No abstract

A considerable proportion of Iran's territory is covered with arid and semi-arid rangelands and mismanagement and overexploitation of those rangelands have resulted in serious ecological degradation. Thus, the need is pressing to examine the present species composition and the relationships with environmental factors for providing the needed scientific references to species conservation and ecological rehabilitation efforts. The aims of this study were to examine the species composition and to delineate the most important factors influencing the distributions of plant species and groups in the northern rangelands of Isfahan Province (Iran) using two-way indicator species analysis (TWINSPAN), detrended correspondence analysis (DCA), principal component analysis (PCA), and canonical correspondence analysis (CCA). Field investigations were conducted in the growing season of 2014 using stratified random method in 22 homogeneous sampling units. In total, 75 plant species belonging to 52 genera and 19 families were identified. The most important families were Asteraceae and Papilionaceae, the most important genera were Astragalus, Cousinia, and Acanthophyllum, and the most important species were Artemisia aucheri and Artemisia sieberi. Plant species were classified into 10 groups using TWINSPAN. DCA was used to estimate the magnitude of changes in species composition along the first two ordination axes to provide gradient length estimations for PCA and CCA ordinations. The first three PCA axes and the first three CCA axes demonstrated similar cumulative percentage of variance, indicating that the environmental factors (selected by PCA) used in CCA ordination were acceptable for explaining the species composition and the distributions. CCA ordination showed that the first axis was closely related to elevation, slope, surface bare soil cover, surface litter cover, gravel proportion, organic matter, total nitrogen, CaCO 3 content, and grazing intensity and that the second axis was closely related to sand proportion, silt proportion, clay proportion, and saturation percentage. Among these factors, elevation was the most effective factor to separate the plant groups and grazing was the major cause of rangeland degradation.

Microrelief (MR) and water-table (WT) severely influence plant communities formation and development in silty loam saline soils of coastal areas. This research aimed to investigate the effect of MR and WT fluctuations on the dynamics of vegetation in coastal silty loam saline soils of southern Iran. Soil characteristics, vegetation structure and composition were investigated through the growing season, and obtained data were submitted to a canonical correspondence analysis. Based on the results, MR (min = 0.5 m and max = 1.0 m) and WT (max = 1 m) fluctuations significantly changed both structure and floristic composition through change in soil characteristics (Sig. < 0.05). Factors of soil moisture content, SAR and Na severely changed under MR and WT fluctuations and received new eigenvalues through the year. Our results demonstrated that a minimum change in MR and/or WT influence soil properties and vegetation structure and composition in silty loam saline soils of coastal areas.

The establishment of local communal organizations is a unique strategy of rural communities to build resilience against economic challenges. Shirvareh is traditionally recognized as an important communal organization of women in Southwestern Iran for managing dairy production and securing their livelihood. Preserving this vital social institution and its associated indigenous knowledge was the main motivation of this study to examine factors influencing Shirvareh's performance. Given that relevant studies on the performance of this social organization in Iran are rare, the current study was an attempt to fill this gap through an empirical study using a social network analysis (SNA) approach. The general goal of this study was to investigate the networks of trusting relationships of rural women involved in the Shirvareh organization in Ghasr-e-Yaghoub village located in Fars province, Southwestern Iran. The results revealed that possible in-group trust ties were maximum