Climate change impacts on thermal growing conditions of main FRUIT species in Portugal - El cambio climático impacta en las condiciones térmicas de crecimiento de las principales especies de FRUTALES en Portugal

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Thermal growing conditions of temperate fruit and nut species in Portugal are assessed by two indices: growing degree hours (GDH) and chilling portions (CP). The first evaluates growing season heat accumulation (February–October), while the second determines chill accumulation during dormancy (October–February). These two indices are estimated based on gridded daily minimum and maximum temperatures from a gridded observation-based dataset (E-OBS). Both indices are statistically downscaled to a 1 km grid over mainland Portugal for 1981–2015 (35 years). Furthermore, multi-model climate change projections are provided using four EURO-CORDEX global-regional climate model chains under two future emission scenarios (RCP4.5 and RCP8.5, 2041–2070). 

Overall, increases of heat accumulation and decreases of chilling accumulation are projected over most of Portugal. However, owing to frequent above-optimum temperatures for temperate fruit trees, decreases of heat accumulation are expected over inner southern Portugal, which combined with significant reductions of winter chill make this region the most affected by climate change. Crop-specific GDH/CP diagrams for eight fruit classes (carob tree, almond tree, chestnut tree, citrus fruits, fresh fruits trees, olive trees, pine nut trees and vines) are analysed taking into account their current spatial distributions.

Shifts in their thermal conditions under future scenarios are discussed. Thermal growing conditions of fruit species are innovatively assessed using suitable heat and chilling accumulation measures at very-high spatial resolution and under current and future climates in Portugal. These results may support the Portuguese fruit production sector in planning future strategies to cope with climate change.

Source: Santos, J.A., Costa, R. & Fraga, H. Climatic Change (2016). doi:10.1007/s10584-016-1835-6 (http://link.springer.com)