The experimental sites were chosen primarily based on their very distinct climates but also as a function of accessibility and logistical support.
The climate in Murcia is Mediterranean with semi-arid features, with an average annual temperature between 15.0 ºC and 19.0 ºC and short winters and long and hot summers. The annual rainfall is less than 350 mm, except for some areas in the upper northwestern lands where it exceeds 600 mm, rainfall distribution is irregular with long dry periods combined with short and intense rainfall events (Alonso-Sarría et al., 2016).
Toledo has a continental semiarid climate with an annual rainfall of 487 mm and an average annual temperature of 14.0 oC (Hernández et al., 2007).
The climate in Évora is typically Mediterranean, with a hot and dry summer. More than 80% of annual precipitation occurs between October and April. The long-term mean annual temperature is 15.0-16.0 oC and an average annual precipitation of 669 mm (Pereira et al., 2007).
The most significant feature of the Porto climate is the annual rainfall level (1236 mm) and its irregular distribution throughout the year, mainly concentrated in winter and spring. Due to the maritime influence Porto has mild temperatures with an annual mean of 14.4 oC. No cold season can be found in Porto, being January the coldest month, with an average of 9.3 oC. The mean summer temperature is about 18.1 oC, although between May and September, very high temperatures can be reached (Abreu et al., 2003).
In Jaca, climate conditions are typically alpine, with cold mean annual temperatures that ranged between -0.7 oC and 5.0 oC and high-mean annual precipitation values well distributed along the year (Garcia-Pausas et al., 2007).
In Peñalara, the mean annual temperature is 6.3 oC, with the coldest months being between December and April and hottest months being July and August. Annual precipitation is 1357 mm, the wettest months are between October and May and the driest being between July and August, with higher precipitation being in late autumn and early winter (Palacios et al., 2003).