Modeling the effects of climate change on the potential distribution of the rangeland species Gymnocarpus decander Forssk (case study: Arid region of southeastern Iran).

Abstract

The phenomenon of climate change is the biggest environmental challenge in the world. Climate is a determinant factor in species distribution, and climate change will affect the species' abilities to occupy geographic regions. In this study which was conducted in May of 2019, spatio-temporal changes in potential habitats of Gymnocarpus decander were assessed using the MRI-CGCM3 climate change model for RCP2.6 and RCP8.5 scenarios for the near future (2041-2061) and far future (2061-2080) periods for this purpose, climatic variables of 24 synoptic stations across a case study, bio-climatic data and vegetation cover maps of G. decander were used. First, using the factor analysis process, the dimensions of the station-observed climatic variables were reduced to five factors with a total variance of 88.3%. Then, the region was divided into five homogeneous climatic regions using partitional clustering analysis. In this study by using the logistic regression modeling technique, the probability of the presence of the desired species for two groups of independent variables including climatic factors and bioclimatic variables in each of the groups was modeled. The results showed that the best models for determining the potential habitats of G. decander are logistic regression models in groups with independent bioclimatic variables. According to the results obtained from both scenarios, the habitats of G. decander species will decrease in the future. In the most optimistic case, about 8% of G. decander habitats will be lost by 2060 and about 12% by 2080. According to modeling results, currently, 48.2% total area of the region under study has a high potential for the presence of G. decander. Also, results indicate that region number 4 in this study with an altitude range of about 800-1250m, 16°C average temperature in the growing season and annual precipitation around 150-170mm is the major habitat for G. decander. According to climate change under the RCP2.6 scenario, the area of potential habitats of G. decander will decrease to 40% in the near future and 36.4% in the far future; and according to climate change under the RCP8.5 scenario, the area of potential habitats of G. decander will decrease to 23.9% in the near future and 32.5% in the far future. In the far future, because of the increase in total precipitation, some of the lost potential habitats during the near future will be suitable again for G. decander. Due to its stability in harsh environmental conditions, G. decander appears as a type-forming species in a wide range of natural habitats in the study area and is therefore important in terms of soil protection and forage production.