土壤原生动物在环境监测中的应用

土壤原生动物具有丰富的种类多样性和巨大的生物量,在土壤生态系统中具有十分重要的地位。因此,其种类和数量的变化可指示环境质量的状况及发展趋势。与其它土壤生物相比,原生动物的一些特征使其更利于成为监测生物。土壤原生动物各类群在环境监测中的作用是不同的。有壳肉足虫和纤毛虫更适合作为土壤环境的指示生物。土壤原生动物在农田生态系统、森林生态系统等环境监测中已经有了一些应用,但与在水体环境监测中获得广泛应用的水生原生动物相比,土壤原生动物用于环境监测才刚刚起步。土壤原生动物分类学研究的滞后和方法学上的欠缺是阻碍其作为监测生物的瓶颈。相信随着这些问题的逐步解决,土壤原生动物在环境监测中必将发挥越来越大的作用。     

长江洞庭湖口原生动物的生态学研究

对长江洞庭湖口原生动物群落为期三年的研究结果：种类组成、季节分布、优势种类、丰度的季节变化等,同时还依据食性分析了各种类的功能营养类群,并对河流中原生动物的来源、长江中上游地区原生动物种类组成规律、原生动物功能营养类群和优势种类在河流污染监测中的指示作用等进行了讨论。     

长江洞庭湖口原生动物的生态研究

对长江洞庭湖口原生动物群落为期三年的研究结果,种类组成,季节分布、优势种类、丰度的变化等,同时还依据食性分析了各种类的功能营养类群,并对河流中原生动物地来源、长江中上游地区原生动物种类组成规律,原生动物功能营养类群和优势在在河流污染监测中的指示作用等进行了讨论。     

PFU原生动物群落生物监测的生态学原理与应用

原生动物是水生生态系统食物链中重要环节 ,发挥着十分重要的生态功能作用。在水环境质量变化评价与发展趋势预测中 ,与其它较高等生物类群比较 ,PFU原生动物群落在水质监测应用方面显示了诸多优点。系统地阐述了原生动物在水生生态系统中的地位与作用 ,重点介绍了原生动物评价水体污染的生态学基础及其优点和 PFU原生动物群落特征及其在水质监测应用中的优势。通过对国内外不同水质类型 PFU原生动物群落生物监测的典型案例研究 ,进一步论证了 PFU原生动物群落生物监测的生态学原理与应用优势     

荒漠草原土壤动物与降雨关系研究现状

在全球性气候变化背景下,极端降雨事件频发,总结土壤动物多样性与降雨变化间的关系及其响应机制,有助于理解全球变化对土壤生态系统结构与功能的作用过程,对于探讨陆地生态系统应对全球变化具有重要科学意义。荒漠草原生态系统极度脆弱,对气候变化敏感,但是关于荒漠草原土壤动物与降雨变化间关系的研究报道比较少,严重制约了对荒漠草原生态系统的有效管理和可持续利用。本文从地上、地面和地下3个方面总结了土壤动物和降雨变化间的关系,并就荒漠草原土壤动物应对气候变化研究提出了一些建议。研究表明,降雨变化直接影响土壤动物群落结构;土壤动物对降雨变化反应强烈,不同动物类群产生了积极的响应规律;某些土壤动物类群对于降雨变化还具有重要指示作用。在荒漠草原生态系统中,今后需要从降雨变化对土壤动物产生的长期影响、土壤动物对降雨变化的适应方式和某些动物类群对土壤水分敏感性以及土壤动物与气候变化间的互为反馈关系等方面加强研究。     

土壤原生动物

土壤中存在着原生物动物,土壤原生动物起源淡水,尽管土壤原生动物与水生生动物有着千丝万继的联系,但由于对土壤环境的长期适应,它在群落组成,形态学,生理学及分布上形成了自身的特征,土壤原生动物在土壤生态系统中起着重要作用,具有重要意义。     

土壤原生动物

土壤原生动物早已被认为是土壤有机整体的一部分,尤其是在陆地生态系统的物质分解过程中所起到的重要作用,日益引起广泛的关注。因此,本文仅从土壤原生动物的种类与分布,环境对土壤原生动物的影响和原生动物在土壤中的作用三方面做一简要综述。     

植物功能性状与湿地生态系统土壤碳汇功能

湿地生态系统碳平衡对气候变化极为敏感,是陆地生态系统碳循环响应全球变化的重要环节。然而,湿地生态系统碳汇调节机制仍不十分清楚,并且对影响因子的研究多集中在非生物因子上。综述了植物功能性状和功能性状多样性对湿地生态系统土壤碳汇功能的影响,阐明了生物因子对生态系统碳循环响应全球变化的重要性,介绍了植物功能性状对生态系统碳输入和输出过程的影响,简述了植物功能性状多样性的研究现状及其在指示生态系统碳汇功能现状和预测未来趋势等方面的应用。从优势植物、植物种间关系和植物-微生物种间关系3方面总结了植物功能性状多样性直接和间接影响生态系统碳循环的途径。展望了植物功能性状和功能性状多样性与湿地生态系统土壤碳汇功能的研究前景。     

土壤线虫对环境污染的指示作用

线虫作为土壤中型动物区系的一部分,在土壤生态系统中发挥着重要的作用,因其所特有的生物特性,使其广泛地应用于土壤健康状况的指示研究中．根据国内外的研究现状,分别对典型线虫在土壤污染指示与诊断中的应用和线虫群落的各种指数指标法(如成熟指数、多样性指数、相似度指数、关键种法、N／C比值和生理指标法)及其特点进行概述,论述了土壤动物线虫及其对污染环境的生物指示作用。提出土壤线虫作为一种有效的生态毒理诊断指标具有良好的发展前景．     

土壤呼吸对降雨变化和氮沉降交互作用响应的研究进展

土壤呼吸作为陆地生态系统碳循环的关键过程,对大气CO₂浓度变化有直接影响。研究其如何响应降雨变化、氮沉降增加等全球变化因子,成为近年全球变化领域的热点与难点。与土壤呼吸响应降雨变化或氮沉降增加单个因子相比,研究土壤呼吸对这两个因子交互作用的响应更接近真实的自然环境,可更准确地预估未来土壤碳排放的变化趋势。目前,相关研究涉及全球不同的陆地生态系统,从土壤、微生物和植物层面对其响应机理进行揭示。本文从土壤呼吸及其组分、相关的土壤性质、微生物及植物因素方面,较全面地梳理了不同陆地生态系统土壤呼吸响应降雨变化和氮沉降增加交互作用的研究进展,指出了现有研究中的不足及今后需加强的研究方向,以期为进一步揭示土壤呼吸对降雨变化和氮沉降增加交互作用的响应规律及机制提供参考。     

Selective grazing of methanotrophs by protozoa in a rice field soil

Biological methane oxidation is a key process in the methane cycle of wetland ecosystems. The methanotrophic biomass may be grazed by protozoa, thus linking the methane cycle to the soil microbial food web. In the present study, the edibility of different methanotrophs for soil protozoa was compared. The number of methanotroph-feeding protozoa in a rice field soil was estimated by determining the most-probable number (MPN) using methanotrophs as food bacteria; naked amoebae and flagellates were the dominant protozoa. Among ten methanotrophic strains examined as a food source, seven yielded a number of protozoa comparable with the yield with Escherichia coli [10⁴ MPN (g soil dry weight)⁻¹], and three out of four Methylocystis spp. yielded significantly fewer numbers [10²–10³ MPN (g soil dry weight)⁻¹]. The lower edibility of the Methylocystis spp. was not explained either by their growth phase or by harmful effects on protozoa. Incubation of the soil under methane resulted in a higher number of protozoa actively grazing on methanotrophs, especially on the less-edible group. Protozoa isolated from the soil demonstrated a grazing preference on the different methanotrophs consistent with the results of MPN counts. The results indicate that selective grazing by protozoa may be a biological factor affecting the methanotrophic community in a wetland soil.     

Protozoan Response to the Addition of Bacterial Predators and Other Bacteria to Soil

Representatives of several categories of bacteria were added to soil to determine which of them might elicit responses from the soil protozoa. The various categories were nonobligate bacterial predators of bacteria, prey bacteria for these predators, indigenous bacteria that are normally present in high numbers in soil, and non-native bacteria that often find their way in large numbers into soil. The soil was incubated and the responses of the indigenous protozoa were determined by most-probable-number estimations of total numbers of protozoa. Although each soil was incubated with only one species of added bacteria, the protozoan response for the soil was evaluated by using most-probable-number estimations of several species of bacteria. The protozoa did not respond to incubation of the soil with either Cupriavidus necator, a potent bacterial predator, or one of its prey species, Micrococcus luteus. C. necator also had no effect on the protozoa. Therefore, in this case, bacterial and protozoan predators did not interact, except for possible competition for bacterial prey cells. The soil protozoa did not respond to the addition of Arthrobacter globiformis or Bacillus thuringiensis. Therefore, the autochthonous state of Arthrobacter species in soil and the survival of B. thuringiensis were possibly enhanced by the resistance of these species to protozoa. The addition of Bacillus mycoides and Escherichia coli cells caused specific responses by soil protozoa. The protozoa that responded to E. coli did not respond to B. mycoides or any other bacteria, and vice versa. Therefore, addition to soil of a nonsoil bacterium, such as E. coli, did not cause a general increase in numbers of protozoa or in protozoan control of the activities of other bacteria in the soil.     

上海城市绿化带土壤蜱螨目群落结构与生物指标

通过对上海城市绿化带6种典型环境土壤的调查,研究了城市绿化带土壤蜱螨目和其它小节肢类土壤动物的群落结构及其与土壤环境的关系。结果表明:城市绿化带土壤蜱螨目群落结构特征在很大程度上有别于自然土壤和农业土壤,反映了城市绿化带为一新型生态系统;城市绿化带土壤质量较差,但土壤蜱螨目仍然保持了较高的种类丰富度和密度,是恶劣环境评价的较好指示生物类群;除蜱螨目密度和种类丰富度外,甲螨亚目的无翼类、低等类和中气门亚目的种类丰富度和密度以及中气门亚目雌雄性比对环境变化敏感,且这些指标特征对不同环境土壤质量的评价结果基本一致,是较好的生物指标。     

树种多样性对土壤微生物群落结构和元素生物地球化学循环的影响研究进展

森林是陆地生态系统的重要组成部分,其巨大的生产力和生态服务功能对人类的生存和发展至关重要。森林树种多样性增加能够显著提高森林生产力,关于树种多样性如何影响地下生物多样性及生态功能逐渐受到国内外学者的广泛关注。从土壤微生物及其介导的元素生物地球化学循环这一视角出发,综述了树种多样性对土壤细菌和真菌多样性、群落结构及功能的影响,提出需要进一步深入研究的方向。总体来说,树种多样性有利于增加土壤细菌生物量和多样性,是预测病原性真菌和菌根真菌多样性及群落结构的重要生物因子。树种多样性能增加土壤有机碳储量,增强森林土壤的甲烷氧化能力,并提高土壤磷周转速率及有效磷含量。关于树种多样性对森林土壤氮循环的影响需考虑多样性假说和质量比假说的相对贡献。今后应加强树种多样性对多个营养级之间相互作用的研究;关注树种多样性对生态系统多功能的影响;加强学科交叉,引入微生物种群动态模型和气候模型等模型预测方法,研究树种多样性对全球气候变化的应对机制,以期促进地上植物多样性与地下生态系统功能关系的研究,增强森林生态系统应对未来全球环境变化的能力。     

中国典型地带土壤原生动物食性的观察

报道了中国６人典型地带土壤原生动物的食性观察结果,并就观察结果进行了讨论和分析。根据食性或营养方式,将鉴定到的２０９种土壤原生动物分为８个功能营养类群－－自养者、食细菌者、肉食者、食碎屑者、食真菌者、植食者、杂食者和腐生性营养者。对鉴定到的各分类类群的食性进行了讨论和分析。     

Effectiveness of naturally occurring Aphis gossypii on tomato plants as a bio-indicator for heavy metals in Riyadh and Hafar Al-Batin,Saudi Arabia

Although certain pollutants can be biologically degraded by microorganisms, rendering their impact short-term, others can not be impaired, such that their effect persists. The present study evaluates the effectiveness of using a field-collected aphid, Aphis gossypii, as a bio-indicator for heavy metals in tomato farms in Riyadh and Hafar Al-Batin, Saudi Arabia. Heavy metals were selected (Cd, Cu, Zn, and Pb) and measured for comparative screening in field-collected plants, soil, and aphids using inductively coupled plasma-mass spectrometry (ICP-MS). Field-collected aphids from both studied regions were identified as Aphis gossypii. In Riyadh, there was no significant difference observed for Cd, Cu, and Zn for all experimental samples, while, Pb was showed differences among samples especially tomato leaves None of the studied samples in Hafar Al-Batin were showed statistically significant differences in Cd, in reverse to significant differences in the other heavy metals. Comparing concentrations of selected heavy metals between the two studied regions was showed that neither region showed a significant difference in heavy metals except for Cu. This study demonstrates that tomato leaf samples showed the highest concentrations of most studied heavy metals, followed by soil, then aphids. Aphids were utilized as a bio-indicator of heavy metals in the studied regions.     

Population Dynamics of Active and Total Ciliate Populations in Arable Soil Amended with Wheat

Soil protozoa are characterized by their ability to produce cysts, which allows them to survive unfavorable conditions (e.g., desiccation) for extended periods. Under favorable conditions, they may rapidly excyst and begin feeding, but even under optimal conditions, a large proportion of the population may be encysted. The factors governing the dynamics of active and encysted cells in the soil are not well understood. Our objective was to determine the dynamics of active and encysted populations of ciliates during the decomposition of freshly added organic material. We monitored, in soil microcosms, the active and total populations of ciliates, their potential prey (bacteria and small protozoa), their potential competitors (amoebae, flagellates, and nematodes), and their potential predators (nematodes). We sampled with short time intervals (2 to 6 days) and generated a data set, suitable for mathematical modeling. Following the addition of fresh organic material, bacterial numbers increased more than 1,400-fold. There was a temporary increase in the number of active ciliates, followed by a rapid decline, although the size of the bacterial prey populations remained high. During this initial burst of ciliate growth, the population of cystic ciliates increased 100-fold. We suggest that internal population regulation is the major factor governing ciliate encystment and that the rate of encystment depends on ciliate density. This model provides a quantitative explanation of ciliatostasis and can explain why protozoan growth in soil is less than that in aquatic systems. Internally governed encystment may be an essential adaptation to an unpredictable environment in which individual protozoa cannot predict when the soil will dry out and will survive desiccation only if they have encysted in time.     

Distribution and diversity of soil protozoa in the McMurdo Dry Valleys of Antarctica

The polar desert soils of the McMurdo Dry Valley region support a limited water film community dominated by flagellates, amoebae, and nematodes. This study describes the protozoa and compares their distribution to nematodes. In 50 samples collected from 12 locations, rotifers and tardigrades were infrequent, and ciliates and testacea were rare. Soil protozoa occurred at all sites but the dominant nematode, Scottnema lindsayae (Timm 1971), did not, indicating soil habitat factors limiting nematode distribution are not limiting to protozoa. In contrast to the nematode species, which are all endemic to Antarctica, there were no endemic protozoan morphospecies found in our samples. The protozoan abundance was several orders of magnitude greater than that of the nematodes, and the species diversity was much greater. Most of the protozoa grew better at lower incubation temperatures. The ubiquitous distribution of protozoa suggests their importance in soil food webs and nutrient cycling in the dry valleys.     

Population dynamics of active and total ciliate populations in arable soil amended with wheat

Soil protozoa are characterized by their ability to produce cysts, which allows them to survive unfavorable conditions (e.g., desiccation) for extended periods. Under favorable conditions, they may rapidly excyst and begin feeding, but even under optimal conditions, a large proportion of the population may be encysted. The factors governing the dynamics of active and encysted cells in the soil are not well understood. Our objective was to determine the dynamics of active and encysted populations of ciliates during the decomposition of freshly added organic material. We monitored, in soil microcosms, the active and total populations of ciliates, their potential prey (bacteria and small protozoa), their potential competitors (amoebae, flagellates, and nematodes), and their potential predators (nematodes). We sampled with short time intervals (2 to 6 days) and generated a data set, suitable for mathematical modeling. Following the addition of fresh organic material, bacterial numbers increased more than 1,400-fold. There was a temporary increase in the number of active ciliates, followed by a rapid decline, although the size of the bacterial prey populations remained high. During this initial burst of ciliate growth, the population of cystic ciliates increased 100-fold. We suggest that internal population regulation is the major factor governing ciliate encystment and that the rate of encystment depends on ciliate density. This model provides a quantitative explanation of ciliatostasis and can explain why protozoan growth in soil is less than that in aquatic systems. Internally governed encystment may be an essential adaptation to an unpredictable environment in which individual protozoa cannot predict when the soil will dry out and will survive desiccation only if they have encysted in time.