this research investigates the vegetation of 4600 ha of polour semi-steppe rangelands in relation to edaphic and physiographical parameters in mazandaran province. for this purpose, 23 land units were selected from overlaying slope, aspect and elevation maps using geographic information system (gis). within each unit, 3 parallel transects with 100 m length, each containing 10 quadrates (accordi...

Constrained ordination methods include constrained (or canonical) correspondence analysis (CCA), redundancy analysis (RDA) and distancebased redundancy analysis (db-RDA). Constraining means that ordination only shows the community variation that can be explained by external environmental variables or constraints. This document describes the following basic concepts (1) usage of constrained ordi...

We provide algebraic simplifications for the redundancy analysis (RDA) eigenvalue and the canonical correspondence analysis (CCA) eigenvalue in the special case of permanent plots sampled twice. The indices for RDA and CCA are interrelated and are intuitively interpretable. These simplifications also apply to simple split-plot designs and to a balanced design with two independent samples.

We present a new multivariate technique for testing the significance of individual terms in a multifactorial analysis-of-variance model for multispecies response variables. The technique will allow researchers to base analyses on measures of association (distance measures) that are ecologically relevant. In addition, unlike other distance-based hypothesis-testing techniques, this method allows ...

Macroalgae are considered as primary producers in ecosystem food chain. This study investigated spatial and temporal variation of three species of macroalgae namely, Laurencia caspica (red macroalga) Enteromorpha intestinalis and Cladophora glomerata (green macroalgae) on the hard substrates of the southern Caspian Sea coasts and their relation with environmental factors. Seasonal sampling pref...

Air sampling was conducted in Szczecin (Poland) throughout April-September 2013. The final data set included 177 daily and 4248 hourly samples. The total of 21 types of spores, which occurred in a number >10 in the season, were taken into account. The following meteorological parameters were analyzed: air temperature, relative humidity, precipitation and wind speed. Effects of individual weathe...

We investigated the diversity and community composition of denitrifying bacteria in surface water from the Yellow River estuary. Our results indicated that the diversity of the denitrifying community in freshwater based on the nirK gene was higher than that in seawater. Furthermore, phylogenetic analysis suggested that the bacteria community could be distributed into eight clusters (Clusters I ...

the effect of environmental factors on plant vegetation is different. therefore, it is necessary to evaluate role of these factors in medicinal plants growth, development and essential oil. this study was performed to investigate the effect of factors on qualitative and quantitative variations of the essential oil of verbascum songaricum in its habitats in central zagros mountains, iran in 2012...

Aiming to elucidate whether large-scale dispersal factors or environmental species sorting prevail in determining patterns of Trichoptera species composition in mountain lakes, we analyzed the distribution and assembly of the most common Trichoptera (Plectrocnemia laetabilis, Polycentropus flavomaculatus, Drusus rectus, Annitella pyrenaea, and Mystacides azurea) in the mountain lakes of the Pyr...