Valles del Jubera, Leza, Cidacos y Alhama: Exploring the Protected Geography of La Rioja

The reserve was formally designated as a UNESCO biosphere reserve on 9 July 2003, following recognition that the valleys of the Jubera, Leza, Cidacos, and Alhama combined exceptional natural and cultural values. The designation brought together an area that had already attracted scientific and public attention for its dinosaur track sites, its thermal springs at Arnedillo, and its rural heritage tied to the traditional villages of the Camero region.

The divisions of the reserve, a 5,537-hectare core zone, a 11,760-hectare buffer zone, and a 102,372-hectare transition zone, were structured to keep the strictest protection in the most ecologically sensitive areas while allowing continued economic activity in the parts of the territory that include inhabited villages. Additional protection layers overlap with parts of the reserve, including several Special Protection Areas for birds that have been recognized under European Union nature directives.

Beyond the modern designation, the valley has a long human history. Celtiberian communities occupied hilltop sites such as those at Inestrillas and Contrebia Leukade, leaving behind place names, settlements, and other archaeological evidence that remain embedded in the cultural landscape of the protected area.

The landscape of the biosphere reserve is shaped first by its four river valleys. The Jubera, Leza, Cidacos, and Alhama rivers run roughly parallel through the southern portion of La Rioja, incising deep ravines into the limestone bedrock and producing cliffs, galleries, and narrow gorges that define much of the reserve's scenery.

Above these valleys rises a mid-mountain relief that ranges from around 450 meters in the lower valleys up to approximately 1,758 meters at the highest points. Slopes alternate between open pasture, cereal fields, and forested hillsides. Dryland agriculture has refined much of the land into terraces, vega floodplain gardens, and other cultivated forms. The combination of river-cut rock, agricultural steps, and forested ridges creates a varied terrain typical of the Iberian System foothills.

The vegetation of the reserve reflects a Mediterranean mountain mosaic shaped by altitude, aspect, and traditional land use. On the sunnier slopes, holm oak, oak, and Scots pine form the backbone of the forested landscape, accompanied by patches of more demanding species such as beech and Portuguese oak in the higher, cooler zones.

Beneath the tree canopy lie extensive areas of low shrubland dominated by juniper and rockrose, along with open pastures used for livestock grazing. The dryland fields scattered across the reserve, including cereals, vineyards, and small kitchen gardens along the vega, add an agricultural layer to the ecological mosaic. Across this variety of habitats, the reserve sustains a rich and diverse fauna, with particular importance for steppe and cliff-nesting bird species.

Because the reserve overlaps with several designated bird protection areas, including Peñas del Iregua, Jubera y Leza, Peñas de Arnedillo, Peña Isasa y Peñalmonte, and Sierra de Alcarama y Valle del Alhama, its cliffs and open landscapes are notable for birdlife. These cliffs support raptors and other cliff-nesting species, while the steppe-like agricultural areas and shrublands host bird communities typical of Mediterranean mountain interiors.

Larger mammals typical of the Iberian mid-mountains are present in the reserve's forests and rocky terrain, and the rivers themselves maintain associated riparian fauna. The dinosaur tracks preserved in the Cidacos valley, while not a living wildlife feature, are an essential component of the reserve's natural heritage and are managed as a paleontological resource.

The reserve is managed as a biosphere reserve under UNESCO's Man and the Biosphere programme, with a tiered zoning system designed to reconcile ecological protection with the presence of inhabited villages and economic activity. The 5,537-hectare core zone concentrates the strictest protection, the 11,760-hectare buffer zone provides a transition, and the 102,372-hectare transition zone accommodates most of the human presence, agricultural land, and rural settlements.

Overlapping protection layers strengthen the reserve's conservation profile. Parts of the territory are included in Special Protection Areas for birds, which are recognized under European Union nature directives and add an additional layer of legal protection. The reserve thus combines landscape-scale biodiversity conservation with the safeguarding of cultural heritage, paleontological sites, and traditional land-use systems.

The valleys encompassed by the reserve carry a deep and continuous human history. Celtiberian communities established settlements on strategic heights such as the ancient site of Contrebia Leukade near Aguilar del Río Alhama, and other archaeological remains are scattered across the four valleys. This pre-Roman heritage remains an essential element of the region's identity.

In more recent centuries, the land has been shaped by mountain villages of the Camero region and the agricultural and pastoral practices of La Rioja's southern valleys. Terraced agriculture, transhumant grazing, and dryland cereal cultivation have all left visible marks on the landscape. Today the reserve supports a living rural culture of roughly 10,000 inhabitants across 27 fully included municipalities and 13 partially included ones.

Among the reserve's most distinctive features are the four parallel river valleys that give it its name, each cutting dramatic limestone gorges through the Iberian System foothills. The area's paleontological value is exceptional: the Cidacos valley preserves one of Europe's most important concentrations of dinosaur trace fossils, with sites such as those around Enciso regularly drawing visitors. The thermal springs of Arnedillo add a hydrological highlight, while hilltop Celtiberian villages and the quiet rural landscapes of the Camero area provide a strong cultural counterpoint.

Spring and autumn are generally the most rewarding seasons to experience the reserve. Spring brings fresh greenery in the forests and flowering shrublands, while autumn colors the broadleaf woodlands and coincides with harvest activity in the dry-farming villages. Summer remains appealing for the cooler temperatures of the mid-mountain landscape, though higher areas receive intense sun, and winter can bring snow to the highest elevations above 1,500 meters, leaving the valleys quieter and more atmospheric.