Document Type : Research Paper
Authors
1 1Department of Medicinal Plants, Faculty of Agriculture and Natural Resources, Arak University, Arak 38156-8-8349, Iran.
2 Department of Plant Biology, School of Biology, College of Science, University of Tehran, Tehran, Iran
3 1Department of Medicinal Plants, Faculty of Agriculture and Natural Resources, Arak University
Abstract
Background and Objectives: Climate change poses a significant threat to biodiversity and the distribution of plant species. Allium jesdianum (Piaz-e-Yazdi), a valuable medicinal species in the Zagros Mountains of Iran, has populations that have been damaged by climate change and over-harvesting. This study aimed to identify the most critical environmental factors affecting the distribution of this species and to predict the impact of climate change scenarios on its future habitats.
Materials and Methods: This study employed Maximum Entropy (MaxEnt) modeling to predict the geographical distribution of A. jesdianum. Species occurrence data were used along with a set of bioclimatic, soil, and topographic variables. The impact of climate change on the species’ distribution was assessed under two scenarios, semi-optimistic (RCP 4.5) and pessimistic (RCP 8.5), for the years 2050 and 2070.
Results: According to the percent contribution index, the results indicated that elevation (55.4%), precipitation of the driest month (15.6%), and topsoil bulk density (13.1%) were the most decisive factors in the species’ distribution. The model, which demonstrated excellent performance (AUC = 0.9), predicted that the area of suitable habitats for this species will decrease by 14% to 23% under future scenarios, with the most severe decline occurring in the pessimistic scenario. Furthermore, suitable habitats are projected to shift towards higher latitudes (33° to 38° N), while suitability is expected to decrease at lower latitudes.
Conclusion: The findings of this study emphasize the necessity of adopting immediate conservation strategies for A. jesdianum. It is recommended that current and future suitable areas be identified and managed for In-situ conservation, as well as for the sustainable cultivation and utilization of this valuable species.
Keywords: Allium jesdianum, Climate change, Conservation, Iran, MaxEnt.
Materials and Methods: A suite of novel methods for examining the geographic distribution of species under various global warming scenarios was employed. In this framework, species distribution models (SDMs) have proven invaluable in predicting and understanding the distribution of plant species in the future, demonstrating significant effectiveness in conservation planning and management. The maximum entropy (MaxEnt) model is a specialized tool for assessing the ecological requirements of species, responding to environmental variables, habitat suitability, and changes in species ranges under different climate change scenarios. The MaxEnt modeling approach was used to identify the most important variables influencing the distribution of this species and to assess the impact of climate change under two representative concentration pathways (RCPs): RCP 4.5 (a relatively optimistic scenario) and RCP 8.5 (a more pessimistic scenario) for the years 2050 and 2070. All modeling processes were conducted in the R programming environment, and the output maps were prepared using Arc-GIS software.
Results: The results indicated that, based on the percentage contribution index, the most important factors influencing the distribution of A. jesdianum were, in descending order: elevation (55.4%), precipitation in the driest month (15.6%), topsoil bulk density (13.1%), precipitation in the wettest season (7.3%), topsoil organic carbon content (7.1%), and annual mean temperature (1.5%). The model performance, as assessed by the area under the curve (AUC), was excellent (AUC = 0.9). According to the modeling results, the distribution range of this species will decrease in all climatic scenarios in the coming years, with a reduction ranging between 14% and 23%. However, the pessimistic scenarios have the most negative impact on the distribution of the species. Additionally, climate change altered the habitat suitability across the geographic range, with the greatest reduction in suitable habitats predicted at latitudes between 28 and 32 degrees, while habitat suitability is expected to increase at higher latitudes of 33 to 38 degrees compared to current conditions.
Conclusion: The findings of this study can inform the selection of conservation approaches in the face of climate change for this species. Therefore, to minimize the negative impacts of climate change on the distribution of A. jesdianum, it is recommended that this species be included in in-situ conservation areas and that suitable regions be identified for its cultivation and utilization.
Keywords
Main Subjects
)