Studying edaphic and physiographic factors affecting plant diversity in semi-arid rangelands (Case study: Khangah-Sorkh rangeland, Urmia)

Document Type : Research

Authors

1 Graduated M.Sc. Student of Range Management, Faculty of Natural Resources, University of Tarbiat Modares, Noor, Iran

2 Faculty of Natural Resources, University of Tarbiat Modares, Noor, Iran

3 Faculty of Natural Resources, University of Urmia, Urmia, Iran

Abstract

Achievement of quantitative and qualitative parameters for rangeland vegetation such as plant diversity is essential for proper management. To study plant diversity indices, Khangah-Sorkh with an area of over 2000 hectares of rangeland watersheds in the range of 1400 to 2400 m elevation above sea level, in West Azarbaijan Province was selected. There are three plant types in the region with names of Astragalus microcephalus – Acanthophyllum microcephalum؛ Pteropyrum aucheri – Astragalus microcephalus؛ Pteropyrum aucheri – Prangus uloptera. In each type two key regions and in each key area, cover and soil sampling was conducted in 30 plots of 1‌m2. Then, the diversity of plant species was calculated using three richness indices (Simpson, Shannon - Weiner and Hill 1) and one evenness index (Simpson) in all key areas and the mean comparisons were used for statistical analysis of key areas. Tissue, nitrogen, organic carbon and soil pH were measured in key areas. To identify factors affecting plant diversity indices, multiple regression was used. Results showed that plant diversity in the first key region in the types of Astragalus microcephalus - Acanthophyllum microcephalum is higher than other regions. Studying the relationship between plant diversity with some soil and physiographic factors using multivariate regression analysis showed that elevation had negative effect on the considered plant diversity indices. The percent of hillside increased the mentioned factors which is probably due to the destruction and too pasture degradation and over-grazing on lower slopes and eliminating these destructive factors in the higher slopes.

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History

  • Receive Date: 17 November 2012
  • Revise Date: 18 March 2013
  • Accept Date: 20 April 2013

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