University of Guilan Caspian Journal of Environmental Sciences 1735-3033 22 3 2024 07 01 How is climate change impacting net primary production and reference evapotranspiration in the Zagros region of western Iran? 539 553 7692 10.22124/cjes.2024.7692 EN Pedram Attarod Department of Forestry and Forest Economics, Faculty of Natural Resources, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Omid Fathizadeh Ahar Colleges of Agriculture and Natural Resources, University of Tabriz, Tabriz, Iran 0000-0002-0696-7090 Parisa Abbasian Natural Resources Bureau of Alborz Province, Natural Resources and Watershed Organization of Iran, Karaj, Iran Vilma Bayramzadeh Department of Wood Science and Technology, Faculty of Agriculture and Natural Resources, Karaj Branch, Islamic Azad University, Karaj, Iran Curtis Holder Department of Geography and Environmental Studies, University of Colorado, Colorado, USA Qiuhong Tang Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research (IGSNRR), Chinese Academy of Sciences (CAS), Beijing, China Xingcai Liu Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research (IGSNRR), Chinese Academy of Sciences (CAS), Beijing, China Hamid Soofi Mariv Department of Forestry and Forest Economics, Faculty of Natural Resources, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Samira Beiranvand Department of Forestry and Forest Economics, Faculty of Natural Resources, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran Journal Article 2024 04 07 We assessed how climate change may impact net primary production (NPP) and reference evapotranspiration (ET₀) from the Zagros region of western Iran covered extensively by oak, -<em>Quercus branti</em> Lindl. forests. The daily meteorological parameters of temperature (T), precipitation (P), relative humidity (RH), wind speed (WS), and sunshine hours were obtained from 20 meteorological stations throughout the region over a 30-year period (1988-2017). Net primary production and ET₀ were estimated by the synthetic and the FAO Penman-Monteith models, respectively. A non-dimensional relative sensitivity coefficient was used to examine the sensitivity of NPP and ET₀ to changes in the meteorological parameters. The sensitivity analyses were carried out for T, P, and WS within a possible range of ± 10%, ± 30%, and ± 10%, respectively, from the long-term mean. Except for the P with no notable trend, other meteorological parameters exhibited upward or downward trends. The mean NPP and ET₀ values were estimated to be 6.5 t ha^-1 y^-1 and 3.9 mm d^-1 across the Zagros region, respectively. Net primary production was found to be more sensitive to precipitation with a sensitivity coefficient of 0.66 and less sensitive to temperature with a sensitivity coefficient of 0.40. The ET₀ sensitivity coefficients in response to T changes doubled relative to WS (0.33 against 0.63). Identifying the contributing factors in NPP and ET₀ trends is important for understanding the relative impacts of climate change and human activities in arid and semi-arid regions. https://cjes.guilan.ac.ir/article_7692_d18a9c93f02295daa26b7e937617362a.pdf