumulative CO2 emissions by 17.8-23.5% for all water and salt treatments in 2020, and reduced average cumulative CO2 emissions by 11.9% for W1 but enhanced it by 8.0% for W2 in 2021. Except for W2S1, biochar addition effectively increased total maize C sequestration by 6.9-14.8% for the other three treatments through ameliorating water and salt stress over the 2 years. Compared with W1S0, W1S1 did not affect net C sequestration, but W2 treatments significantly decreased it. Biochar addition increased net C sequestration by 39.47-43.65 t C ha-1 for four water and salt treatments for the 2 years. These findings demonstrate that biochar addition is an effective strategy to increase both crop C sequestration and soil C storage under suitable water-saving irrigation methods in arid regions with limited freshwater resources. © 2023 Society of Chemical Industry.

The temporal response of soil respiration to environment differed from that on spatial scale

In the context of increasing CO2 concentrations and climate warming, there are large uncertainties regarding the regulatory mechanisms of soil respiration and its accurate assessment. As an area sensitive to global climate change, China covers a broad range of longitudes, latitudes, and altitudes, and it is of great significance to study the spatial and temporal patterns of soil respiration and its environmental response in China's terrestrial ecosystems to clarify the mechanisms of regional and global carbon balance processes. Based on the expanded annual soil respiration dataset from 1993 to 2020, we evaluated soil respiration in China's terrestrial ecosystems and its responses to environmental factors. The mean annual soil respiration in China's terrestrial ecosystems was 777.90 ± 489.43 g C m−2 yr−1 by arithmetic averaging and 595.52 g C m−2 yr−1 by area weighting, with soil respiration in wetlands being higher than that of the forest, grassland, shrubland, cropland, and desert. Soil respiration showed a significant upward trend from 2000 to 2017, which was mainly caused by a significant increase in soil respiration in grasslands due to increasing precipitation. In addition, we found differences in the environmental factors influencing the interannual and spatial variability of soil respiration. The response sensitivities of soil respiration to environmental changes differed significantly among the various ecosystem types; however, these differences were not significant when comparing interannual and spatial scales. This study provides information on soil respiration in China's terrestrial ecosystem and highlights the importance of considering the two-dimensional responses of soil respiration to environmental changes in both time and space.

Effect of straw return on soil respiration in dryland agroecosystem of China: A meta-analysis

In agroecosystems, straw return is considered an important agricultural management practice influencing soil respiration. However, the impact of straw return on soil respiration is equivocal and the underlying mechanisms underpinning any responses remain unclear. To address this, we synthesized 86 recently published papers on dryland agroecosystems in China, which comprise approximately 74% of the agricultural land area, using a meta-analysis approach and explored the influence of straw return on soil respiration and the underlying mechanisms involved. Straw return resulted in a 13.5% increase in soil respiration, a 9.4% increase in soil moisture, a 10.4% increase in crop yield, a 18.9% increase in SOC (soil organic carbon), and a 2.6% decrease in soil temperature. Compared to conventional tillage without straw return treatment, the increase in soil respiration in response to straw return was closely related to modifications in soil temperature, soil moisture, SOC, and crop yield (P < 0.05). The contribution of the different drivers to increases in soil respiration in response to straw return showed a trend of crop yield > soil temperature > SOC > soil moisture. In addition, straw mulching, crop planting system, tillage method, and fertilization modified the effect of straw return on soil respiration. The increase in soil respiration was less when straw was used as a mulch (12.9%), compared to when it was incorporated into the soil (18.8%). The cropping system also influenced the effect of straw return on soil respiration and was increased by 21.1% in inter-crops, and by 17.3% and 11.0% in monocultures and rotations treatments, respectively. Our results also showed that the effect of straw return on soil respiration was larger in deep tillage treatments than in shallow tillage treatments (26.9% vs.18.7%). In addition, the effect of straw return on soil respiration was also larger in fertilized treatment compared to unfertilized one (12.7% vs. 0.5%). However, this depended on the amount of nitrogen fertilizer applied rates and was higher (14.8%) with low (<300 kg ha−1) application rates compared to high (≧300 kg ha−1) ones (2.5%). Therefore, in dryland agroecosystems in China, biological factors, especially those related to crop yield, may be a more important factor regulating the effect of straw return on soil respiration. However, straw mulching, crop planting system, tillage method, and fertilization can modify the effect of straw return on soil respiration.

Soil aggregate-associated organic carbon mineralization and its driving factors in rhizosphere soil

Understanding the determinants of soil carbon mineralization at both the aggregate and rhizosphere levels is crucial for providing precise feedback on climate change. However, the specific patterns and relative contributions of rhizosphere effects on carbon mineralization at the aggregate scale remain unclear. To address this, we conducted an incubation experiment to examine the impact of warming on soil carbon mineralization. We also assessed variations in microbial activities and soil properties across different aggregates in both rhizosphere and non-rhizosphere soils, while exploring how the rhizosphere effects modulated the response of soil respiration to warming. Our findings revealed that rhizosphere soil provides a favorable environment for microbial activities through increased nutrient input and aggregate stability, leading to significant increases in microbial biomass and enzyme activity, thus promoting soil carbon mineralization. Moreover, the spatial heterogeneity of soil aggregates contributes to the differentiation and diversity of microbial community distribution, which further enhances the diversification of carbon mineralization at the aggregate level. Notably, macroaggregates play a significant role in soil carbon flux, making a substantial contribution to carbon turnover in the ecosystem. The partial least squares (PLS) path analysis indicated that the rhizosphere positively increased the contributions of soil properties and microbial variables to the overall amount of soil cumulative mineralization, with soil nutrients playing a crucial role among these factors. These findings highlight the complex regulatory role of substrate quality in soil carbon mineralization dynamics at the aggregate scale, underscoring its far-reaching implications for accurately predicting the feedback to climate change in soil carbon mineralization.

Mechanistic constraints on the trade-off between photosynthesis and respiration in response to warming.

Phytoplankton are responsible for half of all oxygen production and drive the ocean carbon cycle. Metabolic theory predicts that increasing global temperatures will cause phytoplankton to become more heterotrophic and smaller. Here, we uncover the metabolic trade-offs between cellular space, energy, and stress management driving phytoplankton thermal acclimation and how these might be overcome through evolutionary adaptation. We show that the observed relationships between traits such as chlorophyll, lipid content, C:N, and size can be predicted on the basis of the metabolic demands of the cell, the thermal dependency of transporters, and changes in membrane lipids. We suggest that many of the observed relationships are not fixed physiological constraints but rather can be altered through adaptation. For example, the evolution of lipid metabolism can favor larger cells with higher lipid content to mitigate oxidative stress. These results have implications for rates of carbon sequestration and export in a warmer ocean.

Soil respiration responses of moss and lichen biocoenoses to moderate and severe rain events after summer drought in a temperate early‐successional ecosystem

AbstractIt is commonly accepted that CO2 efflux increases with soil water content in aerated soils and that rewetting after periods of soil drying can result in respiration pulses. It has further been shown that soil pores may become water logged which can impede soil gas exchange. The present study aimed to quantify the carbon response of moss (Polytrichum piliferum) and lichen (Cladonia coniocraea) biocoenoses to different quantities of rain in an artificial catchment, which granted that the starting point of the development of both biocoenoses was the same. To address this aim, we conducted in situ soil moisture and soil respiration measurements, where soil respiration was hypothesised to emerge from a cryptogamic vegetation layer and from mineral soil beneath. We found that higher water‐holding capacity of the moss layer and higher accumulation of organic matter in the upper mineral soil under mosses result in higher amounts of water stored near the surface. As a consequence, evaporation of water as well as pulses of CO2 efflux after moderate rain following a period of drought were higher in the moss biocoenosis, where the upper mineral soil was of key importance. In contrast, the lichen biocoenosis facilitated penetration of rainwater into the deep soil. Superimposing rewetting pulses, near‐saturation of soil pores with water after severe rain resulted in gas exchange inhibition and diminished soil respiration until subsequent aeration in both biocoenoses.

Soil respiration and carbon stock responses to land use changes in the temperate forest of northern Iran

Soil respiration and carbon stock responses to land use changes in the temperate forest of northern Iran

The response of soil respiration to land‐use change depends on soil microbial community being regulated by edaphic factors in the Loess Plateau, China

AbstractLand‐use change has significant influences on soil respiration (Rs) in terrestrial ecosystems. Soil microbes play critical roles in soil carbon cycling. Nevertheless, the specific mechanism of how changes in soil microbial properties are linked to the variation of Rs rate during land‐use change still remains poorly understood, especially in the Loess Plateau, China. Here, the characteristics of Rs rate and soil microbial community following the land‐use change from farmland to plantation/grassland were analyzed via an automated soil CO2 flux system and high‐throughput 16S rDNA gene sequencing. The afforestation altered soil microbial diversity and community composition, which was mainly explained by soil pH, temperature, organic matter, nitrate, alkali‐hydrolyzed nitrogen, and available phosphorus. The biomarkers of Bacteroidetes, Firmicutes, and Thaumarchaeota were found in farmland soil at the phylum level. The afforestation also significantly decreased Rs rate, which was closely related to Shannon's index, Simpson's index, and some microbial taxa, such as Bacteroidetes, Firmicutes, Nitrospirae, and Acidobacteria. Bacteroidetes, and Firmicutes were particularly expected to be important drivers of high Rs rate in farmland soil. Moreover, the microbial interaction was probably also an important factor affecting Rs rate. Our results indicate that the response of Rs to land‐use change depends on soil microbial community being regulated by soil physicochemical properties in the Loess Plateau, China.