Global Climate Pattern Impacts on Long-Term Olive Yields in Northwestern Africa: Case from Souss-Massa Region

Abstract

In arid to semi-arid regions, vulnerability to climate change combined with the overexploitation of water resources is jeopardizing food security. In the Souss-Massa region in central Morocco, the rural population relies on growing olives for a living. The management of these orchards is mostly traditional under rainfed irrigation, which induces a high level of dependence on climate variability. In the present study, we investigate the long-term trends of the relationship between the observed olive yields and global climate patterns during the period 1973–2014. We apply lagged Spearman’s correlations and cross-wavelet analysis to detect the potential influence of El Niño-southern oscillation (ENSO), the Indian Ocean Dipole (IOD), North Atlantic oscillation (NAO) and Pacific decadal oscillation (PDO) on the yield variability of olive orchards. The results of a Mann-Kendall test show a statistically significant decreasing trend in olive yields during the studied period. Statistically significant negative correlations were observed for (lag = −1) with spring and summer NINO 3.4 and with summer and autumn PDO. No statistically significant correlations between olive yields and NAO and IOD were observed. The results of wavelet coherence between annual olive yields and PDO and ENSO revealed that the highest values of power spectrum coherence occurred during the (lag = 0) spring PDO and (lag = −1) spring ENSO, both with an antiphase relationship. During the studied period, the extreme events of El Niña and El Niño years corresponded to below average yields.

The Effects of Atmospheric Oscillations on Crop (Olive, Grape and Cotton) Yield in the Eastern Part of the Mediterranean Region, Turkey

“…In this study that determined the relationship between olive yield and El Nino and NAO in Turkey, no significant relationship was found with NAO, but significant relationship and low yield was found in strong El Nino years (Uzun and Ustaoğlu, 2019). Another study that found statistically significant relationships between olive yield and Nino 3.4 indicewas applied in Northwest Africa (Abahous et al, 2021). It has been determined that there are significant statistical relationships between olive yield and Nino 3.4 in Iran (Bannayan et al, 2011).…”

“…This effect of atmospheric oscillations on climate is also observed directly on crops (Gimeno et al, 2002;Zubair 2002;Fraisse et al 2008;Soler et al 2010;Bannayan et al, 2011;Rao et al, 2011;Abdolrahimi, 2016;Capa. -Morocho et al, 2014;Iizumi et al, 2014;Gutierrez, 2017;Rojas et al, 2019;Uzun and Ustaoğlu, 2019;Qian et al, 2020;Abahous et al, 2021). Olive (Olea europaea L.) is a member of the maquis community included in the vegetation of the Mediterranean Climate.…”

The Effects of Atmospheric Oscillations on Crop Yield in the Mediterranean Region, Turkey

“…In the study that determined the relationship between olive yield and El Nino and NAO in Turkey, no significant relationship was found with NAO, but significant relationship and low yield was found in strong El Nino years (Uzun & Ustaoğlu, 2019). Another study that found statistically significant relationships between olive yield and Nino 3.4 indicewas applied in Northwest Africa (Abahous et al, 2021). It has been determined that there are significant statistical relationships between olive yield and Nino 3.4 in Iran (Bannayan et al, 2011).…”

“…This effect of atmospheric oscillations on climate is also observed directly on crops (Gimeno et al, 2002;Zubair 2002;Fraisse et al 2008;Soler et al 2010;Bannayan et al, 2011;Rao et al, 2011;Abdolrahimi, 2012;Capa. -Morocho et al, 2014;Iizumi 2014;Gutierrez, 2017;Rojas et al, 2019;Uzun & Ustaoğlu, 2019;Qian et al, 2020;Abahous et al, 2021).…”

Climate change alters impacts of extreme climate events on a tropical perennial tree crop

“…During the main cocoa purchase period, coinciding with the minor wet and major dry seasons, we observe increases in water deficit during El Niño, leading to drought stress conditions. In small-scale cocoa studies, drought stress is correlated with reduction in pod production and increased tree mortality 8,19 , and in similar studies of other tree crops drought is directly linked to reduction in fruit or nut production 20 , although in all cases the mechanisms are unclear. Drought may generally create unfavourable conditions for growth and reproduction through reduced availability of water for vital processes, or more specifically by promoting disease incidence and pod rot 8 , increasing the chance of fire, increasing competition for soil moisture 19 , and/or reducing pollinator populations 21 .…”