毛竹扩张对杉木林土壤微生物残体碳积累的影响

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...     

威廉环毛蚯蚓对土壤微生物量及活性的影响

探讨威廉环毛蚯蚓（Ｐｈｅｒｅｔｉｍａ ｇｕｉｌｌｅｌｍｉ）对土壤总微生物量,活性微生物量的影响,蚯蚓处理中（土壤与蚯蚓的比例为５：１,干重：活体重,处理时间为２４ｈ）,用熏蒸提取法测定的土壤总微生物量下降,用底物诱导呼吸法测定的活性微生物量和真菌与细菌比例无显著变化;蚯蚓处理土壤促进了被微生物固持的养分的释放和土壤微生物群体年轻化,增强了微生物的代谢商和纤维素分解活性,结合对文献资料的分析,讨论了     

土地整理对土壤微生物群落多样性的影响

土地整理保证了我国耕地总量的动态平衡和占补平衡,已成为实现国土资源集约利用的主要手段,但整治过程中的强度扰动会对土壤质量产生一定的影响.为了解土地整理对土壤微生物多样性的影响,采用PLFA法研究了土地整理1年(Z1a)、4年(Z4a)后土壤微生物群落多样性的变化.结果表明: 与未整理(Z0)相比,土地整理1年后,土壤pH值提高了14.6%,土壤有机碳质量分数降低了65.4%;各菌群磷脂脂肪酸PLFAs含量和相对丰度均显著下降(P<0.05),下降幅度达43.4%～63.7%和25.2%～53.9%;真菌/细菌(F/B)显著下降(P<0.05),降低了35.9%,而革兰氏阳性菌/革兰氏阴性菌(G⁺/G^-)升高明显,增加了56.1%,均与有机碳的降低和pH值的升高有显著相关关系;土壤微生物多样性Shannon指数和均匀度指数(E)均显著下降,Z0与Z1a、Z4a之间的差异达显著水平;土地整理4年后,表征土壤微生物群落多样性的各指标相比整理1年的样地有所提升,但与未整理样地仍有显著差异.综上,土地整理显著影响着土壤微生物群落的组成,降低了土壤生态系统的稳定性.     

阿维菌素B1a对土壤微生物和蚯蚓的影响

研究了不同阿维菌素B_1a浓度对种土壤微生物生长和呼吸强度的影响及对土壤中蚯蚓的急性毒性.结果表明,土壤中阿维菌素B_1a浓度在83.3 mg·kg^-1以上时对种土壤细菌均表现出明显的抑制作用,但对土壤真菌不表现抑制作用.高浓度阿维菌素B_1a对土壤微生物的呼吸强度有抑制作用,并且在不同土壤其作用有差异.采用滤纸接触试验和人工土壤试验测定阿维菌素对蚯蚓的急性毒性(半数致死量,LD₅₀),接触毒性LD₅₀为.63μg·cm^-2,土壤法试验测定的LD₅₀在处理后第7 d和第1 d分别为2.13和17.06 mg·kg^-1.     

保护性耕作对土壤微生物群落及其介导的碳循环功能的影响

农田生态系统耕作方式显著影响土壤微生物群落结构和功能,进而影响土壤微生物介导的土壤碳循环过程.以免耕结合作物秸秆还田为核心的保护性耕作是提升土壤碳汇功能和肥力的重要措施,其中土壤微生物发挥了关键作用.尽管有较多关于保护性耕作下微生物群落结构与功能的研究,但由于土壤系统的复杂性、环境因素以及微生物群落评价方法的差异性,尚...     

免耕不同秸秆覆盖量对黑土微生物群落及其残留物的影响

为探究免耕和不同秸秆覆盖量下土壤微生物群落组成及残留物的变化规律,依托中国东北黑土区的玉米保护性耕作长期平台(始建于2007年),以传统耕作(翻耕+无秸秆还田)为对照(CT),对免耕结合不同秸秆覆盖量[免耕+无秸秆还田(NT0)、免耕+1/3秸秆覆盖还田(NT1/3)、免耕+2/3秸秆覆盖还田(NT2/3)和免耕+全量秸秆覆盖还田(NT3/3)]下不同土层(0～5、5～10、10～20 cm)土壤理化性质、磷脂脂肪酸和氨基糖的变化特征进行分析。结果表明：与CT相比,免耕无秸秆还田处理(NT0)对土壤有机碳(SOC)、全氮(TN)、可溶性有机碳(DOC)、可溶性有机氮(DON)、含水量、微生物群落及其残留物等均无显著影响;免耕结合秸秆覆盖还田主要影响了土壤表层各指标,与CT相比,0～5 cm土层中NT1/3、NT2/3、NT3/3处理SOC含量分别显著提高了27.2%、34.1%、35.6%,NT2/3和NT3/3处理磷脂脂肪酸含量分别显著提高了39.2%和65.0%,NT3/3处理氨基糖含量(微生物残留物)显著提高了47.2%;免耕不同秸秆覆盖量的土壤理化性质和微生物群落差异随土壤深度...     

不同施肥管理措施对农田土壤中植物和微生物残留组分的影响

在农田生态系统中,施肥是维持和提高土壤有机碳(SOC)水平的重要管理措施。微生物代谢和植物组分存留共同控制着有机碳的截获过程。本研究利用肥料与肥力长期(30年)定位试验,以氨基糖和木质素分别作为微生物和植物残留组分标识物,探讨长期不同施肥处理对黑土农田中微生物和植物残体组分积累及有机碳库的影响。结果表明: 与未施肥处理相比,施用无机肥(单施氮肥或有机无机肥配施)可增加作物生物量和土壤氨基糖的积累,但对木质素和SOC含量无显著影响,说明无机肥施入刺激了微生物底物同化,加速了有机碳和木质素在耕层的周转。与无机肥相比,长期施用有机肥促进了SOC的累积(增幅38.3%),但是氨基糖在土壤有机碳中所占的比例并未发生显著变化,说明微生物残留物对SOC积累的贡献具有饱和性;而有机肥施入增加了木质素在SOC中的比例,即增加了植物残体对SOC长期积累的贡献。与单施有机肥相比,有机无机肥配施增加了微生物残留物对SOC的积累。因此,长期施肥可以调节微生物残留物和植物残留组分的不同积累过程,从而影响SOC的积累和稳定机制。     

土壤微生物碳泵概念体系2.0

土壤微生物在陆地生态系统元素循环中扮演着关键角色,对土壤健康、粮食安全和全球气候变化发挥着重要的调节作用。土壤微生物同化代谢产物对土壤碳储存与有机质维持的贡献不容忽视。近年来,以微生物代谢和死亡残体生成过程为核心提出的土壤微生物碳泵概念体系得到了广泛关注,它主要描述了以土壤异养微生物代谢为驱动的土壤有机碳形成和稳定化过程,是目前陆地生态系统碳固存的重要机制体系与研究热点。本文对该体系的研究进展进行了梳理,并提出了引入自养微生物固碳通道与结合土壤矿物碳泵概念的土壤微生物碳泵概念体系2.0,以期丰富和完善现有的微生物介导的陆地生态系统土壤碳循环与固持机制,为实现我国“双碳”目标提供理论支撑。     

鼎湖山季风常绿阔叶林土壤微生物量碳和有机碳对模拟酸雨的响应

在鼎湖山季风常绿阔叶林设置人工模拟酸雨实验,研究土壤总有机碳含量、微生物量碳含量、土壤p H值和土壤呼吸速率几个指标对不同酸处理梯度(CK:p H值4.5的天然湖水;T1:p H值4.0;T2:p H值3.5;T3:p H值3.0)的响应。结果表明,在模拟酸雨的持续作用下,样地土壤酸化有加剧趋势。2011年的6月(CK:(603.76±46.18)mg/kg,T1:(565.41±44.48)mg/kg,T2:(521.58±30.92)mg/kg,T3:(509.49±19.40)mg/kg)、12月(CK:(488.92±22.71)mg/kg,T1:(379.65±49.46)mg/kg,T2:(346.08±33.81)mg/kg,T3:(318.00±52.35)mg/kg)和2012年6月(CK:(540.48±39.11)mg/kg,T1:(492.30±43.15)mg/kg,T2:(489.65±51.39)mg/kg,T3:(428.53±49.66)mg/kg)3次测定的土壤微生物量碳含量有随模拟酸雨强度增加而显著降低的趋势,高强度的酸处理T3显著低于CK值(P0.05);土壤呼吸速率在各处理中的响应与土壤微生物量碳含量变化一致。由于旱季和湿季的土壤温湿度相差较大,以上各指标在旱湿两季的差异明显,表现为湿季大于旱季。由于土壤总有机碳含量变化缓慢,其在各酸梯度处理下无显著差异(P0.05)。以上结果显示,长期酸雨作用使土壤酸化不断加剧,并降低了土壤微生物量碳的含量,抑制了土壤的呼吸速率,有利于土壤碳的累积,但对土壤总有机碳的影响仍需长期实验研究。     

Plant influences on soil microbial carbon pump efficiency

Microbe-mediated carbon transformation plays an important role in soil carbon sequestration, which is considered to be one of the key strategies to achieve carbon neutrality in the long term. Assessing the efficiency of microbial necromass accumulation relative to plant carbon input or microbial respiration will help to identify ways to promote soil carbon sequestration from an ecosystem perspective.     

Exogenous carbon turnover within the soil food web strengthens soil carbon sequestration through microbial necromass accumulation

Exogenous carbon turnover within soil food web is important in determining the trade-offs between soil organic carbon (SOC) storage and carbon emission. However, it remains largely unknown how soil food web influences carbon sequestration through mediating the dual roles of microbes as decomposers and contributors, hindering our ability to develop policies for soil carbon management. Here, we conducted a ¹³C-labeled straw experiment to demonstrate how soil food web regulated the residing microbes to influence the soil carbon transformation and stabilization process after 11 years of no-tillage. Our work demonstrated that soil fauna, as a “temporary storage container,” indirectly influenced the SOC transformation processes and mediated the SOC sequestration through feeding on soil microbes. Soil biota communities acted as both drivers of and contributors to SOC cycling, with 32.0% of exogenous carbon being stabilizing in the form of microbial necromass as “new” carbon. Additionally, the proportion of mineral-associated organic carbon and particulate organic carbon showed that the “renewal effect” driven by the soil food web promoted the SOC to be more stable. Our study clearly illustrated that soil food web regulated the turnover of exogenous carbon inputs by and mediated soil carbon sequestration through microbial necromass accumulation.     

Increased microbial growth,biomass, and turnover drive soil organic carbon accumulation at higher plant diversity

Species‐rich plant communities have been shown to be more productive and to exhibit increased long‐term soil organic carbon (SOC) storage. Soil microorganisms are central to the conversion of plant organic matter into SOC, yet the relationship between plant diversity, soil microbial growth, turnover as well as carbon use efficiency (CUE) and SOC accumulation is unknown. As heterotrophic soil microbes are primarily carbon limited, it is important to understand how they respond to increased plant‐derived carbon inputs at higher plant species richness (PSR). We used the long‐term grassland biodiversity experiment in Jena, Germany, to examine how microbial physiology responds to changes in plant diversity and how this affects SOC content. The Jena Experiment considers different numbers of species (1–60), functional groups (1–4) as well as functional identity (small herbs, tall herbs, grasses, and legumes). We found that PSR accelerated microbial growth and turnover and increased microbial biomass and necromass. PSR also accelerated microbial respiration, but this effect was less strong than for microbial growth. In contrast, PSR did not affect microbial CUE or biomass‐specific respiration. Structural equation models revealed that PSR had direct positive effects on root biomass, and thereby on microbial growth and microbial biomass carbon. Finally, PSR increased SOC content via its positive influence on microbial biomass carbon. We suggest that PSR favors faster rates of microbial growth and turnover, likely due to greater plant productivity, resulting in higher amounts of microbial biomass and necromass that translate into the observed increase in SOC. We thus identify the microbial mechanism linking species‐rich plant communities to a carbon cycle process of importance to Earth's climate system.     

耕作方式对紫色水稻土有机碳和微生物生物量碳的影响

以位于西南大学的农业部紫色土生态环境重点野外科学观测试验站始于1990年的长期定位试验田为对象,研究了冬水田平作(DP)、水旱轮作(SH)、垄作免耕(LM)及垄作翻耕(LF)等4种耕作方式对紫色水稻土有机碳(SOC)和微生物生物量碳(SMBC)的影响。结果表明,4种耕作方式下SOC和SMBC均呈现出在土壤剖面垂直递减趋势,翻耕栽培下其降低较均匀,而免耕栽培下其富集在表层土壤中。同一土层不同耕作方式间SOC和SMBC的差异在表层最大,随着土壤深度的增加,各处理之间的差异逐渐减小。在0—60 cm剖面中,SOC含量依次为:LM(17.6 g/kg)>DP(13.9 g/kg)>LF(12.5 g/kg)>SH(11.3 g/kg),SOC储量也依次为:LM(158.52 Mg C/hm2)>DP(106.74 Mg C/hm2)>LF(93.11 Mg C/hm2)>SH(88.59 Mg C/hm2),而SMBC含量则依次为:LM(259 mg/kg)>SH(213 mg/kg)>LF(160 mg/kg)>DP(144 mg/kg)。与其它3种耕作方式比较,LM处理显著提高SOC含量和储量以及SMBC含量。对土壤微生物商(SMBC/SOC)进行分析发现,耕作方式对SOC和SMBC的影响程度并不一致。SMBC与SOC、全氮、全磷、全硫、碱解氮、有效磷均呈现极显著正相关(P<0.01),与有效硫呈显著正相关(P<0.05);表明SMBC可以作为表征紫色水稻土土壤肥力的敏感因子。     

Microbial necromass in cropland soils: A global meta-analysis of management effects

Microbial necromass is a large and persistent component of soil organic carbon (SOC), especially under croplands. The effects of cropland management on microbial necromass accumulation and its contribution to SOC have been measured in individual studies but have not yet been summarized on the global scale. We conducted a meta-analysis of 481-paired measurements from cropland soils to examine the management effects on microbial necromass and identify the optimal conditions for its accumulation. Nitrogen fertilization increased total microbial necromass C by 12%, cover crops by 14%, no or reduced tillage (NT/RT) by 20%, manure by 21%, and straw amendment by 21%. Microbial necromass accumulation was independent of biochar addition. NT/RT and straw amendment increased fungal necromass and its contribution to SOC more than bacterial necromass. Manure increased bacterial necromass higher than fungal, leading to decreased ratio of fungal-to-bacterial necromass. Greater microbial necromass increases after straw amendments were common under semi-arid and in cool climates in soils with pH <8, and were proportional to the amount of straw input. In contrast, NT/RT increased microbial necromass mainly under warm and humid climates. Manure application increased microbial necromass irrespective of soil properties and climate. Management effects were especially strong when applied during medium (3–10 years) to long (10+ years) periods to soils with larger initial SOC contents, but were absent in sandy soils. Close positive links between microbial biomass, necromass and SOC indicate the important role of stabilized microbial products for C accrual. Microbial necromass contribution to SOC increment (accumulation efficiency) under NT/RT, cover crops, manure and straw amendment ranged from 45% to 52%, which was 9%–16% larger than under N fertilization. In summary, long-term cropland management increases SOC by enhancing microbial necromass accumulation, and optimizing microbial necromass accumulation and its contribution to SOC sequestration requires site-specific management.     

土壤微生物生物量在团聚体中的分布以及耕作影响

了解土壤微生物在土壤结构体内部的分布对于预测相关的土壤生物化学过程具有重要意义。由于气候、土壤以及耕作的影响,该领域的研究结果存在很大的空间和时间变异,因此有待进行更多的在不同气候和土壤类型下的研究。首次报道亚热带紫色水稻土中微生物生物量在长期不同耕作方式的土壤中不同水稳性团聚体中的分布特征。结果表明微生物生物量在紫色水稻土水稳定性团聚体中的分布模式决定于土壤结构本身,而耕作方式的影响不显著;微生物生物量碳在不同粒级土壤团聚体中无显著性差异,微生物生物量氮与可溶性有机碳在0．25～0．053mm微团聚体中含量最高;垄作免耕显著提高土壤团聚体中的微生物生物量及可溶性有机碳含量,而对微生物生物量及可溶性有机碳在土壤团聚体中的分布模式无显著影响。     

Quantitative assessment of microbial necromass contribution to soil organic matter

Soil carbon transformation and sequestration have received significant interest in recent years due to a growing need for quantitating its role in mitigating climate change. Even though our understanding of the nature of soil organic matter has recently been substantially revised, fundamental uncertainty remains about the quantitative importance of microbial necromass as part of persistent organic matter. Addressing this uncertainty has been hampered by the absence of quantitative assessments whether microbial matter makes up the majority of the persistent carbon in soil. Direct quantitation of microbial necromass in soil is very challenging because of an overlapping molecular signature with nonmicrobial organic carbon. Here, we use a comprehensive analysis of existing biomarker amino sugar data published between 1996 and 2018, combined with novel appropriation using an ecological systems approach, elemental carbon–nitrogen stoichiometry, and biomarker scaling, to demonstrate a suit of strategies for quantitating the contribution of microbe‐derived carbon to the topsoil organic carbon reservoir in global temperate agricultural, grassland, and forest ecosystems. We show that microbial necromass can make up more than half of soil organic carbon. Hence, we suggest that next‐generation field management requires promoting microbial biomass formation and necromass preservation to maintain healthy soils, ecosystems, and climate. Our analyses have important implications for improving current climate and carbon models, and helping develop management practices and policies.     

贺兰山西坡不同海拔梯度土壤氨基糖积累特征

为探明旱区山地不同海拔梯度土壤氨基糖积累特征,明确氨基糖对土壤有机碳库的贡献以及影响因素。以2021年8月在贺兰山西坡不同海拔(1848-2940 m)采集的土壤为研究对象,分析土壤理化性质、微生物群落结构、氨基糖含量、氨基糖对土壤有机碳贡献变化特征以及引起该变化的驱动因素。结果表明:沿海拔梯度上升,土壤理化性质表现出显著差异,土壤含水率、有机碳、全氮表现为升高趋势,pH和容重表现为降低趋势,全磷无明显变化规律。沿海拔梯度上升,土壤真菌、细菌、放线菌以及丛枝菌根真菌磷脂脂肪酸(Phospholipid fatty acids,PLFAs)含量表现为先增加后减少的趋势,在中海拔区域(2110-2360 m)微生物PLFAs含量更高。沿海拔梯度上升,总氨基糖含量和氨基糖单体(氨基葡萄糖、氨基半乳糖、胞壁酸和氨基甘露糖)分别表现为持续增加和先减少后增加的变化趋势,并且总氨基糖和氨基糖单体含量均在最高海拔达到峰值,中海拔区域真菌和细菌残体碳对土壤有机碳的贡献率均小于高海拔(2707-2940 m)和低海拔(1848-1910 m),且在不同海拔梯度上真菌残体碳对土壤有机碳贡献率占据主导地位。方差分解结果显示,土壤理化性质和微生物PLFAs含量共同解释了土壤氨基糖含量及对有机碳贡献率的55.2%,其中土壤理化性质解释变异的52.9%,微生物PLFAs含量解释变异的26.9%,冗余分析同步验证土壤理化性质是影响氨基糖及氨基糖对土壤有机碳贡献率的主要因素。本研究结果揭示了贺兰山西坡微生物驱动土壤有机碳存储与转化机制,可为进一步研究旱区山地微生物残体对土壤有机碳的贡献提供理论依据。