# Exploring Ecosystem Functioning in Spain with Gross and Net Primary Production Time Series
## 3 Study Area  
Peninsular Spain is located in the southwest of Europe, approximately between (44\({}^{\circ}\), \(-10^{\circ}\)) and (36\({}^{\circ}\), 3\({}^{\circ}\)) lat/lon. The ecosystem's diversity, mainly caused by its orography (itselevation ranges from sea level to 3479 m), is remarkable. Its geographical location leads to a range of climates from Atlantic in the northwest to semiarid in the southeast. Its annual precipitation follows the same gradient, ranging from around 2000 mm in the northwest to around 200 mm in the southeast. Figure 1a,b show the spatial distribution of the average annual precipitation and the average annual \(T\) for the 2004-2018 period. According to the land cover map by [25] (Figure 1c), 52% of the pixels of the study area are classified as croplands, 21% as forests, and 25% as shrublands, grasslands, or sparse vegetation. Figure 1d shows the forest type map used in the simulation of forest respirations [28]. Forests in Peninsula Spain present great spatial complexity and GSV irregularity. According to the Third Spanish Forest Inventory, 56% of the forest areas covered by tree species are broadleaved forests with _Quercus iz_ as the most common species, while the other 34% are needle-leaved forests with majority of _Pinus halepensis_[44]. Ten sites representative of the study area (Table 1) were selected to examine their seasonal variations. One site was chosen for each vegetation type indicated in Figure 1c,d. Figure 1: Spatial distribution of the average annual precipitation (**a**) and the average annual \(T\) (**b**) for the 2004–2018 period. Black crosses refer to the location of the sites used for the local analysis (A–J). (**c**) Vegetation type map [25] used in the estimation of the GPP: GRA (grasslands), SHR (shrublands), CRO (rainfeed croplands), ICRO (irrigated crops), MCRO (mosaic cropland), BF (broadleaved forest), NF (needle-leaved forest), MF (mixed forest), SPV (sparse vegetation). (**d**) Specific forest type map used to derive the NPP: EBF (evergreen broadleaved forest), LDBF (low-altitude deciduous broadleaved forest), HDBF (high-altitude deciduous broadleaved forest), LENF (low-altitude evergreen needle-leaved forest), and HENF (high-altitude evergreen needle-leaved forest). These data are described in Section 2. All sites present ecoclimatic features representative of the corresponding vegetation type except site F, which presents higher air temperature. Site A is a sparse vegetation region located in the southeast of Spain, at the north of _Desierto de Tabernas_, in the province of _Almeria_, characterized by pronounced dry conditions causing desertification. Site B is a grassland located at the east of the province of _Badajoz_, in the interior of Spain. Site C is a shrubland located at the southwest of the province of _Valencia_, in the east of Spain. Site D is a rainfed cropland located in the province of _Cuenca_. Site E is an irrigated cropland located in the province of _Lleida_, in the _Ebro_ basin. Forest sites (F-J) are located in or near to national parks. Site F is an evergreen broadleaved forest, particularly, the most extensive cork forest in Spain and one of the largest in the world dominated by _Quercus super_. Site G is a deciduous broadleaved forest located in the second largest and best preserved beech forest in Europe, the national park _Selva de Iranti_, in the province of _Navarra_ (north of Spain). Site H is a high-altitude deciduous broadleaved forest located at the southeast of _Picos de Europa_. Site I is a low-altitude evergreen needle-leaved forest located in the national park of _Sierras de Cazorla_, _Segura y las Villas_, the Spanish largest continuous area of pine forest with representatives of nearly all pine species found in the Iberian Peninsula, the most abundant being _Pinus nigra_. Site J is a high-altitude evergreen needle-leaved forest located in the north of the national park _Serrania de Cuenca_, in the province of _Guadalajara_.