土壤生态PPT整理 新(2)

? Limitations of molecular-based methods: Lyses efficiency of cells or fungal structures varies between and within microbial groups; The method of DNA or RNA extraction used can also bias diversity studies; With environmental samples, it is necessary to remove inhibitory substances such as humic acids and clay.

? Taxonomic ambiguity of microbes: The traditional species definition was based on higher plants and animals and does not readily apply to prokaryotesor asexual organisms.

How to measure soil microbial diversity? 生物化学方法:

Culture-dependent methods

? Dilution plating and culturing methods

? Researchers assessed the gross diversity of culturable microorganisms by plotting the different colonies identified on the medium against the incubation time. Because a limited number of microorganisms can be cultured and the procedures are laborious, this method is less popular.

Indeed, it is available and useful especially at the beginning of study! ? Community-level physiological profiles（CLPP or SCU) Biolog method has as many disadvantages as advantages

1) First, the density of the initial inocculum;2) Functional diversity assumption is based on utilizing a particular substrate;3) Ecologically relevant.

Culture-independent methods

? This method provides information on the microbial community composition based on groupings of fatty acids, fatty acid methyl ester (FAME), Phospholipid fatty acid (PLFA) analysis.

? Phospholipid fatty acids are potentially useful signature molecules due to their presence in all living cells.

? An essential consideration in the use of these molecules to describe microbial communities is that unique fatty acids are indicative of specific groups of organisms.

Phospholipid fatty acid (PLFA) analysis

The presence and abundance of these signature fatty acids in soil reveals the

presence and abundance of particular organisms or groups of organisms. How to measure soil microbial diversity? 分子生物学方法

? A number of approaches have been developed to study molecular microbial diversity.

? DNA reassociation, DNA–DNA and mRNA/DNA hybridization, DNA cloning and sequencing;

? Other PCR-based methods such as denaturing gradient gel electrophoresis (DGGE), temperature gradient gel electrophoresis (TGGE), ribosomal intergenic spacer analysis (RISA) and automated ribosomal intergenic space analysis (ARISA), Terminal restriction fragment length polymorphism (T-RFLP).

微生物多样性与功能

? 土壤微生物多样性的重要作用是维持土壤功能的正常，而 有机物的分解和养分循环是最重要的功能。

? The relationship between microbial diversity and function in soil is largely unknown, and soil seems to be characterized by a redundancy of functions; but biodiversity has been assumed to influence ecosystem stability, productivity and resilience towards stress and disturbance. Functional diversity is an aspect of the overall microbial diversity in soil, and encompasses a range of activities. 微生物群落功能多样性研究方法

实际上，功能多样性比分类多样性对土壤生 态系统研究更重要，是首要关注方面。 I. 群落代谢指纹II. 碳源利用反应（群落代谢） III.典型土壤过程IV. 酶功能多样性I. 群落代谢图谱

? BIOLOG is nowadays much in favor to measure microbial (especially for bacterial) functional diversity in soil because the utilization of available carbon is the key factor governing microbial growth in soil.

? 群落代谢图谱(CLPP), 也称作单一碳源利用模式（SCU) 最大的缺陷与传统培养法相似，即短时间的、非原位的（土壤提取液）和培养的（添加了底 物）；

? 至今，有很多原理相似的改进方法出现，但由于操作 上的原因还没有被广泛应用，例如??

II. 碳源利用反应

? Campbell et al.(2003) developed a MicroRespTM approach.? This

approach allows for the rapid assessment of CLPP from whole soils using a colourmetric detection system (cresol red) and an automated plate reader.? Recently, a paper compared two approaches Biolog and MicroRespTM said the MicroRespTM was much better (Lalor et al. 2006). Campbell, C. et al. 2003. A rapid microtiter plate method to measure carbon dioxide evolved from carbon substrate amendments so as to determine the physiological profiles of soil microbial communities by using whole soil. AEM 69, 3593–3599.

丰富多彩的土壤生物 土壤生物的重要价值

? Soil organisms are extremely diverse and contribute

to a wide range of ecosystem services that are essential to the sustainable function of natural and managed ecosystems (Barrios, 2007).? The vast array of soil organisms constitute the soil food web, had direct and indirect impacts on land productivity and soil process.

? The lack of information of soil organisms is surprising, considering the majority of the Earth’s species might live in soil (Wardle, 2002). 1.1 土壤生物－组成

? 土壤生物包括植物的地下部分 (Roots)，藻类 (Algae)、微 生物 (Microflora) 和土壤动物 (Soil fauna/Soil animal);? Living Organisms in Soil:

Microflora (virus, bacteria and fungi), Green plant (roots and algae); Fauna: protozoa, nematode, rotifera, Tardigrada, Oligochaeta (earthworms and enchytraeid), Mollusca (snail and slug), Arthropoda (spider, collembola, mite, woodlice, millepede).

?植物和土壤生物种类数量的估计 (modified from Wall et al., 2001) ?土壤生物数量和生物量比较

类群Group密度Ind. m-2生物量Biomass m-2

原生动物 Protozoa 109-1011 6-30+ 线虫 Nematode 106-30*106 1-30 蚯蚓 Earthworm 50-400 20-400 螨类 Acari 2*104-40*104 0.2-4 弹尾虫 Collembola 2*104-40*104 0.2-4 昆虫幼虫 Insect Larva >500 4.5 多足类 Myriapoda倍足纲 Diplopod 20-700 0.5-12.5 唇足纲 Chilopod 100-400 1-10 等足类 Isopoda >1800 >4 1. 2 土壤生物－结构 营养结构/功能群分类

? 植食者或寄生者 (herbivore, parasites or disease)

? 共生互利者 (microsymbiont)? 初级消费者－分解者(decomposer or transformer)? 次级消费者－食微者 (microbiovore)? 捕食者(predator)? “生态工程师” (ecosystem engineer) 2. 土壤 (无脊椎) 动物多样性

? The other last biotic frontier-Soil Fauna/Soil Animal！ 2.1 土壤动物分类－定义

? Soil Fauna: Animals that live temporarily or permanently in the soil, at its surface or in its annexes； ? Do you know soil a 2.1 土壤动物分类－类群

? Taxonomic (分类学的): See slides before.

? Functional group (功能群): Group species close to each other occupying similar ecosystem functions.

? Soil fauna may be characterized by size, morphological adaptations, mode of movement, water relations, microhabitats, duration in soil, stratification ?? 2.1 土壤动物分类－类群 ——Body Size(个体大小)

? The approach to ecological niche by size of soil fauna is very informative.

1) Many ecological functions depend on size;

2) Body size(width) is related to their microhabitats.

? Generally, soil fauna is divided into three size categories: 1) <0.2mm, microfauna, 2) 0.2-10mm, mesofauna, 3) >10mm macrofauna (Note: it’s length). ? Or body width: 1) <0.1mm, microfauna, 2) 0.1-2.0mm, mesofauna, 3) >2mm macrofauna (Note: it’s diameter). 2.2 土壤动物功能

? Soil invertebrate fauna are key mediators of soil function? The

comminution and incorporation of litter into soil, the building and maintenance of structural porosity and aggregation in soils through burrowing, casting and nesting activities, the control of microbial communities and activities, plant protection against some pests and diseases, acceleration of plant successions are among the many effects they have on other organisms through their activities.? The hierarchical contributions of soil fauna activities to soil functions were reflected at large scales, such as water supply/soil erosion, nutrient cycling, primary production, soil formation and climate regulation. Lavelle et al. 2006 2.2 土壤动物功能

? Water supply/soil erosion mainly through? building and maintenance

of stable porosity through bioturbation and burrowing? production of stable biogenic aggregates through casting and organic matter transformation process? modification of soil structure and biophysical properties through plant/roots, microbes and other soil properties. For example, earthworm influence soil aggregate formation? Lavelle et al. 2006 2.2 土壤动物功能

? Nutrient cycling mainly through? instantaneous enhancement of mineralization and humification of organic substrates by comminution of litter.? selective activation of microbial activities through microbe feeding, exudation and dispersal activities.? carbon and nutrient sequestration in microsites (i.e. rhizosphere, detritusphere, aggregatushere) through biogenic structure.? regulation of nutrient losses (leaching/denitrification)

through biogenic structure, effects of plant/roots. 2.2 土壤动物功能

? Enhanced primary production mainly through

? stimulation of symbiotic activity (mycorrhizae and N-fixing microorganisms) and control of pests/diseases above- and belowground through biological interactions in soil and enhancement of plant vigor.? Enhanced nutrient release and plant uptake by positive effects on water supply, nutrient cycling and soil structure.? indirect production of molecules (hormone-like effect) on plant/roots by invertebrates and microorganisms. 2.2 土壤动物功能

? Soil formation (pedogenesis process) mainly through

? biogenic modification soil structure/texture by bioturbation, surface deposition and particle selection.

? accumulation effects of soil fauna on soil physical, chemical and biological process at different shorter scales of time and space.

? the roles of soil fauna in pedogenesis process depend on many factors at different temporal and spatial scales? Lavelle et al. 2006 2.2 土壤动物功能

? Climate regulation mainly through

? consumption/production of greenhouse gases through organic matter sequestration in stable aggregates and resource properties modification in hot microsites.

? organic matter storage in soil and biomass by enhanced formation of recalcitrant organic compounds.

? regulation of organic carbon stability through the accumulation over large periods of time of small-scale effects of plant/roots, microbial community and other soil properties. Lavelle et al. 2006 2.3 土壤动物研究方法

? 研究方法和技术是制约土壤生物，特别是土壤 动物研究的重要因素；

? 虽然新技术的出现促进了土壤生物研究的发展 的，但是传统方法仍然具有不可替代的作用；

? 典型土壤动物的研究方法（节肢动物、 线虫和原生动物）将在实验课前夕单独 讲授。

3. 土壤无脊椎动物类群简介

? 原生动物? 线虫? 轮虫和熊虫? 弹尾虫和螨类? 线蚓? 蚯蚓? 蚂蚁? 白蚁? 描述? 分类，数量，生理，生境? 时空分布? 功能 3.1 原生动物

? Taxonomic classification: All the protozoa are grouped in the kingdom of Protista. Subkingdom Protozoa. 11 classes, of which 3 are important in soil: Zooflagellata, Rhizopoa (naked Amoebae and Testacea), Cillata. ? Morphological characteristics: Unicellular eukaryotes. ? Size of species: Microfauna, from 3 to 250um (possible <100um);

? Number of species: Nearly 50,000 known; exhibit a hidden diversity’ (Foissner et al., 2002).

? Microhabitat: Interstitial soil water and film water on the surface of the microaggregates and their growth rate or distribution is limited by pore-size distribution. 原生动物

Some common protozoa.

r-Selected species are on the left (and for ciliates and testacea) and K-selected species on the right (Bamforth, 1997, p67) Ciliate(Colpoda maupasi) of different photomicrographs Huws et al.2005.Journal of Applied Microbiology, 98, 238 3.1 原生动物

? Life mode: Free-living, but parasitic and symbiotic soil species exist. Cysts are resistant dispersal forms.

? Feeding regimes: Bacteriophagous, saprophagous, predators. ? Abundance: Except the bacteria, these are the most abundant organisms in soil. Estimates is 107-109 ind. m-2 .

? Metabolic rate and life history: Growth maybe rapid under favorable conditions, with generation time varies from two to 48 hours. Protozoa have high energy conversion efficiency, spending little energy on location and maintenance and investing most energy into making macromolecules(growth). They show distinct r- and K strategies. ? Water relations and stress: Water is a major determinant of protist life. True resistant cysts may withstand extreme conditions of exposure to drought, temperature or acidity. 3.2 线 虫

? Taxonomy: Nematodes are filiform Metazoa. The phylum Nematoda comprises 2 classes, 20 orders and nearly 200 families. 20,000 known, may be over 100,000.

? Size: Free living soil nematodes are small (0.15-5mm long and 2- 100um side with individual weights of 20-60ng).

? Metabolic & Reproduction: Respiratory rate is high(Nielsen,1949). The length of development period is influenced by temperature. Reproduction is either amphimictic(两性) or parthenogenetic (单性生殖). Nematodes produce eggs in ca. 20 days (5 to 50). ?Habitat: Nematodes are aquatic animals living in film and interstitial water, rhizosphere and decomposing material.

? Feeding regimes: Microphagous, phytophagous, carnivorous? Bacterial feeders may ingest up to 5000 cells per minute or 6.5 times their own weight per day.

Head structure of some nematodes and trophic level Freckman. 1982. Nematodes in Soil Ecosystem. p55 抗胁迫能力

Examples of nematode survival after lengthy time in anhydrobiosis McSorley. 2003. Florida Entomologist 86: 138

Nematode tolerance to desiccation after preconditioning

Scanning electron micrographs of desiccated Panagrolaimus following exposure to dried silica gel (<10% RH; relative humidity) for 48?h. (A) Panagrolaimus superbus exposed directly to silica gel without preconditioning; (B) Panagrolaimus sp. PS1159, (C) Panagrolaimus sp. BW287 , (D) Panagrolaimus sp. PS1732 exposed to silica gel following preconditioning at 98%

RH for 72?h. Scale bars, 15μm (A–C), 10μm (D). 3.2 线 虫

? Abundance:? Nematode are the most abundant animals in soil after protozoes.Density ranged from 100 to 1,000 individuals per gram soil. Or 1 to 30 million ind. m-2 (=biomass of 1-30g m-2 ).? Relatively high densities have been recorded in extreme environments.? Main variables influencing abundance are the soil hydrological regimes and the content of organic matter on the soil surface.? Community structure:? Species: Very rich.

? Feeding habits or functional structure:

Diverse, i.e. bacterial feeders, fungal feeders, root feeders, predators and omnivores.

3.3 轮虫 (轮形动物门Phylum Rotifera)

3.3 轮虫? Taxonomy: Rotifera is divided into two classes, the Digononta (双巢纲) and the Monogononta (单巢纲). The Digononta class is divided in two orders: Bdelloidea (蛭态轮虫目) and Seisonidae (marine 摇轮虫目 ).? Morphology and Size: The name rotifer is from Latin meaning \bearer\The two wheels on rotifers are made of cilia that beat and create a current that draws water containing food into the gut of the rotifer. They are about the same size (range between 50μm and 2000 μm) as the larger unicellular organisms.

? Movement: They locomote by using the crown of cilia (纤毛) to propel themselves. Some species walk with head and foot. Their foot can secrete a sticky substance that enables them to attach to a surface. 3.3 轮虫生态功能

? 轮虫因其极快的繁殖速率，生产量很高，在生态系结构、功能和生物生产力 的研究中具有重要意义。

? Mineralization of N immobilized in bacterial biomass. May be responsible for up to 50% or more of plant N available in certain agricultural systems. Soil conditions must be appropriate for rotifers to be active, requiring moist-to- saturated soil.? Substrate for predators (nematodes, rotifers,

earthworms, enchytraeids)?Consumption of bacterial prey and control of bacterial community structure.

? 轮虫也是一类指示生物，在环境监测和生态毒理研究中被普遍采用。? While numbers and species of bacteria can be controlled by protozoa, little work has been done with rotifer-bacteria interactions in soil systems. Rotifers do play important roles in aquatic systems, but are un-studied in terrestrial systems. Most likely, they would play an important role in riparian soils.

Ingham E. R. 1995. Soil organisms: bacteria, fungi, protozoa, nematodes and rotifers. 93p

3.4 熊虫 (缓步动物门)

? Taxonomy: The phylum Tardigrada belongs to the Panarthropoda group, together with the onychophorans (velvet worms) and arthropods, and comprises almost 1,000 described species. However, taxonomists expect that at least 10,000 species exist. Tardigrada exhibit a mixture of the features of arthropods(节肢动物) and annelids (环节动物). Recently,molecular phylogenetic analysis suggested that tardigrades are related to both ? 在土壤微结构(microstructure)的形成中占有重要地位 (Rusek, 1998).? 微型节肢动物灵敏响应环境变化(Rusek, 1998)，也是很好的土壤生态系统指示者

2.6 线 蚓

线蚓对凋落物叶分解的作用

? 土壤切片的微形态显微观察 ? 土壤培养中的线蚓和螨类 土壤线蚓生态功能

? 促进或抑制有机物分解和养分矿化 ? 直接和间接影响植物生长? 线蚓取食微生物可以提高微生物活性和周转，改变微生物群落结构 ? 传播和促进(抑制)土壤微生物定殖；? 在土壤微结构 (孔隙和微团聚体)的形成和稳定中占有重要地位，可能影响土 壤有机碳的稳定性 (Fox et al. 2006 )；? 微型节肢动物是联接土壤食物网的关键环节;

? 环境指示者 (Rombke, 2003)。 蚯蚓功能群分类 微生物量碳测定

氯仿熏蒸 12.5g鲜土于铝盒中 25ml无醇氯仿 小纸片于小烧杯 抽真空使氯仿沸腾5min，关紧活塞。置于阴暗处，250C熏蒸24h。24h后，取出小烧杯后反复抽真空nematodes and arthropods in a new grouping, the \(moulting animals) (Aguinaldo, et al. 1997).

? Size: These little interesting micrometazoans, ranging from 50μm to 1200μm, are also called water bears(bear worm 熊虫).? Habitat and abundance: They live mainly in mosses and film water of soil. The density in soil is 10,000 to 200,000 ind. m-2 . Tardigrades tend to occur in the surface 1-2 cm of many soils. They may serve as sensitive indicator for environmental stress.

据称：动物学家公认熊虫是生命力 最强的动物。 Cryptobiosis

? Tardigrades are known to survive long periods of drying or freezing by cryptobiosis (隐生现象).

Very regular, symmetric tun of an eutardigrade water bear formed after slow desiccation. Length ca. 0.2 mm.

? 当环境恶化时，缓步类动物会把身体蜷缩起来，一动不动。这时。它们会放弃体内99%的水分，进入一种假死状态。当体温降低到一定程度时，这种动物会缩小身体，收回所有的腿，关闭体内的所有系统，直到环境改善为止。缓步类动物不仅能在零下200度的寒冷环境中生存，就是在151度的酷热环境中，同样可以保住自己的生命。它还可以在沙漠中生存，在耐旱能力方面，就连骆驼也比不过缓步类动物。在很久以前，曾有一只缓步类动物，被困在一家博物馆干燥的苔藓标本中。120年后，当科学家在苔藓中加水时，它竟然又复活了。这种动物的耐力不仅体现在地球上，它们还能在太空的真空中生活。

Trace different phases of Tardigrades rehydration All of rehydration phases are finished after about 10 to 15 minutes. The series of photos below shows the revival of a tardigrade of the Macrobiotus hufelandi group. The initial size of tun is 0.3 mm. 3.4 熊虫生态功能

? 熊虫在土壤生态系结构和功能中的意义仍基本属于未知领域。? Today, researchers think that tardigrades could be used as test animals for traveling into outer space.? 熊虫也是一类实验模式生物，在分子生物学和生物进化研究上将具有 强大优势。? The pharmaceutical industry has been very interested in role of the sugar trehalose (海藻糖) that tardigrades produce prior to anhydrobiosis and cryobiosis stages. Trehalose appears to protect the cellular membranes of tardigrades against damage from freezing and dehydration.

微型节肢动物 (microarthropod)

微型节肢动物主要包括弹尾虫 (collembolans) 和螨类 (mites) ， 二者在个体大小上属于中型土壤动物。 3.5 弹尾虫 3.6 螨 类

? mites We can see some movies in Google Enchytraeid and mite 甲 螨 (Oribatei)直卷甲螨 懒甲螨 大翼甲螨 中气门螨 (Mesostigmata) ? Mesostigmatic mites are not as numerous as oribatids or prostigmatic mites, but are universally present in soils and may be important predators-Nematodes and Collembola. 微型节肢动物生态功能

? 微型节肢动物是土壤生物多样性的重要组分，强烈影响 (尤其森林生态系统)分解过程(Santos and Whitford, 1981)和养分矿化;? 微型土壤动物影响直接和间接影响植物生长 (Gange, 2000);? 微型节肢动物能够传播微生物，通过取食提高微生物活性和周转，影响菌丝 形态和酶产量 (Bretherton et al, 2006)，并直接和间接改变微生物群落结构 和多样性；? 微型节肢动物是联接土壤食物网的关键环节. Many microarghropods feed

on fungi and nematodes, thereby linking the microfauna and microbes with mesofauna. In turn, microarthropods are prey for macroarthropods, thus bridging a connection to the macrofauna；

2~3次（每次5分钟），排除氯仿100ml塑料瓶50ml 0.5M K2SO4 器测定溶液中的DOC 含量振荡30min，过滤取8-10ml滤液

直接用TOC仪

百度搜索“77cn”或“免费范文网”即可找到本站免费阅读全部范文。收藏本站方便下次阅读，免费范文网，提供经典小说综合文库土壤生态PPT整理 新(2)在线全文阅读。