Forest and Wood Products

Forest and Wood Products

The effect of long-term trends of precipitation and consecutive dry days on Zagros forests decline in Ilam Province

Document Type : Research Paper

Authors
Somayeh Mirzaei
Pedram Attarod
Kimiya Mostafanezhad Nesheli
Department of Forestry and Forest Economics, Faculty of Natural Resources, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
10.22059/jfwp.2025.392721.1344
Abstract
The Zagros forests in Ilam Province, covering 0.64 million hectares, have been in decline for over two decades, with the index of consecutive dry days (CDD)—a key climate change indicator—identified as a contributing factor. We analyzed 35 years (1988–2022) of daily meteorological data from the Ilam synoptic weather station using the Mann-Kendall non-parametric test to assess trends in precipitation and CDD. The mean annual precipitation was 544 mm (SD = 173 mm) with no significant trend (ZMK = 1.46), though a notable decrease occurred from 605 mm before the onset of decline to 497 mm afterward (t = 1.98). On average, 313 (±12 SD) dry days occurred annually, with about 70% during spring and summer. Each year, 27 (±4 SD) dry spells were recorded, mostly under 30 days, but two typically exceeded that threshold (30 days). A significant rise in dry spells longer than 30 days was observed after the decline began (ZMK = +3.12). The mean maximum annual CDD reached 150 days, peaking at 219 days in 2021. These findings indicate that reduced precipitation and prolonged dry periods linked to climate change play a critical role in the ongoing decline of the Zagros forests in Ilam Province.
Keywords
Climate Change
Mann-Kendall test
Oak decline
Quercus brantii
Subjects
  • Alexander, L.V., Zhang, X., Peterson, T.C., Caesar, J., Gleason, B., Klein Tank, A.M.G., Haylock, M., Collins, D., Trewin, B., Rahimzadeh, F. & Tagipour, A. (2006), Global 3observed changes in daily climate extremes of temperature and precipitation. Journal of Geophysical Research: Atmospheres, 111(D5).
  • Attarod, P., Sadeghi, S. M. M., Taheri Sarteshnizi, F., Saroui, S., Abasian, P., Masihpour, M., Kordrostami, F. & Darikundi, A. (2015). The influence of climatic factors and evapotranspiration on the decline of the central Zagros forests in Lorestan province. Research on Support and Protection of Forests and Rangelands in Iran, 13(2), 97-112.
  • Attarod, P., Sadeghi, S. M. M., Pypker, T.G., & Bayramzadeh, V. (2017). Oak trees decline; a sign of climate variability impacts in the west of Iran. Caspian Journal of Environmental Sciences, 15(4), 375-386.
  • Attarod, P., Beiranvand, S., Asgari, M., Fanaei, N. & Hashemzadeh, M. (2021). The effects of rainfall fluctuations on declining Zagros Forests in Ilam and Lorestan provinces. Iranian Journal of Forest, 13(2), 141-154.
  • Attarod, P., Fathizadeh, O., Abbasian, P., Bayramzadeh, V., Holder, C., Tang, Q. & Beiranvand, S. (2024). How is climate change impacting net primary production and reference evapotranspiration in the Zagros region of western Iran?.Caspian Journal of Environmental Sciences, 22(3), 539-553.
  • Alizadeh, A. (2010). Principles of Applied Hydrology, Imam Reza University Press, 28th edition: p. 815.
  • Allen, C.D., Macalady, A.K., Chenchouni, H., Bachelet, D., McDowell, N., Vennetier, M. & Cobb, N. (2010). A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests. Forest Ecology and Management, 259(4), 660-684.
  • Azizi, M., Mohammadi, H. & Rezaei, A. (2018). Analysis of trends in dry periods in western Iran. Iranian Journal of Soil and Water Research, 50(3), 567-579.
  • Becker, S., Hartmann, H., Zhang, Q., Wu, Y. & Jiang, T. (2007). Cyclicity analysis of precipitation regimes in the Yangtze River Basin, china. International Journal of Climatology, 94, 139-153.
  • Beiranvand, A., Attarrod, P., Tavakoli, M. & Marvi Mohajer, M.R. (2015). Zagros forest ecosystem decline, causes, consequences, and remedies. Forest and Rangeland Journal, 106, 18-30.
  • Daşci, Y., Özkan, K. & Gülsoy, S. (2011). Seasonal changes of soil moisture in forest ecosystems: A case study in the Mediterranean region. Journal of Environmental Biology, 32(5), 567-572.
  • Frich, P., Alexander, L.V., Della-Marta, P., Gleason, B., Haylock, M., Klein Tank, A.M.G., Peterson, T. (2002). Observed coherent changes in climatic extremes during the second half of the twentieth century. Climate Research 19, 193-212.
  • Goodarzi, N., Zargaran, M.R., BanjShafiei, A. & Tavakoli, M. (2016). The effect of geographical directions and location on dispersion of Oak decline, Shurab forest area. Lorestan Province, Iran. Forest Research and Development, 2(3), 273-287.
  • General Department of Natural Resources and Watershed Management of Ilam Province (2014).
  • IPCC (2021). Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.
  • Jazireii, M.H. & Ebrahimi Rostaghi, M. (2003). Silviculture in Zagros. University of Tehran Press, Tehran, 560p. (In Persian).
  • Jafari, M.R., Hosseinzadeh, J., Pourhashemi, M., Norouzi, A.A., Mirakhorlou, Kh. and Mohammadpour, M., (2014). Identification and zoning of forest stands affected by oak decline using GIS & RS in Ilam Province. Final Report of Research Project, Research Institute of Forests and Rangelands, 48 p. (In Persian)
  • Hamzepour, M., Kiadeliri, H., & Bardbar, K. (2011). A preliminary investigation of the drying of Iranian oak trees (Quercus brantii Lindl.) in the Baram plain of Kazeroon, Fars province. Scientific-Research Quarterly Journal of Forest and Spruce Research of Iran, 19(2), 153-167.
  • Lotfi Nasab Asl, S., Dargahiyan, F., Gohardoust, A., Hatem Baharvand, A. & Razavi Zadeh, S. (2023). Analysis of drought status and Its relationship with climate change events (Case study: Oak decline sites in Sarableh, Ilam province). Iranian Journal of Rangelands and Deserts, 30(2), 335-354.‎
  • Lindnera, M., Maroschek, M., Netherer, S., Kremer, A., Barbat, B., Garcia-Gonzalo, J., Seidl, R., Delzon, S., Corona, P., Kolstro, M., Manfred, J., Lexerb, L. & Marchetti, M., (2010). Climate change impacts, adaptive capacity, and vulnerability of European forest ecosystems. Forest Ecology and Management, 259, 698-709.
  • Morgan, P., Hardy, C.C., Swetnam, T.W., Rollins, M.G. & Long, D. G. (2001). Mapping fire regimes across time and space: Understanding coarse and fine-scale fire patterns. International Journal of Wildland Fire, 10(4), 329-342.
  • Marvi Mohajer, M.R., (2011). Tehran University Press, third edition, 417 p. (In Persian).
  • Miner, B., (2004). Associated Dieback Strategy. Forest Ecology and Management, 214 (3-4), 24- 35.
  • Mousavi, S., Rahimi, M. & Alizadeh, A. (2020). Changes in drought patterns in western Iran. Iranian Journal of Soil and Water Research, 52(3), 456-467.
  • Pourhashemi, M., Jahanbazi Gojani, H., Hosseinzadeh, J., Bardbar, S.K., Iranmanesh, Y. & Khodakarami, Y. (2017). The background of oak forests decline in Zagros. Iranian Nature, 2(1), 30-37.
  • Pourhashemi, M., Masoumi, A.A., Marvi Mohajer, M.R., Sagheb Talebi, K.H., Ghasriani, F., Azizkhani, E., Parhizkar, P., Hosseinzadeh, J., Bordbar, S.K., Jahanbazi Goujani, H., Tavakkoli, M., Khodakarami, Y., Ebrahimi Rostaghi, M., Pourmoghaddam, K. & Khanjanzadeh, M. (2017). Control of the decline of Zagros forests depends on the implementation of the action plan. Journal of Iran Nature, 2(2), 14-19.
  • Papalexiou, S.M. & Montanari, A. (2019). Global and regional increase of precipitation extremes under global warming. Water Resources Research, 55(6), 4901-4914.
  • Ranjbar, A., Mohammadi, B. & Hosseini, S. (2020). Analysis of trends in dry periods in Ilam Province. Journal of Climate Research, 12(2), 45-60.
  • Sagheb Talebi, Kh., Sajedi, T. & Pourhashemi, M., (2014). Forests of Iran: A Treasure from the Past, A Hope for the Future. Springer, 152 p.
  • Sa’adi, Z., Shahid, S., Ismail, T., Chung, E.S. & Wang, X. J. (2019). Trends analysis of rainfall and rainfall extremes in Sarawak, Malaysia using modified Mann–Kendall test. Meteorology and Atmospheric Physics, 131(3), 263-277.
  • Zarrin, A. & Dadashi-Roudbari, A.A. (2021). Projected consecutive dry and wet days in Iran based on CMIP6 bias‐corrected multi‐model ensemble. Journal of the Earth and Space Physics, 47)3(
  • Zhang, X., Wang, S., Zhang, Y., Li, R. & Jiang, T. (2019). Changes in precipitation extremes over the dry and wet regions of China and their connections with global sea surface temperature. Journal of Climate, 32(12), 3723-3740.
Forest and Wood Products
Volume 78, Issue 1
Spring 2025
Pages 1-10