Páscoa P, Gouveia C M, Russo A, Trigo R M
Instituto Dom Luís, Faculdade de Ciências da Universidade de Lisboa, Campo Grande. Edifício C8, Piso 3, 1749-016, Lisbon, Portugal.
Int J Biometeorol. 2017 Mar;61(3):439-451. doi: 10.1007/s00484-016-1224-x. Epub 2016 Oct 28.
The production of wheat in the Iberian Peninsula is strongly affected by climate conditions being particularly vulnerable to interannual changes in precipitation and long-term trends of both rainfall and evapotranspiration. Recent trends in precipitation and temperature point to an increase in dryness in this territory, thus highlighting the need to understand the dependence of wheat yield on climate conditions. The present work aims at studying the relation between wheat yields and drought events in the Iberian Peninsula, using a multiscalar drought index, the standardized precipitation evapotranspiration index (SPEI), at various timescales. The effects of the occurrence of dry episodes on wheat yields were analyzed, on regional spatial scale for two subperiods (1929-1985 and 1986-2012). The results show that in western areas, wheat yield is positively affected by dryer conditions, whereas the opposite happens in eastern areas. The winter months have a bigger influence in the west while the east is more dependent on the spring and summer months. Moreover, in the period of 1986-2012, the simultaneous occurrence of low-yield anomalies and dry events reaches values close to 100 % over many provinces. Results suggest that May and June have a strong control on wheat yield, namely, for longer timescales (9 to 12 months). A shift in the dependence of wheat yields on climatic droughts is evidenced by the increase in the area with positive correlation and the decrease in area with negative correlation between wheat yields and SPEI, probably due to the increase of dry events.
伊比利亚半岛的小麦产量受到气候条件的强烈影响，尤其易受降水年际变化以及降雨和蒸发散长期趋势的影响。降水和温度的近期趋势表明该地区干旱加剧，因此凸显了了解小麦产量对气候条件依赖性的必要性。本研究旨在利用多尺度干旱指数——标准化降水蒸发散指数（SPEI），在不同时间尺度上研究伊比利亚半岛小麦产量与干旱事件之间的关系。分析了干旱事件发生对小麦产量的影响，研究区域空间尺度上两个子时期（1929 - 1985年和1986 - 2012年）的情况。结果表明，在西部地区，较干燥的条件对小麦产量有积极影响，而在东部地区情况则相反。冬季月份对西部影响较大，而东部则更依赖春季和夏季月份。此外，在1986 - 2012年期间，许多省份低产异常与干旱事件同时发生的比例接近100%。结果表明，5月和6月对小麦产量有很强的控制作用，即在较长时间尺度（9至12个月）上。小麦产量与SPEI之间正相关区域增加、负相关区域减少，这可能是由于干旱事件增加，证明了小麦产量对气候干旱依赖性的转变。
