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University of Mohaghegh Ardabili (2018)

Study the structure of rangeland species composition and diversity in rangeland of Hir county

Porghorban, Nooshin

Titre : Study the structure of rangeland species composition and diversity in rangeland of Hir county

Auteur : Porghorban, Nooshin

Université de soutenance : University of Mohaghegh Ardabili

Grade : Master Thesis 2018

Résumé
The aim of this study was to investigate the composition and diversity structure of rangeland species influenced by environmental factors in Hir-Neor rangelands. Sampling was conducted in June 2016 in a randomized-systematic way on 11 sites and in three altitudinal profiles and at 330 plots. The poistion of each plot was recorded and in each plot, vegetation canopy cover and density, litter, bare soil were determined. Plant speciesmens were collected surface of plots and transmitted to Herbarium for identification. In each transect, soil samples were taken from depths of 0-30 cm of the soil surface. Biodiversity indices were calculated using PAST.5 software. SPSS.16 was used to investigate the significance and correlation of the analysis of variance by comparing the means and multiple regression. Minitab17 and CANOCO4 were used to determine the most important effective factors on species distribution. Location of the area, slope, aspect and elevation Maps were provided in GIS environment. Results showed that there is a significant relationship between the topgraphic factors and species diversity (p<0.01). The highest amount of diversity and richness species were calculated for altitude 1600 to 1850 m a.s.l. and the highest amount of diversity and richness for shrubs were calculated at 2100 to 2600 m. The highest species diversity was recorded at the slope ranges of 0 to 15%. The highest diversity and richness were observed in the southern and western aspects. The results of regression equations showed that the plant species density parameter is more affected by environmental factors than other parameters. The results of principal component analysis indicated that the first component has the highest correlation with the silt, organic carbon particle, particlate organic matter, organic matter, organic carbon variables, as well as the second component has the corrlation with altitude, annual temperature, annual precipitation, potassium and volumetric moisture variables. Detrended Correspondence Analysis analysis results showed that altitude, temperature, volumetric moisture, organic matter, organic carbon, silt, and potassium have the greatest effect on the composition and diversity of the study area. In general, it can be concluded that vegetation in the study area is influenced by a set of environmental factors that, by considering these variables and thier positive and negative effects, can apply better and proper management in order to conserve and maintain the biodiversity and vegetation.

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