Climate Warming Effects on the Olea Europaea–Bactrocera Oleae System in Mediterranean Islands: Sardinia as an Example

Global Change Biology, April 2009, 15:2874–2884

Luigi Ponti , Q. Antonio Cossu, and Andrew Paul Gutierrez

“Global warming will affect all species but in largely unknown ways, with certain regions such as the Mediterranean Basin and its major islands including Sardinia being particularly vulnerable to desertification. Olive (Olea europaea) is of eco-social importance in the Mediterranean where it was domesticated. This drought-resistant crop and its major pest, the olive fly (Bactrocera oleae), have tight biological links that make them a suitable model system for climate change studies in the Mediterranean. Here a physiologically based weather-driven demographic model of olive and olive fly is used to analyze in detail this plant–pest system in Sardinia under observed weather (10 years of daily data from 48 locations), three climate warming scenarios (increases of 1, 2 and 3 °C in average daily temperature), and a 105-year climate model scenario for the Alghero location (e.g. 1951–2055). GRASS GIS is used to map model predictions of olive bloom dates and yield, total season-long olive fly pupae, and percent fruit attacked by the fly. Island wide simulation data are summarized using multivariate regression. Model calibration with field bloom date data were performed to increase simulation accuracy of olive flowering predictions under climate change. As climate warms, the range of olive is predicted to expand to higher altitudes and consolidate elsewhere, especially in coastal areas. The range of olive fly will extend into previously unfavorable cold areas, but will contract in warm inland lowlands where temperatures approach its upper thermal limits. Consequently, many areas of current high risk are predicted to have decreased risk of fly damage with climate warming. Simulation using a 105-year climate model scenario for Alghero, Sardinia predicts changes in the olive–olive fly system expected to occur if climate continued to warm at the low rate observed during in the past half century.”

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