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Introduction: In recent years, attention has been paid to the effects of global climate change on different species and ecosystems. Among these, three important issues of increasing air temperature, change in carbon dioxide concentration and nitrogen deposition in relation to environmental changes and the response of plants to them, have been widely studied in many places around the world. and is often related to climate change. Climate change can cause an increase in the growing season or a change in rainfall. The greatest effect of climate on tree growth can be seen in the width of annual tree rings. The formation of annual rings of a tree is affected by many different environmental and physiological factors, among which climate changes play a special role. The change in the growth and development of trees is one of the first reactions of trees to climate change. This study was conducted with the aim of monitoring the effect of climatic variables on the growth and distribution range of Pistacia atlantica tree species in Zagros forests in Ilam province using tree chronology.Materials and methods: For this purpose, sampling was carried out using an upgraded annunciator drill from 23 trees according to the extent of each climatic class using the Demartin method in Ilam province. After preparing the samples, the width of the annual vegetation rings was measured using Motic image software with high accuracy for a period of 30 years (1991 to 2022).Results: Based on the results of the average growth of each station, it was determined that Haft Cheshme station located in the Mediterranean climate class of Dumarten with an average growth of 1.13 mm has the highest growth and Manshet station located in the semi-humid climate class of Dumarten with an average growth of 0.83 has the lowest growth. In general, regions with Mediterranean climate have higher growth rate and semi-humid and semi-arid climates are in the next ranks respectively. Meteorological data from WorldClim station were used to understand the relationship between growth and climate. The Pearson correlation results of climatic variables with the growth of Bene species in the sampled stations showed that in the semi-arid climate, with the decrease in altitude above sea level, diameter growth has the highest correlation with the average maximum temperature variable, and with the increase of altitude above sea level, it has the highest correlation with the variable Precipitation is dependent, and in the Mediterranean climate, growth in higher areas has the highest correlation with the variable of precipitation, and with the decrease in altitude, growth is dependent on the average maximum temperature variable. Also, in semi-humid climates, growth has the highest correlation with the average maximum temperature variable, and with the increase in altitude The degree of correlation decreases from sea level.Discussion: The results show that the growth of areas with an altitude higher than 1700 and an altitude lower than 1000 is more affected by the average maximum temperature, and the changes in the maximum temperature are the main factor limiting the distribution of Beneh species in Ilam province, so that with the increase in temperature, the species moves towards the heights. And the regions with Mediterranean climate will migrate to reduce the effects of the maximum temperature factor, and as a result, with the passage of time, the distribution range of Beneh species will also decrease in these borders. |
