Showing papers on "Diversity index published in 2001"

Seasonal variation in the diversity and species richness of phytoplankton in a tropical eutrophic reservoir

Abstract: A one year study was carried out in a tropical eutrophic reservoir (Pampulha Reservoir, Brazil). Species richness and diversity (Shannon–Wiener, H') were measured at two week intervals at one collection site. Indices were calculated on an individual, cell and biomass basis. Because of the relative importance of colonial species in this reservoir, calculations based on biomass were the best descriptors for the studied environment. Climatic changes, especially rainfall, were important to explain the seasonal variation observed, acting as a possible disturbing factor and improving diversity. The calculation of diversity indices was important to demonstrate the instability of this system, which for most of the year does not allow the dominance of a single species, and showed high H' values.

On the measurement of species diversity incorporating species differences

Abstract: When pairwise differences (relatedness) between species are numerically given, the average of the species differences weighted by relative frequencies can be used as a species diversity index. This paper first theoretically develops the indices of this type, then applies them to forestry data. As examples of diversity indices, this paper explores the taxonomic diversity and the newly introduced amino acid diversity, which is a modification of the nucleotide diversity in genetics. The first, mathematical part shows that both indices can be decomposed into three inner factors; evenness of relative frequencies (=the Simpson index), the simple average over species differences regardless of relative frequencies, and the taxonomic or genetic balance in relative frequencies. The taxonomic diversity has another decomposition: the sum over the Simpson indices at all the taxonomic levels. The second part examines the effects of different forest management techniques on diversity. It is shown that a thinning operation for promoting survival of specific desirable species also contributed to increasing the taxonomic diversity. If we calculated only conventional indices that do not incorporate species relatedness, we would simply conclude that the thinning did not significantly affect the diversity. The theoretical developments of the first part complement the result, leading us to a better interpretation about contrasting vegetation structures. The mathematical results also reveal that the amino acid diversity involves redundant species, which is undesirable when measuring diversity; hence, this index is used to demonstrates crucial points when we introduce species relatedness. The results suggest further possibilities of applying diversity indices incorporating species differences to a variety of ecological studies.

The genetic diversity of annual wild soybeans grown in China

Abstract: Annual wild soybeans (Glycine soja), the ancestors of cultivated soybeans (G. max), are important sources of major genes for resistance to pests, diseases and environmental stresses. The study of their genetic diversity is invaluable for efficient utilization, conservation and management of germplasm collections. In this paper, the number of accessions, the variation of traits, the genetic diversity indexes (Shannon index) and the coefficient of variation were employed to study the geographical distribution of accessions, genetic diversity of characters and genetic diversity centers of annual wild soybean by statistical analysis of the database from the National Germplasm Evaluation Program of China. Most annual wild soybeans are distributed in Northeast China, and the number of accessions decreases from the Northeast to other directions in China. The genetic diversity indexes (Shannon index) were 0.49, 0.74, 0.02, 0.55, 1.45, 2.41, 1.27 and 1.89 for flower color, sootiness of seed coat, cotyledon color, pubescence color, hilum color, leaf shape, stem type and seed color, respectively. Coefficients of variation were 7.1%, 28.7%, 76.43% and 18.2% for protein content, oil content, 100-seed weight and days to maturity, respectively. Three genetic diversity centers, the Northeast, the Yellow River Valley and the Southeast Coasts of China, are proposed based on the geographical distribution of the number of accessions, genetic diversity and the multivariate variation coefficient. Based on these results and Vavilov’s theory of crop origination, two opposing possible models for the formation of the three centers are proposed, either these centers are independent of each other and the annual wild soybeans in these centers originated separately, or the Northeast center was the primary center for annual wild soybeans in China, while the Yellow River Valley center was derived from this primary center and served as the origin for the Southeast Coast center.

Relationship between plant species diversity and grassland condition.

Abstract: Although the maintenance of biodiversity has become one of the goals in ecosystem management, the relationships of diversity to ecosystem characteristics such as level of herbivory, productivity, and vegetation structure are still poorly understood. We examined these relationships in 8 native grassland sites differing in grazing histories and range condition in the Mixed Grassland (6), Moist Mixed Grassland (1) and Aspen Parkland (1) ecoregions of southern Saskatchewan. Range condition, assessed using standard methods, ranged from fair to excellent. The Shannon's diversity index followed a curvi-linear relationship with range condition, increasing from fair to good, but decreasing from good to excellent condition, within a range between 0.66 and 2.58. Species evenness was affected by range condition in a similar manner ranging from 0.44 to 0.86. Species richness varied among sites and plots between 4 and 28 plants 0.25 m(-2), but changed little with range condition. Most structural parameters, such as the cover, height, or thickness of standing plants (live or dead) and litter, increased with range condition especially from good to excellent. The Shannon's diversity index was positively correlated with forb biomass, but not with biomass of any other group or their combination. Grazing regimes that maintain good range condition also maintain species and structural diversity of grasslands. DOI:10.2458/azu_jrm_v54i2_bai

A comparison between diversity, similarity and biotic indices applied to the macroinvertebrate community of a small stream: the Ravella river (Como Province, Northern Italy)

Abstract: This study aimed at comparing the results obtained by processing a series of data according to several diversity indices (Simpson, Berger-Parker, Margalef, Menhinick, McIntosh, Shannon) and one similarity index (Jaccard) with those obtained from two biotic indices (Trent River Biotic Index, Extended Biotic Index). In addition, Cody's index was adopted to measure the species turnover along the stream gradient. The source of the data was a study of the seasonal variations of macroinvertebrates from the Ravella stream (Como Province, Northern Italy). The conclusions are the following. There is clearly a certain connection between the organic debris in the habitat, the abundance of individuals and the decrease in the diversity value of the macroinvertebrate association. The species turnover along the stream gradient is rapid which is due, in addition to birth and death rates, to the fact that most of the insects emerge as terrestrial adults. The species abundance distribution is a very simple and powerful tool for describing and comparing the species diversity from different sampling stations. Any type of monitoring (e.g., biotic indices, diversity indices) is useful in comparing non-polluted and heavily polluted environments. Conversely, small differences between species associations are better highlighted if diversity indices with high discriminant ability (e.g., Simpson's index) or species abundance distribution are used rather than biotic indices.

The zooplankton community in bays of Toulon area (northwest Mediterranean Sea, France)

Abstract: The abundance and the diversity of the zooplankton community were studied during an annual cycle in three shallow bays differently affected by anthropogenic inputs of Toulon area in the northwest Mediterranean Sea (France). Environmental variables of water quality were also considered. Our results discriminated Little Bay from the La Garonne and Niel Bay. Little Bay, heavely perturbed by anthropogenic inputs, had high chlorophyll a levels, abundant zooplankton, a low diversity index, a high dominance Index and a single dominant species (Oithona nana). La Garonne Bay and Niel Bay, much less polluted, had low chlorophyll a levels, low zooplankton abundance, low dominance Index and high diversity index and eveness. In addition, O. nana occurred rarely in the latter bays. Zooplankton successions were also different between Little Bay and the two other bays.

Landscape Heterogeneity and Diurnal Raptor Diversity in Honduras: The Role of Indigenous Shifting Cultivation1

Abstract: I studied the relationship between diurnal raptor diversity, density, and richness, and landscape heterogeneity in continuous primary forests and forests farmed by native Amerindians in the Rio Platano Biosphere Reserve of northeastern Honduras from January to June 1996 and 1997. I estimated landscape heterogeneity—the variability in naturally occurring and/or anthropogenic habitat mosaics—by mapping the extent and distribution of five human-modified and natural habitats in 24 1 km2 survey plots. I used the Shannon index to calculate landscape heterogeneity values for the respective plots based on the proportion of total area of each habitat within each plot. Diurnal raptor surveys from canopy-emergent viewpoints in these plots resulted in 137 observations of 18 species of raptors. Four species (Coragyps atratus, Ictinia plumbea, Leucopternis albicollis, and Buteo magnirostris) differed significantly in abundance among heterogeneity classes. Raptor diversity, density, and richness all increased d...

Implications of species loss in freshwater fish assemblages

Abstract: Magurran, A. E. and Phillip, D. A. T. 2001. Implications of species loss in freshwaterfish assemblages. – Ecography 24: 645–650.Freshwater systems are vulnerable to pollution and species loss often ensues. Arethere additional implications for assemblage structure? Here we use Berger-Parker d,Simpson’s 1/D and Simpson’s E to measure the ecological diversity of pristine andperturbed freshwater fish assemblages in Trinidad, West Indies, and Oklahoma,USA. Although the impacted sites typically had fewer species than expected, theycould not be distinguished from unperturbed ones of equivalent richness. Changes inthe evenness of these assemblages are thus driven by changes in richness. Onepractical outcome is that diversity indices may not provide independent verificationof the detrimental consequences of pollution. The similarity in structure of naturallyand anthropogenically impoverished assemblages provides no grounds for compla-cency, however, since it ignores the evolutionary history of the species concerned. Onthe basis of our results we suggest that species provenance may be important in testsof ecological function. Moreover, these investigations should replicate natural pat-terns of evenness as well as richness.

Scarabaeidae (Coleoptera) do Parque Estadual Mata dos Godoy e de área de pastagem, no norte do Paraná, Brasil

Abstract: The environmental transformations constitute the principal cause of changes in biodiversity decrease. This make the comparative studies between natural and altered environments very important. This work compare the fauna of Scarabaeidae at the following areas: isolated forest fragment and pasture at the secondary stage of succession. Scarabs beetles were collected using four pitfall traps baited with cattle meat in each habitat, fortnightly from November 1998 to April 1999. It was collected a total of 3,113 individuals from 32 species in forest and 956 individuals from 27 species in pasture. The Sorensen index was used to calculate similarity, and Shannon index to calculate diversity. The qualitative similarity found was 0.64 and the quantitative similarity was 0.10. A relevant difference was found in the diversity of two localities, the value found in pasture was 1.75 and in forest was 2.44; these values were significantly different by T test (p<0.001). Our results suggest that the changes in forest area for pasture area caused losses concerning biodiversity of Scarabaeidae and the respective functions of these organisms in the ecosystem.

Land-snail faunas in indigenous rainforest and commercial forestry plantations in Kakamega Forest, western Kenya

Abstract: We examine the diversity and structure of land-snail faunas in indigenous rainforest communities and three types of forestry plantation in Kakamega Forest, western Kenya. Using plot-based, standardized sampling consisting of fixed-time direct searching and fixed-volume litter sieving we estimated molluscan diversity and abundance in monoculture plantation plots of the exotic, non-African tree species Bischofia javanica and Pinus spp., and the central African tree Maesopsis eminii which is an indigenous component of the Kakamega rainforest. Overall, 41, 39, 41 and 34 mollusc species were recorded in indigenous forest, Maesopsis, Bischofia and Pinus plantations respectively. The mean number of species and mean number of specimens per plot were 15–49% and 6–54% lower respectively in the plantations relative to indigenous forest. Abundance and species number were suppressed the most in the Pinus stands, and the least in the plantations of indigenous Maesopsis. Species per plot, Shannon index and abundance were lowest in the Pinus plantation and highest in the indigenous forest. Snails were more abundant in Maesopsis than in Bischofia, but mean species per plot and total species number did not differ significantly between these plantation types. Shannon evenness indices showed that the indigenous forest faunas were more uniform in terms of species abundance, whereas the three plantation types were dominated by a small number of species. Several species were confined to the indigenous rain forest. Although most species were present in both indigenous forest and plantations, many species were significantly more abundant in the rainforest communities. The potential use of groups of these species as indicators of forest conditions is discussed. Overall, the Maesopsis and Bischofia plantations support a substantial proportion of the indigenous rainforest's mollusc fauna. This maybe partly because of the relatively close proximity of indigenous stands to plantations, which can facilitate recolonisation. However, the finding illustrates that plantations hold the potential, at least in some circumstances, to provide alternative habitats for forest molluscs where indigenous rainforest has been cleared.

Influence of Site on Diversity and Abundance of Ground- and Litter-Dwelling Coleoptera in Appalachian Oak–Hickory Forests

Abstract: Weevaluatedthefamily-levelrichness,diversity,evenness,andabundanceofground- and litter-dwelling beetles in two forested areas of southeastern Kentucky for 2 yr, and related beetle diversity to habitat characteristics in these deciduous forests. Using pitfall traps and leaf litter samples, we collected over 13,420 beetle specimens in 42 families during this 2-yr study. Carabidae, Scolytidae, and Staphylinidae were the most abundant families in pitfall traps, and Nitidulidae, Staphylinidae, and Pselaphidae were most common in litter samples. Pitfall traps captured the widest array, with 41 beetle families, whereas litter samples produced 25 families. Plots from Robinson Forest had a higher family richness but lower evenness than Kentucky Ridge Forest plots in both 1997 and 1998. The greater evenness of the families at Kentucky Ridge contributed to a higher Shannon index at Kentucky Ridge than at Robinson Forest, though these differences were significant only in 1998. Kentucky Ridge plots tended to be less rocky, with greater amounts of coarse woody debris, less dense herbaceous cover, a smaller mid-canopy component, and less deciduous cover than Robinson Forest. Family richness, diversity, evenness and abundance varied with site, plot, and sample interval, but the site variables we measured were inconsistent in their ability to predict our response variables, as was the multivariate cluster analysis. The effects of site characteristics and habitat complexity on beetle family diversity are discussed.

Structure and species diversity of subtropical evergreen broad-leaved forest in northern Okinawa Island, Japan

Abstract: The structure and tree species diversity of a subtropical evergreen broad-leaved forest in northern Okinawa Island, Japan, were studied. Enumeration of the six sampling plots revealed an average density of 5,580 individuals with DBH≧3.0 cm/ha, having an average basal area of 55 m2. The large-size trees of DBH≧20 cm contributed 10% of the total individuals, and 49% of the total basal area. The forest showed a high diversity of tree species, which is comparable to some tropical rain forests. A total of 54 over-story species of 24 families and a total of 63 understory species of 26 families were identified in the six sampling plots. Fagaceae and Theaceae were the most important families;Castanopsis sieboldii, Schima wallichii andDistylium racemosum were the most important species. The diversity index and equitability index of species were 4.15 and 0.72 for the overstory plots, and 4.72 and 0.79 for the understory subplots, respectively. The diversity index for the overstory was significantly correlated to the total basal area of trees over 20 cm DBH (p 0.16). The size distribution pattern and age structure indicated differences in regeneration strategies for canopy dominants. In population dynamics of the succession process,C. sieboldii andD. racemosum were self-maintaining types, andS. wallichii was a gap- or opening-dependent type.

Species diversity and assemblages of macrobenthic Mollusca from the South Shetland Islands and Bransfield Strait (Antarctica)

Abstract: During the research program BENTART 95, carried out from 16 January to 4 February 1995 on board RV Hesperides, a semi-quantitative Agassiz trawl and quantitative Van-Veen grabs were used at 31 subtidal stations between 40 and 850 m depth around Livingston Island, at Deception Island and in the Bransfield Strait. These data were used to search for and analyse the malacological assemblages. Among the molluscs sampled were 1,786 individuals belonging to 70 species of Solenogastres, Gastropoda Prosobranchia and Opisthobranchia, Scaphopoda and Bivalvia. The values of Shannon-Wiener diversity index ranged between 0.00 (one specimen) and 3.95, while Pielou's evenness index varied between 0.0 and 1.00. The bivalve Thyasira cf. dearborni was the most abundant species (227 specimens). Species richness varied from 1 to 19 species. Diversity showed great variations at different stations. The clustering analysis applying the Bray-Curtis coefficient allowed species classification according to constancy and fidelity, and distinguished four groups of stations: one that gathers clearly the stations of the inner bay of Deception Island, excepting station 1, and the other three fitting the remaining stations, located north and south of Livingston Island and in the Bransfield Strait, and correlated with environmental factors (granulometric composition, organic matter and carbonates).

Species diversity changes in subalpine coniferous forests of different restoration stages and their effects on soil properties

Abstract: The species diversity changes of subalpine coniferous forests at different restoration stages in western Sichuan province were studied and the responses of 17 soil factors to the species diversity changes were examined by multiple regression analyses. The results showed that species diversity tended to increase gradually with the growth of plantation ages and the species composition in layers of arbor,shrub and herbs changed accordingly. However,restoration of species diversity in subalpine coniferous plantations was quite slow. Responses of physical and chemical properties of soil to species diversity changes varied in different stands. Apparent density and water content which are closely related to the water conservation function of the soil were improved along with increasing species diversity. The accumulated litters,organic matters,hydrolyzed acid and the contents of Ca,Mg, and P in soil,the indicators that represent soil nutrition,also increased with the increase of species diversity in the layers of arbor and shrub, but the content of K 2O decreased with the increase of herbage species diversity. We developed the correlative equations of the above mentioned 9 soil factors with the species diversity indices. The other 8 soil factors showed no direct linear correlation with the diversity indices. Protecting and increasing species diversity in subalpine coniferous plantations can improve part of the soil nutrients and promote the restoration of ecological functions.

Vegetation exclusion under Casuarina equisetifolia L.: Does allelopathy play a role?

Abstract: A study conducted to determine the ecological status of vegetation under a Casuarina equisetifolia L. plantation revealed that the number of species types, density and biomass of the understorey were drastically reduced compared to an adjoining grassland area. In general, vegetation under Casuarina was characterised by the presence of a few dominants with a trend towards homogeneity. On the other hand, the vegetation in the grassland was heterogeneous, with conspicuous spatial pattern and, thus, more stable. Indices of richness (indicating numerical strength), evenness (representing spatial distribution), and diversity (combining both richness and evenness) also indicated a marked difference in the vegetation between the two sites. The Shannon index, indices of richness and evenness, and Hill. s diversity measures were greater in grassland areas than in Casuarina plantation, thereby signifying a richer, more diverse and even vegetation in the grassland. In contrast, the Simpson index of dominance which shows an inverse relation with diversity, was greater under the Casuarina plantation. The reasons for the restrained vegetation under Casuarina were explored in terms of allelopathic interference of various tree parts (fresh as well as fallen) as one of the major factor. The leaf leachates collected under the canopy of Casuarina trees in the plantation were found to have deleterious effect on the growth of Medicago sativa and Ageratum conyzoides and were rich in phenolics. The extracts prepared from different tree parts such as needles, female cones and litter adversely affected the growth and dry weight accumulation in M. sativa and A. conyzoides. An appreciable amount of water-soluble phenolics, known phytotoxins, was estimated in the fog leachates and different plant parts under use. It is concluded that phenolics released from the green needles and litter of the tree adversely affect the understorey vegetation.

The Cystoseira spp. Communities from the Aegean Sea (NE Mediterranean)

Abstract: A synthetic study of qualitative and quantitative data from some algal communities dominated by different species of the genus Cystoseira has been carried out in three coastal areas of the Aegean Sea. Seasonal samples were taken from 10 stations and a list of 30 species presenting coverage values > 1% was dressed. Ecological indices, such as Shannon Diversity Index, Pielou Eveness and Bray-Curtis Similarity Index were calculate using the PRIMER software. The results from the Aegean Sea were compared with other Mediterranean areas, and the use of Cystoseira communities as ecological quality indicators was discussed.

Coleopterofauna em floresta e pastagem no norte do Paraná, Brasil, coletada com armadilha de solo

Abstract: The environmental transformations constitute the principal cause of changes in biodiversity. This make the comparative studies between natural and altered environments very important. This research compare the beetle fauna at the following areas: isolated forest fragment and pasture at the secondary stage of succession. Beetles were collected using four pitfall traps baited with cattle meat in each area, fortnightly from November 1998 to April 1999. A total of 17,721 individuals from 30 families of Coleoptera in forest and 6,597 individuals belanging to 32 families in pasture was collected. The Sorensen index was used to calculate similarity, and Shannon index to calculate diversity. The qualitative similarity found was 0.70 and the quantitative similarity was 0.48. The mean Shannon diversity index found was 1.90 for forest and 2.01 for pasture; these values were not significantly different by T test. It was concluded that the beetle decomposer fauna collected was representative in both environments, which also contributes in the decomposition process of organic matter, in soil fertilization and also in control ling egg and larvae populations of parasitic flies.

Influence of Different Stocking Rates on Plant Diversity of Artemisia frigida Community in Inner Mongolia Steppe

Abstract: The experiment was conducted in Inner Mongolia steppe located in 43°26′-44°08′ N, 116°04′-117°05′ E in 1989-1997. The grazing experiment design was 5 stocking rates (0.00, 1.33, 2.67, 4.00, 5.33 and 6.67 sheep·hm -2 , but 0.00, 1.33, 2.00, 2.67, 3.33 and 4.00 sheep·hm -2 in 1990) with three 1 hm 2 rotational paddocks per treatment. The sheep were Inner Mongolia fine sheep and the experiment was performed during warm seasons every year from May 20 to October 5. The objectives were to research the integrated influence of different stocking rates on plant diversity and to provide knowledge of its mechanism by the method of continuous monitoring of 8 years for the same grazing experiment rather than through spatial gradient.The results showed that using the method of 100 m sample line was suitable for estimating the abundance of plant species. Simpson index and evenness were better parameters to measure the influence of different stocking rates on plant diversity for Artemisia frigida community. The plant species abundance almost remained unchanged, but the plant diversity and evenness decreased as the stocking rate increased, and the community dominance increased with stocking rate during the 8 years' grazing under different stocking rates. The interaction of the preferred ingestion of grazing sheep with heavy stocking rate may be one of the key reasons resulting in the decrease of plant diversity and evenness. Grass proportion decreased with the increase of stocking rates and A. frigida community degraded further into Potentilla acaulis community under heavy grazing or over_grazing. The succession and plant diversity of A. frigia community under different stocking rates mainly depend on the dynamics of A. frigida, Cleistogenes squarrosa, Potentilla acaulis, Agropyron cristatum and Carex duriuscula populations; Cleistogenes squarrosa population is one of the 3 populations of maximum abundance under all stocking rates from 1989 to 1997.

Body size and abundance relationship: an index of diversity for herbivores

Abstract: It is evident to any biologist that small-bodied species within a given higher taxon (order, class, phylum, etc.) tend to be represented by more individuals. Hence small-bodied species are generally more abundant than large-bodied species. We analyzed large herbivore species data collected in Kenyan rangelands. An index of biological diversity derived from the negative relation between animal species body size and its local abundance is proposed. We compared the new index with species abundances at landscape scale (10 × 10 km) in individual districts, as well as in the combined regional data. The results show a consistently strong positive relation between the new diversity index and species abundances. The proposed diversity index has the advantage of incorporating information on species abundances without the need for time-consuming surveys.

Changes in backwater plant communities from 1975 to 1995 in Navigation Pool 8, Upper Mississippi River

Abstract: Water elevation in the Upper Mississippi River (UMR) is highly regulated by an extensive system of locks and dams. Completion of this system in the 1930s created productive, biologically diverse backwater habitats. The status of plant communities in these backwater areas may now be threatened by several factors, including sediment accumulation, recreational use, and navigation traffic. Aerial photography, taken in 1975 and from 1991 to 1995, was used to describe vegetation changes occurring in four UMR backwater areas of Navigation Pool 8. The objectives were to determine (1) if changes occurring in these areas are consistent with hydrarch succession, (2) if the diversity of their plant communities has declined since 1975, and (3) how a large flood event that occurred in 1993 affected the composition and diversity of plant communities in these areas. Three general cover classes were recognized, representing an aquatic to terrestrial gradient. Coverages of specific vegetation types were estimated and evaluated using two indices of community diversity (vegetation richness and the Shannon diversity index). Though some vegetation changes were consistent with expected successional patterns (e.g. increased terrestrialization), other changes were not (e.g. loss of marsh vegetation). Diversity indices and coverages of most aquatic macrophytes declined from 1975 to 1991/1992 but then increased following the 1993 flood. The results suggest that disturbance–diversity concepts, including the flood pulse model, are applicable to the vegetation dynamics of these systems. Published in 2001 by John Wiley & Sons, Ltd.

Ground beetle (Coleoptera, Carabidae) diversity in Finnish arable land

Abstract: Carabid data compiled from six independent studies, consisting of 97 799 individuals trapped by pitfalls from Finnish agricultural fields and identified to 111 species were analyzed. Shannon-Wiener H’ diversity index was typically around 2.5 and expected species number rarefied to 600 trapped individuals was typically around 30 species. The five most abundant species accounted for 42% of the total catch, and the thirty most abundant species made up 98% of the total catch. Percentage similarities among the assemblages by PS-index were from 16% to 48%. In comparison to published data about carabid diversity in boreal forests, which form the dominating habitat matrix in which Finnish farmland is embedded as relatively small patches, arable fields harbor more species rich assemblages, with more even rank-abundance distributions but variable species composition. Importance of landscape (regional) level, instead of spatial level of crop fields, in understanding carabid diversity in farmland is discussed. Inclusion of carabids into monitoring schemes of agro-biodiversity at landscape level is suggested.

The species diversity and distribution trends of small mammals in Hengduan Mountains, Yunnan

Abstract: The vertical distribution of small mammals was investigated in seven important mountain ranges of the Hengduan Mountains in Yunnan Province, such as Mt. Gaoligong and Mt. Yunling. The geographical distribution trends, rules and correlaed variables were analyzed, based on the mean diversity indices of small mammals in the vertical zones of these ranges. The results cemonstrated that the species diversity index decreased gradually from the south to the north and from the west to the east. The most important variables were latitude and rainfall. In addition, the peak of small mammals^ density was analyzed and discussed in those areas.

Frequency distribution of Foraminifera in the Chilka Lake

Abstract: A total of sixtynine foraminiferal species have been identified from the sediment samples collected from the Chilka Lake during November 1997 and March, May 1998. These species have been quantitatively studied in regard to their relative abundance and distribution. Frequency distribution study of Foraminifera shows that Miliammina fusca, Ammobaculites exiguus, Trochammina hadai, Jadammina macrescens, Gaudryina exilis, Ammonia beccarii (Linne), A. tepida and Asterorotalia dentata are the dominant species of the fauna. Mean values of number of species (S), Shannon-Wiener index, H (S) and evenness index (H) are highest in summer (May) for the outer channel suggesting very high species diversity of the area as compared with other parts of the lake due to strong marine influence. In contrast, Pielou's index of species dominance (D) decreases towards the sea. Variations in the mean diversity indices for the areas covered in the lake are related to the water characteristics prevailing there during different seasons. The sites dominated by M. fusca and A. exiguus are mostly inside the lagoon, while those dominated by A. beccarii (Linne) besides T. hadai, G. exilis, Hanzawaia asterizans, H. nitidula, A. tepida, A. dentata, Elphidium crispum and E.galvestonense are in the outer channel of the lake. Application of two similarity indices - Bray-Curtis coefficient and Community coefficient - for the data shows very high faunal affinity existing between stations in the northern sector. Furthermore, the degree of faunal variation has been discussed with the data in terms of percent number of species occurring in all the samples of sites (Sc) and of per cent population composed of species occurring in all the samples of sites (Pc) at each of the three areas of the lake.

Effect of chemical fertilizer on nematode community composition and diversity in the Black Soil Region

Abstract: The effects of chemical fertilizer on nematode community composition and diversity were investigated in a field throughout the corn growing season in the Black Soil Region, Northeast China. 14 families and 16 genera were observed. Cephalobidae, Rhabditidae, Aphelenchus , and Tylenchus were found to be the dominant families/genera. Significant differences were found between sampling dates ( p 0.01) and between treatments ( p 0.01) in the total number of nematodes during the study period. Ecological indices of diversity, evenness, richness and dominance and the dynamics of the nematode community were compared between the treatment and the control plot. Shannon index and richness were found to be more sensitive indicators than other ecological indices for assessing the response of nematode communities to the application of chemical fertilizer.