نتایج جستجو برای: cca ordination
تعداد نتایج: 7970 فیلتر نتایج به سال:
Insight into the relationship between plants and environmental characteristics is essential for managing rangeland ecosystems. The present study investigate the effect of soil and topographic factors on the distribution of the most important medicinal plants in Khosh Yeilagh Golestan province. Parameters such as density, frequency and canopy percent were the subjects of the study. Random-system...
Canonical Correspondence Analysis (CCA) is an increasingly popular method for multivariate analysis of ecological community data. It is, however, one of the most potentially misleading multivariate methods for community analysis. Inclusion of noisy or irrelevant environmental variables can distort the representation of gradients in community structure. These hazards are illustrated with simulat...
As band widths are narrow and range of spectra is wide, subtle differences in spectral features can be extracted and used for mapping physical and chemical properties of bare substrate with imaging spectroscopy. However, the use of spectral characteristics of substrates is not accessible if substrate was covered by vegetation. In this study, we explored the feasibility of extracting karst ecoen...
The distribution of macroinvertebrate communities from 5 sampling sites of the Tajan River were used to examine the relationship among physiochemical parameters with macroinvertebrate communities and also to assess ecological classification system as a tool for the management and conservation purposes. The amount of variation explained in macroinvertebrate taxa composition is within values r...
Abstract This paper presents a quantitative account of vegetation–environmental factor relationships in arid rangelands. Vegetation cover was recorded using Braun-Blanquet combined abundance-cover scale in each quadrat. Within each quadrat, one profile was dug and soil samples being taken at 0-20cm and 20-100cm depths. Under study physical-chemical characteristics included texture, lime, orga...
Dynamic of sandy alpine grasslands affect the progress and reversal desertification in source regions Yangtse Rivers. To understand geomorphic driving mechanism species distribution pattern, we examined compositions delineated most important landform factors influencing grassland using two-way indicator analysis (TWINSPAN), detrended correspondence (DCA), canonical (CCA). Field survey were cond...
Macrophyte species and trait assemblages from 104 minimally disturbed boreal forest lakes, covering broad environmental geographic gradients were analysed to identify associations with variables at different spatial scales: context (GEO) catchment (CATCH) lake (LOCAL) characteristics.Constrained ordination variation partitioning used quantify in (canonical correspondence analysis [CCA] pCCA) (r...
To assess the potential for enhancing an existing stand of native perennial grasses on a California Coast Range Grassland site, we experimentally manipulated the seasonal timing and presence of grazing for 3 years (1994 through 1996) and of autumn burning for 2 years (1994 and 1995) and measured species cover for 6 years (1993 through 1998). We subjected the species matrix to classification (TW...
The purpose of this study was to evaluate the species-environment relationships in arid and semi-arid rangelandsof Nodushan, Yazd. The plant species cover and the environmental variables were measured at 9 sites. Soil sampleswere taken for measurement of 12 attributes in 0-10 cm and 10-80 cm layers. Vegetation was classified using twowayindicator species analysis (TWINSPAN). Data was analyzed u...
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