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Different Taxonomic Levels (different + taxonomic_level)
Selected AbstractsMeasuring the amount of statistical information in the EPT indexENVIRONMETRICS, Issue 1 2005Patty L. Kitchin Abstract Biological monitoring is the process of measuring the effect of environmental stress on the environment. Aquatic macroinvertebrates are widely used in the monitoring of freshwater lotic systems. The macroinvertebrate fauna of a reference stream is commonly compared to the fauna of an impacted stream that is affected by an environmental stressor. The smaller the similarity between these two streams, the greater the effect of pollution or stress on the impacted stream. Many richness measures, or statistics, exist for measuring similarity. These statistics can be computed using different levels of taxonomic resolution (species, genus and family). Many aquatic biologists believe that species-level identifications, which require exorbitant time and expertise, are needed for correct data interpretations. The actual amount of information provided by these statistics at different taxonomic levels has never been measured. This article evaluates the amount of statistical information provided by the EPT index as compared to a sufficient statistic at the various levels of taxonomic resolution. Copyright © 2004 John Wiley & Sons, Ltd. [source] Plant species richness of nature reserves: the interplay of area, climate and habitat in a central European landscapeGLOBAL ECOLOGY, Issue 4 2002Petr Py Abstract Aim To detect regional patterns of plant species richness in temperate nature reserves and determine the unbiased effects of environmental variables by mutual correlation with operating factors. Location The Czech Republic. Methods Plant species richness in 302 nature reserves was studied by using 14 explanatory variables reflecting the reserve area, altitude, climate, habitat diversity and prevailing vegetation type. Backward elimination of explanatory variables was used to analyse the data, taking into account their interactive nature, until the model contained only significant terms. Results A minimal adequate model with reserve area, mean altitude, prevailing vegetation type and habitat diversity (expressed as the number of major habitat types in the reserve) accounted for 53.9% of the variance in species number. After removing the area effect, habitat diversity explained 15.6% of variance, while prevailing vegetation type explained 29.6%. After removing the effect of both area and vegetation type, the resulting model explained 10.3% of the variance, indicating that species richness further increased with habitat diversity, and most obviously towards warm districts. After removing the effects of area, habitat diversity and climatic district, the model still explained 9.4% of the variance, and showed that species richness (i) significantly decreased with increasing mean altitude and annual precipitation, and with decreasing January temperature in the region of the mountain flora, and (ii) increased with altitudinal range in regions of temperate and thermophilous flora. Main conclusions We described, in quantitative terms, the effects of the main factors that might be considered to be determining plant species richness in temperate nature reserves, and evaluated their relative importance. The direct habitat effect on species richness was roughly equal to the direct area effect, but the total direct and indirect effects of area slightly exceeded that of habitat. It was shown that the overall effect of composite variables such as altitude or climatic district can be separated into particular climatic variables, which influence the richness of flora in a context-specific manner. The statistical explanation of richness variation at the level of families yielded similar results to that for species, indicating that the system of nature conservation provides similar degrees of protection at different taxonomic levels. [source] Sensitivity of different taxonomic levels of soil Gamasina to land use and anthropogenic disturbancesAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2010José Camilo Bedano 1The effect of taxonomic level on the sensitivity of bioindicators has been widely investigated in aquatic ecosystems and, to a lesser extent, in terrestrial ecosystems. However, no studies have been conducted on the sensitivity of the different taxonomic levels of soil mites, especially Gamasina, to human activities. 2The present study aimed to assess the sensitivity of different taxonomic levels of soil Gamasina mites to anthropogenic disturbances in Europe and Argentina. We arranged the data from previous projects in a hierarchical system and conducted a study to identify the critical taxonomical levels that had the highest discriminative potential between sites (Europe and Argentina) or management types (forests, grasslands, fallows, succession, recultivation and agricultural sites). 3For the Gamasina community, geographical location was by far more important than the influence of any land use type. The analysis including only the European sites demonstrated that communities belonging to sites subjected to different land uses were also significantly different. 4The species data set provided a clearer separation of sites according to both the geographical and the land-use gradients than the genus and family data sets. The genus and, to a lesser extent, the family approach may be sufficient to elucidate the influence of great geographical differences and also of certain land uses (e.g. grasslands from the forests and arable sites). 5Species presence/absence data provided valuable information in our analyses, although the use of quantitative data yielded a clearer separation of sites. [source] Abundance,body mass relationships among insects along a latitudinal gradientAUSTRAL ECOLOGY, Issue 3 2008NIGEL R. ANDREW Abstract We investigated the relationship between abundance and body size (body mass) of 162 insect herbivore species on the host plant Acacia falcata along its entire coastal latitudinal distribution (eastern Australia), spanning a gradient in mean annual temperature of 4.3°C. We extend previous research by assessing these relationships at different spatial scales (latitudes pooled, among latitudes and within latitudes) and at different taxonomic levels (insect phytophages pooled, phytophagous Coleoptera and Hemiptera, and five component suborders/superfamilies). Insect species were collected from two orders (Hemiptera and Coleoptera) and five component suborders/superfamilies. There were no consistent trends in the relationships (linear or polygonal/hump-shaped) between abundance and body mass when latitudes were pooled, among latitudes, or when phytophagous insect species were separated into their component suborder/superfamily groups. The reason for the lack of consistent trends might be due to the insect herbivores not fully exploiting their host plant and the relative absence of competition among herbivore species for food resources. This is further assessed in relation to the lack of a consistent pattern in species richness of Coleoptera and Hemiptera herbivores from the same dataset and rates of chewing and sap-sucking herbivory along the same latitudinal gradient. Future studies of abundance,body size relationships are discussed in relation to sampling across environmental gradients and accounting for the influence of host plant identity and insect phylogeny. [source] Phytoliths of Indian grasses and their potential use in identificationBOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2000S. KRISHNAN Phytoliths are amorphous silicon dioxide (SiO2.nH2O) inclusions abundant in leaves, in-ternodes and glumes in members of Poaceae. They may occur as inclusions filling the entire lumen of the silica cells, bulliform cells and trichomes or may be part of the outer epidermal cell walls. Since phytoliths are resistant to fungal or animal digestive juices, a large quantity of phytoliths accumulate in the soil where grasses grow. Compared with the pollen grains of grasses which tend to be uniform, phytoliths vary in sue and morphology and can be of value in identification at different taxonomic levels and in the dating of past vegetation. The size and shape of phytoliths of about 100 species of grasses from Tamil Nadu, India, have been determined. Silica bodies were observed either after isolation or in cleared leaf blades. Size and shape of phytoliths were determined under a microscope or from micrographs of the specimens. Size and shape can be used to assign the phytoliths to their respective subfamilies and to distinguish some of the grasses at the generic level. Drawings of silica cells and an identification key are provided for 80 species. [source] | ||||||||||