首页期刊导航|Soil Biology & Biochemistry
期刊信息/Journal information
Soil Biology & Biochemistry
Pergamon Press.
Soil Biology & Biochemistry

Pergamon Press.

0038-0717

Soil Biology & Biochemistry/Journal Soil Biology & BiochemistrySCIISTPAHCI
正式出版
收录年代

    The impact of drought length and intensity on N cycling gene abundance, transcription and the size of an N2O hot moment from a temperate grassland soil

    Barrat H.A.Cardenas L.Clark I.M.Evans J....
    10页
    查看更多>>摘要：? 2022This study aimed to investigate the relationship between drought length, drought intensity and the size of the N2O hot moment. It selected two treatments to deduce the main nitrogen cycling process producing N2O (increasing WFPS from 40% to 90%, and from 70% to 90%), by destructively sampling soil cores to analyse gene abundance, transcription, and changes in soil chemistry (TON, NH4+, DOC). Five other drought and rewetting treatments on packed soil cores were selected to create the drought curves described in Barrat et al. (2020): these included increases of WFPS from 40% to 90%, 50%–90%, 60%–90%, 70%–90%, and 30%–60%. For each treatment, drought lengths were imposed from 0 to 30 days. A quadratic linear regression was fitted to the cumulative emissions data. This model explained a significant proportion of the total variation in the data (R2 = 0.72, p ≤ 0.001). All treatments had an increase in daily N2O emissions post wetting typical of a hot moment apart from the 30%–60% WFPS treatment. In terms of drought intensity, the 40%–90% WFPS was significantly larger than rest, probably due to a relatively larger change in water potential compared to the other treatments. The response to drought length followed a quadratic curve with a downward linear trend, with the largest emissions observed between 10 and 15 days of drought, and the smallest at 0 and 30 days. We suggest a 2-stage dormancy strategy to explain this, where microbes under dry conditions store osmolytes which are catabolised upon rewetting, however at prolonged negative water potentials this strategy is no longer effective, and so they enter a deeper state of dormancy where they can no longer rapidly respond to the changing water potential. Given the delayed response after rewetting, and the inverted U shaped curve in terms of drought length, it seems likely that the majority of emissions are of biological origin. The soil's chemistry data suggested that NH4+ was a key factor controlling the emission flux, but the transcriptional and genomic data were inconclusive. This study therefore suggests that future experiments should focus changes in osmolyte accumulation and catabolism as the key explanation for N2O hot moments, rather than changes in genomic and transcriptomic data or soil substrates, which do not always correlate with emissions.
      原文链接:
    • NSTL
    • Elsevier

    Response of grassland soil respiration to experimental warming: The long-term effects may be greater than we thought

    Chen Z.Zhao D.Zhu Y.Zhang R....
    9页
    查看更多>>摘要：? 2022 Elsevier LtdSoil respiration (Rs) profoundly affects the global carbon cycle, and its response to climate warming in grasslands shows significant heterogeneity for poorly understood reasons. A meta-analysis was undertaken to evaluate the effects of warming (including the magnitude, methods, and duration of warming) and environmental factors (including climate, soils, and plants) on the response of Rs to warming in grasslands, using a global dataset of 168 independent measurements. Multi-model inference, an information-theoretical method for synthesizing results of multiple alternative models, was used to quantify the relative importance of the environmental factors. We found that the response of Rs to warming followed a three-phase pattern: Rs increased initially, then remained unchanged, and then increased again as the duration of warming increased. The long-term response was greater than the short-term response. The Rs response was also affected by the method of warming, with open-top chambers promoting Rs more than infrared heaters. The response of Rs to warming was also positively related to the magnitude of warming. Rs was greatly increased with warming in temperate grasslands compared with that in cold grasslands but did not change significantly in arid grasslands. According to multi-model inference, this can be attributable to differences in soil nutrients and the mean annual precipitation. Our findings suggest a greater long-term stimulation of Rs in a warming world than we previously thought, so short-term studies cannot provide a reliable scientific basis for carbon projections under long-term climate warming. Our results also demonstrate that the carbon released in cold grasslands could be overestimated if the water deficiency was not considered.
      原文链接:
    • NSTL
    • Elsevier

    Litter diversity accelerates labile carbon but slows recalcitrant carbon decomposition

    Wang L.Zhou Y.Xu Z.Zhang J....
    6页
    查看更多>>摘要：? 2022 Elsevier LtdIn biodiverse ecosystems, leaf litter of different plant species decomposes in mixtures, for which decomposition rates notoriously deviate from that expected from monospecific treatments. Despite important research efforts in past decades, these litter diversity effects remain difficult to predict. We hypothesized that this is due to a focus on bulk litter decomposition, while different carbon fractions constituting the litter may respond differently to litter diversity, thereby blurring the overall response. To test this hypothesis, we determined how the decomposition of (i) soluble compounds, (ii) cellulose, and (iii) lignin responded to litter mixing in a 3.5-year field experiment in an alpine forest. We found that the decomposition of soluble compounds and cellulose in mixtures was faster than expected from monospecific treatments, while that of lignin was slower. These deviations from expected decomposition rates of each litter carbon fraction were driven by different aspects of the litter functional diversity. This suggests that different mechanisms operating on distinct litter fractions lead to synergistic and antagonistic interactions that simultaneously affect bulk litter decomposition. Furthermore, the magnitude of these fraction-specific deviations from expected decomposition rates consistently decreased throughout decomposition. Considering the response of litter fractions and their temporality, rather than focusing on bulk litter thus seems critical to evaluate the response of decomposition to plant diversity and identify underlying mechanisms.
      原文链接:
    • NSTL
    • Elsevier

    Predominant climate control on green leaf decomposition across subtropical rain and dry forests following hurricane disturbances

    Huang W.Zou X.Gonzalez G.Barberena-Arias M.F....
    11页
    查看更多>>摘要：? 2022 Elsevier LtdHurricanes defoliate canopy and break tree branches and stems, generating large amount of plant debris in forest ecosystems. Forest recovery after hurricane disturbances relies heavily on the decomposition of these plant debris. Here we addressed the “tropical hierarchy of factors” hypothesis that substrate quality replaces climate as the predominant control on plant litter decomposition in tropical forests. We compared leaf decomposition between subtropical rain and dry forests on the island of Puerto Rico by reciprocally transplanting green-leaf litter between rain (Eugenia borinquensis leaves with higher C/N) and dry (Bucida buceras leaves with lower C/N) forests following hurricanes Irma and Maria. We show that leaf decomposed substantially faster in subtropical rain than dry forests, and for high-than low-quality substrates. Over a period of 536 days of field incubation, loss of leaf ash-free dry mass was 51.8% for B. buceras and 26.6% for E. borinquensis in the rainforest, 15.7% for B. buceras and near zero for E. borinquensis in the dry forest. We also found that soil arthropod density was more than 10-folds greater in the rainforest than in the dry forest and was only more than 2-folds greater in the low C/N litterbags than the high C/N litterbags. Analyses of structural equation model revealed that leaf decomposition rate correlated positively with total arthropod abundance in the rainforest and only with Oribatida abundance in the dry forest. The number of effective linkages among leaf C/N, precipitation and arthropods was greater in the subtropical rainforest (19) than in the dry forest (4), but did not vary between B. buceras (12) and E. borinquensis (11) substrates in the rainforest. We conclude that climate, rather than substrate quality, remains to be the predominant control on leaf decomposition across subtropical rain and dry forests following hurricane disturbances, and the controls of substrate quality on leaf decomposition is inferior and climate dependent.
      原文链接:
    • NSTL
    • Elsevier

    Mechanisms for retention of low molecular weight organic carbon varies with soil depth at a coastal prairie ecosystem

    McFarland J.W.Creamer C.Schulz M.S.Waldrop M.P....
    14页
    查看更多>>摘要：? 2022 Elsevier LtdThough primary sources of carbon (C) to soil are plant inputs (e.g., rhizodeposits), the role of microorganisms as mediators of soil organic carbon (SOC) retention is increasingly recognized. Yet, insufficient knowledge of sub-soil processes complicates attempts to describe microbial-driven C cycling at depth as most studies of microbial-mineral-C interactions focus on surface horizons. We leveraged a well-studied paleo-marine terrace (90 ka) located near Santa Cruz, CA, to characterize the short-term (days to weeks) and intermediate-term (months to years) fate of two low molecular weight organic carbon. compounds at three depths in the soil profile (～25 cm, A horizon; ～75 cm A/B transition; and ～125 cm, B horizon). We employed isotopically-labeled glucose (GLU) and oxalic acid (OXA) to represent two common classes of rhizodeposits: carbohydrates and organic acids. Using a combination of laboratory (9 d) and field (490 d) incubations, we traced the fate of GLU-C and OXA-C through dissolved-, metal-associated-, and microbially-respired CO2 and bulk SOC pools. Our results suggest new SOC retention (i.e., defined as 13C label identified in solid or aqueous fractions) over intermediate time frames (490 d) is correlated with patterns in short-term (9 d) cycling dynamics, which in turn is related to the theoretical efficiency by which microorganisms process each substrate. For all horizons (A, A/B, and B) GLU-C was converted to CO2 more quickly than OXA-C with modeled decomposition rates ～2–4 times faster for GLU depending on microbial density (higher in A than B horizon). The faster decomposition rates of GLU-C increased fractional recovery (0.399 ± 0.026 to 0.504 ± 0.030 for GLU-C) compared to OXA-C (0.035 ± 0.003 to 0.127 ± 0.010) among all horizons in our field experiment (490 d). Though the overall proportion of GLU-C recovered in solid fractions did not vary significantly with horizon, based on 13C recovered in aqueous fractions the apparent mechanism for retention did. After the 9-d laboratory incubation, fractional recovery for GLU-C among C pools associated with microbial biomass was almost 20× higher than OXA-C (0.192 versus 0.010, respectively across all horizons). More than a year later, 43–46% of GLU-C retained in the field incubation was extractable with a neutral salt (representing a pool of soil C residing within or available to microbial biomass) among A and A/B horizons, while only 6% of retained GLU-C was similarly extractable in the B horizon. Thus, it appears among depths with higher microbial density (A, A/B horizons), anabolic recycling is the most likely process contributing to the persistence of glucose C, whereas abiotic sinks contributed more to intermediate-term stability for GLU-C in the B horizon. By contrast, most OXA-C was lost, presumably as CO2, over the short-term from the A and A/B horizons (fractional recovery: 0.136 ± 0.011 and 0.091 ± 0.002, respectively). However, though substantially lower than GLU-C recovered at the conclusion of our field experiment, the fraction of oxalic acid C retained in the B horizon over both short- (0.72 ± 0.037) and intermediate-time (0.127 ± 0.010) frames was several-fold higher than for overlying horizons. The specific process(es) (e.g., more efficient microbial utilization, metal-organic complexation, direct adsorption to the mineral matrix, etc.) contributing to higher retention for OXA-C at depth are discussed but remain unresolved.
      原文链接:
    • NSTL
    • Elsevier

    Oxygen gas derived oxygen does not affect the accuracy of 18O-labelled water approach for microbial carbon use efficiency

    Wang Z.Yang J.Bai E.Wang C....
    3页
    查看更多>>摘要：? 2022 Elsevier LtdThe 18O-labelled-water incubation approach is the latest widely used method for soil microbial carbon use efficiency (CUE) estimation. This approach assumes oxygen used for microbial DNA synthesis is from growth medium water. However, whether the oxygen might be from oxygen gas (O2) is unknown. Here we compared the results of 18O-labelled water and 18O-labelled O2 incubation experiments following the standard procedure of soil microbial CUE measurement. Results indicated that 99.25% of the oxygen atoms in the newly synthesized microbial DNA after 48 h of incubation were derived from applied water, while 0.75% of the oxygen atoms were derived from O2. Our study suggests the contribution of O2 to microbial DNA synthesis is negligible during short-term incubation and the 18O-labelled-water approach is reliable for estimating soil microbial CUE for the tested forest soil.
      原文链接:
    • NSTL
    • Elsevier

    Heterotrophic nitrification – An eternal mystery in the nitrogen cycle

    Martikainen P.J.
    11页
    查看更多>>摘要：? 2022 The AuthorDespite the fact that heterotrophic nitrification was identified more than 100 years ago, the biochemistry of heterotrophic nitrifiers is poorly known and their contribution to nitrification in soil is still speculative. Heterotrophic nitrifiers need organic compounds as their energy source in contrast to the chemolithotrophic nitrifiers. Most of the potential pathways for nitrite/nitrate production by heterotrophs can be considered as secondary metabolism. Only nitrification and simultaneous denitrification by some heterotrophic bacteria is known to have connection to the energy metabolism. Evidently, the nitrification pathways of bacteria and fungi differ. Some heterotrophic bacteria oxidizing ammonia have ammonia monooxygenase (AMO), but there are also heterotrophic bacteria oxidizing ammonia without AMO. The structure of AMO of chemolithotrophic ammonia oxidizers and heterotrophs differs. AMO has not been found in nitrifying fungi. The conditions for heterotrophic nitrification in soil highly differ from those in waste waters where heterotrophic nitrification activity can be high. Heterotrophic nitrification in soil is limited by the low availability of easily decomposable organic substrates. Possible nitrification by heterotrophs in the rhizosphere and endophytic root microbes gaining a good supply of substrates from plants is not known. Fungi are of special interest in heterotrophic nitrification in soil because fungi can evidently nitrify not only easily decomposable substrates but also when decomposing recalcitrant organic compounds (like lignin) which are abundant in soil. Nitrite/nitrate production from easily decomposable nitrogenous organic compounds, such as amino acids, is common among heterotrophic bacteria and fungi. The general conclusion that heterotrophs use solely an “organic pathway” in their nitrification is, however, not valid because also ammonia can be oxidized. Owing to the diverse, poorly known biochemistry of heterotrophic nitrification and methodological difficulties to differentiate heterotrophic and chemolithotrophic nitrification in soil, the role of heterotrophic nitrification in soil nitrogen cycle remains uncertain.
      原文链接:
    • NSTL
    • Elsevier

    Precipitation balances deterministic and stochastic processes of bacterial community assembly in grassland soils

    Yang L.Tian J.He N.Yu G....
    13页
    查看更多>>摘要：? 2022 Elsevier LtdMicrobial biodiversity is crucial for maintaining ecosystem functions. As climate change progresses at both global and regional scales, there is a need to understand microbial community assembly processes and diversity to predict changes in soil function in different regions. However, our knowledge of the mechanisms that shape bacterial β diversity at multiple spatial scales with complex environmental gradients is very limited. To investigate the mechanisms driving bacterial β diversity at regional (across transects) and local (within transect) scales, soil samples were collected from 30 grassland ecosystems in three east-west transects in northern China. The regional species pools influenced β diversity by mediating rare taxa migration across the three transects. After correcting for regional differences in species, the importance of local community assembly processes in controlling bacterial diversity was independent of spatial scales. Homogeneous selection (HoS, 39%–60%) and dispersal limitation (DL, 31%–54%) proved to be the most important community assembly processes for soil bacteria. Two dominant bacterial taxa accounting for 65% of the total abundance were identified, mainly including Acidobacteria, Actinobacteria, and Proteobacteria, with 63% and 64% contributions for the HoS and DL, respectively. Mean annual precipitation (MAP) mediated the relative importance of deterministic and stochastic assembly in bacterial communities. Consistently across all spatial scales, the relative importance of DL increased with aridity, and the contribution of HoS decreased. Importantly, the relative abundance of the two dominant bacterial taxa controlled by the HoS and DL varied with MAP. Collectively, our results provide clear evidence that water availability mediates the community assembly process of soil bacteria. This conclusion is of utmost importance for predicting the dynamics of soil microbial diversity and nutrient cycling in natural ecosystems in drylands.
      原文链接:
    • NSTL
    • Elsevier

    Soil clay minerals: An overlooked mediator of gross N transformations in Regosolic soils of subtropical montane landscapes

    Zhang B.Zhou M.Zhu B.Xiao Q....
    5页
    查看更多>>摘要：? 2022 Elsevier LtdSoil physiochemical and biological properties have been demonstrated as key controllers of nitrogen (N) transformation in soil; however, the roles of different soil properties in regulating the transformation processes and rates of N remain largely uncertain. Therefore, we quantified the gross transformation rate of N in soil and examined its relationships with N transformation-related functional gene abundances, clay minerals, and soil physiochemical properties across seven Regosolic soils within a subtropical montane agricultural landscape using the 15N tracing approach. We detected substantial variations in gross N mineralization, nitrification, and immobilization rates of NH4+ and NO3? across these Regosolic soils; however, across all soils, the immobilization rate of NH4+ was relatively high to NO3? and the soil's capacity to retain NO3? remained very low. The substantial variation in the gross N transformation in soil was primarily attributed to the influences of microbial functional genes (e.g., bacteria amoA for autotrophic nitrification) and soil properties (e.g., soil pH and sand content for organic N mineralization rates). Moreover, the clay mineral content and soil type regulated rates of gross N transformation processes, including autotrophic nitrification, mineralization, and NH4+ immobilization of Regosolic soils in subtropical montane landscapes. These findings suggest that clay minerals should no longer be overlooked as mediators of gross N transformations in soil.
      原文链接:
    • NSTL
    • Elsevier

    The mechanism of the dose effect of straw on soil respiration: Evidence from enzymatic stoichiometry and functional genes

    Li S.Xia Z.Zhang X.Zhu M....
    10页
    查看更多>>摘要：? 2022 Elsevier LtdStraw return to soil is a global field practice for sequestering carbon (C) in agricultural ecosystems, and soil C mineralization depends on the soil microbial metabolic process. However, the variation patterns of microbial respiration (Rs) and associated mechanisms under long-term straw input at different levels remain unclear. Here, this study investigated the changes in Rs and microbial metabolic limitation under straw input at four levels (0, 4, 8, and 12 t ha?1 yr?1) based on a long-term (11-year) field experiment. In addition, the C use efficiency (CUE) and C degradation genes were quantified via an enzyme-based biogeochemical-equilibrium model and high-throughput quantitative PCR-based chip technology, respectively. The results indicated that Rs significantly increased with the amount of straw addition, while its rate of increase dropped when the straw addition amount was greater than 8 t ha?1 yr?1. Interestingly, we also observed an apparent microbial P limitation under straw addition at 0 and 4 t ha?1 yr?1 but a shift to N limitation when the straw addition rate was over 8 t ha?1 yr?1. The shift suggested that Rs changes could be attributed to straw addition leading to soil microbes being increasingly limited by N rather than P. Moreover, straw addition significantly increased microbial biomass, reduced CUE and increased the absolute abundance of genes involved in degrading various organic polymers (e.g., starch, hemicellulose, cellulose, chitin and lignin). Partial least squares path modeling revealed that the variation in Rs was directly attributed to increased microbial biomass and C degradation genes as well as declining CUE, while C degradation genes and CUE were mediated by microbial relative C limitation and N vs. P limitation. This study provides insight into the mechanisms of the Rs response to straw addition by linking the Rs to microbial metabolic limitation, CUE and C degradation genes, highlighting that reducing microbial nutrient limitation by balancing metabolic demand and environmental nutrient supply potentially leads to a higher microbial CUE and lower Rs in agricultural ecosystems.
      原文链接:
    • NSTL
    • Elsevier