Forecasting the current and future range of Bromus tomentellus Boiss species under two climate warning models (Rcp4.5 and Rcp8.5) in rangeland ecosystems of Ardabil province

Climate change has been a serious issue in the last two decades and many studies have focused on its various aspects. Therefore, it is necessary to determine the potential habitat of rangeland index species, currently and in the coming years, under climate warning models. Therefore, in the present study, by preparing a prediction map of the current and future range of Bromus tomentellus species, under two climate warning models (Rcp4.5 and Rcp8.5 scenarios), its movement, in latitudes, at the level of rangeland ecosystems of Ardabil province was investigated.

For this purpose, in the growing season of 2020, from 19 bioclimatic variables and three physiographic variables and a logistic regression model, to determine the quantity of climate change in the next three decades (2050) and to carefully examine its effects on the change in the range of B. tomentellus species now and in the future, used. The output maps are divided into four categories with the probability of occurrence between zero and one; unsuitable habitat (0-0.25), almost suitable habitat (0.25-0.5), habitat with high suitability (0.5-0.75) and habitat with very high suitability (0.75-1), it was grouped and based on the coefficients of the variables in the regression relationships, the effective variables for the current and future range were introduced.

The average annual temperature (BIO1), the annual temperature range (BIO7) and the average temperature of the coldest season (BIO11) are the most important for the suitability of the habitat, and their values increase with the harsher climatic conditions. The average annual temperature of its suitable habitats will increase by 1.6 to 2.1 degrees Celsius in the next three decades. The height of its suitable habitats will increase from 115 to 190 meters. As a result, the level of its suitable habitat decreases in response to climate change. Also, under climate scenarios, 30.2% of suitable climate habitats will be lost in 2050, and current unsuitable habitats will increase by 29.4%.

In general; climate change and increase in temperature will cause B. tomentellus species to move to higher latitudes along the altitude gradient. Therefore, in the next three decades, there is a risk of removing it from the rangeland ecosystems of Ardabil province.