Blanca Ruiz-Zapata

Upper Pleistocene and Holocene palaeoenvironmental records in Cueva Mayor karst (Atapuerca, Spain) from different proxies: Speleothem crystal fabrics, palynology, and archaeology

The Cueva Mayor karst system of Atapuerca, in Northern Spain, hosts a highly significant record of human occupation from the Pleistocene. The climatic context of the human activities during the Pleistocene-Holocene for this inland site has not been well constrained, since existing records of the palaeoclimatic evolution of the Northern Iberian Peninsula are from more distal coastal and high-elevation sites. In this study, we interpret the palaeoenvironmental information recorded on the petrography of a stalagmite and the pollen spectra of the Sierra de Atapuerca karst system during the last 20 kyr. The integration of both types of records has allowed us to define four palaeoenvironmental stages. During the Upper Pleistocene and until 12.8 kyr BP, the climate was cold and dry, toward the end of the interval evolving to wetter and warmer conditions. From 12.8 to 7.7 kyr BP, during the Mesolithic-Neolithic, a major erosion event in both records marks the Pleistocene-Holocene transition. Around 5.9 kyr BP, the Late Neolithic, environmental conditions indicate a climatic optimum with a marked seasonality. The environmental conditions became drier from 4.2 kyr BP until the present, with a decrease in the woodlands. This aridity signal might be amplified by the impact of a more intense human agricultural activity after 3.1 kyr BP, during the Bronze Age.

Predicting the natural vegetation in a region by comparing the pollen in two biological vectors: bryophytes and honey

Abstract The range of pollen that can be found around the city of Sigüenza has been analysed (La Alcarria, north-eastern region, Guadalajara, Spain), an area currently included in the territory comprising the Protected Origin Denomination ‘Miel de la Alcarria’. We studied the pollen recovered from two different types of biological sensors: bryophytes, live material used to study the recent pollen rain, and honey. The aim of this study was to try to establish the relationship between the pollen collected from both types of sensors and the existing natural vegetation in the area using comparative statistical methods. More than 7500 pollen grains were observed from the bryophyte samples and included 35 pollen types. Conversely, the pollen present in 37 honey samples contained 46 pollen types with a total of 46 000 pollen grains counted. The data presented in this study proves the relationship between the bryophyte pollen spectrum and the local vegetation present in a geographical area. However, it indicates that the pollen content in honey is a more effective measurement to determine spatial distribution of the plant species. We conclude that the pollen present in honey may better predict the vegetation in a region than that recovered from bryophytes.