The study sites were selected based in the following criteria: (i) garantie of a climatic gradient; (ii) existence of a groundwater gradient; (iii) coastal dune forest (in sandy soils); (iv) data availability and infrastructures.
Plot created by Universidad de Sevilla, in Reserva Biológica de Doñana, Spain (Serrano & Zunzunegui, 2008). In the study area, it can be found temporary ponds (prioritary habitat of the european habitat directive), floodable in certain periods of the year (autumn and winter), in sandy soils and favored by a clay horizon (semi-permeable) very dependent on annual rainfall and recharge capacity. The study site is composed by the temporary ponds, mediterranean thickets, juniper forest and pinewood. The vegetation is dominated by hydrophytic and xeric shrubs (such as Erica scoparia, Corema album, Halimium sp.) and mediterranean trees (Juniperus phoenicea, Quercus suber and Pinus pinea).
The presence of a tourist complex and irrigated crops near the study site imply a strong impact upon the vegetation and hydric conditions of the study area (Serrano and Zunzunegui 2008), and this water exploitation creates a groundwater gradient throughout our study site.
The climate is typically mediterranean, with the rainy period between october and march, and dry hot summers. Annual precipitation is lower compared to the other study sites: in a rainy year it can be found annual values higher than 712mm but in a dry year annual precipitation can be lower than 355mm. Temperature in the dry season can easily reach 40ºC, and lower temperatures are reached in the winter time, existing a high thermal amplitude over the year.
Plot created by CBA-FCUL, in Osso da Baleia, Portugal (Maguas et al, 2011). It is a pine forest, situated north of Leiria, constituted by north-south dune belts where many dune slacks exist. Maximum elevation is 77m and is oriented from west to east. Vegetation is characterized by a primary dune belt with a herbaceous and shrub formation, and a pine forest (Pinus pinaster) in the stabilized secondary dune. In the pine forest it can be found other tree species (such as Myrica faya), shrub species (such as Corema album) and dune slacks considered in the Natura 2000 network as the habitat 2170 - Dunes with Salix repens ssp. argentea (ICNB 2006). The soil is mainly constitute by sand.
In this area the national electric and gas storage company (REN, S.A) is exploiting, since 2001, the groundwater for gas storage purposes. To assess subterranean caverns, the groundwater has to be extracted and, for that, the company uses 20 extraction wells (distributed in our study area). The groundwater extraction is limited to 600m3/h with a maximum of groundwater lowering of 5m. Additionally, 14 piezometers exists throughout the area with daily groundwater level measurements.
The climate is meso-mediterranean, with frequent rainy events in winter and spring (November to April, with a monthly average of about 150mm) and a period of less precipitation in the summer (July to August), being the annual total amount of precipitation c. 900mm. The highest temperatures (approximately 37ºC) are in the dry season, and the lowest temperatures in the rainy season.
Plot created and monitored by BIOTA/FAPESP project - Restinga, in Ubatuba -SP, Brazil (Joly et al, 2008; Vieira et al., 2008). Restinga is a vegetation formation integrated in the Parque Estadual da Serra do Mar – PESM, in the Picinguaba Nucleo. The vegetation represents the Restinga fisionomy (according to the brazilian national classification system: IBGE (Veloso et al., 1991), being considered a pristine forest in coastal areas with an elevation between 0 and 10m. Restinga soil is classified as Neosolo Quartzarenic and has a high sand content, low pH, low phosphorus concentration and a high aluminium saturation.
The climate in Ubatuba region is, according to Kopper (1948) classified as Af (Tropical rainforest climate), with a mean annual precipitation of approximately 3000 mm (and with less precipitation in june: about 87 mm) and mean annual temperature of 22ºC.