A DENDROCLIMATIC RECONSTRUCTION OF APRIL-JULY MEAN TEMPERATURE VARIATION IN THE MIDDLE ATLAS, MOROCCO, SINCE 1776 AD

Author Name: 1. R. Ilmen 2. W. Hammoudy

Volume/Issue: 03/04

Country: Morocco

DOI NO.: 08.2020-25662434 DOI Link: https://www.doi-ds.org/doilink/10.2022-31321158/UIJIR

Affiliation:

1. The Hassania School of Public Works (EHTP)
2. The General Directorate of Meteorology (DGM), Casablanca. Morocco

ABSTRACT

In Morocco, high-resolution tree-ring records covering the last hundreds years are very scarce, yet essential for understanding the process and pattern of climate change and designing climate model. In this paper, an Atlas Cedar (Cedrus atlantica M.) ring- width chronology spanning 1796-2011 AD and 1776-2011 AD was developed using standard dendroclimatological methods in two forest sites designed Tafechna and Ouiouane, respectively, at the Middle Atlas Mountains located in Khenifra province, Morocco. Trees in the second site are the oldest and strongly negative relationships were detected between the ring-width chronology and the monthly mean temperatures from June during the previous season to September during the growing season in this site. Based on correlation analysis, the mean temperature from April to July was reconstructed back to 1776 AD using a regression linear model. Therefore, 34% of the variance in temperature is reconstructed by this model. The reconstructed climate records show several alternating periods of high and low temperatures. Many of these hot years have been recorded to coincide with most of the known principal drought years of Morocco. The analysis of spatial correlation with the overall climate data, and comparisons with other temperature reconstructions based on tree rings surrounding areas, revealed that our reconstruction represented a regional variation on a larger scale temperature in the Middle Atlas region. Significant correlation between tree ring and climate is implying the possible influence of North Atlantic Oscillation (NAO) on the local climate. Considering the strong and negative between tree growth and temperature relationship, future warming will likely cause drought which will influence negatively the growth of trees as seen during the recent climate change experienced by Morocco since 1979. However, due to the limit of cedar age, the reconstruction couldn’t save the changes to the millennial scale which requires the development in the future of long time series of tree rings in Morocco

Key words: Climate change, Cedrus atlantica M., ring width chronology, temperature reconstruction, Morocco