Seasonal abundance and diversity of spiders in two intertidal marsh plant communities

The spiders of two Mississippi marsh communities were studied from January 1982 through March 1983. Monthly collections were made in two adjacent marsh plant zones dominated bySpartina cynosuroides (L.) Roth andJuncus roemerianus Scheele respectively. A total of 38 species of spiders (36 inSpartina, 33 inJuncus) representing 13 families were collected. The dominant species in theSpartina zone includedPirata mayaca Gertsch,Lycosa watsoni Gertsch (Lycosidae),Clubiona saltitans Emerton,Scotinella formica (Banks) (Clubionidae),Floricormus sp. (Linyphiidae),Dictyna sylvania Chamberlin & Ivie (Dictynidae),Paramaevia hobbsae (Barnes) (Salticidae), andAgelenopsis barrowsi Gertsch (Agelenidae). The dominant species in theJuncus zone includedLycosa watsoni, Pirata mayaca, Clubiona saltitans andSarinda hentzi (Banks) (Salticidae). Density, biomass, species richness and equitability peaked in May in theJuncus zone and in June in theSpartina zone. Peak levels of density and biomass corresponded to the reproductive activity of the common species, while diversity patterns were attributable to the reproductive activity of the less common species. Mean values of density and biomass over the study period were 84.8 spiders per m² and 155.6 mg per m² in theSpartina zone and 39.4 spiders per m² and 133.0 mg per m² inJuncus zone. The Juncus zone was flooded more frequently, contained less litter, and supported lower overall density and diversity of spiders.     

Estimating species diversity: Comparison of two algorithms

Two approaches to estimating the number of species in a lithologic unit are compared. An empirical model of the sampling process, which involves fitting the equation of a rectangular hyperbola to the data from a collector's curve, is compared with a logarithmic model derived from a statistical theory of sampling. The two approaches give equally accurate estimates of species richness when organisms are randomly dispersed but the logarithmic model generally requires more sampling than the hyperbolic model.     

不同地形部位喀斯特森林物种多样性的比较研究――以贵州茂兰自然保护区为例

选择茂兰国家级喀斯特森林自然保护区为研究对象,对区内不同地形部位的植被进行群落学调查,分析了不同地形部位的植物物种多样性特征,并对喀斯特森林物种多样性维持机制进行探讨。结果表明: ( 1)槽谷森林的物种数S、丰富度指数R 1及物种多样性指数H′最大,分别为76、4. 477和5. 102;其次为漏斗森林,分别为68、4. 059和5. 024;坡地森林的最小,分别为64、3. 110和4. 886。漏斗森林的均匀度指数J 最大,为0. 825,其次为槽谷森林,为0. 816,坡地的相对较小,为0. 814。生态优势度指数λ与均匀度指数相反。( 2)三种地形部位喀斯特森林均以灌木的物种丰富度和多样性指数最大,其次为草本和藤本植物,乔木的最小。( 3)多样性指数随地形部位的变异程度草本植物和灌木物种大于乔木和藤本植物物种。喀斯特生境的高度异质性是喀斯特森林物种多样性维持的基础。     

An analysis of vegetation indices in relation to tree species diversity using by satellite data in the northern forests of Iran

Vegetation indices have been introduced for analyzing and assessing the status of quantitative and qualitative characteristics of vegetation using satellite images. However, choosing the best indices to be used in forest biodiversity and vegetation is one of the important problems faced by the users. The purpose of this research is to evaluate six vegetation indices in the analysis of tree species diversity in the northern forests of Iran. The present research uses LISS III sensor data from IRS-P6 satellite. Geometric rectification of images was performed using ground control points, and Chavez model was used for atmospheric correction of the data. The six spectral vegetation indices included NDVI, IPVI, Ashburn Vegetation Index (AVI), TVI, TTVI, and RVI. Shannon–Wiener species diversity index was used to analyze diversity, and the value of the index was calculated in each sample plot. Then, the spectral values of each sample plot were extracted from different bands. The best subset regression was used to analyze the relationship between species diversity and the related bands. The results obtained from the regression showed that polynomial equations under scrutiny as independent variables can assess tree and shrub species diversity better than other bands and compounds used (R ²?=?0.47). The obtained results also indicated a higher capacity in the case of the AVI index for estimating tree species diversity in the under study area.     

Stable carbon isotope characteristics of different plant species and surface soil in arid regions

The stable carbon isotope composition in surface soil organic matter (δ¹³Csoil) contains integrative information on the carbon isotope composition of the standing terrestrial plants (δ¹³Cleaf). In order to obtain valuable vegetation information from the δ¹³C of terrestrial sediment, it is necessary to understand the relationship between the δ¹³C value in modern surface soil and the standing vegetation. In this paper, we studied the δ¹³C value in modern surface soil organic matter and standing vegetation in arid areas in China, Australia and the United States. The isotopic discrepancy between δ¹³Csoil and δ¹³Cleaf of the standing dominant vegetation was examined in those different arid regions. The results show that the δ¹³Csoil values were consistently enriched compared to the δ¹³Cleaf. The δ¹³Cleaf values were positively correlated with δ¹³Csoil, which suggests that the interference of microorganisms and hydrophytes on the isotopic composition of surface soil organic matter during soil organic matter formation could be ignored in arid regions. The averaged discrepancy between δ¹³Csoil and δ¹³Cleaf is about 1.71%in Tamarix L. in the Tarim Basin in China, 1.50% in Eucalytus near Orange in Australia and 1.22% in Artemisia in Saratoga in the United States, which are different from the results of other studies. The results indicate that the discrepancies in the δ¹³C value between surface soil organic matter and standing vegetation were highly influenced by the differences in geophysical location and the dominant species of the studied ecosystems. We suggest that caution should be taken when organic matter δ¹³C in terrestrial sediment is used to extract paleovegetation information (C₃/C₄ vegetation composition), as the δ¹³C in soil organic matter is not only determined by the ratio of C₃/C₄ species, but also profoundly affected by climate change induced variation in the δ¹³C in dominant species.     

岩溶区不同母岩植物群落物种组成及优势种群生态位差异

以广西平果市纯石灰岩、石灰岩夹白云岩天然次生林为研究对象,在野外群落调查基础上,应用Levins生态位宽度和Pianka生态位重叠指数进行优势种群生态位特征分析。结果表明:纯石灰岩生境下调查到维管植物56种,隶属于35科45属,石灰岩夹白云岩生境下调查到维管植物44种,隶属于33科42属。两种生境下桑科（Moraceae）物种丰富度均占有明显优势,主要为榕属及波罗蜜属。豆科（Leguminosae）、荨麻科（Urticaceae）、楝科（Meliaceae）植物在纯石灰岩生境占优势;大戟科（Euphorbiaceae）植物在石灰岩夹白云岩生境下占优势,群落总体相似性较低。乔木层植物蚬木（Excentrodendron hsienmu）、灌木层植物葡萄叶艾麻（Laportea violacea）与草本层植物肾蕨（Nephrolepis cordifolia）为两种母岩生境植被中的共有物种且生态位宽度指数较高。纯石灰岩森林乔木层与灌木层优势种生态位完全不重叠种对数量较石灰岩夹白云岩森林高14对,纯石灰岩森林乔木、灌木物种相对丰富。在岩溶区进行植被恢复建设中,应依据不同岩性背景优先选择生态位宽度较宽的物种作为先锋树种,同时考虑与其生态位重叠指数低的树种作为伴生种,避免植物不适宜生长或生态位功能冲突。      

沉水植物黑藻对上覆水中各形态磷浓度的影响

室内模拟研究了沉水植物黑藻对上覆水中不同形态磷浓度的影响及其季节性变化,并从沉水植物生长、间隙水和碱性磷酸酶活性(APA)三方面进行了讨论,进一步揭示磷在浅水湖泊水-沉积物界面的交换机理。结果表明,在本研究条件下,上覆水中各形态磷以溶解性总磷(DTP)为主,其他形态磷浓度变异较大,黑藻降低了上覆水中总磷(TP)、溶解性活性磷(SRP)和DTP浓度,也降低了DTP和SRP占总磷的比例,从而使颗粒态总磷(PP)和溶解性有机磷(DOP)占总磷比例升高。黑藻主要通过吸收上覆水中的磷和抑止沉积物、上覆水中APA使上覆水中各形态磷浓度保持较低水平,其中对SRP和DTP浓度的影响更明显。上覆水中各形态磷浓度呈现明显的季节性变化。在7～8月,TP、SRP和DTP浓度呈下降趋势,并在8月达到最低值;9～10月间有所升高,但仍然维持在较低水平,不同采样时间存在波动。     

旅游活动对龙宫景区不同植被层物种多样性的影响

按照旅游活动程度的强弱将景区分为活动区、缓冲区和对照区,并利用6个物种多样性指数,研究了龙宫风景区旅游活动对不同植被层物种多样性的影响.结果表明,随着游客的大量增多及龙宫风景区基础设施建设的加强,风景区物种组成越来越少,多样性与结构越来越简单.主要表现在:(1)乔木层的丰富度上,表现出缓冲区最大,活动区最小,对照区介于两者之间;在物种均匀度上,表现出活动区＞对照区＞缓冲区的趋势;在物种多样性上,活动区最小,缓冲区其次,对照区最大;从生态优势度来看,对照区最大,活动区最小,缓冲区介于其中.(2)灌木层的物种丰富度上,表现出活动区最小,对照区其次,而缓冲区为最大的趋势;在物种均匀度上,对照区最大,活动区次之,缓冲区最小;在物种多样性上,活动区最小,缓冲区其次,对照区最大;从生态优势度来看,对照区最大,活动区最小,缓冲区介于其中.(3)草本层的物种丰富度上,表现出对照区最小,活动区其次,而缓冲区为最大的趋势;在物种均匀度上,对照区最小,活动区次之,缓冲区最大;在物种多样性上,对照区最小,缓冲区最大,活动区介于其中;从生态优势度来看,呈现出缓冲区＞活动区＞对照区的趋势.     

Holocene flooding and species diversity in southwestern Amazonia

A thick blanket of Holocene alluvium lies over southwestern lowland Amazonia, and may possibly occur throughout much of the Amazon Basin. These deposits resulted from massive, seasonal flooding from about 11,000 to about 5000 yr B.P. that was followed by two cycles of erosion and deposition. Interpretations based on these geologic data suggest that southwestern lowland Amazonia is ecologically an “island” in a state of supersaturated disequilibrium as a result of colonization from Pleistocene refugia on its perimeter, and that habitats of highest diversity may be the most recent in origin. Conservation efforts and studies of Amazonian biogeography, soils, and paleoethnography should be reevaluated in light of the geologic data.     

Impacts of temperature and nutrients on coastal lagoon plant communities

We investigated the independent and interactive effects of nutrient loading and summer water temperature on phytoplankton, drift macroalgae, and eelgrass (Zostera marina) in a coastal lagoon mesocosm experiment conducted from May through August 1999. Temperature treatments consisted of controls that approximated the 9-yr mean daily temperatures for Ninigret and Point Judith Lagoons in Rhode Island (United States) and treatments approximately 4°C above and 4°C below the controls. Nutrient treatments consisted of the addition of 6 mmol N m⁻²d⁻¹ and 0.5 mmol P m⁻² d⁻¹ to mesocosms 4°C above and 4°C below the 9-yr daily mean. Nutrient enrichment produced marked phytoplankton blooms in both cool and warm treatments during early summer. These were replaced after midsummer by dramatic growths of macroalgal mats ofEnteromorpha flexuosa and, to a lesser degree,Cladophora sericea. No phytoplankton blooms were observed in the cool unenriched treatments, but blooms did develop in the mean temperature and warm mesocosms during the second half of the summer that were similar in intensity, though of shorter duration, than those observed earlier in the enriched systems. Macroalgal blooms did not occur in the unenriched mesocosms. Sustained warm water temperatures markedly decreased eelgrass density and belowground production and increased the time interval between the initiation of new leaves, particuarly when the biomass of macroalgae was high. The negative effect of elevated water temperature on eelgrass was significantly increased under conditions of elevated inorganic nutrient input. By the end of summer, virtually all of the measures of eelgrass health declined in rank order from cool, to mean, to cool enriched, to warm, to warm enriched treatments. It is likely that the marked declines in eelgrass abundance observed during recent decades in the Northeast have resulted from an interaction of increasing nutrient enrichment combined with increasing summer water temperatures.     

亚热带落叶乔木叶蜡正构烷烃单体碳同位素季节变化特征及影响因素

叶蜡正构烷烃单体碳同位素组成已经成为陆相沉积古生态重建的重要研究方法。现代过程研究是提升叶蜡正构烷烃指标解译的重要环节,而目前关于落叶乔木叶蜡烷烃单体碳同位素组成(δ¹³C_alk)的季节性变化研究还比较有限。本文对两种典型亚热带落叶乔木（小叶栎、枫香）开展了为期2年的叶蜡烷烃δ¹³C_alk研究。两个树种叶蜡烷烃的δ¹³C_alk值在春季偏正,随后迅速偏负,秋季变幅较小,趋于稳定。这种季节性变化特征和初期利用储存的老碳而后期利用新合成的糖类有关。在生长季末期,两种落叶乔木叶蜡烷烃相对于叶片的碳同位素分馏系数处于-6‰～-8‰,相对于文献报道的平均值偏负,这可能是因为生长季后期仍有少量的长链正构烷烃合成。研究结果揭示,基于落叶乔木叶蜡烷烃单体碳同位素进行古环境重建时需要考虑环境信号的季节性。     

Accumulation of heavy metals in soil and uptake by plant species with phytoremediation potential

Contamination of heavy metals represents one of the most pressing threats to water and soil resources, as well as human health. Phytoremediation can be potentially used to remediate metal contaminated sites. In this study, concentrations of copper, zinc, iron, and magnesium accumulated by native plant species were determined in field conditions of Hame Kasi iron and copper mine in the central part of Iran in Hamadan province. The results showed that metal accumulation by plants differed among species and tissue bodies. Species grown in substrata with elevated metals contained significantly higher metals in plants. Metals accumulated by plants were mostly distributed in root tissues, suggesting that an exclusion strategy for metal tolerance exists widely amongst them. The mentioned species could accumulate relatively higher metal concentrations far above the toxic concentration in the plant shoots. With high translocation factor, metal concentration ratio of plant shoots to roots indicates internal detoxification metal tolerance mechanism; thus, they have potential for phytoextraction. The factors affecting metal accumulation by plant species including metal concentrations, pH, electrical conductivity, and nutrient status in substrata were measured. Mostly, concentrations of zinc and copper in both aboveground and underground tissues of the plants were significantly, positively related to their total in substrata, while iron, zinc, and copper were negatively correlated to soil phosphorus.     

Comparison of surrogate models with different methods in groundwater remediation process

Surrogate modelling is an effective tool for reducing computational burden of simulation optimization. In this article, polynomial regression (PR), radial basis function artificial neural network (RBFANN), and kriging methods were compared for building surrogate models of a multiphase flow simulation model in a simplified nitrobenzene contaminated aquifer remediation problem. In the model accuracy analysis process, a 10-fold cross validation method was adopted to evaluate the approximation accuracy of the three surrogate models. The results demonstrated that: RBFANN surrogate model and kriging surrogate model had acceptable approximation accuracy, and further that kriging model’s approximation accuracy was slightly higher than RBFANN model. However, the PR model demonstrated unacceptably poor approximation accuracy. Therefore, the RBFANN and kriging surrogates were selected and used in the optimization process to identify the most cost-effective remediation strategy at a nitrobenzene-contaminated site. The optimal remediation costs obtained with the two surrogate-based optimization models were similar, and had similar computational burden. These two surrogate-based optimization models are efficient tools for optimal groundwater remediation strategy identification.     

磨刀溪梯级水电开发对河岸植物群落的影响

于2008年采用植被常规调查方法,对磨刀溪干流3个引水式电站对河岸植物的影响进行调查研究,按影响情况,各电站设3个采样点.用植物生活型、物种多样性等参数,衡量小水电对河岸植物群落的影响.共采集到维管植物157种,其中乔木21种,灌木19种,草本植物117种.结果表明:各样地之间河流生境物理因子(流速、水深、底质类型、底质异质性)之间存在显著性差异;总的物种丰富度和草本植物的物种丰富度在各样地间存在显著性差异,乔木和灌木物种丰富度差异不显著;物种多样性方面,各样地之间差异性显著;湿生植物物种丰富度分析表明,小水电的修建,造成坝下样地湿生植物成分较低,与坝上样地和电站出水口样地有明显差异.研究认为,引水式电站的修建使河流河岸植被的连续性受到干扰,不利于河流生物多样性的保护.     

Germination and growth of six plant species on contaminated soil with spent oil

Effects of contaminated soil with spent oil on germination, above ground height and biomass of six herbaceous plant species were investigated by conducting a general phytotoxicity test and growth inhibition assessment. Six local plant species were used in order to investigate plant’s ability to germinate and survive in a gradient of contaminated soil with spent oil. The species selected for this experiment include one species of Fabaceae (Medicago truncatular), four species of Gramineae (Bromous mermis, Secal seral, Triticum sativa and A gropyron deserterum) and one species of Linaceae (Linum ussitasimum). Inhibitory effect of contaminated soil on germination, height of young seedling and dry weight were measured. In this study an artificial soil with a light texture included 85% sand, 10% silt and 5% clay was used. The exposure to the contaminated soil carried out using four consecutive concentrations (25, 50, 75, 100 g/kg). Results obtained from the current investigation indicate that all species perform dose-dependent responses to the contaminated soils. Reduction in germination, above ground height and biomass for all species were significantly (P < 0.05) different when compared to their controls, however, Medicago truncatular performed the highest and Linum ussitatisimum the lowest inhibitory effect for germination, above ground height and dry weight of seedling.     

古生物物种分异度计算和绘图的计算机化

本文采用ＢＡＳＩＣ程序,方便、快捷、准确地绘制出了物种分异度图,并与其它应用软件资源共享,绘制出的图件显得整洁、美观,充分显示了计算机技术的优越性     

Evolution of species diversity of Cretaceous radiolarians from high-latitude paleobiochores

Cretaceous radiolarians of the Boreal regions are considered. Their minimal diversity and low abundance are recorded in stratigraphic intervals corresponding to anoxic events. Paleogeographic and ecostratigraphic distribution trends of Cretaceous radiolarians are established for families Heliodiscidae, Prunobrachidae, Pseudoaulophacidae and some others. The most significant turnovers in evolution of radiolarians are confined to the latest Jurassic-earliest Cretaceous, Albian-Cenomanian, Cenomanian-Turonian, terminal Santonian-earliest Campanian transitions and to the terminal Late Cretaceous.