Decline in climate resilience of European wheat

Abstract

Food security relies on the resilience of staple food crops to climatic variability and extremes, but the climate resilience of European wheat is unknown. A diversity of responses to disturbance is considered a key determinant of resilience. The capacity of a sole crop genotype to perform well under climatic variability is limited; therefore, a set of cultivars with diverse responses to weather conditions critical to crop yield is required. Here, we show a decline in the response diversity of wheat in farmers' fields in most European countries after 2002-2009 based on 101,000 cultivar yield observations. Similar responses to weather were identified in cultivar trials among central European countries and southern European countries. A response diversity hotspot appeared in the trials in Slovakia, while response diversity "deserts" were identified in Czechia and Germany and for durum wheat in southern Europe. Positive responses to abundant precipitation were lacking. This assessment suggests that current breeding programs and cultivar selection practices do not sufficiently prepare for climatic uncertainty and variability. Consequently, the demand for climate resilience of staple food crops such as wheat must be better articulated. Assessments and communication of response diversity enable collective learning across supply chains. Increased awareness could foster governance of resilience through research and breeding programs, incentives, and regulation.

Keywords: Europe; climate resilience; cultivar; response diversity; wheat.

Fig. 1.

Decline in climate resilience of wheat on farmers’ fields after 2002–2009 in most European countries. The long-term trends of the diversity of the responses to critical weather patterns (response diversity), illustrating the climate resilience and the diversity of cultivars (type diversity). True diversities are shown representing the exponential of the Shannon index [exp(H)] (36, 37). All of the cultivar yield data were utilized (n = 100,985).

Fig. 2.

Increase in the climate resilience of European wheat with increasing response diversity. The main figure shows the decrease in the variation in the percentage yield response to the weather patterns (agroclimatic PCs) critical to yield due to the increase in the number of weather response clusters considered. All of the cultivar yield data were utilized (n = 100,985). The box shows how combining cultivars from different clusters increases the yield stability under weather variability. The three exemplary cultivars (dark, yellow and green heads) represent clusters 1, 3 and 5, respectively, from Caslav, Czechia and were selected based on the largest number of observations and similar average yields (n = 78). If the cultivation area was evenly divided among the three cultivars from 2001 to 2007 in comparison with the cultivation of only the cultivar with the highest total yield (Apache), a 2% loss in total yield appeared, but the SD among the years declined by 16–32%. The relative size of the heads refers to the relative annual yields of the three cultivars.

Fig. 3.

Climate resilience hotspots and deserts of European wheat. The country charts show the percentages of cultivars in each weather response cluster with different responses to weather patterns (agroclimatic PCs) critical to yield in cultivar trials. The colored (green to orange) areas on the map illustrate the response diversity classes based on the proportion of the dominant cluster (>90 to <50%), the number of other simultaneously important clusters (0–4), and the trends. All of the cultivar yield data were utilized (n = 100,985).