Abrupt vegetation changes in the Segura mountains of southern Spain throughout the Holocene

Abstract

1. The fossil pollen record of Cañada de la Cruz in the Segura mountains of southern Spain yields insights into high-elevation vegetational dynamics over the last c. 8320 years. Phases of xerophytic grassland alternate with high-mountain open pine forests and expansion of deciduous forests and Mediterranean scrub at lower altitudes. 2. Longer-term stable vegetation patterns are interrupted by multidecadal to century-scale shifts at about 7770, 3370, 2630, 1525 and 790 years BP. 3. Some of the vegetation types have no modern analogues and represent high-altitude remnants of widespread last-glacial xerophytic communities. Other species patterns, characteristic of current scrub associations, appeared only within the last 800 years. 4. The sequence fits within the regional context of a generally wet mid-Holocene (c. 7700-3300 years BP) characterized by spread of mesophilous vegetation, between drier conditions characterized by greater abundance of xerophytes. 5. The pollen record and current ecological studies on high-elevation vegetation of Mediterranean Spain suggest that control of vegetation is primarily climatic although grazing pressure, which would have pushed vegetation over a threshold for change, cannot be discounted.