The taxonomical and functional diversity of three groups of aquatic insects in rheocrene karst springs are affected by different environmental factors

Karst springs represent valuable and often the most threatened habitats in the riverine landscape. Unlike other stream habitats, they have several specifics that determine their insularity in the river continuum, e.g., high seasonal thermal and chemical stability. The presented study aimed to find out the taxonomical and functional richness of three groups of aquatic insects (Ephemeroptera, Plecoptera and Trichoptera) in the Western Carpathians karst springs, as well as uncover the mechanism of the EPT community assembly. Low within-site species richness was generally found, however, there was high between-site diversity and thus high total diversity of the studied groups of benthic invertebrates as well. Species richness of the EPT community was higher in larger and colder springs: those with lower concentrations of CO₂ and Fe, as well as higher concentrations of SO₄²⁻. Analysis of functional richness, as well as functional dispersion, did not reveal any clear assembly mechanism in the spring EPT community; however, both analyses indicated a higher proportion of environmental filtering there. Unlike the taxonomic richness, the functional richness of the EPT community was significantly higher in small and medium springs with higher water temperatures, as well as in springs with the presence of deadwood. Between-site dissimilarities in the functional composition of EPT were significantly correlated with environmental differences of springs, which determined variables such as spring size and temperature, as well as the concentration of CO₂ and SiO₂.     

What makes a species synurbic?

The term ‘synurbic’ is sometimes used within the more recent urban ecology literature to refer to a species that colonises or is found within urban ecosystems, but this is too simplistic an interpretation. We consider that the term should be reserved for species populations that have higher densities in urban compared to rural areas, as a quantifiable measure of preferential urban association. This paper clarifies the terms ‘synurbic’ and ‘synurbization’ and considers some of the problems of defining ‘urban’, before detailing some of the positive responses exhibited by urban species that may lead to synurbic populations. It may be particularly important to determine whether responses drive directional selection leading to adaptation and genetic differentiation, or are within the range of expected phenotypic plasticity, and observed responses are discussed within this context. Further investigation of species response to urban environments, including the frequency and significance of adaptation, will be important for understanding the emergence of synurbic populations and their implications for urban biodiversity and management. We hope that the terms defined here will form the basis for comparative studies of urban species.     

皖江滩地杨树抑螺防病林下植物多样性分析

以时空互代的方法,对皖江段滩地不同林龄的杨树人工林林下植物多样性进行了调查。结果表明:①杨树人工林林下以草本植物为主,居于前4位的优势科分别是菊科(9种)、禾本科(6种)、豆科(5种)、蓼科(5种),优势种以萝藦、菱叶鹿藿、无辣蓼、葎草为主。木本植物有桑科桑树、蔷薇科野蔷薇;②滩地造林后,林下植物的丰富度、多样性指数、均匀度指数均高于无林滩地上以芦苇为主的群落;③随着人工林林龄的增加,多样性指数表现出了先降低后上升的趋势,3年生的人工林丰富度(S)、多样性指数(D,H′)最高,20年生的人工林均匀度指数最高。滩地造林后植物多样性有一定程度增加,但成林后植物多样性又逐年减少。     

Ecological and species diversity of arid Mediterranean grazing land vegetation

This study was conducted in the arid Mediterranean Reserve located in northern Jordan, representing a continuous grazed arid rangeland ecosystem. Quantitative analyses on species diversity in addition to phytogeographical analysis were conducted. Some ecological parameters such as, life forms, growth forms, species density and frequency were investigated. A total of 93 vascular plant taxa belonging to 78 genera and 26 families were reported. This constitutes about 4.3% of the total flora of Jordan. Reported taxa include 13 species of grasses, 69 forbs and 10 shrubs and semi-shrubs. The botanical survey pointed to the presence of four rare species in Jordan. Plant species were classified into 28 functional groups. Pairwise correlation analyses among the most abundant species, showed that neutral associations dominated (75%) those communities, followed by positive associations (19%), while only (6%) showed negative association. Positive association may be attributed to direct facultative mutualism, or to physical environmental heterogeneity. Such a positive cooperation in the plant community can significantly maintain species diversity in adverse environments.The relationship between primary productivity and species richness showed a humpbacked pattern. Maximum richness corresponded to a biomass level of 300–400 g m⁻². However, a sinusoidal curve-fitting model explained the relationship between graminoids biomass and species richness. These findings pointed to the adaptation of plant taxa to livestock grazing and to the small-scale spatial and environmental heterogeneity in arid Middle Eastern Mediterranean rangelands. Results suggest that optimal biodiversity conservation for the arid Middle Eastern grazing lands should consider their high level of spatial heterogeneity. Rangeland managers should adopt grazing plans that apply a range of grazing pressure across the area so as to maintain diversity at local and regional scales.     

Changes of Acute Toxicity of Organic Chemicals to Daphnia magna in the Presence of Dissolved Humic Material (DHM)

With a series of substituted anilines, a series of substituted phenols as well as diazinon and tetrabromobisphenol-A alterations of short-term acute toxicity to the waterflea Daphnia magna have been studied in the presence of dissolved humic material (DHM). The results may be categorised as follows: No alteration in acute toxicity occurred with: tetrabromobisphenol-A, o-toluidine, 3,4-dichloroaniline, and pentachlorophenol. Toxicity decreases significantly with: diazinon, 4-chloroaniline, and 4-nitrophenol. Significant toxicity increases were observed with 2,4-dichlorophenol and 2,4,5-trichlorophenol. As demonstrated for diazinon, our study reveals that in the presence of DHM and light the chemical speciation of this chemical is altered and daughter products are produced most likely via photoactive species of DHM. Most probably the toxicity of both the parent and daughter compounds is changed as well. Alterations in acute toxicity of organic chemicals may thus be attributed to the adsorption to DHM as well as to the photoactive species mediated production of daughter products with toxicity different from that of the parent compounds.     

美国弗蒙特州两种濒危鸟类保护成效研究

本文以美国弗蒙特(Vermont)州濒危鸟类游隼(Falco peregrinus)和潜鸟(Gavia immer)为例,反映鸟类与环境的关系,说明人类活动对环境及野生动物的影响,濒危动物的拯救工作应把环境综合治理放在重要位置。     

绿辉石角闪石玉——缅甸非翡翠玉新品种

绿辉石角闪石玉是近来缅甸发现的一个非翡翠玉类的新品种。矿物成分主要为高压带的角闪石,不均匀分布少量绿辉石及蓝闪石。     

Analysis and speciation of selenium ions in mine environments

 Aqueous extracts of five mine soil samples and a set of selenite (SeO₃ ^2–)–selenate (SeO₄ ^2–) solutions (0.5, 1, 5, 10 and 25 mg/l) were speciated using atomic absorption spectroscopy with hydride generation (AAS-HG) and ion chromatography (IC) to compare these methods for Se speciation. In another experiment, a SeO₃ ^2––SeO₄ ^2––SO₄ ^2– solution (25 mg/l) was reacted with CaO, MgO, MnO₂, CuO, La₂O₃, and WO₃ to evaluate the relative distribution of the Se species and SO₄ ^2– in the SORB (sorbed ions that were desorbed by NaOH), SOLN (equilibrium concentrations), CMPX (irreversibly sorbed and neutral ion pair complexes) fractions. The AAS-HG method was capable of analyzing Se as low as 0.002 mg/l, which was below the detection limit of IC. High concentration of SO₄ ^2– affected the chromatographic Se speciation either by shifting or overlapping Se peaks, in which AAS-HG was more useful. However, IC was capable of speciating aqueous SeO₃ ^2––SeO₄ ^2– directly without any sample pretreatment, whereas AAS-HG measured SeO₃ ^2–+SeO₄ ^2–, and SeO₃ ^2– in separate runs and SeO₄ ^2– was calculated from the difference, i.e., spectrophotometric speciation was an indirect method. For both Se species, AAS-HG and IC data were comparable within detection standard deviations. Ratios of different Se species at measured soil pH and pe indicated that SeO₃ ^2– or SeO₄ ^2– would be the dominant Se species; the p(SeO₄ ^2–/SeO₃ ^2–) values further suggested SeO₄ ^2– would be the major solution species. Except for CaO and MgO treatments, the %SeO₃ ^2– in the SORB fraction was ≥%SeO₄ ^2–. In the SOLN fraction %SeO₄ ^2– was ≥%SeO₃ ^2– for all oxides but CaO, whereas in the CMPX fraction this order was observed for only CaO and MnO₂. The %SeO₃ ^2– was highest in the SOLN fraction for all oxides but MgO and La₂O₃ for these two oxides SeO₃ ^2– dominated in CMPX and SORB fractions, respectively. The SOLN fraction also contained the highest %SeO₄ ^2– for all oxides but MgO which retained SeO₄ ^2– primarily in the SORB fraction. The %SeO₃ ^2– and %SeO₄ ^2– in the CMPX fraction were highest for MgO, thus, suggesting a possible formation of MgSeO₃ ⁰ and MgSeO₄ ⁰. A similar trend of SORB %SO₄ ^2– and SORB %SeO₄ ^2– was attributed to the analogous adsorption mechanisms (outer-sphere complexation). For all oxides but MgO, %SO₄ ^2– was <%SeO₄ ^2– in the SOLN fraction and ≥%SeO₄ ^2– in the CMPX fraction. Comparative ionic distributions provide an overall picture of the relative abundance of different Se species in various fractions associated with different oxides present in micro- and macrolevels in soils and geological materials. Received: 27 December 1995 · Accepted: 29 April 1997     

Identifying and Quantifying Disjunctions at Multiple Taxonomic Levels in Western Hemisphere Mammals

I surveyed more than 1,700 Western Hemisphere mammal species ranges to identify, quantify, and examine patterns of disjunction at multiple taxonomic levels. Species that had disjunct populations (isolated by at least 500 km from other parts of the species range) were further analyzed using novel measures of disjunction by determining the distance to the disjunction and the relative area of disjunctions compared to the primary range area. Disjunction at this scale is rare (6.4 percent) in all terrestrial mammals but more common in bats (14.6 percent) than nonvolant mammals. Disjunctions are concentrated in six families, specifically Molossidae (31.5 percent disjunct), Didelphidae (24.7 percent disjunct), Felidae (28.6 percent disjunct), Vespertilionidae (15.3 percent disjunct), Emballonuridae (10.5 percent disjunct), and Phyllostomidae (10.4 percent disjunct). Geographically, 85 percent of disjunct mammal species have ranges that occur entirely or partially in South America. Geographic information systems analysis of species range maps is capable of identifying disjunct species and evaluating the severity of disjunctions. When compiled at the family level, these data suggest that species in certain families are more susceptible to disjunction. In some cases (e.g., species ranges separated by the Amazon rainforest), species-level data offer insight into the causes of disjunction. Study of species identified as disjunct in this study can inform conservation efforts by providing an opportunity to determine the characteristics that enable them to survive as isolated populations.     

Above ground biomass and tree species richness estimation with airborne lidar in tropical Ghana forests

Estimates of forest aboveground biomass are fundamental for carbon monitoring and accounting; delivering information at very high spatial resolution is especially valuable for local management, conservation and selective logging purposes. In tropical areas, hosting large biomass and biodiversity resources which are often threatened by unsustainable anthropogenic pressures, frequent forest resources monitoring is needed. Lidar is a powerful tool to estimate aboveground biomass at fine resolution; however its application in tropical forests has been limited, with high variability in the accuracy of results. Lidar pulses scan the forest vertical profile, and can provide structure information which is also linked to biodiversity. In the last decade the remote sensing of biodiversity has received great attention, but few studies focused on the use of lidar for assessing tree species richness in tropical forests.This research aims at estimating aboveground biomass and tree species richness using discrete return airborne lidar in Ghana forests. We tested an advanced statistical technique, Multivariate Adaptive Regression Splines (MARS), which does not require assumptions on data distribution or on the relationships between variables, being suitable for studying ecological variables.We compared the MARS regression results with those obtained by multilinear regression and found that both algorithms were effective, but MARS provided higher accuracy either for biomass (R² = 0.72) and species richness (R² = 0.64). We also noted strong correlation between biodiversity and biomass field values. Even if the forest areas under analysis are limited in extent and represent peculiar ecosystems, the preliminary indications produced by our study suggest that instrument such as lidar, specifically useful for pinpointing forest structure, can also be exploited as a support for tree species richness assessment.