Document Type : Research Paper

Authors

• Nasim Shaabani ¹
• Farhad Aghajanloo ²
• Nafiseh Salahi Moghadam ³
• Peyman Akbarzadeh ⁴
• Mehdi Khoshbakht ⁵

¹ Researcher, Forests and Rangelands Research Section, Zanjan Agricultural and Natural Resources Research Center, AREEO, Zanjan, Iran

² Assistant Professor, Forests and Rangelands Research Section, Zanjan Agricultural and Natural Resources Research Center ,AREEO, Zanjan, Iran

³ Researcher, Economic, Social and Extension Research Section, Zanjan Agricultural and Natural Resources Research Center, AREEO, Zanjan, Iran

⁴ Researcher, Forests and Rangelands Research Section, Zanjan Agricultural and Natural Resources Research Center, AREEO, Zanjan, Ira

⁵ Watershed Management Expert, Hamadan General Directorate of Natural Resources, Forests, Rangelands and Watershed Management Organization, Hamadan, Iran

Abstract

Abstract
Background and Objectives
Climate change is emerging as one of the main threats to the habitats and distribution of native plants. These changes can have widespread effects on the distribution of plant species. The T. persicus species T. persicus is found only in certain areas of northwestern Iran and is at risk of extinction for unknown reasons. This study uses the maximum entropy (MaxEnt) model to predict the effects of climate change on the distribution of T. persicus in northwestern Iran. The aim of this research is to assess the possible effects of climate change on the habitats of this species and identify areas that may be under serious threats.
 
Materials and Methods
In this study, Mahneshan County, Zanjan Province and Takab County, West Azerbaijan Province, located in the northwest of Iran, were selected as study areas. To determine the locations of the T. persicus species, 70 presence sites were randomly classified and selected based on the vegetation typology map of the provinces, which were used as training data for modeling. Also, to evaluate the model, 70 actual presence sites were collected in the field using the Global Positioning System (GPS) in July 2024 in the Mahneshan areas of Zanjan Province (the area of the directions of the Belghis Peak) and Takab County, West Azerbaijan Province. To model the distribution of this species, 30 environmental variables including 19 climate variables were used in three time periods of the present 2024 (1990–2020), 2070 (2060–2080) and 2100 (2080–2100) under the SSP585 and SSP126 scenarios and the IPSL-CM6A-LR general circulation model, 3 physiographic variables (elevation, slope and slope direction) as well as 8 soil physical and chemical variables. All environmental data were prepared with ArcGIS 10.8 software at a scale of 30 seconds (about one square kilometer). Finally, the maximum entropy model (MaxEnt) was used to model the distribution of the T. persicus species.
 
Results
Current distribution maps of this species were prepared with climate data under the two SSP585 and SSP126 scenarios, along with soil and physiographic data. Comparison between the effect of soil and climate data on distribution prediction, using the AUC index, showed that soil data (AUC=0.85) have a lower effect on predicting the distribution of this species. This could be due to the lack of access to data such as lead and zinc contamination of the region, which did not enter this information into the model. However, these elements can have a great impact on the distribution of this species due to the location of the T. persicus  species near the Angouran lead and zinc mine. Subsequently, future distribution maps of the species for the years 2070 and 2100 were prepared using climate and physiographic data. The model results showed that the most important variables affecting the distribution of the studied species include altitude, Bio1, Bio10, Bio11, Bio6, Bio12, Bio17, Bio18, Bio5, and slope. Also, according to the results obtained, T. persicus had a more effective distribution in areas with annual rainfall of 300 to 500 mm, altitudes above 2500 m, temperatures below 8 ° C and slopes above 20 °.
 
Conclusion
The results of modeling the distribution of the T. persicus species under the SSP126 and SSP585 scenarios indicate a significant reduction in the area of favorable areas for the growth of this species in the future. Currently, the area of the favorable area (with a best threshold of 0.3) is about 550.4 km2, which will decrease to 377.4 km2 under the SSP126 scenario and 252.2 km2 under the SSP585 scenario in 2070. In 2100, this decrease will be further and the area of the favorable area will reach 181.2 km2 (SSP126) and 93.9 km2 (SSP585). These changes indicate the negative effects of climate change on the distribution of the Persian thyme species and highlight the need for conservation measures to preserve this species against threats from climate change.

Keywords

• Climate Change
• Favorable Habitat
• Maximum Entropy
• T. Persicus