Fluctuations of winter wheat yields in relation to length of winter in Sweden 1866 to 2006

Abstract

The winter wheat Triticum aestivum L. areas in Sweden (55 to 61°N) are at, or close to, the northern border of winter wheat cultivation. Yield variations at the county level for 1866 to 2006 are analysed and compared with variations in length of winter. Yield deviations greater than ± 25% occur on average once every 5 yr in a county, but more often in the north. In a maritime climate such as the one in north-western Europe, the length of winter fluctuates considerably. Deviations in length of winter by more than ± 45 d appear on average once every 5 yr in a county, but more frequently in the southern coastal counties. However, freezing temperatures are also more intermittent there compared to the continuous cold in the north. By means of a cluster analysis of the variations in length of winter, the counties were divided into 4 groups. The general effect is that long winters give decreasing yields. Regressions between deviations in yield and length of winter show determination coefficients (R 2 ) in the range of 0.13 to 0.30, which is high for a single variable. Winters are, on average, 48 d longer when yields are 25% below trend compared with yields 25% above trend. This pattern seems to be typical for climates with winter temperatures < 5 to 6°C. KEY WORDS: Length of winter · Winter wheat yield · High latitude · Climate fluctuations Resale or republication not permitted without written consent of the publisherClim Res 36: [241][242][243][244][245][246][247][248][249][250][251][252] 2008 2002) and photoeffects beyond the end of the vegetative phase (Gonzalez et al. 2002).Very cold winters cause winter kill of seedlings. Temperatures of -20 to -15°C are lethal (Porter & Gawith 1999). However, snow cover gives protection, acting as an insulation layer. For example, with 10 cm of snow, the nighttime soil temperature minimum can be as high as -12°C, while the air temperature minimum is -30°C (Peel & Riveland 1997).Data on winter wheat yields in southern England for >100 yr (Chmielewski & Potts 1995) showed negative correlation with precipitation occurring in all months, i.e. there is more than enough water for the entire year. Negative temperature correlations also prevailed for most of the year, especially in July, which means that high temperatures were not favourable to yields. A significantly high correlation with maximum temperature in April was a notable exception, showing that higher temperatures in spring will encourage plant development after the winter. Landau et al. (1998Landau et al. ( , 2000, using more recent yield data from the entire UK, supported the adverse effect of precipitation and minimum temperature in July, but stressed the positive correlation with maximum temperature in January and diminished winter killing due to a fewer number of extreme frosts. Similarly, Olesen et al. (2000), in Denmark, showed a positive effect of a high temperature in October, November and January and a strong negative effect of too much precipitation in July. On the other hand, Alexandrov & Hoogenbo...

Changing regional weather-crop yield relationships across Europe between 1901 and 2012

“…As wheat and barley yields are limited in northern Europe by cool temperatures (Holmer 2008) and in southern Europe by high temperatures and low rainfall (Reidsma & Ewert 2008) it was hypothesized that the response to warming within these regions is likely to differ. Indeed, in Finland and Norway we found an increasing influence of temperature, and in Bulgaria and Tuscany of drought, after 1951 (Table 5).…”

Crop yield trends in relation to temperature indices and a growth model

“…However, at the county level, this decline was less clear (Fig. 3) Holmer (2008) suggested that winter length has a pronounced influence on yield at mean annual temperatures below 5 or 6°C, which corresponds to the climate of the Uppsala region (Table A2), in which yields were most influenced by winter temperatures in our study.…”

Snowed in for survival: Quantifying the risk of winter damage to overwintering field crops in northern temperate latitudes

“…Furthermore, overwintering crops provide some of the advantages of winter cover crops (e.g., reduction of soil erosion and nutrient leaching) without requiring the additional labor and expenses typical of cover crops. At the same time, overwintering crops are exposed to climatic vagaries for a longer period, with potentially negative impacts on winter survival rate, crop vigor, and hence final yields (Bergjord and Skjelvåg, 2011;Holmer, 2008;Licker et al, 2013;Peltonen-Sainio et al, 2011;Reinsdorf and Koch, 2013). It has long been understood that a range of conditions may damage overwintering plants (Salmon, 1917).…”