Soil Microbial Residues Research Articles

The Fungal Community Structure Regulates Elevational Variations in Soil Organic Carbon Fractions in a Wugong Mountain Meadow.

Soil organic carbon (SOC) fractions are vital intrinsic indicators of SOC stability, and soil fungi are the key drivers of soil carbon cycling. However, variations in SOC fractions along an elevational gradient in mountain meadows and the role of the fungal community in regulating these variations are largely unknown, especially in subtropical areas. In this study, an elevation gradient experiment (with experimental sites at 1500, 1700, and 1900 m) was set up in a Miscanthus sinensis community in a meadow on Wugong Mountain, Southeast China, to clarify the effects of elevation on soil fungal community composition, microbial residue carbon, and SOC fractions. The results showed that the contribution of soil microbial residue carbon to SOC was only 16.1%, and the contribution of soil fungal residue carbon to SOC (15.3%) was far greater than that of bacterial residue carbon (0.3%). An increase in elevation changed the fungal community structure and diversity, especially in the topsoil (0-20 cm depth) compared with that in the subsoil (20-40 cm depth), but did not affect fungal residue carbon in the two soil layers. When separating SOC into the fractions mineral-associated organic carbon (MAOC) and particulate organic carbon (POC), we found that the contribution of MAOC (66.6%) to SOC was significantly higher than that of POC (20.6%). Although an increased elevation did not affect the SOC concentration, it significantly changed the SOC fractions in the topsoil and subsoil. The soil POC concentration and its contribution to SOC increased with an increasing elevation, whereas soil MAOC showed the opposite response. The elevational variations in SOC fractions and the POC/MAOC ratio were co-regulated by the fungal community structure and total nitrogen. Our results suggested that SOC stabilization in mountain meadows decreases with an increasing elevation and is driven by the fungal community structure, providing scientific guidance for SOC sequestration and stability in mountain meadows in subtropical areas.

Canopy and understory nitrogen additions differently affect soil microbial residual carbon in a temperate forest.

Atmospheric nitrogen (N) deposition in forests can affect soil microbial growth and turnover directly through increasing N availability and indirectly through altering plant-derived carbon (C) availability for microbes. This impacts microbial residues (i.e., amino sugars), a major component of soil organic carbon (SOC). Previous studies in forests have so far focused on the impact of understory N addition on microbes and microbial residues, but the effect of N deposition through plant canopy, the major pathway of N deposition in nature, has not been explicitly explored. In this study, we investigated whether and how the quantities (25 and 50 kg N ha-1 year-1) and modes (canopy and understory) of N addition affect soil microbial residues in a temperate broadleaf forest under 10-year N additions. Our results showed that N addition enhanced the concentrations of soil amino sugars and microbial residual C (MRC) but not their relative contributions to SOC, and this effect on amino sugars and MRC was closely related to the quantities and modes of N addition. In the topsoil, high-N addition significantly increased the concentrations of amino sugars and MRC, regardless of the N addition mode. In the subsoil, only canopy N addition positively affected amino sugars and MRC, implying that the indirect pathway via plants plays a more important role. Neither canopy nor understory N addition significantly affected soil microbial biomass (as represented by phospholipid fatty acids), community composition and activity, suggesting that enhanced microbial residues under N deposition likely stem from increased microbial turnover. These findings indicate that understory N addition may underestimate the impact of N deposition on microbial residues and SOC, highlighting that the processes of canopy N uptake and plant-derived C availability to microbes should be taken into consideration when predicting the impact of N deposition on the C sequestration in temperate forests.

Responses of Soil Carbon and Microbial Residues to Degradation in Moso Bamboo Forest.

Moso bamboo (Phyllostachys heterocycla cv. Pubescens) is known for its high capacity to sequester atmospheric carbon (C), which has a unique role to play in the fight against global warming. However, due to rising labor costs and falling bamboo prices, many Moso bamboo forests are shifting to an extensive management model without fertilization, resulting in gradual degradation of Moso bamboo forests. However, many Moso bamboo forests are being degraded due to rising labor costs and declining bamboo timber prices. To delineate the effect of degradation on soil microbial carbon sequestration, we instituted a rigorous analysis of Moso bamboo forests subjected to different degradation durations, namely: continuous management (CK), 5 years of degradation (D-5), and 10 years of degradation (D-10). Our inquiry encompassed soil strata at 0-20 cm and 20-40 cm, scrutinizing alterations in soil organic carbon(SOC), water-soluble carbon(WSOC), microbial carbon(MBC)and microbial residues. We discerned a positive correlation between degradation and augmented levels of SOC, WSOC, and MBC across both strata. Furthermore, degradation escalated concentrations of specific soil amino sugars and microbial residues. Intriguingly, extended degradation diminished the proportional contribution of microbial residuals to SOC, implying a possible decline in microbial activity longitudinally. These findings offer a detailed insight into microbial C processes within degraded bamboo ecosystems.

Soil Microbial Residual Carbon Accumulation Affected by Reclamation Period and Straw Incorporation in Reclaimed Soil from Coal Mining Area

Microbial residual carbon is an important component in soil carbon pool stability. Here, we tested soils collected from the early (first year, R1), middle (10 years, R10), and long-term (30 years, R30) stages of reclamation in a coal mining area in China. Two treatments with straw materials, namely maize straw + soil (S+M) and wheat straw + soil (S+W), were used for a decomposition experiment. The glucosamine and muramic acid contents were assessed. Accumulation of microbial residual C and its contribution to soil organic carbon (SOC) were analyzed at various intervals. Straw incorporation resulted in higher amino sugar accumulation than that of the control. The amino sugar content was considerably higher in R30 than that in R10 and R1; S+M and S+W showed average increases of 15 and 4%, respectively, compared to the control after 500 days. The total microbial and fungal residual C contents under S+M and S+W treatments were substantially higher than those of the control on days 33, 55, and 218 in R30. The contributions of soil microbial residues to SOC at R1, R10, and R30 were 73.77, 71.32, and 69.64%, respectively; fungal residues contributed significantly more than bacterial residues. The total amino sugars and microbial residual C content increased with increasing reclamation period. The addition of maize straw promoted the accumulation of microbial residual C, especially in the early stages of reclamation. Therefore, the addition of maize straw improved the stability of microbial carbon sources in coal mine reclamation soils.

Afforestation with an age-sequence of Mongolian pine plantation promotes soil microbial residue accumulation in the Horqin Sandy Land, China

Afforestation with an age-sequence of Mongolian pine plantation promotes soil microbial residue accumulation in the Horqin Sandy Land, China

Nitrogen deposition caused higher increases in plant-derived organic carbon than microbial-derived organic carbon in forest soils

Plant- and microbial-derived organic carbon, two components of the soil organic carbon (SOC) pool in terrestrial ecosystems, are regulated by increased atmospheric nitrogen (N) deposition. However, the spatial patterns and driving factors of the responses of plant- and microbial-derived SOC to N deposition in forests are not clear, which hinders our understanding of SOC sequestration. In this study, we explored the spatial patterns of plant- and microbial-derived SOC, and their responses to N addition and elucidated their underlying mechanisms in forest soils receiving N addition at four sites with various soil and climate conditions. Plant- and microbial-derived SOC were quantified using lignin phenols and amino sugars, respectively. N addition increased the total microbial residues by 20.5% on average ranging from 9.4% to 34.0% in temperate forests but not in tropical forests, and the increase was mainly derived from fungal residues. Lignin phenols increased more in temperate forests (average of 63.8%) than in tropical forests (average of 15.7%) following N addition. The ratio of total amino sugars to lignin phenols was higher in temperate forests than in tropical forests and decreased with N addition in temperate forests. N addition mainly regulated soil microbial residues by affecting pH, SOC, exchangeable Ca2+, gram-negative bacteria biomass, and the C:N ratio, while it mainly had indirect effects on lignin phenols by altering SOC, soil C:N ratio, and gram-negative bacteria biomass. Overall, our findings suggested that N deposition caused a greater increase in plant-derived SOC than in microbial-derived SOC and that plant-derived SOC would have a more important role in sequestering SOC under increasing N deposition in forest ecosystems, particularly in temperate forests.

Roots have greater effects on the accumulation of soil microbial residue carbon in microaggregate fractions than leaf litter in a subtropical forest

Microbial residues as the key component of the stable soil organic carbon (SOC) play a critical role in stabilizing SOC, and their accumulation is influenced by plant litter. However, how the accumulation of microbial residues in different aggregate fractions of forest soils responds to changes in the inputs of leaf and root litter remains poorly understood. Here, we test the hypothesis that root exclusion has greater effects on microbial residues than leaf-litter exclusion among soil aggregate fractions based on a litter-input manipulation experiment in a subtropical coniferous forest. The concentrations of bacterial, fungal, and total microbial residues were higher in large macroaggregates (> 2000 μm) but lower in small macroaggregates (250–2000 μm). Root exclusion decreased the concentrations of bacterial, fungal, and total microbial residues in microaggregates (< 250 μm), and leaf-litter exclusion decreased fungal residues in microaggregates. Fungal residues had higher proportions to SOC (20.7–34.9%) than bacterial residues (10.8–18.6%) in soil aggregate fractions, and their proportions were higher in large macroaggregates than other aggregate fractions. Root exclusion reduced the higher proportions of bacterial, fungal, and total microbial residues to SOC in microaggregates (14.5%, 15.7%, and 15.3%, respectively), compared to the reduction observed in large macroaggregates (10.8%, 7.1%, and 8.4%, respectively). And leaf-litter exclusion reduced the proportions of fungal and total microbial residues to SOC in microaggregates. Soil microbial residue-carbon accumulation coefficient was higher in large macroaggregates and lower in small macroaggregates. The coefficient was increased by root exclusion in macroaggregates but decreased in microaggregates, and it was also decreased by leaf-litter exclusion in large macroaggregates and microaggregates. Proportions of fungal residues to SOC were more strongly related to the live microbial biomass and nutrients than those of bacterial residues. Our results suggest that root exclusion exerts stronger effects on soil microbial residues than leaf-litter exclusion but these effects vary among soil aggregate sizes.

Interguild fungal competition in litter and soil inversely modulate microbial necromass accumulation during Loess Plateau forest succession

Microbial interactions determine ecosystem carbon (C) and nutrient cycling, yet it remains unclear how interguild fungal interactions modulate microbial residue contribution to soil C pools (SOC) during forest succession. Here, we present a region-wide investigation of the relative dominance of saprophytic versus symbiotic fungi in litter and soil compartments, exploring their linkages to soil microbial residue pools and potential drivers along a chronosequence of secondary Chinese pine (Pinus tabulaeformis) forests on the Loess Plateau. Despite minor changes in C and nitrogen (N) stocks in the litter or soil layers across successional stages, we found significantly lower soil phosphorus (P) stocks, higher ratios of soil C: N, soil N: P and soil C: P but lower ratios of litter C: N and litter C: P in old (>75 years) than young stands (<30 years). Pine stand development altered the saprotroph: symbiotroph ratios of fungal communities to favor the soil symbiotrophs versus the litter saprotrophs. The dominance of saprotrophs in litter is positively related to microbial necromass contribution to SOC, which is negatively related to the dominance of symbiotrophs in soils. Antagonistic interguild fungal competition in litter and soil layers, in conjunction with increased fungal but decreased bacterial necromass contribution to SOC, jointly contribute to unchanged total necromass contribution to SOC with stand development. The saprotroph: symbiotroph ratios in litter and soil layers are mainly driven by soil P stocks and stand parameters (e.g., stand age and slope), respectively, while substrate stoichiometries primarily regulate microbial necromass accumulation and fungal: bacterial necromass ratios. These results provide novel insights into how microbial interactions at local spatial scales modulate temporal changes in SOC pools, with management implications for mitigating regional land degradation.

The Effect of Soil Microbial Residues-Mediated Nitrogen Conservation and Supply during the Growing Season on Nitrogen Uptake by Wheat

Microbial residue nitrogen can indicate soil quality and is crucial for soil nitrogen retention and supply. However, it is still unclear how the dynamic changes in soil microbial residue nitrogen affect crop nitrogen uptake in agricultural practice. Based on a long-term wheat-maize rotation experiment with different nitrogen application rates (150 kg N ha−1, 200 kg N ha−1, and 300 kg N ha−1), 15N-labeled nitrogen fertilizer was applied during the wheat season to track the dynamics of soil microbial residue nitrogen and its mediated fertilizer nitrogen. The results showed that nitrogen addition was beneficial to the accumulation of microbial residue nitrogen (mainly fungal microbial residue nitrogen). Its contribution rate to soil total nitrogen is 54.87–56.55%, and the fertilizer nitrogen allocated to it accounts for 27.10–47.50% of the remaining fertilizer nitrogen in the soil. Ultimately, 6.77–10.24% of the nitrogen fertilizer applied remained in the soil as microbial residue nitrogen. In addition, microbial residue nitrogen is mainly mineralized during the jointing and filling stages of wheat. In a word, the accumulation and mineralization of soil microbial residue nitrogen during the application of 200 kg N ha−1 better guaranteed the uptake of nitrogen by wheat, which provided a reliable basis for guiding farmland fertility improvement and nitrogen fertilizer reduction in the North China Plain.

Influencing mechanism of stand age to the accumulation of microbial residue carbon in the Pinus masso-niana plantations

Clarifying the accumulation pattern of soil microbial residue carbon and its contribution to soil organic carbon (SOC) across stand age is helpful to understand the mechanism underlying soil carbon cycling. In this study, we analyzed the differences of amino sugar content, physicochemical properties and microbial composition in surface soil (0-10 cm) in young (6 a), middle-aged (13 a), near-mature (29 a), mature (38 a) and over-mature (57 a) Pinus massoniana plantations of subtropical China, quantified the microbial residue carbon content and its contribution to SOC, and discussed the mechanism. The results showed that SOC, total nitrogen, amorphous iron oxide and leucine aminopeptidase contents in the middle-aged plantation were significantly lower than those in the mature plantation. Soil pH and fungal/bacteria in young plantation were significantly higher than those in other age groups. Across the stand age gradient, the ranges of microbial, fungal and bacterial residue carbon were 7.52-14.63, 4.03-8.00 and 3.48-6.63 g·kg-1, respectively. The contents of all the residue carbon were significantly higher in the mature plantation than that of the middle-aged plantation, which were positively affected by soil total nitrogen content. The contribution of microbial, fungal, and bacterial residue carbon to SOC was 59.7%-72.3%, 33.4%-45.6%, and 24.3%-30.8%, respectively. The contribution of fungal residue carbon to SOC in young plantation was significantly higher than that in other age groups, and the contribution of bacterial residue carbon to SOC in middle-aged plantation was significantly higher than that in young and near-mature plantations, both of which were affected by soil inorganic nitrogen. Fungal residue carbon content was 1.2-1.7 times as that of bacterial residue carbon content, and dominated for the accumulation of microbial residue carbon. Results of the partial least squares model showed that stand age, soil environmental factors (such as leucine aminopeptidase, amorphous iron oxide, pH, and total nitrogen), bacterial residue carbon, fungal residue carbon and the contribution of bacterial residue carbon to SOC had total effects on the contribution of fungal residue carbon to SOC (-0.37, -1.16, 0.90, 1.09, and 0.83, respectively). In conclusion, stand age promoted the accumulation of microbial residue carbon but did not increase its contribution to SOC.

Soil microbial community structure and soil fertility jointly regulate soil microbial residue carbon during the conversion from subtropical primary forest to plantations

Soil microbes mediate soil organic carbon (SOC) storage by affecting microbial residue carbon (C) in terrestrial ecosystems, a main source of SOC. However, how microbial residue C accumulation changes during the conversion of subtropical primary forest to plantations and the role of soil microbial community structure in regulating these changes remain unclear. Here, effects of conversion from forest on microbial residue C accumulation in three plantations, including tea (Camellia sinensis var. assamica), walnut (Juglans regia), and macadamia (Macadamia integrifolia). We assessed amino sugars content and the relative importance of soil microbial community structure, soil fertility, and aboveground biomass in four forest types in southwest Yunnan province, China. Our results show that total microbial residue C accounted for 27.8 % of SOC on average across all forest types, and fungal residue C contributed more to SOC than bacterial residue C across different forest types. Conversion from primary forest decreased fungal, bacterial, and total microbial residue C content in all plantation types except tea. Microbial residue C contents was significantly lower in the macadamia plantation than in the primary forest and the tea plantation. Fungal and total microbial residue C content increased with increasing soil microbial community composition, soil fungal abundance, and soil fertility. Soil fertility regulated fungal, bacterial, and total microbial residue C accumulation, which was major determinant of microbial residue C via its influence on soil fungal and bacterial abundance. Overall, we found that soil fungal abundance contributed more to microbial residue C accumulation than change in soil microbial community composition. We also found that soil bacterial abundance was negatively correlated with fungal and microbial residue C, while soil fungal abundance was positively related to microbial residue C accumulation. Ascomycota was most important phylum regulating microbial residue C. These findings suggest that soil fungal and bacterial abundance and soil fertility are the principal regulators of microbial residue C accumulation during the conversion from primary forest to different plantations.

Effects of thinning on accumulation of soil microbial residue carbon of Picea asperata plantations in sub-alpine region of western Sichuan, China

Microbial residues are an important component of soil organic carbon (SOC). It is unclear how long-term thinning affects the accumulation characteristics of microbial residue carbon (C). We analyzed the differences in soil physicochemical properties, microbial communities, extracellular enzyme activities, and microbial residue C in topsoil (0-10 cm) and subsoil (20-30 cm) in Picea asperata plantation of non-thinned (control, 4950 trees·hm-2) and thinned for 14 years (1160 trees·hm-2) stands, aiming to reveal the regulatory mechanism of thinning on microbial residue C accumulation. The results showed that thinning significantly increased SOC content, total nitrogen content, available phosphorus content, the proportion of particulate organic C, soil water content, C-cycle hydrolase, and acid phosphatase activities, but significantly reduced the proportion of mineral-associated organic C. Thinning significantly affected the content of fungal and microbial residue C, and the contribution of microbial residue C to SOC, and these effects were independent of soil layer. The content of fungal and microbial residue C was 25.0% and 24.5% higher under thinning treatments. However, thinning significantly decreased the contribution of microbial residue C to SOC by 12.3%, indicating an increase in the proportion of plant-derived C in SOC. Stepwise regression analysis showed that total nitrogen and soil water content were key factors influencing fungal and micro-bial residue C accumulation. In summary, thinning promoted microbial residue C sequestration by altering soil pro-perties and changed the composition of SOC sources.

Accumulation of soil microbial extracellular and cellular residues during forest rewilding: Implications for soil carbon stabilization in older plantations

Soil microbial residues are a critical component of stable soil organic carbon pools in terrestrial ecosystems. Plantations are anticipated to increase soil stable carbon stocks and contribute toward addressing global climate change. How rewilding, as a strategy to restore the multiple ecological functions of plantations, affects soil microbial residues remains to be elucidated. Here, we divided microbial residues into extracellular residues (using extracellular polymeric substances, i.e., EPS, as a proxy) and cellular residues (estimated by amino sugars) and investigated the changes in their accumulation over four decades (6–45 years) of Metasequoia glyptostroboides plantation development. It was found that forest rewilding resulted in a linear accumulation of soil microbial residues and enhanced their contributions to the soil organic carbon. Specifically, EPS-polysaccharide increased by 126.5%, while the total cellular residue carbon, fungal cellular residue carbon, and bacterial cellular residue carbon increased by 73.4%, 77.2%, and 54.3%, respectively. Correspondingly, the contributions of EPS-polysaccharide and total cellular residue carbon to the soil organic carbon increased by 66.1% and 32.1%, respectively. The main drivers behind extracellular and cellular residues differed, with fine root biomass being the main driver of extracellular residues, while soil nitrogen and organic carbon content were the main drivers of cellular residues. Our study demonstrated that through rewilding, microbial extracellular and cellular residues could continuously accumulate in soils and contribute significantly to the sequestration of atmospheric carbon, highlighting the need to incorporate both microbial residues into soil carbon models to address global climate change. The results suggested that plantations should be allowed to grow older rather than being prematurely harvested, as they promote soil carbon sequestration and stabilization, which has important implications for the establishment of stable soil carbon pools in plantations and can be an invaluable asset in the fight against climate change.

Influence of tree species on soil microbial residue accumulation and distribution among soil aggregates in subtropical plantations of China

BackgroundMicrobial residues are significant contributors to stable soil organic carbon (SOC). Soil aggregates effectively protect microbial residues against decomposition; thus, microbial residue accumulation and distribution among soil aggregates determine long-term SOC stability. However, how tree species influence accumulation and distribution of soil microbial residues remains largely unknown, hindering the chances to develop policies for SOC management. Here, we investigated microbial residue accumulation and distribution in soil aggregates under four subtropical tree species (Cunninghamia lanceolata, Pinus massoniana, Michelia macclurei, and Schima superba) after 29 years of afforestation.ResultsAccumulation of microbial residues in the 0–10 cm soil layer was 13.8–26.7% higher under S. superba than that under the other tree species. A structural equation model revealed that tree species affected the accumulation of microbial residues directly by altering fungal biomass. Additionally, tree species significantly affected microbial residue distribution and contribution to SOC in the top 20 cm soil. In particular, microbial residue distribution was 17.2–33.4% lower in large macro-aggregates (LMA) but 60.1–140.7% higher in micro-aggregates (MA) under S. superba than that under the other species in the 0–10 cm soil layer, and 14.3–19.0% lower in LMA but 43–52.1% higher in MA under S. superba than that under C. lanceolata and M. macclurei in the 10–20 cm soil layer. Moreover, the contribution of microbial residues to SOC was 44.4–47.5% higher under S. superba than under the other tree species. These findings suggest a higher stability of microbial residues under S. superba than that under the other studied tree species.ConclusionsOur results demonstrate that tree species influence long-term microbial persistence in forest soils by affecting accumulation and stabilization of microbial residues.

Soil microbial residue characteristics in Pinus massoniana lamb. Plantations

A large amount of stable soil organic matter (SOM) is derived from microbial necromass, which can be assessed by quantifying amino sugar biomarkers. Pinus massoniana Lamb. Plantations are widely distributed in China and play a vital role in forest carbon sequestration. However, the patterns of soil microbial residue remain poorly understood. In this study, amino sugars were used to characterize patterns of soil microbial residues at three soil depths (0–10, 10–20, and 20–30 cm) in P. massoniana plantations of different ages (young, middle-aged, near-mature, mature, and over-mature; denoted as YG, MD, NM, MT, and OM, respectively). In the topsoil (0–10 cm), the total nitrogen (TN) content of the OM forest was the highest, whereas the soil organic carbon (SOC) content of the MT forest was the highest. Consistent with changes in SOC and TN, total microbial residue content decreased with increasing soil depth. However, the total microbial residues C to SOC contribution increased considerably with increasing depth, suggesting that more SOC was derived from microbial residues in the subsoil than that from the topsoil. The fungal residue C to SOC contribution was higher than that of bacterial residue C. Total amino sugar content in the topsoil increased with increasing age, and MT and OM had a significantly higher content than that of other forests. At all soil depths, SOC and TN content predominantly determined microbial necromass, whereas soil microbial biomass content predominantly determined microbial necromass in the topsoil; soil pH predominantly determined microbial necromass in the 10–20 cm soil layer; and soil pH and Ca2+ content were the primary factors in the soil layer below 20 cm. The study provides valuable insights into controls of microbial-derived organic C could be applied in Earth system studies for predicting SOC dynamics in forests.

Effects of no-tillage and different stover mulching amounts on soil microbial community and microbial residue in the Mollisols of China.

To investigate the effects of no-tillage and different amounts of stover mulch on soil microbial community composition and their residues, we set up a field experiment of different amounts of stover mulch under no-tillage on the long-term maize conservation tillage station located in the Mollisols area of Northeast China (built in 2007), including without stover mulch (NT0), 1/3 stover mulch (NT1/3), 2/3 stover mulch (NT2/3) and full stover mulch (NT3/3), and the conservation tillage (plowing without stover mulch, CT) as control. We analyzed phospholipid fatty acid, amino sugar biomarker and soil physicochemical properties at different soil layers (0-5 cm, 5-10 cm, 10-20 cm). The results showed that compared to CT, no-tillage without stover mulch (NT0) did not affect soil organic carbon (SOC), total nitrogen (TN), dissolved organic carbon and nitrogen (DOC, DON), water content, microbial community and their residue. The main effects of no-tillage and stover mulch were found in the topsoil. Specifically, the NT1/3, NT2/3 and NT3/3 significantly increased SOC content by 27.2%, 34.1% and 35.6%, respectively, phospholipid fatty acid content was significantly increased under NT2/3 and NT3/3 by 39.2% and 65.0%, respectively, and NT3/3 significantly increased the content of microbial residue-amino sugar by 47.2% in the depth of 0-5 cm compared with CT. The variations in soil properties and microbial community induced by no-tillage and different amounts stover mulch decreased with soil depth, with almost no difference in the 5-20 cm soil layer. SOC, TN, DOC, DON, and water content were the main factors influencing the composition of the microbial community and the accumulation of microbial residue. Microbial biomass was positively correlated with microbial residue, particularly fungal residue. In conclusion, all stover mulch treatments promoted SOC accumulation to different degrees. When there is sufficient stover, it is advisable to opt for no-tillage with full stover mulch, as it is most conducive to the increases of soil microbial biomass, microbial residue and SOC. In case when the amount of stover is inadequate, however, no-tillage with 2/3 stover mulch can still improve soil microbial biomass and SOC content. This study would provide practical guidance for stover management in conservation tillage and sustainable agricultural development in the Mollisols area of Northeast China.

The Effects of N Addition on Soil Microbial Residues in Croplands and Forests: A Meta-analysis

The Effects of N Addition on Soil Microbial Residues in Croplands and Forests: A Meta-analysis

Distribution Characteristics of Microbial Residues within Aggregates of Fluvo-Aquic Soil under Biochar Application

The use of biochar as a soil amendment has substantial potential to enhance soil quality and carbon sequestration. However, the responses to the addition of biochar based on soil microbial residues are not well understood, particularly at the aggregate level. Herein, a two-year field experiment investigated the characteristics of distribution of microbial residues in calcareous fluvo-aquic soil aggregates (SA) in Henan Province, China. Four treatments were established as follows: no fertilizer (CK), chemical fertilizer (NPK), biochar (BC), and biochar combined with chemical fertilizer (NPK + BC). The results showed that the effects of particle size substantially impacted the microbial residues with 2–0.25 mm SA having the largest contents of amino sugars and microbial residual carbon (MRC), followed by &gt;2 mm SA. Compared with the CK, the NPK treatment markedly enhanced the levels of glucosamine (GluN), galactosamine (GalN), muramic acid (MurA), total amino sugar (TAS), and MRC in the 2–0.25 mm SA by 26.69%, 24.0%, 23.62%, 25.11%, and 24.82%, respectively. The NPK + BC treatment significantly increased the contents of GluN, GalN, TAS, and MRC in the bulk soil and 0.25–0.053 mm SA compared with the NPK treatment. Bacterial biomass and the activity of N-acetyl-glucosaminidase in the bulk soil and SA markedly and positively affected the content of carbon in the amino sugars and microbial residues. Overall, the 2–0.25 mm SA were microenvironments with the largest accumulation of soil microbial residues, and the combined application of NPK + BC was more effective at increasing the accumulation of microbial residues in the SA, which provides an ideal fertilization strategy to improve the soil microenvironment and enhance soil quality.

毛竹扩张对杉木林土壤微生物残体碳积累的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 毛竹扩张对杉木林土壤微生物残体碳积累的影响 DOI: 10.5846/stxb202202030289 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 浙江省"尖兵""领雁"研发攻关计划项目（2022C02036）；浙江省教育厅基金项目（Y202045039）；浙江省自然科学基金项目（LZ22C160001）；浙江农林大学科研发展基金-人才启动项目（2019FR067） Effects of Moso bamboo expansion on accumulation of soil microbial residual carbon in Chinese fir forest Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:亚热带毛竹扩张对杉木林土壤微生物残体碳积累的影响及机制尚不清楚。以毛竹向杉木林扩张带（包括杉木林、杉木-毛竹混交林和毛竹林）的凋落物（O层）和不同发生层土壤（A层、B层和BC层）为研究对象，通过分析凋落物和土壤样品中的氨基糖含量来表征微生物残体碳累积效应，并进一步评价微生物在土壤有机碳（SOC）形成过程中的作用。结果表明：毛竹扩张使杉木林凋落物数量和碳含量显著降低，但是凋落物中真菌残体碳（MRC-f）、细菌残体碳（MRC-b）和微生物残体碳（MRC）含量均显著增加；毛竹扩张显著提高了杉木林SOC、MRC-f、MRC-b和MRC含量，而且在毛竹扩张初期（杉木林演替为杉木-毛竹混交林） MRC-f、MRC-b和MRC在SOC中的比例也显著增加，说明毛竹扩张增强杉木林土壤MRC累积效应的同时，也提高了微生物对有机碳的贡献。而毛竹扩张后期MRC-f、MRC-b和MRC占SOC比例并没有显著变化，意味着毛竹扩张后期MRC和植物源残体碳对SOC含量的提升均有贡献，且两者贡献的相对比例保持不变。土壤MRC含量随着剖面深度的加深逐渐下降，而MRC占SOC比值却随着土壤深度的增加而逐渐升高，说明深层土壤中微生物对有机碳贡献高于表层土壤。研究结果对于理解微生物在亚热带森林SOC形成过程中的作用，科学评估毛竹扩张对亚热带森林生态系统及气候变化的影响，并采取合理的营林措施提升亚热带森林土壤碳汇功能具有重要理论意义。 Abstract:The effects of subtropical Moso bamboo expansion on carbon accumulation in soil microbial residues in Chinese fir forests and its mechanisms were not clear. In this study, the litter (O layer) and soils of different pedogenic horizons (A horizon, B horizon, BC horizon) in the expansion zone of Moso bamboo to Chinese fir forest (including Chinese fir forest, Chinese fir and Moso bamboo mixed forest, and Moso bamboo forest) were studied. We analyzed the amino sugar content in litter and soil samples to characterize accumulation of the microbial residual carbon and further evaluated the role of microorganisms in soil organic carbon (SOC) formation. The results showed that Moso bamboo expansion significantly reduced the amount and carbon content of litter in Chinese fir forests, but significantly increased the content of fungal residual carbon (MRC-f), bacterial residual carbon (MRC-b), and total microbial residual carbon (MRC). Moso bamboo expansion significantly increased SOC, MRC-f and MRC-b and MRC in Chinese fir forests, and the proportion of MRC-f and MRC-b and MRC in SOC increased significantly at the beginning of Moso bamboo expansion (when Chinese fir forests evolved into Chinese fir and Moso bamboo mixed forest). These results indicate that Moso bamboo expansion enhanced the cumulative effect of soil MRC in Chinese fir forests and also increased the microbial contribution to SOC. However, in the late stage of Moso bamboo expansion, the proportion of MRC-f, MRC-b, and MRC to SOC did not change significantly, implying that the contribution of MRC and plant-derived carbon to the SOC content increased at the later stage of Moso bamboo expansion, and the relative proportion of their contribution remained unchanged. The content of MRC gradually decreased with soil depth, while the proportion of MRC to SOC gradually increased with the depth of the soil, implying that the microbial contribution to SOC was higher in deep soils than in surface soils. The results of the study have important theoretical implications for understanding the role of microorganisms in SOC formation in subtropical forests, scientifically assessing the impact of Moso bamboo expansion on the subtropical forest ecosystems and climate change, and adopting reasonable forestry measures to enhance the soil carbon sink function in subtropical forests. 参考文献 相似文献 引证文献

Mean annual temperature and carbon availability respectively controlled the contributions of bacterial and fungal residues to organic carbon accumulation in topsoil across China's forests

AbstractAimSoil organic carbon (SOC) stabilization has become an important topic in recent years in the context of global climate change. Microbial residues represent a significant component of stabilized SOC pools. However, spatial variations in the contributions of bacterial and fungal residues to SOC and their determinants at a continental scale remain poorly understood. We aimed to evaluate the spatial variations and controls of the contributions of microbial residues to SOC in forest topsoil.LocationNorth–south transect in eastern China.Time period2014.Major taxa studiedForest ecosystems.MethodsA total of 195 surface (0–10 cm) soils were sampled from 28 forest sites across tropical and boreal forests in eastern China from July to August to assess how biotic and abiotic factors govern the geographic patterns of the contributions of soil microbial residues (indicated by amino sugars) to SOC.ResultsFungal residues (30.0%) had a greater average contribution to SOC than bacterial residues (15.5%). The contributions of bacterial (CBR) and total microbial residues (CMR) to SOC showed negative latitudinal patterns and were positively correlated with mean annual temperature (MAT). In contrast, the contribution of fungal residues to SOC (CFR) showed no clear geographic or climatic patterns. On average, the CBR (9.7%), CFR (21.1%) and CMR (30.8%) were lower in boreal forests than in other biome forests. SOC concentration negatively mediated CBR, CFR and CMR. The piecewise structural equation model results showed that MAT was the primary driver of the geographic pattern of CBR, whereas SOC and soil carbon : nitrogen ratio were more directly associated with the CFR. Additionally, plant factors and microbial properties (i.e., microbial biomass and composition) played relatively little roles in regulating CBR, CFR and CMR.Main conclusionsThese findings advance the current knowledge of the different geographic patterns of CBR and CFR regulated by different potential mechanisms in forest ecosystems. This highlights that the dynamics of microbial residues could potentially have unexpected consequences for topsoil SOC stocks under climate change.