Vegetation structure,species life span,and exotic status elucidate plant succession in a limestone quarry reclamation

An understanding of the processes involved in plant succession is pivotal in achieving an effective site restoration. In a former limestone quarry (northeastern Italy), we explored the effects of a technical reclamation on the plant community using changes in cover of vegetation layers and two sensitive plant traits (i.e. exotic status and life span), with a chronosequence approach. Four reclaimed areas of different ages (from 8 to 35 years old) and natural vegetation in the surroundings were investigated with seven permanent plots each, for a total of 35. Changes in vegetation layers and species richness of both exotic status and life span were analyzed by generalized linear (mixed) models. Relations with plant community assembly were also considered, using a multivariate approach. Both vegetation layers and plant traits were affected by the age of reclaimed areas, evidencing the main changes in plant succession. Annual and exotic species decreased toward the mature stages of reclamation and target vegetation, whereas overall plant diversity (species richness) was stable. Our findings show that both vegetation layer changes and plant traits can be used to assess the degree to which reclamation efforts produce results that approach the restoration of a natural vegetation reference. Implementation of management practices aimed at favoring native perennial species (e.g. appropriate seed mixtures, mowing, tree, and shrub planting) could limit weed‐control efforts, representing a reasonable trade‐off between biodiversity promotion and invasive plant control.     

萘对川西亚高山森林土壤微生物量、丰度和磷脂脂肪酸的影响

萘作为土壤动物化学抑制剂已在土壤动物生态功能的研究中广泛使用,但其非目标效应使其应用仍存在很大的不确定性。为了解在亚高山森林土壤应用萘抑制土壤动物群落的非目标效应,以川西亚高山森林土壤为研究对象,采用微缩实验研究了土壤微生物生物量、丰度和磷脂脂肪酸对萘胁迫的短期响应。结果表明,萘处理和对照的土壤微生物生物量碳(MBC)、真菌丰度以及细菌、真菌、革兰氏阳性菌(G~+)和革兰氏阴性菌(G~-)PLFAs含量在整个培养期间表现为降低的变化趋势,二者的土壤微生物生物量碳和G~+PLFAs含量以培养52d最低,细菌、真菌和G~-PLFAs含量以培养的45d最低。萘处理和对照的微生物生物量氮(MBN)含量表现出先升高后降低的动态,微生物生物量碳氮比(MBC/MBN)则表现为相反趋势。对照的真菌/细菌PLFAs比值呈现先升高后降低的动态,以培养的17d最高,但萘处理的真菌/细菌PLFAs比值无明显变化规律;萘处理的G~+/G~-PLFAs比值表现为降低的变化趋势,对照的G~+/G~-PLFAs比值表现为先降低后升高的趋势。萘处理仅显著影响了G~+/G~-PLFAs比值,但萘处理和采样时间的交互作用显著影响MBC/MBN、细菌丰度、真菌/细菌丰度比以及细菌、真菌的PLFAs含量、真菌/细菌PLFAs比值、G~+/G~-PLFAs比值。萘作为土壤动物抑制剂对川西亚高山森林土壤微生物群落的非目标效应具有时间变异性。     

Walnut development affects chemical composition and codling moth performance

1 We investigated for early and late blooming walnut cultivars in California whether variation in nut phenology resulted in differences in nutritional quality and whether this, in turn, affected the performance of the codling moth, Cydia pomonella (L.), and the extent of nut damage. 2 Mid‐season, during the period of nut growth, nuts from the early cultivars were larger than those from the late cultivars and had higher nitrogen content in both husk and kernel tissue, while kernel phenolic content was significantly lower. No major differences were observed later in the season after nuts from all cultivars had reached their final size. 3 Throughout the season establishment of neonate larvae was highest on nuts from the early cultivars but this was only significantly so at the beginning of the third codling moth generation. During the second codling moth generation (mid season) relative growth rates of third‐instar larvae were significantly higher on early than on late cultivars. Nut damage in the field was also significantly greater on early than on late cultivars during generation 2, while no significant differences were observed during generation 3. 4 The data suggest that the variation in codling moth damage among walnut cultivars is related to bloom phenology due to the influence of nut phenology on larval performance.     

氮添加土壤微生物群落结构影响微生物碳利用效率

尽管近年来中国氮(N)沉降水平逐渐趋于稳定,但中国东南地区N沉降相比于其他地区仍处于较高水平。N沉降对陆地生态系统碳循环过程的影响不容忽视。微生物碳利用效率(CUE)是指微生物将吸收的碳转化为生物量碳的效率,高微生物CUE意味着高土壤有机碳存储潜力。因此,探究N沉降背景下微生物CUE的变化将有助于进一步认识陆地生态系统土壤碳存储的变化。然而,目前关于N沉降下微生物群落结构的变化如何影响微生物CUE鲜有报道。在福建省泉州市戴云山国家级自然保护区的罗浮栲林通过N添加模拟N沉降。实验共包括三个N添加处理：对照(CT,+0 kg hm^-2 a^-1)、低氮(LN,+40 kg hm^-2 a^-1)和高氮(HN,+80 kg hm^-2 a^-1)。测定不同处理土壤基本理化性质、微生物生物量、酶活性和CUE,并使用高通量测序对微生物群落结构和多样性进行测定。结果表明,N添加显著影响微生物CUE,随着N添加水平的增加,CUE逐渐增加;相反,土壤pH、可提取有机碳(EOC)和微...     

Above‐ and belowground linkages in Sphagnum peatland: climate warming affects plant‐microbial interactions

Peatlands contain approximately one third of all soil organic carbon (SOC). Warming can alter above‐ and belowground linkages that regulate soil organic carbon dynamics and C‐balance in peatlands. Here we examine the multiyear impact of in situ experimental warming on the microbial food web, vegetation, and their feedbacks with soil chemistry. We provide evidence of both positive and negative impacts of warming on specific microbial functional groups, leading to destabilization of the microbial food web. We observed a strong reduction (70%) in the biomass of top‐predators (testate amoebae) in warmed plots. Such a loss caused a shortening of microbial food chains, which in turn stimulated microbial activity, leading to slight increases in levels of nutrients and labile C in water. We further show that warming altered the regulatory role of Sphagnum‐polyphenols on microbial community structure with a potential inhibition of top predators. In addition, warming caused a decrease in Sphagnum cover and an increase in vascular plant cover. Using structural equation modelling, we show that changes in the microbial food web affected the relationships between plants, soil water chemistry, and microbial communities. These results suggest that warming will destabilize C and nutrient recycling of peatlands via changes in above‐ and belowground linkages, and therefore, the microbial food web associated with mosses will feedback positively to global warming by destabilizing the carbon cycle. This study confirms that microbial food webs thus constitute a key element in the functioning of peatland ecosystems. Their study can help understand how mosses, as ecosystem engineers, tightly regulate biogeochemical cycling and climate feedback in peatlands     

内源微生物驱油及其对油藏微生物活动的影响

【目的】新疆油田六中区为典型水驱普通稠油油藏,水驱效果较差,油藏具有丰富的内源微生物,本研究通过分析内源微生物驱油对油藏微生物活动的影响,确定内源微生物驱油技术在该类油藏的应用潜力。【方法】采用高通量测序及分析化学技术,系统研究实施内源微生物驱油技术后油藏细菌群落结构组成、细菌总数和功能菌群的浓度以及采出液的流体性质,总结内源微生物驱油对油藏微生物活动的影响。【结果】现场试验注入激活剂和空气后,内源微生物被显著激活,细菌群落结构发生明显变化,细菌总数及功能菌群浓度普遍提高了2–3个数量级;各种内源微生物代谢活动显著增强,与地层流体相互作用后,原油明显被乳化,最终石油采收率提高5.2%。【结论】对于内源微生物较为丰富的水驱普通稠油油藏,内源微生物驱油技术对油藏微生物活动的影响显著,具有显著的技术优势和较大的应用潜力,微生物群落结构、功能菌群浓度及其相关代谢产物可以作为评价内源微生物驱油现场激活效果的重要指标,为其他内源微生物驱油现场试验提供技术参考。     

亚热带森林土壤微生物生物量及群落功能特征的城乡梯度变化

土壤微生物在土壤养分循环以及生物地球化学循环中起着重要作用,土壤微生物对环境变化响应灵敏.为研究城乡梯度环境变化对亚热带森林土壤微生物的影响,本研究选取合肥市大蜀山国家森林公园(城市林)、紫蓬山国家森林公园(远郊林)、六安市万佛山(乡村自然林)为样地,分析比较其微生物生物量碳(MBC)、微生物生物量氮(MBN)及微生物...     

森林类型对土壤有机质、微生物生物量及酶活性的影响

以澳大利亚南昆士兰州典型森林类型——湿地松、南洋杉和贝壳杉林为对象,开展土壤可溶性有机碳和氮(SOC和SON)、微生物生物量碳和氮(MBC和MBN),以及土壤酶活性的研究,剖析森林类型对土壤质量的影响.结果表明:不同林型土壤SOC、SON含量分别在552 ～1154 mg·kg-1和20.11～57.32mg·kg-1;MBC、MBN分别在42～149 mg·kg-1和7～35 mg·kg-1.MBC、MBN之间呈显著相关.土壤几丁质酶、酸性磷酸酶、碱性磷酸酶和β-葡萄糖苷酶的活性分别为2.96 ～7.63、16.5 ～29.6、0.79 ～ 3.42和3.71 ～9.93 μg ·g-1·h-1,亮氨酸氨肽酶活性为0.18～0.46 μg·g-1·d-1.不同林型土壤SOC含量,以及土壤几丁质酶和亮氨酸氨肽酶活性为湿地松林、南洋杉林、贝壳杉林依次降低;而SON含量为南洋杉林＞贝壳杉林＞湿地松林,且南洋杉林的SON含量显著(P＜0.05)高于湿地松林;MBC和MBN以及碱性磷酸酶活性为贝壳杉林＞湿地松林＞南洋杉林;酸性磷酸酶和β-葡萄糖苷酶活性为湿地松林＞贝壳杉林＞南洋杉林.在土壤生物代谢因子中,MBC、MBN、SON和亮氨酸氨肽酶对不同森林类型土壤影响较大.     

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.     

土地利用方式对西双版纳热带森林土壤微生物生物量碳的影响

2006年1月至2007年9月,通过去除凋落物和切根控制试验,研究了热带森林不同土地利用方式(次生林/橡胶林)对西双版纳热带森林土壤微生物生物量碳的影响.结果表明:次生林转变为橡胶林后,土壤养分及植物碳输入均明显减少,土壤微生物生物量碳显著降低;两种林型雨季土壤微生物生物量碳均高于干季,其中次生林土壤微生物生物量碳与土壤温度呈显著正相关,而橡胶林则与土壤湿度呈正相关关系;次生林土壤微生物生物量碳受植物根系养分输入的调控,地上凋落物数量的影响较小,土壤微生物生物量碳与细根生物量及其C、N输入量呈显著正相关;橡胶林细根生物量及其C、N输入量,以及地上凋落物均未显著影响土壤微生物生物量碳.橡胶种植导致土壤养分含量和土壤pH值降低,加上严重的人为干扰,土壤微生物生物量碳减少,且其调控因素发生显著变化,最终可能影响土壤的其他生态过程.     

亚热带森林转换对土壤微生物呼吸及其熵值的影响

土壤微生物呼吸及其熵值是表征土壤质量变化的敏感性指标,不仅能衡量土壤微生物碳利用效率,还能揭示土壤有机碳的变化。通过比较亚热带米槠天然林转换为马尾松人工林和杉木人工林后土壤微生物呼吸速率、土壤微生物生物量碳以及微生物熵、代谢熵的差异,研究亚热带森林转换对土壤微生物碳利用效率的影响。研究结果显示:(1)与天然林相比,马尾松人工林0—10 cm土壤微生物呼吸速率上升32%(P<0.05),马尾松人工林和杉木人工林10—20 cm土壤微生物呼吸速率分别下降26%和24%(P<0.05);但在20—40 cm土层和40—60 cm土层,天然林土壤微生物呼吸速率比马尾松人工林分别高50%和43%;(2)马尾松人工林和杉木人工林0—10 cm土层土壤微生物生物量碳(MBC)比天然林分别下降19%和40%(P<0.05),但马尾松人工林10—20 cm土壤MBC上升29%(P<0.05);(3)人工林表层土壤微生物熵与天然林没有显著差异,但与天然林相比,杉木人工林和马尾松人工林20—40 cm土层土壤微生物熵分别下降51%和71%(P<0.05),40—60 cm分别下...     

红茶菌群中菌株相互作用影响菌体生长和代谢

[背景]红茶菌是一种由细菌和酵母菌共生发酵而成的传统茶饮料.该饮料中含有多种有益人体健康的营养物质,具有促进消化、消炎、抗菌、抗糖尿病等生理作用.这些有益的代谢物是以醋酸菌和酵母菌为主的微生物相互作用而产生的.因此,红茶菌是一个优良的研究微生物相互作用的体系.[目的]分析不同菌株单独培养和混合培养对菌体生长和代谢产物的...     

Salinity affects microbial activity and soil organic matter content in tidal wetlands

Climate change‐associated sea level rise is expected to cause saltwater intrusion into many historically freshwater ecosystems. Of particular concern are tidal freshwater wetlands, which perform several important ecological functions including carbon sequestration. To predict the impact of saltwater intrusion in these environments, we must first gain a better understanding of how salinity regulates decomposition in natural systems. This study sampled eight tidal wetlands ranging from freshwater to oligohaline (0–2 ppt) in four rivers near the Chesapeake Bay (Virginia). To help isolate salinity effects, sites were selected to be highly similar in terms of plant community composition and tidal influence. Overall, salinity was found to be strongly negatively correlated with soil organic matter content (OM%) and C : N, but unrelated to the other studied environmental parameters (pH, redox, and above‐ and below‐ground plant biomass). Partial correlation analysis, controlling for these environmental covariates, supported direct effects of salinity on the activity of carbon‐degrading extracellular enzymes (β‐1, 4‐glucosidase, 1, 4‐β‐cellobiosidase, β‐D‐xylosidase, and phenol oxidase) as well as alkaline phosphatase, using a per unit OM basis. As enzyme activity is the putative rate‐limiting step in decomposition, enhanced activity due to salinity increases could dramatically affect soil OM accumulation. Salinity was also found to be positively related to bacterial abundance (qPCR of the 16S rRNA gene) and tightly linked with community composition (T‐RFLP). Furthermore, strong relationships were found between bacterial abundance and/or composition with the activity of specific enzymes (1, 4‐β‐cellobiosidase, arylsulfatase, alkaline phosphatase, and phenol oxidase) suggesting salinity's impact on decomposition could be due, at least in part, to its effect on the bacterial community. Together, these results indicate that salinity increases microbial decomposition rates in low salinity wetlands, and suggests that these ecosystems may experience decreased soil OM accumulation, accretion, and carbon sequestration rates even with modest levels of saltwater intrusion.     

Substrate and environmental controls on microbial assimilation of soil organic carbon: a framework for Earth system models

A mechanistic understanding of microbial assimilation of soil organic carbon is important to improve Earth system models’ ability to simulate carbon‐climate feedbacks. A simple modelling framework was developed to investigate how substrate quality and environmental controls over microbial activity regulate microbial assimilation of soil organic carbon and on the size of the microbial biomass. Substrate quality has a positive effect on microbial assimilation of soil organic carbon: higher substrate quality leads to higher ratio of microbial carbon to soil organic carbon. Microbial biomass carbon peaks and then declines as cumulative activity increases. The simulated ratios of soil microbial biomass to soil organic carbon are reasonably consistent with a recently compiled global data set at the biome level. The modelling framework developed in this study offers a simple approach to incorporate microbial contributions to the carbon cycling into Earth system models to simulate carbon‐climate feedbacks and explain global patterns of microbial biomass.     

Effect of exposure to atmospheric pollution on microbial activity in soil

Summary Surface samples of a brown earth soil, showing signs of podzolization were transferred from an unpolluted woodland site and exposed to heavy atmospheric pollution for a period of one year. Although exposure resulted in a decrease in soil pH from 4.2 to 3.7, no significant changes in microbial numbers; nitrification rate; respiration rate; solubilization of insoluble phosphate; or the activity of a range of soil enzymes occurred. The rate of ammonification was, however, higher in the exposed than the control soil.Microbial activity in the unpolluted soil was not, therefore, substantially impaired by exposure to heavy atmospheric pollution, despite the fact that the pH of the soil was reduced.     

秸秆预处理对土壤微生物量及呼吸活性的影响

冬小麦秸秆经8．0g·L^-1H2O2(pH11．0)溶液、12．5g·L^-1 NaOH溶液或H2SO4溶液浸泡8h并80℃烘干后,与无机N一起加入土壤,进行室内25℃恒温培养试验,在不同时间测定土壤微生物量C、N和CO2释放速率。结果表明,培养前期,秸秆预处理使土壤微生物量C数量增加了1．0～1．4倍,但降低了土壤微生物的呼吸活性;培养后期,NaOH和H2SO4处理使土壤微生物量C分别下降了28％和42％,但增加了土壤微生物的呼吸活性;H2O2处理则使土壤微生物量N增加90％;土壤微生物区系中的真菌比例在不同时刻有所增加,表明将秸秆预处理后施入土壤,将对土壤中微生物数量和呼吸活性产生一定影响。     

土壤微生物总活性研究方法进展

微生物总活性是指在某一时段内微生物所有生命活动的总和,它直接决定着微生物行使生理、生态功能的能力,是微生物学研究的热点,也是难点。迄今为止,还没有建立直接测定微生物总活性的方法,只能用一些相关指标来间接反映它。目前常用的指标主要包括微生物的呼吸速率、生长速率以及胞内RNA含量等。与其它一些基质和环境相比,测定土壤中的微生物总活性更为困难。通过总结研究土壤微生物总活性常用的3种方法,在简略概括传统的土壤微生物呼吸测定法的基础上,详细介绍了放射性同位素标记法和RNA直接表征法的原理和操作流程,整理归纳了一些重要应用案例,比较分析了不同方法的优缺点,以期为选择研究土壤微生物总活性的适宜方法提供依据。     

暖温带森林土壤微生物量、群落结构和活性对植物地下碳源的响应

该研究以典型的亚热带—温带过渡区森林为对象,采用野外过程监测和控制试验相结合的方法,利用磷脂脂肪酸和土壤胞外酶活性分别表征土壤微生物群落结构和活性,并结合微环境因子,重点探究土壤微生物生物量、群落结构和活性对植物地下碳输入的响应特征。结果表明：在观测周期内,处理均能显著降低三组年龄段林分的土壤微生物量碳,其变化幅度在－8.72％~－5.72％之间,其中在80年的林分中降幅最大,而在160年的林分中降幅最小;微生物量氮的变化规律与相应的微生物量碳的变化规律相似,但与对照相比其差异性均未达到显著性水平;另外,经壕沟处理2~4个月后,所有林分的土壤微生物量碳和氮与对照相比出现增加的现象。处理均能对三组年龄段林分的土壤微生物群落结构产生不同程度的影响,其中40年林分的土壤微生物群落对处理的响应程度要高于另外两个年龄段的林分;与对照相比,壕沟处理样方的腐生真菌的相对丰富度均下降明显,其中在40年和80年林分中的下降幅度达到显著水平,而细菌、放线菌和丛枝菌根真菌均无明显变化;壕沟处理样方的水解酶(β-葡萄糖苷酶和N-乙酰-葡萄糖苷酶)活性均显著下降,而氧化酶(酚氧化酶和过氧化物酶)活性的变化相对较小,除80年的林分外,其余林分均不显著。此外,处理均不能显著影响土壤的含水量和温度。该研究结果为初步阐明全球气候变化背景下森林土壤微生物结构及其功能的变化特征以及更加精确预测未来森林土壤碳的变化趋势提供了科学依据。     

油松-辽东栎混交林地表凋落物与氮添加对土壤微生物生物量碳、氮及其活性的影响

2010年9月-2011年10月,在山西省灵空山油松和辽东栎混交林样地采取随机区组设计,研究了地表凋落物和氮添加处理对土壤微生物生物量碳、氮和微生物活性的影响.凋落物处理包括:剔除凋落物(N)、叶凋落物加倍(L)、枝果凋落物加倍(B)和混合凋落物加倍(LB);氮添加量分别为0(N0)、5 g· m-2·a-1(N1)和10 g·m-2·a-1(N2).结果表明:剔除地表凋落物且无氮添加时,油松和辽东栎混交林地的土壤有机碳(SOC)含量显著降低,其他试验处理间对SOC的影响无显著差异.土壤微生物生物量碳(MBC)、氮(MBN)及其活性(MR)的变化范围依次为:262.42 ～ 873.16 mg·kg-1、73.55 ～ 173.85 mg·kg-1和2.38～3.68mg·kg-1·d-1.MBC、MBN和MR两两间呈极显著正相关.氮添加对MBC、MBN和MR均无显著影响;凋落物处理对MR影响显著,表现为混合凋落物加倍处理的MR最高,叶凋落物加倍处理次之,剔除凋落物处理最低,而对MBC和MBN无显著影响.凋落物和氮添加处理在整个试验过程中未表现出交互作用.短期的氮添加处理和森林地表凋落物变化对土壤微生物过程的影响有限.