Spatio-temporal analysis of hazelnut production and yield in Türkiye (1991–2022)

This study examines the dynamics of hazelnut production and yield in Türkiye between 1991 and 2022, based on long-term time series, spatial distribution, and regional comparisons. The findings reveal that fluctuations in production and yield have persisted, although a partial upward trend in production capacity has emerged in recent years. Spatial analyses confirm that the Black Sea belt remains the undisputed production core, while the Central Black Sea region, led by Samsun, has gained increasing importance. At the provincial level, Ordu, Giresun, and Sakarya stand out as key drivers of both total output and annual fluctuations. Overall, despite maintaining its global leadership, Türkiye’s hazelnut sector continues to face multidimensional challenges, including low productivity, regional imbalances, production volatility, and quality issues which result in income fluctuations for growers, inconsistent supply for processors, and difficulties in meeting stable quality and export requirements. Over the long term, Türkiye’s hazelnut production exhibits a clear upward trajectory. The average annual production increased from approximately 450 thousand tons in 1991–1999 to 559 thousand tons in 2000–2010, followed by a more moderate rise to 569 thousand tons in 2011–2019. A sharper growth pattern emerged in the recent period, with the average reaching 705 thousand tons in 2020–2022. Overall, these figures indicate a long-term increase of nearly 57% between the early 1990s and the early 2020s, reflecting structural improvements in production capacity despite year-to-year volatility. The relationship between yield and national production is weak (r = 0.11), indicating that structural factors such as fruit-bearing tree counts and orchard area play a dominant role. Methodologically, the study integrates long-term time-series techniques (moving averages, percentage change, rolling volatility, simplified CUSUM) with spatial mapping and province-level contribution analysis, providing a novel multi-dimensional assessment of Türkiye’s hazelnut sector over a 32-year period.