Regional climate–harvest relationships in Sweden 1818–1870

Here we present one of the most comprehensive high-quality datasets of 19^th century harvests in all of Europe—consisting of harvest yield ratio series of all the main crops from all 24 counties in Sweden during the period 1818–1870. Hierarchical cluster analysis reveals that a distinct regional structure in harvest variations, with coherent regions in northern, central-eastern, central-western, south-eastern, and south-western Sweden. However, the largest difference is that between the five northernmost counties and the rest of Sweden, reflecting the division into a growing season-temperature constrained agrometeorological zone in northern Sweden (approximately two-thirds of Sweden by area) and a corresponding zone based on the remaining regions in southern Sweden mainly dependent on summer soil moisture availability. Adjusting the harvest data by grain quality (weight) shows how variations in quality mainly mattered for northern of Sweden, where accounting for quality significantly increased the coefficient of variation.

Harvest yields of spring-sown crops (oats, barley, mixed-grain, legumes) were negatively correlated with mean June–August temperatures and positively associated with summer precipitation in the central-eastern, central-western, south-eastern and south-western Sweden, whereas harvest yields of all crops in northern of Sweden benefitted from warm springs and summers. These agrometeorological dependencies of spring crops are consistent with various other studies covering different periods from the late 17^th century to the early 21^st century (Edvinsson et al. 2009; Skoglund 2022, 2023, 2024; Ljungqvist et al. 2023; Sjulgård et al. 2023; Skoglund & Ljungqvist, 2026, in revision). Winter wheat yields were positively correlated with mean January–April temperatures in central-eastern Sweden, whereas harvest yields of winter cereals in the south-western and south-eastern Sweden shows a closer positive association with temperatures during and after sowing in the preceding August–October. Potato yields show a positive correlation with mean May–July temperatures in all of Sweden except the counties in the south bordering the Baltic Sea.

 

References

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