外来种紫茎泽兰对入侵地土壤动物群落及多样性的影响

在云南省澜沧县对草地、以紫茎泽兰群落以及次生林地中的土壤动物一步甲和蚯蚓群落进行动态取样调查，来探讨紫茎泽兰入侵后对群落结构、生物多样性的影响。 在紫茎泽兰和草地群落中共捕获2253头步甲，35个种，其中草地上捕获1574头步甲，28个种，紫茎泽兰样地中有679头步甲，34个种;紫茎泽兰群落中步甲个体数量少，但物种数多，多样性也比较高;草地中步甲优势物种为Harpalus indicus和Tetragonoderus arcuatus占总数的59％;而紫茎泽兰中的优势物种比较分散;紫茎泽兰群落中步甲个体体型较大，而草地中体型小的步甲所占比例较高;步甲分布与落叶层厚度、土壤全磷含量、植被高度、地上生物量及土壤pH和土壤全钾含量有一定的相关性;紫茎泽兰群落与草地中的指示物种也不同，Hyphaereon masumotoi和Cosmodiscus sp．是紫茎泽兰的指示物种，而草地的指示物种有Aephnidius adelioides，Tetragonoderus arcuatus，Harpalus indicus，Harpaliscus birmanicus，Chlaenius cambodiensi。 受紫茎泽兰入侵的林地边缘步甲群落的分布规律表明，步甲个体数量排序：林地内部>紫茎泽兰群落>林地边缘：三者步甲优势种的组成，既有交叉也有区别;三者的步甲物种数及多样性指数差异不显著，步甲群落的时间动态也相似;林地边缘、内部及紫茎泽兰群落在步甲个体体型结构上差异不大，具有指示作用的步甲种少。 在草地、紫茎泽兰及次生林地三种植被类型中，共采集到3546条蚯蚓，8个种。其中，紫茎泽兰群落有1663条蚯蚓，远高于次生林及草地。多裂远盲蚓和娇小远盲蚓是当地蚯蚓群落的优势种;紫茎泽兰入侵地的蚯蚓物种数、Shannon-Wiener多样性指数大于草地及次生林地;蚯蚓数量及生物量的时间动态受月份降雨量的影响很大，体型大小不同的蚯蚓受降雨变化影响的程度不同：蚯蚓的分布与落叶层厚度、土壤全氮含量、土壤pH及有机质含量相关性较强;蚯蚓群落中只有大唇远盲蚓是紫茎泽兰样地中的指示物种。 在紫茎泽兰控制实验样地内，步甲的数量及物种数的排序是原始紫茎泽兰>半密度紫茎泽兰>去除处理。优势物种都为Anisodactylus karennius，所占比例高，其在原始紫茎泽兰群落中的分布数量远高于半密度及去除样地;步甲群落多样性指数(H’)和物种数差异不显著;三种处理的步甲群落时间动态不同，表现出不同的高峰期;Galeritula feoe和Nanodiodes piceus是原始和半密度紫茎泽兰样地中的指示物种。 总之，紫茎泽兰入侵相对单一草地后，会引起步甲个体数量下降，物种数和多样性上升，群落结构发生很大变化;紫茎泽兰入侵的林地边缘及外部草地后，林地边缘的环境变化幅度减小，林地的边际效应趋于不明显;紫茎泽兰单优群落有利于蚯蚓生存于生活，与草地及林地相比，能增加蚯蚓鲜重及多样性水平。

老秃顶子自然保护区北坡森林土壤动物多样性研究

土壤动物区系是分解者食物网的重要组成部分，在分解作用、养分循环和土壤肥力保持中起重要的作用。论文以辽宁老秃顶子北坡森林生态系统为研究对象，综合运用野外调查、室内分析和多元统计方法，对土壤动物组成和多样性随海拔梯度变化（海拔>700m）、典型天然次生林土壤动物组成与多样性（海拔<700m）、典型人工林土壤动物群落组成和多样性等问题进行定量分析研究，旨在揭示土壤动物生态分布规律，为生态系统生物多样性保护和恢复提供数据支持。 研究结果表明：（1）采集的主要土壤动物隶属于7门、11纲、18个目，其中蜱螨4亚目、41科，中气门亚目26个属；土壤动物类群数量与密度的对数值呈极显著线性正相关关系。（2）无论是天然林，还是人工林，不同林型间大型土壤动物密度和组成有显著差异，除天然赤松林外，其他样地蜱螨密度、多样性指数差异多不显著；（3）各海拔群落间土壤动物密度随海拔梯度的升高呈现先下降后升高、之后又下降的趋势；（4）不同海拔高度，相邻群落螨类共有度高，低海拔相邻群落共有度大于高海拔相邻群落螨类共有度（5）天然林大型土壤动物优势类群多为腹足纲、后孔寡毛目（蚯蚓）和膜翅目；人工林大型土壤动物优势类群为膜翅目；无论天然林群落还是人工林群落，奥甲螨科均为螨类优势类群。（6）土壤动物群落沿海拔的垂直分布可划分为：海拔<1100m的低海拔土壤类群带和海拔>1100m的高海拔土壤动物类群；（7）典型天然次生林（海拔<700m）土壤动物群落可划分为阔叶林土壤动物群落、天然油松林土壤动物群落、天然赤松林土壤动物群落。（8）植被类型、乔木多样性和坡向是影响土壤动物组成和分布的重要因素。

辽东山区次生林生态系统土壤动物多样性研究

土壤动物作为生态系统中重要的组成部分，在陆地生态系统中的物质循环、凋落物的分解以及土壤肥力保持中起着重要的调节作用。论文以辽东山区次生林生态系统中土壤动物为研究对象，旨在揭示土壤动物生态分布规律，为次生林生态系统的研究和可持续发展提供理论依据，为清原站积累数据。 本文综合野外调查、室内分析和统计，对不同林型、不同龄级落叶松人工林、不同干扰程度对土壤动物种类组成和动态的影响以及干扰对土壤线虫的群落结构的影响等问题进行分析研究， 研究结果表明：（1）共获取土壤动物3门、8纲、32目；线虫49属。优势类群为弹尾目与真螨目。（2）天然林比人工林具有稳定的生态环境，大中型土壤动物群落在生长季中波动范围小，凋落物本身理化性质和凋落物分解过程产生的不同微生物，导致了土壤动物类群的差异性；（3）27a落叶松人工林大中型土壤动物多样性与生物量高于9a落叶人工林与43a落叶松人工林，其原因可能是光照、温度、湿度，落叶松人工林的毒化作用等；（4）干扰改变了大中型土壤动物群落的种类组成，同时随着干扰度的增加，土壤动物的类群数与个体数减少。土壤动物多样性从小到大排序为：裸地土壤动物 < 人工林土壤动物< 次生林土壤动物；（5）干扰改变了线虫群落的种类组成，同时随着干扰度的增加，线虫的多样性减少，影响土壤线虫的主要原因有土壤养分，立地条件，地区不同光照所致等。

杉木人工林土壤动物群落特征

土壤动物在森林生态系统中起着非常重要的作用，但杉木人工林土壤动物的研究尚属空白。传统的杉木（Cunninghamia lanceoata）用材林经营易导致土壤退化，降低土壤的生产潜能。目前许多造林学家正在植物群落水平上应用不同的栽植模式调节土壤系统以改善杉木人工林采伐迹地的土壤质量。本文的目的是为了确定这种调节方式如何影响土壤动物群落的多度、多样性和生物量格局。此项研究选择了立地条件非常相似的3种栽植模式。20年生的一、二代杉木纯林以天然次生常绿阔叶林为对照构成连栽组；13年生8杉木2桤木（AInus creemstoyne）混交林以13年生二代杉木纯林为对照，20年生8杉木2火力楠（越动eI勿朋cc了盯创）混交林以20年生二代杉木纯林为对照组成两种混交模式；20年生火力楠纯林以20年生二代杉木纯林为对照构成轮栽组。同时在第一代杉木纯林中抽取了5块样地监测群落的季节变化作为一种辅助性的调查，结果表明：在多度上，杉木人工林取代天然林后，土壤动物出现了显著性的下降，但是一二代杉木纯林之间没有明显的差别，火力楠轮栽主要促进了大型土壤动物的增加，但火力楠混交对土壤动物没有影响，恺木混交主要促进了双翅目、(虫+齿)目、线虫、线蚓的增加。在多样性上，一、二代杉木之间连栽对土壤动物没有影响，但杉木人工林取代天然林、火力楠混交、火力楠轮栽以及恺木混交均显著地降低了土壤动物的多样性。在生物量上，各对比林型之间均没有发现显著性的差别。从目前的观察看来，多度和多样性的结果支持树种是驱动土壤动物群落发展的一个主要原因，生物量的结果表明栽植模式对土壤动物的影响在某些方面是有限的，也暗示应用栽植模式来调控土壤质量是一个长期的过程。

The thermo-visco-plastic instability analysis of saturated soil

A theoretical analysis of instability of saturated soil is presented considering the simple shearing of a heat conducting thermo-visco-plastic material. It is shown that the instability is mainly the consequence of thermal softening which overcomes the strain hardening and the other type of instability is controlled by strain softening. The effects of other factors such as permeability to the instability are discussed in this paper.

On the shear instability of saturated soil

In this paper. the dynamic instability of simple shear of saturated soil is discussed. The governing equations are obtained based on mixture theory in which the inertia effect and the compressibility of grains are considered. Perturbation method is used to analyze and it is shown that two types of instability may exist. One of them is dominated by pore-pressure-softening, while the other by strain-softening.

An Analytical Solution for Three-Dimensional Diffraction of Plane P-Waves by a Hemispherical Alluvial Valley with Saturated Soil Deposits

An analytical solution for the three-dimensional scattering and diffraction of plane P-waves by a hemispherical alluvial valley with saturated soil deposits is developed by employing Fourier-Bessel series expansion technique. Unlike previous studies, in which the saturated soil deposits were simulated with the single-phase elastic theory, in this paper, they are simulated with Biot's dynamic theory for saturated porous media, and the half space is assumed as a single-phase elastic medium. The effects of the dimensionless frequency, the incidence angle of P-wave and the porosity of soil deposits on the surface displacement magnifications of the hemispherical alluvial valley are investigated. Numerical results show that the existence of a saturated hemispherical alluvial valley has much influence on the surface displacement magnifications. It is more reasonable to simulate soil deposits with Biot's dynamic theory when evaluating the displacement responses of a hemispherical alluvial valley with an incidence of P-waves.

Comparison of the Dynamic Response of a Saturated Soil Between Two Models

By comparing the dynamic responses of saturated soil to Biot's and Yamamoto's models, the properties of the two models have be pointed out. First of all, an analysis has been made for energy loss of each model from the basic equations. Then the damping of elastic waves in coarse sand and fine sand with loading frequency and soil's parameters have been calculated and the representation of viscous friction and Coulomb friction in the two models has been concluded. Finally, the variations of loading wave damping and stress phase angles with water depth and soil's parameters have been obtained as loading waves range in ocean waves.

Numerical Study on Rainfall Infiltration in Rock-Soil Blocks

A mathematical model for the rain infiltration in the rock-soil slop has been established and solved by using the finite element method. The unsteady water infiltrating process has been simulated to get water content both in the homogeneous and heterogeneous media. The simulated results show that the rock blocks in the rock-soil slop can cause the wetting front moving fast. If the rain intensity is increased, the saturated region will be formed quickly while other conditions are the same. If the rain intensity keeps a constant, it is possible to accelerate the generation of the saturated region by properly increasing the vertical filtration rate of the rock-soil slop. However, if the vertical filtration rate is so far greater than the rain intensity, it will be difficult to form the saturated region in the rock-soil slop. The numerical method was verified by comparing the calculation results with the field test data.

土壤传热特性的实验研究(Experimental Study of Soil Heat Diffusivity)

发展了测定实验室土样热扩散率的方法,介绍了研制的实验装置和建议的操作程序。给出的实验结果表明土壤热扩散率随土壤空隙率、含水量和温度等许多参数而变化。

The evolution of shear bands of saturated soil

The development of the shear bands of saturated soil in coupling-rate- and pore-pressure-dependent simple shear has been discussed, using a simple model and a matching technique at the moving boundary of a shear band. Tt is shown that the development of shear bands are dominated by the coupling-rate and pore-pressure effect of the material. The strength of the soil acts as a destabilizer, whilst pore pressure diffusion makes the band expand. The theory is discussed and some computational solutions have been presented.

Wave-soil-pipe coupling effect on submarine pipeline on-bottom stability

Wave-soil-pipe coupling effect on the untrenched pipeline stability on sands is for the first time investigated experimentally. Tests are conducted in the U-shaped water tunnel, which generates an oscillatory how, simulating the water particle movements with periodically changing direction under the wave action. Characteristic times and phases during the instability process are revealed. Linear relationship between Froude number and non-dimensional pipe weight is obtained. Effects of initial embedment and loading history are observed. Test results between the wavesoil-pipe interaction and pipe-soil interaction under cyclic mechanical loading are compared. The mechanism is briefly discussed. For applying in the practical design, more extensive and systematic investigations are needed.

Experimental study on pore pressure in rock-soil slope during reservoir water level fluctuation

A test system was developed for measuring the pore pressure in porous media, and a new model was devised for the pore pressure testing in both saturated and unsaturated rock-soil. Laboratory experiments were carried out to determine the pore pressure during water level fluctuation. The variations of transient pore pressure vs. time at different locations of the simulated rock-soil system were acquired and processed, and meanwhile the deformation and failure of the model are observed. The experiment results show that whether the porous media are saturated or not, the transient pore pressure is mainly dependent on the water level fluctuation, and coupled with the variation of the stress field.