اولويت بندي خطر گونه هاي گياهي مهاجم در مراتع استپي و نيمه استپي جنوب‌غربي اصفهان با استفاده از رويكردهاي مدل‌سازي چند معياره و پراكنش گونه اي

Invasive plant species are among the most significant threats to rangelan‎d ecosystems, as they can alter vegetation structure, reduce biodiversity, an‎d cause substantial ecological an‎d economic impacts. This study was conducted to assess the risk of invasive plant species, identify the environmental factors affecting their distribution, model their potential ecological niches, an‎d prioritize their invasion risk in the steppe an‎d semi-steppe rangelan‎ds of the southern part of Isfahan Province, Iran. The studied species included Cousinia cylindracea, Hulthemia persica, Euphorbia decipiens, Phlomis persica, Poa bulbosa, Gundelia tournefortii, Eryngium billardieri, Hertia angustifolia, an‎d Scariola orientalis. Vegetation an‎d soil sampling were carried out at 19 sites located in the southern counties of Isfahan Province, including Dehaghan, Shahreza, an‎d Semirom. Principal Component Analysis (PCA) was used to investigate the relationships between vegetation an‎d environmental variables, the MaxEnt model was employed to predict the potential distribution of species, an‎d the Analytic Hierarchy Process (AHP) was applied to prioritize species risk. The results indicated that the soils of the study area were predominantly alkaline, non-saline, an‎d characterized by relatively high calcium carbonate content, while available phosphorus levels were generally low to moderate. PCA results revealed that species distribution an‎d site differentiation were strongly influenced by a combination of edaphic an‎d climatic factors. Electrical conductivity, saturation percentage, total nitrogen, available phosphorus, calcium carbonate, precipitation-related variables, an‎d annual temperature fluctuations were identified as the main drivers of vegetation patterns. MaxEnt modeling demonstrated good to excellent predictive performance for most species. G. tournefortii showed the highest predictive accuracy, whereas Scariola orientalis exhibited the lowest. Habitat suitability maps indicated that the southern an‎d southwestern parts of the study area, particularly mountainous regions an‎d foothill zones, provide the most suitable habitats for the majority of the studied species. Annual temperature range (Bio4) an‎d precipitation of the coldest quarter (Bio19) were identified as the most influential climatic variables controlling species distribution. The AHP results showed that ecological impact was the most important criterion in determining species risk. Accordingly, Cousinia cylindracea was identified as the highest-risk species, while Poa bulbosa was ranked as the lowest-risk species. The remaining species were ranked, respectively, as H. persica, E. billardieri, S. orientalis, P. persica, G. tournefortii, H. angustifolia, an‎d E. decipiens. Sensitivity analysis confirmed the robustness an‎d stability of the ranking results. The integrated outputs of MaxEnt modeling an‎d AHP prioritization highlighted the southern an‎d southwestern parts of the region as potential hotspots for the spread of high-risk species, which should be prioritized for monitoring, prevention, an‎d management programs. Overall, the findings of this study provide a scientific basis for the effective management of invasive plant species an‎d the enhancement of rangelan‎d ecosystem sustainability in the study area.

حسين بشري , مصطفي تركش اصفهاني

رضا جعفري , سعيد پورمنافي