North-South divide: contrasting impacts of climate change on crop yields in Scotland and England

Abstract

Effects of climate change on productivity of agricultural crops in relation to diseases that attack them are difficult to predict because they are complex and nonlinear. To investigate these crop-disease-climate interactions, UKCIP02 scenarios predicting UK temperature and rainfall under high- and low-CO(2) emission scenarios for the 2020s and 2050s were combined with a crop-simulation model predicting yield of fungicide-treated winter oilseed rape and with a weather-based regression model predicting severity of phoma stem canker epidemics. The combination of climate scenarios and crop model predicted that climate change will increase yield of fungicide-treated oilseed rape crops in Scotland by up to 0.5 t ha(-1) (15%). In contrast, in southern England the combination of climate scenarios, crop, disease and yield loss models predicted that climate change will increase yield losses from phoma stem canker epidemics to up to 50 per cent (1.5 t ha(-1)) and greatly decrease yield of untreated winter oilseed rape. The size of losses is predicted to be greater for winter oilseed rape cultivars that are susceptible than for those that are resistant to the phoma stem canker pathogen Leptosphaeria maculans. Such predictions illustrate the unexpected, contrasting impacts of aspects of climate change on crop-disease interactions in agricultural systems in different regions.

Figure 1.

Relationships between different components of the modelling and analysis. (1) Weather data were generated for five UKCIP02 climate change scenarios (baseline (1960–1990), 2020LO, 2020HI, 2050LO, 2050HI) for 15 sites over the UK (Semenov 2007). (2) These weather data were inputted into an oilseed rape crop growth simulation model, STICS (Brisson et al. 2003) and a weather-based regression model for predicting severity of phoma stem canker epidemics, PASSWORD (Evans et al. 2008). (3) The STICS model was used to generate yield data for crops treated with fungicides against diseases for each site/climate change scenario (figure 2). A yield loss model was used to estimate yield losses from stem canker severity predictions for oilseed rape cultivars that were susceptible (figure 3) or resistant (figure 4) to Leptosphaeria maculans. (4) Fungicide-treated crop yield data and yield loss data were interpolated according to UK government regions as used in the 2006 Defra Agricultural and Horticultural Survey and combined to estimate untreated crop yields (table 1).

Figure 2.

Predicted yield of oilseed rape (treated against diseases). Predicted yields (t ha⁻¹) of fungicide-treated winter oilseed rape for (a) baseline, (b) 2020LO, (c) 2020HI, (d) 2050LO and (e) 2050HI climates. The maps are interpolated from yield data generated for 15 UK sites using the STICS crop growth model. Winter oilseed rape crops are generally grown in the eastern halves of England and Scotland; less fertile and mountainous areas in the west are unsuitable for arable crops.

Figure 3.

Predicted yield loss from phoma stem canker for cultivars susceptible to L. maculans. Predicted yield loss (% of maximum yield from fungicide-treated plots) from phoma stem canker for susceptible cultivars (HGCA resistance rating 1–5), for (a) baseline, (b) 2020LO, (c) 2020HI, (d) 2050LO and (e) 2050HI climates. The maps are interpolated from yield loss data generated for 15 UK sites using a weather-based canker severity model, a yield loss model and the crop model.

Figure 4.

Predicted yield loss from phoma stem canker for cultivars resistant to L. maculans. Predicted yield loss (% of maximum yield from fungicide-treated plots) from phoma stem canker for resistant cultivars (HGCA resistance rating 6–9), for (a) baseline, (b) 2020LO, (c) 2020HI, (d) 2050LO and (e) 2050HI climates. The maps are interpolated from yield loss data generated for 15 UK sites using a weather-based canker severity model, a yield loss model and the crop model.